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Abstract With the depletion of conventional fossil resources and growing demand for energy, unconventional energy is playing a more important role in the world energy market. Nowadays, unconventional gas production contributes to around 50% of total gas output in the USA Shale gas has significantly changed the energy portfolio in the USA and reduced America's dependence on oil and gas imports. The case histories of four major shale gas plays in the USA, Antrim, Barnett, Haynesville, and Marcellus, are discussed in this paper. It is concluded that the phenomenal shale gas success in the USA benefitted from improved horizontal drilling and fracturing technology, positive government policy and tax incentives, and mature surface pipeline system. China is facing with soaring energy demand and the pressure to cut greenhouse gas emission. These factors have motivated oil operators to explore and exploit the enormous shale gas resources in China, especially in the Sichuan and Tarim Basins. But several factors may hinder the future of shale gas in China. Firstly, Chinese operators have to develop suitable drilling and fracturing technologies. Secondly, lack of water resources may restrain fracturing operations. Thirdly, China lacks mature pipeline system. Fourthly, the Chinese national oil companies may not be interested in producing shale gas due to its low price and low profits. Therefore, it is emergent for the Chinese government to invest in innovations and infrastructure, and allow independent and private companies to engage in the shale gas business.
- North America > United States > Texas (0.72)
- North America > United States > Pennsylvania (0.72)
- North America > United States > New York (0.50)
- (3 more...)
- Government > Regional Government > Asia Government > China Government (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.95)
- North America > United States > West Virginia > Appalachian Basin > Utica Shale Formation (0.99)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- (32 more...)
Abstract A detailed study of the thermophysical properties of Devonian shales from the central and eastern United States has been carried out. The properties encompass a wide spectrum of material properties such as thermal conductivity, thermal diffusivity, specific heat, dielectric constant and sonic velocities. The importance of such measurements in on-field applications in oil shale technology is highlighted. Comparison of the trends in the various properties observed for Devonian shales as a function of temperature with data obtained previously for Green River oil shales is presented. previously for Green River oil shales is presented. Similarities and differences in the thermophysical behavior of the two types of shales are discussed. Introduction Gas-bearing oil shales of Devonian age occur extensively in the central and eastern United States. These shale deposits represent an important potential source of natural gas. Estimates of oil and gas potential of Devonian shales are somewhat variable potential of Devonian shales are somewhat variable although they are in the neighborhood of several hundred trillion cubic feet of gas. Thermophysical characterization of Devonian shales is relevant to the development and optimization of methods that are currently envisaged for the recovery of natural gas from these deposits. Most of these methods rely on the application of heat to pyrolyze the organic constituents of the shale. An understanding of the effect of temperature on the properties of these shales is thus crucial for efficient process design. The term "thermophysical" is used in the present context to represent those parameters which are directly or indirectly related to parameters which are directly or indirectly related to the transport, absorption or release of heat. Properties such as thermal conductivity, thermal diffusivity Properties such as thermal conductivity, thermal diffusivity and specific heat fall naturally into this definitive classification scheme. For materials like oil shales which are thermally active, i.e., those which undergo thermal decomposition or phase transformation, it is also useful to characterize their thermal behavior by techniques such as Differential Scanning Calorimetry (DSC). Electrical and mechanical properties have customarily become an integral part of thermophysical characterization in view of their extreme sensitivity to changes taking place in the material on application of heat. The present article focuses on the above aspects of the thermophysical behavior of Devonian shales. A wide spectrum of measurement parameters has been employed to yield a self-consistent picture on the overall thermophysical behavior of these oil shales. The properties that were measured, the techniques employed and the relevance of these experimental results in some typical on-field applications are listed in Table 1. The work reported in this paper represents the first instance of a complete thermophysical characterization of Devonian shales. In previous papers from this laboratory, the electrical, thermal and mechanical behavior of Green River oil shales was reported. In this article, comparisons of the various aspects in the thermophysical behavior of those shales with the corresponding trends for Devonian shales will be highlighted. EXPERIMENTAL a) Samples: Measurements were performed on cored oil shale samples of appropriate dimensions that were drilled from crack-free massive blocks. Michigan shales were obtained from wells drilled in Sanilac County with core depths ranging between 1303 - 1306 ft. Kentucky oil shale samples were obtained from the Sweetland Creek member (core depth: 2016โ2040 ft, average thickness 24 ft) of the New Albany deposits. The Green River oil shale samples were selected from cores drilled in the Anvil Points and Logan Wash deposits. The coring direction was nominally perpendicular to the stratigraphic planes of the shale. perpendicular to the stratigraphic planes of the shale. Oil yields of the various shale samples were obtained from pulsed NMR assay. All samples were carefully dried in pulsed NMR assay. All samples were carefully dried in vacuum at room temperature prior to measurement. Repeatability of the experimental results and any possible variations arising from compositional possible variations arising from compositional inhomogeneity of the shale, were systematically checked by duplicate runs on samples cored at approximately 19 mm intervals from the blocks (vide infra). b) Techniques: An outline of the various techniques employed for the thermophysical characterization (cf Table 1) is given below. Details of the measurement systems, calibration etc. are reported elsewhere.
- North America > United States > Wyoming > Green River Basin (0.99)
- North America > United States > Utah > Green River Basin (0.99)
- North America > United States > Kentucky > Illinois Basin > New Albany Shale Formation (0.98)
- (3 more...)
