Water-Rock Interaction in CO2 Sequestration in a Depleted Oil Reservoir Pilot Test

A field test of CO2 sequestration in the Neogene Minghuazhen Formation in the Bohai Bay Basin (BBB-Nm test) is presented, where the first Chinese pilot project of CO2 storage in a depleted oil reservoir was implemented. A total of 305 t CO2 was injected into the sandstone reservoir. The process of injection and pre/post-injection monitoring are described, especially for the geochemical monitoring in the field test. Results show that CO2 flux monitoring successfully tracked the injected CO2. Chemical analyses of post-injection brine samples indicate brine may have not been affected by CO2 injection during the monitoring period, which needs to be confirmed with further investigations before extending the results to deep saline aquifers.