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IPTC 2013: International Petroleum Technology Conference
- Conference date: 26 Mar 2013 - 28 Mar 2013
- Location: Beijing, China
- Published: 26 March 2013
101 - 150 of 581 results
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Wellbore Stability Evaluation Guideline For Reducing Non-Productive Time
More LessWellbore instability is one of the most critical challenges affecting drilling and production. Borehole instability in both shale and sand formations, hole collapse, lost circulation, stuck pipe, sanding, and other related well failures can be avoided by meticulous and careful design of drilling plan, specially by determining the critical mud weights and mud fluid components which will provide sufficient support for the wellbore during drilling operation. This paper presents a systematic program and guideline of comprehensive geomechanics investigation and evaluation that includes drilling and log data analysis for rock strength and earth stress model construction, stress regime influence, laboratory triaxial stress-strain tests on well core samples considering bedding plane inclination effects, failure criterion consideration, and optimum mud-weight (MW) window for secure and stable well drilling. The continuous well production can also cause problems for in-field drilling as the severe pressure depletion and reservoir compaction would inevitably induce significant reduction in stresses and formation fracture gradient both inside the reservoir and significantly upward into the caprock formations depending on the reservoir/formation stiffness contrast, reservoir size, thickness and depth, etc. This paper addresses those issues with the optimum MW reexamined and recalculated based on the largely altered in-situ stresses and wellbore strengthening application if necessary. This paper will describe theories, some issues in wellbore stability work, discuss some uncertainties from authors’ experience, lessons learned and guidelines for wellbore stability evaluation.
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Application of Low Pressure System at Balingian, Sarawak Brown Field; Candidate Selection and BY Field Case Study
Authors M. Syahezat Ismail and N. HamzaBayan (BY) is a brown field located in Sarawak region with over 25 years of production. Declining trend in field production resulting from rapidly declining reservoir pressure and increasing water production has prompted aggressive production enhancement activities to arrest further decline. Conventional gas lift method has been widely applied across the field and has provided reliable means of artificial lift to sustain production. However, wells with very low reservoir pressure were not able to sustain production even with gas lift due to the back pressure experienced in the production system. Low Pressure System (LPS) were implemented in two (2) out of four (4) drilling platforms in BY to sustain and increase the field production, reactivate idle wells and to manage the back pressure for the whole production system. Experience gathered from this implementation enable us to improve the candidate selection process and to share potential limitation imposed by the LPS system to operation. Actual BY LPS performance is shown here to illustrate the proven success in increasing the field production and unlocking some of BY reserves. The change in the production trend of well’s producing in current production system and after being tied to LPS will show the total achieved production gain which in BY case amounted to more than 1.5 million barrels in 4 years of operation.
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A Successful Subsalt Exploration Example of M Block in The Eastern Margin of Precaspian Basin
Authors Zhen Wang, Junzhang Zheng, Yankun Wang and Man LuoM block in eastern margin of Precaspian Basin is the first CNPC ’s risk exploration project in Central Asia & Russia, which has been prospected by many companies and no discovery was found. The main exploration difficulties are subsalt trap recognition’s trouble caused by salt domes with giant thickness (greater than 1000m) which lead to subsalt target stratum’s pull-up and false faults in the Permian and strong heterogeneous reservoir prediction in carbonate reservoir buried near 4000m. Technology was developed based on the difficulties, in the aspect of subsalt structural recognition, fine interpretation by multidisplay methods, salt domes’ margin identification using boundary detecting technique, time-depth conversion methods of raytracing procedure, forward modeling examining velocity field’s precision, vertical seismic profiling (VSP) detecting local structural shape, palaeotectonic restoration analyzing trap’s origin, prestack depth migration verifying trap’s validation, salt dome’s influence was wiped out continuously and strata’s real shape was resumed which leads to the increase of drilling success ratio. In the aspect of carbonate reservoir prediction, favorable reservoir zones in Carboniferous strata were outlined based on the study of logging assessment, sequence stratigraphy, sedimentary facies, seismic inversion, fracture and petroleum detection, attribute analysis. At the same time, REI(reservoir evaluation index) and CI(cave index) indexes were initiated, and carbonate reservoir’s logging assessment standard in this block was established that improves reservoir prediction’s precision. In the aspect of comprehensive evaluation, 3 structural accumulating belts were divided after the study of reservoir types, which are west structural belt, central structural belt and east structural belt. The different belts’ play was evaluated synthetically. The main and potential play was pointed out in different belts. The regular patterns about subsalt carbonate accumulating were generalized. Middle ramp region should be break through first is our bulk exploration deployment clue, and a big field with more than a hundred million tons reserves was discovered which is the biggest subaerial discovery since the Kazakhstan being self-governed and guarantees the abundant supply for the Central Asian pipeline.
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Sichuan Shale Gas Microseismic Monitoring: Acquisition, Processing, and Integrated Analyses
The ability to estimate the stimulated reservoir volume and to enhance the effectiveness of hydraulic fracturing operation is fundamental in field development planning and critical to optimizing well completion in unconventional gas exploration and production. Microseismic Monitoring (MSM) survey provides essential observations study how induced rock volume responds seismically under field hydraulic fracture stimulation. Recent advanced microseismic technology with further development can provide real-time monitoring and interpretation which will improve hydraulic fracturing efficiency and better EUR, stop induced fracture development toward fault zones, and avoid connecting water-bearing layers. Advanced processing can enhance weaker microseismic signal, which provides a more complete Microseismically-Stimulated Reservoir Volume (M-SRV). M-SRV is essential to build the 3D understanding of the induced fracture network under various stimulation designs in volumes and in patterns from each fracturing stage.
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Modelling the Transient Behaviors of the Kinetics in the Transesterification of Palm Oils Reveals Prospects for Customization of Esters for Drilling Fluids Formulation
By E.O. OkekeThis paper discusses the prospects for customizing esters derived from palm oils as part of the first phase of a study to develop new drilling fluids. This phase evaluates the feasibility and prospects for customizing such esters in order to fully define experiments and all analytical conditions for realizing the objectives of the entire study. Published studies in transesterification show products from various vegetable oils for different applications including biodiesel production. Vegetable Oils consist of triglycerides (TG) 90 - 98 % by weight, small diglycerides (DG) and monoglycerides (MG), while palm oil contains TG 95.7%, DG 3.7%, and MG 0.6%. Transesterification of vegetable oils with alcohol is characterized by multiple consecutive and reversible reactions. TG is converted stepwise to DG, MG and finally glycerol (GL). We are particularly interested in palm oils (developed in large plantations in Nigeria). ASPEN HYSYS 7.3 was used to model the non acid catalyzed transesterification involving three reactions each with methanol for conversion of TG, DG and MG under steady state and transient conditions in a CSTR at varied reaction conditions and time to produce varied esters properties. Results from the model show prospects for customizing esters derived from the transesterification of palm oils and realizing their application in drilling fluids formulation.
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Knowledge Management in Engineering Activities of an Operating Company
Authors G. DiLiddo, G. Gabetta, F. Ponti, P. Cavassi and P. FassinaA better Management of Knowledge is an actual need in the Oil&Gas industry. In the past years, as a matter of fact, the amount of information available to engineers and scientists increased exponentially thanks to developments of the ICT tools making therefore harder to handle it. On the other hand, industry practice is to keep the plant running, implying that decisions have to be made quickly and time is short to collect and examine all the possible information. A solution to these challenges is Knowledge Management, which is defined as the ensemble of processes that allow to capture, validate, consolidate, archive, re-use and diffuse knowledge in order to improve both business processes and innovation processes. To make it happen, new ICT tools and mindsets need to be developed and exploited. In Eni E&P Division, a Knowledge Management System (KMS) is operating since 2004 with the aim at facilitating and speeding-up the sharing of best practices, lessons learned and other Know How across the organisation; several ICT tools are employed, such as forums, mailing lists, SharePoint websites, webinars etc. The KMS is based on several Communities of Practice, which have the aim of conveying technical debate transversally to different disciplines and to the entire eni group, which is heterogeneous due to geographical location, culture, industrial sectors and discipline involved. The resulting interactions, moreover, bring the advantage of making explicit (and durable) all the personal knowledge of the members that would otherwise got lost due to turnover and distance among the employees. Taking into account the results of the first few years of implementation of the KM system in the engineering area, this paper will summarize the successes and lessons learned during the operating life of the Communities, to trace a road map for the future work.
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Seismic Guided Drilling: Near Real Time 3D Updating of Subsurface Images and Pore Pressure Model
More LessSeismic guided drilling (SGD) is a workflow that uses drilling information from a well being drilled and existing surface seismic data plus offset well information, to recalibrate and update the existing 3D earth model, including seismic image, pore pressure, fracture gradient, and geological hazards in order to reduce drilling uncertainty and mitigate drilling risk ahead of bit. The modern practices in drilling heavily rely on the predrill earth models. The predrill models often are not precise due to the inherent non-uniqueness in our remote sensing techniques. While LWD/SWD and WL provide useful information along the borehole, they offer little understanding about the rock property ahead of bit. SGD is such a technology that constantly improves the 3D earth model ahead of the bit through the integration of current well measurements with existing surface seismic data, with a turnaround time on the order of 24 hours. It not only corrects the model error behind the bit but also improve predictions ahead of the bit. The lack of adequate technologies, measurements, and turnaround time limitations, has made this type of optimum utilization/integration of seismic data and well data impractical until now. Recent developments in model building, rapid and accurate imaging technologies, and the availability of new well measurements, aided with modern engineering and computation, have made this optimum combination a reality. SGD has been used in several high-profile deep water HPHT wells worldwide with considerable successes. The technology is especially valuable in areas of low exploration activity or high geological complexity. The paper focuses on illustrating the concept of SGD technology and presenting a field example in the Gulf of Mexico, USA.
