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Second EAGE/SPE/AAPG Shale Gas Workshop in the Middle East
- Conference date: September 21-24, 2014
- Location: Dubai, United Arab Emirates
- Published: 21 September 2014
1 - 20 of 38 results
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Shale Gas Project Development
By C. HartmanSummaryShale gas reservoirs pose unique challenges when undertaking field development. To put it simply, shale gas reservoirs are source rocks. These organic rich mudstones contain extreme vertical and lateral heterogeneity, are dominated by nanometer sized pores, have complex storage mechanisms, and require costly hydraulic fracture stimulation to produce economic quantities of gas.
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Conditions to Export the Shale oil and Tight Gas Revolution out of North America
More LessSummaryAccording to the International Energy Agency, the world is entering a golden age of gas. Gas is at the same time an abundant but also a green resource when compared to oil and coal. This golden age will not only rely on conventional resources. Unconventional resources (shale gas, tight gas and coal bed methane) will play a major role in the future energy mix. According to the Energy Information Administration, shale gas could double the world gas resources.
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Differentiation of Natural vs. Drilling Induced Fractures in Shale Gas Wells Using Borehole Images– Critical for Determination of In-situ Stress
Authors T. Mahmood and K.A. MacPhersonSummaryNatural and drilling induced tensile fractures are routinely interpreted from borehole images; they provide a unique, high-resolution, borehole centric indication of the distribution and orientation of fractures for use in reservoir characterization, fracture modelling, geomechanics and comprehensive stress analysis. In shale gas wells in particular, the correct determination of in-situ stress direction is critical and misinterpretation can lead to serious errors, not only in the stress analysis, but in the overall characterization and development of the reservoir.
Unfortunately, drilling enhanced natural fractures and drilling induced tensile fractures can have similar appearances on the borehole images. This paper concentrates on demonstrating a number of criteria that can be used to differentiate natural from drilling induced fractures.
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Characteristics and Genetic Mechanism of Upper Triassic Xu-5 Member Shale Gas Reservoir in West Sichuan Depression
Authors H Meng and D.K. ZhongSummaryShale gas has become a new exploration target in China since 2009 and has been discovered in many basins which including Sichuan, Tarim, Ordos, Tuha, Songliao, Bohai Bay etc. and with a total reserves of over 26 × 1012m3. Xu-5 Member (the fifth member of Xujiahe Formation) in western Sichuan Basin is a kind of shale gas reservoir of lacustrine environments with a total reserve of 1.47∼1.68×1012m3.
In order to help with the gas exploration, this paper discusses the depositional and diagenetic controls on shale gas reservoir quality of the Xu-5 Member by using research methods of thin-section and FE-SEM observation, bulk-rock analysis as well as porosity & permeability measurements suitable for shale gas reservoir, and thus generates the conclusion that the quiet water environment is the most important controlling factor: Low-energy environments caused shale frequently interbedded with sandstone and siltstone, which was the controlling factor of shale constituents (high quartz contents) and thus made it easily to form fractures. Also, quiet water environment was oxygen free and rich in organic material, which was good for not only hydrocarbon generation but also developing micro-pores within organic matter.
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Petrophysical Analysis for Shale Gas Potential, Onshore Bahrain
Authors N.K. Alwast, R.A. Mireault and A.N. MukhtarSummaryAn initial petrophysical and geomechanical prognosis for potentially prospective shale intervals that warrant logging and testing in a new exploratory well is presented. The work was undertaken as part of the geological evaluation of the pre-Khuff clastic interval, onshore Bahrain. Drilling is planned for 2014. The evaluation was challenged by a data set that was limited to a depth structure map and one 1979 vintage well offset to the new drilling location. A second well in another fault block provided some additional log and cuttings information.
Log pay criteria for shale in the 1979 well were developed from conventional log analysis techniques; volume of shale, resistivity and neutron-porosity cutoffs. Initial estimates for the elastic properties of the shale (Young’s modulus, Poisson’s ratio) were developed from correlations and a synthetic shear log that was created for the 1979 well.
Despite the challenges presented by the quality and quantity of the data, the evaluation identified 461 feet of prospective shale intervals out of a gross interval of 5141 feet, with 7 sufficiently thick intervals to warrant logging and cuttings analysis for absorbed gas and kerogen content in the new well.
