- Home
- Conferences
- Conference Proceedings
- Conferences
IPTC 2014: International Petroleum Technology Conference
- Conference date: 19 Jan 2014 - 22 Jan 2014
- Location: Doha, Qatar
- Published: 19 January 2014
21 - 40 of 354 results
-
-
Waterflood Performance Monitoring of Fluvial Reservoir through Saturation Logging – A Case Study of Mangala field
Authors D. Prasad, S. Verma, P. Kumar, A.K. Singh, R. Tandon, V. Ravichandran, P. Shankar and P. SinghThis paper discusses the application of saturation logging to characterize the water flood performance, sweep, importance of vertical conformance in moderately varying to high net to gross fluvial system, at one of the largest onshore field Mangala in Barmer basin, India containing ~1.3 billion initial oil in-place. Mangala field was discovered in 2004 and was brought on production with hot water flooding in August 2009. Structurally Mangala is a tilted fault block consisting main oil bearing reservoirs of Fatehgarh group of Cretaceous/ Paleocene age as the main sandstone reservoir unit (~250 meters) dipping at around 9 degrees to the east. The Fatehgarh group is subdivided into 5 major reservoir layers litho-stratigraphically termed FM1 (top) to FM5 (base). The lower Fathegarh Formations (FM3 to FM5) are dominated by well-connected sheet flood and braided channel sands having net to gross ~ 80%, whilst the Upper Fathegarh Formation (FM1 and FM2) is dominated by more sinuous, laterally migrating fluvial channel sands transitioning into lacustrine depositional system at the top and having net to gross <50%. The reservoir in general is of high quality with multi-darcy permeability, porosity > 25%; with relatively viscous (15cp) and waxy crude. The FM1 and FM2 are developed with downdip edge line drive and inverted 9- spot pattern. The massive FM3 and FM4 sands have been developed with a downdip edge line drive and up-dip horizontal producers. Saturation logging with Production logging is very important tool in monitoring the field injection performance. Time lapsed saturation logging data suggested that the FM-3 is sweeping very nicely from the bottom whereas in FM-4, the intra-shale layers are extended and thus not allowing the bottom sweep in some area. The FM-1 has come up with the conformance issues which suggest that the injection is not getting uniformly distributed across layers, resulting in the non-uniform sweep. Saturation log has helped in monitoring varying sweep in different reservoir units, sand to sand correlation in highly heterogeneous FM1 reservoir unit with the integration of Production Logging and other data in Mangala field. The improved understanding of conformance, production and injection has helped in locating the un-swept areas targeted for selective injection and drilling infill wells.
-
-
-
Reservoir Simulation Modeling of the World's Largest Clastic Oil Field - The Greater Burgan Field, Kuwait
Authors E. Ma, S. Ryzhov, S. Gheorghiu, O. Hegazy, M. Banagale, M. Ibrahim, O. Gurpinar, L. Dashti, J.-M. Filak, R. Al-Houti, F. Ali and J. Al-HumoudThe Greater Burgan field in Kuwait is the largest clastic oil field in the world. Its sheer size, complex geology, intricate surface facility network, over 2,200 well completions and 65-years of production history associated with uncertainty present formidable challenges in reservoir simulation. In the last two decades, many flow simulation models, part-field and full-field, were developed as reservoir management tools to study depletion plan strategies and reservoir recovery options. The new 2011 Burgan reservoir simulation effort was not just another simulation project. Indeed, it was a major undertaking in terms of technical and human resource. The model size, innovative technology, supporting resources, integrated workflows and meticulous planning applied to this project were unprecedented in the history of the Greater Burgan field development. The quest began in 2009 with the construction of a Structural and Stratigraphic model, followed by Static modeling in 2010 and Dynamic modeling in 2011. Early dynamic model startup allowed integration between the static and dynamic modeling teams which resulted in a geological model suitable for reservoir simulation. This paper describes work done to prepare a representative numerical model which could be utilized to optimize the remaining life of the reservoir complex. Right from the onset, representative numerical modeling concerns were identified. These led to a systematic collaboration framework being built in place between the static and dynamic modeling teams. Calibration of the model to the historical observations was executed at three levels, Global, Regional and Wells – the Cascade Approach. The cascade approach was designed to enable a concerted model calibration effort in accordance with the recurrent data quality. For instance, while the total field production history attains a high degree of accuracy, the data at the regional Gathering Center (GC) is of a lower level of certainty, but far more reliable than the data at an individual well. Commercial modeling software have been utilized extensively to produce several utilities such as water encroachment maps, Repeat Formation Tester (RFT) matching tools and aquifer definition and adjustment workflows. Subsequently, synergy in the integrated use of these tools produced a robust model calibration process on all three levels in the cascade approach. The second part of the project was to develop a predictive simulation model to be used as a reservoir management tool to forecast and evaluate reservoir development options for ultimate recovery. Check-point prediction models were defined and constructed at regular intervals during the model calibration phase. This approach allowed qualitative assessment on the evolution towards a representative numerical model. Furthermore, it allowed synchronizing simulation workflows and expedited project deliverables. The overall result was a sound full-field reservoir simulation model that achieved a good match of production, pressure and saturation histories, leading to reliable forecasting of oil recovery under different development scenarios.
