WO2001086074A1 - Dispositif et procede servant a retirer des plates-formes de forage en mer - Google Patents

Dispositif et procede servant a retirer des plates-formes de forage en mer Download PDF

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Publication number
WO2001086074A1
WO2001086074A1 PCT/DE2001/001752 DE0101752W WO0186074A1 WO 2001086074 A1 WO2001086074 A1 WO 2001086074A1 DE 0101752 W DE0101752 W DE 0101752W WO 0186074 A1 WO0186074 A1 WO 0186074A1
Authority
WO
WIPO (PCT)
Prior art keywords
lifting
cylinders
platform
substructure
pulling
Prior art date
Application number
PCT/DE2001/001752
Other languages
German (de)
English (en)
Inventor
Marten Fluks
Theo Frans Henri Werners
Marinus Wilhelmus Cornelis Maria Van Den Oetelaar
Original Assignee
Mannesmann Rexroth Ag
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
Application filed by Mannesmann Rexroth Ag filed Critical Mannesmann Rexroth Ag
Priority to AU73869/01A priority Critical patent/AU7386901A/en
Priority to DE10191831T priority patent/DE10191831D2/de
Publication of WO2001086074A1 publication Critical patent/WO2001086074A1/fr

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B17/04—Equipment specially adapted for raising, lowering, or immobilising the working platform relative to the supporting construction
    • E02B17/08—Equipment specially adapted for raising, lowering, or immobilising the working platform relative to the supporting construction for raising or lowering
    • E02B17/0809—Equipment specially adapted for raising, lowering, or immobilising the working platform relative to the supporting construction for raising or lowering the equipment being hydraulically actuated
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B2017/0052—Removal or dismantling of offshore structures from their offshore location

