Microseismic event location for monitoring CO₂ injection using double-difference tomography

Microseismic event location for monitoring CO2 injection using double-difference tomography has been demonstrated. Increases in pore pressure and volume caused by CO2 injection will perturb the ambient stress field and possibly trigger brittle failure on small fractures or faults, resulting in micro earthquakes. Microseismic monitoring and several other techniques are being tested for tracking the movement and containment of CO2 injection at the Aneth oil Field in San Juan County, Utah. The waveforms cross correlation helps to precisely measure P- and S-wave differential arrival times, which constrains hypocentral locations in plan view and in depth. The method has been successfully applied to the method to microseismic event locations for monitoring CO2 injection at the Aneth oil field in Utah, and obtained preliminary, high-precision event locations and 3D velocity structures of the region between the events and the monitoring well.