Sliding-resistant bottom-founded offshore structures

• US 6,203,248 B1
• Filed: 02/03/2000
• Issued: 03/20/2001
• Est. Priority Date: 02/03/2000
• Status: Expired due to Term

• Current Assignee: Atwood Oceanics Incorporated (Valaris Ltd.)
• Original Assignee: Atwood Oceanics Incorporated (Valaris Ltd.)
• Inventors: Rowan, David, Childers, Mark A., Quintero, Alan
• Primary Examiner(s): Neuder, William
• Assistant Examiner(s): Pechhold, Alexandra K.
• Application Number:
  US09/497,445
• Time in Patent Office: 411 Days
• Field of Search: 405/195.1, 405/224, 405/224.1, 405/227, 405/228, 114/296
• US Class Current: 405/227
• CPC Class Codes: E02B 17/02 placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
• CPC Class Codes: E02B 2017/0078 Suction piles, suction cans
• CPC Class Codes: E02B 2017/0086 Large footings connecting several legs or serving as a reservoir for the storage of oil or gas
• CPC Class Codes: E02D 11/00 Methods or apparatus specially adapted for both placing and removing sheet pile bulkheads, piles, or mould-pipes features relating to placing only E02D7/00, to removing only E02D9/00 ; placing apparatus which without special provisions, can be operated to remove, e.g. vibrating drivers E02D7/00
• CPC Class Codes: E02D 2250/0053 using suction or vacuum techniques
• CPC Class Codes: E02D 27/52 Submerged foundations , i.e. submerged in open water E02D27/12 - E02D27/24 take precedence
• CPC Class Codes: E02D 7/20 Placing by pressure or pulling power

Abstract

A bottom-founded offshore structure in relatively shallow waters is protected against sliding. It uses at least one pile and a suction pump inside the pile. The pile has a length-to-diameter ratio such as to achieve sufficient pile imbedment with the selected suction pump. A dedicated pile lowering and lifting device lowers and lifts the pile as needed. Guides allow the pile'"'"'s vertical motion and limit its rotational motion during imbedment and extraction. A stop device limits the vertical motion of the pile'"'"'s top rim during pile extraction. The pile is reusable, light weight, easy to install and to extract, self-contained, and economical in relationship to its high holding power when imbedded.

Claims

1. A slide-resistant, bottom-founded structure for use over the waterbed of a relatively shallow waterway, comprising:

at least one pile having a generally circular section and a top end movably mounted on said structure;

a self-contained imbedment system operatively associated with said at least one pile and with said structure for imbedding said at least one pile into the earth foundation underneath said waterbed;

said embedment system including a predetermined suction pump inside said at least one pile;

said at least one pile having a length-to-diameter ratio sufficient to achieve said imbedment of said at least one pile using said predetermined suction pump; and

said pump, in use, pumping out water from said at least one pile and creating therewithin a sufficient under-pressure to forcibly imbed said at least one pile into said earth foundation.

2. The slide-resistant, bottom-founded structure according to claim 1, wherein

said structure has a hull;

said at least one pile is mounted on said hull of said structure;

said length-to-diameter ratio of said at least one pile is within the range of 0.5;

1 to 5;

1; and

control instrumentation means mounted on said structure and within said at least one pile for controlling the operation of said suction pump, and of said under-pressure within said at least one pile.

3. The slide-resistant, bottom-founded structure according to claim 2, and

means supplying a pressurized fluid into said at least one pile when imbedded to create a sufficient over-pressure therewithin to forcibly extract said at least one pile from said earth foundation;

and

diaphragm means inside said at least one pile for containing said under-pressure during said imbedment and said over-pressure during said extraction.

4. The slide-resistant, bottom-founded structure according to claim 3, and

coupling means for releasably coupling said top end of said at least one pile to said structure.

5. The slide-resistant, bottom-founded structure according to claim 4, wherein

said coupling means includes a padeye.

6. The slide-resistant, bottom-founded structure according to claim 4, and

a pile lowering-and-lifting device operatively mounted on said structure above said at least one pile for lowering said at least one pile to said waterbed during said at least one imbedment of said at least one plie, and for lifting said pile out of said waterbed during said extraction of said at least one pile.

7. The slide-resistant, bottom-founded structure according to claim 6, wherein

said lowering-and-lifting device is a winch and tackle apparatus mounted over the center axis of said at least one pile.

8. The slide-resistant, bottom-founded structure according to claim 4, wherein

said structure is a submersible structure having a main deck supported on a bottom-founded substructure which, in use, rests on said waterbed at a location subject to severe environmental conditions;

and

said at least one pile has a substantially circular section;

said length-to-diameter ratio of said pile is selected so as to empower said structure to resist sliding over said waterbed.

9. The slide-resistant, bottom-founded structure according to claim 7, and

stop-and-guide means on said structure and on said at least one pile for limiting the vertical motion of said top end of said at least one pile during said extraction of said at least one pile, and its rotational motion during said embedment of said at least one pile.

