Improved Operations With a High-Efficiency Jackup
- Dennis Denney (JPT Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- April 2007
- Document Type
- Journal Paper
- 51 - 52
- 2007. Society of Petroleum Engineers
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This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 105883, "Improvements in Operations Using a High-Efficiency Jackup," by Gordon Hart and Allan Ramsing, Mærsk Contractors, prepared for the 2007 SPE/IADC Drilling Conference, Amsterdam, 20-22 February.
A high-efficiency ultralarge jackup rig was used in operations offshore Norway for ConocoPhillips at the Ekofisk field. The rig uses “x-y” cantilever skidding, and it is rigged with a quadruple der-rick with dual standbuilding capability and space for casing racking.
The Marine Structure Consultants CJ-70 type jackup drilling rig Mærsk Innovator is drilling development wells on the Ekofisk 2/4M platform for ConocoPhillips Norway. The rig is to drill 25 of 30 planned wells over a 3- to 4-year period. The other five wells were drilled with the Mærsk Gallant. The wells are a mixture of deviated (up to 80° inclination) and horizontal wells. The program with the Innovator commenced in late November 2005. First, 10 conductor strings were drilled and set. Second, a cuttings-reinjection well was drilled and completed to allow self-sufficient operation in cuttings handling. The final step is drilling and completing the wells. As of November 2006, eight producing wells had been drilled and completed. A further program of batch-setting eight conductor strings was completed during the summer.
In addition to operational performance, these rigs were designed with features to improve safety and environmental performance.
- Decks clear of ventilators and crane pedestals—allows use of a forklift truck for container handling.
- Automated pipe-handling system.
- Enclosed moonpool.
- Fully enclosed large-capacity mud pits.
- Automated mud-mixing and solids-control systems.
- Dual engine rooms—allows maintenance in “quiet” room.
- Zero-discharge system.
- Quiet-zone accommodations.
- Driller’s cabin comprising three ergonomically designed workstations.
Increased efficiency was the result of the following.
- Dual pipe-handling equipment: racking machines and iron roughnecks (two each servicing the well center and the foxhole).
- Remotely operated pipe-handling machine for transferring tubulars from the cantilever to the drill floor.
- Casing run in stands.
- The derrick designed for fourbles of Range-II or thribbles of Range-III drillpipe, resulting in 25% fewer connections.
- Variable deckload with a capacity in excess of 10 000 tonnes.
- Three large-capacity cranes with redundancy to cover deck areas.
- Large deck space and storage capacities for all equipment and consumables.
- Cuttings-handling and slurrification systems.
- Slurry-injection system.
- Proprietory x-y cantilever-skidding system
- Moonpool area with capacity to run coiled-tubing or wireline operations offline through a secondary moonpool.
Of the 54 wells used in the database, the Gallant drilled 11, a Mærsk giant-class rig drilled four, and the remainder was drilled with platform drilling. For the purposes of this comparison, only the Gallant performance was considered.
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