Application Of Acoustic Emission Technology In Defect Detection Of Wellhead Device

Wellhead device is one of the most important equipment used in the production of oil(gas)wells.It plays an important role in the production and safety of oil(gas)wells.The two core components are wellhead Christmas tree and gate blowout preventer.During the production and service of wellhead production tree and gate blowout preventer,internal defects such as cracks,grooves or pits are prone to occur.If these defects can not be detected in time,the equipment cavity will be thinned and the strength will be reduced due to the expansion of cracks in the long-term service process,which will easily lead to the failure of the device and lead to safety accidents in oil and gas wells.Wellhead production tree and ram blowout preventer have the characteristics of complex structure,more connecting elements and thicker wall thickness.Conventional nondestructive testing methods have certain limitations in their safety detection.Acoustic emission testing technology has the characteristics of sensitivity to linear defects and insensitivity to geometrical shape of components,and its application in nondestructive testing of atmospheric oil and gas storage tanks is mature and formulated.Corresponding standards.Therefore,acoustic emission technology is selected to detect the defects of wellhead oil production tree and gate BOP,and the propagation and attenuation of acoustic emission signal in the device are studied by combining simulation and experiment.Then,the layout scheme of field detection sensors is optimized according to attenuation law,so as to realize the comprehensive detection and defect location of wellhead oil production tree and gate BOP device.In this thesis,COMSOL simulation software is used to simulate and analyze the propagation and attenuation of acoustic emission signals in four-way,clamp,gate valve chamber assembly,flange and other key devices of wellhead production tree,as well as in the shell of gate BOP.The results show that acoustic emission signals attenuate lOdB?15dB,12dB?15dB,4dB?7dB and 13dB?17dB respectively when passing through wellhead production tree four-way,clamp,cavity and flange,and 13 dB,10 dB and 16 dB respectively in horizontal,vertical and diagonal directions of main view plane of gate BOP shell.Through the field test on the attenuation law of acoustic emission signal in wellhead device,it is found that the attenuation law obtained from the field test and simulation is highly consistent,thus verifying the credibility of the simulation results.According to the attenuation law of acoustic emission signal obtained by simulation and experiment,the sensor layout scheme is designed and defect location test is carried out.The deviation between the location result and the label location is 5 mm-40 mm,and the deviation is within acceptable range.Therefore,the feasibility of the sensor layout scheme is verified.