CO 2 storage safety and leakage monitoring in the CCS demonstration project of Jilin oilfield, China

Jilin oilfield is conducting the first large‐scale demonstration project on CO 2 storage and enhanced oil recovery (EOR) in the northeast of China. A comprehensive monitoring program has been designed and deployed in the target reservoir of block H‐59 using a wide range of techniques to monitor the injection and production systems, the CO 2 migration fronts, and potential CO 2 leakage pathways. Tube fault detection, corrosion inhibitors, anti‐CO 2 corrosion cement, and production dynamic analysis have been adopted to guarantee the safety at the well site. CO 2 movement in the reservoir is detected mainly by gas tracer, electric spontaneous potential measurement, and fluid sampling. Near‐surface environmental monitoring is also conducted around the injection site. Field experience has shown that the monitoring targets should be focused on the reservoir, near‐surface, and injection and production systems. Applying monitoring techniques to ensure the integrity of wellbores can not only prevent the leakage of CO 2 , but also avoid the blind expansion of monitoring program scopes. It is reliable and economical to take full advantage of techniques based on wellbores to monitor CO 2 movement in oil reservoirs with dense well patterns. Up to April 2013, nearly 21.7 × 10-super-4 tons of CO 2 has been injected without obvious leakage caused by integrity failure of wells or the geological structure of reservoir. More than 96% of injected CO 2 has been safely stored with the rest of injected CO 2 normally breakthrough in the production wells. The preliminary monitoring experience obtained can provide valuable guidance for the future enlarged Jilin project and other CO 2 EOR and storage operations.