-
-
-
Lower Jurassic Source Rock Contribution on Cretaceous and Tertiary Reservoirs Hydrocarbon Filling of Oil Fields, North West Persian Gulf, Iran
Authors P. Hassanzadeh and M. KhaleghiIn the first comprehensive study of the Northwest margin of Persian Gulf basin petroleum system of offshore Southwest Iran, we test oil–source rock correlation through molecular biomarker and Carbon Isotope analysis of oil samples from wells scattered throughout the region, as well as purported source rocks. The chemical compositions of 11 crude oils and 9 extracts of potential source rocks from the Bahregansar-Hendijan High and two adjacent fields of the North West Persian Gulf sedimentary Basin, Iran were studied in detail by geochemical methods in order to understand their genetic relationship. The oil samples were collected from the all producing fields. The rock samples studies, selected after Rock-Eval pyrolysis screening of a large suite of samples, consist of 32 shale samples distributing from Lower Cretaceous up to Lower Tertiary in the stratigraphic column of the studied oilfield. The new data presented in this manuscript suggest that the oils constitute two oil families, and that the source rock was predominant marine shale deposited in an oxic to suboxic environment. Possible source rocks were selected and analyzed from different wells and compared with the oils. A negative correlation suggests that Upper Cretaceous intervals of limestone, marl, and black shale previously believed to be important source rocks can be discounted as an important contributor to Northwest Persian Gulf basin oils. Instead, the new data suggest a Lower Jurassic source rock contribution in charging Cretaceous and Tertiary reservoirs of Soroush, Abouzar, Nowroz and Arash oil fields.
-
-
-
Qualification of an Innovative Sealant to Ensure Hydraulic Isolation in TTRD Application in the Presence of a Downhole Pressure and Temperature Gauge Cable
By J. BedelIn a mature field, where the strategy for accessing the remaining reserves is driven predominantly by cost reduction, through-tubing rotary drilling (TTRD) can provide the optimal solution. TTRD allows for low-cost sidetracking opportunities to near-wellbore targets by leaving the existing completion and Christmas tree in place. Additional time and cost savings are achieved once the well has been drilled as there is no need to run a new completion. In a project in the North Sea, the casing design requires that the TTRD candidate wells have a dual-casing exit above the production packer to access the location of the proposed hydrocarbon target. This operation requires a cement plug to be circulated into the annulus between the 5.5 × 7-in. tubing and the 9 ⅝-in. casing. The purpose of this specific cement plug is to provide tubing stability during the window milling operation and annulus integrity for the lifecycle of the new TTRD well. It will then act as a production packer, and it will also serve as the first abandonment plug for the donor well. Finally, the top of cement of the annulus cement plug should also leave enough space below the 9 ⅝-in. casing to allow for the final abandonment. The main complication with this cementing operation is caused by a downhole pressure and temperature gauge cable that runs from below the proposed kickoff point up to the tubing hanger. The risk is that this cable could potentially cause micro-annuli within the annulus cement plug and hence impair the integrity of the well. A further potential issue can arise if the gauge cable is sheared during the window milling operation, thus creating the potential for hydrocarbons to travel up through its core to the tubing hanger. A cementing service company designed and qualified an innovative sealant that can be used to meet the above criteria. Large-scale laboratory testing was undertaken to meet the technical and operational acceptance criteria.
