Analysis of Response Influencing Factors and Detection Characteristicsof Hybrid Dipole Remote Detection

Accomplishing real-time detection and accurate imaging of a formation boundary is one of the current urgent and difficult points of logging while drilling (LWD). However, existing LWD technologies face problems such as overlong instruments, difficult signal synchronization, and large detection blind areas,etc. Therefore, in this paper, closed and open coils were employed as transmitter and receiver coils, respectively, and a new hybrid dipole antenna system was designed. In addition, the structure and the measurement principle of the system were explained, and the method of converting measured electric potential signals into geological signals was established. The response law and influencing factors of remote detection based on electric field signals were analyzed. Accordingly, the relationship of the real and imaginary parts of the geological signals with the coil spacing and working frequency of the hybrid dipole remote detection in typical laminated media was studied. The azimuth sensitivity of the geological signals to the formation interface, and the influencing law of resistivity and contrast on the boundary detection ability were investigated. Finally, with a single interface model, the maximum boundary detection distance of the hybrid dipole remote detection method under short coil spacing and multiple working frequencies was determined. The research results can provide a theoretical basis for the development of logging instruments with hybrid dipole remote detection.