三分量阵列感应共面线圈系在均匀地层中的响应特性分析

Analysis of Response Characteristics of Coplanar Coil System of Tri-axial Array Induction Logging Tool in Homogeneous Formation

采用类似于共轴三线圈系的方法推导了共面三线圈系视电导率的解析解,对比共面线圈系与共轴线圈系Born几何因子响应特性,分析工作频率、主接收线圈位置和比例系数α对共面线圈系响应特性的影响。结果表明:仪器的工作频率越高,距发射线圈的距离越远,趋肤效应越严重;比例系数α越大,井眼影响和目的层影响的负贡献越大,但α无论多小,负的响应影响依然存在,这是目前三分量感应共面线圈系的固有缺陷。通过分析目前三分量共面线圈系的特点及其存在的问题,为今后共面线圈系的设计优化提供参考。

An analytical solution of the apparent conductivity of three coplanar coil system is derived using the method similar to three coaxial coil system,the Born geometric factor response characteristic of the coplanar coil system is compared with that of coaxial coil system,and the influences of operating frequency of the coil system,the position of main receiving coil and coefficient α on the response characteristics of the coplanar coil system are analyzed. The results show that the higher the operating frequency and the farther the distance from the transmitter coil,the more serious the skin effect. The greater the coefficient,the greater the negative contribution of the borehole effect and the target layer,but their negative contribution still exists no matter how small is,which is an inherent defect of the coplanar coil system of tri-axial induction logging at present. The analysis of the characteristics and existing problems of the coplanar coil system of tri-axial array induction logging tool will provide a very good reference for the design and optimization of the coplanar coil system in the future.