METHODS AND COMPOSITIONS FOR ACIDIZATION IN A WELLBORE

摘要

Improved acidization methods and compositions are provided wherein the compositions comprise an aqueous solution comprising one or more esters or polyesters of hydroxy acid or of glycerol. The solution may be placed in a well where the esters or polyesters undergo hydrolysis. The hydrolysis of the esters or polyesters occurs at a slower reaction rate than that of several other known acidization esters, such as diethyleneglycol diformate, at temperatures higher than 600C or even higher than 1000C. Thus, the acidization solution may be distributed substantially throughout a region in a well where acidization is required before hydrolysis is completed, despite being exposed to relatively high temperatures. The hydrolysis may result in the slow release of an acid that is capable of consuming all or most of an undesirable substance in the well, e.g., a filter cake.