Offshore buoyant drilling, production, storage and offloading structure

• US 8,251,003 B2
• Filed: 10/28/2010
• Issued: 08/28/2012
• Est. Priority Date: 11/08/2009
• Status: Active Grant

• Current Assignee: Jurong Shipyard Pte. Limited
• Original Assignee: SSP Technologies, Inc.
• Inventors: Vandenworm, Nicolaas J.
• Primary Examiner(s): AVILA, STEPHEN P
• Application Number:
  US12/914,709
• Publication Number:
  US 20110107951A1
• Time in Patent Office: 670 Days
• Field of Search: 114/230.2
• US Class Current: 114/230.2
• CPC Class Codes: B63B 1/041 with disk-shaped hull
• CPC Class Codes: B63B 2001/044 with a small waterline area compared to total displacement, e.g. of semi-submersible type
• CPC Class Codes: B63B 2035/446 for converting wind energy into electric energy
• CPC Class Codes: B63B 2039/067 effecting motion dampening by means of fixed or movable resistance bodies, e.g. by bilge keels
• CPC Class Codes: B63B 22/021 and for transferring fluids, e.g. liquids container type buoys having means to selectively release contents, not adapted for mooring a vessel B63B22/26
• CPC Class Codes: B63B 2211/06 Operation in ice-infested waters
• CPC Class Codes: B63B 2241/06 circular
• CPC Class Codes: B63B 35/44 Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices construction methods for floating offshore platforms B63B75/00
• CPC Class Codes: B63B 35/4413 Floating drilling platforms, e.g. carrying water-oil separating devices
• CPC Class Codes: B63B 39/00 Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude for amphibious vehicles B60F3/0038

Abstract

An offshore structure having a vertically symmetric hull, an upper vertical wall, an upper inwardly-tapered wall disposed below the upper vertical wall, a lower outwardly-tapered wall disposed below the upper sloped wall, and a lower vertical wall disposed below the lower sloped wall. The upper and lower sloped walls produce significant heave damping in response to heavy wave action. A heavy slurry of hematite and water ballast is added to the lower and outermost portions of the hull to lower the center of gravity below the center of buoyancy. The offshore structure provides one or more movable hawser connections that allow a tanker vessel to moor directly to the offshore structure during offloading rather than mooring to a separate buoy at some distance from the offshore storage structure. The movable hawser connection includes an arcuate rail with a movable trolley that provides a hawser connection point that allows vessel weathervaning.

Claims

1. A buoyant structure (10) for petroleum drilling, production, storage and offloading, comprising:

a hull (12) defining a vertical axis (100) whereby said hull (12) is characterized by circular horizontal cross-sections at all elevations, said hull characterized by an upper cylindrical portion (12b), an upper frustoconical portion (12c) directly connected to the bottom of said upper cylindrical portion (12b) so as to have inward-sloping walls at a first angle (α

) with respect to said vertical axis (100) between 10 and 15 degrees, a lower frustoconical portion (12d) disposed below said upper frustoconical portion (12c) and having outward-sloping walls at a second angle (γ

) with respect to said vertical axis (100) between 55 and 65 degrees, a lower cylindrical portion (12e) directly connected to the bottom of said lower frustoconical portion (12d);

a planar horizontal keel (12f) defining a lower hull diameter D₁, and a generally horizontal main deck (12a);

wherein said upper vertical wall section (12b) defines an upper hull diameter (D₂), said upper tapered wall section (12c) abuts said lower tapered wall section (12d) at a hull neck diameter (D₃), the height (h) of said hull (12), defined from said keel (12f) to said main deck (12a), is less than said hull neck diameter (D₃), said lower hull diameter (D₁) is the largest diameter of said hull, said hull neck diameter (D₃) is the smallest diameter (D₃) of said hull, said hull neck diameter (D₃) is between 75 and 90 percent of said upper hull diameter (D₂), and said lower hull diameter (D₁) is between 115 and 130 percent of said upper hull diameter (D₂); and

wherein said structure (10) defines a center of gravity and a center of buoyancy, said center of gravity located below said center of buoyancy.