Design of Multifunctional and Efficient Water-Based Annulus Protection Fluid for HTHP Sour Gas Wells

In order to solve the corrosion problem of production string in process acidizing for purpose production, a new water-based annular protective fluid suitable HTHP acid gas, including H2S-CO2 wells, was developed. Firstly, an appropriate deoxidizer, bactericide, and inhibitor shall be selected according gas. addition, synergism between additives is evaluated. Then, by designing additive ratio, optimal formulation determined. Finally, high-temperature autoclave used evaluate performance liquid. The results showed that it recommended use liquids prepared with clear water comes easily from nature (rivers, etc.), which consist inhibitor, CT2-19C (30,000 ppm), BN-45 bactericide (2 g/L), anhydrous sodium sulfite (3 g/L). density annulus protection liquid 1.02 g/cm3, freezing point −2.01 °C. dissolved oxygen content fluids formation controlled within 0.3 ppm. inhibition rate phase higher than 90%, P110SS steel gas–liquid lower oilfield control index (0.076 mm/y).