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Qualification Testing of Large Bore, HP Tubing Retrievable Safety Valves for Gas Wells
Authors M.A. Ali and A.S. AbdulrahmanOver the past decade, the role of natural gas has become increasingly important in fulfilling the ever-increasing energy needs of the world. Natural Gas has not only become an integral part of the world’s energy portfolio but also offers a cleaner and more efficient fuel to help reduce carbon emissions when compared to oil. Recently, Saudi Aramco has made three major offshore, high pressure, non-associated gas discoveries. A large bore completion design was selected for these fields in order to bring these discoveries on line quickly and cost effectively. The surface controlled, sub-surface safety valve is a critical component of the asset integrity management program for these gas wells. In order to meet the requirements of completion design and reservoir pressure, the world’s first 9-5/8in 10,000psi rated TRSSSV were developed tested and qualified for these developments. As part of qualification testing, high rate slam closure testing of the TRSSSV was carried out at the Southwest Research Institute and at GL Nobel Denton facilities. The objective of the tests was to ensure that TRSSSV closes, seals and continues functioning after a slam at the highest anticipated flow velocity in the wells. Additionally, slam test results were used to design surface and subsurface components that are required to operate the TRSSSV and must be capable of withstanding the shock load produced by a slam closure. Two leading completion companies were selected to develop and provide the TRSSSVs for these projects. Both designs suffered initial failures, required significant modification, and underwent extensive tests before the final designs were successfully tested. This paper discusses the basis of design, test criterion, results and lessons learned from the slam testing of the world’s first 9-5/8in, 10,000 psi rated TRSSSV. The paper also provides an overview of the two test facilities used, their limitations, and recommendations for future tests.
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An Experimental Study on Mitigation of Oil Well Cement Gas Permeability
Authors M.H. Ozyurtkan, G. Altun, I. Metin Mihcakan and U. SerpenPermeability development within and around the cement, placed in the casing-hole annulus in oil and gas wells, is a frequently encountered worldwide problem that might lead to various adverse economic and, possibly, catastrophic consequences. The resultant loss of hydrocarbon production and, sometimes, the wells constitutes the major part of the adverse economic impact. The loss of wells, in turn, might lead to severe environmental pollution and most importantly the loss of lives. Sustained casing pressure (SCP,) described as the pressure buildup due to flow through the permeable cement matrix or the micro annulus developed around the cement, had been experienced by about sixty percent of the wells producing oil and/or gas in the Gulf of Mexico, according to the literature. Although various methods are used to prevent the problem, there is no widely accepted universal method by the industry. Currently, the problem is attempted to be mitigated using distinct methods applied either during the cementing operations or after the problem is detected. The present study is an experimental investigation for the prevention of permeability development within and around the set cement at ambient conditions. A natural magnesium complex with carbonate, coded ARI, is used the first time ever as a cement additive to achieve desired prevention. Gas permeability measurements are conducted on the samples of cements of 19 different compositions, at the end of the successive curing periods up to 28 days. ARI containing cement samples are found to develope an impermeable matrix to gas flow and to exhibit no shrinkage in volume during setting. The performance of ARI as a cement additive is also investigated in the presence of other commonly used cement additives, e.g. friction reducer and fluid loss controlling agents.
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Well Failure Detection for Rod Pump Artificial Lift System through Pattern Recognition
More LessWell Failure Detection for Rod Pump Artificial Lift System through Pattern Recognition
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Fundamental Approaches to Dolomitization and Carbonate Diagenesis in Different Hydrogeological Systems and the Impact on Reservoir Quality Distribution
Authors Y. Xiao, F.F. Whitaker, A.B. Al-Helal, S. Stafford, E. Gomez-Rivas and S. GuidryThe accurate prediction of the geometry of subsurface dolomite geobodies, their connectivity, and the distribution of reservoir properties is a fundamental challenge in carbonate reservoir characterization. Reactive Transport Models (RTM) couple geochemical reactions with fluid flow to facilitate both 2D and 3D quantitative, process-based investigations of dolomitization and related carbonate diagenetic reactions. The paper will highlight new results and key conclusions from simulations of dolomitization mechanisms in four different hydro-geological systems: 1) Brine reflux, 2) Mixing zone and sub mixing zone, 3) Geothermal circulation and 4) Fault controlled hydrothermal circulation. Simulations provide new insights on the spatial distribution and dynamic behavior of: Geometry and distribution of dolomite bodies generated by different styles of subsurface fluid flow and their dynamic interactions; Regional versus local controls on dolomite occurrence and connectivity; Sensitivity and hierarchy of geological controlling parameters; Spatial and temporal relationships between dolomitization and associated diagenetic minerals including anhydrite cements and Mississippi Valley Type (MVT) mineralization; Effect of hydrothermal fluid induced dolomite recrystallization and anhydrite dissolution; Criteria to help identify the distribution of reservoir quality including high permeability dolomite “sweet spots”. When integrated with conventional subsurface data and stratigraphic, geochemical, and structural framework, Reactive Transport Models of dolomitization provide fundamental and robust predictive concepts and reservoir quality models for exploration and new / mature field developments. In particular, the state-of-the-art simulations allow the analysis and 3D visualization of dolomite body spatial and temporal evolution that can translate into alternative “process-based” well correlation methods and strategies for populating diagenetic bodies and their petrophysical properties in geological models for reservoir flow simulations.
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Rock Mechanical Properties of Shale Gas Reservoir and Their Influences on Hydraulic Fracture
More LessEach shale gas play is unique and the stimulation and completion method should be determined based on individual attributes. Selecting the completion style for an emerging shale play should begin in the laboratory rather than copy successful cases. An understanding of the rock mechanical properties is essential to help understand how the shale reservoir should be completed. We conducted triaxial compression tests for specimens from North America and South China. The failure modes and mechanical behaviors are analyzed. A new method combines rock mechanical properties and mineralogy to quantify the brittleness was derived and the practical use is demonstrated afterwards. Natural fracture analysis from core and borehole image are conducted and potentially active fractures, which could be most important hydraulic conduits and another index of the fracability, are identified through a three-dimensional Mohr representational method. The results of this study revealed that black shales are usually more brittle than imagined. Splitting and splitting-shear hybrid failure modes are the main failure modes under low confining pressures, while shear failure modes predominate under higher pressures. Types of shale, burial depth, coring direction and confining pressures are all affecting the mechanical behavior of specimens. The brittleness characterization of shale samples from China is similar to that from America. Compared with North America, shale from South China has higher strength and Young’s modulus, while lower Poisson’s ratio. A systematic approach of designing completion and stimulation is proposed based on brittleness, closure stress and hydraulic fracture width. The analyzing results from two shale gas wells verified the value of this method. Brittleness calculating results allied well with initial production of these wells, indicating good application prospects. Calculation of strength properties, closure stress and fracture width can be practical useful in selecting and designing stimulation measures.
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Fracture Optimization Applying a Novel Traceable Proppant and a Refined Mechanical Earth Model in the Congo Onshore
Authors R. Perfetto, P. Saldungaray, F. Martocchia, R. L. Ceccarelli, R. Lorefice, F. Rinaldi, L. Tealdi and P. DalmassoFracture stimulation has been adopted as an integral part of the completion in the M’Boundi field given the results achieved in enhancing well productivity, as well as the positive impact realized on field development economics. The fracturing process has been optimized over the years through improved reservoir understanding and ensuing implementation of technologies to address the uncovered challenges. Changes to the fracturing fluid formulation to prevent damaging the water sensitive reservoir rock, as well as modified proppant schedules to mitigate proppant embedment are examples of this improvement process. This paper describes the successful ongoing process of optimizing hydraulic fracturing designs in M’Boundi field. By applying an integrated approach combining various technologies, it was possible to better understand fracture propagation and coverage of the target reservoir. Implementation of a novel non-radioactive traceable proppant allowed accurate frac height measurement at the wellbore. When combined with rocks mechanics derived from sonic logs it led to redefining the mechanical earth model and ultimately the completion and fracturing strategy in the field. The process will be illustrated with examples from a 3-well campaign recently executed onshore Congo.