-
-
-
New Insights into Low Salinity Water Injection Effect on Oil Recovery from Carbonate Reservoirs
Authors E.W. Al-Shalabi, K. Sepehrnoori and M. DelshadLow salinity water injection (LSWI) is gaining popularity as an improved oil recovery technique on account of being cost effective compared to other water based enhanced oil recovery methods such as chemical and steam flooding. In this paper, the wettability alteration option in our in-house simulator is used to history match and provide some insights in different seawater dilution cycles based on recently published corefloods. Two newly proposed methodologies to model dilution cycles are employed. We successfully modeled the experiments enhancing the wettability alteration model in the simulator using two different scaling factors. The study also revealed that the process is more sensitive to oil relative permeability compared to that of the water phase. A linear interpolation model for residual oil saturation (Sor) was proposed.
-
-
-
How to Find Low Resistivity Pay in a Mature Oil Field K- Field Case Study
Authors S.M. Poerboyo and K.R. SuharyaPrior to 2010, all oil from the K field was produced from the Lower Sihapas Formation, where oil could easily be identified from electrical logs in these thick, high-quality sands. Then, in 2010, something unusual happened. When drilling an infill well, we noticed good oil indications from mud logs in sands above the Lower Sihapas Formation, despite the low resistivity less than 4 ohm-m. We completed the sand and it flowed 146 BOPD with zero water. This unexpected result prompted us to conduct a short two-week study to identify other candidate wells. The study consisted of: collection of mud and wireline log data in all K wells; re-running petrophysical analysis using new a, m and n values for low resistivity sands; and ranking candidate wells based on sand quality, gas readings, oil shows, initial oil rate prediction, well cost and the chance of making money. The study identified 17 candidate wells to re-complete in the Upper Sihapas. To date, we have worked over seven wells with an oil gain of 700 BOPD and estimated incremental oil recovery of 175 million stock tank barrels. One of the worked-over wells, the one with the lowest EMV, flowed water. This paper describes the study, the resultant workover campaign and lessons learned.
-
-
-
Calibrating Log Derived Stress Profiles in Anisotropic Shale Gas Formations- Incorporating Lab and Field's Measurements for Localized Model
Authors A. Almarzooq, H. Aljeshi and A. AlAkeelyThe complex properties of the unconventional gas resources pose challenges to petrophysical evaluation techniques and tools. Data from standard logging tools and standard interpretation techniques produce high levels of uncertainties in the analysis, hence, limiting their reliability in producing thorough petrophysical solutions. Both tight and shale gas formations add multiple layers of complexity to the petrophysical evaluation with complex lithology and heterogeneity causing uncertainty in the hydrocarbon volume calculations and hydraulic fracturing completion designs. Without an accurate completions design, it would not be possible to produce at an economic rate or volume from these formations. Therefore, the need for accurate petrophysical and Geomechanical properties is critical for shale gas formations development. This paper provides field examples with workflow for identifying the anisotropy, calculating the log derived stress profiles and demonstrating the use of lab and field data for calibrating the log measurement. The lab measurements include the elastic moduli conversion dynamic (from logs) to static (from laboratory), stiffness tensors utilizing the oriented velocities in addition to rock strength and related parameters. This part includes the use of oriented velocities from the lab to validate and correct the existing tensors' correlations (Annie). Correcting the logging tool's measurement for factors such as the gas content and the acoustic conversion models will also be illustrated. The field data include the integration of the pre-fracturing job or mini fracturing to calibrate the calculated minimum horizontal stress (closure pressure) and post fracture analysis to validate the models. The result of these calibrations is a more accurate estimation of the formation stress profiles which improves the completion designs. Once these calibrations are done correctly, more accurate stress profile can be calculated in offset areas where cores or mini-fracturing measurements are unavailable. This paper shows the process for calibrating the log derived stress profile and goes through the components and uncertainty.
