Calibration method of azimuth electromagnetic boundary detection logging while drilling based on air–seawater double-layer dielectric as reflection interface

Abstract

Abstract An azimuth electromagnetic propagation logging while drilling tool provides the electrical parameters around a well in the intelligent drilling guidance system. It is a key link in intelligent guidance technology. As the stratum directivity parameter, the azimuth signal is associated with the compensation measurement of the resistivity instrument, which guides the drilling. However, it must be calibrated to have physical significance. The traditional method uses a water tank for calibration. However, this method is affected by the edge effect, which greatly weakens the azimuth signal. The model is complex and difficult to recover, which seriously suppresses the calibration results and causes errors in the azimuth signal. To eliminate the edge effect and simplify the model to improve the signal quality, an instrument calibration method based on sea level as the reflection interface is proposed in this paper. The air–seawater structure can simplify the calculation model, eliminate the edge effect and improve the signal strength. According to 1D air–seawater model simulation and 3D water tank model calculation, the feasibility of the simplified model is analyzed. According to the azimuth signal characteristics of the simplified model, an azimuth signal correction process that is more suitable for azimuth electromagnetic propagation logging while drilling is proposed. The measured data show that the air–seawater model improves the signal-to-noise ratio of the azimuth signal, verifies the detection ability of the azimuth antenna and provides technical support for oil and gas development in complex reservoirs.