Classifications

• • 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
  • F16L1/12—Laying or reclaiming pipes on or under water
  • F16L1/16—Laying or reclaiming pipes on or under water on the bottom
  • F16L1/163—Laying or reclaiming pipes on or under water on the bottom by varying the apparent weight of the pipe during the laying operation

Definitions

• the present invention relates to offshore flowlines, particularly to the
• Flowlines are used for handling fluids to or from an offshore well or
• flowline is intended to refer
• Risers are a grouping of flowline, pipeline or riser, including catenary risers.
• umbilical cables may be deployed with the flowlines and may be included as part
• the bundle comprises a steel carrier pipe which provides
• flowline within a carrier pipe bundle may be towed offshore.
• the carrier pipe which is typically about 1 metre in diameter, has walls of
• the carrier remains on or just above the seabed, serving as a protective casing for the
• An object of the present invention is to provide a flowline delivery system
• flowline is to be understood to refer to a pipeline or other
• means for handling fluids may refer to a single flowline or a bundle.
• the carrier pipe may be made of any suitable material. Preferably it is of a
• buoyancy Preferably, it is made of plastics, for example polyethylene.
• the carrier pipe may be of substantially the same length as the flowline, or it may
• the carrier pipe is of substantially continuous elongate cross section which
• the pipe is of substantially continuous elongate cross section along at
• the fluid may be liquid or gaseous.
• the fluid is a hydrocarbon.
• the fluid may be a gas such as air or
• the carrier pipe may be attached to the flowline via any suitable means.
• the flowline may be suspended from the carrier pipe by a plurality of chains
• the chains include a release bar or
• the flowline may be attached to the carrier
• the beam includes a protruding surface for attachment of
• the flowline is releasably attached to the
• a plurality of carrier pipes may be
• the fluid is expelled from the carrier pipe at the underwater
• the fluid expelled from the carrier pipe is preferably displaced by
• the fluid from the carrier pipe is recovered. More preferably,
• the fluid is recovered to sea level, for example to a tanker or other storage device
• the fluid is
• the fluid may be driven out of the carrier pipe to sea level via a conduit.
• conduit is connected to the carrier pipe by a sealable valve.
• the fluid may be expelled from the carrier pipe into the
• the expelled fluid is preferably a gas.
• the expelled gas may be released via
• the carrier pipe preferably
• Said means may comprise a movable member such as a piston, for
• said means may include a membrane interface
• Said means may be located at an end region of the seawater and the fluid. Said means may be located at an end region of the seawater and the fluid. Said means may be located at an end region of the seawater and the fluid.
• the flowline may include a cavity
• the fluid in the flowline cavity is
• a gas Preferably it is released into the seawater upon flooding.
• the above method further includes the step of flooding the
• fluid may be released from the carrier pipe into a tanker or other storage device or
• the flowline may itself have sufficient ballast to remain at or
• the flowline may, for example, be
• it may have a cavity which is preflooded prior to towing.
• the method of the invention may further include the steps of:
• the fluid therein may be
• the carrier pipe and flowline are towed to an offshore site prior to charging the carrier pipe with a fluid
• the fluid is also recovered.
• ballast line there are two carrier pipes, one of which acts as a ballast line.
• the method of the invention comprises the steps of:
• the fluid having a specific gravity lower than
• the carrier pipe being flooded with seawater via the ballast line, and detaching and
• the carrier pipe includes means for balancing internal fluid
• ballast line also includes such means.
• Concrete has the advantage of providing physical protection and stability.
• Figure 1 is a schematic view of a sequence of steps according to a
• Figure 2 is a cross-sectional view of a method of recovering the fluid from
• the carrier pipe which may be used in conjunction with a method according to the
• Figure 3 is a schematic view of a sequence of steps according to a second
• Figure 4 is a schematic view of a sequence of steps according to a third
• Figure 5 is a cross-sectional view of a possible sequence of steps for
• Figure 6 is a perspective view of a releasable attachment means according
• Figure 7 is a cross-sectional view of a further releasable attachment means
• Figure 8 is a side view of the releasable attachment means depicted in Figure 7.
• Figure 9 is a schematic view of a sequence of steps according to a fourth specific
• a flowline 1 is
• Chains 4 are suspended from the flowline along its length to provide
