Prior to our arrival plugs had been set throughout the well to isolate zones and cement had been squeezed at 3,000’ to address annular pressure. However, the well continued to exhibit pressure and a CBL showed a micro annulus around 850’. The well was prepared by setting a bridge plug around 850’, perforating through the 4-1/2” casing at two locations just above the plug, and setting 2-3/8” tubing at the depth of the bottom perforation.
Three injection stages were run over a 36-hour period. Pressure was stepped up incrementally in the 1st stage to 800 psi and a significant volume of fluids were injected. The well was then shut in at pressure overnight to allow calcium carbonate to continue to form in leakage pathways. The next morning a 2nd stage was run. Pressure was quickly brought up to 400 psi to prevent damaging biomineralization that had occurred the previous day and seal any remaining leakage pathways. Pressure remained relatively constant during the 2nd and 3rd stages and the injection rate dropped steadily.
The flow rate began at 0.339 gpm in the 1st stage and ended at 0.007 gpm at the conclusion of the final stage, with a total of 206 gal injected. This constituted a 97.9% decrease in injectivity, implying significant sealing.
Bradenhead pressure was reduced to 0.8 psi immediately after the final stage and when tested again 6 days later had been completely eliminated (7-12 hour shut-in).
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