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Economic Success of Shale Gas Plays
More LessSummaryFacies analysis integrated with rock properties of the Lower Smackover Brown Dense formation reveals characteristics of an emerging shale gas play which deposited on distal and proximal carbonate ramp during Jurassic in the Interior Salt Basin. The formation divided into two distinctive layers consisted of dark brown calcareous shale and carbonates. Understanding of exploration procedures for shale gas plays based on rock properties is critical for economic success. Average rock properties within the interested interval gathered from several exploration drillings are necessary for calculation of the total amount of productive resources to reduce risks and uncertainties. Economic success of shale gas plays depends on finding general trends of play fair way, analysis of the rock properties, and operational efficiency of drilling and completion.
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Shale in Telisa Formation, Central Sumatera Basin as a Prospective Shale Gas Resource Based on Geochemical Data Analysis
Authors M.T. Gandapradana, K. Meninta and S.M. GomaaSummaryShale refers to fine grained, laminated, clastic sedimentary rocks that can be rich of organic matters. Shale gas is a natural gas which is trapped within the shale formation because of shale impermeable characteristic so we required fracture to provide permeability that can be made naturally or artificially. These days, world’s energy demand is increasing because of so many factors and at the same time conventional energy resource was decreasing for a last few years. In this situation, shale gas rise and rapidly growth to fulfill world’s energy demand.
Central Sumatera basin is bound to the southwest by Barisan Mountains geanticlinal uplift and volcanic arc, to the north by the Asahan arc, to the southeast by the Tigapuluh high, and to east by the Sunda craton. Telisa Formation is the focus study in this research located in Central Sumatera Basin. Telisa sediment was came from Sunda land in the Northeast side of the basin settings. This formation consists of mainly shale and laminated sandstone that deposited during Early to Mid Miocene. Telisa formation has a wide variety on vertical thickness range from 400–870 feet. Tectonically the basin was relatively stable during depositional of Telisa in a continuous basin sagging.
This research methods used literature study concerning in regional geology and especially in geochemical data analysis. According to us, Telisa formation has a great potential of shale gas resource. Therefore, it is interesting to discuss about Telisa formation potential of shale gas to alternate conventional energy to fulfill future energy demand.
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A Roadmap to Representative Data at the Nanoscale in Shale
More LessSummaryThe fine grained nature of shale makes scanning electron microscopy (SEM) an essential part of the core analysis suite of techniques. Both the imaging and the compositional analysis require a specific approach when working on shale samples.
In many shale reservoirs, the pores in the organic matter can be as small as 2nm. Imaging these small features comes at the cost of a very limited Field of View. The higher the magnification, the smaller the area that will be imaged. This raises serious questions about the representative nature of the SEM images. This paper describes a methodology where mosaics with increasing resolution and decreasing Field of View combined with EDS maps are analyzed digitally to uncover the representative features or building blocks that make up the rock fabric.
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Geochemical Studies of Black Shales for Shale Gas Prospects of the Semri Group, Vindhyan Basin, Exposed around Maihar Area
By U. BhanSummaryThe Proterozoic basins from different parts of the world viz. Lena Tunguska, Siberia; Amadeus and McArthur basins, Australia; Sichuan and Tarim basins, China and Huqf basin, Oman etc. have reported commercial production of oil and gas. The Vindhyan basin of India has all the favorable geological conditions which were conducive for generation and accumulation of Hydrocarbon within the basin. It is one of the several “Purana” (ancient) sedimentary basins of the Indian. It is a sickle-shaped basin, outcropping between the Archaean Aravalli-Bundelkhand province to the north and east and the Cretaceous Deccan Traps to the south and by the Great Boundary Fault to the west.
The TOC is varies from 0.1% to 4% in the study area. The black shales unit of the Rohtasgarh Limestone has higher TOC. The HI values are ranging, 0 to 51 mg HC/g TOC. A Tmax higher than 470° C represents the wet-gas zone to over maturation of organic matter. The HI vs. Tmax values show Type I and Type II (gas prone) kerogen field. Also, Oxygen Index (OI) vs. Hydrogen Index (HI) diagram indicates type II kerogen. The light gaseous hydrocarbon compositions are showing higher concentration of C1, C2 and C3 gases in the shales.
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Spectral Gamma Ray Signatures for Qusaiba Shale
Authors A. Sahin and M.O. AbouelreshSummaryThe gamma ray plots indicate that distinct gamma ray pattern exists for the Lower Silurian Qusaiba Shale reflecting its lithology and depositional environment. The statistical distributions of gamma ray parameters as well as well as the correlation patterns of Th/K and Th/U ratios provide significant evidence about the sources of sediments and environment of deposition.
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Challenges Associated with Shale Gas Development in Asia
Authors H. Parikh, A Patel and R. ChaudhariSummaryThe rapid development of shale gas throughout US shale gas plays such as the Barnett, Marcellus, Fayetteville and Haynesville has led to water management concerns.
