羟基磷灰石耐高温抗CO2腐蚀水泥浆

高温气井固井过程中，必须对水泥浆进行防腐处理。受腐蚀仪器与抗高温聚合物防腐剂的限制，高温区域水泥石相关防腐报道较少。以实验室自制的聚合物乳液为聚合物防腐剂，研选羟基磷灰石为无机防腐填料，构建了一套适用于高温气井的羟基磷灰石耐高温抗CO₂腐蚀水泥浆体系，并评价其常规性能、抗窜性能与防腐性能。结果表明水泥浆流变性良好、抗窜能力强，90 d内水泥石腐蚀深度低于0.5 mm。水泥石XRD与SEM分析表明，高温区域内凝胶性物质与氢氧化钙基本消失，腐蚀反应比较单一，主要是硬硅钙石与CO₂相发生了反应。LKseal聚合物防腐剂通过成膜作用减少CO₂侵蚀水泥石，羟基磷灰石通过吸收CO₂并生成叠片状碳酸羟基磷灰石修补腐蚀后孔洞，进一步提高羟基磷灰石水泥石抗腐蚀能力。 

A High Temperature CO2 Resistant Hydroxyapatite Cement Slurry

Cement slurries used in high temperature gas wells must have corrosion resistance. Reports on corrosion resistance of set cement in high temperature wells are rarely seen because of the corrosion of the cement slurries to the testing equipment and the lack of high temperature polymer corrosion inhibitors. A high temperature CO₂ resistant hydroxyapatite cement slurry was formulated with the hydroxyapatite as inorganic corrosion inhibitor and a self-made polymer emulsion as the polymer corrosion inhibitor. Laboratory evaluation results have sown that the cement slurry has good rheology and anti-channeling performance. Depth of corrosion on the set cement in 90 d is less than 0.5 mm. XRD and SEM analyses of the set cement have demonstrated that the gelatinous substance and calcium hydroxide almost disappeared in the high temperature area. The only corrosion reaction was the reaction between the xonotlite and CO₂. LKseal polymer corrosion inhibitor minimizes the corrosion of the set cement by CO₂ through filming action. The hydroxyapatite repairs the vugs and pores formed by corrosion on the set cement through adsorption of CO₂ which then produces laminated carbonate hydroxyapatite, thereby enhancing the corrosion resistance of the hydroxyapatite cement.