Casing state detection methods based on the CCL signal of the tractor for horizontal wells

Magnetic locators are generally used in horizontal well logging process to obtain the CCL signal for the detection of casing couplings and then determine the working positions of logging tools. The condition under horizontal wells is so complex that the actually-measured CCL signal is easily submerged by noise due to the casing structure. It´s difficult to make accurate and direct identification, which can influence the results of logging operations. Firstly, this paper analyzes the effects of extracting features of the CCL signal from the magnetic positioning signal by using wavelet transform and Shannon wavelet entropy. Against the limitations, the multi-scale analysis method based on Tsallis wavelet singular entropy is then applied to extract features of the CCL signal from the complex signal and realizes the accurate identification of casing couplings eventually. The theoretical analysis and experimental investigation show that Tsallis wavelet singular entropy can efficiently extract features of the CCL signal and has certain recognition effect on the positioning of the perforation area.