Geomechanics and Hydraulic Fracturing for Shale Reservoirs
Title | Geomechanics and Hydraulic Fracturing for Shale Reservoirs PDF eBook |
Author | Yu Wang |
Publisher | Scientific Research Publishing, Inc. USA |
Total Pages | 383 |
Release | 2020-07-01 |
Genre | Art |
ISBN | 1618968963 |
This book is intended as a reference book for advanced graduate students and research engineers in shale gas development or rock mechanical engineering. Globally, there is widespread interest in exploiting shale gas resources to meet rising energy demands, maintain energy security and stability in supply and reduce dependence on higher carbon sources of energy, namely coal and oil. However, extracting shale gas is a resource intensive process and is dependent on the geological and geomechanical characteristics of the source rocks, making the development of certain formations uneconomic using current technologies. Therefore, evaluation of the physical and mechanical properties of shale, together with technological advancements, is critical in verifying the economic viability of such formation. Accurate geomechanical information about the rock and its variation through the shale is important since stresses along the wellbore can control fracture initiation and frac development. In addition, hydraulic fracturing has been widely employed to enhance the production of oil and gas from underground reservoirs. Hydraulic fracturing is a complex operation in which the fluid is pumped at a high pressure into a selected section of the wellbore. The interaction between the hydraulic fractures and natural fractures is the key to fracturing effectiveness prediction and high gas development. The development and growth of a hydraulic fracture through the natural fracture systems of shale is probably more complex than can be described here, but may be somewhat predictable if the fracture system and the development of stresses can be explained. As a result, comprehensive shale geomechanical experiments, physical modeling experiment and numerical investigations should be conducted to reveal the fracturing mechanical behaviors of shale.
Geomechanics and Hydraulic Fracturing for Shale Reserviors
Title | Geomechanics and Hydraulic Fracturing for Shale Reserviors PDF eBook |
Author | Yu Wang |
Publisher | |
Total Pages | |
Release | 2020-07 |
Genre | |
ISBN | 9781618968951 |
Unconventional Reservoir Geomechanics
Title | Unconventional Reservoir Geomechanics PDF eBook |
Author | Mark D. Zoback |
Publisher | Cambridge University Press |
Total Pages | 495 |
Release | 2019-05-16 |
Genre | Technology & Engineering |
ISBN | 1108653111 |
Since the beginning of the US shale gas revolution in 2005, the development of unconventional oil and gas resources has gathered tremendous pace around the world. This book provides a comprehensive overview of the key geologic, geophysical, and engineering principles that govern the development of unconventional reservoirs. The book begins with a detailed characterization of unconventional reservoir rocks: their composition and microstructure, mechanical properties, and the processes controlling fault slip and fluid flow. A discussion of geomechanical principles follows, including the state of stress, pore pressure, and the importance of fractures and faults. After reviewing the fundamentals of horizontal drilling, multi-stage hydraulic fracturing, and stimulation of slip on pre-existing faults, the key factors impacting hydrocarbon production are explored. The final chapters cover environmental impacts and how to mitigate hazards associated with induced seismicity. This text provides an essential overview for students, researchers, and industry professionals interested in unconventional reservoirs.
