DOT 2010: Selecting Floating Production Platforms for Developing Deepwater Gulf of Mexico Fields

Selecting a floating platform for a deepwater development in the Gulf of Mexico is an important and challenging activity in the select phase of the field development planning process, according to a report presented by Richard D'Souza and Shiladitya Basu of Granherne Americas at the Deep Offshore Technology Conference and Exhibition in Houston.

Offshore staff

HOUSTON -- Selecting a floating platform for a deepwater development in the Gulf of Mexico is an important and challenging activity in the select phase of the field development planning process, according to a report presented by Richard D'Souza and Shiladitya Basu of Granherne Americas at the Deep Offshore Technology Conference and Exhibition in Houston. Deepwater developments are capital intensive and the financial consequence of poor selection can be severe. In the select phase, an operator has to choose from a catalogue of platform types (spar, TLP, semisubmersible, FPSO) and functionalities (dry or wet trees; drilling workover or production). The challenge is to select the platform type and functions that fits the reservoir depletion plan (well count, placement, intervention, production profile) and site characteristics (water depth, metocean conditions, seabed topography) while satisfying commercial and strategic objectives.

Successful selection requires a systems approach that considers all surface facility components including subsea flowlines, risers, export systems, flow assurance, and operations. It has to be fully integrated with and keep pace with maturation of subsurface development.

Defining key drivers and performance indicators for the field development is crucial to successful system selection. Financial value frequently is the primary driver. The development option that proves the best financial value, with due consideration of associated risks, most always prevails. A broader set of strategic or philosophical indicators also must be established, should financial metrics not provide a clear differentiation. These include:

• Adaptability to manage reservoir uncertainty
• Flexibility for expansion (hub facility)
• Standardization philosophy.

Establishing basic platform functions must occur early during screening. These include choices such as wet or dry tree followed by the drilling, workover ,or production capacities. The functions have a impact platform screening and selection and are driven principally by the size, geometry and complexity of the reservoir(s).

Floating platform selection is driven basically by the reservoir. Shape, size, complexity, rock, and fluid properties determines well count, well placement, production profiles, and recoverable reserves. These parameters, in turn, drive early decisions regarding wet or dry tree development, drilling or workover requirements, or the need for boosting. Water depth is next in the selection hierarchy with TLPs dropping out beyond 5,000 ft (1,524 m) depths.

A floating platform selection decision trees for small, medium, and large reservoirs was presented. Depending on shape and size of reservoir and water depth at the site, the decision tree enables rapid screening of platform options and functions to match the subsurface drivers. The decision tree is validated by listing each of the floating platforms sanctioned in the GoM in its appropriate branch. Insights into the decision making process underpinning the selection of floating platforms for several major GoM deepwater field developments were illustrated.

02/02/2010

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