Total organic carbon (TOC) is one of the most important parameters for indicating the resource potential of unconventional shale reservoirs. Because of the low density and velocity of organic matter, some seismic attributes like P-wave impedance (Ip) and Vp/Vs ratio would respond to high TOC content. So we can use these seismic attributes to remotely identify organic-rich areas. However, these attributes are not equally efficient for all shale formations. The behavior of the geophysical response on TOC content may vary due to mineral variations of different shale plays. So, it is important to understand the mineral composition, study their impact on geophysical responses, and choose the right seismic attributes for the interpretation of a certain shale play. A rock physics modeling can be applied to link the in-situ rock parameters like mineral composition, TOC content, porosity etc. with the geophysical response. In this thesis work, I study the geophysical response of Barnett shale. In addition, I study the impacts of the mineral variations within an individual shale reservoir on geophysical response. Certain relationships between TOC and volume percentage of clay and quartz were observed, which should be taken into account when performing rock physics modeling, as opposed to assuming the mineral composition changing randomly.

Organic-rich shales can serve as both source rocks and reservoir rocks. They are becoming increasingly important exploration and exploitation targets; however our knowledge of organic-rich shale properties is poor. Mudrock line (Castagna et al., 1985) suggests that Vp/Vs ratios of shale are around 2, but Vp/Vs ratios of organic-rich shale vary from 1.5 to 1.7. What remains to be studied is what factors impact this difference. Understanding Vp-Vs relations for organic-rich source rock is vital for seismic characterization of shale reservoirs. This thesis explores several issues related to Vp-Vs relations of organic-rich shale, such as Vp/Vs ratio, P-wave and S-wave velocity anisotropies, and three Poisson's ratios in a TI medium. Parameters that affect the Vp/Vs ratio in organic-rich shale are studied in two parts: mineralogy and organic matter. First, we studied Vp/Vs ratios, P-impedance, and velocity anisotropies in three types of organic-rich shales: silica-rich, clay-rich, and calcareous shales. Vp/Vs ratios change with mineral composition. A simple two-layer model built with the Backus average is used to explain why silica-rich shale has the highest shear anisotropy and calcareous shale has the highest P-wave anisotropy among the three types of organic-rich shale. Well logging data are utilized to separate the effects of quartz, clay, and calcite on Vp/Vs, P-impedance, and density. Second, total organic carbon (TOC) and maturation of organic matter significantly affect shale properties, because of a large contrast between elastic properties of the organic and inorganic components. Basin and maturation models are built to simulate hydrocarbon generation during organic-rich shale evolution, which provides us the fundamentals for analyzing products and their concentrations in different maturation stages. The effect of organic matter with different maturity levels on immature, mature, and overmature shale properties are studied with rock physics models, which are based on effective medium theory. The immature and mature shale modeled results are plotted with the Bakken shale samples, which increase the credibility of the overmature model. The modeling results suggest that higher maturity level and TOC lead to lower Vp/Vs ratio and stronger anisotropy. When TOC is high, maturity level dominates; when TOC is low, TOC dominates.

The success of horizontal drilling and hydraulic fracturing has enabled the economic production of hydrocarbons from shale formations. However, wellbore instability and proppant embedment remain two major concerns during drilling and completion of wellbores in unconventional shale reservoirs. Both issues are largely controlled by shale-fluid interactions. Understanding the interactions of organic-rich shale with water-based fluids is the first step towards selecting appropriate drilling and fracturing fluids. The main objective of this study is to investigate the interactions of organic-rich shale with various water-based fluids. A series of measurements were performed to determine shale mineralogy, native water activity, fluid content, pore size distribution, Brinell hardness, Young's modulus, P-wave and S-wave velocities. It was shown that XRD and XRF yield consistent shale mineralogy, allowing us to make rapid determinations of shale mineralogy. Large variations in mineralogy were observed with shale samples from different formations. Even samples from the same well and at adjacent depths exhibited very different mineralogical makeup. The NMR T1/T2 ratio and T2 secular relaxation were used to distinguish pore fluids of different viscosity in pores of various sizes. A good correlation was established between the clay content and the amount of low-viscosity fluid in small pores, indicating that the water-saturated microporosity was in clay minerals. Combined N2GA and MICP measurements showed that a majority of the shale pores were found to be in the micropore to mesopore size range. Changes in shale mechanical properties were measured before and after shale samples came into contact with water-based fluids. The small degree of swelling and mechanical properties changes suggests that these organic-rich shales were only slightly sensitive to fluid exposure. Anisotropic swelling perpendicular and parallel to bedding planes could be due to the clay fabric anisotropy. The importance of using preserved shale samples was clearly demonstrated. Temperature and fluid pH were found to have significant impact on the reduction in shale mechanical stability after fluid exposure. Changes in both shale hardness and Young's modulus were observed with fluid exposure. Shales with higher clay content tend to experience greater reduction in modulus and hardness after contact with water-based fluids. A comparison between the measured fracture permeability damage and the calculated fracture permeability damage due to proppant embedment alone reveals that proppant embedment caused by shale softening is only partially responsible for the decrease in fracture permeability. Other mechanisms such as fines mobilization may be the dominant factors controlling fracture conductivity damage. Together these measurements allow us to rapidly screen drilling and fracturing fluids that are compatible with a particular shale by studying changes in shale mechanical properties before and after contact with water-based fluids. Potentially troublesome shales can be identified and possible solutions can also be evaluated using this measurement procedure.

