Subsea Xmas Tree and Completion Operations on Two Different Subsea Providers with a Single Rig Using One Common IWOCS System

Abstract

Abstract Offshore Congo West Africa, one of the subsea field developments has been installed with subsea production equipment designed and manufactured by two different subsea equipment suppliers. Therefore, it is a major challenge to be able to perform subsea intervention and installation with just one drilling rig being available on this subsea development as the subsea equipment from different subsea equipment suppliers is not design compatible. The conventional approach would be to change out the topside installation and intervention equipment from one manufacturer to that of the other on the rig. As this solution is far too expensive and time consuming, a need for one universal subsea installation and intervention system became an operational requirement. This paper explains how one operator along with two subsea production equipment suppliers were able to design, manufacture and implement one universal drilling system refered to as –IDIMS (Interface for Dual Intervention Mode System). IDIMS increases the operational response while lowering the intervention cost on this field. Indeed IDIMS allows one single rig to intervene, drill and complete with two different subsea production equipment suppliers at a lower cost and with a shorter lead-time, which is a first in the oil industry. For operators, IDIMS XT and TH modes represent a major innovation to reduce costs and drilling times in all subsidiaries with mature submarine fields equipped with different subsea production systems and equipment. Over three years, this innovation allowed 107 MUSD of savings on this field. The IDIMS concept could be reproduced and developed to intervene and drill on other subsea field developments with even more than two subsea production equipment suppliers. A single rig would then be able to operate on all of the subsea wellheads, tubing hangers, subsea XT installed/to be installed in one area, significantly reducing project development costs.