Applied Petroleum Geomechanics
Title | Applied Petroleum Geomechanics PDF eBook |
Author | Jon Jincai Zhang |
Publisher | Gulf Professional Publishing |
Total Pages | 534 |
Release | 2019-06-15 |
Genre | Science |
ISBN | 0128148152 |
Applied Petroleum Geomechanics provides a bridge between theory and practice as a daily use reference that contains direct industry applications. Going beyond the basic fundamentals of rock properties, this guide covers critical field and lab tests, along with interpretations from actual drilling operations and worldwide case studies, including abnormal formation pressures from many major petroleum basins. Rounding out with borehole stability solutions and the geomechanics surrounding hydraulic fracturing and unconventional reservoirs, this comprehensive resource gives petroleum engineers a much-needed guide on how to tackle today’s advanced oil and gas operations. Presents methods in formation evaluation and the most recent advancements in the area, including tools, techniques and success stories Bridges the gap between theory of rock mechanics and practical oil and gas applications Helps readers understand pore pressure calculations and predictions that are critical to shale and hydraulic activity
Optimization of Hydraulic Fracture Stages and Sequencing in Unconventional Formations
Title | Optimization of Hydraulic Fracture Stages and Sequencing in Unconventional Formations PDF eBook |
Author | Ahmed Alzahabi |
Publisher | CRC Press |
Total Pages | 279 |
Release | 2018-07-03 |
Genre | Technology & Engineering |
ISBN | 1351618229 |
Shale gas and/or oil play identification is subject to many screening processes for characteristics such as porosity, permeability, and brittleness. Evaluating shale gas and/or oil reservoirs and identifying potential sweet spots (portions of the reservoir rock that have high-quality kerogen content and brittle rock) requires taking into consideration multiple rock, reservoir, and geological parameters that govern production. The early determination of sweet spots for well site selection and fracturing in shale reservoirs is a challenge for many operators. With this limitation in mind, Optimization of Hydraulic Fracture Stages and Sequencing in Unconventional Formations develops an approach to improve the industry’s ability to evaluate shale gas and oil plays and is structured to lead the reader from general shale oil and gas characteristics to detailed sweet-spot classifications. The approach uses a new candidate selection and evaluation algorithm and screening criteria based on key geomechanical, petrophysical, and geochemical parameters and indices to obtain results consistent with existing shale plays and gain insights on the best development strategies going forward. The work introduces new criteria that accurately guide the development process in unconventional reservoirs in addition to reducing uncertainty and cost.
Microseismic Imaging of Hydraulic Fracturing
Title | Microseismic Imaging of Hydraulic Fracturing PDF eBook |
Author | Shawn Mawell |
Publisher | SEG Books |
Total Pages | 212 |
Release | 2014-01-01 |
Genre | Science |
ISBN | 1560803150 |
Microseismic Imaging of Hydraulic Fracturing: Improved Engineering of Unconventional Shale Reservoirs (SEG Distinguished Instructor Series No. 17) covers the use of microseismic data to enhance engineering design of hydraulic fracturing and well completion. The book, which accompanies the 2014 SEG Distinguished Instructor Short Course, describes the design, acquisition, processing, and interpretation of an effective microseismic project. The text includes a tutorial of the basics of hydraulic fracturing, including the geologic and geomechanical factors that control fracture growth. In addition to practical issues associated with collecting and interpreting microseismic data, potential pitfalls and quality-control steps are discussed. Actual case studies are used to demonstrate engineering benefits and improved production through the use of microseismic monitoring. Providing a practical user guide for survey design, quality control, interpretation, and application of microseismic hydraulic fracture monitoring, this book will be of interest to geoscientists and engineers involved in development of unconventional reservoirs.
