scholarly journals Spatiotemporal changes in seismic velocity associated with hydraulic fracturing-induced earthquakes near Fox Creek, Alberta, Canada

2021 ◽  
Author(s):  
Adebayo Ojo ◽  
Honn Kao ◽  
Ryan Visser ◽  
Chet Goerzen
Keyword(s):  
Hydraulic Fracturing ◽  
Seismic Velocity ◽  
Induced Earthquakes ◽  
Spatiotemporal Changes

scholarly journals Sensitivity Analysis of Seismic Velocity and Attenuation Variations for Longmaxi Shale during Hydraulic Fracturing Testing in Laboratory

Energies ◽  
2017 ◽  
Vol 10 (9) ◽  
pp. 1393 ◽  
Author(s):  
Hongyu Zhai ◽  
Xu Chang ◽  
Yibo Wang ◽  
Ziqiu Xue ◽  
Xinglin Lei ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Hydraulic Fracturing ◽  
Seismic Velocity ◽  
Longmaxi Shale

Comprehensive Characterization and Mitigation of Hydraulic Fracturing-Induced Seismicity in Fox Creek, Alberta

SPE Journal ◽  
2021 ◽  
pp. 1-12
Author(s):  
Gang Hui ◽  
Shengnan Chen ◽  
Zhangxin Chen ◽  
Fei Gu ◽  
Mathab Ghoroori ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Hydraulic Fracture ◽  
Induced Seismicity ◽  
Mitigation Strategy ◽  
Moment Magnitude ◽  
Induced Earthquakes ◽  
Data Set ◽  
Comprehensive Characterization

Summary The relationships among formation properties, fracturing operations, and induced earthquakes nucleated at distinctive moments and positions remain unclear. In this study, a complete data set on formations, seismicity, and fracturing treatments is collected in Fox Creek, Alberta, Canada. The data set is then used to characterize the induced seismicity and evaluate its susceptibility toward fracturing stimulations via integration of geology, geomechanics, and hydrology. Five mechanisms are identified to account for spatiotemporal activation of the nearby faults in Fox Creek, where all major events [with a moment magnitude (Mw) greater than 2.5] are caused by the increase in pore pressure and poroelastic stress during the fracturing operation. In addition, an integrated geological index (IGI) and a combined geomechanical index (CGI) are first proposed to indicate seismicity susceptibility, which is consistent with the spatial distribution of induced earthquakes. Finally, mitigation strategy results suggest that enlarging a hydraulic fracture-fault distance and decreasing a fracturing job size can reduce the risk of potential seismic activities.

scholarly journals Maturity of nearby faults influences seismic hazard from hydraulic fracturing

2018 ◽  
Vol 115 (8) ◽  
pp. E1720-E1729 ◽  
Author(s):  
Maria Kozłowska ◽  
Michael R. Brudzinski ◽  
Paul Friberg ◽  
Robert J. Skoumal ◽  
Nicholas D. Baxter ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Fluid Pressure ◽  
Stress Transfer ◽  
Induced Earthquakes ◽  
Geologic History ◽  
B Values ◽  
Pressure Diffusion ◽  
Hydrologic Connections ◽  
Paleozoic Rocks ◽  
High Pressure Injection

Understanding the causes of human-induced earthquakes is paramount to reducing societal risk. We investigated five cases of seismicity associated with hydraulic fracturing (HF) in Ohio since 2013 that, because of their isolation from other injection activities, provide an ideal setting for studying the relations between high-pressure injection and earthquakes. Our analysis revealed two distinct groups: (i) deeper earthquakes in the Precambrian basement, with larger magnitudes (M > 2), b-values < 1, and many post–shut-in earthquakes, versus (ii) shallower earthquakes in Paleozoic rocks ∼400 m below HF, with smaller magnitudes (M < 1), b-values > 1.5, and few post–shut-in earthquakes. Based on geologic history, laboratory experiments, and fault modeling, we interpret the deep seismicity as slip on more mature faults in older crystalline rocks and the shallow seismicity as slip on immature faults in younger sedimentary rocks. This suggests that HF inducing deeper seismicity may pose higher seismic hazards. Wells inducing deeper seismicity produced more water than wells with shallow seismicity, indicating more extensive hydrologic connections outside the target formation, consistent with pore pressure diffusion influencing seismicity. However, for both groups, the 2 to 3 h between onset of HF and seismicity is too short for typical fluid pressure diffusion rates across distances of ∼1 km and argues for poroelastic stress transfer also having a primary influence on seismicity.

Shallow Faults Reactivated by Hydraulic Fracturing: The 2019 Weiyuan Earthquake Sequences in Sichuan, China

2020 ◽  
Vol 91 (6) ◽  
pp. 3171-3181 ◽  
Author(s):  
Maomao Wang ◽  
Hongfeng Yang ◽  
Lihua Fang ◽  
Libo Han ◽  
Dong Jia ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Sichuan Basin ◽  
Sedimentary Cover ◽  
Fluid Pressure ◽  
Earthquake Hazard ◽  
Induced Earthquakes ◽  
Coupled Flow ◽  
Cascading Effects ◽  
Pressure Diffusion ◽  
Underlying Mechanisms

Abstract Human activity-induced earthquakes are emerging as a global issue, and revealing its underlying mechanisms is essential for earthquake hazard mitigation and energy development. We investigated the relationship between the seismotectonic model and seismic sequences from moderate Mw 4.3 and Mw 5.2 earthquakes that occurred in February and September 2019, respectively, in the Weiyuan anticline of Sichuan basin, China. We found that the Mw 5.2 earthquake ruptured a back thrust of structural wedges and released most aftershocks near the wedge tip. However, the two foreshocks of the Mw 4.3 earthquake sequence occurred in hydrofractured Silurian shale at depth of 2.5–3 km, and the mainshock ruptured the overlying oblique tear fault at a depth of ∼1  km. Hydraulic fracturing in the sedimentary cover of this block may induce earthquakes through fluid pressure diffusion in the Silurian shale and through poroelastic effects on back thrusts within structural wedges, respectively. We assessed the hazard potential of four seismic sources in the Weiyuan block and suggest it is critical to conduct a coupled flow-geomechanics assessment and management on induced seismicity and related cascading effects in the densely inhabited and seismically active Sichuan basin.

