WO2005028942A1

WO2005028942A1 - A pipeline apparatus

Info

Publication number: WO2005028942A1
Application number: PCT/IE2004/000129
Authority: WO
Inventors: Ciaran Early; Eric Gage; Daniel Joseph O'sullivan; James Early
Original assignee: Carsphairn Limited
Priority date: 2003-09-23
Filing date: 2004-09-23
Publication date: 2005-03-31
Also published as: IES20030696A2

Abstract

An autonomous pipeline apparatus (100) for use in detecting buckles or deformations of a pipeline (11) during a pipe lay operation. The autonomous pipeline apparatus (100) comprises a vessel having a first end, a second end and an elongate body intermediate the first and second ends, the body of the vessel having an interior and exterior surface. Hydraulic means (5) are positioned within the body of the vessel. The vessel has an attachment piece (7) at the first end and a retaining mechanism (9) positioned along the exterior surface of the elongate body. The retaining mechanism (9) is operable by the hydraulic means (5) to engage with the interior surface of the pipeline (11) and by a battery powered motor (13) for propelling the autonomous pipeline apparatus (100) along the inside of the pipeline (11). The attachment piece is selected from one of a gauging plate (7), an isolation plug (400) or callipers. The gauging plate (7) is used to determine if the pipeline is damage free after being laid.

Description

A PIPELINE APPARATUS

The present invention relates to an apparatus for pipelines and in particular to an autonomous pipeline apparatus with attachments. An autonomous pipeline apparatus is an apparatus of the type which does not require umbilicals to provide a source of motive power for the apparatus.

Offshore oil and gas products are brought to shore via subsea transportation systems which are primarily composed of long lengths of pipe known as pipelines. Various pipe lay operations are conducted to install pipelines on the seabed.

One such operation uses pipe lay barges which crab along the seabed on anchors. Lengths of pipe are welded together to construct pipelines on the barge. The pipeline is laid on the seabed as the barge crabs its way forward. Typical examples of lay barges are Seamac, Castoro 6, Castoro 10, and Tog Mor.

For deeper water, or areas of the seabed that are congested due to the presence of other pipeline networks, lay barges using anchor systems cannot be used. Instead dynamically positioned lay vessels, such as Solitaire, Lorelay and Saipem 7000 which do not require anchors are used.

Other methods of installing pipelines include preparing the pipelines on land and then transferring the prepared pipeline to the desired off-shore location.

One example of this type of operation involves pre-fabricating a collection of various sized pipelines and umbilicals together and containing them within an outer casing on shore. The pipelines and umbilicals together in the outer casing are known as a bundle, examples of bundle operations include Wick or Orkanger. The bundles are pulled into shallow water prior to being towed to the off-shore location. In shallow waters the bundle is suspended under two tug boats and ballasted by chain weights. The bundle is transported to its pre-determined location by towing offshore using a Controlled Depth Towing Method (CDTM).

Alternatively, the- pipeline can be laid from a reel pipelay vessel such as Deep Blue, Skandi Navica 16, Seaway Falcon 16 and Seaway Kestrel 14. Rigid steel pipe up to 18 inches in diameter and 20mm wall thickness can be laid from these types of vessel. The rigid steel pipe is spooled onto the vessels reel at the shore-side pipe base. The vessel then sails to the predetermined off-shore location and the pipe is spooled off the reel through tensioners where it is straightened, before it is over-boarded and laid on the seabed.

If the pipeline length required is longer than the amount on the reel, the lay vessel will return to port, there, additional pipe is spooled onto the reel. The vessel then sails back to the location where the initial pipeline end is recovered. The two pieces of pipe are welded together thereby extending the pipeline. Additional lengths of pipe are added as required.

Generally pipe lay operations are performed by a separate company to the oil or gas company. The pipe lay contractor must deliver a pipeline to the oil or gas company without any buckles or deformations.

Traditionally, on completion of a pipe lay operation, a pipeline tool (a pig) containing a sectored gauging plate is pushed from the start up head of the pipeline with fluid. The gauging plate is sized to approximately 95% of the pipeline internal diameter. When the gauging pig is received at the end of the pipeline, its sectored gauge plate is checked to ensure that it contains no nicks, deformations or bends. If the gauge plate is damage free, the pipeline is accepted as being free of buckles or dents, by the pipeline integrity assessor from the oil or gas company. If the pipeline has buckles or dents the assessor will not accept the pipeline for the oil or gas company, until the impediments are removed.

