SEABED BACKFILL PLOW AND METHOD

• US 20160356015A1
• Filed: 08/22/2016
• Published: 12/08/2016
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Oceaneering International Services Limited (Oceaneering International Incorporated)
• Original Assignee: Oceaneering International Services Limited (Oceaneering International Incorporated)
• Inventors: Wilson, Michael W. N.
• Granted Patent: US 10,519,624 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E02F 5/006 adapted for working ground under water not otherwise provided for E02F3/081, E02F3/4131, E02F3/8833, E02F5/104, E02F5/125, E02F7/005, E02F7/023, E02F7/065, E02F9/026, E02F9/045, E02F9/06 take precedence
• CPC Class Codes: E02F 5/027 with coulters, ploughs, scraper plates, or the like E02F5/102, E02F5/103, E02F5/106 take precedence
• CPC Class Codes: E02F 5/106 using ploughs, coulters, rippers
• CPC Class Codes: E02F 5/125 underwater
• CPC Class Codes: E02F 5/14 Component parts for trench excavators, e.g. indicating devices travelling gear chassis, supports, skids
• CPC Class Codes: H02G 1/10 in or under water

Abstract

A BAS plow creates a V-trench along the linear route of a pipeline path and an instrumented bottle moving with the BAS plow collects BAS data indicative of the pitch, roll, heading, yaw, three dimensional positioning, speed and depth of the chassis, the shearing force applied to the seabed material and the applied tow force. The bottle can be swapped to collect the acquired data or an umbilical can be used to provide a real time stream of data. The BAS plow can simultaneously backfill the created trench, leaving an undisrupted seabed, or the pipeline can be laid in the BAS trench, which can also be made deeper and wider by additional trench cutting passes, significantly reducing the total time required for combined BAS and pipeline laying processes. The BAS plow can be released and retrieved over-the-stern of a towing vessel.

Claims

1. For backfilling spoil into a seabed trench, a plow comprising:

a chassis;

a skid supporting an aft end of said chassis above the seabed;

moldboards mounted on said chassis forward of said skid, said moldboards being sized and oriented to span the trench and funnel spoil disposed on the seabed laterally of the trench toward the center of the trench as the plow travels forward on the seabed; and

a blade mounted on and spanning bottom edges of said moldboards to collect the spoil in its path as the plow travels forward on the seabed, said blade having a passage at a rear apex thereof configured to dispense spoil collected by said blade and funneled by said moldboards to said passage on top of a pipe disposed in the trench below said passage.

2. A plow according to claim 1 further comprising a flapper board aft of said passage fragmenting spoil discharged through said passage.

3. A plow according to claim 2, said flapper board comprising:

a plate swinging below a horizontal shafts; and

a weight biasing said plate toward a vertical orientation.

4. A plow according to claim 1, said skid being configured to straddle the trench.

5. A plow according to claim 4, said skid comprising:

a crossbar mounted on a rear end of said chassis;

a pair of skid posts, one on each end of said crossbar; and

a pair of skis, one on a bottom of each said post.

6. A plow according to claim 5, said crossbar having a front surface adapted to level spoil discharged into the trench.

7. A plow according to claim 1, at least one of said chassis, said moldboards, said blade and said skid having a surface contoured to pivot about a fulcrum on a stern of a vessel contacting said surface as the plow crosses the fulcrum during release of the plow to the sea from the vessel and during retrieval of the plow from the sea to the vessel.

8. A plow according to claim 7, longitudinal vertical cross-sections of said surface being concave.

9. A plow according to claim 8, said chassis, said moldboards, said blade and said skid being in weight and contact surfaces with the fulcrum coordinated to resist roll of the plow about its transition axis.

10. A plow according to claim 9, the fulcrum being a roller and the plow further comprising towing points for connection of a towing line to the plow, said points being symmetrically arranged in relation to a longitudinal axis of said chassis and being displaced from a bottom of the plow by a height less than a radius of the roller.

11. A plow according to claim 9 further comprising keel plates, said blade having at least two said keel plates spaced apart and extending thereunder.

12. A plow according to claim 11, the fulcrum being a roller and the plow further comprising towing points for connection of a towing line to the plow, said points being symmetrically arranged in relation to a longitudinal axis of said chassis and being displaced from a bottom of the plow by a height less than a radius of the roller.

13. A method of backfilling spoil into a seabed trench comprising the steps of:

propelling a blade to travel forward on the seabed and collect spoil along the sides of the trench;

funneling the collected spoil toward a rear apex of the blade; and

allowing the funneled spoil to be discharged through an opening in the blade apex and onto a top surface of a pipe disposed in the trench.

14. A method according to claim 13 further comprising the step of leveling the spoil discharged into the trench.

15. A method according to claim 13 further comprising the step of fragmenting the discharged spoil before the discharged spoil reaches the pipe.

16. A method according to claim 15 further comprising the step of leveling the spoil discharged into the trench.

17. A method of backfilling spoil into a seabed trench comprising the steps of:

propelling a backfill plow on the deck of a vessel toward and across a fulcrum on a stern of the vessel;

allowing the plow to rotate about the fulcrum as the plow crosses the fulcrum and is released from the fulcrum into the sea; and

lowering the released plow at towing line end to the seabed.

18. A method according to claim 17 followed by the step of towing the plow to backfill the trench.

19. A method according to claim 18 followed by the steps of:

raising the plow at towing line end toward the fulcrum on the stern of the vessel; and

pulling the plow across the fulcrum onto the deck of the vessel.