Monitoring on CO 2 EOR and storage in a CCS demonstration project of JiMn Oilfield China

Jilin oilfield, located in Jilin Province of Northeast China, is conducting the first large scale demonstration project on CO 2 EOR and storage. During the first stage, CO 2 separated from a nearby natural gas reservoir (20-97% CO 2 content) is injected into the northern part of Hei-59 oil block. Currently, the targeted oil reservoir, with an area of 1.7 km 2 and oil reserve of 0.78×10 6 tons, has six CO 2 injectors and twenty-five production wells with an inverted seven-spot injector-producer pattern. Up to now, nearly 150,000 tons of CO 2 has been injected for a miscible flooding, and an expected incremental oil recovery of 10% would be achieved. In order to better evaluate the reservoir performance and ensure a safe injection and long-term storage of CO 2, a monitoring program has been designed and deployed to monitor the EOR performance and the state of CO 2 in the reservoir. The monitoring techniques used include CO 2 tracers to monitor gas breakthrough in production wells and flow of CO 2 across the reservoir, and bottom-hole pressure survey of producers to evaluate the miscibility effect on EOR combined with production data analysis. Geophysical techniques are also employed to detect possible fractures and their orientation and dimensions, which include electric spontaneous potential measurement and micro-seismic detections. Cross-well seismic is intended to monitor the flow and track the front of CO 2 between wells. Data of geochemical monitoring from produced water can be used to estimate the amount of CO 2 dissolved in reservoir fluids. CO 2 dissolution in formation water and residual oil is one of the main storage mechanisms, which can greatly enhance the safety and effectiveness of subsurface storage. In this paper, the results of reservoir monitoring applied in the oilfield are present and analyzed, and forward work will be focused on optimizing EOR performance and verification of the geo-capacity storage in the targeted reservoir. Copyright 2011, Society of Petroleum Engineers.