Estimation of CO<sub>2</sub> Storage Capacity in Oil Reservoir after Waterflooding：Case Studies in Xinjiang Oilfield from West China

Abstract

CO2 storage in oil reservoirs is an important method to reduce Greenhouse Gas Emission. It was proven to have a great CO2storage capacity and economic potentials via EOR by injecting CO2into oil reservoirs. In China, most oil reservoirs went through waterflooding, and have high water saturation at present. The storage capacity in these oil reservoirs can be estimated on base of material balance method which considers the volume of displaced water and oil, CO2 sweep efficiency, and CO2 solution in oil and water. Case studies of four reservoirs selected from Xinjiang oilfield in China are conducted, the theoretical storage capacity and effective storage capacity is estimated. The results show that oil reservoir can provide much larger storage capacity, and oil and water displacement and CO2dissolution in remaining oil and water are the main forms of CO2storage in oil reservoirs after waterflooding. It’s a great option to inject CO2 into these reservoirs to reduce Greenhouse Gas emission, and the detailed storage capacity is worth further studies.