Study On The Data Processing Method Of Through-casing Resistivity Logging

Through-casing resistivity logging proves to be of increasingly signiifcant engineeringvalue in many ways, such as monitoring dynamic reservoir and evaluating the remaining oil.Its development potential is tremendous. Combined with weak signal detecting technology, thefatrher study on data processing method in through-casing resistivity logging is carired out andthe method of logging data processing, basing on the logging signals featured with0.1Hz frequency, is designed in this paper.To begin with, this paper describes the principle of the through-casing resistivity logging,analyzes the impact of the frequency of logging signals on logging, and set the frequency oflogging signals as0.1?. Secondly, basing on the characteristic that the leakage current ofthe logging method with single source electrode is only nanovolt, the detecting method ofextremely weak signals under strong noise is analyzed and the design of an appropirate dataprocessing method is described in detail. The data processing method including cumulativeaverage and correlation detection algoirthm is tested in simulation expeirment to be eiffcient insuppressing noise and improving signal to noise ratio, and achieves extracting weak signalsfrom strong noise accurately. Finally, the entire algoirthm is wirtten as汪computer program inVisual DSP++3,0,and the data processing method is transplanted to ADSP2189M with theportability of the programming environment.The results show that: the data processing method achieves high detecting accuracy at thelowest signal to noise ratio of working threshold of-lOdB, With the processing method,thedata detection system achieves accurate detecting the amplitude of signals in low signal tonoise ratio,and the resolution could reach nanovolt. The nonlinear error of results of formationresistivity measuring in the system is less than土3%...