fax 01-972-952-9435.References at the end of the paper. AbstractIn 1997, Statoil and Halliburton Energy Services, Inc. began jointly evaluating technologies that could be used to develop a revolutionary coiled-tubing and well-intervention system. This system, which will be deployed initially in the Norwegian sector of the North Sea, sets a new standard for drilling with conventional drilling rigs or coiled-tubing drilling units. The advanced well-construction system consists of a digitally controlled and automated coiled-tubing drilling system that uses a new advanced composite coiled tubing (ACCT) with embedded wires and a tractor-driven bottomhole assembly (BHA). This system enables the geological steering of complex, extended-reach wellpaths that were not previously achievable.This paper discusses a joint development project in which the operator and the service company worked together to design a fit-for-purpose system that met Norways stringent health, safety, and environment (HSE) requirements. The systems three major subsystems are discussed: the digitally controlled and automated surface equipment, the 2 7 /8-in. ACCT with embedded wires, and the drilling and intervention BHA. Test results from qualification and pilot wells are also included.

Claims can be found in technical literature for using Mono Diameter Expandable Liners in deepwater applications. In a technical review of the existing Mono Diameter Expandable Liner systems by various vendors, it is concluded that Mono Diameter Expandable Liner can be considered for using as a drilling liner if certain prerequisites as discussed in this paper are met. Further, the product can be used in a brown field development scenario, where no pore pressure surprises are expected. In any case, once drilling to target has been achieved, the product must be covered by a conventional casing. Proper risk evaluation before running in the hole is recommended, given the high per day costs associated with the deepwater wells. On the other hand, if the product has to be used for deepwater pre planning and casing design purposes, substantial increase in strength (collapse & burst of the pipe) will be required, without which the product will not qualify industry standard casing design criteria’s at the basis of design level. From design perspective, one time or multiple mono diameter expandable liner extension are the same and the key issue to address in using this product is meeting the collapse pressure requirements.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Barents Sea is an environmentally important ecosystem defined as part of the Arctic. The Norwegian environmental regulation is particular strict for this area, a zero discharge regime prevails. This paper describes the challenges of entering the area for exploration drilling. With reference to a recent operation (2005) a presentation of how the challenges were resolved is given. New procedures and new techniques were implemented to achieve compliance with performance expectations. The succeeding experience lead to important learning that has implications for future exploration drilling in such areas.

Statoil drilled 7 deepwater wells, including one sidetrack, on the Norwegian Continental Shelf from 2007 to 2009. The semi-submersible rig Transocean Leader was used for these drilling operations. All the wells were drilled and abandoned in a total of 460 days, some 135 days ahead of schedule. Gas and/or condensate were discovered in 6 out of these 7 wells. The wells were all drilled with higher efficiency compared to previous deepwater wells drilled on the Norwegian Continental Shelf. The water depth for the wells ranged from 950 m to 1350 m. In the planning phase, the proposed well designs were challenging. However, continuous improvement in drilling performance and risk management were achieved through comprehensive and systematic work in the multi-disciplinary project team of geologists and drilling engineers. Additional contributing key factors to success were good cooperation and planning between the offshore and onshore project team including personnel from the rig contractor and service companies. In the planning phase, early identification of technical challenges and solutions were discussed. Key learning from international deepwater projects in StatoilHydro and other operators were also highlighted. The geological and pore pressure prognosis for all the wells were quite accurate compared to the measured values during drilling and logging. This paper describes how deepwater exploration wells were planned and successfully completed with Transocean Leader. Good teamwork between offshore and onshore contributed to this success story.

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