Abstract
A basin-wide simulation of wastewater injection is performed for the Fort Worth Basin. Uncertainties in geology and limited availability of injection data were two of the main challenges that were encountered during the course of the research. Simulation results show some spatial and temporal correlation between the pore pressure change and earthquakes occurrence. There are also areas of substantial predicted pore pressure increase where no seismicity is detected. The results suggest that proper assessment of seismic risk requires good subsurface geology (flow characteristics and pre-existing fault geometry) as well as well injection rate and pressure data. p>
1. BACKGROUND AND MOTIVATION
One of the very first studies on induced seismicity due to fluid injection was performed on the Denver earthquakes which occurred in the 1960’s due to injection into a disposal well at the Rocky Mountain Arsenal (RMA) [1]. Injection into the well at the RMA occurred between from 1962 to 1966 with a variable injection rate at different times during the injection periods [1, 2]. It was observed that seismic events continued to occur even after fluid injection was stopped [1, 2]. A few years following the event, an experiment conducted in Rangely, Colorado concluded that fluid injection can be used to control seismic events [3].
Since the 1960s, the link between earthquake clusters and disposal wells has been extensively examined [4]. Research has been done to correlate the various parameters, such as injection pressure and reservoir transmissivity, to the occurrence of induced earthquakes [1-4]. Yet, even though the mechanics behind induced earthquake is established, risk assessment and prediction is still difficult [1-4].
