Poroelastic modeling of wastewater injection in southern Kansas
Abstract
An increase in injection activity associated with energy production in southern Kansas starting in 2013 has been linked to the occurrence of more than 130,000 earthquakes (M -1.5 to 4.9) between 2014 and 2017 detected using a matched filter technique. Several studies suggest that the dramatic increase in seismicity rate is related to the injection of wastewater into the highly permeable Arbuckle formation. Most of the seismicity is located in the underlying crystalline basement (2 to 8 km of depth), for which hydrological properties and specific fault geometries are unknown. In addition, some earthquake clusters occurred relatively far (tens of kilometers) from the main injection wells. Therefore, the effect of pore pressure diffusion may not be sufficient to explain the relationship between the volume of injected fluids and the spatio-temporal evolution of seismicity in the region.
Recent studies show that, in addition to pore pressure changes, poroelastic stresses can play a significant role in triggering deep and distant earthquakes by fluid injection. Here, we test whether the combination of pore pressure and rock matrix stress evolution can explain the distribution of seismicity in southern Kansas between 2014 and 2017. We use a finite-element poroelastic model to calculate the coupled evolution of elastic stress and pore pressure in terms of Coulomb stress changes (ΔCFS) induced by wastewater injection from 102 wells located near the Kansas-Oklahoma border that were active between 2014 and 2016. Our first model includes isotropic hydrological parameters for both the Arbuckle formation (permeability of 10-13 m2), and the crystalline basement (permeability of 10-16 m2). Preliminary results show that the model can explain the spatio-temporal distribution of seismicity between 2 and 5 km of depth with ΔCFS values larger than 0.2 bar, while very low ΔCFS (< 0.1 bar) is predicted at greater depths. We present results for a range of hydrological parameters for both the Arbuckle formation and the crystalline basement. In addition, we adopt an anisotropic permeability for the crystalline basement that may explain the seismicity distribution at depths larger than 5 km, with high permeability values parallel to the strike direction of the main mapped faults in the region. The resulting constraints on permeability and diffusivity of the crystalline basement help quantify the seismic hazard connected with ongoing and future wastewater injections in southern Kansas.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S33C0605V
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGYDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8168 Stresses: general;
- TECTONOPHYSICS