双侧向测井曲线形状的影响因素研究

为研究井眼、层厚和侵入带对双侧向测井曲线形状的影响，利用正演模拟技术分别对各种常见情况计算了双侧向曲线。结果显示，井径增大使曲线变化趋缓，且幅度降低；泥浆电阻率与地层电阻率反差的增加则使曲线棱角更加分明；层厚在1m以下时高侵层无双尖峰现象，2m以上厚层曲线形态变化不大，低侵层厚度〉4m时，曲线在地层中部开始出现平顶；侵入带厚度较小时，曲线的侵入特征更明显，厚度大时趋于无侵入高阻层的形态；侵入带与地层和围岩的电阻率对比决定曲线的形状和幅度。

Investigation on influence factors of laterolog curve form

In order to investigate the influences of caliper, formation thickness and invaded zone on the form ofdual-laterolog, forward modeling technique was applied to calculate the dual-laterologs for different cases. The result shows that the resistivity logs become smoother and lower as the borehole diameter increases, the increase of the contrast between mud resistivity and formation resistivity induce the logs to be more pointed. When the formation thickness is less than 1 m, the two-peaks on the logs for resistive invasion vanished, and for thickness between 1 m and 4 m the form of logs does not vary significantly. If the formation thickness was greater than 4 m, a platform appears on the logs would be in the middle of the formation. The thinner the invaded zone is, the more obvious the invasion feature on the laterologs is. For thick invaded zone the form of logs tends to be that of an uninvaded resistive formation. The form and amplitude of logs depend on the resistivity contrast between the invaded zone and the uninvaded formation and adjacent layers.