The extension covers use of an equipment package similar to an MPD and/or underbalanced drilling operation (UBD) through the lower part of the Shetland caprock and the underlying Drake formation.
The Shetland formation has previously been drilled in near balance/underbalance in C-05 A, while the Drake formation has not previously been drilled with such technology, and is thus considered to be a valuable contribution to the qualification process.
The Drake formation is an impermeable clay deposit, and there are no plans to produce well fluids from the well during this activity.
This option will be used for C-09 A, if the pore and fracture pressure gradients in the well preclude the use of conventional overbalance drilling.
The necessary connections to separators, process plants and other equipment on the facility are planned, in the event of full UBD activity.
Statoil's application includes a description of equipment and methods to be used, as well as which updated assessments, analyses and training measures have been implemented for the planned operations.
In its application, the company concludes that the drilling activity can be implemented within the established safety framework.
Recent risk analyses show that a reduction in risk can be achieved through the use of selected MPD equipment as compared with conventional overbalance drilling on GFC.
Contact person i the Petroleum Safety Authority