10. The slide-resistant, bottom-founded structure according to claim 9, wherein

said at least one pile has drain holes to allow excess water to escape from said at least one pile during said extraction of said at least one pile and to allow free-flooding said at least one pile during said embedment of said at least one pile;

and

jetting means for directing high-pressure water to the lower end of said at least one pile to assist with said pile'"'"'s imbedment.

11. A slide-resistant, bottom-founded structure which, in normal use, is stationed at a rest position on the bed of a relatively shallow waterway, comprising:

at least one pile having a top end and a bottom base;

coupling means for releasably and movably coupling said top end to said structure;

an imbedment system operatively coupled to said pile;

said imbedment system including a suction pump mounted inside said at least one pile for forcibly imbedding said base into said bed, thereby increasing the slide resistance of said bottom-founded structure; and

control instrumentation means mounted on said structure and on said at least one pile for monitoring and controlling the performance of said suction pump.

12. The slide-resistant, bottom-founded structure according to claim 11, wherein

said at least one pile has a generally circular section and a length-to-diameter ratio within a range of 0.5: 1 to 5;

1.

13. The slide-resistant, bottom-founded structure according to claim 11, and

a lowering-and-lifting device operatively coupled to said structure and to said at least one pile for lowering said at least one pile to said bed.

14. The slide-resistant, bottom-founded structure according to claim 13, wherein

said lowering-and-lifting device includes a winch-and-tackle apparatus.

15. The slide-resistant, bottom-founded structure according to claim 13, and

a fluid supply source for feeding a high-pressure fluid into said at least one pile, when imbedded, thereby extracting said base of said at least one pile from said bed.

16. The slide-resistant, bottom-founded structure according to claim 15, and

diaphragm means within said at least one pile for containing the fluid pressure therein during said imbedment of at least one pile and said extraction of said at least one pile.

17. The slide-resistant, bottom-founded structure according to claim 15, wherein

said at least one pile has drain holes to allow water to escape therefrom during said extraction of said at least one pile, and to allow free-flooding said at least one pile during said imbedment of said at least one pile.

18. The slide-resistant, bottom-founded structure according to claim 15, and

jetting means coupled to said fluid source and to said at least one pile for assisting, when necessary, with said imbedment of said at least one pile and said extraction of said at least one pile.

19. The slide-resistant, bottom-founded structure according to claim 12, wherein

said length-to-diameter ratio is selected range to enable said structure to optimally resist sliding over said bed under the worst expected environmental conditions.

20. The slide-resistant, bottom-founded structure according to claim 11, wherein

said structure has a hull resting, in use, over said bed;

and

said at least one pile has a generally circular section and a length-to-diameter ratio within a range of 0.5;

1 to 5;

1.

21. A slide-resistant, bottom-founded offshore structure which, in normal use, is stationed at a rest position on the seabed of a relatively shallow seaway, comprising:

a plurality of piles, each one of said piles having a top end and a bottom base;

coupling means for releasably and movably coupling said top end of each one of said piles to said structure;

an imbedment system operatively coupled to each one of said piles;

said imbedment system including a suction pump mounted inside each one of said piles for forcibly imbedding each of said pile'"'"'s base into said seabed, thereby increasing the slide resistance of said bottom-founded structure; and

control instrumentation means mounted on said structure and on each one of said piles for monitoring and controlling the performance of each suction pump within each one of said piles.

22. The slide-resistant, bottom-founded offshore structure according to claim 21, wherein

each one of said piles has a generally circular section and a length-to-diameter ratio within a range of 0.5: 1 to 5;

1.

23. The slide-resistant, bottom-founded offshore structure according to claim 22, wherein

said length-to-diameter ratio is selected range to enable said structure to optimally resist sliding over said seabed under the worst expected environmental conditions.

24. The offshore structure according to claim 21, wherein

said structure has a hull resting, in use, over said seabed;

each one of said piles has a generally circular section and a length-to-diameter ratio within a range of 0.5;

1 to 5;

1; and

stop-and-guide means on said structure and on each one of said piles for limiting the vertical motion of each of said pile'"'"'s top end during said pile extraction, and its rotational motion during said pile imbedment.

25. The slide-resistant, bottom-founded offshore structure according to claim 21, and

a lowering-and-lifting device operatively coupled to said structure and to each one of said piles for lowering each of said pile'"'"'s base to said seabed.

26. The slide-resistant, bottom-founded offshore structure according to claim 25, wherein

said lowering-and-lifting device includes a winch-and-tackle apparatus.

27. The slide-resistant, bottom-founded offshore structure according to claim 25, and

a fluid supply source for feeding a high-pressure fluid into each one of said piles, when imbedded, thereby extracting each one of said piles from said seabed.

28. The slide-resistant, bottom-founded offshore structure according to claim 27, and

jetting means coupled to said fluid source and to each one of said piles for assisting, when necessary, with said pile imbedment and said pile extraction.

29. The slide-resistant, bottom-founded offshore structure according to claim 27, wherein

each one of said piles has drain holes to allow seawater to escape therefrom during said pile extraction, and to allow free-flooding during said pile embedment.

30. The slide-resistant, bottom-founded offshore structure according to claim 27, and

diaphragm means within each one of said piles for containing the fluid pressure therein during said pile imbedment and said pile extraction.