scholarly journals Analysis of fluid pressure propagation in heterogeneous rocks: Implications for hydrologically-induced earthquakes

1998 ◽  
Vol 25 (13) ◽  
pp. 2329-2332 ◽  
Author(s):  
Ming-Kuo Lee ◽  
Lorraine W. Wolf
Keyword(s):  
Fluid Pressure ◽  
Induced Earthquakes ◽  
Heterogeneous Rocks ◽  
Pressure Propagation

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.

Large-Scale Migration Patterns of Wastewater-Induced Earthquakes in the Central U.S.

2020 ◽  
Author(s):  
Lisa Johann ◽  
Serge A. Shapiro
Keyword(s):  
Seismic Hazard ◽  
Large Volume ◽  
Large Scale ◽  
Oil And Gas ◽  
Fluid Pressure ◽  
Element Model ◽  
Strength Distribution ◽  
Correlation Technique ◽  
Induced Earthquakes ◽  
Injection Rates

&lt;p&gt;It is understood that the recent acceleration of seismic event occurrences in Kansas and Oklahoma, U.S., can be connected to the large-volume disposal of wastewater. These highly saline fluids are co-produced with oil and gas and are re-injected under gravity into the highly porous Arbuckle aquifer. Since 2015, injection rates have been decreasing. However, the seismic hazard in that region remains elevated. Furthermore, it has been noticed that some events in Kansas occur far from disposal wells.&lt;/p&gt;&lt;p&gt;To analyse spatio-temporal patterns between the fluid injection and earthquake locations, we applied a time-dependent 2D cross-correlation technique. This reveals a vectorial migration pattern of the seismic events. Whereas early events occur towards the east-sourtheast, later events are located preferably in northeastern direction of large volume injectors. With time, event locations migrate further in that direction. We explain this observation as well as measured Arbuckle pore pressures by a directional pore-fluid pressure diffusion and poroelastic stress propagation. This also follows from our principal two-dimension poroelastic finite element model which is of predictive power and identifies controlling parameters of the observations. These are mainly the permeability of the target injection formation and the seismogenic basement as well as the anisotropic permeability and the critical fault strength distribution. Our results lead to the conclusion that remote locations are destabilised also when injection rates are declining.&lt;/p&gt;&lt;p&gt;Thus, volume reductions may only provide a direct effect to lower earthquake rates locally. However, a state-wide decrease of the seismicity may require longer times such that the seismic hazard due to wastewater disposal induced seismicity may remain for decades.&amp;#160;&lt;/p&gt;

scholarly journals Geologic characterization of nonconformities using outcrop and whole-rock core analogues: hydrologic implications for injection-induced seismicity

2020 ◽  
Author(s):  
Elizabeth S. Petrie ◽  
Kelly K. Bradbury ◽  
Laura Cuccio ◽  
Kayla Smith ◽  
James P. Evans ◽  
...  
Keyword(s):  
Large Scale ◽  
Fluid Pressure ◽  
The United States ◽  
Crystalline Rock ◽  
Rock Properties ◽  
Induced Earthquakes ◽  
Injection Wells ◽  
Alteration Minerals ◽  
Reactive Fluids ◽  
Physical And Chemical

Abstract. The occurrence of induced earthquakes in crystalline rocks kilometres from deep wastewater injection wells poses questions about the influence nonconformity contacts have on the downward and lateral transmission of pore fluid pressure and poroelastic stresses. We hypothesize that structural and mineralogical heterogeneities at the sedimentary-crystalline rock nonconformity control the degree to which fluids, fluid pressure, and associated poroelastic stresses are transmitted over long distances across and along the nonconformity boundary. We examined the spatial distribution of physical and chemical heterogeneities in outcrops and whole-rock core samples of the great nonconformity in the midcontinent of the United States, capturing a range of tectonic settings and rock properties that we use to characterize the degree of historical fluid communication and the potential for future communication. We identify three end-member nonconformity types that represent a range of properties that will influence direct fluid pressure transmission and poroelastic responses far from the injection site. These nonconformity types vary depending on whether the contact is sharp and minimally altered, or if it is dominated by phyllosilicates or secondary non-phyllosilicate mineralization. We expect the rock properties associated with the presence or absence of secondary non-phyllosilicate mineralization and phyllosilicates to either allow or inhibit fractures to cross the nonconformity, thus impacting the permeability of the nonconformity zone. Our observations provide geologic constraints for modelling fluid migration and the associated pressure communication and poroelastic effects at large-scale disposal projects by providing relevant subsurface properties and much needed data regarding common alteration minerals that may interact readily with brines or reactive fluids.

