Article
Geosciences, Multidisciplinary
Tom Kettlety, James P. Verdon
Summary: The research found that the pore pressure increase caused by injection during hydraulic fracturing is generally considered to be the primary driver of induced seismicity, while in very tight reservoir rocks, unless a fracture network exists to act as a hydraulic conduit, the rate of diffusion may be too low to explain some microseismic sequences spatio-temporal evolution. Additionally, the study revealed that the fault triggering mechanisms during the PNR-1z and PNR-2 operations were different, with each operation activating faults with different orientations.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Geosciences, Multidisciplinary
Iain de Jonge-Anderson, Jingsheng Ma, Xiaoyang Wu, Dorrik Stow, David Griffiths
Summary: The production performance of a shale reservoir is directly influenced by the geomechanical characteristics of the formation, with the complexity of shale properties making it difficult to identify ideal target intervals for horizontal wells. For the UK's most promising shale gas target, the Bowland Shale, traditional long horizontal wells may not be feasible due to geological complexities, leading to the exploration of shorter, stacked horizontal well drilling alternatives for different stratigraphic intervals. By creating geomechanical zones within the Bowland Shale and identifying optimal intervals for hydraulic fracturing, potential landing zones with low effective stress and high brittleness can limit vertical hydraulic fracture growth and reduce the risk of well interference.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Mechanics
Feipeng Wu, Xianzhang Fan, De Li, Hongbin Yang, Jing Liu, Xiaojun Li
Summary: The main technology for removing deep plugging in unconsolidated sandstone reservoirs is deep penetrating hydraulic fracturing with chemical treatment. The study analyzed the effects of different viscosities and injection rates on fracture initiation and propagation, finding that high viscosity fracturing fluid at high injection rates can achieve hydraulic fracturing in high-permeability unconsolidated sandstone, and adjusting the viscosity and injection rate slightly higher than the threshold value can generate deep penetrating fractures in unconsolidated sandstones.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Geochemistry & Geophysics
Taeyeob Lee, Daein Jeong, Youngseok So, Daejin Park, Munseok Baek, Jonggeun Choe
Summary: An integrated workflow from geomechanics to reservoir simulation is proposed to accurately estimate performances of a shale gas reservoir by updating model parameters. Sensitivity analysis on parameters such as leakoff coefficient and horizontal stress anisotropy influences the propagation of fractures and gas productions. Calibration of the mechanical earth model (MEM) with microseismic measurements helps reduce uncertainties in production estimations.
Article
Geosciences, Multidisciplinary
Frantisek Stanek, Ge Jin, James Simmons
Summary: Hydraulic fracturing is crucial for unconventional reservoir production, and mapping induced seismicity plays a key role in understanding reservoir response and optimizing operations. This study focuses on using distributed acoustic sensing (DAS) to capture high-resolution microseismic data and develop a new methodology for imaging induced fractures. The proposed algorithm allows real-time mapping and tracking of fractures, leading to a better understanding of reservoir behavior.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Energy & Fuels
Saad Alafnan
Summary: This study investigates the impact of supercritical carbon dioxide injection on the geomechanics of kerogen in shale formations. It reveals that the injection of supercritical carbon dioxide alters the mechanical behavior of kerogen, leading to a decrease in ductility under applied stress. This research provides nano-scale insights into the advantages of using supercritical carbon dioxide to degrade the mechanical integrity of organic matters contained in shales, supporting the value of carbon dioxide sequestration in shale formations.
Article
Energy & Fuels
Arjun Kohli, Mark Zoback
Summary: The study investigated the relationship between stratigraphy, stress, and microseismicity at the Hydraulic Fracture Test Site-1, integrating data to construct a stress profile for the Wolfcamp sequence and predict pressure required for hydraulic fracture growth. Results identified pre-existing faults expected to slip during stimulation and determined microseismic focal plane mechanisms.
Article
Energy & Fuels
Andreas Michael
Summary: A new hybrid data-driven/physics-based approach is proposed to model hydraulic fracture (HF) initiation and early-phase propagation from perforated horizontal wells. A treatment-optimization scheme via oriented perforating is presented, considering the orientation of the induced HF initiation and the resultant formation breakdown pressure. The effectiveness of oriented-perforating can be compromised by fracturing fluid leakages around the casing's circumference. The hybrid-modeling approach is also used to estimate fracture initiation pressure (FIP) values for the seven shale plays studied.
GEOMECHANICS FOR ENERGY AND THE ENVIRONMENT
(2023)
Article
Engineering, Geological
Gayani Gunarathna, Bruno Goncalves da Silva
Summary: A series of hydraulic fracturing tests were conducted on prismatic granite specimens to investigate the effect of triaxial stress on cracking processes. The tests revealed that visible cracks are typically accompanied by white patching and are mainly intragranular when triaxial stresses are the same in all directions. Additionally, a graphical method identified micro-damage processes occurring earlier than visible methods, highlighting the importance of stress-state dependency on fracture initiation and breakdown pressures.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Geological
Bing Q. Li, Michela Casanova, Herbert H. Einstein
Summary: Hydraulic fracturing in crystalline rock, such as granite, for enhanced geothermal systems (EGSs) is studied to address uncertainties in the fracture initiation mechanisms. Experimental results show that hydraulic fractures initiate as tensile microcracks at the flaw tips and then propagate as a combination of tensile and shear microcracks. Numerical simulations confirm that fractures likely initiate in tension at flaw tips, even at relatively high far-field stresses.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Energy & Fuels
Bruna Teixeira Silveira, Deane Roehl, Eleazar Cristian Mejia Sanchez
Summary: In recent years, the oil and gas industry has explored unconventional reservoirs with increasing energy demand, adopting hydraulic fracturing techniques. Concerns about environmental contamination of aquifers due to this technique necessitate predicting fracture geometry. This paper proposes using an artificial neural network to predict hydraulic fracture and natural fractures interaction, with results showing excellent agreement with analytical solutions and numerical models.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
S. H. McKean, J. A. Priest, J. Dettmer, G. Fradelizio, D. Eaton
Summary: A Bayesian quantile regression method is used to separate microseismic events related to hydraulic fractures from induced events. This method allows for optimization of hydraulic treatments and mitigation of induced seismicity. A case study demonstrates the successful differentiation of faults connected to hydraulic fractures and faults solely related to induced seismicity.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Thermodynamics
Zhiqin Kang, Xing Jiang, Lei Wang, Dong Yang, Yulin Ma, Yangsheng Zhao
Summary: The authors used meter-scale oil shale as the experimental object to study the in situ heating technology for mining oil shale through steam injection. The results showed that hydraulic fracturing started at a pressure 0.34 times lower than the in situ stress, while high-temperature steam fracturing required a pressure 1.2 times higher than the in situ stress. The study also found that horizontal cracks were more easily formed in layered rock masses and that the thermal stress had a stronger influence on the fracture-inducing stress of the orebody.
Article
Energy & Fuels
Bailong Liu, Yu Liang, Takatoshi Ito
Summary: This study used numerical simulations to analyze the impact of hydraulic fracturing on the permeability of shale gas reservoirs. It was found that clay swelling produces shear cracks, while increasing pressure leads to the formation of tensile cracks and complex fracture networks, further enhancing permeability.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Bailong Liu, Yu Liang, Takatoshi Ito
Summary: This study used numerical simulations to investigate the effects of hydraulic fracturing on shale rock in shale gas development. The results indicate that hydraulic fracturing can induce the generation of micro-cracks, and the permeability of the rock increases significantly when a complex fracture network is formed. These findings help explain why low flow-back rate leads to high productivity in shale gas development.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)