Patent ID: 7674333

Claim:
A sealant having a specific gravity in the range of from about 0.7 to about 1.6 for heavy oil and/or coal bed methane fields, said sealant comprising a) about 20 to about 50% by weight of a binder comprising about 2 to about 25% by weight of MgO or an oxide of Fe and further comprising about 10 to about 40% by weight KH 2 PO 4 , b) about 1 to about 10% by weight of silica fume, c) 37.6 to 49.5 percent by weight of one or more filler selected from the group consisting of fly ash and calcium silicate, and d) chemically bound water present in the range of from about 9 to about 36% by weight of said sealant.