Study On Corrosion Mechanism And Protection Technology Of Tri Joint Crude Oil Gathering Pipeline

Because of the complicated topograpHic fluctuations,the tower triple crude oil gathering and transportation pipeline has a pHenomenon of oil-water layer flow in the pipeline,leading to serious water deposition in the low-lying areas of the terrain.At the same time,the produced material contains large amounts of CO2 and Cl-and exhibits a low pH value.As a result,the pipeline is seriously corroded.When the main influencing factors of inner corrosion temperature,CO2 partial pressure,flow rate,Cl-concentration and other internal corrosion factors change,the content of corrosive substances such as CO2 and Cl-in oil water will be different from the corrosion product film that occurs on the surface of metal substrate.The film formation has an effect,and it also affects the pitting process that occurs on the surface of the metal substrate.In response to these problems,this paper takes Tasang crude oil gathering and transmission pipeline as the research object,adopts a combination of theoretical research and indoor corrosion experimental research,studies the internal corrosion mechanism and corrosion rate of the tower triple crude oil gathering and transmission pipeline,and establishes a tower.The prediction model of the internal corrosion rate of the triple crude oil gathering pipeline was proposed and the corrosion protection measures for the tower triple crude oil gathering pipeline were proposed.The specific research content is as follows:(1)In order to obtain the basic conditions of pipelines such as operating parameters,internal corrosive media,pipeline materials,corrosive perforation,and corrosion causes of the triple-tower crude oil gathering and transmission pipeline,on-site sampling and pipeline condition investigations were conducted;The ionic composition,corrosion products,corrosion morpHology,and chemical composition of the pipeline material of the corrosive medium in the crude oil gathering and transmission pipeline determine the corrosion of the tower triple crude oil gathering and transportation pipeline as a result of the joint action of CO2 and Cl-;analysis may affect the The factors of corrosion behavior mainly include:CO2 partial pressure,temperature,Cl-concentration,and flow rate.(2)Based on the conditions of the internal corrosion of the Tusan crude oil gathering pipeline and the working conditions of the pipeline,combined with the high-temperature and high-pressure reactors and electrochemical workstations,the corrosion experiments and electrochemical corrosion experiments of the indoor high-temperature and high-pressure reactors were carried out.The uniform corrosion rates of the tower triple crude oil gathering and transportation pipeline ranged from 0.72 mm/a to 3.44 mm/a,and the pitting corrosion rate ranged from 2.35 mm/a to 13.05 mm/a.The internal corrosion of the tower triple crude oil gathering and transmission pipeline was studied.Mechanism discovery:The internal corrosion of the tower triple crude oil gathering and transmission pipeline is characterized by uniform corrosion,supplemented by pitting corrosion;temperature,CO2 partial pressure,and temperature increase all lead to an increase in the uniform corrosion rate and pitting corrosion rate.When Cl-concentration is lower than 69,600 mg/L,the increase of Cl-concentration will increase the uniform corrosion rate.When Cl-concentration is greater than 69600 mg/L,the increase of Cl-concentration will reduce the uniform corrosion rate;Cl-concentration Increasing it will increase the pitting rate.(3)The corrosion rate obtained from the experimental test is supported.Based on the experimental results and the corrosive media characteristics of the triplet crude oil gathering pipeline,the Norsok corrosion prediction model was revised,and the temperature function calculation model and pH were revised.Value calculation model,viscosity-temperature curve model and wall roughness values were taken,and the influence coefficient of Cl-concentration was innovatively added.A uniform corrosion rate prediction model suitable for tower triple crude oil gathering and transmission pipelines was established.According to the test results of pitting corrosion rate,a numerical regression analysis method was used to establish a prediction model for the pitting corrosion rate of the tower triple crude oil gathering and transmission pipeline.(4)In view of the internal corrosion problem of the crude oil gathering and transmission pipeline of the Tri-Spane Group,this article selected the COW2013 corrosion inhibitor as a corrosion protection measure to reduce the internal corrosion rate of the triplet crude oil gathering pipeline and ensure the safe operation of the pipeline.The safe and stable operation of the gathering and transportation pipeline provided certain suggestions.It also provided ideas and lessons for internal corrosion research and internal corrosion protection of crude oil gathering pipelines in Tarim Oilfield.