Geomechanical Studies of the Barnett Shale, Texas, USA
Title | Geomechanical Studies of the Barnett Shale, Texas, USA PDF eBook |
Author | John Peter Vermylen |
Publisher | Stanford University |
Total Pages | 143 |
Release | 2011 |
Genre | |
ISBN |
This thesis presents five studies of a gas shale reservoir using diverse methodologies to investigate geomechanical and transport properties that are important across the full reservoir lifecycle. Using the Barnett shale as a case study, we investigated adsorption, permeability, geomechanics, microseismicity, and stress evolution in two different study areas. The main goals of this thesis can be divided into two parts: first, to investigate how flow properties evolve with changes in stress and gas species, and second, to understand how the interactions between stress, fractures, and microseismicity control the creation of a permeable reservoir volume during hydraulic fracturing. In Chapter 2, we present results from adsorption and permeability experiments conducted on Barnett shale rock samples. We found Langmuir-type adsorption of CH4 and N2 at magnitudes consistent with previous studies of the Barnett shale. Three of our samples demonstrated BET-type adsorption of CO2, in contrast to all previous studies on CO2 adsorption in gas shales, which found Langmuir-adsorption. At low pressures (600 psi), we found preferential adsorption of CO2 over CH4 ranging from 3.6x to 5.5x. While our measurements were conducted at low pressures (up to 1500 psi), when our model fits are extrapolated to reservoir pressures they reach similar adsorption magnitudes as have been found in previous studies. At these high reservoir pressures, the very large preferential adsorption of CO2 over CH4 (up to 5-10x) suggests a significant potential for CO2 storage in gas shales like the Barnett if practical problems of injectivity and matrix transport can be overcome. We successfully measured permeability versus effective stress on two intact Barnett shale samples. We measured permeability effective stress coefficients less than 1 on both samples, invalidating our hypothesis that there might be throughgoing flow paths within the soft, porous organic kerogen that would lead the permeability effective stress coefficient to be greater than 1. The results suggest that microcracks are likely the dominant flow paths at these scales. In Chapter 3, we present integrated geological, geophysical, and geomechanical data in order to characterize the rock properties in our Barnett shale study area and to model the stress state in the reservoir before hydraulic fracturing occurred. Five parallel, horizontal wells were drilled in the study area and then fractured using three different techniques. We used the well logs from a vertical pilot well and a horizontal well to constrain the stress state in the reservoir. While there was some variation along the length of the well, we were able to determine a best fit stress state of Pp = 0.48 psi/ft, Sv = 1.1 psi/ft, SHmax = 0.73 psi/ft, and Shmin = 0.68 psi/ft. Applying this stress state to the mapped natural fractures indicates that there is significant potential for induced shear slip on natural fracture planes in this region of the Barnett, particularly close to the main hydraulic fracture where the pore pressure increase during hydraulic fracturing is likely to be very high. In Chapter 4, we present new techniques to quantify the robustness of hydraulic fracturing in gas shale reservoirs. The case study we analyzed involves five parallel horizontal wells in the Barnett shale with 51 frac stages. To investigate the numbers, sizes, and types of microearthquakes initiated during each frac stage, we created Gutenberg-Richter-type magnitude distribution plots to see if the size of events follows the characteristic scaling relationship found in natural earthquakes. We found that slickwater fracturing does generate a log-linear distribution of microearthquakes, but that it creates proportionally more small events than natural earthquake sources. Finding considerable variability in the generation of microearthquakes, we used the magnitude analysis as a proxy for the "robustness" of the stimulation of a given stage. We found that the conventionally fractured well and the two alternately fractured wells ("zipperfracs") were more effective than the simultaneously fractured wells ("simulfracs") in generating microearthquakes. We also found that the later stages of fracturing a given well were more successful in generating microearthquakes than the early stages. In Chapter 5, we present estimates of stress evolution in our study reservoir through analysis of the instantaneous shut-in pressure (ISIP) at the end of each stage. The ISIP increased stage by stage for all wells, but the simulfrac wells showed the greatest increase and the zipperfrac wells the least. We modeled the stress increase in the reservoir with a simple sequence of 2-D cracks along the length of the well. When using a spacing of one crack per stage, the modeled stress increase was nearly identical to the measured stress increase in the zipperfrac wells. When using three cracks per stage, the modeled final stage stress magnitude matched the measured final stage stress magnitude from the simulfrac wells, but the rate of stress increase in the simulfrac wells was much more gradual than the model predicted. To further investigate the causes of these ISIP trends, we began numerical flow and stress analysis to more realistically model the processes in the reservoir. One of our hypotheses was that the shorter total time needed to complete all the stages of the simulfrac wells was the cause of the greater ISIP increase compared to the zipperfrac wells. The microseismic activity level measured in Chapter 4 also correlates with total length of injection, suggesting leak off into the reservoir encouraged shear failure. Numerical modeling using the coupled FEM and flow software GEOSIM was able to model some cumulative stress increase the reservoir, but the full trend was not replicated. Further work to model field observations of hydraulic fracturing will enhance our understanding of the impact that hydraulic fracturing and stress change have on fracture creation and permeability enhancement in gas shales.