Abstract

Installation of a Tension Leg Platform comprises distinct phases, all of which can provide special challenges when considering locating a TLP in a frontier area, for example in offshore Brazil. The ways these challenges have been addressed on previous TLPs installed in previously undeveloped areas, such as West Africa, Indonesia, and even portions of the Gulf of Mexico, can be used in planning installations in new areas such as offshore Brazil. This paper provides an overview of these challenges, and suggests ways in which they could be solved for application in offshore Brazil.

The specific phases of TLP installation which are discussed in this paper are fabrication of the TLP tendons, transport and installation of the tendons, delivery of the TLP hull to the installation site, hook up of the TLP hull to the tendons, and completion of the TLP installation. These phases are interrelated; a successful TLP installation relies on proper sequencing and coordination of them all. This paper gives insight into how this can be achieved in a reliable and efficient manner, again drawing from proven industry success as well as those projects that provided valuable lessons learned.

While there are many options to develop fields in frontier areas, use of a TLP may sometimes be ruled out due to concerns about installation. This paper helps establish confidence that TLP installation is indeed a viable option that should be considered in offshore Brazil.

Introduction

Venturing offshore with oil and gas production facilities in frontier regions of the world has typically taken advantage of simulating onshore working environments. First offshore installations have typically been bottom founded structures, in relatively shallow water, often within site of the shore. It was relatively easy to install equipment on these platforms that a readily available, local work force would feel comfortable operating. The stability of the bottom founder structures provided a working environment quite similar to that found on shore, with the obvious exceptions of limited surrounding space.

As the push continued to develop resources even further offshore, floating options as the base for operations were required. The attractiveness of a TLP for use in such frontier areas is that its outward appearance may still closely resemble that of bottom founded structures, and its motion characteristics will not represent a quantum step in adjustment for the work force. However, while the outward appearance may be similar, the structure itself - the components from which it is made and the means by which they are installed - have significant differences that may represent challenges in developing frontier areas, such as offshore Brazil. Developments in other similar areas, specifically Southeast Asia and West Africa, have shown ways in which these challenges can be solved.

The critical components of a TLP are: the topsides (for example, drilling, production, accommodations, etc.), the hull, the tendon system and the foundation. The only one of these components that has similarity to the " stepping stone" facilities developed prior to the offshore installation is the topsides. All the remaining components represent challenges from perspectives of construction and fabrication, as well as installation. The form of the challenges is that they represent new or different types of materials as well that they require different strategies and methodologies for installation. This paper will touch briefly on the materials challenges, and then focus on the details of installation.

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