常规测井特征比值法在大牛地气田产能评价研究中的应用

Application of Logging-ratio Characteristic Parameters to Productivity Evaluation in Daniudi Gas Field in Northern Ordos Basin

从鄂尔多斯盆地北部大牛地气田上古生界致密砂岩天然气储层的地质和岩性特征出发,在储层参数精细解释基础上,完成了一项储层产能分析与评价方法研究。首先把常规测井资料分类处理成几组本地区的测井特征参数比值,包括:岩性测井比值(自然伽马相对比、井径比)、电性测井比值(自然电位相对比、深浅电阻率比)、物性测井比值(时差比、密度比);把这些比值按地区经验加权合成为储气层产能综合比值K;把K和气层厚度H的乘积KH(取名为测井储能特征指数)与气层无阻流量测试数据相拟合,得出相应的经验回归关系。在评价气层时,用K值划分产能级别,用KH值预测产能。实测结果表明该方法效果明显,已在大牛地气田的新井储层产能评价和老井挖潜工作中推广应用。

Started from the geological and lithological characteristics of the tight sandstone reservoir of Upper Palaeozoic in northern Ordos Basin, Daniudi Gas Field, and based on fine interpretation of reservoir parameters, a research on method for analyzing and evaluating potential productivity of gas reservoir has been completed. This method firstly distills some classified groups of local logging-ratios as characteristic parameters of the reservoir, including lithological parameters （ratio of relative Gamma Ray, ratio of caliper）; resistivity parameters （ratio of relative spontaneous potential, ratio of deep to shallow resistivity）; porosity parameters （ratio of acoustic slowness, ratio of density）; then integrates these parameters weighted by local empirical values to form a integrated ratio of potential pro- ductivity of the gas reservoir （K） ; fits the product KH of K and the layer thickness H of the reservoir, named as logging characteristic index for the potential of the reservoir （KH）, to data measured in non-resistance flux test of the gas reservoir, and gets corresponding empirical regression relation. Finally, in evaluation of gas reservoir, the K is used to grade the gas reservoir as its criterion, and the KH to predict potential productivity of the reservoir. Good effects of the method have been shown by test results, and its applications have been extended to reservoir productivity evaluation of new-drilled wells and re-analysis of old-drilled wells in Daniudi gas field.