砾岩油藏聚合物驱后二元和三元复合驱的优选

Optimization of SP and ASP flooding after polymer flooding in conglomerate reservoir

新疆克拉玛依油区七东区发育砾岩油藏,经聚合物驱后虽已进入高含水期,但仍具有较高的挖潜、开发、再利用价值。二元和三元复合驱是砾岩油藏聚合物驱后提高采收率常用的开发方式。利用柱状天然岩心进行室内物理模拟实验,分析对比聚合物驱后二元和三元复合驱的注入压力、含水率、采收率以及微观剩余油分布特征,优化选择砾岩油藏聚合物驱后的开发方式。实验结果表明:二元和三元复合驱的含水率和注入压力相差较小,三元复合驱的采收率略高于二元复合驱;通过紫外荧光显微镜观察二元和三元复合驱后的岩心薄片,分析微观剩余油分布类型,发现三元复合驱后的剩余油分布类型以粒间吸附状为主,容易堵塞渗流通道,开采困难;而二元复合驱后的剩余油分布类型以颗粒表面吸附状为主,对储层伤害较小,对后续开发影响较小。综合考虑采收率、施工成本和储层伤害等情况,最终优选二元复合驱作为研究区聚合物驱后的开发方式。

Conglomerate reservoir,developed in the eastern No.7 district of Karamay oilfield in Xinjiang,has entered the high water content period after polymer flooding. However,it still has high potential and high value of development. SP and ASP flooding are two commonly used development models of enhanced oil recovery after polymer flooding in the conglomerate reservoir. The physical simulation experiment was carried out in the laboratory using natural core plugs. Injection pressure,water content,recovery ratio and remaining oil distribution of SP and ASP flooding after polymer flooding were analyzed. Development model after polymer flooding in the conglomerate reservoir was optimized. The experimental results show that the difference of water content and injection pressure between SP and ASP flooding was small,and the recovery ratio of ASP flooding was slightly higher than that of SP flooding. Moreover,core slice after SP or ASP flooding were observed by ultraviolet fluorescence microscopy,and the microscopic distribution type of the remaining oil was analyzed. It is found that the remaining oil after ASP flooding is mainly adsorbed in interparticle pore,which is likely to plug flow channel and hard to be driven. And the remaining oil after SP flooding is mainly adsorbed onto the surface of particles,which is less harmful to reservoir and the subsequent development. Considering the recovery ratio,construction cost and reservoir damage,SP flooding is chosen as the way to improve oil recovery after polymer flooding.