Patent ID: 9139762
Filing Date: 2015-09-22
Classification: C09K

Abstract:
1. A method of increasing the recovery of hydrocarbon fluids in a subterranean formation comprising injecting into a subterranean formation a composition comprising water, and a highly crosslinked expandable hydrophilic polymeric particle having at least 0.5 mole percent cationic sites, wherein: i) said polymeric particle has an unexpanded volume average particle size diameter of 0.05-10 microns and a crosslinker content of about 1,000-200,000 ppm of labile crosslinker and about greater than 0 to 300 ppm of stable crosslinker, ii) said polymeric particle has a smaller diameter than the pore throats of the subterranean formation, iii) said labile crosslinkers break under the conditions of temperature and suitable pH in the subterranean formation to allow the polymeric particle to expand, and iv) said cationic sites adsorb to said subterranean formation thus making said particle resistant to washout.