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.

Stress-Drop Estimates for Induced Seismic Events in the Fort Worth Basin, Texas

2021 ◽  
Author(s):  
Seong Ju Jeong ◽  
Brian W. Stump ◽  
Heather R. DeShon ◽  
Louis Quinones
Keyword(s):  
Stress Drop ◽  
Source Parameters ◽  
Fluid Pressure ◽  
Corner Frequency ◽  
Mean Stress ◽  
Fort Worth ◽  
Induced Earthquakes ◽  
Fort Worth Basin ◽  
Generalized Inversion Technique ◽  
Stress Drops

ABSTRACT Earthquakes in the Fort Worth basin (FWB) have been induced by the disposal of recovered wastewater associated with extraction of unconventional gas since 2008. Four of the larger felt earthquakes, each on different faults, prompted deployment of local distance seismic stations and recordings from these four sequences are used to estimate the kinematic source characteristics. Source spectra and the associated source parameters, including corner frequency, seismic moment, and stress drop, are estimated using a modified generalized inversion technique (GIT). As an assessment of the validity of the modified GIT approach, corner frequencies and stress drops from the GIT are compared to estimates using the traditional empirical Green’s function (EGF) method for 14 target events. For these events, corner-frequency residuals (GIT−EGF) have a mean of −0.31 Hz, with a standard deviation of 1.30 Hz. We find consistent mean stress drops using the GIT and EGF methods, 9.56 and 11.50 MPa, respectively, for the common set of target events. The GIT mean stress drop for all 79 earthquakes is 5.33 MPa, similar to estimates for global intraplate earthquakes (1–10 MPa) as well as other estimates for induced earthquakes near the study area (1.7–9.5 MPa). Stress drops exhibit no spatial or temporal correlations or depth dependency. In addition, there are no time or space correlations between estimated FWB stress drops and modeled pore-pressure perturbations. We conclude that induced earthquakes in the FWB occurring on normal faults in the crystalline basement release pre-existing tectonic stresses and that stress drops on the four sequences targeted in this study do not directly reflect perturbations in pore-fluid pressure on the fault.

Extended Gassmann Equation with Dynamic Volumetric Strain: Modeling Wave Dispersion and Attenuation of Heterogenous Porous Rocks

Geophysics ◽  
2021 ◽  
pp. 1-97
Author(s):  
Luanxiao Zhao ◽  
Yirong Wang ◽  
Qiuliang Yao ◽  
Jianhua Geng ◽  
Hui Li ◽  
...  
Keyword(s):  
Fluid Pressure ◽  
Volumetric Strain ◽  
Wave Dispersion ◽  
Heterogeneous Porous Media ◽  
Porous Rocks ◽  
Analytical Methodology ◽  
Heterogeneous Rocks ◽  
Rock Characterization ◽  
Wave Induced ◽  
Dispersion And Attenuation

Sedimentary rocks are often heterogeneous porous media inherently containing complex distributions of heterogeneities (e.g., fluid patches, cracks). Understanding and modeling their frequency-dependent elastic and adsorption behaviors is of great interest for subsurface rock characterization from multi-scale geophysical measurements. The physical parameter of dynamic volumetric strain (DVS) associated with wave-induced fluid flow is proposed to understand the common physics and connections behind known poroelastic models for modeling dispersion behaviors of heterogeneous rocks. We derive the theoretical formulations of DVS for patchy saturated rock at mesoscopic scale and cracked porous rock at microscopic grain scales, essentially embodying the wave-induced fluid pressure relaxation process. By incorporating the DVS into the classical Gassmann equation, a simple but practical “dynamic equivalent” modeling approach, extended Gassmann equation, is developed to characterize the dispersion and attenuation of complex heterogeneous rocks at non-zero frequencies. Using the extended Gassmann equation, the effect of microscopic or mesoscopic heterogeneities with complex distributions on the wave dispersion and attenuation signatures can be captured. The proposed theoretical framework provides a simple and straightforward analytical methodology to calculate wave dispersion and attenuation in porous rocks with multiple sets of heterogeneities exhibiting complex characteristics. We also demonstrate that, with the appropriate consideration of multiple crack sets and complex fluids patches distribution, the modeling results can better interpret the experimental data sets of dispersion and attenuation for heterogeneous porous rocks.

