Ursa TLP Topside-Module Installation and Hull-Deck-Rig Integration
Authors: Gottung Paul W. , Digre Kris A. , Hughson Robert A. , Lindsay Mark S. , Schipper Hans 
Published: October 2008

This paper discusses the planning and execution of the URSA topsides module and drilling rig installation and the integration of hull, topsides deck and rig systems. This work included module and rig transportation and setting, topsides structural integration, Tension Leg Platform (TLP) safety, utilities and process facilities hookup and systems commissioning. The original execution plans called for a Gulf of Mexico Mississippi Canyon (MC-809) on-site module setting onto a tendoned hull and hook-up of the modules after hull tendon installation. The four-month delay of the TLP project installation from June 1998 to October 1998 necessitated a radical change in execution plans if the original first oil targets were to have a chance of being met. In March 1998, the decision was made to set the modules and perform a partial integration at a nearshore site in Curacao, the Netherlands Antilles. The TLP hull would then make a manned 25+ day tow to the Gulf of Mexico for tendon installation, followed by completion of the TLP production facilities hook-up and commissioning.

The Project Team worked very closely with the Contractor, Heerema, to plan the additional workscope, establish the Curacao shorebase site and commence module installation and integration by July 1998, execute hull-deck-rig integration during September and October, leading to a manned tow to the GOM during November, 1998.

Introduction

The Ursa TLP's primary structural design of (6) deck modules supported from the hull by an upper column frame (UCF) was a third generation design of the tension leg platform. The intent (and result) of the design was to provide cost and schedule benefits through reduced hull/topsides structural and piping interconnection. The deck module lift and set required the use of the maximum capabilities of Heerema Marine Contractors' (HMC) Semi Submersible Crane Vessel (SSCV) Balder. The decision to rely on a marine vessel based crane in lieu of a purpose built dockside lifting device, had unexpected risk, schedule, planning and cost impacts late in the TLP fabrication cycle. The planned summer 1998 Balder SSCV access to the TLP installation site was blocked by a (4) month delay in the pre-drilling program. This required a significant late project scope change to mitigate the impact on both the risk and cost of installing the TLP and also to reduce delays in Ursa's first hydrocarbon production.

Why install modules and partially integrate in Curacao?

The original plan for TLP installation was to tendon the hull at Mississippi Canyon 809, install the modules and perform the integration of modules and hull totally at the offshore site. The timing of this work was estimated as May-June, 1998. Prior to the offshore installation, a semi-submersible drilling rig was performing pre-drill operations. Difficulties with the pre-drill program caused slippage in the TLP installation schedule such that offshore mobilization would be delayed to November 1998.

Curacao was initially selected as a location to store the Ursahull, if needed, on its voyage from the Belleli fabrication yard in Taranto, Italy, to the Gulf of Mexico installation site. This could be necessary because of the lengthened pre-drill operations in the Gulf of Mexico. SDDSI's offshore general contractor, HMC, had previous experience in Curacao as their SSCV, the Balder, had been there for routine maintenance. Thus Curacao, being in proximity to the tow route, became a favored storage site for the hull.