Page 39: of Offshore Engineer Magazine (Jun/Jul 2014)

38 40

(DES) sits on skid beams that

EPIC run in the North South direc- tion to allow the coiled tubing (CT) to be run underneath the

Substructure.

• The DES substructure has a clear height of 13m and the main BOP is placed below the upper deck to allow enough clear space for a stand-alone coiled tubing tower to operate independently without interfer- ing with the drilling operations.

The drilling riser system • has been designed to jump from one well to another without being pulled out of the water.

The drilling riser is hung off at the mezzanine deck in a slot

Hutton TLP legs–the ? rst TLP installed–at Scotland’s Cromarty Firth, post ? eld decommissioning. with a skidding system and is only disconnected from the well- and supplied by a tender vessel. has been developed in two phases. In head at the seabed when moving to the

When the surface wellhead platform 2004, Doris Engineering performed a next target.

with dry trees shows an advantage over conceptual study of a TLWP with tender These innovations combined can pro- the subsea trees then there is a choice assisted drilling for the Moho Bilondo vide a signi? cant saving in the drilling between three concepts; the deep draft development that was compared to a durations with an associated saving on semi, the SPAR and the TLP. In West solution with two subsea drill centers the overall drilling costs.

Africa, the long period swells have an tied back directly to the FPU barge. On In the benign environmental conditions adverse effect on the dynamic behavior of this occasion, the subsea solution was found in West Africa and southeast Asia, the deep draft ? oaters, like the semi and selected and the FPU was installed and the TLWP with tender assisted drilling the SPAR, and the TLP becomes an obvi- brought on-stream in 2008. Nevertheless, (TAD) has been found to be an interest- ous choice. The only drawback with a this early work proved the feasibil- ing solution in deep waters. It is a robust

TLP is that it is designed for a given pay- ity of a number of key technical issues concept when dry trees are required to load, which implies a good evaluation of and laid the foundations for the future improve reservoir management and facili- the weight from the start, including any development. tate well intervention operations and with future modi? cations, and accurate weight In 2011, for the Moho Nord develop- the recent innovations in the drilling and control throughout the project. ment, Total again included the TLWP well intervention systems it may become

Doris Engineering has been develop- in the concept screening process when the cost effective solution for other similar ing the TLWP concept for more than two looking at how to produce the Albian developments in the future. decades, analyzing pros and cons, adapt- reservoirs, which are deep formations ing technology, and proposing innovative more than 3000m below mudline. The Jérôme Iacovella solutions for the particular West African complexity of these reservoirs imposed a joined Doris environmental conditions found in the high level of reservoir management with Engineering in 2000

Gulf of Guinea. a need for frequent well intervention. It as a naval architect.

Exxon Mobil showed the way when was this requirement that led the project He is now heading they installed the ? rst two TLPs in team to select the TLWP concept, with the naval architec-

West Africa. The Kizomba A TLWP was dry trees that would allow drilling and ture and marine installed in 2004, on Angola’s block coiled tubing operations to be performed operations depart- 15, 300m from the host FPSO. The key simultaneously. ment. He has been particularly involved parameter for this concept develop- Doris Engineering has been involved in the development of Moho Nord TLP ment selection seemed to be the need to with this project since the conceptual and project for Total. develop the early-Aptian reservoir and the pre-project studies and subsequently the requirement for careful reservoir as the engineering subcontractor of Pauline Beraud management with frequent well inter- Hyundai Heavy Industries, which as the joined Doris ventions. The TLWP hosted the produc- successful bidder of the compensated call Engineering as a tion dry trees and subsea wells were for tender (CCFT). During these engineer- naval architect in dedicated to gas and water injection. The ing studies, the following new features 2006. For more than same development scheme was retained have been introduced by Total to make the three years she has for Kizomba B, which followed in 2005. Moho Nord a unique TLWP concept: been involved in the •

Semi tender assisted drilling (STAD) development of Moho

The Moho Bilondo development unit is positioned on the east side of Nord TLP project. She holds and engineer-

The Moho Bilondo ? eld, offshore Congo, the TLP and the derrick equipment set ing degree from ENSTA Paris Tech.

oedigital.com June 2014 | OE 41 040_OE0614_EPIC2_Doris.indd 41 5/23/14 11:23 AM