There is a very limited potential for underground injection of fluids, as underground injection is considered to be consumptively lost from the hydrological cycle. Multiple withdrawals of water could decrease the ground water considerably. Waste water treatment by means of management of flow back water in sewage treatment plants also does not cater to the need of desalination and chlorination issues. In case of shale gas exploration where around 6 million gallons of fresh water is used per well, India might face severe water challenges. Shale’s have been explored as source rocks in 8 basins in India. In cases like Jaisalmer Basin, Rajasthan, it would nearly become impossible to meet such water demands. There is thus a need to recycle the water used and this paper would look into the matter that how flow back water could be managed giving niche solutions for India having extremely high temperature conditions compared to the US. Membrane based solutions which would significantly reduce the water footprint would be taken into consideration.
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Geological Characteristics of The Lower Silurian Qusaiba Shale, Rub Al-Khali Basin, Saudi Arabia
Authors A. Mustafa, A. Sahin, M.O. Abouelresh and M. HaririSummaryThe Lower Silurian Qusaiba Shale of Qalibah Formation is considered as the most prolific source rock for the Paleozoic petroleum system of Saudi Arabia. Additionally, it has significant potential for unconventional shale gas. This study has been conducted on about 30 feet continuous core of Lower Qusaiba hot shale, Rub Al-Khali basin, Saudi Arabia. Core description shows different lamination patterns (< 5mm: 5–15 mm and >15 mm), reveals that it is predominantly composed of fine lamination of fissile hot black shale and grey shale present alternatively. Grey shale is having high silica contents.
Sedimentary features including soft sedimentary deformation, bioturbation and natural fractures (both open and filled) have been observed at several locations in core samples. Thin section study reveals various grain types forming the framework of the rock samples and the pore space fillers (clay) between these grains. Grain types include detrital mineral grains (quartz, micas and heavy minerals). The rock types identified in samples are mainly argillaceous mudstones. It has very low inter-granular porosity of about 1 or <1 percent and mainly filled with cementing material clay. The fractures and micro-faults observed in core samples also attributed porosity to shale.
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Unlocking the Full potential of the Middle East Shale Assets
Authors A. M. Bouhlel, M. Mayerboeck and K. EderSummaryUnconventional resources such as shale plays are structurally simple yet geologically complex. Finding economically viable shale resources – sweet spots requires a detailed understanding of available geological, geophysical, and geochemical data.
To identify sweet spots early in the life of shale plays and select the right basin to develop shale resources, a petroleum systems approach is applied to generate meaningful evaluations. This integrated and systematic approach will enable all the underlying data to be audited and the entire assessment workflow to be reproducible and open for critical reviews. Furthermore, it enables a consistent approach in order to compare multiple shale plays and their economics.
Since reliable, comprehensive data concerning the behaviour of shale resource systems under varying conditions are not widely available in the Middle East, the petroleum system approach could yield key risk and valuable information, especially related to drilling investments; manage the uncertainties; maximize value of available and gathered data; and guide the operator to acquire the right data and the acreages for the right price at the right time.
The proposed approach utilizes all existing public data to understand the viability of shale gas and oil exploration in a basin.
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Kingdom Shale Gas Hydrocarbons as an Emerging Resource Play
Authors A. Ahmed, A. Hakami, H. Alsahfy and F. OyarzabalSummaryThe Kingdom of Saudi Arabia is rich with resources that include discovered and undiscovered hydrocarbons. An accelerated unconventional exploration program has been launched in Saudi Arabia to develop unconventional hydrocarbon resources in various basins. The unconventional, rich to dry gas plays that are being evaluated are located east of Ghawar (Jafurah Basin) and in the Rub Al-Khali basin. Initial results from wells drilled in the Jafurah Basin indicate the presence of a possible gas rich play within the Jurassic source rock section. The Jurassic sediments being targeted are some of the richest hydrocarbon source rocks in the world. These source rocks are calcareous and are interpreted to have been deposited in a restricted marine environment within an intra-shelf basin (Sharland et al, 2001). The Jafurah low was part of an intra-shelf basin that was formed by a rapid rise in relative sea-level drowning an isostatically sagged platform interior (Aigner et al, 1990).