Summary Drilling activity has increased dramatically in unconventional shale gas reservoirs. The drilling fluid of choice in these shale plays is often nonaqueous-based fluid (NAF). While NAFs can provide advantages such as shale stabilization, lubricity, and contamination tolerance, environmental consequences and associated costs are an issue. These disadvantages cause operators to seek water-based muds (WBMs) for drilling many of these gas reservoirs. Despite some operational similarities, a wide variety of unique downhole conditions can be found in the shale plays. Shale mineralogy and bottomhole temperature (BHT) represent just two highly variable critical factors in unconventional gas reservoirs. Therefore, a single water-based solution for addressing shale plays globally is not a realistic option. Instead, a customized approach that delivers WBMs formulated specifically for a given shale play has been pursued. Customization relies on detailed analysis of the well parameters of a given shale play. This analysis includes not only the shale morphology and lithology but also well drilling program plans, environmental factors, and other reservoir-specific considerations. Applying appropriate drilling-fluid chemistries on the basis of this detailed analysis has led to the successful field deployment of a number of new shale fluids. Details of the process used for customizing a WBM for a shale play, as well as specific examples of new fluids developed for the Barnett, Fayetteville, and Haynesville shales, are presented in this paper. Full laboratory development and testing are described. Additionally, field-trial results are presented that show that specially designed WBMs can provide performance comparable to that of NAFs, but with enhanced environmental and economic benefits. Application of the customization process to develop WBMs for other shale plays around the globe is also discussed.
- North America > United States > Texas (1.00)
- North America > United States > Louisiana (0.91)
- North America > United States > Arkansas > Washington County > Fayetteville (0.30)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (1.00)
- North America > United States > Texas > Haynesville Shale Formation (0.99)
- North America > United States > Texas > East Texas Salt Basin > Cotton Valley Group Formation > Bossier Shale Formation (0.99)
- North America > United States > Oklahoma > Arkoma Basin > Fayetteville Shale Formation (0.99)
- (11 more...)
Shale gas is defined as natural gas occurring in shale formations. It is an unconventional energy resource, which has become an increasingly important source of natural gas globally and has the potential to grow as a major energy source in the next decade. However, production of shale gas remains technically and economically challenging. Having high total organic content and falling in the gas window (302 Fโ392 F), shale has sufficient potential to generate huge amounts of natural gas. Generally, natural gas is stored in a shale matrix, which is highly porous but has very poor permeability.
- North America > United States > Texas (0.79)
- North America > United States > Arkansas (0.52)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- (13 more...)
ABSTRACT: The increased drilling and production operations from unconventional reservoirs has elevated the need for extending our understanding on their complex petrophysical, acoustic, mechanical and failure behavior to incorporate their hydrocarbon production potential. In this paper, the elastic constants and Thomsen anisotropy parameters calculated from the wave velocity data have been compared to those determined from static stress cycling measurements and sonic logs where available. Selected shale anisotropy data from the literature has also been incorporated in the evaluation of the model to emphasize the prediction capability of the micromechanics model for shales. The magnitude of anisotropy has been shown to depend strongly on the organic content and presence of impurities in the matrix along with the fractures while smaller dependence was obtained on porosity. Thomsen parameters (e, and g) derived from oriented velocities also indicate frequency dependence that is rarely incorporated in either geomechanical or geophysical models and applications. 1. INTRODUCTION Nearly eighty percent of the sedimentary formations drilled for hydrocarbon exploration and production consist of shales pushing them to the forefront of the key research areas in geoscience and engineering in oil industry. The recent demand on the natural gas drilling and production in shale gas deposits have also raised level of interest on the organic-rich mudrocks, also known as black shales in addition to classical evaluation on wellbore and slope stability and seal/trap analysis. Organic richness, the type of kerogen, thermal maturity, expulsion or retention of hydrocarbons, presence of open fractures, and mechanical properties of the source rock determines the key differences observed in different shale formations and plays significant role on the outcome of if the shale formation has hydrocarbon producing potential or sealing characteristics. Shales consist of clay minerals, quartz, feldspar, carbonates, phosphates, and pyrite are also common inclusions (Potter et al., 2005). Mechanical, acoustic, petrophysical and failure properties of shales are highly impacted by shale lithology. The level of maturation of kerogen in shale has also important role on overall mechanical and failure properties as expulsion of gases introduces microcracks and fractures changing the texture of the shales. The alignment of clay platelets in the micro and meso-scale typically offers a key source of anisotropy introducing macroscale anisotropic characteristics of the shales. While seismic velocity response of shales to effective stress follows similar characteristics as in sandstones, clay bearing rocks reveal higher level of plasticity and anisotropy during burial and diagenesis history (Vernik and Landis, 1996). In addition to the contribution to anisotropic behavior, the clay fraction and in particular the kind and amount of the respective clay minerals present in shales significantly influences their chemical, acoustic, mechanical and failure behavior and is strongly influenced by physicochemical interactions between clay particles and pore fluids (Mese, 1995). While matching visual observations to micromechanical behavior is helpful, careful analysis of the mechanical responses of materials has been very enlightening for development of multi-scale micromechanical models and coupling their interaction with native formation fluids and altered states to drilling, drill-in, completion, workover and fracturing fluids.
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.87)
- North America > United States > Texas > East Texas Salt Basin > Cotton Valley Group Formation (0.98)
- North America > United States > Louisiana > East Texas Salt Basin > Cotton Valley Group Formation (0.98)
- North America > United States > Arkansas > East Texas Salt Basin > Cotton Valley Group Formation (0.98)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)