scholarly journals Laboratory Study on the Effect of Fluid Pressurization Rate on Fracture Instability

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xinyao Wang ◽  
Quanchen Gao ◽  
Xiao Li ◽  
Dianzhu Liu
Keyword(s):  
Dominant Role ◽  
Fluid Pressure ◽  
Slip Mode ◽  
Permeability Evolution ◽  
Induced Earthquakes ◽  
Stick Slip ◽  
Pressurization Rate ◽  
Fracture Instability ◽  
Fluid Pressurization ◽  
Fracture Stability

Fluid injection-induced earthquakes have been a scientific and social issue of wide concern, and fluid pressurization rate may be an important inducement. Therefore, a series of stepwise and conventional injection-induced shear tests were carried out under different fluid pressurization rates and effective normal stresses. The results show that the magnitude of fluid pressure is the main factor controlling the initiation of fracture slipping. The contribution of fluid pressure heterogeneity and permeability evolution on the initiation of fracture slipping is different with the increase of fluid pressurization rate. When the fluid pressurization rate is small, permeability evolution plays a dominant role. On the contrary, the fluid pressure heterogeneity plays a dominant role. The increase of fluid pressurization rate may lead to the transition from creep slip mode to slow stick-slip mode. Under the laboratory scale, the fluid pressure heterogeneity causes the coulomb failure stress to increase by about one times than the predicted value at the initiation of fracture slipping, and the coulomb stress increment threshold of 1.65 MPa is disadvantageous to the fracture stability.

scholarly journals Geologic characterization of nonconformities using outcrop and core analogs: hydrologic implications for injection-induced seismicity

Solid Earth ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 1803-1821
Author(s):  
Elizabeth S. Petrie ◽  
Kelly K. Bradbury ◽  
Laura Cuccio ◽  
Kayla Smith ◽  
James P. Evans ◽  
...  
Keyword(s):  
Large Scale ◽  
Fluid Pressure ◽  
The United States ◽  
Crystalline Rock ◽  
Rock Properties ◽  
Type I ◽  
Induced Earthquakes ◽  
Injection Wells ◽  
Reactive Fluids ◽  
Physical And Chemical

Abstract. The occurrence of induced earthquakes in crystalline rocks kilometers from deep wastewater injection wells poses questions about the influence nonconformity contacts have on the downward and lateral transmission of pore-fluid pressure and poroelastic stresses. We hypothesize that structural and mineralogical heterogeneities at the sedimentary–crystalline rock nonconformity control the degree to which fluids, fluid pressure, and associated poroelastic stresses are transmitted over long distances across and along the nonconformity boundary. We examined the spatial distribution of physical and chemical heterogeneities in outcrops and core samples of the Great Unconformity in the midcontinent of the United States, capturing a range of tectonic settings and rock properties that we use to characterize the degree of past fluid communication and the potential for future communication. We identify three end-member nonconformity types that represent a range of properties that will influence direct fluid pressure transmission and poroelastic responses far from the injection site. These nonconformity types vary depending on whether the contact is sharp and minimally altered (Type 0), dominated by phyllosilicates (Type I), or secondary non-phyllosilicate mineralization (Type II). Our observations provide geologic constraints for modeling fluid migration and the associated pressure communication and poroelastic effects at large-scale disposal projects by providing relevant subsurface properties and much needed data regarding common alteration minerals that may interact readily with brines or reactive fluids.

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