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Seismic Acquisition, Processing and Interpretation for an Unconventional Basin in Saudi Arabia
Authors A. Alghamdi and H. AlsahfySummaryWith the increasing demand for more oil and gas, the exploration for unconventional reservoirs has been escalating in Saudi Arabia over the past few years. This new step in exploration is requiring new technologies, equipment, computers capabilities and expertise. Seismic acquisition and processing play a major role in the exploration of unconventional reservoirs. For this study, we will be discussing the impact of different acquisition design/efforts and processing flows of two surveys, acquired independently, on interpretation over a basin in Saudi Arabia. The first survey was a sparse 3D survey, acquired in 2002, initially intended for conventional exploration. The second survey was acquired in 2013 with wide azimuth and broadband acquisition design for the purpose of unconventional exploration.
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Tuwaiq Mountain Rock Physics Model
Authors M.S. Bin Gubair and A. BakhorjiSummaryThree different rock physics models for Tuwaiq Mountain (TQMN) carbonates were built to link the elastic properties of TQMN Formation carbonates to their organic matter content. First, to better understand the effect of the organic matter, an initial model of interpolation between 100 percent organic matter and a mineral point was built using the Hashin-Shtrikman model. The second model, a pore filling model, was built by combining the Hertz-Mindlin and Hashin-Shtrikman models, and the modified Gassmann equation. In this approach the porosity is created using the Hertz-Mindlin and the Hashin-Shtrikman models; the pores are filled with organic matter (as solid fill) using the modified Gassmann equation. These two models were able to predict the measured elastic properties of the formation. Due to the complexities of the pore shapes associated with carbonate rocks, a third differential effective medium (DEM) model was used to induce the porosity to the solid rock with different aspect ratios. The pores were then filled with organic matter using the modified Gassmann equation. The three models were tested for different elastic properties against values measured from sonic and density logs collected from two wells penetrating the formation. The agreements between the DEM model and the data were excellent.
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Shale Gas Sweet Spot Identification Seismic Method : A Case in Longmaxi, Sichuan Basin
Authors L. Liu, Z. Yusheng, Y. Gang, C. Fei and L. XueliSummaryFractures, TOC, brittleness are the key factors that influence the production of shale gas. We can extract the seismic coherence and curvature attributes from post-stack seismic data to analyze the fractures distribution characteristics of the target layer. For the pre-stack seismic data, we can predicate the development strength and direction of fractures based on the theory that separate-azimuth pre-stack seismic data velocity is various with different azimuth (VVA). In the region of the high brittleness, shale usually has high Young’s modulus, we can establish the relationship between the TOC, brittleness and combined elastic parameters of Young’s modulus, density (E * Rhob) with logging intersection, and extrapolated such relationship from predicating the TOC and brittleness distribution characteristics for a well to a three-dimensional block, achieving that the brittleness and TOC of shale gas reservoirs can be reflected with elastic parameter combinations result (E * Rhob), and finally it performed a comprehensive analysis for shale reservoir fractures, TOC, brittle distribution characteristics and selected the “sweet spot”, thus providing a basis for fracturing scheme design and optimization of subsequent horizontal wells.
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Core and Petrographic Sequential Analysis of Organic-Rich Shale
More LessSummaryIn this work, different samples from the unconventional gas-producing Barnett Shale, Fort worth Basin, Texas, USA have been subjected to a variety of sequential petrographic analysis techniques. The primary goal of this work is to develop best analysis procedures for such type of organic-rich shale, since size and color are of little help. The sample types include core and thin sections. The analysis has been conducted sequentially from core description, thin section imaging, examination with transmitted and reflected polarizing lights, electron microprobe to scanning electron microscope. Through the core description, color, contacts, ripples, reworking, bioturbation and fractures were noted. The ratios of clay to silt, biogenic and detrital quartz, abundance of calcite, diagenetic dolomite and pyrite minerals, fossil content, and micro sedimentary structures have been identified using petrographic analysis. Three types of micro to nano-porosity in the Barnett Shale (intergranular, fossil and organic matter) have been identified and imaged through sequential resolutions from polarizing, electron microprobe to scanning electron microscopes.
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Fracture Modes in the Silurian Qusaiba Shale Play, Northwest Saudi Arabia and their Geomechanical Implications
By M.S. AmeenSummaryFracture studies were conducted for unconventional prospect evaluation in the Silurian Qusaiba Shales, northwestern Saudi Arabia. Borehole image logs, oriented cores, seismic, and drilling observations were used in the studies. The fractures include natural fractures and induced fractures. The induced fractures (drilling-induced tensile fractures and breakouts) are a manifestation of borehole deformation due to in-situ stresses and were studied to assess the stress regime in terms of directions and magnitudes. The results show that the present day maximum horizontal in-situ stress trend varies from NNW-SSE to NNE-SSW, and show a regional pattern dominated by the Arabian plate tectonics.
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