Fractal column offset tension leg platform (COTLP)

Abstract

A Fractal Column Offset Tension Leg Platform (COTLP) consists of a semi-submersible hull type, tension moored to the seabed. The Fractal COTLP advances the state of technology by utilizing fractal arrangements of repeated, similar structural units, consisting of continuous pontoons and intermittent columns, to provide better construction, operation, stability, payload and service life advantages over existing Tension Leg Platform (TLP) types. Varying, fractal-like geometric arrangements also provide for sizing and configuration advantages and the capability to work in greater water depths than existing TLP technology. Furthermore, fractal arrangements and inter-column spacing can also be optimized to minimize platform hydrodynamic response to waves, thereby reducing mooring and hydrodynamic loads and consequently achieving an optimal and safer platform structure with a longer fatigue life.

Description

REFERENCES TO RELATED PATENTS[0001]3,577,946May 1971Horton3,919,957November 1975Ray et al.3,982,492September 1976Steddum4,436,050March 1984Liden4,498,142February 1985Liden4,844,659July 1989Hunter et al.5,147,148September 1992White et al.5,330,293July 1994White et al.5,421,676June 1995Wybro et al.5,964,550October 1999Blandford et al.6,190,089February 2001Bennett, Jr. et al.6,447,208September 2002Huang et al.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]No Federal sponsorship, research support or assistance of any kind was provided, obtained or utilized in the development of the invention and technology described herein.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]Floating production facilities for deepwater oil and gas production include floating production and storage / offloading vessels (FPSO), semi-submersibles, spars and tension leg platforms (TLP). Each facility has inherent advantages and limitations in water depth, ability to host proce...

AI Technical Summary

Benefits of technology

[0011]This specification describes a Column Offset Tension Leg Platform (COTLP), a new type of Tension Leg Platform (TLP). A COTLP is a tension leg platform that is arranged in a fractal, spirally symmetric pattern and that consists of continuous structural pontoons onto which columns are mounted and tendons are attached. There are several advantages to a COTLP. A COTLP affords significant design and construction advantages over existing TLP types. The COTLP incorporates better hydrodynamic, mooring, systems integration and payload characteristics. A COTLP advances technology to operate safely in water depths exceeding current TLP limits. As a consequence, a COTLP will be more cost effective to design, build, install and maintain and a COTLP can be installed in greater water depths than existing TLPs.

Problems solved by technology

There are some structural inefficiencies and design and operating limits inherent in each existing TLP design type.

This results in high stress loads arising in way of the column and pontoon connections.

Difficulty with existing TLP designs arises in way of the tendon porch connections to the TLP.

These shortcomings are difficult to increase fabrication complexity and associated cost.

Another problem that arises with existing TLP technologies pertains to locating the tendon porches as far apart as possible in order to maximize mooring spread.

On existing TLPs in order to maximize the mooring spread one invariably maximizes the inter-column spacing which results in greater topsides steel and higher deadweights, and therefore reduced payloads.

Maximizing the mooring spread for mini-TLPs requires longer tendon arms and extensions which bring about additional structural and stability problems for this type of platform.

Existing TLP designs are limited by water depth in which they can be economically installed and operate: As water depth increases, tendon length and size, and thus weight (deadweight) increases quickly and a functional limit of water depth (decreasing payload) is soon realized.

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