Definitions

  • stationary systems For the exploration and extraction of hydrocarbons stored under the sea floor, such as oil and natural gas, stationary systems are used, which have a jacket and a platform.
  • the jacket is a construction that rests on the sea floor and on which the platform is attached.
  • the platform contains the equipment and systems with which the exploration, extraction and extraction are carried out.
  • Platform and jacket occur in the transition phase between the situation in which the platform is already being carried to a large extent by the ship and only partially by the jacket, and the situation in the . the platform is completely lifted off the jacket. If the forces on the ship are unfavorably distributed, stability and seaworthiness can be severely impaired.
  • Fig. 1 there is a platform 1 on a jacket 2 in the sea.
  • two side sections 3a and 3b of a ship are now arranged below end sections of the platform.
  • At least two lifting cylinders 4a and 4b are located on the side sections 3a and 3b of the ship. These lifting cylinders 4a, 4b are connected to hydropneumatic accumulators and act as preloaded springs in the loaded state.
  • the lifting cylinders 4a, 4b are extended into a position in which the cylinder rods of the lifting cylinders touch the underside of the platform 1.
  • the lifting cylinders 4a, 4b act due to their spring action in such a way that the end portions of the cylinder rods, despite the wave movement of the sea, the platform
  • Adjustment of the ballast situation of the ship. 1 and 2 must be completed at a time when the total load on the lifting cylinders 4a, 4b is less than the weight of the platform 1 and a compressive force still acts on the jacket 2.
  • the platform upper part the unit consisting of the platform and the upper section 21 of the jacket being referred to below as the platform upper part.
  • the upper section 21 of the jacket is detached from the lower section of the jacket.
  • the lower section of the jacket is referred to below as the substructure 22.
  • the platform upper part and the substructure 22 can for example by tie rods 23a, 23b, as shown in FIG. 3.
  • the legs of the jacket are divided in such a way that a cutting line 24 runs between the base 22 and the upper section 21 of the jacket.
  • support elements 21a, 21b, 22a, 22b are provided near the cutting line 24, which are preferably designed in a triangular shape.
  • the tension rods are fastened to the sections of the support elements which are distant from the upper section 21 or substructure 22 in such a way that a support element 21a, 21b of the upper section 21 from the jacket is connected to a support element 22a, 22b from the substructure 22.
  • the connection between the support elements and the tension rods takes place on one side of the tension rods via a quick release device, e.g. Detonating bolts 24a, 24b in FIG. 3.
  • a force is generated in the hydraulic lifting cylinders (4a, 4b) which is greater than the weight of the platform upper part.
  • a tensile force thus acts on the tension rods.
  • the forces transmitted from the lifting cylinders to the platform are set in such a way that an estimated total mass of the upper platform part and the estimated position of the center of gravity are taken into account by this. Since the actual values deviate from the estimated values, there are negative effects on the heeling and the trim of the ship after lifting off the platform. This is particularly noticeable when catamaran semi-submersibles are used.
  • the lifting process begins with the detonating bolts being triggered. The ship rises from the water.
  • the lifting cylinders continue to extend due to the pressure conditions in the hydropneumatic accumulator until a state of equilibrium is reached between the forces on the lifting cylinders and the weight of the platform upper part. Due to the complete separation of the platform upper part from the substructure and due to the distance between the platform upper part and the substructure, the platform upper part and the ship can move as a unit. The disadvantage in this case is that the movements of the upper part of the platform and the ship cannot be controlled during the lifting process.
  • the invention has for its object to provide a method and an apparatus for lifting an upper part from a substructure of an offshore platform, by means of which a controlled lifting of the upper part of the platform is possible even under unfavorable environmental conditions, such as strong wind or sea conditions.
  • the upper part and the substructure are connected to one another by controllable pulling devices during the lifting process.
  • the stroke submissions are controlled in such a way that the lifting force applied exceeds the weight of the upper part and the pulling devices are loaded under tension. That is, , the top is practical between the Clamping and pulling devices clamped.
  • the center of gravity and the weight of the upper part can then be determined from the resulting loads on the lifting and pulling devices, so that a defined position of the upper part can be set by suitable control of the lifting and / or pulling devices. This is also possible when the sea is comparatively strong or windy.
  • the effective length of the pulling devices is increased and thus the transmitted pulling force is reduced so that the upper part lifts off the substructure in a controlled manner.
  • the advantage of the solution according to the invention is that not only is the upper part held in a controlled position by the pulling and lifting devices during the entire load transmission phase, and that a stable equilibrium position is ensured even under unfavorable environmental conditions, but especially in that by a controlled movement the towing equipment enables controlled lifting.
  • the pulling devices are only decoupled when the upper part is stably supported on the lifting devices.
  • the lifting devices are formed by hydraulically actuated lifting cylinders which are prestressed in the lifting direction by means of a pressure accumulator, preferably a hydropneumatic accumulator.
  • the traction devices are also preferably formed by hydraulically actuated traction cylinders, with in a preferred embodiment each leg of the platform being assigned two traction cylinders arranged diametrically to one another. It is also possible to arrange more than two pull cylinders per leg.
  • an unlockable check valve is arranged between each pressure accumulator and the lifting cylinder, so that retraction of the lifting cylinder is reliably prevented during the lifting process.
  • FIG. 1 shows a schematic representation of a platform mounted on a jacket in the sea according to the prior art
  • FIG. 2 shows the basic structure of a ship with lifting cylinders according to the prior art
  • FIG. 3 shows a device according to the prior art
  • Figure 4 shows a device according to the present invention
  • Figures 5a and 5b show the forces acting on the platform.
  • the structure of an offshore platform according to the present invention corresponds in essence to the structure shown in FIGS. 1 and 2.
  • the tension rods from FIG. 3 are replaced by tension cylinders 33a, 33b.
  • These pull cylinders 33a, 33b are, as shown in FIG. 4, fastened to support elements 21a, 21b and 22a, 22b.
  • a pulling force is exerted via these pulling cylinders, which acts between the upper part 21 and the substructure 22.
  • the attachment to the support elements 22a, 22b takes place in the same way as in FIG. 3 via quick release mechanisms, for example explosive bolts, via which the pull cylinders 33a, 33b can be decoupled from the substructure 22.
  • Cylinder spaces 34a, 34b and annular spaces 35a, 35b of the traction cylinders 33a, 33b can be connected to a pressure medium source (pump) or a tank, so that pressure medium can be supplied or removed in order to extend or retract the cylinders and thus the acting tensile forces depending to control the lifting force of the lifting cylinders 4a, 4b, the weight and center of gravity of the upper part 21 and the external forces (rough sea, wind, ship movements).
  • a pressure medium source pump
  • a tank so that pressure medium can be supplied or removed in order to extend or retract the cylinders and thus the acting tensile forces depending to control the lifting force of the lifting cylinders 4a, 4b, the weight and center of gravity of the upper part 21 and the external forces (rough sea, wind, ship movements).
