State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing, 100083, China.
Petroleum Exploration &Production Research Institute (PEPRIS), Sinopec, Beijing, 100083, China.
Sci Rep. 2017 Mar 10;7:44354. doi: 10.1038/srep44354.
Understanding mechanisms of oil mobilization of tight matrix during CO injection is crucial for CO enhanced oil recovery (EOR) and sequestration engineering design. In this study exposure behavior between CO and tight rock of the Ordos Basin has been studied experimentally by using nuclear magnetic resonance transverse relaxation time (NMR T) 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 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 injection. Oil mobilization in tight rock is time-consuming while oil on the surface of tight rock can be mobilized easily. CO injection can effectively mobilize oil in all pores of tight rock, especially big size pores. This understanding of process of matrix exposed to CO could support the CO EOR in tight reservoirs.
理解 CO2 注入过程中致密基质中油的运移机制对于 CO2 提高采收率（EOR）和封存工程设计至关重要。本研究通过在储层压力和温度条件下使用核磁共振横向弛豫时间（NMR T）谱和磁共振成像（MRI）实验研究了 CO2 与鄂尔多斯盆地致密岩之间的暴露行为。实现了孔隙尺度的回收定量分析和油运移的可视化。研究了 CO2 注入、暴露时间和压力对回收性能的影响。实验结果表明，CO2 注入可以逐渐将所有孔隙中的油驱替到岩石表面。致密岩中的油运移耗时较长，而致密岩表面的油则容易被驱替。CO2 注入可以有效驱替致密岩中所有孔隙中的油，尤其是大尺寸孔隙中的油。对暴露于 CO2 的基质过程的这种理解可以为致密储层中的 CO2 EOR 提供支持。
