Electromagnetic Imaging of CO2 Sequestration at an Enhanced Oil Recovery Site

Lawrence Livermore National Laboratory (LLNL) is currently involved in a long term study using time-lapse multiple frequency electromagnetic (EM) characterization at a waterflood enhanced oil recovery (EOR) site in California operated by Chevron Heavy Oil Division in Lost Hills, California (Figure 1). The petroleum industry’s interest and the successful imaging results from this project suggest that this technique be extended to monitor CO2 sequestration at an EOR site also operated by Chevron. The impetus for this study is to develop the ability to image subsurface injected CO2 during EOR processes while simultaneously discriminating between pre-existing petroleum and water deposits. The goals of this study are to combine laboratory and field methods to image a pilot CO2 sequestration EOR site using the cross-borehole EM technique, improve the inversion process in CO2 studies by coupling results with petrophysical laboratory measurements, and focus on new gas interpretation techniques. In this study we primarily focus on how joint field and laboratory results can provide information on subsurface CO2 detection, CO2 migration tracking, and displacement of petroleum and water over time. This study directly addresses national energy issues in two ways: 1) the development of field and laboratory techniques to improve in-situ analysis of oil and gas enhanced recovery operations and, 2) this research provides a tool for in-situ analysis of CO2 sequestration, an international technical issue of growing importance.