多传播电阻率测井的探测能力与资料处理方法

Detective ability and data processing method of the MPR logging

为了研究多传播电阻率(MPR)测井对砂泥岩薄互层和低电阻率环带的识别评价能力及其资料处理方法,利用薄互层组和低电阻率环带地层模型研究了MPR的探测性能及其资料处理方法。MPR可提供4条相位差和4条幅度比测井曲线,但某些探头的径向积分响应曲线存在相互重叠和交叉,说明MPR资料含有较多重复信息。幅度比曲线对地层电阻率的探测灵敏度比相位差曲线的探测灵敏度低得多。因此,从MPR的8条测井曲线中选出3条相位差和2条幅度比曲线作为资料处理的主要依据,利用所选出的5条测井曲线可直观识别出薄互层和低电阻率环带,但一般还不能由视电阻率曲线直接获得地层电阻率的真值。应用改进的正则化阻尼型高斯-牛顿优化算法,实现了MPR模拟资料的二维反演,对薄互层和低电阻率环带地层模型得到了较好的反演结果,可显著提高MPR资料的解释精度。

The detective ability and data processing method of the MPR （multiple propagation resistivity） logging were studied by using the thinly laminated sequence and the low resistivity annulus formation models. The MPR tool of Baker- Hughes INTEQ provided four phase difference curves and four amplitude ratio curves. The radial integral response curves of some probes of MPR crossed each other, suggesting that there was much repeated information among MPR data. The sensitivity of amplitude ratio curve to formation resistivity was much lower than that of phase difference curve. In this paper, three phase difference curves and two amplitude ratio curves are selected out from the eight logging curves for the MPR data processing. Based on the selected five curves, the thin interbeds and the low resistivity annulus can be identified through the senses. However, the true value of formation resistivity cannot be obtained from these apparent resistivity curves. The two-dimension inversion of MPR synthetic data are carried out by using an improved damping regularized Gauss-Newton optimization algorithm. Satisfying inversion results are obtained for thin interbeds and low resistivity annulus formation models.