Analysis of Signal Response and Detection Performance of Azimuth Transient Electromagnetic Logging While Drilling

The frequency domain ultra-deep electromagnetic logging-whiled-rilling (LWD) tools have been widely used in steering and reservoir mapping. However, to increase the detection depth, these tools need to increase the length and reduce the signal frequency, which poses challenges to the inversion of the thin layer information. In contrast, the azimuth transient electromagnetic LWD instruments can provide geological information by the short transmit-receive distance, which is of great significance for simplifying instrument structure and realizing active geosteering. In this paper, the instrument is composed of a tilted transmitting coil and two co-located and orthogonal receiving coils. The transmit-receive distance of the instrument is 1m. The instrument can compute the time-domain geosignal by decoupling the received response to obtain a multi-component response during the rotation while drilling. The boundary detection capability is analyzed by setting different formation models and minimum signal detection strengths, which is conducive to improving the application potential of transient electromagnetic logging in active geosteering.