CO2 Corrosion of Downhole Sand Control Screen: Experiments, Model, and Application

Under simulated conditions typical of a high-temperature, high-pressure (HTHP) oil and gas reservoir in the South China Sea, dynamic corrosion evaluation experiments were performed on a three-layer screen structure and three types of sand retaining media. The results showed significant variations in corrosion morphology and rates among different screen components and materials. Corrosion products on the base pipe accumulated as cubic crystals, while the protective shroud showed surface needle-like corrosion products. Sand retaining media exhibited "coiled wire" corrosion products with cubic accumulations along seam edges. The 316L media showed a high corrosion risk, especially at temperatures between 140-150 degrees C. As CO2 partial pressure increased, corrosion rates generally rose. A new predictive method was developed to assess and compare the corrosion resistance and life of screens, achieving a compliance rate of over 90%. This method supports evaluating the corrosion life of screens in HTHP environments. For a typical well in the South China Sea gas field with 4% CO2, there is a high risk of screen corrosion. The screen media was identified as a failure site with a minimum corrosion life of about 5 years, while the protective shroud's life was estimated at 11-12 years.