The current state of shale gas reservoir dynamics demands understanding long-term production, and existing models that address important parameters like fracture half-length, permeability, and stimulated shale volume assume constant permeability. Petroleum geologists suggest that observed steep declining rates may involve pressure-dependent permeability (PDP). This study accounts for PDP in three potential shale media: the shale matrix, the existing natural fractures, and the created hydraulic fractures. Sensitivity studies comparing expected long-term rate and pressure production behavior with and without PDP show that these two are distinct when presented as a sequence of coupled build-up rate-normalized pressure (BU-RNP) and its logarithmic derivative, making PDP a recognizable trend. Pressure and rate field data demonstrate evidence of PDP only in Horn River and Haynesville but not in Fayetteville shale. While the presence of PDP did not seem to impact the long term recovery forecast, it is possible to determine whether the observed behavior relates to change in hydraulic fracture conductivity or to change in fracture network permeability. As well, it provides insight on whether apparent fracture networks relate to an existing natural fracture network in the shale or to a fracture network induced during hydraulic fracturing. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148240

Shale gas has become increasingly important to United States energy supply. During recent decades, the mechanisms of shale gas storage and transport were gradually recognized. Gas desorption was also realized and quantitatively described. Models and approaches special for estimating rate decline and recovery of shale gas wells were developed. As the strategy of the horizontal well with multiple transverse fractures (MTFHW) was discovered and its significance to economic shale gas production was understood, rate decline and pressure transient analysis models for this type of well were developed to reveal the well behavior. In this thesis, we considered a 0́Triple-porosity/Dual-permeability0́+ model and performed sensitivity studies to understand long term pressure drawdown behavior of MTFHWs. A key observation from this study is that the early linear flow regime before interfracture interference gives a relationship between summed fracture half-length and permeability, from which we can estimate either when the other is known. We studied the impact of gas desorption on the time when the pressure perturbation caused by production from adjacent transference fractures (fracture interference time) and programmed an empirical method to calculate a time shift that can be used to qualify the gas desorption impact on long term production behavior. We focused on the field case Well A in New Albany Shale. We estimated the EUR for 33 wells, including Well A, using an existing analysis approach. We applied a unified BU-RNP method to process the one-year production/pressure transient data and performed PTA to the resulting virtual constant-rate pressure drawdown. Production analysis was performed meanwhile. Diagnosis plots for PTA and RNP analysis revealed that only the early linear flow regime was visible in the data, and permeability was estimated both from a model match and from the relationship between fracture half-length and permeability. Considering gas desorption, the fracture interference will occur only after several centuries. Based on this result, we recommend a well design strategy to increase the gas recovery factor by decreasing the facture spacing. The higher EUR of Well A compared to the vertical wells encourages drilling more MTFHWs in New Albany Shale.

A comprehensive overview of the key geologic, geomechanical and engineering principles that govern the development of unconventional oil and gas reservoirs. Covering hydrocarbon-bearing formations, horizontal drilling, reservoir seismology and environmental impacts, this is an invaluable resource for geologists, geophysicists and reservoir engineers.

This dissertation focuses on multiscale analysis in shale to improve understanding of mechanical and transport properties in shale gas reservoirs. Laboratory measurements of the effects of constant confining pressure (CCP), and constant effective stress (CES) on permeability were coupled with multiscale finite element simulations and the development of a comprehensive apparent permeability model to study the mechanical behavior of shale and transport mechanisms in shale. Predicting long-term production from gas shale reservoirs is a challenging task due to changes in effective stress and permeability during gas production. Unlike coal, the variation of sorbing gas permeability with pore pressure in shale does not always feature a biphasic trend under a constant confining pressure. The present contribution demonstrates that the biphasic dependence of permeability on pore pressure depends on a number of physical and geometrical factors, each with a distinct impact on gas permeability. This includes pore size, adsorption isotherm, and the variation of gas viscosity with pore pressure.

Unconventional Shale Gas Development: Lessons Learned gives engineers the latest research developments and practical applications in today’s operations. Comprised of both academic and corporate contributors, a balanced critical review on technologies utilized are covered. Environmental topics are presented, including produced water management and sustainable operations in gas systems. Machine learning applications, well integrity and economic challenges are also covered to get the engineer up-to-speed. With its critical elements, case studies, history plot visuals and flow charts, the book delivers a critical reference to get today’s petroleum engineers updated on the latest research and applications surrounding shale gas systems. Bridges the gap between the latest research developments and practical applications through case studies and workflow charts Helps readers understand the latest developments from the balanced viewpoint of academic and corporate contributors Considers environmental and sustainable operations in shale gas systems, including produced water management

Pressure Transient Testing presents the fundamentals of pressure-transient test analysis and design in clear, simple language and explains the theoretical bases of commercial well-test-analysis software. Test-analysis techniques are illustrated with complete and clearly written examples. Additional exercises for classroom or individual practice are provided. With its focus on physical processes and mathematical interpretation, this book appeals to all levels of engineers who want to understand how modern approaches work. Pressure transient test analysis is a mature technology in petroleum engineering; even so, it continues to evolve. Because of the developments in this technology since the last SPE textbook devoted to transient testing was published, we concluded that students could benefit from a textbook approach to the subject that includes a representative sampling of the more important fundamentals and applications. We deliberately distinguish between a textbook approach, which stresses understanding through numerous examples and exercises dealing with selected fundamentals and applications, and a monograph approach, which attempts to summarize the state-of-the-art in the technology. Computational methods that transient test analysts use have gone through a revolution since most existing texts on the subject were written. Most calculations are now done with commercial software or by spreadsheets or proprietary software developed by users to meet personal needs and objectives. These advances in software have greatly increased productivity in this technology, but they also have contributed to a "black box" approach to test analysis. In this text, we attempt to explain what's in the box, and we do not include a number of the modern tools that enhance individual engineer productivity. We hope, instead, to provide understanding so that the student can use the commercial software with greater appreciation and so that the student can read monographs and papers on transient testing with greater appreciation for the context of the subject. Accordingly, this text is but an introduction to the vast field of pressure transient test analysis.