海上S 油田聚合物驱注采井网优化

海上S油田平面非均质性较强,经过多年聚合物驱开发,平面动用程度差异大,控水增油效果减弱,特别是聚合物驱后剩余油分布复杂,需通过注采井网优化进一步提高油田开发效果。依据海上S油田的沉积相分布特征与实际井网部署的关系,首先在室内建立了包括高、中、低渗透3个区域平面渗透率级差为3的物理模型,并在相同的注采条件下开展了5组不同井排距的物理模拟实验;然后采用油藏数值模拟方法,建立了与室内物理模型相对应的5个渗透率级差条件下油藏地质模型,每个地质模型设计了8个井排距模拟方案,共设计了40个井排距模拟方案。物理模拟实验结果表明:当平面渗透率级差为3时,井排距比为1.8,累积产油量最高,低渗透和高渗透储层2个方向上的驱替压力梯度基本一致,且微电极含油饱和度测试结果表明2个储层均能得到有效动用;通过油藏数值模拟进一步深入分析,得出了不同平面渗透率级差条件下的最优井排距,随着平面渗透率级差增大,最优井排距比也逐渐变大。在最优井排距认识的基础上,通过采用物理模拟实验和油藏数值模拟方法得出,水平井注直井采是最优的注采井网形式。

Optimization of injection-production pattern for polymer flooding in S offshore Oilfield

The plane heterogeneity of S offshore Oilfield is strong.After years of polymer flooding development,areal drain age degrees are heterogeneous,and the effect of water-controlling and oil-increasing is weakened.In particular,the remain ing oil distribution after the polymer flooding is complex,so the development effect of oilfield needs to be further improved by optimizing injection-production pattern.According to the relationship between the distribution characteristics of sedi mentary facies and well pattern in S Oilfield,the plane heterogeneous conceptual models from the high,medium and low permeability zones are established.Based on the above models,a physical simulation model with the plane permeability ra tio of 3 is established.Five groups physical simulation experiments of different well spacing are carried out under the same injection-production conditions.Then the reservoir geological models corresponding to the laboratory physical models at five permeability ratios are established by using the reservoir numerical simulation.Eight simulation schemes of well spac ing are designed for each geological model,so that the total number of simulation schemes of well spacing are equal to 40.The experiment results show that when the plane permeability ratio is 3,the cumulative oil production is the highest when the ratio of well spacing is 1.8.And pressure gradients in the low and high permeability reservoirs are basically the same,so microelectrode saturation test shows that the low permeability layer and the high permeability layer are both produced effec tively.Through deeper analysis of reservoir simulation results,the optimal well spacing under different plane permeability ratios is obtained.The optimal well spacing ratio gradually increases with the increase of plane permeability ratio.Finally,based on the optimal results,it is concluded that horizontal injection well and vertical production well form the best well pattern through the physical simulation experiment and reservoir numerical simulation.