Ice worthy jack-up drilling unit with gas agitated ice prevention

• US 8,956,081 B2
• Filed: 10/21/2011
• Issued: 02/17/2015
• Est. Priority Date: 10/21/2010
• Status: Expired due to Fees

• Current Assignee: Conocophillips Company (ConocoPhillips)
• Original Assignee: Conocophillips Company (ConocoPhillips)
• Inventors: Noble, Peter G., Shafer, Randall S., Berta, Dominique P.
• Primary Examiner(s): Pinnock, Tara M.
• Application Number:
  US13/279,062
• Publication Number:
  US 20120128431A1
• Time in Patent Office: 1,215 Days
• Field of Search: 405196-199, 405/203, 405/211, 405/217, 405/224
• US Class Current: 405/217
• CPC Class Codes: B63B 2211/06 Operation in ice-infested waters
• CPC Class Codes: E02B 1/003 Mechanically induced gas or liquid streams in seas, lakes or water-courses for forming weirs or breakwaters; making or keeping water surfaces free from ice, aerating or circulating water, e.g. screens of air-bubbles against sludge formation or salt water entry, pump-assisted water circulation moving sediments E02B3/023; for ice breakers B63B35/08; aerating or circulating water in fish-tanks A01K63/042; purification of waste water with addition of air C02F; distributing gases in liquids in general B01F23/20
• CPC Class Codes: E02B 17/0021 against ice-loads
• CPC Class Codes: E02B 17/021 with relative movement between supporting construction and platform
• CPC Class Codes: E02B 2017/0039 Methods for placing the offshore structure
• CPC Class Codes: E02B 2017/006 with lattice style supporting legs
• CPC Class Codes: E02B 2017/0082 Spudcans, skirts or extended feet
• CPC Class Codes: E21B 7/008 Drilling ice or a formation covered by ice

Abstract

An ice worthy jack-up rig that may extend the drilling season in shallow water off shore Arctic or ice prone locations. The rig would work like a conventional jack-up rig while in open water with the hull jacked up out of the water. However, in the event of ice conditions, the legs are held in place by cans embedded in the sea floor to resist lateral movement of the rig and the hull is lowered into the water into an ice defensive configuration. The hull is specifically shaped with an ice-bending surface to bend and break up ice that comes in contact with the hull while in the ice defensive configuration.

Claims

1. An ice worthy jack up rig for drilling for hydrocarbons in potential ice conditions in offshore areas comprising:

a flotation hull having a relatively flat deck at the upper portion thereof and an ice bending shape along the lower portion thereof and extending downwardly and inwardly around the periphery of the hull where the ice bending shape extends from an area of the hull near the level of the deck and extends downwardly near the bottom of the hull;

an ice deflecting portion extending around the perimeter of the bottom of the hull to direct ice around the hull and not under the hull;

at least three legs that are positioned within the perimeter of the bottom of the flotation hull wherein the legs are arranged to be lifted up off the seafloor so that the rig may be towed through shallow water and also extend to the sea floor and extend further to lift the hull partially or fully out of the water;

a jack up device associated with each leg to both lift the leg from the sea bottom so that the ice worthy jack up rig may float by the buoyancy of the hull and push the legs down to the seafloor and push the hull partially up and out of the water when ice floes threaten the rig and fully out of the water when ice is not present; and

a gas agitation system including holes in seafloor engaging spud cans at bottom ends of the legs for releasing bubbles through the holes to agitate the water near the legs and reduce issues with ice near the legs and prevents ice from forming on the legs.

2. The ice worthy jack up rig according to claim 1, further including an anchoring mechanism associated with a foot of each leg to provide additional resistance to the forces an ice floe may impose on the rig.

3. The ice worthy jack up rig according to claim 1, wherein the ice bending surface is slanted upwardly and outwardly from a smaller dimension neckline to a larger dimension shoulder.

4. The ice worthy jack up rig according to claim 1, wherein the ice bending surface extends vertically at least 8 to 10 or more meters.

5. The ice worthy jack up rig according to claim 4, wherein the angle of the ice bending surface is in the range of 30 to 60 degrees from the vertical.

6. The ice worthy jack up rig according to claim 1, wherein the ice bending surface comprises a plurality of relatively flat, sloped, segments extending around the periphery of the rig.