中低渗油藏自适应聚合物驱油体系的研究

70% of the crude oil were produced from mature oil fields, and 2/3 of the reserves discovered were highly permeable. However, the process to largely enhance oil recovery and the high-efficient displacing formulation have not been formed. Based on the fact that the recovery factor is relatively low and the viscosity of polymer solutions is significantly reduced, with the advancement of materials science and chemistry, the present proposal suggests a new idea, self-adaptive supramolecular polymers for enhancing oil recovery from medium- to low-permeability oil reservoirs. The properties of such polymer solutions will automatically satisfy the end use upon experiencing shear and elongation at the pore throats. Along with field flow fractionating, microfluidics will be used to correlate polymer coil size and the pore throat diameter to get more accurate matching factor, and to uncover the flowing behaviors of polymer solution in the porous media. In addition, templating polymerization will used for scaled-up manufacturing of such polymers, and the finalized recipe and optimized reaction parameters are expected to be obtained. Single polymer solution, surfactant-polymer binary system and alkali-surfactant-polymer ternary formulation will be tested to check their feasibility for the medium- to low-permeability oil reservoirs, and those can largely enhance oil recovery will be finalized for practical end use, which will underpin the field trial of these polymer-based systems for the EOR processes in the typical medium- to low-permeability oil reservoirs belonging to PetroChina.

中国自产原油的70%来自老油田，探明储量的2/3为低渗油藏，但老油田低渗油藏大幅度提高采收率的方法尚未形成，高效驱油体系尚未构建。本项目针对大庆III类和克拉玛依砾岩中低渗油藏化学驱采收率低、聚合物注入过程粘度损失严重等共性问题，以及储量丰富、适合化学驱的特点，结合材料科学的新进展，提出了中低渗油藏化学驱用自适应超分子聚合物的新思路；拟设计、合成系列剪切、拉伸自适应和温度、盐度自适应超分子聚合物，联合使用场流分析仪、微流控等手段构建聚合物线团尺寸和油藏孔喉的精确匹配关系，揭示模拟油藏条件下超分子聚合物渗流规律；研究自适应超分子聚合物的模板聚合制备方法，得到规模化制备的优化工艺条件；探索超分子聚合物驱、表面活性剂-超分子聚合物二元复合驱、碱-表面活性剂-超分子聚合物三元复合驱体系对中低渗油藏的适应性，形成大幅度提高中低渗油藏采收率的新型驱油体系，为中石油典型中低渗油藏化学驱提供关键技术支撑。

针对大庆III类和新疆油田中低渗油藏化学驱采收率低、聚合物注入过程黏度损失严重等共性问题，及储量丰富、适用化学驱的特点，结合材料学的新进展，提出了中低渗油藏化学驱用自适应超分子聚合物的新思路，制备了系列自适应聚合物，构建了高效驱油体系。首先，在模拟油藏环境下，建立了现用驱油聚合物（HPAM）链尺寸与微孔喉尺寸的匹配关系，可望为低渗区块的驱油方案提供参考。其次，研制了针对大庆III类油藏的渗透率自适应聚合物驱油剂，证实了其“超分子组装，可逆缔合”的结构特征和“分子量降低，黏度不降低”的性能特点，0.1wt.%的聚合物溶液在50mD的低渗条件下，比水驱提高采收率18.7%，比同浓度HPAM体系提高12.1%。第三，研制了针对大庆III类油藏的温度、矿化度自适应聚合物驱油剂，在浓度为0.1wt.%时即可实现热增黏；在100mD的低渗条件下，比水驱提高采收率13.6%，比同黏度HPAM体系提高4%；此类聚合物溶液在中渗高温高盐油藏（渗透率~200mD，温度>85oC，矿化度>32,000ng/L）可比水驱提高采收率10~15%，比同黏度HPAM体系提高3~5%。第四，研制了针对非均质中低渗油藏的CO2自适应聚合物驱油体系，实现了对热及CO2的协同响应增黏；在75mD/650mD的非均质条件下，基于此聚合物的水-CO2交替驱（WAG）比传统WAG驱提高采收率约22%。第五，研制了成胶时间从1天到42天可控的时间自适应聚合物凝胶，实现了深部成胶和注入剖面的均匀性。第六，对聚合物/表面活性剂二元复合驱提高采收率机理进行了深入探索，为构建自适应超分子聚合物/表面活性剂复合驱大幅度提高采收率体系奠定了理论基础。.基于基础理论的突破，渗透率自适应聚合物在大庆油田实现了规模化生产（>7000吨/年），并投入现场规模化试用（3605吨/年）。其中DS800已累计注入0.50 PV，单井日增油1.0t，采收率提高7.1%，预计最终可提高10.2%。DS2500已累计注入0.19 PV，单井日增油2.2t，采收率提高1.42%，预计最终可提高15%。.基于本项目的研究，共发表论文40篇，其中SCI论文37篇；国内外学术会议邀请报告9次；授权发明专利12件；培养博士研究生7名、硕士研究生7名。