When a jackup platform drills wells in locations that may be subject to sea ice, the risers need to be protected from forces due to impact with the sea ice. The existing options for doing so include:
1. Drilling with the riser unprotected;
2. Providing coatings to the riser to protect against corrosion, fouling etc, but without protection from large ice or ship impacts;
3. Drilling through a minimal wellhead platform which supports the wellhead and conductor but is not designed to provide protection from large forces, for example ice impacts;
4. Drilling through a substantial protection structure such as a conical piled monopod (CPM); and
5. Drilling from a large combined drilling and production platform.
Options 3, 4 and 5 are all permanent structures and cannot be easily removed for reuse when the drilling activity is complete and not economical for exploration drilling where only one well is drilled at a location. As they are permanent they must also be designed for the worst possible design conditions as they cannot be removed if unusually large forces are expected.