Water injector well is unable to maintain pressure support
Production was declining in a mature field in the Norwegian sector of the North Sea because a water injector well was unable to deliver enough rate at the depth required to effectively sweep oil through the reservoir.
The injector well was believed to have two problems. First, as the field aged, the injection point for efficient pressure support moved deeper into the reservoir, but high-permeability upper zones continued to take the bulk of the injected fluid. Second, sand and debris hampered injectivity in the lower zones. Although injector wells do not usually experience sand influx, the operator believed that rapid injection shutdowns destabilized the sand, and subsequent crossflow allowed sand to enter the injector.
The operator considered sidetracking the injector to restore sweep efficiency with more reservoir contact but asked Schlumberger for a faster, less costly option.
Close old injection sleeves and shoot new perforations
The injector well had been completed with sliding sleeves, so engineers developed a plan to close the upper sleeves, clean out accumulated sand, and add new perforations near the toe.
Because the sleeves had not been shifted in more than 15 years, the first step was to remove debris and scale that might prevent shifting. The Jet Blaster service was run to highly energize the cleaning fluids, and the ACTive Xtreme tool to optimize solids removal at flow rates as high as 420 l/min [2.6 bbl/min].