Numerical model of pore-pressure diffusion associated with the initiation of the 2010-2011 Guy-Greenbrier, Arkansas earthquakes
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- 作者：P. O. Ogwari and S. P. Horton
- 刊名：Geofluids
- 出版年：2016
- 出版时间：December 2016
- 年：2016
- 卷：16
- 期：5
- 页码：954-970
- 全文大小：10997K
- ISSN：1468-8123
文摘
We model pore-pressure diffusion caused by pressurized waste-fluid injection at two nearby wells and then compare the buildup of pressure with the observed initiation and migration of earthquakes during the early part of the 2010–2011 Guy–Greenbrier earthquake swarm. Pore-pressure diffusion is calculated using MODFLOW 2005 that allows the actual injection histories (volume/day) at the two wells to diffuse through a fractured and faulted 3D aquifer system representing the eastern Arkoma basin. The aquifer system is calibrated using the observed water-level recovery following well shut-in at three wells. We estimate that the hydraulic conductivities of the Boone Formation and Arbuckle Group are 2.2 × 10−2 and 2.03 × 10−3 m day−1, respectively, with a hydraulic conductivity of 1.92 × 10−2 m day−1 in the Hunton Group when considering 1.72 × 10−3 m day−1 in the Chattanooga Shale. Based on the simulated pressure field, injection near the relatively conductive Enders and Guy–Greenbrier faults (that hydraulically connect the Arbuckle Group with the underlying basement) permits pressure diffusion into the crystalline basement, but the effective radius of influence is limited in depth by the vertical anisotropy of the hydraulic diffusivity. Comparing spatial/temporal changes in the simulated pore-pressure field to the observed seismicity suggests that minimum pore-pressure changes of approximately 0.009 and 0.035 MPa are sufficient to initiate seismic activity within the basement and sedimentary sections of the Guy–Greenbrier fault, respectively. Further, the migration of a second front of seismicity appears to follow the approximately 0.012 MPa and 0.055 MPa pore-pressure fronts within the basement and sedimentary sections, respectively.