  • the lifting cylinders 4a, 4b shown in FIG. 2 for lifting the upper platform part which are also used in the exemplary embodiment according to the invention in accordance with FIG. 4, must be designed such that they can support the upper platform part plus the tensile force applied by the pulling cylinders 33a, 33b, whereby disturbances are taken into account over a tolerance range.
  • a force must be absorbed by the pull cylinders 33a, 33b, which overall is substantially less than the weight of the upper part 22, so that this fact must be taken into account when designing the pull cylinders with a view to saving costs.
  • the side sections 3a and 3b of the ship are brought into the position shown in FIG. 2 with respect to the platform 1 and the Lift cylinder 4a, 4b extended so that lifting forces are transmitted to the upper part.
  • the lifting cylinders 4a, 4b are biased against the platform 1 due to the spring action of the or the associated hydropneumatic reservoir, even in rough seas. Due to the gradual increase in gas pressure in the hydropneumatic accumulators connected to the lifting cylinders 4a and 4b and the consequent increase in pressure in each lifting cylinder 4a, 4b, an increasing part of the weight of the platform 1 becomes from the legs of the jacket 2 to the lifting cylinders 4a, 4b and thus transmitted to the ship. This also requires a simultaneous adaptation of the ship's ballast situation.
  • This load transmission phase is carried out until the lifting cylinders 4 deliver a total force which exceeds the weight of that of the upper part 21 and thus the cylinders 33 pass from the originally unloaded state into a tensile stress phase.
  • the pressures in all cylinders can now be measured using pressure transducers attached to the cylinders. In this way, results are obtained even when the sea is rough, which allows the weight of the upper part 21 and its center of gravity to be determined.
  • load cells or the like can also be used. measure the forces on the cylinders to determine the weight and location of the center of gravity.
  • the determination of the weight and position of the center of gravity takes place at a time when the platform upper part is still connected to the substructure via the closing cylinders 33a, 33b.
  • the pressures are measured in all Lift cylinders and pull cylinders at the same time and not only at one point in time, but practically for a longer time, so that a larger amount of data is available in order to obtain correct mean values of the measured lifting and pressure forces.
  • FIG. 5 a shows a greatly simplified plan view of the platform, the lifting forces applied by the lifting cylinders 4a, 4b being designated by Fc, while the tensile forces applied by the pulling cylinders 33a, 33b are identified by Ft.
  • the larger circles shown hatched each represent a section through a leg 21, 22 of the platform.
  • the larger unshaded circles represent the points of attack of the lifting cylinders 4a, 4b, while the smaller unshaded circles indicate the points of attack of the pull cylinders 33a, 33b.
  • four lifting cylinders are provided in the model shown in FIG. 5a, by means of which the upper part 21 is supported.
  • the substructure is supported on the seabed by four legs. Each of the legs are assigned two pull cylinders 33, so that the upper part
  • the result of the pressure / force determinations in the course of the load transmission phase is shown in dash-dot lines in FIG. 5a in a greatly simplified form. Accordingly, the resulting lifting cylinder force Fc does not lie in the middle between the points of application of the lifting cylinders, but in the illustrated embodiment is displaced to the bottom right, while the resulting tensile force Ft is displaced somewhat to the top left in the load transmission phase. The resulting tensile and compressive forces are connected by the dash-dotted line. 5a, the lifting force Fc moves towards the viewer, while the pulling force Ft is directed downwards away from the viewer.
  • FIG. 5b shows the resulting forces with their respective calculated positions. That is, , The pulling force Ft is removed with a (still unknown) lever arm b from the weight of the upper part, while the resulting lifting force Fc has a (known) lever arm with respect to the pulling force Ft.
  • the calculated weight and position of the center of gravity is now used to calculate and set target values for the cylinder forces of the lifting cylinders 4a, 4b, by means of which a uniform lifting of the platform upper part can be ensured and an undesired heeling and change of the trim can be prevented.
  • the pressures in the memories of the lifting cylinders 4a, 4b are adjusted accordingly to the to generate calculated cylinder forces within a certain tolerance range.
  • the pressure conditions in the pull cylinders 33a, 33b also change, so that the ballast situation of the ship must also be checked and adjusted if necessary.
  • the load distribution on the platform can also be adapted to the relevant requirements.
  • the weight and position of the center of gravity of the upper platform part must be determined again. The entire process is controlled, while the upper platform part is still mechanically connected to the substructure.
  • the load transfer phase is complete.
  • the upper part 21 wants to lift through the set lifting forces, but this is prevented by the pull cylinder 33. These are then controlled in such a way that they extend in a controlled manner and the upper part 21 is lifted off the jacket leg 22.
  • the explosive bolts 24a, 24b or other quick release devices are triggered, whereby the platform upper part can be moved independently of the substructure and moves with the ship. After proper seaworthy attachment of the platform upper part to the ship, the overseas transport can take place.
  • the traction cylinders from FIG. 4 are replaced by pressure cylinders which absorb the tensile forces between the substructure and the upper platform part in the form of compressive forces.
  • the other structure and function of the device of the second Embodiment essentially corresponds to that of the first embodiment, so that a detailed description can be omitted.
  • a releasable check valve is provided in the device according to the first exemplary embodiment between the hydropneumatic reservoir and the lifting cylinders 4a, 4b, by means of which the relative position of the upper part of the platform and the ship can be determined in one direction following a relative movement of these.
  • the hydraulic fluid can flow from the accumulator to the lifting cylinder, but reverse flow in the opposite direction is blocked. In other words, the position of the platform top with respect to the ship is frozen. This is preferably carried out during an upward movement of the ship in the lowest position of the ship.
  • the lifting cylinder forces are increased until the pull cylinders 33 are loaded in the pulling direction and remain constantly under tension even when the shaft is moving. This is done by supplying pressure medium into the individual lifting cylinders 4a, 4b. In principle, the determination of the dead weight and the center of gravity takes place as described above. After that, the lifting cylinder forces have to be adjusted by supplying pressure medium to ensure an optimal lifting process in the individual cylinders.
  • the lifting phase then takes place analogously to the exemplary embodiment described at the beginning.
  • the lift-off phase is the same as in the first and second exemplary embodiments third exemplary embodiment ended with the release of the explosive bolts.
  • the invention relates to a method and a device for removing an upper part from a substructure of an offshore platform.
  • the upper part is lifted off the substructure by means of lifting devices, the upper part and the substructure being connected to one another via controllable pulling devices, at least during a load transmission phase and the initiation of the lifting process.
  • the weight and / or center of gravity of the upper part are determined and, if necessary, the lifting and pulling devices are readjusted accordingly.
  • the tensile force introduced via the traction device is reduced, so that the upper part lifts off the substructure in a controlled manner by the force acting via the lifting device.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Earth Drilling (AREA)
  • Ship Loading And Unloading (AREA)

