wel-lok TDAP
Permanently seals annulus during well construction
Page last modified
November 25 2024
The wel-lokTM TDAP (Thermally Deformable Annular Packer) is a downhole tool developed to provide a permanent gas-tight seal in the annulus between casing strings. It is run as part of the original casing string on the inner casing before cementing. After cementing the production tubing in place, the TDAP is set by running a chemical reaction heater inside the casing to melt a specialized bismuth-based alloy. This alloy has a low viscosity when melted, allowing it to flow into microannuli in the cement. As it cools and solidifies, the alloy expands to create a seamless, non-elastic seal that isolates the annulus. The wel-lok TDAP provides a preventative solution by sealing the annulus early in the well's life before issues like sustained casing pressure occur due to cement degradation over time. Its bismuth-based alloy is non-corrosive and withstands exposure to H2S, CO2, and acids. The wel-lok TDAP eliminates the need for future remedial cement squeezes or other interventions to address annular gas migration and sustained casing pressure.
Pros & Limitations
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Preventative tool to seal annulus and eliminate future gas migration
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Non-corrosive bismuth alloy seals unaffected by H2S, CO2 or acids
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No moving parts for high reliability
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Customizable for API and non-API casing sizes
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Quick setting time
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Permanent sealing solution
Specification
| Specification Title | Specification Description |
|---|---|
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Inner Casing Sizes
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4 1/2 in, 5 1/2 in, 6 5/8 in, 7 in, 9 5/8 in, 13 3/8 in
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Outer Casing Sizes
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7 in, 9 5/8 in, 10 3/4 in, 13 3/8 in, 20 in
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Heater OD Sizes
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3.5 in, 4.25 in, 4.5 in, 5.5 in, 7.625 in, 10.75 in
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Pressure Rating
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Up to 10,000 psi differential, 20,000 psi maximum tool rating
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Temperature Range
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0 - 175°C
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Conveyance Methods
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Eline, Slickline, Coiled Tubing, Drill Pipe
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Casing Grades
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All grades
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Well Deviation
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0 - 88° at setting depth
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