Based on experience gained from the handling, running and retrieving of drill pipe for trenching operations Island Offshore’s vessels now provide the capability to drill surface hole for conductor pipe, install the subsea wellhead system and cement the pipe in place. Using the mono hull DP -3 vessels provides a lower cost solution than the use of a drilling rig.
Following rig arrival on location and positioned above the well, it can immediately run the subsea BOP stack and riser system and start drilling operations thus providing lower per well drilling costs. FEED studies have confirmed the suitability of these operations from a monohull vessel subject to specific field conditions.
The vessel provides services for surface hole drilling including:
Pipe racks located on the main deck
- Pipe lifting and handling
- Pipe skidding and pick up system
- False rotary table above the moon pool
- Top drive system can be implemented
- Hydraulic pipe make and break system (iron roughneck)
- Cement mixing and pumping
The top hole drilling system drills surface hole in open water to allow the installation and cementing of 30”/36” conductor pipe and wellhead. Hole for 20”/26” casing can then be drilled and casing and high pressure wellhead landed and cemented.
With the wellhead system in place the rig can proceed to run the subsea BOP system after it is positioned on location and commence drilling operations. This reduces rig time associated with establishing the well and results in lower per well rig costs.
There are certain limitations associated with drilling from a mono hull vessel, and operations can be influenced by issues including drilling depths and casing weights.