Abstract: Hybrid thermal-chemical recovery process is a typical follow-up technology applied in the later stage of steam recovery process in heavy oil reservoirs. During the hydrocarbon development process, the displacement and flow of the hybrid thermal system in porous media involve complex physical and chemical mechanisms, generally exhibiting highly non-isothermal and nonlinear laws, which is difficult to be characterized. Based on comprehensively considering the effect of the hybrid thermal system on reservoir rock and fluid properties, the paper establishes a non-isothermal phase field-controlled mathematical model for hybrid thermal-chemical recovery process in heavy oil reservoirs. Moreover, a regular porous media model and a porous media model reflecting the pore-throat characteristics of real rock samples have been constructed to simulate the displacement and flow characteristics of three different systems in porous media. The simulation results were validated against the results from microfluidic chip experiments. Focusing on the hybrid thermal recovery by CO₂-chemical agent as a representative case, it was finally clarified the effects of injected fluid temperature, rock wettability, interfacial tension, and gas-liquid ratio on the displacement and flow laws during hybrid thermal-chemical recovery process. Results show that the oil-water emulsification effect is the most typical mechanism for hybrid thermal-chemical recovery process, which has a significant influence on displacement and flow characteristics in porous media. Compared to the thermal injection recovery, hybrid thermal-chemical recovery process can effectively activate oil films on pore walls and expand the swept area . Specifically, the total swept area for the hybrid thermal recovery using CO₂-chemical agent is increased by approximately 12.5 % , and the average reservoir temperature is increased by nearly 15 ℃. The sweep efficiency of the hybrid thermal system can be significantly enhanced by increasing the injection temperature and gas-liquid ratio of the system while reducing contact angle and interfacial tension, among which the contact angle and interfacial tension have more significant effects.

Key words: heavy oil reservoir, hybrid thermal-chemical recovery process, displacement, non-isothermal flow, porous media

摘要： 热化学复合开发是稠油蒸汽热采开发后期代表性的接替技术,开发过程中由于热复合体系在多孔介质内的驱替与流动过程涉及复杂的物理化学机理,整体表现出高度的非等温非线性规律,表征难度较大。在充分考虑热复合体系对油藏岩石和流体物性影响的基础上,建立了稠油热化学复合开发的非等温相场控制数学模型,搭建了规则的多孔介质模型以及具有真实岩心孔喉特征的多孔介质模型,分别模拟了3种不同体系在多孔介质内的驱替与渗流特征,并基于微流控芯片的实验结果进行了模拟结果校验。最终,以CO₂-化学剂热复合开发方式为代表,明确了注入流体温度、岩石润湿性、界面张力及气液比等因素对热化学复合开发方式驱替与渗流规律的影响。研究结果发现,油水乳化效应是稠油热化学复合开发的最典型机理,对多孔介质内的驱替和渗流特征影响较大。相比单一注热开发,热化学复合开发可以有效启动孔壁油膜,扩大波及范围,其中,CO₂-化学剂热复合开发的总波及范围相比单一注热开发可扩大约12.5 % ,油层平均温度提高近15 ℃。通过提高热复合体系注入温度和气液比、降低接触角和界面张力可明显增大热复合体系的波及效率,其中,接触角和界面张力的影响更加显著。

关键词: 稠油油藏, 热化学复合开发, 驱替, 非等温渗流, 多孔介质