Simulation And Application Of CO ₂ For Corrosion Of Natural Gas Well

CO2has long been considered an important reason for corrosion. With the exploitation of oil and gas fields, CO2has been widely used for tertiary recovery. The CO2corrosion, the difficult technical problem, is attracting more attention in the world. Therefore, the corrosion rate model for prediction, which based on CO2corrosion mechanism and its effect factors, is built for the efficient exploitation of oil and gas development and production.Effects of temperature, CO2pressure, flow rate, cl-concentration and HCO3-concentration on CO2corrosion rate of nine low alloy steel were studied based on the experimental data, As well as the volume of Cr. The results show that TP80NC-5Cr pipe has the best performance of corrosion resistance for It is high volume of Cr (about5%). In addition, the prediction model about steel flow rate of nine kinds of pipes and the chloride ion concentration effecting on CO2uniform corrosion rate is constructed by least square method.The distribution of the wellbore CO2corrosion rate needs to be studied during the process of gas production. The mathematic model, calculating pressure, temperature, flow rate and density of gas in the wellbore is built and is coupled with DeWaard&Milliams CO2corrosion rate prediction model to establish the mathematic model predicting CO2corrosion rate in different well depth. According to this mathematic model, a computer program is compiled in order to predict pressure, temperature, flow rate, density and CO2corrosion rate in the wellbore under different conditions of natural gas well. Meanwhile the mathematic model is corrected by the reliable data acquired in corrosion test which is done under conditions of indoor simulation. These results are contrast with the scene monitoring to get the model simulations which is actually used for CO2corrosion of the gas wellbore.Based on the mechanism and the model simulations about CO2corrosion of the gas wellbore, this thesis discusses how to protect the gas wellbore from corrosion. The result of the study proves the model simulation is valuable and practical.