GB2230072A - Transporting seabed material - Google Patents

Transporting seabed material Download PDF

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Publication number
GB2230072A
GB2230072A GB9007404A GB9007404A GB2230072A GB 2230072 A GB2230072 A GB 2230072A GB 9007404 A GB9007404 A GB 9007404A GB 9007404 A GB9007404 A GB 9007404A GB 2230072 A GB2230072 A GB 2230072A
Authority
GB
United Kingdom
Prior art keywords
pipeline
free span
fill material
pump means
pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9007404A
Other versions
GB9007404D0 (en
Inventor
Peter Robin Langley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
OFFSHORE PROJECT MANAGEMENT SU
Original Assignee
OFFSHORE PROJECT MANAGEMENT SU
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB898907411A external-priority patent/GB8907411D0/en
Priority claimed from GB898907543A external-priority patent/GB8907543D0/en
Application filed by OFFSHORE PROJECT MANAGEMENT SU filed Critical OFFSHORE PROJECT MANAGEMENT SU
Publication of GB9007404D0 publication Critical patent/GB9007404D0/en
Publication of GB2230072A publication Critical patent/GB2230072A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
    • E02F3/8858—Submerged units
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F5/00—Dredgers or soil-shifting machines for special purposes
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F5/00—Dredgers or soil-shifting machines for special purposes
    • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
    • E02F5/10—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches with arrangements for reinforcing trenches or ditches; with arrangements for making or assembling conduits or for laying conduits or cables
    • E02F5/104—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches with arrangements for reinforcing trenches or ditches; with arrangements for making or assembling conduits or for laying conduits or cables for burying conduits or cables in trenches under water
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F5/00—Dredgers or soil-shifting machines for special purposes
    • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
    • E02F5/12—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches with equipment for back-filling trenches or ditches
    • E02F5/125—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches with equipment for back-filling trenches or ditches underwater
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L1/00—Laying or reclaiming pipes; Repairing or joining pipes on or under water
    • F16L1/26—Repairing or joining pipes on or under water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation

Abstract

A method of correcting free span in pipeline systems comprises transporting material from a zone on the seabed (2) spaced from the pipeline (1) to the free span area by means of undersea pump means (10). The fill material may be transported to the pipeline (1) through a duct (11) and discharge apparatus (12). The equipment may be suspended from derricks on a surface vessel (Fig. 7 not shown). The equipment may also be used to transport contaminated material from around the legs of offshore structures to be buried in a trench. <IMAGE>

Description

SUBSEA PIPELINE FREE SPAN RECTIFICATION METHOD AND APPARATUS This invention relates to a subsea pipeline free span rectification or correction method and apparatus.
In subsea pipeline systems, the pipeline is laid on the seabed and, in an ideal situation, is supported along the whole of its length in order that the pipeline is not subjected to additional stress. The seabed is made up, amongst other things, of silt in suspension. This silt may be agitated by action of marine life and this, in combination with the water flow, results in the silt being carried away. When this occurs a free span results in the pipeline so that the pipeline is no longer supported along the whole of its length but at spaced points.
Clearly, the unsupported length of the pipeline, or free span, is subjected to additional stresses which may result in damage to the pipeline.
It is an object of the present invention to provide a method and apparatus for correcting the occurrence of free span in subsea pipeline systems.
According to the present invention there is provided a method of correcting free span in pipeline systems comprising transporting material from a zone spaced from the pipeline to the free span area by means of undersea pump means, the fill material being obtained from the seabed.
Preferably the material transportation is via a duct extending between the pump means and the free span. A discharge apparatus may be provided at the end of the duct remote from the pump means.
Preferably, the discharge apparatus and the pump means are separately suspended from a surface vessel and the duct means extends between and is supported by the pump means and discharge apparatus. The surface vessel may also support a remotely operated vehicle (ROV) for monitoring the pipeline system and the transportation and discharge of fill material.
The volume of fill material preferably is sufficient to over-correct the free span so as to leave the pipeline embedded within the fill material.
Further according to the present invention there is provided apparatus for correction of free span in pipeline systems comprising pump means for lifting fill material from the seabed at an area spaced from the pipeline and duct means for conveying said fill material from the pump to discharge apparatus located over the pipeline.
Preferably, the pump and discharge apparatus are controlled from a service vessel.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic view illustrating the occurrence of pipeline free span; Fig. 2 is a sectional view of the situation of Fig. 1; Fig. 3 is a diagrammatic view of apparatus for carrying out the method of the present invention; Fig. 4 is a detailed view of the discharge means of the apparatus for Fig. 3; Fig. 5 is a schematic view illustrating a corrected free span; Fig. 6 is a sectional view of the situation of Fig.
5; and Fig. 7 illustrates the elements of the apparatus of the invention.
Referring to the drawings, a pipeline 1 is laid on the seabed 2 which includes silt 3 in suspension. The silt 3 is liable to agitation by marine life 4. This disturbing of the seabed 2 by the marine life 4 results in the silt in suspension being carried away by water flow.
As can be seen in Fig. 2, a clearance 5 results below the pipeline in the form of a free span, this free span causes extraordinary stresses on the pipeline which may result in damage.
Referring now to Figs. 3 to 6, the present invention provides a method and apparatus for correcting the free span. The apparatus is in the form of a pump 10 which may be pneumatic, hydraulic or electrically driven. The pump 10 collects fill material from the seabed and transports the fill material along a duct 11 to discharge apparatus 12. The pump 10 and discharge apparatus 12 are controlled by a service vessel 20 which moves along the length of the pipeline to effect repair. As is best seen in Fig. 7, the pump 10 is supported by a first derrick 21 on the vessel 20 whilst the discharge apparatus 12 is supported by a second derrick 22. The service vessel 20 may also have an ROV 30 having its own garage 31.
As can be seen in Figs. 5 and 6, the original trench has been filled thus correcting the free span. In addition, the natural seabed materials laid over the pipeline give additional protection and because of the nature of the material no attraction to marine life exists thus prolonging the repair.
Modifications and improvements may be incorporated without departing from the scope of the invention.
The apparatus of the present invention may also be used in the removal of contaminated material which accumulates around the leg members of offshore structures.
This involves the digging of a trench using the pump 10, moving the pump 10 to the location at which the contaminated material exists, that is, adjacent the leg member, positioning a discharge member 12 over the trench and activating the pump to cause the contaminated material to be transported from the base of the leg member into the previously dug trench. The trench may then be filled with the original material thus burying the contaminated material.