Removal of a buckle or dent from a laid pipeline may involve enormous time, expense, and risk. The pipeline may have to be recovered to remove the buckled section, this can prove to be extraordinarily difficult especially if the entire pipeline is flooded. Alternatively, the buckled pieces may be cut out and a hyperbarically welded piece is positioned as a replacement.

A number of different solutions have been proposed to provide a more efficient real time method of detecting buckles or dents described for each of the pipe lay operations. During pipe lay from a lay barge or dynamically positioned vessel, a gauging plate can be towed on a fixed line behind and attached to a line up clamp. This gauge plate and its associated strain gauge provide real-time positive indication of pipe buckle, and the damaged pipe can be recovered immediately, resulting in low risk and reduced loss of pipe and time.

Prior to pulling bundles into shallow water the pipeline sections within the bundle are pigged and gauged to ensure that they are buckle free. The protecting outer casing on the bundle then assures the integrity of the encapsulated pipelines within the bundle.

On some vessels it is also possible to detect a break in the pipeline causing water to flood into the pipeline. This is known as a wet buckle. The technology used is known as an "Exit Monitoring System", which constantly reads lay tension. A wet buckle results in an instantaneous increase in weight of pipe from loss of buoyancy hence an increase in the lay tension, this is what the monitoring system records.

Currently there is no method of gauging whilst laying a pipeline to ensure that a rigid reeled pipeline, is buckle free, without filling the pipeline with either liquid or gas.

Furthermore it is not possible to isolate a pipe during pipe lay from a rigid reel vessel, especially if the pipe has a wet buckle. Currently if such an event was to occur loss of the pipeline would be inevitable.

It is an object of the present invention to seek to alleviate the above disadvantages.

Accordingly, the present invention provides an autonomous pipeline apparatus comprising a first end, a second end, an elongate body intermediate the first and second ends, the body having an exterior surface, a hydraulic means disposed on the body, the body having an attachment piece at the first end and a retaining mechanism positioned along the exterior surface of the elongate body, the retaining mechanism being operable by the hydraulic means to be engagable with the interior surface of the pipeline and by a motor for propelling the autonomous pipeline apparatus along the inside of the pipeline.

Ideally, the apparatus includes battery means for operating the motor.

Preferably, the retaining mechanism includes a plurality of wheels to engage with the interior surface of the pipeline. Ideally, the retaining mechanism includes one or more tracks to engage with the interior surface of the pipeline.

Preferably, the retaining means includes a combination of wheels and tracks. Ideally the retaining system comprises a plurality of rubber wheels when the autonomous apparatus is used within a straight pipeline without any alterations in the internal pipeline dimensions.

Alternatively, the retaining system comprises a rubber wheel and track system when the autonomous apparatus is used within a pipeline that has tee pieces or other appurtenances fitted which alter the internal pipeline diameter.

Preferably, the motor comprises one or more battery powered high torque motors.

Ideally, the hydraulic means provides an outward radial force to the pipeline's interior surface via the retaining mechanism causing the retaining mechanism to engage with the interior surface and the one or more motors provide a torque to the retaining mechanism enabling the pipeline apparatus to move at a constant speed within the pipeline. The torque applied by the hydraulic system to the retaining mechanism is dependent on the outward radial force and the diameter of the wheels of the retaining mechanism. Advantageously, the motor speed and torque are easily adjusted using speed reducers and/or adjusting the size of the wheels of the retaining system. If the diameter of the wheels of the retaining system is increased a larger torque is needed, however there are fewer motor rotations as the autonomous pipeline apparatus moves more quickly through the pipeline.

Preferably, the autonomous pipeline apparatus travels through pipeline which is at an inclination of up to 90° relative to the surface of the water.

Ideally, the autonomous pipeline apparatus further comprises a control system, the control system having a remote unit and means for communicating with the remote unit whereby the control system starts and stops the one or more motors by responding to signals from the remote unit. Preferably, the control system and remote unit communicate by means of an isotope wand means.

Ideally, the remote unit is fitted with a first radioactive source.

Preferably, the first radioactive source is Cesium 137.

Ideally, movement of the remote unit is detected using one or more scintillating detectors disposed in the autonomous pipeline apparatus.

Preferably, the autonomous pipeline apparatus further comprises a location detector.

Ideally, the location detector comprises a second radioactive source.

Preferably, the second radioactive source is Iridium 192.

Ideally, the attachment piece comprises a gauging plate.

Preferably, the gauging plate comprises a sectored gauge plate.

Ideally, the attachment piece comprises callipers.

Preferably, the attachment piece comprises an isolation plug.

