Research On Laser Telemetry Of Associated Gas Release And Leakage In Oil Wells Under Non Cooperative Targets

With the rapid development of China’s social and economic development,the demand for energy continues to expand.As the lifeline of national industrial development,reasonable exploitation and utilization of oil is particularly important.However,during the oil extraction process,due to corrosion and perforation of wellhead Christmas tree valves,valve failure,aging and other reasons,associated gas leakage and escape occur,leading to frequent safety accidents.In the early stages of a leak,if precise and effective detection cannot be carried out,it can lead to energy waste,major explosion accidents,harmful physical health of oil field workers,and environmental pollution.Therefore,conducting accurate and effective detection of associated gas leakage and dissipation is of great significance to the oil extraction industry.Based on fluid mechanics and semiconductor laser absorption spectroscopy(TDLAS),taking the leakage and dissipation of associated gas as the research object,the characteristics of associated gas leakage and dissipation were explored,providing a basis for the scientific and reasonable layout of the laser telemetry optical system for associated gas leakage and dissipation.The interference analysis of absorption spectral line components based on TDLAS technology was conducted,a correction and compensation method for the influence of temperature on the second harmonic has been proposed to reduce the error of the laser telemetry system.An analysis of the optical transmission characteristics of the laser telemetry optical system has been carried out to improve the optical signal reception efficiency of the optical system.The main research content of this article is as follows:(1)Based on the FLUENT software,the variation law of methane leakage concentration distribution with time,which is the main component of associated gas,is analyzed,and the influence of leakage speed and ambient wind speed on methane leakage concentration distribution is analyzed,designed a scientifically reasonable and targeted layout plan for the laser telemetry optical system;(2)Analyzed the interference factors of the absorption spectral line components of associated gas,determined the main component of methane absorption spectral line of associated gas,clarified the influence of temperature on second harmonic,and studied the correction and compensation method of temperature on second harmonic;(3)Based on the TRACEPRO software,the optical transmission characteristics of the laser telemetry optical system under non cooperative targets were analyzed,and the size and structure of the laser telemetry optical system components were optimized,thereby improving the optical reception efficiency of the optical system.Five sets of methane laser telemetry tests were carried out,including calibration experiments,accuracy testing experiments,stability testing experiments,laser scanning experiments,and experiments on the impact of different reflection target surfaces on laser detection.The calibration experiment had a fitting degree of 0.996,indicating good fitting performance;The accuracy testing experiment shows that the relative error of methane laser telemetry is less than 0.115;The stability test experiment shows that the RMSE of the system is 55.09ppm·m,and the IS is 76%;The scanning test results show that the system measures the methane concentration in the corresponding cylinder at the corresponding angle of the methane cylinder position,which has high reliability;The methane laser telemetry results under different reflection targets are similar,indicating strong anti-interference ability of the system.