| 摘要 |
A method to improve the efficiency of scale dissolution in a formation containing multiple productive intervals (20, 22, 24, 26) where variable density liquids are utilized. Initially, a liquid composition sufficient to solubilize an alkaline-earth metal sulphate scale deposit is directed into a wellbore (10) thereby contacting scale in one productive interval of the formation. Thereafter, a second scale solubilizing liquid having a density less than the first liquid is directed into the wellbore (10) thereby contacting additional perforations (14) and a higher interval. These scale solubilizing liquids with varying densities are allowed to remain in contact with perforations (14) and productive intervals (20, 22, 24, 26) communicating therewith for a time sufficient to solubilize the scale deposit thereby efficiently removing said scale deposit from perforations (14) and productive intervals (20, 22, 24, 26) at two different levels.
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