Abstract

DeepStar has evaluated new and emerging technologies as applied to the development of a small stand-alone (marginal) field in 10,000 feet of sea water (fsw) Gulf of Mexico conditions. These studies identify viable field development scenarios which improve field economics. Further, the studies identify knowledge gaps requiring further investment before these development systems are ready for field application. This paper describes the evaluation process and uses FPSO development alternatives to illustrate the identification of specific gaps for FPSOs in 10,000 fsw.

Introduction

Deepwater fields like Thunderhorse are currently being developed in water depths approaching 6,000 fsw in the Gulf of Mexico and discoveries have been made in water depths to 10,000 fsw with numerous intermediate water depth discoveries. DeepStar commissioned studies to identify the technical gaps where selected investments today will enable future development of these smaller deepwater stand-alone fields tomorrow.

The DeepStar study is conducted similar to an early commercial field development concept selection and trade-off study using selection criteria including high level economics. A life-cycle economic model is prepared for each field development alternative considered viable by the technical committee. Where technology is extended or new technology is assumed available, an estimated commercial cost is used based on practical input from the DeepStar Participants. Due to this "realistic" input received from the Industry, no additional mark-up for new technology risk or large first user costs are applied. This yields a mature concept comparison where the field development alternatives may be compared on an equivalent basis. The most promising development scenarios can then be identified.

Evaluation criteria included:

  • Projected economic performance (Internal Rate of Return) for a qualified development system

  • Schedule to "project qualify"; and

  • Cost to "project qualify" the necessary technologies to enable this field development system.

The DeepStar studies have evaluated four surface facility scenarios for the example field. These are:

  • Semisubmersible - provides lowest motion solution.

  • SPAR - features low motion and dry trees.

  • TLP - requires new tendon technologies for 10,000 fsw; and

  • FPSOs - with a gas export pipeline and oil shuttle tanker.

Each scenario has been evaluated to the same level and consistent basis both technically and commercially. To illustrate the process and some of the findings, this paper will focus discussion on FPSOs for 10,000 fsw GOM marginal field developments.

When extending these surface facilities to 10,000 fsw, critical aspects that need to be fully understood include:

  • The station-keeping method,

  • The riser system,

  • The surface facility, and

  • How these all items interrelate and operate as integrated units through all phases of operation (design, construction, installation, normal production, storm conditions, etc.)

This understanding has to be further communicated to the regulatory and classification agencies so appropriate approvals to develop and operate the field may be obtained in a timely manner.

There are at least two viable FPSO arrangements which were conceptually considered and these are discussed later in the paper. These are:

  • Permanently moored weathervaning FPSOs.

  • Dynamically Positioned FPSOs.

Keywords:
disconnect, operation, hermit field, application, upstream oil & gas, requirement, hull, stiffness, storage, dp fpso
Subjects:
Pipelines, Flowlines and Risers, Offshore Facilities and Subsea Systems, Risers
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2005. Offshore Technology Conference
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