| abstract |
A method of producing a gel of an organic liquid, using a metal phosphate ester in which all of the reagents are substantially free of water and pH-affecting substances. The gel is particularly useful in fracturing subterranean formations by entraining a solid particulate proppant therein and pumping the resultant mixture into the subterranean rock formation at sufficient pressure to fracture the formation. The organic liquid is preferably a hydrocarbon such as diesel or crude oil, and the metal phosphate ester is preferably an aluminum phosphate diester. The metal phosphate diester may be prepared by the reaction of a triester with P2O5 to produce a polyphosphate, which is then reacted with an alcohol to produce a phosphate diester. The latter diester is then added to the organic liquid along with a non-aqueous source of aluminum, such as aluminum isopropoxide in diesel, to produce the metal phosphate diester. The conditions in the foregoing two reaction steps are controlled to provide a gel with good viscosity versus temperature and time characteristics. |