Arctic Offshore Technology Assessment IMVPA of Exploration and Production Options for Project No. C-0506-15 Cold Regions of the US Outer Continental Shelf EXECUTIVE SUMMARY Objective The objective of this study is to deliver an assessment of oil and gas technology that may be applied to cold regions of the United States Outer Continental Shelf (OCS). Advances in harsh environment offshore exploration and production technology have made it economically and technically feasible for projects to proceed in ice-covered waters. This study assesses the current state of offshore technology in arctic and sub-arctic regions. The results of this assessment are then used to provide insight and guidance into existing/future exploration and development technologies that might be applied on the US OCS, in particular those areas in the Beaufort, Chukchi and Bering Seas. The work covers exploration structures, bottom-founded and fixed production concepts, floating production concepts, terminals, pipelines and subsea facilities, and also touches on other technologies that might be relevant to Alaskan OCS exploration and development. Assessment Methodology This study draws on a review of current state-of-practice and state-of-the-art used in, or proposed for, arctic and sub-arctic offshore development areas. Assessments of exploration and production options are primarily based on technical feasibility. As appropriate, other aspects have also been considered, including constructability, capital costs, environmental considerations, operations, maintenance and repair, abandonment and decommissioning. Given the large geographic area encompassed by the Beaufort, Chukchi and Bering Seas, location scenarios were adopted to help focus the assessments. These locations were chosen based on current and historic activity and interest (including lease sales, drilling, studies, projects, etc.) and water depths (given the general differences in offshore facilities configuration with water depths). Overall applicability of the technology to the region of interest was also considered. 01/31/2008 Page i of xxvi Rev. 0 Arctic Offshore Technology Assessment IMVPA of Exploration and Production Options for Project No. C-0506-15 Cold Regions of the US Outer Continental Shelf Technical Feasibility Bottom-Founded Structures In multi-year ice areas of the Alaskan OCS, there are bottom-founded, e.g., gravity base structure (GBS), solutions that would be considered safe and economical up to around 250 ft (75 m) water depths when foundation properties are good, and up to around 200 ft (60 m) water depths when foundation properties are relatively weak. There are no known bottom-founded platform design solutions for water depths greater than 330 ft (100 m) that could be deemed workable or proven for multi-year ice areas. In the more southern areas, where multi-year ice is absent and only first-year consolidated ridge loadings are possible, bottom-founded solutions out to 500 ft (150 m) water depths are potentially viable. Jacket & Jack-up Structures The ice reinforced jacket platform was first successfully used in sea ice in the mid 1960’s for Cook Inlet, Alaska developments. Previous studies have suggested that jacket structures are suitable for areas of the Bering Sea. However, these studies did not consider the vibration responses associated with the dynamic ice loading. Jacket type structures could likely be made to work in light first-year ice and in water depths less than 200 ft (60 m). However, the jacket structure’s potentially poor response to dynamic loading and the need for conductor system protection are significant design issues for application in the Bering Sea. Current design practices and understanding of jacket design make their application unsuitable for the Beaufort and Chukchi Seas. Developments in jack-up technology and the advancement of ice maintenance programs indicate that the operating range and season of jack-up exploration could potentially be extended in the Bering Sea. Ice Islands Grounded ice islands have been used successfully as exploration drilling structures in nearshore areas of the US and Canadian Beaufort Sea. In practice, operational ice islands have been employed in water depths of up to 25 ft (7.6 m) in the Beaufort Sea. 01/31/2008 Page ii of xxvi Rev. 0 Arctic Offshore Technology Assessment IMVPA of Exploration and Production Options for Project No. C-0506-15 Cold Regions of the US Outer Continental Shelf Based on work sponsored by the MMS, the use of operational ice islands might be achieved in water depths of up to approximately 30 ft (9 m). The MMS Ice Island Study (2005) suggests that “incremental improvements in equipment capacity with higher productivity would allow islands to be constructed into deeper water and it is considered that 40 ft (12 m) water depth should not present a problem”. The use of ice islands in the nearshore Chukchi would likely be infeasible due to the unstable and unreliable landfast, or contiguous, ice zone. Ice islands would be generally infeasible for Norton Sound due to its warmer and shorter winter season. However, definite conclusions can only be reached through more detailed study. Gravel Islands Although not a “high tech” technology, gravel islands have been successfully used in the Beaufort Sea for decades and continue to be viewed as a candidate structure for exploration and/or production in this area of the Alaskan OCS. Since no gravel island structure has been used in the Chukchi Sea, a more detailed assessment would be required to determine feasibility. Due consideration would need to be given to the fact that the nearshore Chukchi Sea ice environment may be more dynamic than the Beaufort Sea. In the nearshore Bering Sea, gravel islands may be subject to higher waves and larger wave loads, which would need to be taken into consideration during detailed assessment. Floating Structures There are only a limited number of floating exploration or production structures that have been used in ice environments. Seasonal exploration can be carried out in the Alaskan OCS using drillships and drilling barges and, in areas without multi-year ice, semi- submersibles or a TLP. However, for exploration, the only location that a floating structure might be capable of staying on station year-round might be the Bering Sea under light ice conditions. A Semi-rigid Floater structure might work year-round under first-year ice conditions but would need to have the ability to disconnect and leave station in the event of potentially higher loads. Floating production systems for the Beaufort Sea, Chukchi Sea and North Bering Sea are not considered to be technically feasible, even with continuous ice management. No floating production structures could be economically designed to stay on station with multi- 01/31/2008 Page iii of xxvi Rev. 0 Arctic Offshore Technology Assessment IMVPA of Exploration and Production Options for Project No. C-0506-15 Cold Regions of the US Outer Continental Shelf year ice loads found in the Beaufort and Chukchi Seas, and possibly northern Bering Sea depending on local ice conditions. Floating systems may have some merit in southern Alaskan OCS areas, however. Subsea Solutions In some cases, there may not be a requirement for a production island or platform offshore. If the wellhead is located in water of sufficient depth, protection from ice would not be necessary. In areas with water depths less than the maximum ice keel depth, glory holes may need to be considered to protect the subsea facilities from ice ridge keels. Improvements in the area of subsea facilities and processing have been made in recent years in the pursuit of resources in harsh and remote environments. As a result of these improvements, fields requiring longer, deeper subsea tiebacks are now becoming much more technically and economically feasible. Gas tiebacks have reached 105 miles (170 km) and oil tiebacks have reached 40 miles (65 km). Subsea facilities can potentially be considered for any development on the Alaskan OCS. However, there are limitations on which technology should be or would need to be considered. Glory holes would only offer protection from gouging keels. Where active ridge building is taking place or there are grounded ridges present, there is the potential for a ridge keel to be pushed into an open glory hole as the ridge keel is being formed. Beyond the zone of active gouging, subsea facilities might be placed directly on the seabed (depending on the ice gouging regime). Pipelines & Flowlines Pipelines have been designed, constructed and are operational in the arctic, but these are in relatively shallow water depths and relatively close to shore. Pushing the limits to developments further offshore in deeper water will require that additional consideration is given to aspects related to design, construction and operation. Some of the main considerations with respect to pipeline design in the arctic are strudel scour, thaw settlement of permafrost, upheaval buckling and ice gouging. It is generally felt that the first three considerations can be designed for on future projects. However, pipeline burial for protection in water depths from approximately 65 to 130 ft (20 to 40 m) will be a challenge given the more severe gouging in these water depths and the fact that the pipeline can likely not be installed from the ice in winter. While trenching from the ice to a 01/31/2008 Page iv of xxvi Rev. 0 Arctic Offshore Technology Assessment IMVPA of Exploration and Production Options for Project No. C-0506-15 Cold Regions of the US Outer Continental Shelf certain water depth has been proven on projects in the nearshore Beaufort Sea, trenching and pipeline installation from floating vessels has not yet been attempted. Export Terminals The technical feasibility of marine terminals in arctic areas has been established through successful experience in a wide range of port facilities. A general review of experience in operation of high-latitude oil and gas marine terminals indicates that existing technology of port structures design and construction is sufficient to support operations in the Alaskan OCS.