-
-
-
The Controlled Freeze Zone Technology for the Commercialization of Sour Gas Resources
Authors J.A. Valencia, S.D. Kelman, A.K. Nagavarapu and D.W. MaherControlled Freeze Zone™ is an efficient single-step cryogenic distillation process for the removal of carbon dioxide, hydrogen sulfide and other impurities from natural gas. Rather than avoiding the freezing of CO2 at cryogenic temperatures, the solidification is allowed to take place, albeit in a very controlled fashion. The technology has shown the potential to more efficiently and cost-effectively separate carbon dioxide and other impurities from natural gas, and to discharge these contaminants as a high-pressure liquid stream ready for underground injection, either for enhanced oil recovery applications or for acid gas injection disposal.
-
-
-
The Hydrocarbon Pipeline Network and Development in Qatar
More LessThe Transmission and Distribution Network comprises of interconnected gas and oil pipelines network of approximately 3000 km length, associated manifolds and more than 70 distribution stations located through Qatar. The hydrocarbons transported in this network such as sweet Methane gas, Ethane network, stripped associated gases, and tail gas, etc… are all utilized as fuel and feedstock gases to supply the various power plants and industries located in the State of Qatar. In addition, Transmission and distribution network is also responsible to monitor and maintain all QP and third party Companies’ pipelines such as row gas, condensate and LPG pipelines, Ethylene pipeline and crude oil pipelines. As the State of Qatar is booming with tremendous expansion and development to the infrastructure for hosting the FIFA World cup 2022 and to meet its 2030 National Vision, the Gas pipeline network is also being expanded to meet Year 2030 supply and demand forecast, future industries and Urban and infrastructure development. The aim of this paper is to illustrate the development/expansion of QP pipelines network to cover the future national gas supply and demand forecast up to 2030. This will cover the expansion of power generation due to the increase in future national energy demand and the expansion and requirement for the new industries. In addition, the paper will highlight the urban development requirement such as domestic gas supply to houses and using Compressed Natural Gas CNG for local transportation. Moreover, the paper will discuss the infrastructure developments such as the new pipeline corridor tidiness and rationalization, new rail way interfaces with the existing pipeline network, and new Jet fuel requirement to the new Doha International Airport. All the significant challenges and lessons learnt for the network’s planning, interfaces, construction, re-routing and operational challenges will be also addressed in this paper.
-
-
-
IPM Tool for Strategic Decisions: Diverse Applications of IPM in the Supergiant Tengiz Field
Authors S. Kabdenov, M. Aitkazin, S. Macary and A. AitzhanovIntegrated Production Modeling (IPM) is probably the most popular suite of software for production optimization and planning. It affords the opportunity to model the entire production system from the reservoir through the surface gathering system to the process facilities. This paper describes applications of IPM to the various strategic decisions made in Tengizchevroil LLP (TCO). Within TCO, a full field IPM model is used for an integrated production capacity management plan considering three time periods: short, mid and long-term. Each model has its own strategic focus and is owned by a specific team, all working together in close communication. The short-term model is used to investigate the impact of field operations and surveillance on field production capacity so that all processing facilities are kept full. The mid-term model is used for debottlenecking and gathering system optimization, understanding new drilling hook-ups, and impact of workovers on system capacity. This model uses a time window of up to five years and is also used for Business Plan support. The long-term model, which is the core of this paper, focuses on major capital projects and is typically run for decades. The main objective of long-term IPM modeling is to run production forecasts while honoring surface constraints; keeping the existing and future processing facilities full is the desired outcome. The long-term model handles not only the oil system, but also sour gas injection and waste water disposal. It models all current gathering systems, with whatever modifications or short-term projects adopted by the mid-term model inclusive and future growth plans. Examples, lessons learned, and challenges of strategic decisions made by using IPM will be shown and discussed in this paper. This includes well count study, pipeline sizing, meter station assignment, timing of rigs and projects, and drilling schedule. One of the main lessons learned was the importance of cooperation with the reservoir simulation team in unifying constraints, incorporating the impact of reservoir uncertainty on production profiles, and developing mitigation strategies for unfavorable outcomes. Other value is derived from coordinating base business IPM results with those of the design team that handles future growth projects.