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Determining Coefficient of Quadratic Term in Forchheimer Equation
More LessForchheimer equation takes non-Darcy flow effect into account in the event of high flow velocity in porous media. Its application requires both permeability, which is in linear term, and Beta factor, which is in quadratic term. Permeability and Beta factor are determined by rock type, textural of rock, effective porosity, pore throat size, geometry of the pore, and connection and distribution of pores. Beta factor comes into play when the fluid flow rate is high and the flow rate deviates from Darcy’s law. Non-Darcy flow is described by Forchheimer equation. Usually the coefficient of non-Darcy flow term is hard to be determined. Existing approaches are core measurement and empirical correlations. To the best of our knowledge there is no theoretical equation available. To get an accurate estimation of flow rate or pressure drop in the reservoir, we need a method that has solid theoretical basis. The deficiency triggered our study. Starting from multiple-capillary tubes concept, we derived a rigorous relationship between pores geometry and pressure drop required for fluid flow through the pores. Through this correlation pressure drop can be calculated from known pores geometry. Since pores geometry can be often obtained from lab experiment or well logging, the new correlation also provides a unique approach to quantify the coefficient of quadratic term in Forchheimer equation. In this study we developed a governing equation through a rigorous theoretical derivation. With this equation the non-Darcy flow coefficient in Forchheimer equation can be calculated. The required input data for the new equation are readily obtained from well log interpretation. The new equation is a powerful tool in the event of no experimental measured non-Darcy flow coefficient available. It eliminates the errors or the arbitrary content in the empirical correlations.
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Using a Novel Spacer and Ultralow Density Cement System to Control Lost Circulation in Coalbed Methane (CBM) Wells
More LessCoalbed methane (CBM) is one of the major clean-burning gas resources. Development and utilization of CBM can increase the energy supply, improve coal mine safety, and protect the global environment. The southern Qinshui basin of China is rich in coalbed methane; it is the first area that obtained good results in the commercial development of CBM in China. However, lost circulation is a common problem during cementing through the fractured coal-seams known as cleats. These cleats form an interconnected fracture network and this allows cement slurry to loss through the coal-seams during cementing operations. Cleats are often wide enough to accept cement slurry, not just cement slurry filtrate. Hence, simply reducing slurry density does not ensure a good cement job. Preventing cement slurry loss to coal-seams while cementing production casing is a major challenge. To solve lost circulation problem across coal formations, an innovative hydrophilic-fiber-based spacer fluid and ultralow density cement slurries with density of 0.95-1.20 g/cm3 have been formulated. Laboratory tests have verified the effectiveness of hydrophilic-fiber-based spacer fluid in plugging these cleats of coal-seams. The ultralow density cement slurries exhibite favorable properties. These test results are confirmed by the good field application results obtained in southern Qinshui basin. Fourteen CBM wells have been successfully cemented using the novel spacer fluid and the ultralow density cement slurries. The combined application of the hydrophilic-fiber-based spacer fluid and the ultralow density cement slurry system is able to successfully combate the lost circulation problem in CBM wells, and provides better zonal isolation as well. This paper provides details about the slurry design and field application, and also presents the cement bond evaluations that verify the conclusions.
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Assessing Unconventional Resources Using an Integrated Petroleum Systems Approach
Authors A. Shankar Roy, Alexander Neber and Zailani Abdul KadirPetroleum system modeling has matured in the past few years and is now a valuable component in conventional exploration. It has become best practice to mitigate risks by using petroleum system modeling to predict the presence, types, and volumes of hydrocarbons in prospective areas or structures before drilling. An adaptation of this methodology has been successfully applied to unconventional resource plays. Petroleum system modeling may be applied to predict: the type and quantity of hydrocarbon remaining in the source rock, proportion of adsorbed gas, porosity, and geomechanical properties of potential unconventional reservoirs. A new methodology has been developed to integrate trap, reservoir, charge, seal, and other risk (sub-) elements to evaluate play risk. Chance-of-success (COS) maps are created by transforming the physical propertiy maps to maps with probability units. As data, interpretations and related COS maps are in the same software system, the evaluation can be kept alive and dynamic as new data interpretations become available. Within the same application, prospect COS can be evaluated using a consistent approach This paper illustrates this methodology using examples from shale plays in North America, data-rich plays from the North Slope of Alaska and data-poor plays that are more representative of many Asia-Pacific basins from the north-eastern and southern regions of the United States. The examples demonstrate the application of the methodology in both frontier and mature areas, either in quick data-room reviews or for delineating prospects.
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Hawiyah Gas Plant Alarm Rationalization and Controller Performance Monitoring
More LessIn order to improve the plant and operation efficiency and reliability, HGP established a consistent and standard methodology for the development, implementation, and modification of process and system alarms. In addition, this methodology serves as guideline to monitor, fix and report bad actors in alarms and PID controllers. The task involves a comprehensive study to the entire plant alarms database including settings, grouping, priorities, philosophy and configuration. In addition, this task will ensure the continuity of PID controllers monitoring to ensure that all of the plant PID controllers are in auto and they are maintaining their set point. Succeeding to achieve this will ensure the optimum performance and efficiency and ensure more vigilant operation. HGP succeeded to bring the controller in auto to above 90% and a full alarms rationalization study was conducted to bring the alarms level to the international KPIs. The paper will start with providing basic background about essential definition including the alarms, alarm rationalization and controller performance monitoring. Thin, the paper will address the importance of the subject and the need of the improvement. As there are many recent studies indicates that missing critical alarms lead to fatal insidents and major damages to different facilities. In addition, many of the plants upset and changes could have been avoided if good alarming system is in place. Beside all of this, the paper will address the importance of the plant controllers’ automation as having these valves on auto will assure having the targeted product with the best possible efficiency.
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Successful Implementation of Fiber-Laden Fluid for Hydraulic Fracturing of Jurassic Formations in Western Siberia
Authors R. Kayumov, Aleksey Borisenko, Olesya Levanyuk, Irina Savelyeva and Sergey EmelyanovThe Urnenskoe field is located in the Tyumen region, Western Siberia. The main production target is the J1 formation belonging to the upper Jurassic Vasyugansk suite. Subsurface geology of the Urnenskoe field features the lithological heterogeneity of the J1 formation with high- and low-permeability interlayers and considerable petroleum reserves in upper low-permeability formation intervals. Oil and water have highly different viscosities permitting rapid water breakthrough into the formation. The first hydraulic fracturing operations were carried out at the Urnenskoe field in 2010. Because there are rich oilsaturated zones in the low-permeability upper zone of the reservoir, the properties of the fracturing fluid to transport proppant and its ability to prevent settling during both the pumping and when the fracture is closing are decisive for the well productivity after the fracturing operation. Fracturing fluid with degradable fibers was selected to achieve these properties during hydraulic fracturing. The fibers create a reinforcing net within the fracturing fluid with proppant and mechanically assist the transportation and suspension of the proppant grains. The temperature decomposes the fibers when the fracture is closed. In addition, the fibers allow lowering the polymer concentration in the fracturing fluid, thus enabling control of the fracture vertical growth and decreasing proppant pack damage. Since there are no all-season roads and it is difficult to approach the Urnenskoe field in the summer, there was no fracturing fleet capable of performing an operation utilizing the fluid with degradable fibers in July 2011. Therefore, 7 conventional fracturing operations were performed; these can be used to compare the effectiveness of conventional fracturing with another 23 operations in which the fibers were used. These operations revealed that the wells in which the fibers were used had a dimensionless productivity index that was 33% higher, and this effect remained stable. Also, for the wells with the fiber application, the average cumulative oil production for 5 months was 2,245 tons higher (recalculated for one well). These results confirm the effectiveness of hydraulic fracturing with degradable fibers in the Urnenskoe field. The successful experience of using hydraulic fracturing with degradable fibers at the Urnenskoe field, laboratory tests of the fiber-laden fluid, analysis of well productivity, and particular applications of the technology provide information to guide further optimization. In addition, the technology has been applied in the Jurassic formations of the neighboring Ust-Tegusskoe field, where a considerable productivity gain was achieved compared with the conventional fracturing operations.
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Mitigation of Deepwater Shallow Hazards with Simplified Cement System: South China Sea Case Study
Authors T.B. Ellis, E. Paul and R. AcordaCementing is one of the most critical steps in the well construction phase. Qualified cement integrity is considered a barrier to inhibit fluid migration to surface. For conventional wells, cement in addition to barriers such as BOPs (Blow Out Preventers), fluid hydrostatic pressure, and mechanical methods are used to ensure fluid migration is inhibited. For top-hole sections of deepwater exploration wells however, cementing is your only barrier to mitigate uncontrolled fluid flow to the seabed. During the top-hole operations (typically 36-in. and 26-in. hole sections), the bore hole is drilled without a riser and returns are taken to seabed. This creates difficultly in controlling shallow hazards such as gas hydrates and shallow water flow because the well cannot be killed using conventional methods. To assure mitigation of shallow hazards, an emphasis is made on achieving short transition times for cement designs. For South China Sea operations, it is common practice to incorporate cenospheres (dry blended lightweight additive) into the cement design to ensure suitable properties are achieved. However, the use of cenospheres requires blending onshore and excess blends to be shipped offshore for contingency purposes. Although required slurry properties can be achieved with cenospheres; logistical issues, left over disposal concerns, costs, and low cenosphere pressure ratings create a complex operation. In addition, cement systems should be designed to incorporate loss of lightweight material during transfer offshore, and must account for higher down-hole densities due to crushing of lightweight cenospheres. All of these processes require great emphasis on Quality Assurance / Quality Control (QA/QC) and economic concessions. Other unique challenges that must be accounted for are low temperatures, commonly around 4°C (50° F) at seabed, low fracture gradients, enlarged hole sizes due to high rate of penetration (ROP) drilling, and environmental regulations due to returns at seabed. The cement system must be designed for all the above aspects, and still maintain excellent integrity to enable the BOP stack to be installed upon a firm foundation. This study will describe a new simplified cement system which exhibits excellent slurry properties necessary for a deepwater environment. Laboratory results and engineering procedures will be reviewed to demonstrate that all necessary qualities for mitigation of shallow hazards are met. Furthermore, logistical and HSE advantages will be highlighted, and two case histories will be discussed.
