Abstract:Based on non-infinite three-pole profiling,the paper proposed an A-type symmetric complex foureleetrode profiling. The law and mechanism deviatingextreme point abnormal curves of A-typesymmetrie complex four-electrode profiling from boundary of oil and gas accumulation have been emphatically discussed by vast amount of modeling test in water tank and the relevant methods that can exactly define the boundary position of oil layer have been proposed. Compared with non-infinite three-pole profiling,the method can raise effieiency,deerease cost,further imrove data quality,so be favorable to improve interpretation resolution;greatly simplify the processing calculation of observing field data,so be favorable to guide field production.