Synthesis and Application of High Temperature Resistant Solid Acid Based on Polymer Coating

Acidizing pre-treatment is a frequently employed technique to address technical challenges in reservoir fracturing and excessive pump pressure at the wellhead during hydraulic fracturing construction. The development of high-temperature-resistant solid acid products involves the synthesis of solid acid capsule core materials, selection of optimal capsule wall materials, and preparation process. The experimental evaluation encompassed various factors such as the solubility of solid acid at different temperatures, the acid production capacity during hydrolysis, the degradation capacity of guar fracturing fluid, and the effect of acid corrosion on fracture conductivity. The study found that the solid acid demonstrated excellent stability and temperature resistance at room temperature. Even at a high temperature of 150 ℃, the acid still showed slow dissolution. When used for hydrolysis acid production with a 30% addition, the highest equivalent hydrochloric acid concentration was above 15%. The use of solid acid can enhance the degradation of the guar fracturing fluid system, leading to a shorter degradation time and reduced residue content. Additionally, solid acid can react with the reservoir rock after hydrolysis acid production, resulting in an acid-etched fracture that improves the reservoir permeability. Field applications showed that using solid acid as a pretreatment acid for reservoirs effectively improved the stress field of the reservoir and reduced the fracture pressure by 10 MPa.