Kizomba A and B: Installation Overview
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 17941, "Kizomba A and B: Installation Overview," by J.B. Bates, G.O. Gernon, and M.D.A. Gillette, ExxonMobil, prepared for the 2006 Offshore Technology Conference, Houston, 1-4 May.

Completing the Kizomba A and B projects with world-class schedule performance was a rare opportunity that yielded outstanding results. These two projects, within 7 miles of each other in Block 15 offshore Angola, were brought on line 11 months apart. Kizomba B built upon experience gained from Kizomba A to improve performance from contract award to the start of production. Continuous implementation of lessons learned and repeat use of Kizomba A prime contractors and ExxonMobil personnel resulted in time savings and installation-activities flexibility that ultimately contributed to an improved first-oil date for Kizomba B.

Introduction

Kizomba A and B shared the same field-development concept that included subsea drill centers and a close-moored surface wellhead platform (SWHP) tied back to a spread-moored floating production, storage, and offloading vessel (FPSO). The FPSO and SWHP are connected by flexible fluid-transfer lines. Oil is offloaded from the FPSO by use of a buoy-based oil-offloading system (OOS) composed of one oil-offloading buoy (OOB), its mooring system, and two 20-in. rigid steel-pipe oil-offloading lines (OOLs). Figs. 1 and 2 illustrate the similar Kizomba A and B field-development concepts.

Execution Strategy

Execution strategy, which was consistent between the two projects, specified four engineering, procurement, and construction (EPC) subprojects awarded to four prime contractors, and separate contracts for a mobile offshore drilling unit (MODU) and a main instrumentation and controls contractor.

Tieback Subprojects

Unlike the other Kizomba B subprojects, the tiebacks-subproject deliverables and installation activities differed significantly from those of Kizomba A. Table 1 in the full-length paper describes the work scope of both subprojects. The differences necessitated changes in established procedures, some new procedures, and modified installation equipment in certain instances.

Most components of the Kizomba B tiebacks subproject required significant changes from Kizomba A, including the following.The SWHP tieback system had different fluid and flow requirements, which necessitated different flexible pipes and a different supplier.The subsea tieback system required longer flowlines, and addition of production flowlines from the remote drill centers to the FPSO required insulated pipe-in-pipe (PIP) flowlines and risers and insulated jumpers.Subsea hardware was significantly different.The FPSO mooring system had fewer lines and different installation procedures.

Personnel

One aspect of the tiebacks subproject that closely followed the "Design One, Build-Multiple" philosophy was the effort to retain the same design, procurement, and installation personnel from Kizomba A to B from both operator and contractor. The same offshore organization accompanied the main installation vessel, the field-development ship (FDS), for both Kizomba A and B. However, the overall project execution timelines overlapped for several months, causing the contractor to use two separate lead-project management staffs to direct each project, ensuring that priori-ties for each were managed effectively.