scholarly journals A Numerical Investigation of the Hazardous Injection Area of Induced Earthquake during Hydraulic Fracturing

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Zhiyong Niu ◽  
Shiquan Wang ◽  
Hongrui Ma ◽  
Songbao Feng ◽  
Hengjie Luan ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Geothermal Energy ◽  
Hanging Wall ◽  
Injection Pressure ◽  
Geothermal Field ◽  
Fault Slip ◽  
Rock Fracturing ◽  
Induced Earthquakes ◽  
Induced Earthquake ◽  
The Stability

Hot dry rock (HDR) geothermal energy has many advantages, such as being renewable, clean, widely distributed, and without time and weather limitations. Hydraulic fracturing is usually needed for the exploitation of HDR geothermal energy. It has many hidden faults in the reservoir/caprock sequences. Injecting fluid into underground formations during hydraulic fracturing often induces fault slip and leads to earthquakes. Therefore, to well understand the induced fault slip and earthquakes is important for the applications and development of HDR geothermal exploitation. In this study, we investigated the hazardous injection area of the induced earthquakes during hydraulic fracturing. The study was based on a hydraulic fracturing test in Qiabuqia geothermal field in China. According to the field, a fault-surrounding rock-fracturing region system was developed to study the influences of fluid injection on the stability of the specific fault. A total of 60 hydraulic fracturing regions and 180 numerical experiments were designed. The results revealed that the hazardous injection regions that threaten the fault’s stability were near to the fault and concentrated on the following four areas: (a) above the top of the fault in underlying strata; (b) above the top of the hanging wall of the fault in underlying strata; (c) near to the fault planes in both footwall and hanging wall; (d) at the bottom of the footwall of the fault in underlying strata. The hazardous injection area can be controlled effectively by adjusting the injection pressure.

scholarly journals Study of Characteristics of Fault Slip and Induced Seismicity during Hydraulic Fracturing in HDR Geothermal Exploitation in the Yishu Fault Zone in China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Zhiyong Niu ◽  
Shiquan Wang ◽  
Hongrui Ma ◽  
Hengjie Luan ◽  
Zhouyuyan Ding
Keyword(s):  
Hydraulic Fracturing ◽  
Fault Zone ◽  
Geothermal Energy ◽  
Seismic Event ◽  
Geothermal Field ◽  
Fault Slip ◽  
Fault Reactivation ◽  
Geothermal System ◽  
Artificial Fracture ◽  
Yishu Fault Zone

Hot dry rock (HDR) geothermal energy has become promising resources for relieving the energy crisis and global warming. The exploitation of HDR geothermal energy usually needs an enhanced geothermal system (EGS) with artificial fracture networks by hydraulic fracturing. Fault reactivation and seismicity induced by hydraulic fracturing raise a great challenge. In this paper, we investigated the characteristics of fault slip and seismicity by numerical simulation. The study was based on a hydraulic fracturing project in the geothermal field of Yishu fault zone in China. It revealed that fluid injection during hydraulic fracturing can cause the faults that exist beyond the fluid-pressurized region to slip and can even induce large seismic event. It was easier to cause felt earthquakes when hydraulic fracturing was carried out in different layers simultaneously. We also examined the effects of the location, permeability, and area of the fracturing region on fault slip and magnitude of the resulting events. The results of the study can provide some useful references for establishing HDR EGS in Yishu fault zone.

scholarly journals Risk Assessment of Fracturing Induced Earthquake in the Qiabuqia Geothermal Field, China

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5977
Author(s):  
Kun Shan ◽  
Yanjun Zhang ◽  
Yanhao Zheng ◽  
Liangzhen Li ◽  
Hao Deng
Keyword(s):  
Principal Stress ◽  
Focal Mechanism ◽  
Maximum Principal Stress ◽  
In Situ Stress ◽  
Geothermal Field ◽  
Earthquake Risk ◽  
Maximum Magnitude ◽  
Induced Earthquakes ◽  
Induced Earthquake

In order to reduce the harm of induced earthquakes in the process of geothermal energy development, it is necessary to analyze and evaluate the induced earthquake risk of a geothermal site in advance. Based on the tectonic evolution and seismogenic history around the Qiabuqia geothermal field, the focal mechanism of the earthquake was determined, and then the magnitude and direction of in-situ stress were inversed with the survey data. At the depth of more than 5 km, the maximum principal stress is distributed along NE 37°, and the maximum principal stress reaches 82 MPa at the depth of 3500 m. The induced earthquakes are evaluated by using artificial neural network (ANN) combined with in-situ stress, focal mechanism, and tectonic conditions. The predicted earthquake maximum magnitude is close to magnitude 3.

scholarly journals THE BEHAVIOR CHARACTERISTICS OF A RESERVOIR LEVEE SUBJECTED TO INCREASING WATER LEVELS

2017 ◽  
Vol 23 (1) ◽  
pp. 15-27
Author(s):  
Chung-Won LEE ◽  
Yong-Seong KIM ◽  
Sung-Yong PARK ◽  
Dong-Gyun KIM ◽  
Gunn HEO
Keyword(s):  
Hydraulic Fracturing ◽  
Real Time ◽  
Pore Water ◽  
Volumetric Strain ◽  
Water Levels ◽  
The Core ◽  
The Stability ◽  
Centrifugal Model ◽  
Behavior Characteristics ◽  
Plastic Volumetric Strain

Centrifugal model testing has been widely used to study the stability of levees. However, there have been a limited number of physical studies on levees where the velocity of increasing water levels was considered. To investigate the behavior characteristics of reservoir levees with different velocities of increasing water levels, centrifugal model tests and seepage-deformation coupled analyses were conducted. Through this study, it was confirmed that increasing water levels at higher velocities induces dramatic increases in the displacement, plastic volumetric strain and risk of hydraulic fracturing occurring in the core of the levee. Hence, real-time monitoring of the displacement and the pore water pres­sure of a levee is important to ensure levee stability.

