Preparation of Microparticle Gels and their Application in Enhanced Oil Recovery

Expandable polyacrylamide micro particles were synthesized by an inverse-emulsion polymerization process using iso-octane as the oil phase, polysorbate-80 and sorbitane monooleate-80 as surfactants, acrylamide monomer, two different crosslinker/telechelic oligomers, and deionized water. The particles were designed to be oil reservoir deep diverting gels, which are initially constrained by one or two kinds of crosslinker, one of which produces and maintains the micron sized gel network particle so that the water-dispersed particles can penetrate porous geologies with small radii permeability. Under the stimuli of pH or temperature changes, a second labile crosslinker could degrade to decrease the degree of crosslinking. The change in network crosslink density allows the polymeric particle network to expand to many times its original size or change in its solubility, which can then block the geologic flow field pore throats and direct the injection of water into untapped field zones. The properties of microparticles with different crosslinkers were compared, mainly focusing on their swelling and rheological properties, and a core flood test