曲线重叠法的关键因素分析及改进

曲线重叠法是油气地质评价中较常使用的一项测井评价技术,能够通过电阻率测井和声波时差测井数据计算出总有机碳含量,但是在该方法中,两个计算参数电阻率基线值和时差基线值是通过观察测井曲线图上两条测井曲线的"重叠情况"而估算出来的,带有很大的人为性和随意性,从而影响了有机碳含量计算的准确度。为了解决该问题,分析了3个绘图参数(R f、△tf、k值)对测井曲线的形状和位置的影响:当定位参数(R f、△tf)改变时,电阻率曲线的形状不变,但是在横向上产生一个总体平移量;当轴比参数(k值)改变时,电阻率曲线的形状和位置都发生变化。因此证明了轴比参数k值是关键参数,提出了使用岩心分析化验数据和测井数据通过二元线性回归模型拟合获得轴比参数k值的方法。由于避开了原公式中的基线值,新方法提高了有机碳含量计算的准确度。

Analysis and Improvement of Key Elements for Curve Overlay Method

Curve overlay method is a common used logging evaluation technique among petroleum geological evaluation.Total organic carbon content may be calculated through the data of resistivity log and acoustic time log.But these two calculated parameters,resistivity baseline value and acoustic time baseline value,estimated through observation on overlay of these two borehole logs,have man-made and arbitrary natures and it will influence the accuracy of organic carbon content calculation.In order to solve this problem,the influence of three mapping parameters（Rf,△tf,k value） on the shape and position of the borehole logs is analyzed;when the positional parameters（Rf,△tf） change,the shape of the resistivity log will not change,but total translation may occur on the lateral;when axial rate parameter（k value） changes,the shape and position of the resistivity log will both change.It proves that the axial rate parameter（k value） is the key one that can be obtained by the binary linear regression model fitting between core analysis and assay data and log data.The new method improves the accuracy of the organic carbon content calculation for no consideration of the baseline value in the original formula.