Study on Failure Behavior of Gas Well Tubing Under CO2 Corrosion After Erosion

Abstract

The volcanic gas reservoir in Xushen gas field in the Northeast of China has the characteristic of low single-well production. Before gas wells are put into production, most of wells require fracturing transformation of the large sand amount and large displacement. Hence, an integrated fracturing and production string was developed. In the process of natural gas production, the integrated fracturing and production string is faced with the erosion caused by fracturing and CO2 corrosion. In order to ensure the safety of production, analysis and assessment of the dual effects of erosion and corrosion on the pipe string are required. The influence of the erosion angle, liquid velocity and sand ratio on the erosion rate of the integrated fracturing and production string was studied by using a self-made erosion experimental device and finally established the erosion rate prediction model; the samples of the tubing material after the erosion test were used in a high-temperature autoclave to carry out corrosion evaluation experiments to study the CO2 corrosion resistance of the tubing after erosion. The test results showed that severe corrosion occurred in the sample of P110 tubing after erosion, while slight corrosion occurred in the Super 13Cr tubing. On the basis of theoretical analysis results, the design and field construction of the integrated fracturing and production string are guided and ensured the safety of string in the whole life cycle.