Research On Detection Method Of Transient Electromagnetic And Multi-arm Casing Combined Multi-layer Pipe String

With the deepening of oil and gas development work,most China’s oil fields gradually enter the middle and later stages of exploration and development,and casing damage is becoming more and more complex.High precision casing damage detection has become one of the key technologies for improving oil and gas recovery.Based on pulse eddy current testing technology,this paper focuses on the multi-layer string damage detection method combining transient electromagnetic flaw detector and multi-arm caliper.In this paper,the necessity of the combination of multi-arm caliper and transient electromagnetic detector and the overall design feasibility of the combined logging tool are studied,and the theoretical basis of the multi-arm caliper and transient electromagnetic detector is introduced.The advantages and disadvantages are compared and analyzed.According to the principle of transient electromagnetic and multi-arm caliper,the key technologies of combined logging tools are studied,including structure design,power supply system,hardware circuit and downhole software system and so on.On this basis,the combined logging tool is optimized,and the multi-arm caliper differential mutual inductance displacement sensor is designed and manufactured.The control method of the multi-arm caliper downhole motor is improved,and driving circuit of the underground H-bridge motor is optimized.It makes the downhole circuit system of the instrument more stable.In addition,in view of the large amount of downhole data of the combined logging tool,the downhole data processing circuit is optimized to improve the logging efficiency of the instrument.Finally,a series of indoor scale experiments and outdoor simulation experiments are carried out on the combined logging tool,and the damage of the casing is calibrated to verify the feasibility of the combined logging tool.The experimental results show that the combined logging tool makes the joint interpretation of logging data easier.The same logging result replaces the traditional two logging,which not only improves the accuracy of data interpretation,but also shortens the logging time.