缝洞型碳酸盐岩储层渗流特征研究

Seepage characteristics of fracture-cavity carbonate reservoir

缝洞型碳酸盐岩储层由于其独特的缝洞结构,取心时难以获得具有完整缝洞结构的天然岩心,限制了室内物理模拟实验的开展,阻碍了缝洞型油气藏流体渗流规律的研究。采用露头岩石制作缝洞型岩心,并通过制备的岩心研究缝洞型储层的渗流特性。结果表明:制作的缝洞型碳酸盐岩岩心可以用于室内实验研究;裂缝型岩心中微裂缝是控制气体流动的主要因素,油对气体渗流能力的影响高于水的影响,油降低气相流动作用比水的作用稍微显著些;缝洞型岩心中水会优先充填孔洞,导致油水同流区域较宽(0.496),缝洞型储层只要有部分裂缝未进水,气井就具有一定的产气能力,气相相对渗透率(Krg)大于0.05。气水相渗实验结果表明:缝洞型储层衰竭开发残余饱和度仅为0.01,油采收率较高;裂缝型储层受油和水影响,残余饱和度为0.11,相对缝洞型储层,其衰竭开发效果差。

Due to the unique fracture-cavity structure of fracture-cavity carbonate reservoir,it is difficult to obtain natural core with complete fracture-cavity structure when coring,which limits the development of labo⁃ratory physical simulation experiment and hindering the study of fluid flow law of fracture-cavity reservoir.To solve the above problems,the fracture-cavity core was made from the outcrop rock,and the seepage character⁃istics of the fracture-cavity reservoir were studied by using the prepared core.Results showed that the prepared fractured⁃cavity carbonate core could be used for laboratory experiments.The effect of oil on gas flow capacity was higher than that of water entry,and the effect of oil on gas flow reduction was slightly more significant than that of water.Fracture-cavity core water would preferentially filled the holes,leading to a wider oil-water flow area(0.496),indicating that as long as part of the fracture-cavity reservoir was not flooded,the gas well had a certain gas production capacity,Krg(Gas phase relative permeability)was over 0.05.The gas-water phase per⁃meability experiment showed that the residual saturation was only 0.01,and the oil recovery rate was high.Fractured reservoir was affected by oil and water,the residual saturation was 0.11,and the depletion develop⁃ment effect was worse than that of the fractured⁃cavity reservoir.