低阻油气层评价方法

在广泛收集低阻油气层资料的基础上对低阻成因进行了划分,进一步明确了低阻油气层的概念与分类.低阻成因分为内因和外因,内因是指油气层本身岩性物性变化引起的,外因是指非地层因素变化引起的,如地层水变化.针对低阻油气层的评价难点,首次提出用测井相的概念进行低阻油气层的定性识别,见到了明显成效.提出并完善了双孔隙水模型[1],应用多种矿化度盐水的岩电测量,通过线性拟合及理论推导解决了模型参数(如饱和度指数等)的确定问题,从而比较容易地直接用该模型进行饱和度定量计算.应用该模型计算得到的油气层含水饱和度与束缚水饱和度误差一般不超过5%.这带有普遍性的方法在数油田的实际应用证明是成功的.

LOW CONTRAST RESISTIVITY RES ERVOIR EVALUATION METHOD

The factors leading to low contrast resistivity have been classified into inner and outer causese by analysis of some oil fields' information.The inner causes are the variations of lithology,porosity and permeability,and the outer cause is the variation of non-formation factors,such as the changing of formationm water salinity.The concept of log facies is first used for identifying low contrast resistivity reservoir,and shows satisfactory results.A Dual Porosity Water Model has been put forward and perfected by using core electric measurements with multi-salinity waters for the determination of model parameters,which are obtained by linear regression and theoretical computation.The result of an example shows that the water saturation of low contrast resistivity oil/gas formation is very close to its irreduciable water saturation,and the errors are usually no more than 5%.Furthermore,these methods aimed at common uses have been confirmed effective in a number of oil fields.