Fast moving workover rig speeds production from Bahr Essalam
A key component in the development drilling campaign is the first offshore application anywhere of the fast moving workover rig.
Early last month, first production was due from ENI Gas BV’s Bahr Essalam development, 110-km offshore Tripoli. The project is harnessing offshore gas and condensate for export both to Libya and the Italian grid via a subsea trunkline to Sicily.
A key component in the development drilling campaign is the first offshore application anywhere of the fast moving workover rig (FMWR), designed and supplied by Eiffel, a Paris-based subsidiary of Eiffage. The company delivered the FMWR last fall and it has been operating since January on Sabratha, Bahr Essalam’s Phase 1’s central production platform, which is in 190 m of water.
Thanks to this equipment, ENI Gas has advanced first gas deliveries from the platform by four months.
Rig-up test in Eiffel's yard in Fos-sur-Mer, southern France.
The FMWR is fully autonomous and can also operate while the hook-up and commissioning of the platform is being completed. Also, the rig does not need the assistance of a barge that would have been immobilized on one side of the Sabratha platform.
The FMWR will be drilling 8 1/2-in. or 6 1/8-in. sections, and will complete the wells with 7-in. liner or 4 1/2-in. tubings. It can drill to depths of up to 24,000-ft with an extended reach of up to 3 mi.
The rig’s 200 tonne setback load capacity can accommodate the whole tubing string required for the operation, saving time in laying down the drill pipes and picking them up again. It can also handle triples, which means less time pulling out and running in hole.
The FMWR can also be used as a conventional drilling rig, which can work with oil-based mud, its mud pit capacity being around 1,500 bbl. Mast capacity/reach is 250 tonnes.
Rig setup
The FMWR comprises four main modules:
• Electric generators and utilities (fuel oil, pressurized hydraulics, and air)
• Mud tanks and mud treatment utilities, making up the sub-structure supporting the drilling floor (mast, winch, rotary table, BOP control unit, and drilling foreman’s office)
• High-pressure mud pump module, the structure of which serves as support for the rig’s crane
• Pipe rack, supported in part by the mud tanks and in part by the mud pumps.
These modules are girthed to allow their simultaneous relocation by means of a hydraulic jack with grippers.
The FMWR is a fully flexible and modular drilling rig that provides cost-effective rig-up (typically in five days). It can be mobilized and demobilized using a standard supply boat with a deck clearance of 100-ft. Lifting capacity required offshore is minimal. The set-up principle is first to rig up the FMWR’s crane, weighing 12.6 tons. This is then employed to rig up the other modules, which have a maximum weight of 14 tons.
The rig complies with the highest quality and health and safety standards. It is also designed to operate in H2S and CH4 conditions. It includes a zero discharge tank and minimum noise level requirements. It is also designed to withstand the most extreme wind and earthquake condition as recorded over the past 100 years. •
