高温高压油藏纳米颗粒提高CO2泡沫驱油效果实验

Experimental Study on Nano-Particle/CO2 Foam Flooding Effect in High-Temperature High-Pressure Reservoirs

吉林油田黑79区块小井距CO2驱试验区,储集层非均质性强,驱替平面不均衡,吸气剖面和吸水剖面变差,形成气窜通道,影响混相驱采收率。试验区油藏温度高达96.7℃,平均油层压力高达23.9 MPa,常规CO2泡沫体系的稳定性较差。提出了在高温高压油藏条件下的纳米颗粒/CO2泡沫体系,并在模拟油藏条件下对其进行应用性能评价。实验结果表明,在油藏条件下,纳米颗粒/CO2泡沫体系具有很好的耐温耐盐性;随着压力的升高,当CO2泡沫达到临界状态时,更容易与起泡剂溶液混合,形成更致密的网状结构,比在常压下形成的CO2泡沫性能更优。注入纳米颗粒/CO2泡沫体系,高渗层和低渗层的分流率都在50%左右,在驱油过程中,泡沫对高渗层能进行有效封堵,调整吸气剖面,从而提高低渗层的采收率。

The reservoir in the small well spacing CO2 flooding test area of the Block Hei 79,Jilin Oilfield is featured with serious heteroge neity,unbalanced displacement plane,poor gas entry and water injection profiles and gas channeling,which influence the recovery factor of miscible flooding.Due to the high reservoir temperature(96.7℃)and the average reservoir pressure reaching 23.9 MPa in the test area,the stability of the conventional CO2 foam system is poor.The paper proposes a nano particle/CO2 foam system under high temperature high pressure reservoir conditions and performs evaluation for its application performance under simulated reservoir conditions.The experiment results show that under the reservoir conditions,the nano particle/CO2 foam system has very good temperature resistance and salt tolerance,and with the increase of the reservoir pressure,the CO2 foam is easy to mix with foaming agent solution and a tighter net like structure forms when it reaches a critical state,whose performance is better than that under normal pressure.The shunt rates of both high permeability and low permeability intervals are about 50%after injecting the nano particle/CO2 foam system.During the displacement foam can effectively block high permeability interval and modify gas entry profile.Finally the recovery factor of low permeability interval can be improved.