低渗透油藏CO_2驱井网模式数值模拟

Numerical simulation of well pattern mode for CO2 flooding in low permeability reservoir

文中介绍了几种CO2驱常用井网模式的特点及适用范围,根据大庆油田外围某低渗区块地质与流体物性参数建立地质模型,在相态拟合的基础上对CO2驱不同井网模式进行了数值模拟研究。结果表明：该区五点井网的采出程度和地层压力保持程度要高于正方形反九点井网;五点井网中,排距与井距之比处于0.20~0.33和0.90~1.12范围内时采出程度较高,正方形井网的采出程度最低;储层中渗透率的各向异性、层内非均质性及天然裂缝的发育,使得同一井网密度下不同井排距方案的采出程度差异变大,并且会造成CO2的不均匀推进,影响采出程度。

The characteristics and sphere of application for different well pattern modes in CO2 flooding are introduced in this paper.Based on the geology and fluid parameters of one low permeability block in Daqing Oilfield,the geological model is established.The numerical simulation is researched after the phase matching.The results show that the recovery ratio and formation pressure of five-spot flooding pattern is higher than that of inverted nine-spot flooding pattern.When the ratio of the row spacing and well spacing is from 0.20 to 0.33 or from 0.90 to 1.12,the recovery efficiency is higher,the recovery efficiency of square well pattern is the lowest.The anisotropy and intralayer heterogeneity of permeability and the existence of natural fracture make the difference of the recovery ratio be large in different well row spacing and can cause the CO2 uneven driving,which will influence the recovery ratio.