BSI was contracted to eliminate surface casing vent flow (.46 m3/day) on a well being abandoned in Alberta.
Abandonment operations began in 2021, with multiple attempts to eliminate SCVF following shortly after including casing expansions, cement squeezes, and casing expansion plugs but vent flow persisted, prompting non-routine abandonment.
The well was perforated from 473-471 mKb (118 spm, 10° phasing), with a removable bridge plug set at 476mKb, and a tension set packer run in hole with tail pipe to 473 mkB.
Injection began on the 177.8 mm x 244.5 mm annulus with a series of squeezes pumped over the course of four days. Pressure was increased gradually initially and then held constant for the duration of each stage, during which the pump rate decreased, indicating leakage pathways were being sealed. The pump rate continued to decrease with each subsequent stage as crystalline calcium carbonate formed in leakage pathways throughout the cemented annulus.
The pump rate was reduced by 99% from the start to the conclusion of treatment, pressure falloff measured at the end of each stage was reduced from 366 kPa/min to 24 kPa/min, both good indicators of successful sealing. Vent flow was reduced to 0.0673 m3/day by the end of treatment and bled down to 0 m3/day several days later, allowing the well to be permanently abandoned.
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