BioSqueeze Inc. was contracted by an operator to eliminate annular pressure in a well in the process of being abandoned. Prior to our arrival, the well was prepared by perforating at 600 ft through the 3-1/2 in casing string, setting a removable bridge plug just below the perforations and installing 2-1/16 in tubing.
Our team arrived on site and began pumping our biomineralizing solution down the well and into the leakage pathways in the cemented annulus. Seven injection sequences were then run over a three day period. At the conclusion of each sequence pressure falloff was measured to evaluate progress.
Maximum pressure specified by the operator was 600 psi. Pressure quickly rose to 500 psi during the first sequence before dropping to around 16 psi. Pressure would not rise over 60 psi during the second sequence and it was discovered that a leaky ball valve was responsible. The ball valve was then replaced and for sequences four through seven pressure quickly rose to 600 psi.
The flow rate began at 0.8218 gpm at the start of the first sequence and ended at 0.0069 gpm at the conclusion of the final sequence. This constituted a 99.16% decrease in injectivity, which implied significant formation of calcium carbonate in the leaking annulus.
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