孔洞型碳酸盐岩储层饱和度建模新方法及应用

A novel saturation model of vuggy carbonate reservoirs and its application

碳酸岩复杂的孔隙结构和强烈的非均质性,导致传统的阿尔奇模型存在一定不适用性,主要体现在,m,n值的变化范围大。从岩石体积物理模型出发,设定n为常数,扩展m的含义并重新定义为孔隙结构指数,用它代替原Archie公式中胶结指数和饱和度指数对含水饱和度计算的影响。鉴于碳酸盐岩孔隙成因的复杂性和孔隙结构的复杂性,特别是裂缝型和溶蚀孔洞型碳酸盐岩储层取心困难,采用数值模拟手段考察碳酸盐岩孔隙结构指数m的影响因素及变化规律,主要包括孔隙结构特征参数孔喉比、孔隙度、泥质含量等因素对表征岩石导电性的F和岩石孔隙结构指数m的影响,又通过引入孔隙结构组分建立了变m的饱和度模型。应用效果表明新模型成功解决了四川磨溪溶蚀孔洞型碳酸岩储层水层段自由烃饱和度计算偏高的难题。

The traditional Archie model has certain inapplicability in carbonate reservoirs,due to the complex pore structure and strong heterogeneity.For example,the variable values of cement index （rn） and saturation index （n） often lead to a great deal of difficulties in saturation estimation.Based on the rock physics volume model,the saturation index （n） is assumed to be constant and redefine cementation exponent （rn） as a pore structure index.It is used to replace the effect of the original Archie cementation exponent and saturation index on water saturation calculation.Rock physical experiment is hard to be applied to the rocks from the complex reservoir.For the carbonate sample with fracture and dissolution vuggy,we can＇t obtain the cores easily.Therefore,the effects of the law of aspect ratio,porosity, clay content on the formation factor F and pore structure index of carbonate reservoir rocks are studied by numerical simulation.A new saturation model with variable index of pore structure is developed after the compositions of pore structure are employed in our research.The field logging data from one well in Sichuan Oilfield is processed using the new saturation model, and the applications of the new saturation model suggest that saturation precision has been improved.