基于蒙特卡洛法的边水油藏聚合物驱段塞优化

Optimization of Polymer Flooding Slug for Edge-water Reservoir based on the Monte Carlo Method

针对渤海A油田水驱含水率上升过快的问题,开展了先导试验井组聚合物驱提高采收率研究。应用正交设计方法对聚合物段塞大小和浓度进行设计,运用多元回归方法得到累计增油量和净现值及其影响因素间的函数模型,利用蒙特卡洛方法对函数模型进行分析预测,得到累计增油量的大小与概率(累计增油量为40.2×104m3时发生概率为90%,累计增油量为53.2×104m3时发生概率为10%)。研究得到影响因素由大到小依次为第2段塞体积、浓度和第1段塞体积,而后续保护段塞大小及第1段塞浓度对累计增油量影响相对较小;在最优段塞区间精细加密后,进一步得到推荐段塞结果:第1段塞体积为0.2倍注入孔隙体积,浓度为1 400 mg/L,第2段塞体积为0.4倍注入孔隙体积,浓度为900 mg/L,后续水驱体积为0.8倍注入孔隙体积。研究结果为先导井组的聚驱方案提供依据。

In order to address rapid increase of water cut during the water flooding in A- Oilfield in the Bohai Bay Basin,a pilot study was carried out on polymer flooding in well groups for EOR. The Orthogonal design method is used to work out the polymer slug size and concentration. The multiple regression method is used to acquire cumulative increase of oil production,net present value and function model of influencing factors. The Monte Carlo method is used to analyze and predict function model. The cumulative increase and probability of oil production are obtained( when cumulative increase of oil production was 40. 2 × 104m3 the probability was 90%,when cumulative increase of oil production was 53. 2 × 104m3 the probability was 90%).The influencing factors,in descending order,were the volume and the concentration of second slug as well as the volume of the first slug. However,subsequent protection of slugs and the concentration of the first slug had small effect on the cumulative increase of oil production. After fine infilling among optimal slugs,recommended slug results were obtained: the volume of first slug is 0. 2 of that the injected pore volume with concentration of 1 400 mg /L; the volume of second slug is 0. 4 of that the injected pore volume with concentration of 900 mg / L; the volume of subsequent water flooding is 0. 8 of that of the injected pore volume. The research results provide the criteria for polymer flooding scheme of pilot well groups.