-
-
-
Advanced Reservoir Characterization for CO2 Storage
Authors A. Al-Menhali, C. Reynolds, P. Lai, B. Niu, N. Nicholls, J. Crawshaw and S. KrevorInjection of CO2 into the subsurface is of interest for CO2 storage and enhanced oil recovery (EOR). There are, however, major unresolved questions around the multiphase flow physics and reactive processes that will take place after CO2 is injected, particularly in carbonate rock reservoirs. For example, the wetting properties of CO2-brine-rock systems will impact the efficiency of EOR operations and CO2 storage but reported contact angles range widely from strongly water-wet to intermediate wet. Similar uncertainties exist for properties including the relative permeability and the impact of chemical reaction on flow. In this presentation we present initial results from laboratory studies investigating the physics of multiphase flow and reactive transport for CO2-brine systems. We use traditional and novel core flooding techniques and x-ray imaging to resolve uncertainties around the CO2-brine contact angle, relative permeability, residual trapping, and feedbacks between chemical reaction and flow in carbonate rocks.
-
-
-
Successful Application of Compact Low Pressure System in CC Field, an Optimized Version for Smaller Surface Deck Platforms
Authors Z.M. Mainuri, M.H. Mohamad, D. Gajet and P.K. HoongOptimization of mature fields in maximizing the hydrocarbon recovery has been a major concern for exploration and production companies including PETRONAS Carigali Sdn. Bhd (PCSB). CC is a brown field, situated in south central region of the DD Province of the Sarawak Basin.Since CC field has marginal reserves, an effort to enhance the production was initiated with the objective of economically boosting the remaining reserves.The proven Low Pressure System (LPS) that is widely implemented across Petronas operating fields has benefited CC in optimizing the production by lowering the existing surface back pressure. However, the challenges faced in implementing the system in CC are platform surface constraintand unmanned-operation-at-night philosophy. Through further optimization on the existing LPS design and the estimated production from LPS well candidates, Compact Low Pressure System (CLPS) was born. The smaller package is lighter compared to existing system and has more flexibility and mobility. The separator process can cater up to 4000 bopd with approximately 4.0 MMscf/d of gas disengagement. This package consists of three major equipments compacted in one skid, which are shut down valve (SDV) for emergency purposes, vertical separator (V-100) for liquid storage and flow rate measurement, and transfer pump for pumping back the liquid to the main production line. The total dry weight of this skid is approximately 9.8 tonnes with smaller foot print of 8.3 m2. Preliminary well candidates were chosen mainly based on well status (idle well/string were given higher priority), water cut and sand control equipment in place. Then, a network model was generated using Integrated Production Modeling (IPM) software to simulate several operating scenarios and choose the best candidates. To-date, the additional oil gained from the selected 5 wells is approximately 400-600 bopd. With this achievement, CLPS has shown the capability of improving the production by overcoming the surface back pressure impact and solving space constraint issues for wells located in small wellhead platforms.
-
-
-
RasGas Experience with Production Optimisation System, a Success Story
Authors Sabry A. Mohammed, Mokhtar Berzou, L.B. Morshidi and Hani Al-Kharazl-time database for real-time monitoring and system updates. The PROMPT system is model centric and relies on rigorous physics, while its strength relies on using multiple seamless automatic and manual workflows. Many key calculations take place automatically and continuously however, other central workflows rely on engineering judgment such as well models updates. The PROMPT system has successfully demonstrated its reliability in supporting RasGas efforts to achieve long term production deliverability and secure RasGas’ contractual Liquefied Natural Gas (LNG) demand by meeting the LNG production targets and maximising recovery. This is attained by producing the field/wells per the optimum depletion strategy while honoring facility constraints, system availability (well/platforms/pipeline, planned and unplanned downtime, etc.) and operational limits. RasGas uses the PROMPT system to generate well production guidelines as per the optimum reservoir depletion strategy to meet short term production targets. The PROMPT platform is equipped with an optimizer “Excel Solver” where the desired depletion strategy is coded and implemented. This depletion strategy is translated to actuality by generating short-term production guidelines on a regular basis while honoring the production system constraints. PROMPT is effectively used for real time monitoring and compliance with production guidelines, such as monitoring deviations of daily production from pre-defined targets, and for making well rate adjustments during planned/unplanned shutdowns or increased demand. It gives the engineers the ability to test different well operating strategies in off-line simulation to fine-tune production guidelines to meet changing field conditions and enables effective data integration between RasGas engineers in the Sub-surface group with those in the Operations groups.
