1 Drilling in skid-off (tender assisted) mode from a cantilever jack-up has been done on several occasions worldwide including the North Sea (ref. 1). This paper describes the utilization of the "MAERSK GALLANT", an MSC-C.T62S jack-up drilling rig, at the FROY Field in the North Sea in Skid-off Mode. FROY is located 35 km SE of the Frigg Field off Norway in a water depth of 120 m. The field is developed with a light, unmanned platform. The topside is comprising a well bay area with 15 slots and a process area with a test separator, a gas/liquid separator and export pump only. No drilling facilities are built on the WHP. Four wells were pre-drilled with a semi-submersible rig. Tie-back and completion of these first four wells and completion and drilling of the six remaining wells were performed by the jack-up "MAERSK GALLANT" in skid-over mode (fig. 1). Several development scenarios were studied. The reason to develop this field with this alternative, even in this extreme environment, was to minimize weight and cost; the jacket structure is 6,000 mT and the topside only 2,375 mT. It has also been a focus in the design of the skid-over solution itself and thereby make it more or less "field specific", compared to previous skid-off solutions for ultra harsh environment jack-ups (ref. 1). Another consideration was the water depth of 120 m, which is a North Sea record for jack-ups, and the associated relative movements between the production platform and the rig. The end result, however, was a highly flexible design which can be utilized on a large number of field developments with only minor adjustments. All setting up of drilling facilities on the platform were done from the jack-up without any assistance from the platform, crane barges or similar. As for the drilling operation all "support" from the production platform is two skidding beams with a spacing of 14.0 m (46 feet). The design optimization was done as a joint effort between the Operator (ELF NORGE) and Maersk Drilling. The success of the project emphasized the importance of close cooperation between the operator and the contractor as early as possible in connection with field development projects.
Summary BP and Maersk Drilling entered into a unique collaborative arrangement in early 2013 to develop the design for a deepwater drilling rig that is specifically aimed at conducting operations on wells with greater than 15,000 psi pressures. This paper describes how this collaborative effort was conducted. Operator and contractor each contributed expertise and information to the project and defined a joint vision of transforming how functional requirements are set and how the design of this rig would be developed. A set of relationship principles was agreed and a joint project team was formed in Houston with engineering support from contrator's technical organization in Copenhagen. An executive committee, with senior leadership from each organization, was established to provide guidance, challenge and governance. To start the design process, workflow during the well construction process was layered on top of the foundational requirements of operator's prospect inventory. Starting with a cleaner sheet of paper, the integrated team's conversations focused on inherently safer design and improving operability, efficiency, maintainability and reliability. The initial focus was on innovation and possibilities before driving toward agreement on the functional specification and rig design. The team strove to address challenges faced in the deepwater drilling industry today, at the same time continually testing their ideas for benefit. After more definition work, the opportunities were run through a detailed evaluation model to inform selection of design features and potential equipment suppliers. Major equipment suppliers and operator service companies have assisted with the development of rig functional requirements and the shipyard specification. Operator and contractor contributed their learning from previous rig builds, intakes and operation including five and ten year re-certifications into the design. Supplier selection for long lead technology development and qualification of equipment commenced in 2013 and is expected to culminate with a yard selection in 2015. As a result of this collaboration, operator and contractor better understand the needs and drivers of each other's business and have leveraged this knowledge into a more effective working relationship. Significant work remains to construct the rig and deliver it into operation. However, there is a strong belief this next generation deepwater drilling rig will provide enhanced capability, performance and value to both operator and contractor.
Drilling with jack-ups in harsh environments has moved into deeper and deeper water during the last 10 years. Previously 90 m was considered the maximum whereas up to 150 m water depth is now feasible. In addition several new features are now available on harsh environment jack-ups which increase the drilling efficiency by up to 25% compared with the more conventional jack-up types. This paper describes the process of creating the next generation deepwater jack-up drilling rig, and the results and operational experience with the Maersk "I" class rigs - the Maersk Innovator and the Maersk Inspirer. The Maersk Innovator has been in operation for approximately 18 months and the Maersk Inspirer is in transit to the North Sea. The Maersk Inspirer is contracted to start operating in February 2005. Design Phase Maersk Contractors operates a number of ultra harsh environment rigs in the North Sea (NS). Based on experience with these rigs the functional requirements to the next generation of ultra harsh environment jack-up rigs were developed. The overall focus was to further improve the safety level onboard from previous rigs and provide more value for money to the clients. This can be obtained by reducing the need for costly modifications for specific operations and improvement of the overall drilling efficiency in the design. A large number of NS operators were consulted in order to obtain their view of the ideal rig in the future. More than 650 suggestions were formally received from the rig crews on the existing fleet, of which more than 450 were incorporated in the final design. In addition a number of presentations/discussions were conducted onboard the rigs in order to get "real life" feedback and comments. A 1:1 mock-up of the drill floor with simulated work situations was used to gather valuable input to the layout. The modifications, which have been required on Maersk Gallant (an MSC-CJ 62 design) to operate with extended reach/skid-off (ref. 1) and at increased water depth of 125 m at Statoil's Huldra Field, were evaluated. Use of the rigs in subsea and production mode was also considered. The MSC-CJ70 was chosen as the basic design and the concept was developed together with MSC. This included an XY cantilever system which provides opportunities to increase efficiency and introduce improvements on the drill floor (ref. 2). The Rigs General/Structural performance. The rigs have a leg length of 205 m with a permanent skirted spudcan which gives a water depth capability in the NS of up to 150 m (Fig. 1). The variable deck load at 150 m water depth is 4000 mT. At lower water depth the deck load is significantly higher, up to 10,000 mT depending on the seabed conditions (Fig. 2). At the Shell Goldeneye location in 120 m water depth the variable deck load was 9,000 mT, which was utilised to a great extent. The 120-man accommodation is placed in a V-Shape around the forward leg with a sleeping side and a "noisy side" with offices, mess room, recreation rooms, etc., This together with the location of all ventilation ducts, etc. in three separate houses next to the legs gives a very large useable deck area of 2,500 m2 compared to 1500 m2 on rigs with similar hull sizes (Fig. 3a). A forklift is used on the main deck to reduce the number of crane lifts and thereby improve safety. Below deck the layout is optimised with regard to safety and working environment with two separate engine rooms, pipe trunk and straight escape routes enabling protected escape routes from anywhere on the rig (Fig. 3b).
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