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Dual Function Reverse Demulsifier and Demulsifier for the Improvement of Polymer Flooding Produced Water Treatment
More LessAdding partially hydrolyzed polyacrylamide (HPAM) to flood water for enhanced oil recovery has resulted in some difficulties for treatment and re-injection of produced water at Daqing Oilfield of China: Production of the injected HPAM increased water phase viscosity and emulsification of the produced fluid, leading to more oil carry-over; The state-of-art cationic water clarifiers showed poor compatibility with HPAM containing produced water due to formation of very sticky oily flocs which seriously pollutes bed filters and slop oil recovered in produced water treatment. Throughputs of existent produced water treatment facilities had to be lowered by up to 50% so that the HPAM containing produced water might be treated to re-injection specifications. As an alternative for the state-of-art cationic water clarifier, a nonionic reverse demulsifier and demulsifier consisting of both water soluble and oil soluble active components respectively for water clarification and water-in-oil emulsion breaking, was developed as a water dispersible micro-emulsion mixture. Injected into high water-cut o/w produced fluid prior to the initial oil/water separation, the dual function chemical greatly enhanced flocculation and coalescence of the oil droplets in the reverse crude oil emulsion while maintaining adequate emulsion breaking capability for downstream crude oil dehydration, leading to less oil carry-over and looser emulsion in the influent water of produced water treatment facilities. In one field application, injected at a dosage of 15mg/L into the polymer flooding produced reverse crude oil emulsion upstream of oil/water separation, the dual function chemical reduced the oil content in the influent water of a produced water treatment facility from 2004mg/L to 443mg/L, and lowered the oil content in the effluent water of bed filters from 31mg/L to 4.1mg/L without application of water clarifiers.
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Formation Damage and Treatment of Offshore Water Disposal Wells in Saudi Arabia: Case Studies
Authors K. Mei, H. B. Qahtani, A. S. Al-Kuait and L. A. SukkarIn one Saudi Aramco offshore oil field, the formation fluids are being produced from different platforms and transported to one onshore gas-oil separation plant (GOSP) where the produced water is removed from the hydrocarbon stream. The produced water is injected back to highly permeable formations through disposal wells with no interruption. In this way, the water disposal system is an integral part of the hydrocarbon recovery system. A failure of one of the disposal wells could adversely affect oil production. Saudi Aramco petroleum engineers are placing more and more attention on water disposal wells as a higher volume of produced water from the increasing hydrocarbon production rates has to be disposed of continuously every day. The primary objective of surveillance on the disposal wells is to keep an extra disposal capacity for continuous oil production from the field and to precisely monitor the decline rate of the capacity of each disposal well. A real sweep efficiency and pressure maintenance are not the surveillance scope for water disposal wells in our case. Few technical papers have been published that discuss the problems a water disposal system may have in a matured field and address issues such as surveillance of well performance and water quality, formation damage mechanisms, treatment and so forth. In this paper, the existing water disposal system in a matured offshore oil field is briefly described and discussed with the surveillance of well performance and the quality disposal water, potential problems, and the evolution of the surveillance philosophy. The reasons why most disposal wells experienced severe injection decline are analyzed and discussed in detail. Historic treatments were summarized with actual outputs demonstrating “ineffective” treatments for the issues discussed. After several trial tests, one customized chemical treatment recipe was developed to effectively tackle the issues and actual well data is included showing the effectiveness of those treatments. A new surveillance strategy for better monitoring of well performance and the quality of “waste” fluid is also discussed in this paper. It can be concluded from our work that formation damage exists extensively in wastewater injection wells and that it greatly influences the performance of disposal wells. Any treatment for restoring the injection capacity of water disposal wells impaired by low quality water is expensive. Any successful treatment is rooted into the detailed analysis of the problems. Implementation of a proper surveillance program and appropriate processing of the injection fluid is also vitally important for wastewater management.
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Boiler Reliability Study – Abqaiq Plant Experience
Authors S. A. Al-Amoudi, Mohammad H. Al-Hajji and Mohammad S. Al-SuwaianThis paper describes a reliability enhancement study for boilers that was recently conducted at the world’s largest crude oil stabilization plant in Abqaiq, Saudi Arabia. Since its inception in the 1940s, the Abqaiq plant has had to operate a number of water tube boilers to produce high pressure steam that is used to process stabilized oil. In each boiler, there are more than 2,000 tubes and, over the years, several boiler tube failures have occurred. This paper describes a recent study that was conducted to evaluate the history of tubes failure, identify the main factors of the tube failures, and generate recommendations to minimize the number of failures. This paper presents the results of a recent boiler life assessment study that was conducted on one of the boilers at the Abqaiq plant.
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Harnessing Intelligent Field Capabilities for Early Understanding of Reservoir Behavior and Proactive Decisions
Authors Amer H. Abuhassoun and Sultan S. ShamraniWith recent advancements in field instrumentation technologies and the expansion of Saudi Aramco’s state-of-the-art intelligent field infrastructure, a wealth of valuable knowledge is being derived from integrating intelligent field capabilities with best-in-class reservoir management practices. Intelligent field applications have already leveraged real-time reservoir surveillance data to enable timely responses and fast interventions for events observed from real-time data. As richer and more granular datasets are collected from the field, deeper insights and understanding of the reservoirs are gained at fractions of the needed time where intelligent field capabilities are not present. The abundance and timely processing of intelligent field data enables more tactical adjustments in reservoir management strategy. This type of real-time reservoir management has already shown great value in reservoir performance optimization. This paper discusses several cases in which an intelligent field enabled early detection of anomalies and shortened the timecycle for an analysis, decision and action. The first case discusses the early detection of localized pressure support anomalies due to poor rock quality. This timely detection, facilitated by intelligent field infrastructure, enabled quick decision making and actions to overcome the anomaly. The second case shows how real-time monitoring of reservoir pressure propagation has helped to detect over-injection in two injectors with malfunctioned meters. This has allowed timely action to ensure uniform pressure propagation and repair of faulty equipment. The third case shows that the utilization of real-time data has assisted in detecting a casing leak in a short time, which helped in making a corrective action to restore the well’s capacity. In all three cases, had an intelligent field not been there, the time-cycle from detection to analysis, and to decision and action, would have been substantially longer, resulting in higher operational costs and an impact on reservoir performance.
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Influence of Micro-Computed Tomography Image Resolution on the Predictions of Petrophysical Properties
Micro-CT scanning is a non-destructive technique that can provide three-dimensional images of rock pore space at a resolution of a few microns. . However, these greyscale images cannot be directly input into simulators to predict flow properties; they require image processing to segment the solid and void space in the rock. Dynamic and static single phase properties can then be computed using the images directly or on extracted equivalent network models. In this paper, we study the effect of imaging resolution (five different voxel sizes ranging from 6-20 μm) of Clashach and Doddington sandstone on predicted single phase properties (porosity and absolute permeability) and network properties. Experimental data is used to validate the predictions. The results suggest that the computed porosity was largely independent of resolution and in good agreement with the measured value, while image resolutions of a few microns are sufficient to determine the permeability of a high-permeability rock such as Doddington but may not be sufficient for lower permeability samples. The topologically representative networks are sensitive to resolution, adding additional smaller pores and throats as the resolution is increased. This latter reason was confirmed by a network extraction analysis that indicated the average throat radius was 6 m, similar to the highest resolution used and insufficient to image all important features of the pore space properly.
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Calculations of Equivalent Circulating Density in Underbalanced Drilling Operation
More LessUnderbalanced drilling using gasified fluids is one of the most widely used methods to drill depleted, low pressure and highly fractured formations. For ensuring a safe and successful underbalanced drilling operation, accurate prediction of the equivalent circulating density (ECD) is very important. Nevertheless, estimating ECD of gasified fluids is not easy due to the complexity of the two-phase fluid flow inside the wellbore. In this study, there are two major focuses considered; i) validation of the accuracy of Beggs & Brill (1973) model on the prediction of pressure losses of gasified fluids in underbalanced drilling operation, and modification of Beggs & Brill (1973) model for pressure loss estimation inside the wellbore, and ii) to propose an ECD calculation procedure for gasified fluids by using modified Beggs & Brill (1973) model. To validate the accuracy of Beggs & Brill (1973) model, experiments were carried out using Middle East Technical University (METU) Cuttings Transport Facility to obtain the pressure losses of gasified fluids in an annulus and their corresponding flow patterns. Air-water mixtures were used with various in-situ air and water flow velocities of 0-120 ft/s and 0-10 ft/s, respectively, at wellbore inclinations of 90°, 75°, 60°, 45° and 12.5° without inner pipe rotation. Pressures were recorded at several points along the annular test section, and pressure distribution along the test section was measured. Meanwhile, flow patterns were determined by the help of a high speed digital camera. Results showed that although Beggs & Brill (1973) model can estimate pressure losses in low gas and liquid flow rates and low slip ratio between two phases for horizontal and near horizontal annular sections with a reasonable accuracy, this model cannot accurately calculate pressure losses at inclined and vertical annular sections. With some modifications, improved Beggs & Brill (1973) model (by applying suggested procedure) can be used to predict ECD and annular pressure losses of gasified fluids inside the annulus accurately. This information can be directly applied for underbalanced drilling operations when gasified fluids are used.
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Performance of Re-Fracturing in Multiple Thin Layers of Low Permeability Oilfields
Authors Liu He and Wang WenjunFor the low permeability formation of Daqing oilfield, we have to stimulate the multiple thin layers in one stage during a separated layer fracturing job because there are many of layers in one well. Based on the logging data analysis, the hard fracturing layers identified method has been built for the multiple thin layers re-fracturing in low permeability layers in Daqing. According to the calculating result of the broken pressure difference within multiple layers, we can recognize the layer which is not been stimulated in the first time multiple layers limited entry fracturing job. We can optimize the fracturing parameters design in the re-fracturing treatment. Based on the research of interference disciplinarian between fractures, we can get the boundary of the least interval without the interference. So we can analysis which layer is not been stimulated enough because of fractures interference in the first time fracturing. Researching the relationship of perforation holes erosion with fracturing treatment parameters can help us to estimate the first time fracturing and optimize the re-fracturing treatment parameters designing. By using above method, we have got a satisfactory re-fracturing result in 27 wells. After fracturing, the oil production is increased 6.8t/d and the water ratio is decreased 4.2%. The oil production is even higher 1.2t/d than the first time fracturing. That shows the new layers have been stimulated.
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Classification and Evaluation of Ultra-Low Permeability Reservoirs in the Changqing Oilfield
Authors Xinquan Ran, Anqi Li, Jiyong Zhao and Shuheng LiWith the rapid development of the world economy, the exploration and development of unconventional oil and gas resources have become a new hot spot. As an important subset of unconventional reservoirs, ultra-low permeability (ULP) reservoirs have been greatly concerned. Studies suggest that the ultra-low permeability reservoir belongs to the typical tight reservoir. The current low-permeability reservoir classification criteria available in the literature cannot meet the actual needs of ultralow permeability reservoir development. Through researches, reservoir characterization parameters of effective porosity, mainstream throat radius, movable fluid saturation and starting pressure gradient are screened out to build quaternary classification coefficient. A new standard of classification and evaluation of ultra-low permeability reservoirs is established, and ultra-low permeability reservoirs are divided into three categories. Thus it provides a theoretical basis for speeding up the effective development of ultra-low permeability reservoirs. Keywords: unconventional oil and gas; tight oil; ultra-low permeability reservoir; characterization parameter; classification and evaluation Since the beginning of the 21st century, the world economy has entered a new cycle of development. The demand for oil and gas resources in the countries soared. Facing the huge demand for energy, productivity construction and production rate are relatively insufficient throughout the world. Unconventional oil and gas resources are beginning to receive more attention. Ultra-low permeability reservoirs, as important unconventional oil and gas reservoirs, have huge potential for exploration and development, but the current classification of reservoir evaluation criteria cannot meet the needs of ultra-low permeability reservoir exploration and development. In order to effectively guide the exploration and development practice of ultra-low permeability reservoirs, it is of great significance to launch researches on ultra-low permeability reservoir characterization parameter system, and to establish a new classification and evaluation criteria.
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Employing First Principles Model-Based Soft Sensors for Superior Process Control and Optimization
Authors Shuyee D. Lee and Aidhah J. ZahraniThis paper describes the development and implementation of soft sensors at the world’s largest crude oil stabilization plant (Abqaiq) for superior process control and optimization. The soft sensor uses a rigorous steady-state model combined with dynamic synchronization to compute real-time stream properties (i.e., hydrogen sulfide amount (H2S), Reid vapor pressure (RVP), and true vapor pressure (TVP)) so corrective action can be taken immediately. Crude oil is characterized by 19 pure light components and 17 heavy pseudo-components. A non-Random Two-Liquid (NRTL) model is used for predicting thermodynamic properties of the liquid phase while an ideal gas model is used for the vapor phase. Unlike traditional data driven methods, the soft sensor adopts the first-principles modeling approach so current operating conditions can be correctly reflected in the online model based on sound engineering principles. Fault detection, sensor validation, and calibration with laboratory data are also performed online to ensure reliable and accurate predicted H2S, RVP and TVP values.
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SMS Skyscrapers
Authors Jamal Khan and Gary AmidenauThis paper offers methodology, guidelines and tools to assist Oil/ Gas plants and other industrial facilities to develop organize and improve local safety programs (SMS) that comply with corporate elements of safety management as in the 11 elements of the “Saudi Aramco Safety Management System”. The development is done through a consistent method and format for writing the system elements and its processes. For simplicity, the model is represented by a Skyscraper building “SMS Skyscraper”. All model processes include definition of crucial characteristics which are: Purpose, Applicability, Description, Flowcharts, Responsibilities, Training, Performance Indicators, Supporting Tools, Documentation and References. Once the model is used, it helps achieve and sustain quality in defining HSE processes. The quality of processes drive quality in execution of safety activities. This in turn paves the path for proper identification Hazards and evaluation Risk every addition to improving the accountability culture. The overall objective is to help organizations develop customized “Safety Management Systems” that capture the knowledge and “know-how” in addition to providing tools that foster world class execution. In time, and with the right leadership, this will transform organizational and community safety culture and consequently reduce incidents ON and OFF the Job. The “SMS Skyscraper” model has been used to develop 100 Safety Management Processes for Khursaniyah Gas Plant Safety Management System (KGP SMS) in the period between February 2009 to March 2010 and is now available on Saudi Aramco intranet portal at http://KGP/SMS. The model has helped Khursaniyah Gas Plant achieve level of ownership of our local SMS in addition to placing the department on the leading edge of safety management in Saudi Aramco. It also helped young individuals in the organization substantially grow their knowledge in safety management. The model has been reviewed and acknowledged by a handful of safety professionals. It has also been recognized by the Upstream business line in Saudi Aramco as the “go-by” model for development of safety processes. Many other departments in Saudi Aramco are now moving towards the Skyscraper model for comprehensive development of local SMS processes.
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Assessment of Corrosion and Mechanical Properties Degradation of Pipeline Steel After Long Term Service in High Sour Gas-Field Environments
Authors Cheng Zhang, Qingsheng Zhang, Weiguo Chen, Dexu Liu, Tiongxiong Ou, Xuesong Huang, Can Chen and Changfeng ChenIn this work, the corrosion behavior and mechanical degradation of two types of pipe steel, Inconoy 825 and L360, after two years of high sour environments service in Puguang gas-field were studied. Results demonstrated that a fearful elemental sulfur layer deposited on the inner wall of pipeline, pitting corrosion and hydrogen-induced cracking was observed in L360 pipe. In comparison, no pitting corrosion and hydrogen-induced cracking was found in Inconoy 825 steel pipe due to its excellent resistance to corrosion. Furthermore, mechanical properties (yield strength, impact strength, elongation, hardness, fracture toughness) and stress corrosion cracking were investigated. Results showed that the yield strength decreased obviously and the percentage of elongation increased in Inconoy 825 steel but little change in L360. The analysis a change of the mentioned mechanical characteristics together with the results of the diffusion and tapping of hydrogen of them indicated that the properties degradation of Inconoy 825 pipeline steel after long term service was associated with essential role of hydrogen in these processes. The consequences of sudden failures and severe corrosion of metallic material in the high sour gas-field, which associated with their exposure to H2S/CO2 containing gas, led to the preparation of evaluation tests of pipeline. However, passing evaluation tests cannot guarantee the safety in actual work condition unless the field experience had been at least two years. As the first attempt to exploit high sour gas-field in China, it is anticipated that this work of Puguang provides valuable data and an essential insight into the corrosion and degradation of pipeline steel services in high-sour environmental.
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Integrating an LNG Plant with an Unconventional Gas Supply
Authors Chris Langley and Adriaan SpaanderArrow Energy is a JV company based in Brisbane, Australia, that is owned 50/50 by the Shell group and PetroChina (a subsidiary of CNPC). Arrow is planning to develop its tenement holdings of Coal Seam Gas (CSG) in the Surat and Bowen Basins of central Queensland. The CSG will be produced at very low pressures from shallow wells, gathered and compressed into two 500 km trunk-lines for delivery to a two train LNG plant, with each train sized at 4.0 mtpa capacity. The LNG plant will be located on Curtis Island, opposite Gladstone harbour, in Queensland. CSG is classed as “unconventional” gas; this is the first time that Shell or PetroChina have designed an LNG plant with an unconventional gas feed. The paper discusses the unique aspects of integrating an LNG plant with this unconventional gas feed.
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Production Optimization with Hydraulic Fracturing: Application of Fluid Technology to Control Fracture Height Growth in Deep Hard-Rock Formation
Authors Mohammad Al-Dhamen, Areiyando Makmun and Ahmed HilalHydraulic fracturing is frequently used to create the reservoir-wellbore connectivity required to produce the hydrocarbon from tight formations. Many factors can be considered as risks to the success of operations. One arises in reservoirs with a water-bearing zone in close proximity to the net pay. Many times, the risk of fracture growth into the water zone limits the stimulation options and eliminates the option of a hydraulic fracturing treatment, thereby constraining the well’s future production. The challenges increase when the reservoirs are deep, hot, and exhibit a high Young’s modulus. Under these conditions, it greatly increases the risk of an early screenout, and the introduction of fracturing fluid into the formation before a high-conductivity proppant pack is fully placed will damage the formation and hinder production. In Saudi Arabia, a well in a relatively new field encompassed all three challenging characteristics. The target reservoir section was between two water-bearing zones, had high bottomhole temperature, and high Young’s modulus. Traditional polymer-based crosslinked fluids would address the challenges from the perspective of proppant placement. However, these thick crosslinked fluids would also risk in uncontrolled fracture growth into the water zones. A polymer-free, high-temperature viscoelastic surfactant (VES) fracturing fluid was used to balance the risks of incomplete proppant placement, formation damage, and fracture growth that would result in water production. The VES fluid selected for treatment of Well SH-3 has a low viscosity compared to that of a traditional crosslinked fluid; it therefore generates less net pressure and thus lowers the risk of the fracture growing into the water zones. It also has excellent capacity to carry and suspend proppant. To increase its efficiency, the VES fluid was further enhanced by using a degradable fluid-loss additive. Pumped on a conservative schedule, the hydraulic fracturing treatment placed 61,500 lbm of proppant into the thin reservoir section between two water-bearing zones without any operational issues. The Minifrac analysis, stress profile calculation, and fracture geometry characterization, as well as no water production, has confirmed the controlled fracture height growth. Furthermore, pre- and post-stimulation analyses validated the improved productivity, giving a successful stimulation option for the development of this field.
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Mitigating Challenges in Resolving 7” Liner Leak- Case Study
Authors Husain Al Muailu, Konstantinos Zorbalas, Karam Al Yateem and Javier GarciaAn evaluation process was conducted in assessing various solutions towards remedial action to a 7” liner with an identified leak in a water injector well. The leak to the 7” liner was identified through pressure testing of the well. A comprehensive investigation and analysis was performed to identify the liner condition, exact leak location and the extent of the leak. It was accomplished by analyzing all previous activities performed during the life of the well and through running special pressure testing as well as logging the well with ultrasonic and physical logs. The problem identification and proposed solutions were focused on curing the leak and bringing the well back on injection with the least operational risk and highest possibility of success. Corrosion and cement bond logs were ran and showed a better picture in regards to the extent of the corroded section and the quality of cement behind it. A caliber log was also run in the open hole which showed a washed out area near the 7” liner shoe. Several solutions that could repair the 7” liner leak were assessed including: i) cement squeeze in the leak zone, ii) setting an off bottom 4.5” liner and iii) using a 5.5” expandable liner. The evaluation process included each solution’s impact on the future injectivity of the well, the effectiveness of each option, operational challenges and associated risks. Moreover, nodal analysis was performed to evaluate possible reduction of the injection rate associated with each solution. The final decision to repair the leak was to run an expandable liner and it was based on its advantages and deployment challenges. Lessons learned from this operation included the methods used to identify and assess the damage of the casing leak. Proper preparation and cleanout of the corroded section and the operation procedures performed to expand the liner are summarized in this paper.
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Raising Upstream Digital Professionals' Competency and Productivity Using Performance-Based Training
Authors Kenneth K. Lau and Nashid AbdulkhaaliqSaudi Aramco has established the Upstream Professional Development Center (UPDC) to train its geoscientists and engineers to independently and proficiently conduct a wide range of exploration and production operations and its systems analysts in providing a collaborative environment for executing these operations. Its purpose is not to replace academic institutions but rather to complement them by introducing activity and performance-based training (PBT) programs. The objective is not only to improve the organization‘s overall performance level but to raise the standards of its entire workforce as well. This paper describes how UPDC‘s Upstream Computing job family designs, develops and delivers its courses for recently hired Upstream digital professionals (computer scientists and software engineers). It outlines how to effectively train them to acquire a fundamental understanding of a wide range of oil and gas exploration and production (Upstream) operations and to use this knowledge to support, maintain and develop an equally wide range of software applications used for facilitating everyday Upstream operations. Saudi Aramco‘s systems analysts are loaned by their line organizations to UPDC to design and implement these courses based on their work experiences and best practices. To teach and/or re-enforce technical concepts, and for employees to gain appreciation of these practices, over 50% of class time is devoted to activities, assessments, reviews and discussions. For the advancement of mid-career digital professionals, performance-based curriculums (identified by Saudi Aramco as ―career professional curriculums‖) are also being developed. An overview on how these curriculums are designed based on job outcome requirements will be outlined. UPDC instructors use advanced audiovisual, animation and simulation technologies for effective course delivery and promoting in-class activity participation.
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Achieving Brazilian Extended Reach Drilling Records on Polvo Project with Ultra-High Torque Connection
Authors Nathan Biddle, Luciana Osório, Hector Arevalo, Marcelo Velho, Vincent Flores and Scott GrangerThe Polvo project is a platform based drilling rig located ~95km off the Brazilian coast in the Campos Basin. The field consists of two distinct reservoirs, a carbonate reservoir to the southwest, and a sandstone reservoir to the east. The Polvo project began drilling in March 2007 and has since drilled a total of 32 wellbores. The wells range in difficulty from “short reach” to “very extended reach” wellbores. The deviation is from 3-7º DLS at angles of 30-92º. Wellbores are 3-dimensionally designed in order to improve total reservoir exposure. Extended reach, deep and high deviation wells require the use of a drill string that has both higher torsional yield strength drill pipe body and greater torque capacity tool joints than are afforded by standard API connections. VAM Express double shoulder connection has been designed in order to address the drilling challenges linked to the development of such complex wells. This proprietary high torque connection incorporates four major design features allowing pushing further the drilling envelope limits: quick rig make-up, high torque performance, user friendly and durability. After beginning the project and platform placement, it was discovered that sandstone reservoir targets further to the east had higher productivity than expected. After drilling 12 wells and numerous lessons learned, the furthest extended reach well in the history of Brazil was attempted and successfully completed. The Pol-O wellbore was drilled to a total measured depth of 6,489 m (2,429 m TVD) and a vertical section step out of 5,615 m. This wellbore was and continues to hold the record for furthest reach wellbore in the history of Brazil. In addition to obtaining this extended reach record, Polvo also attained the record of fastest 24 hours drilling in an 8 ½” hole with 1,610 m in 24 hours. To obtain this drilling record, it was not only critical to have high on bottom ROP, but also to optimize connection time. The high torque connection helped to achieve this fast connection time and also prevented any drillstring failure. Having drilled over 100,000m of total hole in highly deviated wellbores using the same drillstring, there has not been any twist-offs or back-offs on the Polvo project. By being able to drill these further reach wellbores successfully and more economically, the Polvo Platform has proved up further reserves that can be produced without requiring installation of another platform or subsea tiebacks. The rig is not limited by connection strength and plans are in place to improve the top-drive to deliver more torque, while staying with the same double shoulder connection size.
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Hydraulic Fracturing Candidate-Well Selection by Interval Type-2 Fuzzy Set and System
Authors Mansoor Zoveidavianpoor, Ariffin Samsuri and Seyed Reza ShadizadehSelecting a target formation(s) among a vast numbers of zones/sub-layers within huge numbers of hydrocarbon producing wells in a reservoir, is considered a difficult task, particularly if the selection goes through a group of parameters having different attributes and features; such as geological aspect, reservoir and fluid characteristics, etc. The trend of candidate-well selection (CWS) process for Hydraulic Fracturing (HF) had recognized to be complex, nonlinear, un-equilibrium, and adherent with uncertainty. Interval Type-2 Fuzzy Logic and Systems (IT2-FLSs) are very useful in circumstances where it is difficult to determine an exact membership function (MF) for a Fuzzy Set (FS); hence they are very effective for dealing with uncertainties. Classical FLS which called T1-FLS is not capable of fully capturing the linguistic and numerical uncertainties in the terms used and the inconsistency of the expert's decision-making. Therefore, the need arises to use a method that could handle uncertainties. The procedure of applying this novel study in the area of HF CWS, will have illustrated through a case study in a carbonate reservoir. The utilization of a modern and right problem-solving tool such as T2-FSS should be considered a great concern to the petroleum industry. Although sizeable clarity has been achieved in this area, no conceptualization such as dealing with uncertainty, has yet answered by the previous studies. New requirements force the previous methods to advance and novel techniques expected to meet the requirements and remove the existing weakness. In highlighting this need, the question has been answered about why IT2-FLSs should be used in this study. Also, its advantages over T1-FLS will be illustrated. This paper critically assesses the importance of the proposed methodology to develop a reliable model of HF CWS. This investigation is the first research which applied such a cutting-edge approach and tries to fill the gap between recent developments in uncertainty management through utilization of IT2-FLSs in HF candidate-well selection.
