Abstract
This case study provides an overview of the Coiled Tubing (CT) operation performed for Statoil on the Heidrun field in 2002. The operation covered cleaning of a downhole sand control screen utilizing the Roto-Jet Technology, followed by installation of new sand screens inside the existing screens and performing a circulating gravel pack with coiled tubing.
The reason for this well operation was to repair a sudden and massive sand control breakdown. It was anticipated that this resulted from plugging of the gravel pack screens and/or a gravel pack packer failure. The well was producing 1500 Sm3/day with a water cut of 30 % prior to detecting the sand production. The objective of this intervention was to stop the sand production by installing 3-1/2" screens inside the damaged 5-1/2" screens, and perform a circulating gravel pack between the old and new screens.
The operation was conducted using a compensated CT tower allowing handling and running of jointed tubulars. A total of 6 runs with 2-3/8" coiled tubing was performed to clean out sand, remove fines/kill pill behind the existing screens, drift the well prior to installing a gravel pack packer, run new screens and perform the gravel pack operation, install a straddle across the gravel pack port and acidize. To be able to deploy screens into the well, it was temporarily killed with a specially designed kill pill.
After the CT operation, additional acid stimulation has been performed to remove remaining kill pill and increase the PI. The well is now producing 700 Sm3/day. The CT operation was performed in 21.2 days, while the platform was drilling simultaneously.
