Walkaway VSP Monitoring of CO2 Injection at the SACROC Oil Field in Texas

Geologic carbon sequestration requires injected CO2 be remotely and reliably monitored to ensure environmental and public safety. To study the capability of vertical seismic profiling (VSP) for monitoring migration of CO2 plume within geologic formations, one baseline and one repeat walkaway VSP surveys were conducted in July 2008 and April 2009, respectively, in the northern area of the Scurry Area Canyon Reef Operators Committee (SACROC) unit, an oil field located in West Texas. The objective of this work is to demonstrate combined enhanced oil recovery with geologic carbon sequestration, in collaboration with Kinder Morgan and the Southwest Regional Partnership on Carbon Sequestration that is supported by the U.S. Department of Energy and managed by the National Energy Technology Laboratory. The walkaway source line consists of 101 vibrator points and crosses the monitoring well along the north-south direction. The monitoring well is located approximately at the center of the walkaway source line. The total length of the source line is 3660 m. Fifteen-level three-component geophones are used to acquire the time-lapse VSP datasets. The geophones are placed at depths from 1524 m to 1737 m, and the oil reservoir is located approximately from 1820 m to 2100 m in depth. The time-lapse VSP data are pre-processed to balance the phase and amplitude of seismic events above the oil reservoir. We conduct imaging and scattering analysis using the pre-processed data. The results demonstrate that walkaway time-lapse VSP surveys with high-resolution imaging and scattering analysis can provide reliable information of injected CO2.