Ren Shaoran

Assessment of CO2 EOR and its geo-storage potential in mature oil reservoirs, Shengli Oilfield, China

Abstract Most oil reservoirs in the Shengli Oilfield area have entered middle and late development stages after nearly 40-years of production, and they are suitable for applying CO 2 EOR and carbon storage techniques. This study is aimed at assessing the potential of CO 2 EOR and storage in three large oil fields in the region based on the data of 183 mature oil reservoirs. The assessments include a regional geology assessment, storage site screening, reservoir screening for CO 2 EOR and EOR potential and storage capacity calculations. Many mature oil reservoirs are close to the main CO 2 sources and have good geographical and geological conditions for CO 2 storage. Of 41 reservoirs, 18 are suitable both for EOR and storage while 23 reservoirs were found suitable for storage as depleted oil reservoirs. The total EOR potential could be 999.72×10 4 t and the CO 2 storage potential could reach 9,553.92×10 4 t. The overall incremental oil recovery rate could be 5.76%. The greater OOIP the oil reservoir has, the greater potential for CO 2 EOR and storage it will have, and the more suitable for large-scale storage projects it will be. Those oil reservoirs suitable for CO 2 EOR with large OOIP will be the preferred sites for CO 2 storage. Many nearly depleted oil reservoirs with large OOIP can be considered as main sites for CO 2 storage in the near future.

Experimental characterizations and modeling of electrical resistance in hydrate bearing sediments

Electrical resistance is an important method in characterization of oil/gas reservoirs, and can also be applied to gas hydrate bearing formations. Formation of gas hydrate has many significant impacts on subsea sediments. Since electric ions are excluded in hydrate, hydrate formation can change the distribution and mobility of electrolytes in subsea sediments, which will affect the resistance of the sand matrix. In this study, experiments have been conducted to measure resistance in a large sand pack simulating the conditions of hydrate formation in sub sea sediments. The resistance of the sand matrix with various hydrate saturations is measured, and the results are discussed based on the Archies formulas for rocks. The effect of gas hydrate is revealed. The data presented in this paper can be used for the characterizations of the porosity and hydrate saturation in hydrate bearing subsea sediments during well logging.