CO₂开发页岩油藏研究进展

Research Progress of Shale Reservoir Development with CO₂

张志超 李红雷 于春勇 韩继封 王慧娟 刘业新

ZHANG Zhichao LI Honglei YU Chunyong HAN Jifeng WANG Huijuan LIU Yexin

为了提高对应用CO2开发页岩油藏机理和规律的认识，系统论述了CO2在页岩油藏中的提高采收率机理，包括CO2对页岩油的快速增能、降黏、解堵、萃取和储层改造等机理；详述了CO2开发页岩油的技术特点和储层动用特征。随着CO2在页岩油藏注入量的增加，CO2与页岩油混合的p-T相图两相包络线区域变大，临界点上移，增加了页岩油藏的溶解气驱能量。由于页岩油藏中裂缝充分发育，CO2驱表现出严重的气窜，而CO2吞吐更适用于开发页岩油藏。吞吐提高页岩油采收率的本质是CO2向页岩基质中的强扩散、传质和补能作用，且有裂缝存在的油藏进行CO2混相吞吐效果好于无裂缝油藏的非混相吞吐。CO2开发页岩油时主要动用页岩油藏内0.008 μm以上孔隙内的油，且大孔隙内的油先被动用。提高CO2对页岩储层的动用孔隙下限的方法为提高注入压力或增加有效吞吐周期，从而增强CO2在油藏中的扩散和传质性。

In order to improve the understanding of mechanism and law of utilizing CO2 to develop shale oil reservoir，the EOR mechanisms of shale oil reservoir applied CO2 flooding was systematically discussed，including the rapid energy enhancement， viscosity reduction，plug removal，oil extraction and reservoir stimulation of shale oil reservoir，etc. Later，the technical characteristic and reservoir production characteristic of shale oil with CO2 development were described in detail. With the quantity increase of CO2 injection in shale oil reservoir，the two-phase envelope line area in p-T phase diagram of CO2 developed shale oil was enlarged，meanwhile，the critical point also moved up，which enhanced the energy of the reservoir with solution gas flooding. Due to the adequate development of fractures in shale reservoir，CO2 huff and puff was more suitable for the development of shale oil compared with CO2 flooding. The essence of CO2 huff and puff to enhance shale oil recovery was the strong CO2 diffusion，mass transfer and energy supplement effect in shale matrix. In addition，the miscible huff and puff effect in shale reservoir with fractures formation was better than that of immiscible huff and puff in reservoir without fractures. When CO2 was applied to develop shale reservoir，only the oil in the pores above 0.008 μm was mainly produced. Furthermore，the oil in the large pores of shale matrix was produced first. The method that enhanced the lower oil production limit in pore size by CO2 flooding in shale reservoir was to increase injection pressure or increase effective huff and puff cycle，thereby enhancing the diffusion and mass transfer ability of CO2 in shale reservoir.

10.19346/j.cnki.1000-4092.2023.03.024