Ideally, the isolation plug comprises a closed hydraulic system including a piston centrally situated within the isolation plug and a cylindrical vessel with sensors, locking grips, sealing members and a plate member incorporating a master dump valve, the locking grips and sealing members encircling the cylindrical vessel whereby in use when the sensors detect the presence of water a hydraulic pump operates the piston and the locking grips and the sealing members are forced into contact with the interior circumferential surface of the pipe to block and isolate the pipe.

Preferably, the actions of the piston and the sensors are communicable to the control system on the autonomous pipeline apparatus using extremely low frequency magnetic waves. Ideally, the extremely low frequency magnetic waves are detectable and transmittable using an aerial array cluster.

Preferably, the cumulative weight of the vehicle is less than a weight required to overcome the tyre/track friction force acting between the wheel/track and the wall at any pipeline angle of inclination. This enables the autonomous apparatus to grip the interior surface of the pipeline and travel therein whilst maintaining traction.

Ideally, the apparatus is manufactured from lightweight aluminium.

Preferably, the battery power is provided by one or more lithium ion batteries.

Preferably, the battery driven motor comprises a plurality of battery driven high torque electric motors on an open differential. Ideally, power is provided by lithium ion batteries however any suitable power supply known to a person skilled in the art can be used. Preferably, there are four high torque electric motors however the invention is not limited to this number of electric motors.

Conveniently, the autonomous pipeline apparatus moves at a speed of 500 meters per hour.

Accordingly, the present invention also provides a method of detecting buckles and preventing wet buckle in a pipeline being laid by a reeled pipelay vessel comprising the steps of installing an autonomous pipeline apparatus as described above into the head of the pipeline prior to the pipeline being laid, overboarding the head of the pipeline at a desired location and activating the autonomous pipeline apparatus.

Ideally, the method further comprises the- step of moving the autonomous pipeline apparatus through the pipeline at the same speed as the pipeline is being laid.

Preferably, the method further comprises the step of positioning the autonomous pipeline apparatus beneath the surface of the water where it is easily located by a remote unit. Ideally, the method further comprises the step of positioning the autonomous pipeline apparatus between the splash zone and touchdown areas of the sea. The splash zone is defined to be the turbulent area of water at the surface of the sea where the pipeline enters the sea and the touchdown area is defined to be the calmer area at the seabed where the pipeline rests or on which the pipeline rests prior to being burial or trenching. If the pipeline buckles, the apparatus stops as it cannot pass through the buckled area. The remote unit detects that the apparatus has stopped. The buckled section is recovered to the surface for inspection and repair after which pipe laying continues.

Preferably, the method further comprises the step of detecting that the pipeline apparatus has stopped via the remote unit.

Ideally, the method further comprises the step of removing the autonomous pipeline apparatus from the pipeline using a chaser pigging tool in the event of mechanical failure.

Preferably, the method further comprises the step of detecting a wet buckle as a result of ingress of water via isolation plug sensors and activating the isolation plug to seal the pipeline.

Ideally, the method further comprises the step of sealing the pipeline in less than three seconds. Advantageously, the pipeline is then recovered to the surface for repair. Conveniently the isolation plug attachment can be deactivated by activating a master dump valve on the isolation plug.

Ideally, movement of the remote unit is detected using scintillating detectors tuned for frequency recognition of specific radioactive isotopes disposed in the autonomous pipeline apparatus. Preferably, if the remote unit approaches in a first direction, for example from left to right, the scintillating detectors detect the direction of the movement, the control system switches the autonomous pipeline apparatus on and the autonomous pipeline apparatus moves in the pipeline. If the remote unit moves in a second direction which is opposite to the first direction, the control system switches the autonomous pipeline apparatus off and movement stops.

Ideally, the control system is housed in a pod on the- body of the autonomous pipeline apparatus. Advantageously, the autonomous pipeline apparatus is made from light weight materials so that the cumulative weight of the apparatus is less than the wheel co-efficient of the function forcing the apparatus to move within the pipeline. Ideally, the materials used include aluminium 6082 or 6A14V. The materials are not limited to these materials and any appropriate material known to a person skilled in the art can be used.

Advantageously, the autonomous pipeline apparatus of the invention is readily adapted to fit pipelines with different internal diameters.

Advantageously, the gauge plate comprises a sectored gauge plate which is sized to meet specific customer requirements. Preferably, the gauge plate is made from light weight aluminium, for example aluminium 6082.