Acoustic velocity and permeability of acidized and propped fractures in shale

Geophysics ◽  
2021 ◽  
pp. 1-55
Author(s):  
Jihui Ding ◽  
Anthony C. Clark ◽  
Tiziana Vanorio ◽  
Adam D. Jew ◽  
John R. Bargar
Keyword(s):  
Fluid Flow ◽  
Hydraulic Fracturing ◽  
Seismic Velocity ◽  
Rock Physics ◽  
Elastic Stiffness ◽  
Acoustic Velocity ◽  
S Wave ◽  
Fracture Permeability ◽  
Mechanical Fracture ◽  
Flow Pathways

From geochemical reactions to proppant emplacement, hydraulic fracturing induces various chemo-mechanical fracture alterations in shale reservoirs. Hydraulic fracturing through the injection of a vast amount and variety of fluids and proppants has substantial impacts on fluid flow and hydrocarbon production. There is a strong need to improve our understanding on how fracture alterations affect flow pathways within the stimulated rock volume and develop monitoring tools. We conducted time-lapse rock physics experiments on clay-rich (carbonate-poor) Marcellus shales to characterize the acoustic velocity and permeability responses to fracture acidizing and propping. Acoustic P- and S-wave velocities and fracture permeability were measured before and after laboratory-induced fracture alterations along with microstructural imaging through X-ray computed tomography and scanning electron microscopy. Our experiments show that S-wave velocity is an important geophysical observable, particularly the S-wave polarized perpendicular to fractures since it is sensitive to fracture stiffness. The acidizing and propping of a fracture both decrease its elastic stiffness. This effect is stronger for acidizing, and so it is possible that proppant monitoring will be masked by chemical alteration except when propping is highly efficient (i.e., most fractures are propped). However, fracture permeability is undermined by the softening of fracture surfaces due to acidizing, while greatly enhanced by propping. These contrasting effects on fluid flow in combination with similar seismic attributes indicate the importance of experiments to improve existing rock physics models, which must include changes to the rock frame. Such improvements are necessary for a correct interpretation of seismic velocity monitoring of flow pathways in stimulated shales.

Passive monitoring and 3D imaging of the bedrock response to the 2018 Espoo/Helsinki geothermal stimulation

2020 ◽  
Author(s):  
George Taylor ◽  
Gregor Hillers
Keyword(s):  
Seismic Velocity ◽  
Imaging Techniques ◽  
Body Wave ◽  
Coda Wave ◽  
Geothermal System ◽  
Enhanced Geothermal Systems ◽  
Induced Earthquakes ◽  
Borehole Data ◽  
Passive Monitoring ◽  
Short Period

&lt;p&gt;In recent years several deep geothermal energy projects have been forced to close following the occurrence of large seismic events associated with the stimulation of the surrounding bedrock. In 2018, an enhanced geothermal system (EGS) experiment performed in Helsinki, Finland concluded with no seismicity exceeding the threshold magnitude and thus provides an intriguing showcase for future stimulation experiments in similar environments. During the 49 days of the experiment, the five-stage injection of ~18,000 cubic meters water stimulated many thousands of earthquakes. Like in all previous stimulation cases the earthquake data constitute the primary source for the assessment of the scientific and operational aspects of the reservoir response. Here we apply ambient noise based monitoring and imaging techniques to data collected by 100 short period three-component stations that were organized in three large arrays consisting of nominally 25 stations, in addition to three small four-station arrays, and 10 single stations, during a 100 day period. We compute daily nine-component noise correlations between all stations pairs except for the intra-array pairs in a frequency range between 0.5 and 10 Hz. We measure waveform delays within our correlation functions as a function of frequency and lag time using the Continuous Wavelet Transform. We then invert these observations using a Markov chain Monte Carlo method to obtain the temporal variation in seismic velocity dv/v during the injection. By exploiting the variable spatial sensitivities of the surface- and body-wave components at different coda-wave lapse times and frequencies, we are able to image the medium response to the stimulation in both time and space. We compare the estimated seismic velocity variations to other observations such as H&lt;sup&gt;2&lt;/sup&gt;/V&lt;sup&gt;2&lt;/sup&gt;, as well as dv/v observations obtained from collocated borehole data. Importantly, we also compare the observed medium response to seismicity and pumping parameters. Our results suggest that we are able to resolve medium changes that are not solely associated with the induced earthquakes, but also potential signatures of fluid content or pressure changes in the bedrock. The combined observations of seismicity, pumping parameters and dv/v changes collected in this experiment can further advance passive monitoring techniques in the context of enhanced geothermal systems, and facilitate a more comprehensive analysis of fluid-rock interactions that may occur aseismically.&lt;/p&gt;

scholarly journals Research status of earthquake forecasting in hydraulic-fracturing induced earthquakes

2021 ◽  
Vol 34 (0) ◽  
pp. 1-13
Author(s):  
Qian WANG ◽  
◽  
Xinxin YIN ◽  
Changsheng JIANG ◽  
Cong JIANG ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Earthquake Forecasting ◽  
Induced Earthquakes ◽  
Research Status
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