EM Receiving Techniques of Cross-Well EM Imaging Well Logging System Research and Development

Cross-well EM Logging can measure the electrical characteristics of cross-well and regional formation, so as to obtain the information of oil, gas and water distribution between wells or regions. The difficulties existing in the research of Cross-well EM Logging Technology are analyzed to study the Cross-well EM receiving technology. By Comparing the characteristics of the two kinds of receiving magnetic antenna, the feedback high-sensitivity magnetic receiving antenna is introduced, the response of different antenna cores to frequency and the response of different winding modes to frequency are analyzed, and the parameters of the receiving antenna are obtained. The circuit and software processing in the receiving probe are combined with noise matching amplification, 1/F filtering, power frequency suppression, digital phase-locked amplification, phase-sensitive detection and other technologies to further improve the accuracy and sensitivity of the receiving probe. The receiving sensitivity is effectively improved to 10−7 nT; By research on high-precision time synchronization technology, the synchronization error is less than 100 ns, which can effectively carry out correlation acquisition to improve the extraction accuracy of EM phase. In order to further improve the receiving accuracy, the two spacing EM calibration method is used to eliminate the errors between the receiving circuit and the system. The cross-well EM receiving measurement experiments were carried out to verify that the cross-well EM receiving can measure electrical characteristics of formation across long spacing and double-layer metal casing wells.