Ice worthy jack-up drilling unit

Abstract

The invention relates to an ice worthy jack-up rig that may extend the drilling season in shallow water off shore Arctic or ice prone locations. The inventive 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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Application Ser. No. 61 / 405,497 filed Oct. 21, 2010, entitled “Ice Worthy Jack-Up Drilling Unit,” which is incorporated herein in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]None.FIELD OF THE INVENTION[0003]This invention relates to mobile offshore drilling units, often called “jack-up” drilling units or rigs that are used in shallow water, typically less than 400 feet, for drilling for hydrocarbons.BACKGROUND OF THE INVENTION[0004]In the never-ending search for hydrocarbons, many oil and gas reservoirs have been discovered over the last one hundred and fifty years. Many technologies have been developed to find new reservoirs and resources and most areas of the world have been scoured looking for new discoveries. Few expect that any large, undiscovered resources remain to be found near popul...

AI Technical Summary

Benefits of technology

[0010]The invention more particularly relates to an ice worthy jack up rig for drilling for hydrocarbons in potential ice conditions in offshore areas including a flotation hull having a relatively flat deck at the upper portion thereof. The flotation hull further includes an ice bending shape along the lower portion thereof and extending 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 along with 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. The rig includes at least three legs that are positioned within the perimeter of the bottom of the 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 is 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 w

Problems solved by technology

Few expect that any large, undiscovered resources remain to be found near populated areas and in places that would be easily accessed.

Instead, new large reserves are being found in more challenging and difficult to reach areas.

However, the Arctic is remote and cold where ice on the water creates considerable challenges for prospecting for and producing hydrocarbons.

Over the years, it has generally been regarded that six unprofitable wells must be drilled for every profitable well.

However, in the Arctic, little, if anything, is inexpensive.

Even during the few weeks of open water, ice floes present a significant hazard to jack-up drilling rigs where the drilling rig is on location and legs of the jack-up drilling rig are exposed and quite vulnerable to damage.

However, the legs of a jack-up provide little defense against ice floe collisions and an ice floe of any notable size is capable of causing structural damage to one or more legs and / or pushing the rig off location.

If this type of event were to happen before the drilling operations were suspended and the well was suitably secured, a hydrocarbon leak would possibly occur.

This type of risk is completely unacceptable in the oil and gas industry, to the regulators and to the public.

These gravity based structures are very large and very expensive, but are built to withstand the ice forces year around.

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