缝洞型碳酸盐岩油藏注水井间干扰特征及其影响因素

Inter-well interferences and their influencing factors during water flooding in fractured-vuggy carbonate reservoirs

根据缝洞型油藏注采单元特征,设计并开展了9组注水干扰物理模拟对比实验,分析了注水干扰特征及其影响因素;基于渗流理论建立了注水干扰反演模型,研究了不同因素对干扰特征的影响规律。研究表明:注采井距、渗透率比值、溶洞储量、溶洞分布均对水驱干扰特征有较大影响;溶洞位于注采单元内渗透率相对较高的裂缝带上、井距相对较小的方向、距离生产井较近时,有利于注水开发;较大溶洞位于高渗或小井距方向时,低渗透或较大井距方向生产井早见水;溶洞在高渗方向且注采井间储量差异较大时,不同注采方向导流能力差异性对注水开发有利。注采井网构建或重组时,尽量使注水井不同注采方向上渗透率与溶洞储量成正比、注采井距与溶洞储量成反比;距离溶洞较近的井应为生产井、较远的井应为注水井。不同洞缝储量比对应不同的最优井距比和最优渗透率比值,且最优井距比和最优渗透率比值随洞缝储量比增大逐渐增加。

Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs, nine groups of experiments were designed and performed to analyze the interference characteristics and their influencing factors during water flooding. Based on percolation theory, an inversion model for simulating waterflooding interferences was proposed to study the influence laws of different factors on interference characteristics. The results show that well spacing, permeability ratio, cave size, and cave location all affect the interference characteristics of water flooding. When the cave is located in high permeability fractures, or in the small well spacing direction, or close to the producer in an injection-production unit, the effects of water flooding are much better. When the large cave is located in the high-permeability or small well spacing direction, the well in the direction with lower permeability or smaller well spacing will see water breakthrough earlier. When the cave is in the higher permeability direction and the reserves between the water injector and producer differ greatly, the conductivity differences in different injection-production directions are favorable for water flooding. When the injection-production well pattern is constructed or recombined, it’s better to make the reserves of caves in different injection-production directions proportional to permeability, and inversely proportional to the well spacing. The well close to the cave should be a producer, and the well far from the cave should be an injector. Different ratios of cave reserves to fracture reserves correspond to different optimal well spacings and optimal permeability ratios. Moreover, both optimal well spacing and optimal permeability ratio increase as the ratio of cave reserves to fracture reserves increases.