scholarly journals Towards a poroelastodynamics framework for induced earthquakes

2021 ◽  
Author(s):  
Saumik Dana
Keyword(s):  
Pore Pressure ◽  
Seismic Waves ◽  
Seismic Velocity ◽  
Earth Tides ◽  
Deformation Model ◽  
Induced Earthquakes ◽  
Wastewater Disposal ◽  
Seismogenic Faults ◽  
Future Work ◽  
Pressure Perturbations

Earthquakes can be triggered after pore pressure perturbations activate critically stressed seismogenic faults, where the perturbations can originate from natural causes like earth tides, rainfall, snowfall or anthropogenic causes like wastewater disposal, CO$_2$ injection, oil production, or groundwater extraction. As the faults slip under the action of the induced stress field, seismic waves are spawned from the hypocenter location. The waves propagate through the domain with a velocity that evolves with the evolving pressure and stress fields. The effect of these waves on the surrounding rock and the seismic velocity recorded on the seismograph can be modeled accurately only by incorporating elastodynamics in the deformation model coupled with flow-induced pressure perturbations. Hitherto, most of the literature in the realm has been limited to elastostatics coupled with flow within a prescribed/kinematic or quasi-dynamic fault slip framework. In this work, we provide a framework for coupling of wave propagation with pore pressure perturbations using one-way coupled poroelastodynamics in the presence of faults in which the pore pressure is specified apriori as a spatiotemporal function.We present results from analysis of displacement and velocity fields in the domain and tractions and slip evolution on the fault. The rendition of two-way coupled poroelastodynamics in which the flow problem is also solved is proposed as future work.

scholarly journals Pore Pressure Analysis for Distinguishing Earthquakes Induced by CO2 Injection from Natural Earthquakes

2020 ◽  
Vol 12 (22) ◽  
pp. 9723
Author(s):  
Chanmaly Chhun ◽  
Takeshi Tsuji
Keyword(s):  
Pore Pressure ◽  
Co2 Storage ◽  
Carbon Capture And Storage ◽  
Co2 Injection ◽  
Storage Site ◽  
Seasonal Fluctuations ◽  
Induced Earthquakes ◽  
Seismogenic Fault ◽  
Seismogenic Faults ◽  
Natural Earthquakes

It is important to distinguish between natural earthquakes and those induced by CO2 injection at carbon capture and storage sites. For example, the 2004 Mw 6.8 Chuetsu earthquake occurred close to the Nagaoka CO2 storage site during gas injection, but we could not quantify whether the earthquake was due to CO2 injection or not. Here, changes in pore pressure during CO2 injection at the Nagaoka site were simulated and compared with estimated natural seasonal fluctuations in pore pressure due to rainfall and snowmelt, as well as estimated pore pressure increases related to remote earthquakes. Changes in pore pressure due to CO2 injection were clearly distinguished from those due to rainfall and snowmelt. The simulated local increase in pore pressure at the seismogenic fault area was much less than the seasonal fluctuations related to precipitation and increases caused by remote earthquakes, and the lateral extent of pore pressure increase was insufficient to influence seismogenic faults. We also demonstrated that pore pressure changes due to distant earthquakes are capable of triggering slip on seismogenic faults. The approach we developed could be used to distinguish natural from injection-induced earthquakes and will be useful for that purpose at other CO2 sequestration sites.

Natural and artificial pore pressure variation for distinguishing earthquakes induced by CO2 injection from natural earthquakes

2021 ◽  
Author(s):  
Chanmaly Chhun ◽  
Takeshi Tsuji
Keyword(s):  
Pore Pressure ◽  
Carbon Capture ◽  
Carbon Capture And Storage ◽  
Co2 Injection ◽  
Storage Site ◽  
Seasonal Fluctuations ◽  
Induced Earthquakes ◽  
Seismogenic Fault ◽  
Seismogenic Faults ◽  
Natural Earthquakes

<p>It is important to distinguish between natural earthquakes and those induced by CO<sub>2</sub> injection at carbon capture and storage sites. For example, the 2004 M<sub>w</sub> 6.8 Chuetsu earthquake occurred close to the Nagaoka CO<sub>2</sub> storage site during gas injection, but we could not quantify whether the earthquake was due to CO<sub>2</sub> injection or not. Here, changes in pore pressure during CO<sub>2</sub> injection at the Nagaoka site were simulated and compared with estimated natural seasonal fluctuations in pore pressure due to rainfall and snowmelt, as well as estimated pore pressure increases related to remote earthquakes. Changes in pore pressure due to CO<sub>2</sub> injection were clearly distinguished from those due to rainfall and snowmelt. The simulated local increase in pore pressure at the seismogenic fault area was much less than the seasonal fluctuations related to precipitation and increases caused by remote earthquakes, and the lateral extent of pore pressure increase was insufficient to influence seismogenic faults. We also demonstrated that pore pressure changes due to distant earthquakes are capable of triggering slip on seismogenic faults. The approach we developed could be used to distinguish natural from injection-induced earthquakes and will be useful for that purpose at other CO<sub>2</sub> sequestration sites.</p><p>This research was published in “Sustainability”, https://doi.org/10.3390/su12229723.</p><p>Keywords: pore pressure; CO2 injection; induced earthquakes; seasonal earthquakes; remote earthquakes; seismogenic faults.</p>

scholarly journals Pore Pressure Analysis for Distinguishing Earthquakes Induced by CO2 Injection from Natural Earthquakes

