Patent ID: 9267075
Filing Date: 2016-02-23
CPC Classification: C09K,E21B

Claim Text:
1. A method of increasing the recovery of hydrocarbon fluids from a subterranean formation comprising injecting into the subterranean formation a composition comprising water, a cationic crosslinker, and a highly crosslinked expandable hydrophilic polymeric particle having anionic 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 greater than 0 to about 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 crosslinker then reacts with said expanded polymer to form a gel.