Abstract

This paper describes the results of the feasibility study of an arcticoffshore platform concept sponsored by ConocoPhillips. This concept consists ofa Conical Piled Monopod (CPM) platform, shown in Figure 1, assisted by an IceWorthy Jack-up rig, Gemini, to drill development wells in Multi Year iceconditions as illustrated in Figures 2 and 3. The Gemini design is beingjointly developed by ConocoPhillips and Keppel Offshore and Marine TechnologyCentre Pte Ltd based in Houston. Gemini is equipped with two drill rigsthat can simultaneously or individually cantilever above the well slots locatedon the deck of the CPM. The key benefit of Gemini lies in extending thedrilling season from a few months during ice free season to several monthsbeyond the ice free period.

The study was carried out at Granherne Limited under ConocoPhillips'supervision between March 2010 and February 2011. A topsides operatingload of 5,000 tonnes was assumed, instead of 70,000 tonnes (or more)corresponding to a two drill rig stand alone drilling and production CPM. Thefeasibility of a stand alone drilling and production CPM was presented inanother paper at Icetech12 in September 2012.

The study concludes that a Gemini assisted CPM is feasible for iceconditions in the Canadian Beaufort Sea. The ice loads were calculated, in consultation with Ken Croasdale, a well known specialist in this discipline. Ice conditions assumed in this study were in accordance with ISO-19906, namely,12m thick level ice and a very rare 25m thick ice island event. No icemanagement was assumed. A Gemini assisted CPM offers a much lighter platformcompared to a standalone CPM or Gravity Based Structure.

ConocoPhillips has a patent pending on the CPM. ConocoPhillips andKeppel Offshore have patent(s) pending on the Ice Worthy Jack Up drilling rig, Gemini.

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