-
-
-
Carbonate Reservoir Analogues and Clumped Isotopes: How Combined Geometries and Geochemistry of Outcrops Help Reservoir Management in the Middle East
Authors C. M. John, V. Vandeginste, A.-L. Jourdan, T. M. Kluge, S. Davis, C. Sena, M. Hönig and J. BeckertPetroleum geologists working in carbonate plays are facing two common and inter-connected challenges linked to optimizing production. First, constraining the geometry, spatial distribution and inter-connectivity of reservoir geobodies is crucial as these properties can control the permeability anisotropy of reservoirs zones. This is difficult to do at the inter-well scale due to the limited resolution of seismic methods (20 meters or higher) compared to the size of typical reservoir geobodies (tens of centimers to meters and higher) and the very heterogeneous nature of carbonate reservoirs. Furthermore, diagenetic transformations are very important in carbonate reservoirs. Being able to fingerprint the process and timing of diagenetic transformation is crucial to a correct assessement of the distribution of cemented zones in the subsurface. The issue of diagenesis is also important for organic matter maturation and the timing of oil migration, and therefore the second challenge faced by reservoir geologists in carbonate plays is one of constraining as well as possible the thermal history of the targeted basin. This paper reports on the results of a major long-term research effort that addresses some aspects of this double challenge in the Middle East, and that focused on novel isotopic methods to constrain the thermal history of carbonate phases in the context of the geometry of geobodies measured at the outcrop. Geological work under the Qatar Carbonates and Carbon Storage Centre (QCCSRC), funded jointly by Qatar Petroleum, Shell and the Qatar Science & Technology Park, has as its long-term research goals to improve characterization of subsurface anisotropies in carbonate reservoirs, notably for CCS operations.
-
-
-
High GOR ESP Experience and Development Concept for a Challenging Oil Field in the Sultanate of Oman
Authors M. De Berredo, I. Sipra, H. Al Muqbali, A. Al-Bimani and G.H. Lanierg’s to date, the study provided the technical basis to assure feasibility of the proposed development plan for the expected high GOR producing environment. Further economic assessment of the artificial-lift selection decision, which is not detailed in this paper, supported a significant impact to the project on the order of 1/3 of its expected value. This paper summarizes the range of PDO operating experience to date with ESPs installed in high GOR conditions. Additional details are shared regarding the feasibility study for field T including supporting rational for the artificial-lift selection for the project concept selection, proposed well completion concept design and the artificial-lift economic evaluation. Finally, established best practices for high GOR fields and key challenges going forward will be discussed.
-
-
-
Modeling and Analysis of Axial and Torsional Vibrations of Drillstrings with Drag Bits
Authors J.M. Kamel and A. YigitRotary oil-well drilling systems supplied with drag bits are used to drill deep boreholes for the exploration and the production of oil and natural gas. Drilling systems usually suffer from severe vibrations, which occur as axial, lateral and torsional oscillations. These vibrations mostly cause failures of drill-strings, abrasive wear of tubulars, damage of the bit, reduction of the rate of penetration (ROP), and incur high costs. Despite extensive research in this area, there is still a need to develop a consistent model that adequately captures all relevant phenomena such as nonlinear cutting and friction forces at the bit/formation interface, drive system characteristics and coupling between various models of vibrations. This study presents a physically consistent nonlinear lumped-parameter model for the coupled axial and torsional motions of a rotating drill string equipped with a drag bit. An innovative cutting and contact model is used to model rock/bit interaction. The dynamics of rotary and axial drive systems including hoisting system are also considered. The equations of motion are solved numerically to carry out parametric studies. The effects of various operational parameters are investigated for achieving a smooth and efficient drilling. The proposed model appears to capture stick-slip and bit-bounce as the simulation results qualitatively agree well with field observations and published theoretical results. The rotational and axial motions of the bit are obtained as a result of the overall dynamic behavior rather than prescribed functions or constants. The results show that with a proper choice of operational parameters it is possible to minimize the effects of stick-slip and bit-bounce and to increase the ROP. Therefore, it is anticipated that the results will help reduce the time spent in drilling process and costs incurred due to severe vibrations and consequent damage to equipment.
-
-
-
Coupled Subsurface and Surface model: A Case Study
Authors B.A. Shammari, S.A. Putra, H.A. Nooruddin, I.J. Bellaci and A.T. ShammariAn integrated model that couples surface and subsurface models was developed for a huge carbonate oil reservoir overlain by a large gas-cap located in the Middle East region. The main objective of the integrated model is to quickly evaluate changes in production strategy and provide more accurate forecast of field performance than with conventional approaches where surface and subsurface performance are evaluated separately. Building a fully integrated model is a very challenging task, due to the complex nature of the field process, including compositional variations, NGL processing and evaluation of gas disposition options. The surface network model was developed to allow evaluation of liquid and gas velocity in the flowlines and trunklines, and erosional velocity and back pressure to every well in the network. Trunklines were modeled with detailed elevation profiles to capture the complex nature of desert terrain found in the field. The subsurface model is a huge resolution model with more than 60 million grid-cells. The reservoir simulation model is compositional, having nine-components and runs on a state-of-the-art in-house simulator, GigaPOWERSTM. This paper highlights the process in building the fully coupled model by a multidisciplinary team, including the subsurface model, wellbore models, surface network model, and the integration layer between those different standalone models. The paper also discusses the issues encountered during building the integrated model and how those challenges were resolved.
-
-
-
Uncertainty of Porosity Measurement Correlations using NMR and Conventional Logging in Carbonate Reservoirs
Authors H.S. Al-Kharaa, M.A. Al-Amri, M. Naser and T.M. OkashaPorosity is a dimensionless parameter, defined as the ratio of pore volume filled with fluid to the bulk volume. Porosity is a critical volumetric parameter used to estimate the reserve for a given reservoir and it can be used as an input for reservoir simulation as well. In addition, porosity can be classified into two types, effective porosity (interconnected pores) and total porosity (connected and isolated pores). Total porosity is defined as the sum of effective porosity and clay bound water (CBW). In other words, total porosity obtained from conventional logging tools will be equal to effective porosity in the absence of clay and while it is not the case when clay is present. There are several methods used to estimate porosity of the formation. These include: measuring actual porosity in the core laboratory, computerized tomography (CT) scan, neutron-density logging, sonic tools, and NMR logging tools. All conventional logging tools (neutron-density and sonic logging tools) are strongly dependent on lithology, whereas NMR logging tool is independent of lithology. The NMR logging the most accurate compared to all other methods since it is independent of the reservoir lithology. It can be used to estimate the reservoir porosity directly without the knowledge of matrix lithology. On the other hand, conventional logging such as neutron-density and acoustic depend strongly on lithology which might yield incorrect porosity measurement. Several studies have been conducted to estimate porosity for both sandstone and carbonate reservoirs using different logging tools, however, determining porosity is a challenge in 2 IPTC 17260 complex and unconventional lithologies. In sandstone, the presence of shale and clay minerals will affect the response of all porosity tools. Carbonate is even more complicated than sandstone due to its heterogeneity and triple porosity system (pores, vugs, and fractures). In addition, the assessment of porosity measurements accuracy using NMR logging will be considered in this study. An attempt will be made to develop an empirical correlation from NMR data to obtain reliable porosity estimation. In this work, more than hundred NMR reading tool were used to develop empirical correlations to estimate the free fluid (FFI) and Clay bound Water (CBW) for Arab D reservoir. This can be used as a checking parameter for the used cutoff values by the service company to ensure full compliance with the measured values in the laboratory. The correlations also will optimize the logging tool time and reduce the operation cost. Results of pre-study (SPE-168110) showed that a clear criterion to divide the formations into dolomitic and clean formation (pure limestone) should be established to get more accurate result. In the dolomitic formation, correlations for CBW showed R of 0.96 and for FFI R is 0.99.In addition, in clean formation, correlations showed for CBW is R of 0.98 and for FFI R is 0.99.
