CO2 flooding enhanced oil recovery (CO2-EOR) represents a significant technology in the low permeability reservoir. With the fractures and heterogeneity in low permeability reservoirs, CO2-EOR is susceptible to pessimistic gas channeling. Consequently, there is a need to develop conformance control materials that can be used in CO2-EOR. Herein, to address the challenges of low strength and poor stability of polymer gel in high temperature and low permeability reservoirs, a new organic/metal ion composite crosslinking polymer gel (AR-Gel) is reported, which is formed by low hydrolysis and medium to high molecular weight polymer (CX-305), organic crosslinking agent (phenolic resin), and aluminium citrate (Al(III)). The crosslinking of Al(III) with carboxyl group and organic/metal ion double crosslinking can construct a more complex and stable polymer gel structure on the basis of traditional chemical crosslinking, to cope with the harsh conditions such as high temperature. The structure–activity relationship of AR-Gel was revealed by rheology behavior and micro-morphology. The applicability of AR-Gel in reservoir was investigated, as was its strength and stability in supercritical CO2. The anti-gas channeling and enhanced oil recovery of AR-Gel were investigated using low permeability fractured cores, and the field process parameters were provided. The gel can be used to meet supercritical CO2 reservoirs at 110 °C and 20,000 mg/L salinity, with long-term stability over 60 days. The plugging rate of AR-Gel for fractured core was 97%, with subsequent CO2 flooding resulting in an enhanced oil recovery by 34.5%. AR-Gel can effectively control CO2 gas channeling and enhanced oil recovery. It offers a new material with high strength and temperature resistance, which is particularly beneficial in the CO2 flooding for the conformance control of oil field.

中文翻译：

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高温低渗透油藏抗CO2气窜有机/金属离子双交联聚合物凝胶的开发与评价


CO2驱提高石油采收率（CO2-EOR）是低渗透油藏的一项重要技术。由于低渗透油藏的裂缝和非均质性，CO2-EOR 容易受到悲观气体槽的影响。因此，需要开发可用于 CO2-EOR 的一致性控制材料。本文针对高温低渗透油藏中聚合物凝胶强度低、稳定性差的挑战，报道了一种由低水解中高分子量聚合物 （CX-305）、有机交联剂 （酚醛树脂） 和柠檬酸铝 （Al（III） 形成的新型有机/金属离子复合交联聚合物凝胶 （AR-Gel）。Al（III） 与羧基交联和有机/金属离子双交联可以在传统化学交联的基础上构建更复杂、更稳定的聚合物凝胶结构，以应对高温等恶劣条件。AR-Gel 的构效关系通过流变行为和微观形态揭示。研究了 AR-Gel 在储层中的适用性，以及它在超临界 CO2 中的强度和稳定性。使用低渗透性裂缝岩心研究了 AR-Gel 的抗窜流和提高采收率，并提供了现场工艺参数。该凝胶可用于满足 110 °C 和 20,000 mg/L 盐度下的超临界 CO2 储层，具有 60 天的长期稳定性。AR-Gel 对裂缝芯的封堵率为 97%，随后的 CO2 驱导致石油采收率提高了 34.5%。AR-Gel 可以有效控制 CO2 气体窜流并提高石油采收率。 它提供了一种具有高强度和耐温性的新材料，特别有利于 CO2 驱油田的一致性控制。