• carrier pipe and bundle are laid on the seabed 8 from a shallow water laybarge in a
• the carrier pipe at this stage contains seawater.
• a tanker 7 is then connected to the carrier pipe 2 via a hose 5.
• Kerosene is
• Fig. lb shows the step of displacing seawater by kerosene and the resultant increase in buoyancy of the carrier pipe.
• Fig. lc the entire carrier
• pipe 2 is flooded with kerosene, providing sufficient buoyancy for the pipe and
• buoyancy for towing is achieved, as shown in Fig lc, the carrier is connected to a
• the trailing end of the carrier pipe is connected to trail tug 9 to facilitate
• tanker 7 is connected via a hose 5 to the carrier pipe 2 for recovery of the
• the carrier pipe may be provided with two pigs located near each end of the carrier
• the driving pressure is equal to the pressure difference
• Chains 4 are suspended from the flowline along its length to provide
• the carrier pipe 2 contains air and is sufficiently buoyant to float at
• Kerosene is then delivered from a tanker
• buoyancy for off-bottom towing is achieved, as shown in Fig. 3 c, the carrier is
• tanker 7 is connected via a hose 5 to the carrier pipe 2 for recovery of the
• the carrier pipe is gradually flooded with seawater as the kerosene is
• Fig 3f shows the gradual shift of the carrier pipe towards
• pipe is made of polyethylene, this provides sufficient buoyancy for the pipe to lift
• FIG. 4 shows schematically yet a further method of the invention.
• flowline 1 is suspended from a polyethylene carrier pipe 2 by straps 53.
• the carrier pipe and flowline assembly is then towed to the desired offshore site
• the cord 402 may be made of any suitable material, and may for example be a wire or rope.
• a flooding line 404 is
• the flowline may be allowed
• seawater causes the pig to be forced along the flowline cavity pushing against the
• the flowline is then laid on the seabed 8 in the desired location, monitored
• the carrier pipe 2 is also flooded with
• flowline assembly is towed at or near the surface of the sea. This allows the use
• vessels which are less costly, not necessarily being vessels specifically for pipe-laying, this being of particular advantage in more remote areas.
• FIG. 4 shows a method of a preferred method of the invention
• the clump weight 403 may be dispensed
• the flowline is flooded over a length sufficient to create a
• FIG. 4 may be modified by use of a flowline which need not be
• the flowline may, for example, itself be sufficiently dense to remain at or
• Fig. 5a shows the flowline 1
• the flowline 1 is shown here as a bundle having two separate lines 38 and 39, but other variants including a
• the carrier pipe is filled with kerosene 31 and is buoyant
• the carrier pipe 2 is flooded with seawater 32 thereby reducing its buoyancy level.
• Fig. 6 shows an alternative system for releasably attaching a carrier pipe to
• carrier pipes 2 are connected together. Each carrier pipe 2 bears an I-shaped
• a flowline 1 is attached to each of the beams 61 via a
• FIGs. 7 and 8 show a further alternative system for releasably attaching a
• a carrier pipe 2 bears a lug 51 provided with eyes 52 through which passes a Kevlar strap 53.
• the strap circumscribes the
• a plurality of straps 53 are provided at intervals along
• the release pin 54 secures the strap 53 by passing through a terminal loop
• the flowline 1 is flooded with seawater 100 and the system settles at or near
• Detachment is effected by withdrawal of the release pin 54 from the eye
• control wire 58 which is connected to each release wire and
• FIG. 9 shows a further method of a method according to the invention. Referring
• flowline 1 is releasably attached to carrier pipe 2 and ballast line 900,
• ballast line are ballasted as necessary with seawater for surface towing.
• the carrier pipe is then linked to a tanker 902 at the offshore site, as shown
• ballast line 900 is
• ballast line 900 As
• the ballast line 900 also includes a pig 906 as an interface
• the ballast line 900 The ballast line 900
• ballast line as shown in Fig 9d.
• the displaced fluid 904 is forced by the seawater
• the flowline 1 is also progressively filled with seawater, and
• the assembly begins to settle at one end on the seabed 8, guided to the desired
• Fig. 9 shows the flowline 1, carrier pipe 2 and ballast line
• ballast line 900 The attachment means 908 is towed back to shore by tug 909
• seawater is used to displace the kerosene
• the tanker (902) can be connected to

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Loading And Unloading Of Fuel Tanks Or Ships (AREA)

Applications Claiming Priority (9)

Publications (1)

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Country Status (2)

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• 2002
  • 2002-06-26 WO PCT/GB2002/002934 patent/WO2003002848A1/en not_active Application Discontinuation
  • 2002-06-26 EP EP02743385A patent/EP1402148A1/de not_active Withdrawn

Non-Patent Citations (1)

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