Claims (7)

1. A method of correcting free span in pipeline systems, comprising transporting material from a zone spaced from the pipeline to the free span area by means of undersea pump means, the fill material which is transported to the pipeline being obtained from the seabed.
2. A method as claimed in claim 1, wherein the material transportation is via a duct extending between the pump means and the free span.
3. A method as claimed in claim 2, wherein a discharge apparatus is provided at the end of the duct remote from the pump means.
4. A method as claimed in claim 3, wherein the discharge apparatus and the pump means are separately suspended from a surface vessel and the duct means extends between and is supported by the pump means and discharge apparatus.
5. A method as claimed in claim 4, wherein the surface vessel also supports a remotely operated vehicle (ROV) for monitoring the pipeline system and the transportation and discharge of fill material.
6. A method as claimed in any preceding claim, wherein the volume of fill material is sufficient to over-correct the free span so as to leave the pipeline embedded within the fill material.
7. Apparatus for correction of free span in pipeline systems comprising pump means for lifting fill material from the seabed at an area spaced from the pipeline and duct means for conveying said fill material from the pump to discharge apparatus located over the pipeline.
GB9007404A 1989-04-01 1990-04-02 Transporting seabed material Withdrawn GB2230072A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898907411A GB8907411D0 (en) 1989-04-01 1989-04-01 Subsea pipeline free span rectification method and apparatus
GB898907543A GB8907543D0 (en) 1989-04-04 1989-04-04 Subsea pipeline free span rectification method and apparatus

Publications (2)

Publication Number Publication Date
GB9007404D0 GB9007404D0 (en) 1990-05-30
GB2230072A true GB2230072A (en) 1990-10-10

Family

ID=26295165

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9007404A Withdrawn GB2230072A (en) 1989-04-01 1990-04-02 Transporting seabed material

Country Status (1)

Country Link
GB (1) GB2230072A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108317340B (en) * 2018-03-26 2023-03-31 天津大学 Active protection device and method for promoting scouring and preventing submarine pipeline from hanging

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1235790A (en) * 1968-06-17 1971-06-16 Ihc Holland Nv Apparatus for digging in a pipe line or tubes which have been laid on the bottom of a waterway, for example, a seabed
GB2007598A (en) * 1977-10-17 1979-05-23 Selmar A S Ing F Hoyer Ellefse Protection of Sea Bed Installations
GB2222424A (en) * 1988-09-03 1990-03-07 Murray Ian Engineering Ltd Removing material from the seabed by dredging
GB2222425A (en) * 1988-09-03 1990-03-07 Murray Ian Engineering Ltd Dredging system for backfilling

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1235790A (en) * 1968-06-17 1971-06-16 Ihc Holland Nv Apparatus for digging in a pipe line or tubes which have been laid on the bottom of a waterway, for example, a seabed
GB2007598A (en) * 1977-10-17 1979-05-23 Selmar A S Ing F Hoyer Ellefse Protection of Sea Bed Installations
GB2222424A (en) * 1988-09-03 1990-03-07 Murray Ian Engineering Ltd Removing material from the seabed by dredging
GB2222425A (en) * 1988-09-03 1990-03-07 Murray Ian Engineering Ltd Dredging system for backfilling

Also Published As

Publication number Publication date
GB9007404D0 (en) 1990-05-30

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)