反相乳液聚合法合成凝胶微球及其封堵性能评价

以丙烯酰胺（AM）和2-丙烯酰胺-2-甲基丙磺酸（AMPS）为原料，用反相乳液聚合法合成了凝胶微球（OBMG）。并采用红外光谱（FTIR）、核磁共振氢谱（1HNMR）对其结构进行了表征。详细考察了反相乳液体系中复合乳化剂的HLB值、油水比、单体物质的量比、单体总浓度、交联剂浓度对封堵效果的影响。结果表明，合成OBMG的最佳条件为：复合乳化剂的HLB值为5.0、油水比为0.64∶1、交联剂浓度为单体总质量的0.07%，单体总浓度为30%。在此条件下产物的单位压差漏失量降低率最大为80%。同时研究了凝胶微球加量对油基钻井液封堵性、电稳定性和表观黏度的影响。实验结果表明，凝胶微球加量为2%～3%时，钻井液的封堵效果最佳，说明其有利于提高乳液的稳定性。在油基钻井液中，OBMG封堵效果优于改性沥青和树脂微球。

Gel Microsphere: Synthesis through Inverse Emulsion Polymerization and Evaluation of Its Plugging Capacity

A gel microsphere (OBMG) was synthesized with acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS) through inverse emulsion polymerization. The molecular structure of OBMG was characterized by infrared spectrum (FTIR) and proton nuclear magnetic resonance spectrum (1HNMR). Effects on the plugging capacity of OBMG by several affecting factors, such as the HLB value of the emulsifiers in the inverse emulsion system, oil/water ratio, molar ratio of the monomers, the total concentration of the monomers as well as the concentration of the crosslinking agents, were fully investigated. The optimum synthesis condition was found as follows:HLB of the compound emulsifiers=5.0, oil/water ratio=0.64:1, the concentration of the crosslinking agent=0.07% of the total concentration of the monomers, and the total concentration of the monomers=30%. Using gel microsphere produced under these conditions to control mud losses, percent reduction in volume of mud losses under unit differential pressure was 80% (maximum). Study on the effects of the concentration of OBMG on the plugging performance, electric stability and apparent viscosity of oil base muds indicated that at OBMG concentration of 2%-3%, the drilling fluid had the best plugging capacity, meaning that OBMG is beneficial to improving the emulsion stability. In oil base drilling fluids, the plugging performance of OBMG excels modified asphalt and resin microsphere.