Electrode System Design and Response Simulation of Azimuthal Lateral Resistivity Logging While Drilling

Wireline logging in horizontal wells in high resistivity formations faces high risk,and its logging data are subject to serious lackage, which restricts accurate geosteering drilling and high-quality reservoir identification. Therefore, a novel electrode system of azimuthal lateral resistivity logging while drilling based on the non-contact coupling principle was proposed, with radial, longitudinal, and circumferential detection abilities. The effects of wellbore size, flushed zone resistivity, formation inclination, layer thickness, and surrounding rock resistivity on the detection results were investigated by using the three-dimensional finite element simulation method. The electrode system size and detection characteristics were determined, and the ambient impact calibration diagram was established. The simulation results show that the toroidal coil excitation instrument for azimuthal lateral resistivity logging while drilling has a shallow detection depth, which is generally less than that of the cable-type instrument, but it is less affected by intrusion during the drilling process. It can meet the needs of logging while drilling, has good longitudinal zone identification ability, and can define 0.5 m thin layers under the condition of high resistivity formation. With the help of quad azimuthal measurement, the position of high and low resistivity abnormal bodies can be well identified, and the formation inclination can be determined. The research results have important guiding significance for the structural parameter design of instruments for azimuthal lateral logging while drilling and exploring for high resistivity reservoirs.