US3602319A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Structure with varying cross-sectional moment of inertia
Assignee: Global Marine Inc
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Filing: 1969-09-26
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Granted: 1971-08-31
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Expires: 1989-09-26
Abstract
Abstract A structure is described for mounting on a drilling vessel for drilling of submarine wells and the like. A guide horn beneath the conventional drill rig on the ship is in the form of a portion of the surface of a torus. The drill string passes through the guide horn so that any angular misalignment between the drill string at the sea floor and the drill string at the ship due to the ship''s roll or the like, is distributed along the surface of the guide horn as a gradual curve over a sufficient length of the drill string that the maximum fiber stress in the drill string is less than the fatigue limit of the drill string. The guide horn has a small entrance aperture at its upper end adjacent the drill rig and flares in a circular arc to an enlarged exit aperture adjacent the bottom of the ship. For drilling in deep water, a portion of the guide horn is replaced with an elongated tubular member that surrounds the drill string and is fixed to the ship at its upper end as a downwardly extending cantilevered structure. The elongated tubular member has a gradually diminishing cross-sectional moment of inertia so that the drill string within the tubular member is constrained to bend in a substantially circular arc of large radius. In its more rigid portion, the elongated member has a gradually tapering wall thickness. In its more flexible portion, the elongated tubular member comprises a plurality of axially aligned rings in end-to-end relation, surrounded by and substantially flexibly interconnected by a cage. The cage has longitudinally extending ribs with each rib having a gradually tapering cross section.
Inventors
- 👤 John R Graham
- 👤 Thad Vreeland Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:39
CPC Classifications
E; E21; E21B; E21B15/00; E21B15/02; E21B17/00; E21B17/01; E21B17/017
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
74 words
An elongated structure having a gradually changing crosssectional moment of inertia along its length comprising: a plurality of substantially rigid ringlike sleeves in end-toend relation along the length of the structure; and a cage surrounding the rings having a plurality of parallel ribs extending along the length of the structure, each of the ribs being connected at one point to each of the sleeves, each of the ribs having a gradually changing cross-sectional area.
Claim 2
Dependent Claim
74 words
An elongated structure having a gradually changing crosssectional moment of inertia along its length comprising: a plurality of substantially rigid ringlike sleeves in end-toend relation along the length of the structure; and a cage surrounding the rings having a plurality of parallel ribs extending along the length of the structure, each of the ribs being connected at one point to each of the sleeves, each of the ribs having a gradually changing cross-sectional area.
Claim 3
Dependent Claim
27 words
An elongated structure as defined in claim 1, wherein each of the sleeves has a shorter length than the previous sleeve along the length of the structure.
Claim 4
Dependent Claim
37 words
A structure as defined in claim 1, further comprising: means between each pair of sleeves for enabling a limited longitudinal translation and for preventing substantial relative rotation of adjacent sleeves about the longitudinal axis of the structure.
Claim 5
Dependent Claim
49 words
A structure as defined in claim 1, wherein the ribs are interconnected circumferentially at each end of the elongated structure, and each rib has an arcuate cross section having a concave side adjacent the exterior of the sleeves, the arc length gradually decreasing along the length of the structure.
Claim 6
Dependent Claim
77 words
A structure as defined in Claim 4, wherein each of the sleeves has a shorter length than the previous sleeve along the length of the structure, the relativEly longer sleeve being nearer the greater cross-sectional area of the ribs and the relatively shorter sleeve being nearer the smaller cross-sectional area of the rib and further comprising: means between each pair of sleeves for enabling a limited longitudinal translation and for preventing substantial relative rotation of adjacent sleeves.
Claim 7
Dependent Claim
142 words
Apparatus for improved control of bending of a drill string extending between a drilling rig fixed on a floating drilling ship and the sea floor, said apparatus comprising: an elongated tubular member connected at its upper end to the ship in alignment with the drilling rig for passing the drill string therethrough and extending to a free lower end, said elongated tubular member having a gradually varying cross-sectional moment of inertia along its length with a relatively larger cross-sectional moment of inertia at the end connected to the ship and a relatively smaller cross-sectional moment of inertia at the free end, said tubular member comprising: at least a portion having a plurality of parallel tapered ribs extending longitudinally along the tubular member to form a cage; and a plurality of ringlike segments within the cage substantially freely articulatible relative to each other.