If either the gauge plate or the callipers are attached to the vessel and if the apparatus reaches the end of the pipeline on completion of pipe lay without a damaged gauge plate or callipers the pipeline has been laid without damage and is free from impediments. Therefore the pipeline can be laid and tested to be buckle free without filling the pipeline with either liquid or gas.

The invention will now be described more particularly with reference to the accompanying drawings, which show by way of example only, two embodiments of an autonomous pipeline apparatus of the invention.

In the drawings: -

Figure 1 is a plan view of a first embodiment of the apparatus of the invention with a gauge plate attachment;

Figure 1 a is a perspective view from a first side of the first embodiment of the apparatus of the invention with a gauge plate attachment;

Figure 1b is a perspective view from a second side of the first embodiment of the apparatus of the invention with a gauge plate attachment; Figure 2 is a plan view of the first embodiment of the apparatus of the invention in position in an inclined pipeline with a gauge plate attachment;

Figure 3 is a plan view of the first embodiment of the invention in position in a vertical pipeline with a gauge plate attachment;

Figure 4 is a plan view of a second embodiment of the apparatus of the invention with an isolation plug attachment;

Figure 5 is a plan view of the second embodiment of the apparatus of the invention with an isolation plug attachment in an inactivated state in a pipeline; and

Figure 6 is a plan view of the second embodiment of the apparatus of the invention with an isolation plug attachment in an activated state in the pipeline.

Referring initially to Figures 1 to 3 there is shown a first embodiment of an autonomous pipeline apparatus 100 with a gauge plate attachment 7. The apparatus 100 uses onboard lithium ion batteries 1 to drive four high torque electric motors 13 on open differential, which provide propulsion to wheels/tracks 9 to move the apparatus inside a pipeline 11 at a constant speed of approximately 500 metres per hour.

The autonomous pipeline apparatus 100 has a hydraulic system 5 which pushes the rubber wheels/tracks (Figures 1 , 1a, 1b and 2, 9) or rubber wheels (Figure 3, 109) onto the internal surface of the pipeline 11 regardless of the orientation of the apparatus 100. The hydraulic system 5 and rubber wheel/track system (Figures 1, 1a, 1b and 2, 9) or rubber wheels (Figure 3, 109) therefore enable the apparatus 100 to travel up inside steel pipelines 1 maintaining traction and without slipping. The pipeline 11 can be positioned at any angle between 0° to 90° relative to the horizontal. The wheel/tracks 9, 109 encircle the vessel so that wheel/tracks 9, 109 are in contact with the interior circumferential surface of the pipeline 11.

The apparatus 100 is configured so that the cumulative weight of the apparatus 100 is less than a weight required to overcome the tyre/track co-efficient of friction forcing it onto the pipeline- wall 11 enabling, the apparatus to progress up the pipeline wall at an inclination of up to 90°. The gauge plate 7 can be sized to meet customer requirements for 95% of the pipeline internal diameter or as per the pipe lay specification in use.

The control system 3 switching is activated and de-activated by scintillating detectors (not shown) which start and stop the motor 13.

The autonomous pipeline apparatus scintillating detector control switching system works on the Isotope wand principle. The scintillating detectors are tuned to 662 KeV (the resonating frequency for Cesium 137). The remote unit (not shown) located outside the pipeline is fitted with a Cesium 137 source. When the remote unit approaches left to right the scintillating detectors detect this and switch on the motor 13 inside the pipeline 11 which drives the apparatus 100. When the remote unit approaches right to left, the scintillating detectors switch the motor 13 off which stops the apparatus 100.

The apparatus 100, 200 is also fitted with a radioactive source 15, see Figure 3. This is Iridium 192 which resonates at 317 and 468 KeV, which are different KeV frequencies to Cesium 137 and therefore do not affect the on/off control system of the scintillating detectors tuned to the frequency of the Cesium 137 source. The purpose of this Iridium 192 source is to detect the location of the apparatus 100 under failure conditions.

The Iridium 192 source on the apparatus 100 is detectable by the remote unit which is fitted with a scintillating detector tuned to 317 and 468 KeV.

The control pod 3 on the apparatus 100 has dedicated suitable software to reliably control all functions of the movement of the apparatus 100.

The scintillating detectors mounted on the remote unit are tuned to enable the remote unit to quickly detect the presence of the apparatus 100 inside the pipeline against normal background radiation.

