Annular pressure relief technology

Successful elimination technology of annular pressure

Operator : Noble Energy
Basin : Denver-Julesburg
Plug type : Abandoned well plugging
Plug Length : 600 feet
Depth to top of plug : 820 feet
Tail pipe : 2.375 EUE fiberglass oil pipe
Release pressure : 1000 psi

Challenge : In an older vertical well in the Denver-Julesburg Basin, gas was migrating through the annulus between the 8.625" surface casing and the 4.500" production casing. Traditional abandonment methods were not effective in eliminating gas migration.

Solution : The Prenup plug placement aid was selected to allow accurate and undisturbed plug placement. The Prenup tool enabled the use of an optimized cement slurry with a thickening time equal to the placement time. A Citadel jet diverter was also used to perform a 360° wellbore cleanout, specifically cleaning the washout area below the surface casing shoe.

Results : The cement plug was successfully set and the work string returned to the surface without incident. The top of the cement plug was less than 20 feet from the designed top. After one week of monitoring the well, the surface pressure was zero. The use of the Prenup plug placement aid successfully plugged the abandoned well and eased future remedial work.

“The Prenup tool allowed us to eliminate gas migration in an older well,” said DJ, production engineer at Noble Energy. “We are pleased to have a tool that can set reliable plugs in challenging applications.”