Claim 8
Dependent Claim
142 words
Apparatus for improved control of bending of a drill string extending between a drilling rig fixed on a floating drilling ship and the sea floor, said apparatus comprising: an elongated tubular member connected at its upper end to the ship in alignment with the drilling rig for passing the drill string therethrough and extending to a free lower end, said elongated tubular member having a gradually varying cross-sectional moment of inertia along its length with a relatively larger cross-sectional moment of inertia at the end connected to the ship and a relatively smaller cross-sectional moment of inertia at the free end, said tubular member comprising: at least a portion having a plurality of parallel tapered ribs extending longitudinally along the tubular member to form a cage; and a plurality of ringlike segments within the cage substantially freely articulatible relative to each other.
Claim 9
Dependent Claim
24 words
Apparatus as defined in Claim 6, wherein the ringlike segments are connected intermittently to the ribs in end-to-end relation to form a tubular member.
Claim 10
Dependent Claim
32 words
Apparatus as defined in Claim 7, further comprising means for interconnecting ends of adjacent ringlike segments for preventing substantial relative rotation of adjacent sleeves about the longitudinal axis of the tubular member.
Claim 11
Dependent Claim
157 words
A drilling guide for a floating drilling vessel comprising: an elongated tubular member having a cylindrical bore sufficiently large to accommodate a drill string; means on the tubular member for aligning an end of the member with the drilling vessel; means on the tubular member for varying the cross-sectional moment of inertia of the tubular member as a function of its length with a relatively larger cross-sectional moment of inertia adjacent to the end aligned with the drilling vessel and a relatively smaller cross-sectional moment of inertia adjacent to the opposite end, said means for varying comprising at least in part: a plurality of tapered ribs extending longitudinally along the tubular member to form a cage; and wherein the tubular member comprises a plurality of ringlike segments in end-to-end alignment within the cage and intermittently connected to the tapered ribs and otherwise substantially free to mutually articulate in a direction to accommodate bending of the tubular member.
Claim 12
Dependent Claim
157 words
A drilling guide for a floating drilling vessel comprising: an elongated tubular member having a cylindrical bore sufficiently large to accommodate a drill string; means on the tubular member for aligning an end of the member with the drilling vessel; means on the tubular member for varying the cross-sectional moment of inertia of the tubular member as a function of its length with a relatively larger cross-sectional moment of inertia adjacent to the end aligned with the drilling vessel and a relatively smaller cross-sectional moment of inertia adjacent to the opposite end, said means for varying comprising at least in part: a plurality of tapered ribs extending longitudinally along the tubular member to form a cage; and wherein the tubular member comprises a plurality of ringlike segments in end-to-end alignment within the cage and intermittently connected to the tapered ribs and otherwise substantially free to mutually articulate in a direction to accommodate bending of the tubular member.
Claim 13
Dependent Claim
52 words
A drilling guide as defined in Claim 9, wherein the length of adjacent ringlike segments differs with a segment having a relatively shorter length relatively closer to the smaller end of the tapered ribs and a segment having a relatively longer length relatively closer to the larger end of the tapered ribs.
Claim 14
Dependent Claim
28 words
A drilling guide as defined in Claim 10, further comprising: means interconnecting adjacent ringlike segments for conveying shear and torsion loads therebetween and for permitting limited longitudinal articulation.
Claim 15
Dependent Claim
106 words
A drilling guide as defined in Claim 10, wherein the means for varying the cross-sectional moment of inertia further comprises: a tubular section having a higher cross-sectional moment of inertia than the section including the ribs and segments and having a gradually decreasing outside diameter with increasing distance from the means for aligning, the end of the tubular section having the relatively lower cross-sectional moment of inertia connected in end-to-end relation with the end of the rib section having the relatively higher cross-sectional moment of inertia so that the variation in cross-sectional moment of inertia with increasing distance from the means for aligning is substantially continuous.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |