泥浆侵入地层中高分辨率感应测井响应特征的正演分析

Forward Analysis of High Definition Induction Logging Response in Mud Invasion Formation

高分辨率感应测井通过不同探测深度曲线的分离程度分析泥浆侵入状况和地层的渗透性。采用三层有侵正演模型数值模拟了阶跃和渐变侵入地层中高分辨率感应测井的响应特征。阶跃侵入地层中，侵入带电阻率与地层电阻率比值小于0．5时，6条不同探测深度曲线呈正序关系，读数从低到高；比值大于2．0时，探测深度由浅到深，曲线呈反序关系；比值为0．5～2．0范围时，浅侵入，曲线出现乱序，只有深侵入曲线才有合理的正序或反序关系。渐变侵入地层中，侵入带电阻率与地层电阻率比值为0．5～2．0范围时，过渡带变化对读数影响很小，比值大于2．0或小于0．5，过渡带对10in（非法定计量单位，1ft=12in=0．3048m，下同）和20in探测深度曲线影响最大，对90in和120in曲线影响很小。以上结论可应用于实际测井中高分辨率感应测井曲线分离的特性分析。

The separation extent of different curves of depth of investigation in array induction logging shows the conditions of mud invasion and formation permeability. The response character of HDIL in step and gradual transition invasion formation are simulated using three-layer formation model with invasion. In step invasion formation, when the ratio of invasion resistivity to formation resistivity is less than 0.5, 6 different investigation depth curves present normal order from shallow to deep investigation, the reading of the shallow investigation is less than the deep one. When the ratio is greater than 2.0, investigation curves show opposite order with the order of less than 0. 5. When the ratio is between 0. 5 and 2.0, curves are abnormal order in shallow in- vasion formation, only in deep invasion formation the curves appear reasonable order. In gradual transition formation, when the ratio is between 0.5 and 2.0, the change of transition zone has little effect on responses. When the ratio is greater than 2.0 or less then 0. 5, 10 in and 20 in curves are changed obviously, but influence on 90 in and 120 in curves is still small. These conclusions can be used to analyze the separate character of high definition induction logging curves.