三分量感应测井的正反演理论及性能研究

Study on forward modeling and inversion theory and properties of three-component induction logging system

常规感应测井仪器只有Z方向的线圈系,只能测量水平方向的平均电阻率。三分量感应测井系统分别在X和Y及Z方向布设了3组互相垂直的发射-接收线圈对,可直接测量地层的水平电阻率和垂直电阻率;在XZ平面和XY平面布设了2个交叉线圈,通过测量2个交叉分量可以得到地层的倾角和方位角,为储层评价提供更准确的信息。设计了三分量感应测井系统线圈系的布局结构、排列方法和聚焦方式。通过对线圈系匝数和距离的选取、几何因子的计算以及各向异性介质的正、反演研究,使三分量感应测井系统线圈系的水平探测深度和纵向分辨率得到了提高,能很好地反映出地层的真实特征。

Conventional induction logging devices only have z-orientation coil and detect average resistivity in horizon.However,three-component induction logging system sets three mutually orthogonal transmitter-receiver coil pairs in X,Y and Z directions respectively, and measure horizontal and vertical resistivity directly.The system also sets two cross coils in XZ and XY plane,and can obtain dip and azimuth of formation by measuring the two cross components. The above measurements provide more accurate information for reservoir evaluation.Therefore,we developed the configuration, arrangement and focusing means of coil array for the three component induction logging system.By appropriately selecting the turns and distance of coil system,computing geometric factors, and studying forward modeling and inversion of anisotropy medium, the horizontal detecting depth and longitudinal resolution are improved,which can well reflect the actual features of formations.