This book details the analytical processes, and interpretation of the resulting data, needed in order to achieve a comprehensive source-rock evaluation of organic-rich shales. The authors employ case studies on Permian and Cretaceous shales from various Indian basins and other petroleum-bearing basins around the world to illustrate the key features of their organic-rich shale characterization methodology. These case studies may also help to identify potential zones within shale formations that could be exploited for commercial gas and/or oil production. Given its scope, the book will be of interest to all researchers working in the field of source-rock analysis. In addition, the source-rock evaluation techniques – and the various intricacies associated with them – discussed here offer valuable material for postgraduate geology courses.

Advances in theories, methods and applications for shale resource use Shale is the dominant rock in the sedimentary record. It is also the subject of increased interest because of the growing contribution of shale oil and gas to energy supplies, as well as the potential use of shale formations for carbon dioxide sequestration and nuclear waste storage. Shale: Subsurface Science and Engineering brings together geoscience and engineering to present the latest models, methods and applications for understanding and exploiting shale formations. Volume highlights include: Review of current knowledge on shale geology Latest shale engineering methods such as horizontal drilling Reservoir management practices for optimized oil and gas field development Examples of economically and environmentally viable methods of hydrocarbon extraction from shale Discussion of issues relating to hydraulic fracking, carbon sequestration, and nuclear waste storage Book Review: I. D. Sasowsky, University of Akron, Ohio, September 2020 issue of CHOICE, CHOICE connect, A publication of the Association of College and Research Libraries, A division of the American Library Association, Connecticut, USA Shale has a long history of use as construction fill and a ceramic precursor. In recent years, its potential as a petroleum reservoir has generated renewed interest and intense scientific investigation. Such work has been significantly aided by the development of instrumentation capable of examining and imaging these very fine-grained materials. This timely multliauthor volume brings together 15 studies covering many facets of the related science. The book is presented in two sections: an overview and a second section emphasizing unconventional oil and gas. Topics covered include shale chemistry, metals content, rock mechanics, borehole stability, modeling, and fluid flow, to name only a few. The introductory chapter (24 pages) is useful and extensively referenced. The lead chapter to the second half of the book, "Characterization of Unconventional Resource Shales," provides a notably detailed analysis supporting a comprehensive production workflow. The book is richly illustrated in full color, featuring high-quality images, graphs, and charts. The extensive index provides depth of access to the volume. This work will be of special interest to a diverse group of investigators moving forward with understanding this fascinating group of rocks. Summing Up: Recommended. Upper-division undergraduates through faculty and professionals.

The interpretation of geophysical data in exploration geophysics, well logging, engineering, mining and environmental geophysics requires knowledge of the physical properties of rocks and their correlations. Physical properties are a "key" for combined interpretation techniques. The study of rock physics provides an interdisciplinary treatment of physical properties, whether related to geophysical, geotechnical, hydrological or geological methodology. Physical Properties of Rocks, 2nd Edition, describes the physical fundamentals of rock properties, based on typical experimental results and relevant theories and models. It provides readers with all relevant rock properties and their interrelationships in one concise volume. Furthermore, it guides the reader through experimental and theoretical knowledge in order to handle models and theories in practice. Throughout the book the author focuses on the problems of applied geophysics with respect to exploration and the expanding field of applications in engineering and mining geophysics, geotechnics, hydrology and environmental problems, and the properties under the conditions of the upper Earth crust. Physical Properties of Rocks, Second Edition, guides readers through a systematic presentation of all relevant physical properties and their interrelationships in parallel with experimental and theoretical basic knowledge and a guide for handling core models and theories