US4048943A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arctic caisson
Assignee: ExxonMobil Upstream Research Co
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Filing: 1976-05-27
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Granted: 1977-09-20
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Expires: 1996-05-27
Abstract
Abstract An offshore structure, adapted for operation in an ice infested arctic environment, includes a floating caisson that can be actively heaved in the water to break ice. The caisson comprises a radially tapered upper portion, preferably conically shaped. Means for vertically moving the caisson are provided so that the upper portion of the caisson can obliquely contact ice sheets and other ice masses with sufficient dynamic force to pierce and break the ice. A plurality of mooring lines anchored to the sea floor are attached to the caisson to secure its position in the water.
Inventors
- 👤 Ben G. Gerwick, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:49
CPC Classifications
B; B63; B63B; B63B35/00; B63B35/44; B63B35/4413; B63B35/08; B63B1/00; B63B1/02; B63B1/04; B63B2001/044; B63B2211/00; B63B2211/06
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
82 words
An offshore structure which is adapted for operation in an arctic sea containing floating ice masses comprising: a floating caisson, said caisson having a radially downwardly tapered upper ice-breaking portion; a plurality of mooring lines secured at a first end to said caisson and at a second end to the sea floor; and means for vertically moving said caisson a sufficient distance and with sufficient dynamic force so that said upper portion of said caisson obliquely contacts and breaks said ice masses.
Claim 2
Dependent Claim
82 words
An offshore structure which is adapted for operation in an arctic sea containing floating ice masses comprising: a floating caisson, said caisson having a radially downwardly tapered upper ice-breaking portion; a plurality of mooring lines secured at a first end to said caisson and at a second end to the sea floor; and means for vertically moving said caisson a sufficient distance and with sufficient dynamic force so that said upper portion of said caisson obliquely contacts and breaks said ice masses.
Claim 3
Dependent Claim
27 words
The offshore structure of claim 1 wherein a drilling platform is positioned on top of said caisson, said drilling platform being equipped to conduct earth drilling operations.
Claim 4
Dependent Claim
23 words
The offshore structure of claim 1 wherein said upper portion tapers at an angle of between about 30° and 60° from the vertical.
Claim 5
Dependent Claim
23 words
The offshore structure of claim 1 wherein said upper portion tapers at an angle of between about 40° and 50° from the vertical.
Claim 6
Dependent Claim
55 words
The offshore structure of claim 1 wherein said upper portion of said caisson is in the shape of a truncated cone which is maintained substantially above the sea surface and wherein said means for vertically moving said caisson permits said upper portion to move in a downward direction to strike and break said ice masses.
Claim 7
Dependent Claim
56 words
The offshore structure of claim 1 wherein said upper portion of said caisson is in the shape of an inverted truncated cone which is maintained substantially below the sea surface and wherein said means for vertically moving said caisson permits said upper portion to move in an upward direction to strike and break said ice masses.
Claim 8
Dependent Claim
75 words
The offshore structure of claim 1 wherein said upper portion of said caisson has an opposed double cone shape comprising a truncated cone in vertical abutting relationship with an inverted truncated cone, the junction of said cones being maintained at approximately the sea surface and wherein said means for vertically moving said caisson permits said upper portion to move in both a downward direction and an upward direction to strike and break said ice masses.
Claim 9
Dependent Claim
21 words
The offshore structure in claim 1 wherein said caisson has a conically shaped upper portion and a cylindrically shaped lower portion.
Claim 10
Dependent Claim
21 words
The offshore structure in claim 1 wherein said caisson has an overall vertical length of between about 200 and 800 feet.
Claim 11
Dependent Claim
27 words
The offshore structure in claim 1 wherein the distance between the center of gravity and the center of buoyancy of said caisson is at least 20 feet.
Claim 12
Dependent Claim
21 words
The offshore structure in claim 1 wherein said caisson has a dead weight of between about 250 and 600 million pounds.
Claim 13
Dependent Claim
24 words
The offshore structure of claim 1 wherein said mooring lines are secured to the bottom of said body of water by clump weight anchors.
Claim 14
Dependent Claim
21 words
The offshore structure of claim 1 wherein said mooring lines have a maximum allowable tension of at least 1 million pounds.
Claim 15
Dependent Claim
27 words
The offshore structure of claim 1 wherein said means for vertically moving said caisson comprises a pulling machine which actuates cable grips attached to said mooring lines.
Claim 16
Dependent Claim
110 words
An offshore structure which is adapted for drilling operations in an ice infested arctic sea comprising: a floating caisson, said caisson having an upper portion which is radially downwardly tapered at an angle of between about 30° and 60° from the vertical; a plurality of mooring lines secured at a first end to said caisson and at a second end to the sea floor; and means for tensioning and untensioning said mooring lines so that said caisson can be moved vertically a sufficient distance and with sufficient dynamic force to permit said upper portion of said caisson to obliquely contact and break floating ice masses which impinge upon said caisson.
Claim 17
Dependent Claim
110 words
An offshore structure which is adapted for drilling operations in an ice infested arctic sea comprising: a floating caisson, said caisson having an upper portion which is radially downwardly tapered at an angle of between about 30° and 60° from the vertical; a plurality of mooring lines secured at a first end to said caisson and at a second end to the sea floor; and means for tensioning and untensioning said mooring lines so that said caisson can be moved vertically a sufficient distance and with sufficient dynamic force to permit said upper portion of said caisson to obliquely contact and break floating ice masses which impinge upon said caisson.
Claim 18
Dependent Claim
58 words
In a method conducting drilling operations from a floating caisson in an arctic sea containing floating ice masses, said caisson having a radially downwardly tapered upper ice-breaking portion, the improvement comprising vertically moving said caisson a sufficient distance and with sufficient dynamic force so that the upper portion of said caisson obliquely contacts and breaks said ice masses.
Claim 19
Dependent Claim
58 words
In a method conducting drilling operations from a floating caisson in an arctic sea containing floating ice masses, said caisson having a radially downwardly tapered upper ice-breaking portion, the improvement comprising vertically moving said caisson a sufficient distance and with sufficient dynamic force so that the upper portion of said caisson obliquely contacts and breaks said ice masses.
Claim 20
Dependent Claim
16 words
The method claim 16 wherein said caisson is vertically moved a distance of about 7 feet.
Claim 21
Dependent Claim
84 words
In a method of conducting drilling operations from a floating caisson in an arctic sea containing floating ice masses, said caisson having a radially downwardly tapered upper ice-breaking portion and being secured to the sea floor by a plurality of mooring lines attached to said caisson, the improvement comprising: sequentially tensioning and untensioning said mooring lines to vertically move said caisson a sufficient distance and with sufficient dynamic force so that the upper portion of said caisson obliquely contacts and breaks said ice masses.
Claim 22
Dependent Claim
84 words
In a method of conducting drilling operations from a floating caisson in an arctic sea containing floating ice masses, said caisson having a radially downwardly tapered upper ice-breaking portion and being secured to the sea floor by a plurality of mooring lines attached to said caisson, the improvement comprising: sequentially tensioning and untensioning said mooring lines to vertically move said caisson a sufficient distance and with sufficient dynamic force so that the upper portion of said caisson obliquely contacts and breaks said ice masses.
Claim 23
Dependent Claim
17 words
The method of claim 18 wherein said caisson is vertically moved a distance of about 7 feet.
References Cited (Backward Citations)
US3766874A
Cited
US3807179A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |