| abstract |
A high-temperature earth formation is acidized by injecting down a well and into the formation a water-soluble ester of an organic carboxylic acid which forms a calcium salt which is also watersoluble. The formation should be at a temperature of at least about 200* F., and preferably at least about 300* F. Water may be injected before, after, or with the ester. The well is preferably shut-in after injecting the ester to permit more complete hydrolysis of the ester before the well is returned to its usual operation. Various combinations of esters or combinations of esters and free acids can be used. The ester may be injected as a solution in aqueous or nonaqueous solvents. Preferred esters are methyl formate and ethyl acetate. |