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用电阻率和孔隙度测井方法推导出一个有效介质理论计算饱和度的方程(Hanai—Bruggeman方程),这个饱和度方程具有分散状粘土和层状泥质砂岩模型两大功能。饱和度公式中有五个参数变量,即总孔隙度、真电阻率、地层水电阻率、胶结指数和骨架(颗粒)电阻率。 在分散状粘土模型中,总孔隙度,地层真电阻率和地层水电阻率用标准的测井分析方法计算,胶结指数和骨架电阻率是通过岩石分析得来的。饱和度方程中的五个参数或变量用于计算总的含水饱和度,亦用于进一步计算有效含水饱和度。中间变量用于计算粘土体积、有效孔隙度、胶结指数和骨架电阻率。 在层状泥质模型中,泥质部分当作夹层处理,从岩石体积中扣除,这样其地层电阻率就可以直接输入砂岩方程中计算饱和度。 泥质砂岩模型的计算是精确和稳定的,它已被发表的有关测井资料,包括低电阻率和低差异的例子所证实。饱和度可以用标准的测井组合确定,计算参数的方法非常直观、简明,且计算顺序是灵活可变的,允许有异常的情况,比如存在非粘土的微孔隙。
A resistivity and porosity logging method is used to derive an equation (Hanai-Bruggeman equation) for calculating the saturation of an effective medium. This saturation equation has two major functions of a dispersed clay and a layered muddy sandstone model. There are five parameter variables in the saturation equation, total porosity, true resistivity, formation water resistivity, cementation index, and framework (particle) resistivity. In the dispersed clay model, total porosity, true resistivity of the formation, and formation water resistivity are calculated using standard log analysis methods, and the cementation index and framework resistivity are derived from rock analysis. Five parameters or variables in the saturation equation are used to calculate the total water saturation and are used to further calculate the effective water saturation. The intermediate variables are used to calculate the clay volume, effective porosity, cementing index and framework resistivity. In the layered mud model, the muddy part is treated as a mezzanine and subtracted from the rock volume, so that the resistivity of the formation can be directly input into the sandstone equation to calculate the saturation. The calculation of the shaly sandstone model is accurate and stable and it has been published as evidenced by the well logging data, including the examples of low resistivity and low variability. Saturation can be determined using standard logging combinations. The method of calculating parameters is straightforward and concise, and the order of calculation is flexible and allows for unusual conditions, such as the presence of non-clay micropores.