Study on early seal failure of CO2-injected packer based on orthogonal experimental method

Abstract

Early seal failure occurs frequently in the of CO2 injection well packer, which is mainly manifested as failure of packer rubber, which seriously affects the normal production of gas well. Aiming at the packer rubber of CO2 injection well, three factors affecting the seal failure of packer rubber were selected, namely temperature, pressure and decompression velocity and the sensitivity of each factor was analyzed by orthogonal experimental design. The results show that the mechanical properties of rubber decrease gradually with the increase of temperature, pressure, and decompression velocity. With the increase of the decompression velocity, the surface of the rubber gradually formed small bubbles, large bubbles and even bubble cracking phenomenon, rubber sealing performance parameters are significantly worse; the main cause of early packer seal failure is the gas injection well was suddenly released, and the gas that could not exude in the rubber in a short time expanded and formed bubbles or even burst under the action of the pressure difference between inside and outside. The optimal decompression velocity is obtained to keep the packer rubber seal well in the downhole corrosion environment, which provides a basis for the determination of the construction parameters of CO2 injection well.

Keywords

• Early seal failure
• Packer rubber
• Decompression velocity
• Orthogonal experimental
• CO2 injection wells