Jack-up drilling platform

Claim 2

In a mobile drilling platform, a hull, a plurality of legs movably secured to said hull, each of said legs having a plurality of separable longitudinal sections, means for shifting said legs longitudinally thereof relative to said hull for causing said legs to project varying distances above and below said hull, an upstanding structure, means for selectively propelling said upstanding structure into the vicinity of said legs, a carriage movable along said upstanding structure, and grapple means on said carriage for securement to the upper sections of said legs for lifting and lowering the attached leg sections.

Claim 3

A mobile drilling platform as described in claim 1 in which said upstanding structure is a drilling derrick.

Claim 4

A mobile drilling structure as described in claim 1 in which said upstanding structure is mounted for rotation about its vertical axis to position said grapple means for securement to a leg section.

Claim 5

A mobile drilling platform as described iN claim 1 in which said grapple means includes a plurality of leg-securing devices spaced substantially apart vertically for preventing swinging of a detached and supported leg section.

Claim 6

A mobile drilling platform as described in claim 1 in which said legs are of truss construction each with a plurality of structural chords, said grapple means including horizontally spaced leg-securing devices positioned to grip a plurality of said chords.

Claim 7

A mobile drilling platform as described in claim 1 in which said legs are of truss construction each with a pair of structural chords substantially in a plane, said grapple means including a plurality of leg securing devices positioned to grip each of said chords at areas substantially spaced apart longitudinally.

Claim 8

A mobile drilling platform as described in claim 1 further including complementary shoulder means on said upstanding structure and said upper leg sections positioned to interengage when said upstanding structure and a leg section are secured together, said grapple means further including a securing element for encompassing at least a part of said upper leg section and to maintain said shoulder means in engagement for resisting dropping of said leg section.

Claim 9

A mobile drilling platform as described in claim 7 in which said complementary shoulder means comprise interfittable rack elements.

Claim 10

A mobile drilling platform as described in claim 8 in which the rack elements on said upper leg section constitute parts of said means for shifting the said leg axially with respect to said hull.

Claim 11

A mobile drilling platform as described in claim 7 in which said securing element comprises a pivoted lever.

Claim 12

A mobile drilling platform as described in claim 1 further including detachably interlocking joint elements on abutting upper and underlying leg sections.

Claim 13

A mobile drilling platform as described in claim 11 in which joint elements corresponding to the joint elements at the top of the underlying leg sections are secured to said hull for anchoring detached upper leg sections in upstanding positions.

Claim 14

A mobile drilling platform as described in claim 5 in which said legs are of triangular section each with three corner chords connected by bracing.

Claim 15

A mobile drilling platform having a floatable hull and a plurality of legs movably mounted on said hull, powered means for shifting said legs longitudinally relative to said hull to cause said legs to variably protrude above and beneath said hull and to lift said hull when said legs are on bottom, a drilling derrick movably mounted on said hull, said legs each having multiple longitudinal sections detachably secured together, grapple means movably mounted on one side of said derrick including elements for encompassing at least a part of an upper leg section, second powered means for moving said derrick to and from its drilling position and positions adjacent said legs, and third powered means for propelling said grapple means up and down on said derrick, first for bringing said grapple means abreast an upper section of a leg, then lifting said upper section to separate it from its underlying section after said grapple means is secured to said upper section, and then, after said derrick is moved away from said underlying section, lowering said upper section onto said hull for lowering the center of gravity of the platform.

Claim 16

A mobile drilling platform having a floatable hull and a plurality of legs movably mounted on said hull, powered means for shifting said legs longitudinally relative to said hull to cause said legs to variably protrude above and beneath said hull and to lift said hull when said legs are on bottom, a drilling derrick movably mounted on said hull, said legs each having multiple longitudinal sections detachably secured together, grapple means movably mounted on one side of said derrick including elements for encompassing at least a part of an upper leg section, second powered means for moving said derrick to and from its drilling position and positions adjacent said legs, and third powered means for propelling said grapple means up and down on said derrick, first for bringing said grapple means abreast an upper section of a leg, then lifting said upper section to separate it from its underlying section after said grapple means is secured to said upper section, and then, after said derrick is moved away from said underlying section, lowering said upper section onto said hull for lowering the center of gravity of the platform.

Claim 17

A mobile drilling platform as described in claim 14 in which said legs extend through wells in said hull, and further including powered drive pinions and racks mounted respectively on each well wall and the corresponding leg, and said grapple means including a rack section for meshing with the rack on the leg section to which it is secured to resist dropping of said secured leg section.

Claim 18

A mobile drilling platform as described in claim 14 in which said derrick is of truss construction, including at least a pair of structural chords on one side, said grapple means comprising a carriage riding along said latter chords and guidE means engaging longitudinally spaced parts of said latter chords to resist separation of said carriage from said derrick.

Claim 19

A mobile drilling platform as described in claim 14 further including a base for said derrick slidable along said hull, said derrick being movably mounted on said base for improved juxtaposition between said derrick and the platform leg being manipulated.

Claim 20

A mobile drilling platform as described in claim 14 further including tracks on said hull extending from a central position on said hull to a drilling recess spaced therefrom and also to positions adjacent said legs, and bearing elements on the bottom portions of said derrick for riding on said tracks.