Shale oil contributes more than 60% to the US oil production. Shale oil production has been feasible because of technological development for horizontal wells with multistage hydraulic fracturing. However, after primary production, more than 90% of the oil is left behind in shale oil reservoirs due to ultra-low permeability. For an average well the oil production rates fall sharply in the first year because of the extremely low permeability, micro-fracture closure, and large flow resistance at the matrix-fracture interface. To sustain oil production from shale oil, it is essential to develop enhanced oil recovery (EOR) techniques for unconventional reservoirs. In this dissertation, lab experiments were conducted to investigate the effect of chemical treatment, gas huff-n-puff, and/or both on EOR in shale oil reservoirs. Surfactant treatment on shale was studied. Static adsorption experiments were performed to investigate the adsorption behavior of surfactant on shale samples. An additive model was built to estimate the adsorption capacity given the mineral composition and TOC of shale samples. A series of surfactant screening process, including aqueous stability tests, contact angle measurements, interfacial tension measurements, and spontaneous imbibition experiments, was used to compare the performance of surfactants at reservoir conditions. Surfactant blends were compared with single surfactants, and the surfactant blends showed improved oil recovery compared to most single surfactants. Chemical blends showed good EOR potential in Eagle Ford formation, and the effects of solvents in chemical blends were investigated via spontaneous imbibition process. Chemical blends with solvents showed improved recovery compared to the brine-only controlled case, and the Green Solvent showed the most promising results among the five solvents tested. Cyclic gas injection was investigated with CO2 and hydrocarbon gases. CO2 huffn-puff showed about 40% oil recovery, and it was observed that the huff pressure to which the cores were pressurized with CO2 did not affect the oil recovery significantly as long as the pressure was high enough. A combination of chemical blend with CO2 was more effective compared to pure CO2 huff-n-puff (40% → 64%). The hydrocarbon gas (60% C1 + 35% C2 + 5% C3) showed a similar effectiveness as CO2, which can be used to replace CO2 depending on availability and cost. Also, a numerical simulation model was built to investigate the key parameters in the gas huff-n-puff qualitatively. The learning from these simulations can be used for future experimental design

Fundamentals of Enhanced Oil Recovery Methods for Unconventional Oil Reservoirs, Volume 67 provides important guidance on which EOR methods work in shale and tight oil reservoirs. This book helps readers learn the main fluid and rock properties of shale and tight reservoirs—which are the main target for EOR techniques—and understand the physical and chemical mechanisms for the injected EOR fluids to enhance oil recovery in shale and tight oil reservoirs. The book explains the effects of complex hydraulic fractures and natural fractures on the performance of each EOR technique. The book describes the parameters affecting obtained oil recovery by injecting different EOR methods in both the microscopic and macroscopic levels of ULR. This book also provides proxy models to associate the functionality of the improved oil recovery by injecting different EOR methods with different operating parameters, rock, and fluid properties. The book provides profesasionals working in the petroleum industry the know-how to conduct a successful project for different EOR methods in shale plays, while it also helps academics and students in understanding the basics and principles that make the performance of EOR methods so different in conventional reservoirs and unconventional formations. Provides a general workflow for how to conduct a successful project for different EOR methods in these shale plays Provides general guidelines for how to select the best EOR method according to the reservoir characteristics and wells stimulation criteria Explains the basics and principles that make the performance of EOR methods so different in conventional reservoirs versus unconventional formations

Oil Recovery in Shale and Tight Reservoirs delivers a current, state-of-the-art resource for engineers trying to manage unconventional hydrocarbon resources. Going beyond the traditional EOR methods, this book helps readers solve key challenges on the proper methods, technologies and options available. Engineers and researchers will find a systematic list of methods and applications, including gas and water injection, methods to improve liquid recovery, as well as spontaneous and forced imbibition. Rounding out with additional methods, such as air foam drive and energized fluids, this book gives engineers the knowledge they need to tackle the most complex oil and gas assets. Helps readers understand the methods and mechanisms for enhanced oil recovery technology, specifically for shale and tight oil reservoirs Includes available EOR methods, along with recent practical case studies that cover topics like fracturing fluid flow back Teaches additional methods, such as soaking after fracturing, thermal recovery and microbial EOR

