| Casing damage will directly affect the production and development of oil and gas wells.Through casing damage detection technology can get a more comprehensive casing technology status,help to carry out casing damage repair and prevention work,which has an important role in oil field development and stable production.In this paper,through the analysis of electromagnetic and mechanical methods in the casing damage detection engineering application of the merits and demerits and instrument working principle,the detection method of two combinations is proposed.The purpose is to obtain a large number of casing damage information.The overall design scheme of the system and the data fusion and uploading mechanism after the combination of the two instruments are studied,and the paper focuses on the detection system of the multi-arm caliper casing.The detection performance of the caliper probe is studied,and the relevant circuit and the corresponding software of are developed.The circuit modules of the downhole system are debugged,and the caliper PC software system is researched and designed.Based on the analysis of the characteristics of casing detection signals,a ground interpretation method based on wavelet analysis is put forward.Firstly,The background and significance of the subject,as well as domestic and foreign development are introduced.Then,the casing damage detection theory and the function and performance of the system are analyzed,and the method of combining the electromagnetic flaw detector and the caliper is proposed.The underground data fusion circuit and communication protocol based on RS485 bus are designed,and the data transmission of downhole to ground is realized by the way of capacitance coupling.The differential transformer displacement sensor of the core component of the caliper is researched and designed.With ADUC832 as the core,the probe excitation circuit,signal reception conditioning circuit as well as the A/D acquisition circuit are designed.The temperature measurement circuit is designed by balanced bridge principle.The program design of the hardware circuit of the downhole system is completed by using KEIL software.To achieve the display and image of the collected data,the software of the multi arm caliper is programmed by LABVIEW,so we can see the specific casing damage situation.Based on the study of the characteristics of the combined casing flaw detection signal,the point mutation detection signal based on wavelet multiresolution analysis is proposed,and the algorithm of the mutation point detection is studied.The Wavelet analysis is applied to the measurement data to realize the interpretation of the logging signal.The two types of signals containing the mutation point are used to simulate the flaw detection signal,and then they are imported in GUI MATLAB.The simulation of wavelet multi-resolution analysis is conducted,the results show that the wavelet analysis is effective for the detection of the mutation point.On the basis of the theoretical research and the development of the underground system,the debugging of each circuit module is carried out finally,and the feasibility of the design is verified.The theoretical and experimental results presented in this paper can provide important technical reference for the development of caliper and electromagnetic combined casing system. |
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