BSI was contracted to mitigate pressure on the 7” x 4-1/2” annulus on a well being abandoned in Pennsylvania. Casing expansion and micro-fine cement were used in prior unsuccessful attempts to eliminate the leak. To prepare the well for biomineralization, a bridge plug was set at 580’, three notches were cut through the 4-1/2” casing just above the plug, and 2-3/8” tubing was run to the bottom cut.
Pressure was stepped up to 900 psi in the 1st stage, during which flow decreased significantly. The well was then shut in at pressure overnight to allow the biomineralization process to continue closing leakage pathways.
Injection resumed the next morning with pressure again brought to 900 psi. A new leakage pathway was opened 60 min into pumping, which drastically increased flow, allowing a significant volume of fluids to be injected. Pressure was increased incrementally to 750 psi in the final stage. Flow decreased steadily for the next 70 min, at which point the well was thought to be effectively sealed.
The flow rate began at 0.309 gpm in the 1st stage and ended at 0.009 gpm at the conclusion of the 9th stage, with a total of 91 gal injected, a 97.1% decrease in injectivity. LEL prior to treatment was 71% and monitoring post-treatment confirmed it had been eliminated.
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