Fundamentals of Enhanced Oil and Gas Recovery from Conventional and Unconventional Reservoirs delivers the proper foundation on all types of currently utilized and upcoming enhanced oil recovery, including methods used in emerging unconventional reservoirs. Going beyond traditional secondary methods, this reference includes advanced water-based EOR methods which are becoming more popular due to CO2 injection methods used in EOR and methods specific to target shale oil and gas activity. Rounding out with a chapter devoted to optimizing the application and economy of EOR methods, the book brings reservoir and petroleum engineers up-to-speed on the latest studies to apply. Enhanced oil recovery continues to grow in technology, and with ongoing unconventional reservoir activity underway, enhanced oil recovery methods of many kinds will continue to gain in studies and scientific advancements. Reservoir engineers currently have multiple outlets to gain knowledge and are in need of one product go-to reference. Explains enhanced oil recovery methods, focusing specifically on those used for unconventional reservoirs Includes real-world case studies and examples to further illustrate points Creates a practical and theoretical foundation with multiple contributors from various backgrounds Includes a full range of the latest and future methods for enhanced oil recovery, including chemical, waterflooding, CO2 injection and thermal

Oil and Gas Chemistry Management Series brings an all-inclusive suite of tools to cover all the sectors of oil and gas chemicals from drilling, completion to production, processing, storage, and transportation. The third reference in the series, Recovery Improvement, delivers the critical chemical basics while also covering the latest research developments and practical solutions. Organized by the type of enhanced recovery approaches, this volume facilitates engineers to fully understand underlying theories, potential challenges, practical problems, and keys for successful deployment. In addition to the chemical, gas, and thermal methods, this reference volume also includes low-salinity (smart) water, microorganism- and nanofluid-based recovery enhancement, and chemical solutions for conformance control and water shutoff in near wellbore and deep in the reservoir. Supported by a list of contributing experts from both academia and industry, this book provides a necessary reference to bridge petroleum chemistry operations from theory into more cost-efficient and sustainable practical applications. Covers background information and practical guidelines for various recovery enhancement domains, including chapters on enhanced oil recovery in unconventional reservoirs and carbon sequestration in CO2 gas flooding for more environment-friendly and more sustainable initiatives Provides effective solutions to control chemistry-related issues and mitigation strategies for potential challenges from an industry list of experts and contributors Delivers both up-to-date research developments and practical applications, featuring various case studies

Gas Injection Methods, another critical volume in the Enhanced Oil Recovery series, addresses the latest research on various types of EOR. The book will help engineers focus on the latest developments in this fast-growing area. Different techniques are described, along with the latest technologies, such as nanotechnology applications, data mining and unconventional reservoirs. Sections cover an introduction to characterization techniques, properties, foam stability, injection in tight oil reservoirs and formation damage. Supported by a full spectrum of contributors, the book gives petroleum engineers and researchers the latest research developments and field applications to drive innovation for the future. Supported field case studies are included to support the bridge between research and practical application, making Enhanced Oil Recovery: Gas Injection Methods useful for both academics and practicing engineers. Helps readers understand the latest research and practical applications specific to foam flooding and gas injection Provides readers with the latest technology, including nanoparticle-stabilized foam for mobility control and carbon storage in shale oil reservoirs Teaches users about additional methods such as data mining applications and economic and environmental considerations

In recent years, production in unconventional reservoirs has increased exponentially due to technological breakthroughs in horizontal well completions. However, even with new technology, ultimate recovery after primary production in these reservoirs is extremely low (5-10% of original oil in place). The huff n’ puff process is considered to be a strong candidate for enhancing these notoriously-low recovery factors in unconventional reservoirs, especially those that are liquid-rich, in a cost-effective manner. Huff n’ puff is an enhanced oil recovery method in which one well alternates between injection, soaking, and production. Gas injection is often used in this scenario because of its high injectivity compared to water and its ability to develop miscibility with the reservoir oil. In this work, a recycled hydrocarbon gas was used due to its ease of accessibility within the target reservoir. In this work, the application of huff n’ puff to a liquid-rich shale reservoir with nanodarcy-range permeability was investigated both experimentally and numerically. A completely unique experimental setup was fabricated in order to execute oil recovery experiments on preserved core plugs taken from the target reservoir. In these experiments, it was shown that significant amounts of oil could be recovered after two huff n’ puff cycles lasting approximately one day each. Using propane as the injection gas resulted in higher recoveries when compared to the recycled gas due to enhanced miscibility with the oil. It was also shown that the ratio between soaking pressure and production pressure is a significant factor in recovering oil via huff n’ puff. An additional cycle was run with a longer soaking time, but no additional oil was recovered. A set of numerical reservoir models was also created to further investigate the recovery mechanisms in the huff n’ puff process. Lab-scale models were created in an attempt to replicate the experimental findings. The results showed that the recoveries seen in the experiments and simulations were very similar. Also, as long as injection took place above MMP, it was shown that the gas and oil mixed similarly in all cases regardless of pressure. Furthermore, lower production pressures allowed for more gas expansion and therefore better recovery, proving that production pressure alone may be an important parameter rather than the ratio between production and injection pressures. Field-scale models were also created. These models also showed that gas expansion plays a significant role in recovering oil. However, there were several key differences associated with sweep efficiency and the use of live oil versus dead oil.