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.

The interplay of Malm carbonate permeability, gravity-driven groundwater flow, and paleoclimate – implications for the geothermal field and potential in the Molasse Basin (Southern Germany), a foreland-basin play

2021 ◽  
Author(s):  
Tom Vincent Schintgen ◽  
Inga Sigrun Moeck
Keyword(s):  
Groundwater Flow ◽  
Geothermal Energy ◽  
Foreland Basin ◽  
Geothermal Field ◽  
Molasse Basin ◽  
Carbonate Aquifer ◽  
Foreland Basins ◽  
Gravity Driven ◽  
The Impact ◽  
Subsurface Temperatures

Abstract The Molasse Basin in Southern Germany is part of the North Alpine Foreland Basin and hosts the largest accumulation of deep geothermal production fields in Central Europe. Despite the vast development of geothermal energy utilization projects especially in the Munich metropolitan region, the evolution of and control factors on the natural geothermal field are still debated. Especially seismic and deep well data from extensive oil and gas exploration in the Molasse Basin led to conceptual hydrogeological and thermal-hydraulic models. Corrected borehole-temperature data helped to constrain subsurface temperatures by geostatistical interpolation and facilitated the set-up of 3D temperature models. However, within the geothermally used Upper Jurassic (Malm) carbonate aquifer, temperature anomalies such as the Wasserburg Trough anomaly to the east of Munich and their underlying physical processes are yet poorly understood. From other foreland basins like the Alberta Basin in Western Canada, it is known that climate during the last ice age has a considerable effect even on subsurface temperatures up to two kilometres depth. Therefore, we study the impact of paleoclimatic changes on the Molasse Basin during the last 130 ka including the Würm glaciation. We consider the hydraulic and thermal effects of periglacial conditions like permafrost formation and the impact of the numerous glacial advances onto the Molasse Basin. The major difference between the thermal-hydraulic regime in the western and eastern parts of the Southern German Molasse Basin are delineated by calculating two contrasting permeability scenarios of the heterogeneously karstified Malm carbonate aquifer. Thermal-hydraulic modelling reveals the effect of recurrent glacial periods on the geothermally drillable subsurface, which is minor compared to the effect of permeability-related, continuous gravity-driven groundwater flow as a major heat transport mechanism. Practically, the results might help to reduce the exploration risk for geothermal energy projects in the Molasse Basin. More importantly, this study serves as a reference for the comparison and understanding of the interplay of high permeability aquifers, gravity-driven groundwater flow and paleoclimate in other orogenic foreland basins worldwide.

An Improved Closed-Loop Heat Extraction Method From Geothermal Resources

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Arash Dahi Taleghani
Keyword(s):  
Contact Area ◽  
Geothermal Energy ◽  
Closed Loop ◽  
Produced Water ◽  
Heat Extraction ◽  
Working Fluid ◽  
Induced Earthquakes ◽  
Geothermal Resources ◽  
Major Mechanism ◽  
Pressure Changes

Disposal of produced water and induced earthquakes are two major issues that have endangered development of the geothermal energy as a renewable source of energy. To avoid these problems, circulation of a low-boiling working fluid in a closed loop has been proposed; however; since the major mechanism in this method for heat extraction is conduction rather than convection and additionally the heat conduction is limited to the wellbore surface. To overcome this shortcoming, the formation can be fractured with high conductivity material (for instance, silicon carbide ceramic proppants or cements with silane and silica fume as admixtures) to artificially increase the contact area between the “working fluid” and the reservoir. Our calculations show that fracturing increases the contact area by thousand times, additionally, the fracturing materials reinforce and stressed the formation, which reduce the risk of seismic activity due to temperature or pressure changes of the system during the production.

Elastoplastic constitutive model for hydraulic aperture analysis of hydro-shearing in geothermal energy development

SIMULATION ◽  
2018 ◽  
Vol 95 (9) ◽  
pp. 861-872
Author(s):  
Yong Xiao ◽  
Jianchun Guo ◽  
Hehua Wang ◽  
Lize Lu ◽  
Mengting Chen
Keyword(s):  
Shear Strength ◽  
Hydraulic Fracturing ◽  
Geothermal Energy ◽  
Energy Development ◽  
Green Energy ◽  
Shear Displacement ◽  
Natural Fracture ◽  
Roughness Coefficient ◽  
Fracture Simulation ◽  
Hydraulic Aperture

Geothermal energy is renewable, clean and green energy generated and stored in the Earth’s crust. The most important consideration for geothermal energy development in non-hydrothermal scenarios is the use of hydraulic fracturing technology to establish an effective network pathway to conduct fluid from injectors to producers. Hydraulic fracturing in geothermal wells is referred to as hydro-shearing and the aim is to improve the conductivity of natural fractures. In this paper, linear elastic constitutive relationships and shear strength of discontinuities in the pre-peak region are initially considered. Based on the dynamic frictional weakening, a proved conductive aperture and the post-peak elastoplastic constitutive models are proposed to analyze the deformation and conductivity of the natural fracture. Simulation research has shown that the joint compressive strength (JCS) mainly affects the shear displacement and hardly affects the dilation. The joint roughness coefficient (JRC) is more important for decreasing the shear strength and improves the dilation aperture. To no one’s surprise, reducing the effective normal stress is the best way for increasing the shear displacement, dilation and conductivity of the natural fracture. Almost 90% of the slip displacement and dilation occurs after fracture shear failure. This displacement not only increases the hydraulic conductivity of the fracture, but also reduces the required surface pumping pressure.

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