Major topics at the 1983 Offshore Technology Conference reflected the increase in developments for drilling activities in the Beaufort Sea.
Following earlier experience using a converted drillship (1974), operators have now engineered and constructed some site-specific structures which take into account the progress made in ice technology.
In like vein, it is essential for our industry that a production system for such environments be studied and designed immediately, in anticipation of rates of return which will recover the high costs of the exploration programmed.
We suggest that a North Sea type marginal/early production system might be called a "seasonal production system" for these frontier areas.
The basis of our presentation is a conceptual loading and transportation system using a tanker and subsea terminal in an arrangement which should favorably reduce operational downtime.
Our concept comprises a fully submerged tanker terminal incorporating the following innovative components:
∗ a single-point subsea mooring, providing unrestricted 360-degree rotation, which could be either of the gravity type or piled to the sea bed.
∗ a combined loading hose and mooring line which remains fully submerged in the stand-by and operating modes.
∗ a submerged tanker loading inlet recessed into the hull of the tanker below the ice cover.
Much has been written about the developments currently taking place in the Beaufort Sea offshore of the MacKenzie delta in Canada. Operations in an Arctic environment were well covered at the 1983 Offshore Technology Conference in Houston, as indicated by the titles of many of the papers presented. A sudden increase in the level of drilling activity in this area is evident, with much emphasis on site-specific designs incorporating the most up-to-date technology available.
A brief review might include the following projects:
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1975 - Drilling in the Arctic zone from a gravel island.
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1976 - Seasonal drilling activities using converted drillships with conventional mooring systems, and ice-reinforced supply vessels.
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1980 - Construction of gravel islands and use of land rigs to increase the length of the drilling season. - Commissioning of Class III Ice Breaker.
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1981 - Use of a moveable concrete drilling caisson ballasted down on to the top of a previously-constructed gravel berm.
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1982 - Conversion of a tanker into a submersible drillship to be ballasted down on to an existing drilling site.
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1983 - Commissioning of a unique circular semisubmersible drilling unit to operate in deeper water and lengthen the drilling season, based on Ice Class 4 design criteria, and supported by new Ice Class 4 supply/anchor handling vessels.
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1984 - Commissioning of a large submersible steel caisson for "all-year-round" drilling, incorporating full ice protection and requiring minimum supply logistics.
The total projected investment in Arctic exploration over the next five years is US$ 2 billion. This encouraging trend towards future production is acknowledged by the industry, and engineering studies for production from the Canadian Arctic have now been accelerated.
We believe that, in similar fashion to the pattern of evolution which occurred in the North Sea, nonconventional systems will be designed to tackle the problems associated with ice coverage.
