Study on Causes and Prevention Measures of Casing Damage in CO2 Test Area of X Oilfield

In Since the CO2 test in X field, 28 Wells have been found with casing damage, more than 93% of them are gas injection wells. Gas injection well with casing damage, easy to cause oil and gas up to the surface. There are safety and environmental protection risks, and it also affects the integrity of well pattern and development effect. Gas injection well overhaul construction cost is high, a single well up to 2 million yuan. Therefore, the causes of casing damage and prevention measures are studied. By means of nondestructive testing, SEM + EDS and XRD analysis of corrosion products, the main cause of casing damage was determined by H2S corrosion. The basic conditions of H2S corrosion are determined by establishing the distribution model of pressure and temperature in gas injection wells. According to the results of the study on the causes and rules of casing damage, the template of casing damage risk assessment was formed, and the prevention measures of casing damage were formulated. From the field application effect, the proportion of casing damage was reduced from the initial 53.6% to 4.5%, greatly prolonging the service life of gas injection wells, and providing an important technical guarantee for the smooth development of the subsequent CO2 test in X oilfield.