Mobile, offshore, jack-up, marine platform adjustable for sloping sea floor

• US 4,583,881 A
• Filed: 05/29/1984
• Issued: 04/22/1986
• Est. Priority Date: 05/29/1984
• Status: Expired due to Fees

• Current Assignee: James E. Steele
• Original Assignee: Bethlehem Steel Corporation (ArcelorMittal SA)
• Inventors: Steele, James E.
• Primary Examiner(s): Taylor, Dennis L.
• Application Number:
  US06/614,585
• Time in Patent Office: 693 Days
• Field of Search: 405/196-198, 405/203, 405/204, 405/205, 405/207, 405/208, 405/224, 405/227
• US Class Current: 405/198
• CPC Class Codes: E02B 17/021 with relative movement between supporting construction and platform
• CPC Class Codes: E02B 17/027 steel structures E02B17/021 takes precedence
• CPC Class Codes: E02B 17/0809 the equipment being hydraulically actuated outriggers for cranes B66C23/80
• CPC Class Codes: E02B 17/0872 with locking pins engaging holes or cam surfaces
• CPC Class Codes: E02B 2017/006 with lattice style supporting legs
• CPC Class Codes: E02B 2017/0086 Large footings connecting several legs or serving as a reservoir for the storage of oil or gas

Abstract

A mobile, offshore, jack-up, marine platform, adjustable for sloping sea floor having a mat, a multilegged column pivotally connected thereto and a work platform slidably mounted on the column. Means are included for independently vertically adjusting at least one leg and for selectively cantilevering a drilling unit on the work platform, with offset ballasting of the work platform.

Claims

1. A mobile, offshore, jack-up, marine platform adjustable for sloping sea floor comprising:

(a) a mat;

(b) a tiltable column having a plurality of hollow tubular legs, each leg pivotally attached to the mat;

(i) means on at least one leg for independently vertically raising and lowering such leg with respect to the mat, to tilt the column;

(c) a jack-up work platform slidably mounted through its central portion on the column, the work platform having a pair of parallel fixed cantilevered arms extending outwardly from the central portion and a ballastable portion opposite the cantilevered arms;

(d) a skid unit movably mounted on the cantilevered arms of the work platform; and

(e) a jack-up means interconnected between the work platform and each leg of the column for vertically moving the work platform with respect to the mat.

2. The invention of claim 1 further comprising:

(a) each jack-up means (e) including;

(i) a first and second vertically spaced semi-circular yoke spanning an outboard portion of each leg;

(ii) a plurality of vertically-oriented piston and cylinder assemblies interconnecting said first and second yokes; and

(iii) each yoke carrying a plurality of vertically-spaced, horizontally-oriented piston and cylinder assemblies which serve to selectively engage vertically-spaced apertures in the leg with reciprocating anchor pins.

3. The invention of claim 2 in which the legs of the column are cross-braced by:

(a) in a first horizontal plane adjacent the mat;

(i) a horizontally disposed outer strut connecting each pair of legs;

(ii) a pair of diagonal struts fastened to the midpoint of each outer strut, each diagonal strut extending downwardly to fixedly connect to a different leg of the pair of legs; and

(iii) the outer strut and diagonal struts being pivotally connected at the outer strut midpoint;

(b) in a plurality of horizontal planes above the first horizontal plane;

(i) outer struts similarly disposed to (a) (i);

(ii) diagonal struts similarly disposed to (a) (ii); and

(iii) the outer struts and diagonal struts being fixedly fastened to each other and to the legs of the column; and

(c) an inner strut connecting each pair of outer struts at the midpoint thereof, in a given plane.

4. The invention of claim 1 in which the means (b)(i) on each leg includes:

(a) a pivotal shaft rotatably threadably connected to the inside of the hollow leg, the shaft having means for pivoting in all directions as it rotates; and

(b) means for rotating the shaft to raise and lower the leg in relation to the mat.

5. The invention of claim 4 further including a plurality of hollow anchoring spuds extendable through the mat into the sea floor.

6. The invention of claim 5 wherein the column includes a plurality of riser supports at a plurality of vertical elevations pivotally connected to the column.

7. The invention of claim 1 in which the skid unit can be cantilevered out beyond the end of the fixed cantilevered arms.

8. The invention of claim 7 in which the skid unit is horizontally universally movable and carries a pipe storage rack.

9. The invention of claim 1 in which a pair of legs of the column are adjacent the fixed cantilevered arms, with a third leg oppositely spaced from the pair of legs, whereby the column, in horizontal cross-section, forms a triangle.

10. The invention of claim 9 in which the central portion of the work platform includes a plurality of compartments surrounding the column, wherein some of the compartments are ballastable.

11. The invention of claim 4 in which the means 4 (b) for rotating the shaft includes within the leg:

(a) a spline portion fixed to the shaft;

(b) a first pair of horizontally-oriented hydraulic cylinders in opposing relation pivotally fastened to the leg, for rotating the shaft;

(c) a pair of yokes pivotally fastened to the first pair of cylinders;

(d) a second pair of horizontally-oriented hydraulic cylinders in the yokes, for diametrically inserting and withdrawing a pair of jacking pins into the spline.

12. The invention of claim 4 in which the means 4 (b) for rotating the shaft includes:

(a) a first bevel gear affixed to the shaft;

(b) a second bevel gear engaged therewith and rotatably driven by a chain and sprocket combination extending from the work platform.

13. The invention of claim 4 in which means 4(b) for rotating the shaft includes within each leg:

(a) a leg portion having a plurality of helical grooves spiralling downwardly along the inner surface of the leg;

(b) a plurality of parallel vertical flutes on the upper end of the shaft;

(c) a vertically reciprocal twist sleeve having a first means for engaging the flutes, and a second means for selectively engaging and disengaging the helical grooves; and

(d) means for vertically reciprocating the twist sleeve.

14. The invention of claim 4 further including:

(a) a lower leg portion fixed to the mat, the lower leg portion carrying;

(i) a lower spherical bearing seat; and

(ii) an upper tubular section extending above the mat ending in an upper spherical bearing seat;

(b) the shaft terminating in a lower spherical bearing pad against lower spherical bearing seat and an upper spherical bearing pad against upper spherical bearing seat; and

(c) means for sealing between the lower portion of the leg and the upper tubular section.