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A Case Study: Innovative Open Hole Well Completion Provides Superior Results in Tight Gas Formation in Jilin District, China
Authors Wang Feng, Changyu Liu, Yingan Zhang, Yong Wang, Hai Liu and Ka Tong KuDrilling of horizontal wells has increased steadily over the last few years in China on land. As technology has developed, operators have seen the economic and production benefits of drilling horizontally 1, 2. In the Changling gas field, the Deng Louku formations are primarily low porosity (average 5.2%) and low permeability (average 0.17md) tight sand. Typically, wells in this area are drilled vertically and completed with cemented casing. Proppant fracturing was necessary to produce the well economically due to the low permeability nature of the formation. However the production results from the conventional vertical fracturing completions were not very promising and most of the wells experienced rapid production decline once they were put on production. Thus it became crucial to find an engineering solution to effectively unlock the reserves and obtain sustained long term productivity. Multistage fracturing of the DP2 horionatal well is a milestone for the operator due to: 1) the deepest, and most stages in a single horizontal well in a tight sand formation in China was completed and fractured; 2) the biggest fracturing job for a single well in terms of proppant and fracture fluid volume was successfully pumped continuously by first time application of the precise continuous mixer (PCM) in China; 3) an innovative multistage fracturing design workflow was developed to optimize the horizontal well completion design including several disciplines: geology, reservoir modeling and fracturing. This workflow was set as the standard design process for multistage fracturing design in the field. The DP2 horizontal well was completed in ten stages in the 837 m openhole section and the ten fracturing stages were pumped continuously in 3 days. The PCM was used to improve the fracturing operation efficiency. A total of 1425 tons of 30/50 proppant was successfully placed into the formation using 4870 m3 fracturing fluid. The well produced 320,000 m3/day initially and was stabilized at 180,000 m3/day with 20 MPa wellhead pressure, which is 5 times higher than the average offset well. The application of real time hydraulic fracturing monitor technology helpped to verify that the optimized fracture half-length was achieved, and to adjust the fracturing schedule in real time for the second stage.
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Drilling of Multilateral Wells Aided with Geochemical Analysis, Kuwait
This paper describes the utilization of Real-Time geochemical analysis to support geosteering of a smart multi-lateral well, located in one of the highest flow potential areas in Kuwait. The Burgan reservoir consists of vertically stacked channel sands along with a fault network connected to the aquifer and contains highly viscous reservoir fluid. This drastically enhances the water mobility, and results in severe premature water breakthrough. Hence, leaves zones of by-passed oil. For optimum reservoir characterization, it was essential to integrate all reservoir-related data from macro to micro scale. X-ray Fluorescence elemental data collected from offset cores were used to predict key rock attributes and calibrated with standard petrophysical logs.The scope was constructing predictive models for the following properties: 1) lithological variations which cannot be captured by other LWD tools 2) detailed mineralogy to determine the diagenetic overprint 3) depositional environment of different Burgan sand facies. XRF elemental analysis while drilling was used to improve borehole positioning, and identify faults in correlation with Image logs. Nature of the fractures/faults, contributing to porosity and communicating with the aquifer, was inferred from XRF-obtained elemental markers. The integrated approach has resulted in successful geosteering and placing the well with maximum reservoir contact. Moreover, XRF elemental markers have been utilized for isolation of faulted and lower reservoir quality zones, splitting up of horizontal sections and optimization nozzle sizes of the ICDs and hence an optimized Smart completion design. X-ray fluorescence analysis on cuttings in Real-Time provides lithological information otherwise not available while drilling. It gives proxies contributing to the identification of faults and reservoir intervals in an otherwise homogeneous sequence. It helps designing the completion string, isolating sections of low quality or potentially producing water.
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Modeling Production and Well Performance Forecasting of Complex Volcanic Reservoir
Authors Liu He, Zhang Yingan, Zou Honglan and Gao YangThe formations of DaQing gas field are mainly volcanic reservoirs which have the characteristics of low permittivity and complex formation structures. Most of these wells need fracturing remodeling to meet the standards of industrial gas stream, and also, the gas productivity tests as well as the pressure recovery tests conducted on these wells are different from other regular gas reservoirs. Considering the nature of the volcanic reservoir, such as dissolution pores, karsts caves, natural fracture development, we built two mathematical models of dissolution pores development and natural fracture development under both of the Darcy flow conditions and Non-Darcy flow conditions separately to predict the production of triple porosity reservoir after gas reservoir well fractures. By using the Laplace transform and numerical inversion, the equation to calculate production of complex volcanic gas wells is obtained. Based on these researches, law of volcanic reservoir productivity is investigated. The theoretical data are compared with the practical data collected from the field operation. The comparison results reveal how the parameter of the fluid volume, proppant indexes, and conductivity of artificial fracturing induced fractures and length of fractures change affect the productivity. The research work reported in this paper provides theoretical support on the optimization method of fractured wells design of volcanic gas reservoir.
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CSEM inversions using the Gauss-Newton method and a model compression scheme
Authors Aria Abubakar, Yun Lin, Maokun Li and Tarek M. HabashyWe present a model compression scheme for improving the efficiency of the regularized Gauss-Newton inversion algorithm for marine controlled-source electromagnetic applications. In this scheme the unknown model parameters (the resistivity distribution) are represented in terms of a basis such as Fourier, cosine, or wavelet. By applying a proper truncation criterion, the model may then be approximated by a reduced number of basis functions, which is usually much less than the number of the model parameters. Furthermore, since the controlled-source electromagnetic measurements have low-resolution, we will show that for inversion it is sufficient to only keep the low-spatial frequency part of the image. This model compression scheme accelerates the computational time as well as reduces the memory usage of the Gauss-Newton method. For demonstration purposes, we show both synthetic and field data inversions. The results show that we are able to significantly reduce the algorithm computational complexity without compromising the quality of the inverted models.
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Optimizing Dehydrators Operation Using Dynamic Adsorption Time
Authors Eisa A. Almakrami and Amr A. GadiMolecular sieve is a solid deiccant widely used in gas plants for dehydrating wet process gases. Compared to other desiccants, molecular sieve can reduce water content in the outlet gas to less than 0.1 ppmv. This is a must requirement for conditioning feed gas to crypogenic applications. On the other hand, Molecular Sieve is generally more expensive and energy exhaustive.
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New Hybrid Bit Exceeds Expectations in Challenging Application in Tarim Field, China
Authors Denise Nicholl, Alexis Garcia, Hector Barocio, Dennis Sha and Mr Zhou JianThe existence of hard, interbedded formations often prove to be very damaging to conventional polycrystalline diamond compact (PDC) fixed cutter bit designs, and as a result, may require additional trips to replace the bit for insert roller cone or impregnated diamond. This can represent significant additional drilling costs for the operator, equating to very high costs per foot if the remaining section to be drilled is short. The challenge is to maintain a low cost per foot, through the use of a bit design which is both durable enough to drill the desired interval, at the best possible penetration rate. This paper describes the development of a new innovative drill bit technology that fuses two existing fixed cutter materials using a unique design philosophy that allows for greater versatility in drilling a wider range of interbedded, difficult to drill lithologies that are not typically drilled entirely with PDC bits. This novel design philosophy includes optimized cutter placement allowing engineered exposure of diamond impregnated mix applied in critical areas of the bit for added durability. This development project was initially targeted for the sub-Saharan region in the Congo, where the existence of a conglomeratic interval at the bottom of the section prevented to reach total depth (TD) with fixed cutter bits, having to end with roller cone insert designs. In its first trial, the new design drilled three times the interval of the best offset with a 34% improvement in rate of penetration (ROP). Applications in different regions of China were soon identified, resulting in a challenge to design for a new hole size with various drive types; the results of which are detailed in this paper.
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Useful Recycling and Safe Disposal Technology of Waste Oil Based Drilling Fluids and Its Application
Authors Shuixiang Xie, Hao Deng, Rongsha Wang, Yong Yue, Baichun Wu, Guangquan Liu and Yu XuWaste oil-based drilling fluids are hazardous wastes containing oil, heavy-metal and organic pollutants. However, the common treatment methods at home and abroad these methods not only waste many useful resources (because the oil is discarded rather than recovered) but also increase the pro-environment cost of oil companies. This paper develops useful recycling and safe disposal technology of waste oil-based drilling fluids from the perspective of utility, efficiency and economy, which not only recycle useful oil but also reuse and dispose of the rest of mud and waste drilling fluids. The rate of recovery is greater than 90%, and the quality of the recycled oil is very good and meets the requirement of -10 # diesel of cars in GB/T 19147-2003. The concentrations of oil, COD (chemical oxygen demand) and heavy metals in liquid of the processed mud are lower than the secondary standard number in GB8978-1996. The treated wastewater meets the requirements of sewage comprehensive emission.
