Statoil and its license partners in the Gullfaks and Oseberg area fields in the Norwegian North Sea Unit have acquired two new “Category J” jackup drilling rigs.Both sets of licensees will own the rigs, which are designed to work in harsh environments, in water depths of 70-140 m (229-459 ft), and to drill wells up to 10,000 m (32,808 ft). They are based on proven technology, although optimized, Statoil says, to allow for more efficient drilling and completion of subsea wells compared with existing jackups. The primary role will be in drilling and completion of production wells.
Samsung Heavy Industries will build the rigs and KCA Deutag Drilling Norway will operate them, with offshore operations set to start in 2016-2017. The initial operation contract, valued at NOK 900 million ($155 million), is for eight years, extendable by four three-year periods.
Statoil’s strategy is to rejuvenate its rig fleet, secure long-term rig capacity, and reduce drilling costs to improve recovery rates from its Norwegian fields.
Both Gullfaks and Oseberg have long-term drilling programs, and the new rigs will likely operate at these fields for a long period. Costs are expected to be lower as a result of the ownership model, and this is expected to allow more targets to be drilled that would otherwise not be economical.
Partners at Gullfaks are Statoil, Petoro. Partners at Oseberg are Statoil, Petoro, Total E&P, ConocoPhillips
Cat J --- new design rig
A jack-up is a mobile unit that floats during transport but rest on the seabed during drilling and well operations. This is made possible by lifting and lowering the legs of the unit, and the rig is lifted above the sea surface to minimize influence of waves during operations. The specially-designed category J rig is able to operate at water depths from 70 to 150 meters and drill wells down to 10,000 meters. It will be a workhorse primarily for drilling and completion of production wells. It is a tailor-made jack-up rig for operations in harsh environment on both surface and subsea wells in the shallow-water segments on the NCS.
Why Cat J?
The key to maintaining today’s production level on the NCS towards 2020 is improved recovery from existing fields and fast and efficient development of new fields. In order to implement these measures it is vital to secure a rig fleet which is adapted to suit the assignments and which can work more efficient.
To meet these challenges, sustainable cost competitiveness, drilling efficiency and sufficient rig capacity are key factors. Statoil has therefore developed a new mobile offshore drilling unit concept; cat J. This rig will be
customised for year-round production drilling in shallow-water depths. The goal is that the new rig will perform operations 20% more efficiently than the conventional rigs. This will reduce field development costs
and the rig fleet will be rejuvenated.
Technical aspects
Hull designers, topside suppliers, construction yards and drilling contractors have participated in the development of the cat J rig concept and will continue to develop this in an innovative design process.
The cat J conceptual design has the following key elements-
- Very competitive operational cost compared with existing rig fleet
- More efficient drilling with quadruple derrick
- Minimum weather downtime due to vessel motion in operation
- Low diesel consumption cost
- Lower wellhead fatigue exposure
- High flexibility for efficient drilling over wellhead platforms and subsea field development
- Facilitates for early production drilling on new field development projects
Main features:
• GustoMSC CJ70-X150-A concept is based on proven technology and equipment from Aker Solutions, National Oilwell Varco or TTS.
• Ultra harsh environment jack-up
• Test/service BOP and x-mas tree on cellar deck
• Facilitates for new fast-track X-mas tree size and system
• 1.5 derrick - simultaneous drilling and building stands
• Trip saver function --- possible to hang off blow out preventer (BOP) and riser (250 tonnes) on Texas deck
• Designed for Statoil’s subsea system on the NCS
• X-Y skidding cantilever 110 feet reach
• BOP riser tension systems are designed for both surface and subsea BOP operations
• High pressure high temperature (HPHT) operations (15k)
• Up to 150m water depth
• Class Notation: DNV 1A1 self-elevating unit and drilling unit (N)
Cat J has a double barrier philosophy for preventing falling objects and ensure well control. It is also designed to prevent environmental spills and assure improved working environment. It features a high level of redundancy in material handling, crane coverage and pipe handling as well as power generation and control systems.
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