Patent ID: 6257336
Filing Date: 2001-07-10
Classification: C04B,C09K

Abstract:
In a method comprising circulating a clinker cement in a well bored through at least one geological formation of a certain permeability wherein a filtrate reducer additive is employed to limit filtration through the walls of said well and to limit loss of an aqueous element from the clinker cement, the improvement wherein said filtrate reducer additive comprises a hydrophilically and hydrophobically modified galactomannan substituted, on the oxygens, with both at least one hydrophillic radical and hydrophobic radical, said hydrophobic radical being of the general formula (1): ##STR3##whereA=a linear or branched oxyalkylenic O--C.sub.p H.sub.2p group where p is 2 to 4, n=0 to 30; m=0 or 1 where m may not be zero unless n is zero,R=a linear or branched (hydrophobic) alkyl radical, optionally ethylenically saturated, having between 10 and 32 carbon atoms, the hydrophobic radical being present in a degree of substitution of 0.00001 to 0.0009 hydrophobic units per unit of anhydroglucoside, and wherein the molecular mass of said hydrophobically modified galactomannan is less than 2,000,000 dalton.