Patent ID: 7866393

Claim:
A method of reducing fluid loss in a subterranean formation comprising: placing a lost circulation composition comprising a base fluid and at least one swellable elastomer selected from the group consisting of an acrylate butadiene rubber, a chloroprene rubber, a chlorinated polyethylene, a sulphonated polyethylene, an epichlorohydrin ethylene oxide copolymer, an ethylene vinyl acetate copolymer, a fluorosilicone rubber, a silicone rubber, a poly 2,2,1-bicyclo heptene, a crosslinked substituted vinyl acrylate copolymer, diatomaceous earth, a hydrogenated nitrile rubber, a fluoro rubber, a perfluoro rubber, a tetrafluorethylene/propylene, a starch-polyacrylate acid graft copolymer, a polyvinyl alcoholcyclic acid anhydride graft copolymer, and a starch-polyacrylonitrile graft copolymer in at least a portion of a subterranean formation comprising a lost circulation zone; allowing the swellable elastomer to at least partially swell upon contact with a fluid; and allowing the lost circulation composition to at least partially reduce the loss of fluid to the subterranean formation.