Simulation to Determine Depth of Detection and Response Characteristics while Drilling of an Ultra-Deep Electromagnetic Wave Instrument

Studying the boundary detection depth while drilling for different antenna combinations is the primary objective of developing ultra-deep electromagnetic wave instruments. The numerical simulation method has been used to study the boundary detection depth and response characteristics of three kinds of receiving antennas: axial antenna, horizontal antenna and tilted antenna. The simulation analysis suggested that the detection depth while drilling for the ultra-deep electromagnetic wave instrument was related to the antenna spacing, operating frequency and the formation resistivity contras. Further, it became clear that different electromagnetic field components had different response characteristics to the formation interface, and the axial resistivity measurement of ultra-deep detector was more likely to be affected by adjacent layers than the conventional electromagnetic waves. When the horizontal receiving antenna was used, the smaller the antenna spacing and the higher the operating frequency, the larger the potential signal amplitude of directional electromotive force. Then, when the tilted receiving antenna was used, the larger the antenna spacing and the higher the operating frequency, the larger the potential relative directional signal amplitude. While using the ultra-deep electromagnetic wave instrument while drilling, the antenna spacing should be small when the horizontal receiving antenna is used, and the distance should be large when the tilted receiving antenna is used. Further, the combination of multiple frequencies and antenna spacing can increase the detection depth while drilling and therefore, the adaptability to the formation resistivity of ultra-deep electromagnetic wave instrument. By reducing the operating frequency and increasing the antenna spacing, the detection depth of ultra-deep electromagnetic wave instrument while drilling can reach 20−30 m. The study showed that the detection depth could bridge the gap between seismic and well logging, and make it possible to describe the oil reservoir while drilling.