八侧向测井的围岩效应研究

Study or Shoulder Bed Eflects on Laterolog 8

刘振华等．八侧向测井的围岩效应研究．测并技术，１９９５，１９（１）：４０～４５提出了成对电极二次变量代换的等位面处理方法，建立了全空间求解八侧向测井响应的物理模型并利用有限元方法求解。计算了伪几何因子曲线，研究了围岩对测井响应的影响。结果表明，围岩电阻率与地层电阻率差别愈大，围岩影响也愈明显；此外，围岩影响还与地层电阻率、地层厚度、上下围岩性质以及电极系结构有关。

A method of twice replacements of parameters used for calculating equipotential surfaces of electrode pair is suggested in this paper. The calculation model forLaterolog 8 in whole space is established and finite element method is used for thepresent model. The pseudo geometry factors are calculated and shoulder bed effectson the response of Laterolog 8 are studied. It has been shown that the larger thedifference of resistivity between shoulder bed and the formation of interest, themore obvious the shoulder bed effects. In addition, shoulder bed effect is related toformation resistivity, formation thickness, properties of shoulder beds, and thestructures of electrode system.