Patent ID: 6616753
Filing Date: 2003-09-09
Classification: C04B,C09K

Abstract:
A method of sealing a permeable subterranean zone penetrated by a well bore to prevent the uncontrolled flow of fluids into or from the zone comprising the steps of:(a) introducing a sealing composition into said subterranean zone comprised of a hydraulic cement selected from the group consisting of Portland cements, pozzolana cements, gypsum cements, slag cements and silica cements, sufficient water to form a slurry and a rapidly acting thixotropy providing gelling agent selected from the group consisting of compounds of the formula MaMb(SO4)2. xH2O, wherein Ma is a monovalent metal ion having an oxidation state of I, Mb is a trivalent metal ion having an oxidation state of III, and x is the number of moles of water of crystallization in the range of from 0 to 24, and (b) allowing said sealing composition to remain at rest in said zone whereby said sealing composition rapidly gels and then sets into a hard impermeable mass therein.