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应用阿尔奇(Archie)关系式计算油藏中的含水饱和度(S_w)需要胶结指数m和饱和度指数n。而确定这两个参数通常是很困难的,特别是在碳酸盐岩油藏中。Maute等(1972)提出了估算m和n的一种新方法。在岩心阿尔奇参数估算(CAPE)法中,是通过使由岩心得到的S_w与由阿尔奇关系式推导的S_w之间的误差达到最小的办法来确定m和n值的。因为岩心数据通常是得不到的,因此,Asquith和Saha(1991)用介电含水饱和度(S_(xo))表示由岩心得到的含水饱和度。在本文中,作者用三种方法—非线性、线性和m-孔隙度变换法确定使水饱和度误差为极小的m和n值。利用美国得克萨斯州Ward县Glorieta-Clearfork白云岩的资料时,因非线性法能使由介电测定得到的S_(xo)与由阿尔奇公式推得的S_(xo)之间的误差达到最小。用非线性和线性方法确定的m和n不可能表明岩石的物理特性,而只表示能使误差函数达到最小的值。但是用m-孔隙度变换法确定的m和n就能说明储层的物理性质(孔隙几何形状、湿润性等等)。确定出使S_(xo)(介电)和S_(xo)(阿尔奇)之间的误差达到最小的m和n值后,这些值就可用来计算侵入层的含水饱和度(S_w)。
The calculation of the water saturation (S_w) in an oil reservoir using Archie’s correlation requires the cementation index m and the saturation index n. Determining these two parameters is often difficult, especially in carbonate reservoirs. Maute et al. (1972) proposed a new method for estimating m and n. In the Core Archie Parameter Estimation (CAPE) method, the values of m and n are determined by minimizing the error between S_w obtained from the core and S_w derived from the Archie’s relation. As core data are usually not available, Asquith and Saha (1991) used the dielectric water saturation (S xo) to denote the water saturation obtained from the core. In this paper, the author uses three methods - nonlinear, linear, and m-porosity transformations to determine m and n values that minimize water saturation errors. Using the data from the Glorieta-Clearfork dolomite in Ward County, Texas, USA, the nonlinear method minimizes the error between the S_ (xo) measured by the dielectric and the S_ (xo) deduced from the Archie formula. The m and n determined by the non-linear and linear methods can not indicate the physical properties of the rock, but only represent the values that can minimize the error function. However, m and n, as determined by the m-porosity transformation, account for the reservoir’s physical properties (pore geometry, wettability, etc.). After determining the m and n values that minimize the error between S_ (xo) (dielectric) and S_ (xo) (Arx), these values can be used to calculate the water saturation (S_w) of the intruding layer.