In use the apparatus 100 is installed inside the pipeline lay down head prior to the lay down head being installed. The apparatus 100 is activated to crawl through the pipeline 11 , as the lay down head is overboarded so that the apparatus 100 takes- up a position beyond the- splash zone where- its location can be easily identified by the- remote uni The apparatus 100 maintains the same speed as the pipe lay and should the pipe lay be too slow the apparatus 100 is stopped. The velocity of the apparatus 100 is always configured to meet maximum vessel pipe lay speeds.

If a buckle is detected by the gauge plate 7 then the apparatus 100 will stop as it cannot pass. If the remote unit detects that the apparatus 100 has stopped, then the remote unit investigates. The buckled section is recovered to surface for inspection and/if required repair.

If the apparatus 100 reaches the end of the pipeline 11 on completion of pipe lay without a damaged gauge plate 7 the line has been laid unbuckled.

In the event that the apparatus 100 has a mechanical breakdown during its gauging operation then the apparatus 100 is pigged out of the line by using a chaser pig.

Referring to Figures 4 to 6 there is shown a second embodiment of the autonomous pipeline apparatus 300 with an isolation plug attachment 400. The autonomous pipeline apparatus 300 operates as previously described however the tracking system 140 comprises a plurality of wheels 110 attached to the body of the autonomous pipeline apparatus 300 by means of spring 111. Furthermore, in this second embodiment of the autonomous pipeline apparatus 300 the control system is housed in a control pod 203 intermediate the autonomous pipeline apparatus 300 and the isolation plug 400.

The isolation plug attachment 400 comprises a closed hydraulic system (not shown), sensors 134 and a packer seal 132, a grip bearing ring 133, a grip segment 131 and wheels 130a, 130b. The closed hydraulic system is centrally situated within the isolation plug attachment 400. Figures 5 and 6 provide views of the isolation plug attachment 400 in an unset and fully set configuration within the interior of an inclined pipeline. In Figure 5 the isolation plug attachment 400 is in an unset configuration and when sensors 134 detect the presence of water a signal is sent to the control system using extra low frequency technology and the piston within the closed hydraulic system is activated. The grip segment 131 which encircles the hydraulic system is forced into contact with the interior circumferential surface of the pipe wail 11. Further activation of the piston causes the packer seal 132. into contact with the interior circumferential ofthe pipe wall 11. The buckled section is recovered to the surface for inspection and/if required repair. The isolation plug is disengaged by releasing the master dump valve (not shown). In the event that the autonomous pipeline apparatus 300 has a mechanical breakdown during its isolation operation, then as before the apparatus 300 is pigged out of the line, by using a chaser pig.

It will of course be understood that the invention is not limited to the specific details herein described, which are given by way of example only and that various alterations and modifications may be made without departing from the scope of the invention.

Claims

CLAIMS:

1. An autonomous pipeline apparatus (100) comprising a first end, a second end, an elongate body intermediate the first and second ends, the body having an exterior surface, a hydraulic means (5) disposed on the body, the apparatus having an attachment piece at the first end and a retaining mechanism (9) positioned along the exterior surface of the elongate body, the retaining mechanism (9) being operable by the hydraulic means (5) to be engagable with the interior surface of the pipeline (11) and by a motor (13) for propelling the autonomous pipeline apparatus along the inside of the pipeline (11).

2. An autonomous pipeline apparatus as claimed in Claim 1 , wherein the apparatus includes battery means for operating the motor (13).

3. An autonomous pipeline apparatus as claimed in Claim 1 or Claim 2, wherein the retaining mechanism (19) includes a plurality of wheels (110) to engage with the interior surface of the pipeline.

4. An autonomous pipeline apparatus as claimed in any one of the preceding claims, wherein the retaining mechanism (9) includes one or more tracks (140) to engage with the interior surface of the pipeline.

5. An autonomous pipeline apparatus as claimed in claim 2, wherein the motor comprises one or more battery powered high torque motors.

6. An autonomous pipeline apparatus as claimed in any one of the preceding claims, wherein the hydraulic means (5) provides an outward radial force to the pipelines interior surface (11) via the retaining mechanism (9) causing the retaining mechanism to engage with the interior surface and the one or more motors (13) provide a torque to the retaining mechanism (9) enabling the pipeline apparatus (100) to move at a constant speed within the pipeline.

7. An autonomous pipeline apparatus as claimed in any one of the preceding claims, which is adapted to travel through a pipeline which is at an inclination of up to 90° relative to the surface- of the water.

8. An autonomous pipeline apparatus as claimed in any one of the preceding claims, wherein the autonomous pipeline apparatus further comprises a control system, the control system having a remote unit and means for communicating with the remote unit (3) whereby the control system starts and stops the or each motor by responding to signals from the remote unit.