-
-
-
Thinly Bedded Reservoir Characterization, from Qualitative to Quantitative Approach, Case Studies in a Cenozoic Basin of Malaysia
Authors B.P. Kantaatmadja, G.S. Thu, R. Masoudi, M.B. Othman and M.N.B.A. RahmanThe limit of resolution of seismic data is a complex issue that involves not only wavelet frequency, phase characters, data quality (S/N), interference, tuning, but also criteria on how to measure resolvability, which can hamper confident lithology, porosity and fluid prediction of thinly bedded reservoirs. Widess‟s classic paper (1973) concluded that for thin beds (below λ/8 wavelength), the seismic character, peak/trough time and frequency do not change appreciably with thickness, and also amplitude varies almost linearly with thickness, which goes to zero at zero thickness. Thus, λ/8 of wavelength is considered to be the fundamental limit of vertical seismic resolution which depends on velocity and mainly frequency. Tirado‟s work (2004) revised Widess‟s model, which is not applicable to the real reflection, and concluded that as the bed thickness decreases, there is a gradual increase in the peak frequency, but below a certain thickness (at some fraction of tuning thickness), the peak frequency rolls off and return to the peak frequency of the wavelet at zero thickness. Thus, the key factor in determining seismic resolution is by enhancing the frequency spectral bandwidth which, nowadays, can be effectively achieved either by acquiring Broadband Acquisition or conducting Broadband Seismic Re-Processing. We demonstrated various case studies on thinly bedded reservoirs using qualitative and qualitative techniques in a Cenozoic basin in Malaysia. The qualitative techniques involve the -90° Phase wavelets with Relative Colored Inversion, Spectral Decomposition, and ThinMAN broadband spectral inversion. The quantitative approach includes an integrated multi-disciplinary technique combining with Cascading AVO Simultaneous inversion and Stochastic Inversion calibrated with conventional and SHARP-OBMI logs, which together, significantly enhance imaging of the thinly bedded reservoirs. This unique integrated workflow has been applied in the field study, resulting in an increase of about 30% of hydrocarbon in-place volume, and has been successfully validated with available production/well data as well as newly drilled wells.
-
-
-
Reservoir Characterization And 3D Static Model In Tight Carbonate, Open Up Reserves, Tuba Reservoir Sabiriyah Field, North Kuwait
Authors S. Abd El-Aziz, W. Bryant, C. Vemparala and S. Al-RasheediThe Sabiriyah Tuba Reservoir has significant hydrocarbon resources in place with a high degree of reservoir rock and fluid heterogeneity. Until recently, it received marginal development attention, and was considered one of the ‘Minor Reservoirs’ of North Kuwait with limited opportunity for production enhancement. Improved reservoir Characterization and the development of a 3D Static model, together with Horizontal Completion technology have now opened up new opportunities for an accelerated development strategy. The Tuba formation represents a carbonate ramp with different lithofacies association from more proximal depositional setting to more distal environments. Even though the northern area of the field is represented by deeper facies, the reservoir quality shows comparable porosity and permeability trends. The porous and permeable aggradational and progradational carbonate of Upper & Lower Tuba respectively, constitute the main oil accumulations where reservoir quality is strongly controlled by structure, primary depositional fabrics, as well as extensive dissolution process. It has a significant vertical and horizontal variation in oil quality ranging from low 11-18 API oils to better quality 23 API oils. Current performance of the producer wells indicates that Tuba has the potential to enhance dry oil production. Tuba reservoir is divided into 3 main stratigraphic units, Upper, Middle & Lower and each unit is further subdivided into sub-layers. The geological layering based on sequence stratigraphy combined with 3D seismic data provided the framework for structural model. The high resolution model was achieved by generating 3D faulted grids and integrating all the components such as all the deterministic structure maps and petrophysical results in to one geocellular model applying different approaches and techniques. The model and visualization proved valuable in the interpretation of the primary depositional and secondary digenetic processes that left their imprints on Tuba rocks The study helped accelerate the development of the Tuba reservoir, and led to new Drilling & Workover opportunities that converted to >500% increase in Oil production. Additionally, from this study, an estimated increase in recoverable reserves of >60% would now support a long term development plan and reserves growth for North Kuwait.
-