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

Abstract

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.