高温高盐油藏聚合物微球-CO2复合驱的适应性

Adaptability of Polymer Microsphere-CO2 Composite Flooding in High Temperature and High Salinity Reservoirs

高温高盐非均质油藏调剖困难,高含水期无效水循环严重。本文以二乙烯苯、丙烯酰胺为单体,采用乳液聚合方法通过调整脱水山梨醇油酸脂的量制备了粒径为2.89数57.05μm的聚(二乙烯苯-丙烯酰胺)耐温耐盐微球。考察了合成聚合物微球的表面形貌、热稳定性、在水中的分散性、膨胀性及长期热稳定性,并进行了注入封堵性实验和驱替实验。研究结果表明:聚(二乙烯苯-丙烯酰胺)微球的耐温可达370℃,在2.69×10^5 mg/L矿化度水中具有良好的分散性能,90℃下粒径为10.81μm的聚合物微球24 h后膨胀率为12.85%,且具有长期热稳定性。在高温高盐环境下,粒径为10.81μm的聚合物微球在渗透率1700×10^-3μm^2的岩心中有良好的注入性和封堵性;水驱后,微球调剖+CO2驱的注入方式能更高效发挥微球的“调”和CO“2驱”的作用,驱油效果优于直接CO2驱和微球调剖+水驱,可以在高含水期提高原油采收率22.65%,高温高盐非均质油藏高含水期有必要进行“聚合物微球调剖+CO2驱”复合作业来提高采收率。

It is difficult to profile the high temperature and high salinity heterogeneous reservoirs,and the ineffective water circulation in the high water-cut period is serious. In this paper, the temperature-resistant and salt-resistant poly(divinylbenzene-acrylamide)microspheres with particle diameter of 2.89-57.05 μm were prepared by emulsion polymerization with divinylbenzene and acrylamide as monomers by controlling the dosage of sorbitan monooleate span80. The surface morphology,thermal stability,dispersibility and expansibility in water and long-term thermal stability of the polymer microspheres were investigated,and the injection plugging and displacement experiments were carried out. The results showed that the temperature resistance of poly(divinylbenzene-acrylamide)microspheres was up to 370℃,and it had good dispersion performance in 2.69 × 10^5 mg/L mineralized water. The expansion rate of polymer microspheres with particle size of 10.81 μm was 12.85% after24 hours at 90℃,and it had long-term thermal stability. In high temperature and high salt environment,the polymer microsphere with the particle size of 10.81 μm had good injectivity and sealing property in the core with the permeability of 1700 × 10^-3μm^2;After water flooding,the injection mode of"microsphere profile control + CO2 flooding"could play the role in microsphere profile control and CO2 flooding more efficiently,and the oil displacement effect was better than that of"direct CO2 flooding"and"microsphere profile control + water flooding",which could enhance oil recovery by 22.65% in high water cut period. Therefore,it is necessary to carry out "microsphere profile control + CO2 flooding"operations to enhance oil recovery during high water cut period in high-temperature and high-salt heterogeneous reservoirs.