Measurement and Visualization of Tight Rock Exposed to CO(2) Using NMR Relaxometry and MRI

Understanding mechanisms of oil mobilization of tight matrix during CO(2) injection is crucial for CO(2) enhanced oil recovery (EOR) and sequestration engineering design. In this study exposure behavior between CO(2) and tight rock of the Ordos Basin has been studied experimentally by using nuclear magnetic resonance transverse relaxation time (NMR T(2)) spectrum and magnetic resonance imaging (MRI) under the reservoir pressure and temperature. Quantitative analysis of recovery at the pore scale and visualization of oil mobilization are achieved. Effects of CO(2) injection, exposure times and pressure on recovery performance have been investigated. The experimental results indicate that oil in all pores can be gradually mobilized to the surface of rock by CO(2) injection. Oil mobilization in tight rock is time-consuming while oil on the surface of tight rock can be mobilized easily. CO(2) injection can effectively mobilize oil in all pores of tight rock, especially big size pores. This understanding of process of matrix exposed to CO(2) could support the CO(2) EOR in tight reservoirs.