additives to vaetskefoerlust, cementuppslamning innehaallande additives, foerfarande foer framstaellning of cement and foerfarande foer cementing of oil and gasborrhaal

摘要

An improved water loss control additive for hydraulic cements, particularly hydraulic cements used in subterranean well bore cementing operations, is disclosed. The additive comprises an aqueous solution comprising a tetrapolymer of N-vinyl-2-pyrrolidone, acrylamide and/or methacrylamide, sodium 2-acrylamido-2-methylpropane sulfonate and/or 2-acrylamido-2-methylpropane sulfonic acid, and acrylic acid or sodium acrylate; a base; and electrolyte and a surfactant.