9. An autonomous pipeline apparatus as claimed in Claim 8, wherein the control system and remote unit communicate by means of an isotope wand means.

10. An autonomous pipeline apparatus as claimed in any one of Claim 8 or Claim 9, wherein the remote unit is fitted with a first radioactive source.

11. An autonomous pipeline apparatus as claimed in Claim 10, wherein the first radioactive source is Cesium 137.

12. An autonomous pipeline apparatus as claimed in any one of Claim 8 to Claim 11 , whereby movement of the remote unit is detected using one or more scintillating detectors disposed in the autonomous pipeline apparatus.

13. An autonomous pipeline apparatus as claimed in any one of the preceding claims, wherein the autonomous pipeline apparatus further comprises a location detector (15).

14. An autonomous pipeline apparatus as claimed in Claim 13, wherein the location detector comprises a second radioactive source.

15. An autonomous pipeline apparatus as claimed in Claim 14, wherein the second radioactive source is Iridium 192.

16. An autonomous pipeline apparatus as claimed in any one of the preceding claims, wherein the attachment piece comprises a gauging plate (7).

17. An autonomous pipeline apparatus as claimed in Claim 16, wherein the gauging plate comprises a sectored gauge plate.

18. An autonomous pipeline apparatus as claimed in any one of Claim 1 to Claim 15, wherein the attachment piece comprises callipers.

19. An autonomous pipeline apparatus as claimed in any one of Claim 1 to Claim 15, wherein the attachment piece comprises an isolation plug (400).

20. An autonomous pipeline apparatus as claimed in Claim 19, wherein the isolation plug (400) comprises a closed hydraulic system including a piston centrally situated within the isolation plug and a cylindrical vessel with sensors (134), locking grips (131), sealing members (132) and a plate member (133) incorporating a master dump valve, the locking grips and sealing members encircling the cylindrical vessel whereby in use when the sensors detect the presence of water a hydraulic pump operates the piston and the locking grips and the sealing members are forced into contact with the interior circumferential surface of the pipe to block and isolate the pipe.

21. An autonomous pipeline apparatus as claimed in Claim 20, wherein the actions of the piston and the sensors are communicable to the control system on the autonomous pipeline apparatus using extremely low frequency magnetic waves.

22. An autonomous pipeline apparatus as claimed in Claim 21 , wherein the extremely low frequency magnetic waves are detectable and transmittable using an aerial array cluster.

23. An autonomous pipeline apparatus as claimed in any one of claim 3 to claim 22, wherein the cumulative weight of the apparatus is less than a weight required to overcome the tyre/track friction force acting between the wheel/track and the wall at any pipeline angle of inclination.

24. An autonomous pipeline apparatus as claimed in any one of the preceding claims, wherein the apparatus is manufactured from lightweight aluminium.

25. An autonomous pipeline apparatus as claimed in Claim 2, wherein the battery power is provided by one or more lithium ion batteries.

26. A method of detecting buckles and preventing wet buckle in a pipeline being laid by a reeled pipelay vessel comprising the steps of installing an autonomous pipeline apparatus (100) as claimed in any one of the preceding claims into the head of the pipeline prior to the pipeline being laid, overboarding the head of the pipeline at a desired location and activating the autonomous pipeline apparatus.

27. A method as claimed in Claim 26, further comprising the step of moving the autonomous pipeline apparatus through the pipeline at the same speed as the pipeline is being laid.

28. A method as claimed in Claim 26 or Claim 27, further comprising the step of positioning the autonomous pipeline apparatus beneath the surface of the water where it is easily located by a remote unit.

29. A method as claimed in Claim 28, further comprising the step of positioning the autonomous pipeline apparatus between the splash zone and touchdown areas of the sea.

30. A method as claimed in any one of Claim 26 to Claim 29, further comprising the step of detecting that the pipeline apparatus has stopped via the remote unit.

31. A method as claimed in any one of Claim 26 to Claim 30, further comprising the step of removing the autonomous pipeline apparatus from the pipeline using a chaser pigging tool in the event of mechanical failure.

32. A method as claimed in any one of Claim 26 to Claim 31 , further comprising the step of detecting a wet buckle as a result of ingress of water via isolation plug sensors (134) and activating the isolation plug (400) to seal the pipeline.

33. An autonomous pipeline apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

34. A method of detecting buckles and preventing wet buckle in a pipeline being laid by a reeled pipelay vessel substantially as hereinbefore described with reference to the accompanying drawings.