Do Injection‐Induced Earthquakes Rupture Away from Injection Wells due to Fluid Pressure Change?

2019 ◽  
Vol 109 (1) ◽  
pp. 358-371 ◽  
Author(s):  
Semechah K. Y. Lui ◽  
Yihe Huang
2020 ◽  
Author(s):  
Elizabeth S. Petrie ◽  
Kelly K. Bradbury ◽  
Laura Cuccio ◽  
Kayla Smith ◽  
James P. Evans ◽  
...  

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.


Solid Earth ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 1803-1821
Author(s):  
Elizabeth S. Petrie ◽  
Kelly K. Bradbury ◽  
Laura Cuccio ◽  
Kayla Smith ◽  
James P. Evans ◽  
...  

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.


2021 ◽  
Author(s):  
◽  
Chet Hopp

<p>In this thesis, we construct a four-year (2012–2015) catalog of microearthquakes for the Ngatamariki and Rotokawa geothermal fields in the Taupō Volcanic Zone of New Zealand, and use these data to improve the knowledge of reservoir behavior. These microearthquakes occur frequently, often every few seconds, and therefore provide a tool that we use to assess reservoir properties with dense spatial and temporal resolution as well as to illuminate the underlying processes of seismogenesis. Using a matched-filter detection technique we detect and precisely relocate nearly 9000 events, from which we calculate 982 focal mechanisms.  At Ngatamariki, these results constitute the first detailed analysis of seismicity at a newly-developed resource. It has been commonly assumed that induced shear on fractures increases reservoir permeability by offsetting asperities on either fracture wall, thereby propping the fracture open. During stimulation treatments of two boreholes (NM08 and NM09), borehole permeability experiences logarithmic growth. At NM08, this growth occurs for eight days in the absence of seismicity, while at NM09 only nine microearthquakes are observed during the one-month treatment. This suggests that hydro-shear, the process of inducing seismicity through increased pore pressure at critically-stressed fractures, is not the dominant mechanism of permeability increase at many geothermal wells. Instead, aseismic processes, likely thermal and overpressure induced fracture opening, dominate well stimulation in high-temperature geothermal settings.  At Rotokawa, the earthquake frequency-magnitude distribution (b-value) is positively correlated with both proximity to major injection wells and depth. In an inferred pressure compartment near injection well RK23, b is ~1.18, but is <1.0 elsewhere, suggesting a connection between increased pore-fluid pressure and small-magnitude events. In addition, throughout the reservoir b increases from a value of ~1.0 at injection depth to almost 1.5 two kilometers below the reservoir, consistent with observations at volcanic areas elsewhere, but opposing the conventional wisdom that b-value is inversely proportional to differential stress.  Finally, the 982 focal mechanism observations that we invert for stress show a normal faulting regime throughout both reservoirs. At Rotokawa, a lowering stress ratio, v, after reintroduction of injection well RK23 (v drops from 0.9 to 0.2 over six months) indicates that anisotropic reservoir cooling affects the reservoir stress state through a process of preferential stress reduction.</p>


2019 ◽  
Vol 24 (02) ◽  
pp. 169-174
Author(s):  
Yoke-Rung Wong ◽  
Sophie Sok Huei Tay ◽  
Ita Suzana Mat Jais ◽  
Hwa-Liang Leo ◽  
Chee-Fui Lieu ◽  
...  

Background: The interaction between wrist kinematics and synovial fluid pressure has yet to be studied. To our knowledge, this is the first study to determine the effect of scapholunate joint kinematics on synovial fluid pressure change using finite volume method. Methods: The carpal bones of a cadaveric hand were obtained from Computed Tomography (CT) scans. CT images of the carpal bones were segmented and reconstructed into 3D model. The 3D synovial fluid model between the scaphoid and lunate was constructed and then used for computational simulations. The kinematics data of scapholunate joint obtained from radioulnar deviation of the wrist was investigated. Results: It was found that the pressure in synovial fluid varied from -1.68 to 2.64 Pa with maximum pressure located at the scaphoid-fluid interface during the radial deviation. For ulnar deviation, the pressure increased gradually from the scaphoid-fluid interface towards the lunate-fluid interface (-1.37 to 0.37 Pa). Conclusions: This new computational model provides a basis for the study of pathomechanics of ligament injury with the inclusion of synovial fluid.


2018 ◽  
Vol 115 (8) ◽  
pp. E1720-E1729 ◽  
Author(s):  
Maria Kozłowska ◽  
Michael R. Brudzinski ◽  
Paul Friberg ◽  
Robert J. Skoumal ◽  
Nicholas D. Baxter ◽  
...  

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.


2020 ◽  
Vol 36 (4) ◽  
pp. 1995-2018 ◽  
Author(s):  
Bridger W Baird ◽  
Abbie B Liel ◽  
Robert E Chase

The rise in the number of anthropogenic small- to moderate-magnitude earthquakes in the central United States raises questions about the damageability of the built environment in such events. This study examines the performance of modern light-frame wood buildings, including single, multifamily, and commercial constructions, in earthquakes with moment magnitudes of 3–6, using dynamic analysis of building models subjected to ground motions recorded in past induced events in North America. We focus on first onset of damage, for example, wallboard or wallpaper cracking, and nails popping out. The results show that earthquakes with magnitudes less than 4–4.25 are unlikely to cause damage to modern constructions. However, moderate-magnitude events can cause damage over a wide geographic area (more than 30 mi from the earthquake epicenter, or 40 or more miles from a wastewater injection well). These results can be used to suggest setback distances between injection wells and certain neighborhoods or facilities, and magnitude thresholds for post-earthquake inspections.


2020 ◽  
Author(s):  
Lisa Johann ◽  
Serge A. Shapiro

&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;


2020 ◽  
Vol 91 (6) ◽  
pp. 3171-3181 ◽  
Author(s):  
Maomao Wang ◽  
Hongfeng Yang ◽  
Lihua Fang ◽  
Libo Han ◽  
Dong Jia ◽  
...  

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.


Author(s):  
Seong Ju Jeong ◽  
Brian W. Stump ◽  
Heather R. DeShon ◽  
Louis Quinones

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.


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