Research On Feasibility Test And Process Technology Of PSL3G Christmas Tree Equipment

Christmas tree equipment is an important tool for oil and gas exploration,ccording to the requirements of API 6A technology,in order to achieve the pressure of oil and gas exploitation at home and abroad,Christmas tree is developed from PSL1 to PSL4,PSL3 below the tree is only suitable for oil production,and PSL3(3G)above the tree for oil and gas production.Therefore,PSL3(3G)above the tree sealing performance directly determines whether it can be mined smoothly.This paper describes the use of Scheinin(Shainin)principle analysis method to find out the root cause of the gate and seat seal leakage caused by PSL3 G Christmas tree equipment,and through the optimization of the surface treatment process to improve the physical properties of the valve gate and valve seat,so as to solve the leakage problem of Christmas tree.Specific contents are as follows:(1)Statistical analysis of the structure of Christmas tree and the structure of each part of the failure analysis,the results showed that the main fault tree in the flat gate valve,and the fault ratio reached the total number of faults occurred in 67.25%,the leakage fault accounted for 99% of all faults,leakage fault is divided into leakage and internal leakage,leakage fault performance is quite obvious,although the internal leakage fault show no leakage fault is obvious,but Christmas tree is put into use before the first potential leakage within the exclusion.(2)Based on the PSL3 G Christmas tree strength and tightness test principle,machine pressure test use tree strength and tightness test on Christmas tree.The main purpose of the strength test is to eliminate the leakage fault,the test process is the first stage of the water pressure test and the two stage of the pressure test.The main purpose of the sealing test is to eliminate the internal leakage fault.When conduct experiment,testing all flat gate valves through the first stage of the water pressure test and the two stage of the pressure test.The test order is outside the lower main valve and the paraffin valve?inside the lower main valve and the paraffin valve?outside the main valve and the wing valve?inside the main valve and the wing valve.(3)Using the Scheinin principle(Shainin)analysis method,by listing the problem definition tree(Green Y)and the project definition tree,and pairwise comparison technology to create the failure event strategy,narrowing the scope of testing,then stage0,stage1,seage2 components of the three stages of the search process,searching out the cause of the failure of the PSL3 G Christmas tree equipment is the valve gate and valve seat.(4)Analysising the reason of leakage fault,the cause of the failure caused by valve gate and valve seat were analyzed by visual inspection,detection and process requirements,material is qualified,but through the finite element analysis showed that heat treatment caused the elastic deformation of the valve seat,resulting in leakage of fault occurrence.Through process optimization using high temperature QPQ processing technology,the depth of hardened layer of the valve gate and valve seat is greater than 40 ?m,the lowest hardness is greater than HRC50 or HK542(Knoop hardness),control the maximum deformation within the maximum limit of 20 ?m,so as to meet the requirements of the use of the valve gate and valve seat.