CO2-EOR and Carbon Storage in Indian Oilfields: From Laboratory Study to Pilot Design

This work summarizes the prospect of EOR and sequestration using CO2 flooding from an Indian mature oil field in Assam through laboratory study, reservoir static modeling, dynamic simulation, pilot design, and techno-economic sensitivity studies. The geomodel was established by incorporating of contour maps, well positions and coordinates, well data and well logs, perforation depths and distribution of petrophysical properties as well as fluid properties. It was confirmed through PVT laboratory studies that CO2 injection can achieve the miscibility under reservoir conditions. The coreflooding test showed the significant incremental oil recovery by continuous CO2 injection and the residual oil saturation after miscible CO2 injection reached ~0.13PV. A fine scale geological model was built for entire reservoir and dynamic simulation work was performed on the geological model without upscaling. The history match of 51-year field production and pressure data in the whole reservoir was completed in a commercial simulator, and various development scenarios were investigated. Based on the results from CO2 EOR simulation study, we identified a pilot pattern area of ~ 60 acres with one injector and four producers. The CO2 was injected into reservoir at 150 metric ton per day for 5 years and cumulative injection volume is 15.4 BCF. Then the well is switched back to water injection afterward. Around 1 million STB incremental oil recovery was obtained in about 10 years, which corresponds to 11% of original oil in place in the flooded area. The CO2 utilization ratio is approximately 6 MCF/BBL. It is expected that CO2 flooding yields a pre-tax net cash flow of US dollars of 9.4 MM. CO2-EOR and storage in this mature field has a great techno-economic prospect. The investigation of CCUS opportunity and the substantial advancement in CO2 flood pilot design project have created an excitement in Indian Oil& Gas industry since the CCUS can significantly improve the domestic oil production from mature oilfields, and also reduce the carbon footprint in India. The volume of anthropogenic CO2 injection and storage in the reservoirs presents the great social and economic benefits for CCUS in India.