张量感应测井资料处理中若干问题的研究

在横向各向同性（TI）介质中，张量感应测井响应与地层的水平和垂直电导率σ_h和σ_v、井眼斜角α、仪器方位角φ同时有关，其资料处理和解释相当复杂，一般采用先定出φ，然后在井眼坐标系中同时反演σ_h、σ_v和α的资料处理方式.我们发现将测井响应变换到井眼坐标系时实际上无法确定其交叉分量的符号而只能确定其绝对值，这个问题尚未引起重视.本文给出了无需确定φ就可由测井响应直接计算井眼坐标系磁感应张量的公式，此方法简单，所得结果不受φ提取精度的影响.在此基础上本文给出了利用井眼坐标系的磁感应张量的交叉分量曲线提取地层纵向边界和判别相邻地层电导率高低的一种特征识别方法.本文还给出了大斜度井中TI介质的电导率视值的一种简化近似公式.

A study on some problems of tensor induction well logging data processing

In the transversely isotropic (TI) medium, the tri-axial Tensor Induction Well Logging （TIWL） responses are nonlinear functions of horizontal conductivity and vertical conductivity, σ_h and σ_v, borehole dip and azimuth angles, α and φ. The data processing of TIWL is complex multi-parameters inversion problem, usually φ is solved first, then σ_h, σ_v and α are simultaneously determined from inversion in the borehole coordinate system. However, we only make sure of the absolute value of magnetic induction tensor cross-components but not their signs when transform the data from the tool coordinate system to the borehole coordinate system. People still haven′t attached enough importance to this problem. In this paper, we first give a method to extract the information of the magnetic induction tensor in the borehole coordinate system without the knowledge of φ. On this base, we give a characteristic recognition method to extract the boundary location and the information on conductivity change of nearby bed using the magnetic induction tensor cross-component curves in the borehole coordinate system. We also give out a simplified approximate formula on the apparent conductivity of TI medium in highly deviated wells.