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.

Seismic Reflection Processing coherently presents the physical concepts, mathematical details and methodology for optimizing results of reservoir modelling, under conditions of isotropy and anisotropy. The most common form of anisotropy - transverse isotropy - is dealt with in detail. Besides, practical aspects in reservoir engineering - such as interval isotropic or anisotropic properties of layered media; identifying lithology, pore-fluid types and saturation; and determining crack/fracture-orientations and density - form the core of discussions. This book incorporates significant new developments in isotropic and anisotropic reflection processing, while organizing them to improve the interpretation of seismic reflection data and optimizing the modeling of hydrocarbon reservoirs. It is written primarily as a reference and tutorial for graduate/postgraduate students and research workers in geophysics.

This book introduces practical seismic analysis techniques and evaluation of interpretation confidence, for graduate students and industry professionals - independent of commercial software products.

Exploration and characterization of conventional and unconventional reservoirs using seismic technologies are among the main activities of upstream technology groups and business units of oil and gas operators. However, these activities frequently encounter difficulties in quantitative seismic interpretation due to remaining confusion and new challenges in the fast developing field of seismic petrophysics. Seismic Petrophysics in Quantitative Interpretation shows how seismic interpretation can be made simple and robust by integration of the rock physics principles with seismic and petrophysical attributes bearing on the properties of both conventional (thickness, net/gross, lithology, porosity, permeability, and saturation) and unconventional (thickness, lithology, organic richness, thermal maturity) reservoirs. Practical solutions to existing interpretation problems in rock physics-based amplitude versus offset (AVO) analysis and inversion are addressed in the book to streamline the workflows in subsurface characterization. Although the book is aimed at oil and gas industry professionals and academics concerned with utilization of seismic data in petroleum exploration and production, it could also prove helpful for geotechnical and completion engineers and drillers seeking to better understand how seismic and sonic data can be more thoroughly utilized.

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.

Applied Techniques to Integrated Oil and Gas Reservoir Characterization: A Problem-Solution Discussion with Experts presents challenging questions encountered by geoscientists in their day-to-day work in the exploration and development of oil and gas fields and provides potential solutions from experts working in the field. Covers Amplitude Versus Offset (AVO), well-to-seismic tie, phase of seismic data, seismic inversion studies, pore pressure prediction, rock physics and exploration geological. The text examines challenges in the industry as well as the solutions and techniques used to overcome those challenges. Over the past several years there has been a growing integration of geophysical, geological, and reservoir engineering, production and petrophysical data to predict and determine reservoir properties. This includes reservoir extent and sand development away from the well bore, as well as in unpenetrated prospects, leading to optimization planning for field development. As such, geoscientists now must learn the technology, processes and challenges involved within their specific functions in order to complete day-to-day activities. Presents a thorough understanding of the requirements and issues of various disciplines in characterizing a wide spectrum of reservoirs Includes real-life problems and challenging questions encountered by geoscientists in their day-to-day work, along with answers from experts working in the field Provides an integrated approach among different disciplines (geology, geophysics, petrophysics, and petroleum engineering)