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A Comprehensive Formation Evaluation Method to Make the Fracturing Decision: A Real Case Analysis from a Low Permeability Formation in Jungger Basin of China
Authors Ben-Cheng Wang, Ren-Shi Nie, Jiang-Wen Xu, Sao-Bo Wei, Guang-Wen Hu, Jun-Ming Zhang and Meng FengLow permeability formation is the main exploration objective in China. Too much misjudgments of fracturing operation would tremendously increase the cost of exploration. We studied a method to estimate the well productivity for a Permian low permeability formation in Junggar Basin of China. Firstly, we made a statistical analysis to the lithology according to logging data and divided the lithology into 7 categories. We developed a set of standards to mark the seven categories. Secondly, we made a statistical analysis to 6 parameters of physical properties, such as porosity, permeability. We also developed a set of standards to mark the physical properties. Thirdly, we made a statistical analysis to DST data and divided the log-log curves of DST into 5 categories. We defined a pressure recovery rate that can reflect the formation energy status and analyzed the characteristics of the pressure recovery rate for different category DST curves. We marked the 5 categories DST curves and its pressure recovery rate. Fourthly, we made a mathematical statistics to the relationships of fracturing productivity with static and dynamic parameters, including pressure recovery rate, sand volume and fluid volume of fracturing. We obtained the productivity prediction equations by using multiple nonlinear regressions to static and dynamic parameters. Fifthly, we needed to use the method of the above 4 steps to mark the lithology, physical properties and DST of a new well and estimate productivity. Finally, we made a suggestion of fracturing to the new well. We applied the comprehensive formation evaluation method to 12 new wells of the Permian low permeability formation. Compared with the real oil-testing results after fracturing, the judgment accordance rate is 75%. The researched method can be generalized to other low permeability formation.
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Low BTU Gas Monetization Technology Commercial Evaluation
More LessNatural gas is normally composed of three types of group components; i.e., hydrocarbons, inert and sour components. The natural gas hydrocarbon component consists of light straight chain hydrocarbons; i.e., methane, ethane, propane, butanes, pentane, etc. The inert component consists of nitrogen and water vapors whereas the sour component normally consists of carbon dioxide (CO2), hydrogen sulfide (H2S), mercaptans, carbonyl sulfide, etc. The inert and sour components need to be removed to control the high heating value (HHV) of sales gas to a minimum of 930 BTU/SCF to meet the desired fuel gas specification and to keep sour gas content to a permissible limit in terms of health and safety regulations. Gas purification and treatment technologies are required for removing the inert and sour gas components. Normally, a gas containing more than 20 mol% inert and sour gases is termed a sub quality natural gas (SQNG). This type of gas is normally a clean gas with less heavy hydrocarbon components and has a lower heating value. The inert and sour components need to be removed to meet the sales gas and fuel gas specifications. The Kingdom of Saudi Arabia has various undeveloped low BTU gas fields with significant gas reserves in the southern and northern part. Low BTU or “trash” gas monetization is required to meet the Kingdom’s growing future gas demand, minimize crude oil burning and spare crude oil for export. The Saudi Aramco Gas Operation department is responsible for future gas development as well as the operation and optimization of the existing gas plants. Due to the growth in energy demand in the kingdom, Saudi Aramco is considering and evaluating whether it should develop low BTU gases. In this regard, Saudi Aramco has undertaken several initiatives and carried out many technical and commercial studies to develop and monetize gas resources.
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Optimizing Offshore Gas Field Development with Large Wellbore Completion
Authors Ahmed Al-Baqawi, Amjad Ashri, Abdullah Al-Utaibi and Adnan Al-KananDuring 2008-2009, Saudi Aramco recorded two major nonassociated gas field discoveries in the Arabian Gulf. The initial plan was to develop both fields with deviated extended reach 7” completion wells, which will be drilled from multi-well platforms. Based on the challenging subsurface conditions of the problematic highly fractured shallow horizons, in addition to the thick, highly fractured, and excellent carbonate Khuff reservoir quality, the decision was carefully made to develop both fields with vertical large bore wells completed as monobore with 9⅝” pre-perforated uncemented liner across the pay zone and 9⅝” production tubing to the surface. The large bore wells are planned to be drilled from single-well platforms that can be strategically located around the two fields to allow efficient spacing and depletion to produce initial gas rates up to 300 MMscfd per well. The large bore well design has a potential for maximizing the gas production from each well and reducing the overall field development costs down by 45% by minimizing the number of wells and facilities required without jeopardizing the production, safety or integrity of the development projects. The shallow horizons in the newly discovered fields, along with the targeted Khuff reservoir, are considered to be highly faulted structures with many associated fractures that can continuously cause drilling problems with lost circulation and differential sticking. The newly planned vertical large bore wells tend to reduce drilling problems. Nevertheless, those planned vertical large bore wells are still capable of producing the required high gas rates. The intent of this paper is to highlight the multiple challenges faced during the early exploration and delineation phase of the fields and to share the experience of planning new offshore field development strategies for large bore wells with high reservoir temperature and pressure (T&P). Transforming from the original development plan to the optimized large wellbore completion plan, takes advantage of the excellent reservoir quality and high flow capacity, allowed for many optimization efforts. Such optimizations have changed the entire project strategy to accelerate the official onstream startup date without any compromises.
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Equation for Oil and Gas Two-Phase Flow into Vertical Well- A Theoretical Derivation
Authors Kegang Ling and Jun HeGenerally reservoirs are classified into five categories according to the reservoir fluids. Single phase flow in reservoir is expected during the production life for wet gas and dry gas reservoirs. But for black oil, volatile oil, and gas condensate reservoirs, two-phase flow will occur after pressure declines to saturated pressure and the second phase saturation reaches the critical saturation. Theoretical derivation of single-phase flow into vertical well had been done by former investigators. The solutions to different boundaries at different flow status were provided through different simplifications and assumptions. These solutions provide powerful tools for reservoir study. But when it comes to oil and gas two-phase flow, they cannot be applied. To the best of our knowledge there is no rigorous and theoretical derivation for the oil and gas two-phase flow into the well. In this study, rigorous and theoretical derivation of oil and gas two-phase flows from reservoir into the well was conducted. Starting from the famous Darcy’s equation, the flows of oil and gas are controlled by the rock/fluid properties, pressure, and temperature condition. The continuity equation was applied. With the combination of equations of state and the concept of compressibility, the governing equation of oil and gas two-phase flow was constructed. Even numerical approach is required to solve the equation to get gas and oil flow rates, the new equation still has its significance due to its theoretical and rigorous derivation. It can be used as a unique tool to solve the saturated oil and gas condensate reservoirs that experience two-phase flows. The proposed equation addresses the rigorous derivation of two-phase flow in a radial reservoir. It eliminates the uncertainty in the empirical equation and has the advantage of quickness and simplicity comparing with reservoir simulation method. It becomes a powerful tool for petroleum engineers.
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SPME Method Development for the Determination of Aliphatic Amines in Industrial Waste Water
More LessIn the presence of dissolved oxygen in the water inside a pipeline, the oxygen attacks the steel to form iron oxides. To prevent this, corrosion inhibitors are added to the crude oil streams. These chemicals are amines-based that form a film to coat the steel and prevent it from contacting the oxygen. Amines residuals should be monitored in the system and this is classically done by liquid-liquid extraction (LLE) of amines followed by colorimetric determination using spectrophotometry. In this work, solid phase microextraction (SPME), a novel extraction technique that uses no solvent, was used as a sample preparation technique to isolate the amines from the complex sample matrix and then the gas chromatography (GC) system was used for separation and quantification of amines. A flow-through system was used to simulate the process of flowing streams in pipelines during oil production. A method was developed to determine amines residuals at the lowest detection limit possible at the optimized conditions such as solution pH, ionic strength, and sand contents. It was found that residuals can be determined as low as 1 ng/mL using the GC system equipped with a flame ionization detector (FID). This method was developed in the lab using a model to simulate the flowing streams and containing synthesized waste water. This method is an environmental friendly technique that will minimize the use of hazardous solvents and therfore the need for the proper disposal of them. Also it does not require pretreatment steps of samples or many reagents to be used in the extraction process of amines residuals. Finally, it will provide more precise results in a timely manner for better and quicker actions.
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China's Future Energy Needs
Authors Albert Hornyak and Shapour VossoughiChina is the world's second-largest consumer of energy and the third-largest producer of energy. China consumes more than 10 percent of the world's energy, following only the United States. It is projected between 2015 and 2020 the world oil supply will flatten and then slowly decline. In contrast to declining oil reserves China's oil needs are projected to more than double by 2030. China's electricity and natural gas demand is expected to triple while reliance on coal is expected to double. If China maintains its current pace it will overtake the United States and become the largest consumer and producer of energy in the world. China's current plan to meet future energy needs is very much dependant on fossil fuels. According to industry reports coal (60%) and oil (27%) will account for 87 percent of China's total energy demand by 2030. If China does not utilize new cleaner burning initiatives into their coal-fired power generation plants China will continue to pollute the world and may cause irreversible damage. The World Heath Organizations reports that within the next two decades China will become the largest emitter of green house gases in the world. The effects of pollution on the Chinese economy are enormous. The World Bank estimates pollution costs China eight percent of GDP. Finally, if energy demand continues to grow at present rates, China may begin to crowd the United States and others out of the global energy market. The United States as the top consumer of energy will either have to curb consumption to make room for China, or will have to find a way to curb China's massive energy needs. Both China and the United States need to realize the powerful incentives which would be gained through mutual cooperation in the search for new energy reserves and energy sources.
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