2020 ◽  
Author(s):  
Chanmaly Chhun ◽  
Takeshi Tsuji
Keyword(s):  
Pore Pressure ◽  
Co2 Storage ◽  
Carbon Capture And Storage ◽  
Co2 Injection ◽  
Storage Site ◽  
Seasonal Fluctuations ◽  
Induced Earthquakes ◽  
Seismogenic Fault ◽  
Seismogenic Faults ◽  
Natural Earthquakes

It is important to distinguish between natural earthquakes and those induced by CO2 injection at carbon capture and storage sites. For example, the 2004 Mw 6.8 Chuetsu earthquake occurred close to the Nagaoka CO2 storage site during gas injection, but we could not quantify whether the earthquake was due to CO2 injection or not. Here we simulated changes of pore pressure during CO2 injection at the Nagaoka site and compared them with estimated natural seasonal fluctuations of pore pressure due to rainfall and snowmelt as well as estimated pore pressure increases related to remote earthquakes. We clearly distinguished changes of pore pressure due to CO2 injection from those due to rainfall and snowmelt. The simulated local increase in pore pressure at seismogenic fault area was much less than the seasonal fluctuations related to precipitation and increases caused by remote earthquakes, and the lateral extent of pore pressure increase was insufficient to influence seismogenic faults. We also demonstrated that pore pressure changes due to distant earthquakes are capable of triggering slip on seismogenic faults. The approach we developed could be used to distinguish natural from injection-induced earthquakes and will be useful for that purpose at other CO2 sequestration sites.

scholarly journals Physics-Based Relationship for Pore Pressure and Vertical Stress Monitoring Using Seismic Velocity Variations

2021 ◽  
Vol 13 (14) ◽  
pp. 2684
Author(s):  
Eldert Fokker ◽  
Elmer Ruigrok ◽  
Rhys Hawkins ◽  
Jeannot Trampert
Keyword(s):  
Pore Pressure ◽  
Seismic Velocity ◽  
Pressure Head ◽  
Groundwater Table ◽  
Surface Velocity ◽  
Seismic Velocities ◽  
Stress Monitoring ◽  
Near Surface ◽  
Velocity Variations ◽  
Velocity Changes

Previous studies examining the relationship between the groundwater table and seismic velocities have been guided by empirical relationships only. Here, we develop a physics-based model relating fluctuations in groundwater table and pore pressure with seismic velocity variations through changes in effective stress. This model justifies the use of seismic velocity variations for monitoring of the pore pressure. Using a subset of the Groningen seismic network, near-surface velocity changes are estimated over a four-year period, using passive image interferometry. The same velocity changes are predicted by applying the newly derived theory to pressure-head recordings. It is demonstrated that the theory provides a close match of the observed seismic velocity changes.

Spatial Evaluation of Pore Pressure Variations Related to Rainfall from Seismic Velocity Changes

2021 ◽  
Author(s):  
Rezkia Dewi Andajani ◽  
Takeshi Tsuji ◽  
Roel Snieder ◽  
Tatsunori Ikeda
Keyword(s):  
Pore Pressure ◽  
Negative Correlation ◽  
Ambient Noise ◽  
Seismic Velocity ◽  
Diffusion Mechanism ◽  
Velocity Change ◽  
Diffusion Parameters ◽  
The Status ◽  
Seismic Velocity Changes ◽  
Velocity Changes

<p>Crustal pore pressure, which could trigger seismicity and volcanic activity, varies with fluid invasion. Various studies have discussed the potential of using seismic velocity changes from ambient noise to evaluate pore pressure conditions, especially due to rainfall perturbations. Although the influence of rainfall on seismic velocity changes has been reported, consideration of the spatial influence on rainfall towards seismic velocity and its mechanism have not been well understood. We investigated the mechanism of rainfall-induced pore pressure diffusion in southwestern Japan, using seismic velocity change (Vs) inferred from ambient noise. We modeled pore pressure changes from rainfall data based on a diffusion mechanism at the locations where infiltration is indicated. By calculating the correlation between Vs changes and the modeled pore pressure with various hydraulic diffusion parameters, the optimum hydraulic diffusion parameter was obtained. We estimated the diffusion parameters with the highest negative correlation between pore pressure and Vs change because a negative correlation indicates pore pressure increase due to diffusion induced by groundwater load. Furthermore, the spatial variation of the hydraulic diffusivity infers the heterogeneity of the rocks in different locations. This finding suggests that the response of pore pressure induced by rainfall percolation depends on location.  We show that seismic velocity monitoring can be used to evaluate the status of pore pressure at different locations, which is useful for fluid injection, CO<sub>2</sub> wellbore storage, and geothermal development.</p>

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.

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