P&A Application in Norway North Sea

Identification of problem

A client required isolation in the uncemented annulus behind a 7 5/8” liner that was run inside 9 5/8” casing.

Issues to overcome

For proper well control, the client could not remove the 5 ½” tubing in the well which had a 4.276” ID mule shoe on the bottom and could not establish sufficient injection into the annulus to squeeze cement or resin. This required a tool with a maximum OD of 4.0” to set inside 7 5/8” liner and seal out to 9 5/8” casing through perforations without circulating or squeezing from surface.

Application

Wel-lok™ STC was set in a perforated section of the 7 5/8” liner to isolate the wellbore out to the 9 5/8” casing.

Outcomes/Conclusion

This tool was qualified to 1,500 psi differential pressure in 7 5/8” x 9 5/8” casings at our testing facility in Houston, TX. For field deployment, the perforation guns used perforated both the 7 5/8” liner and the 9 5/8” casing. As a result, the Wel-lok™ STC did not achieve a positive pressure test in the field deployment as it was not designed or qualified to seal beyond the 9 5/8” casing.

About the application

The Wel-lok™ STC (Seal Through Casing) has been developed to achieve a gas tight V0 seal well annuli that cannot be achieved by traditional cement balance plugs. Run on electric line, this tool does not need surface pumping equipment to circulate the alloy in place. Due to its viscosity and density, once melted the liquid alloy will flow with gravity into the annulus. When it cools below its melting point it solidifies, expands and creates a gas tight seal across the entire wellbore. The entire process, from melting to solidification, takes place in minutes and the seal is ready to test within an hour.

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