An improved structure of coplanar coil system and its logging response

An improved structure of coplanar system with a narrow negative response, minimal skin effect and horns is presented, which consist of two transmitters and one receiver coil. To obtain the response of the improved coplanar system, we use an analytic method to solve Hertz potentials by applying tangential continuity in layer boundary and get the horizontal component of magnetic field intensity. Further, the models for received signals are analysed in the cylindrically and the horizontally layered formation respectively. Compared with the traditional coplanar configuration, the negative response area of the new coplanar system is significantly decreased, the responses are approximately linear and the spatial resolution is enhanced by two times. Furthermore, the improved coplanar system mechanisms are revealed for reducing skin effect and negative response through analysis of the distribution characteristics of eddy current of the transmitter coil. The results of experiments demonstrate the superiority of the proposed coplanar system.