环境友好型交联酸的性能及其反应动力学

Performance and Reaction Kinetics of Environmental-Friendly Crosslinked Acid

摘要:

针对高温深层酸压改造过程中常规酸液体系与岩石反应速度快、腐蚀性强以及环境污染等问题，以乳酸、葡萄糖酸、聚乙烯亚胺(PEI)及稠化剂丙烯酰胺类聚合物等为原料，采用溶液共混法制备了一种环境友好型耐高温交联酸EAC-1。结合FTIR、流变测试、SEM等分析了乳酸与葡萄糖酸混合形成的复合酸溶蚀CaCO3的协同作用机理以及交联酸EAC-1的流变性、微观结构以及破胶性能，明确了交联酸的反应速率常数及其反应动力学方程。结果表明，当乳酸及葡萄糖酸物质的量比为1:1时，乳酸和葡萄糖酸可与Ca2+通过共价键作用形成一种具有高溶解度的螯合物，使残酸中无二次沉淀生成；170 s-1、110℃下交联酸黏度保持在50 mPa·s以上；交联剂PEI与稠化剂形成的立体网状结构保证体系具有良好的耐温耐剪切能力，且交联酸破胶均匀，无残渣，破胶液黏度仅为4.2 mPa·s；EAC-1的反应速率常数比以盐酸为主体酸的交联酸HC-1至少小1个数量级，表明EAC-1交联酸具有良好的缓速性能，有利于延长酸液有效作用距离。

Abstract:

To solve the problems such as high-rate reaction with rocks, strong corrosion and environmental pollution of conventional acid fluids in acid fracturing of high temperature and deep reservoirs, an environmental-friendly crosslinked acid (EAC-1) with heat resistance was prepared by solution blending method with lactic acid, gluconic acid, polyethyleneimine (PEI) and thickener acrylamide polymer as raw materials. The synergistic mechanism of CaCO3 dissolved by complex acid with lactic acid and gluconic acid, rheology, microstructures and gel breaking properties of crosslinked acid (EAC-1) were analyzed by FTIR, rheological test and SEM, etc. The reaction rate constant and reaction kinetic equation of crosslinked acid were also determined. The results showed that when the molar ratio of lactic acid to gluconic acid was 1:1, lactic acid and gluconic acid could form a high-solubility chelate with Ca2+ through covalent bond, and no secondary precipitation happened in the residual acid. The viscosity of crosslinked acid could maintain above 50 mPa·s at 170 s-1 and 110℃; the three-dimensional network structure in acid fluid formed by PEI and thickener improved the temperature and shear resistance. The crosslinked acid was broken evenly without residues, and the viscosity of gel breaking fluid was 4.2 mPa·s. The reaction rate constant of EAC-1 was at least one order of magnitude less than that of HC-1 with hydrochloric acid as the main acid, showing that crosslinked acid (EAC-1) had good retarding effect for prolonging the effective action distance of acid fluid in acidizing fracturing.