Corrosion And Protection Of The Core Parts Of High-CO₂-CutOil Produced Well

CO₂-EOR is a technology which can not only solve the problem of CO₂ storage but also improve the recovery rate of oil field.But the CO₂-EOR oilfield,CO₂ will seep into the recovery well sooner or later,the cut of CO₂ of the product fluid in oil wells will raise.And CO₂ will cause corrosion of underground parts of wells.Study on the CO₂ corrosion of underground parts and find out the countermeasures is very important to the success of CO₂-EOR.There are two ways to solve the corrosion problem.made the underground parts from corrosion resistant materials,or predict the service life of underground parts and take measures to reduce the loss.In this paper,simulate the actual production situation,apply P110,N80,J55,Cr 13 type steel used in oil field production,study the CO₂ corrosion behaviors under different temperature and different C02 partial pressure.Under the condition of 20MPa pressure and 0.1 MPaC02 partial pressure and 80? temperature,the C02 corrosion rate deCrease with the time,and tends to stable after 2 days;under the condition of 20MPa pressure and 0.1 MPaC02 partial pressure,the CO₂ corrosion rate in Crease with the temperature and peak at the 80?,than the rate turns to deCrease;under the condition of 20MPa pressure and 60? temperature,the CO₂ corrosion rate inCrease with the CO₂ partial pressure,and tends to stable after the 2MPa of CO₂ partial pressure;under those different conditions,the N80 type steel holds the maximum rate of CO₂ corrosion,J55 and P110 types hold the medium position,Cr 13 type hold the minimum.According to the experimental data,by using Cr 13 steel downhole components,like oil pump made fromCrl3,can slow down the corrosion rate.But for the components have blown in or difficult to made by Cr 13,can predict the service life and take measures in head of the accident.For the disadvantagesof poor universality of current prediction models,the DWM model should be fixed by the experiment data to make it more fit to the actual facts.By combine the DWM model and NORSOK M506 model with ACME B31G standard and force analysis method of rod string,gives the service life predict method.By combine it with the temperature and pressure of well,make a program to predict the service life of tube and rod string of different depth.Considerthat the first position become invalid of rod string is located at the wellhead,and of the tube is at the bottom.