Abstract

La présente invention concerne un procédé et un dispositif servant à retirer une partie supérieure de l"infrastructure d"une plate-forme de forage en mer. Selon l"invention, la partie supérieure est soulevée à partir de son infrastructure au moyen de dispositifs de levage, la partie supérieure et l"infrastructure étant reliées par l"intermédiaire de dispositifs de traction commandables, au moins pendant une phase de transfert de charge et le début du processus de levage. Les forces s"exerçant sur le dispositif de traction commandable et sur le dispositif de levage permettent de déterminer le poids et/ou l"emplacement du centre de gravité de la partie supérieure, et éventuellement de commander par la suite les dispositifs de levage et de traction en conséquence. Après cette phase de transfert de charge, la force de traction appliquée au dispositif de traction diminue, de sorte que la partie supérieure s"élève de manière contrôlée en se séparant de l"infrastructure, grâce à la force s"exerçant sur le dispositif de levage.
PCT/DE2001/001752 2000-05-09 2001-05-09 Dispositif et procede servant a retirer des plates-formes de forage en mer WO2001086074A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU73869/01A AU7386901A (en) 2000-05-09 2001-05-09 Device and method for the removal of offshore platforms at sea
DE10191831T DE10191831D2 (de) 2000-05-09 2001-05-09 Vorrichtung und Verfahren zum Entfernen von Offshore-Plattformen auf See

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10022322.2 2000-05-09
DE10022322A DE10022322A1 (de) 2000-05-09 2000-05-09 System und Verfahren zum Entfernen und zur Montage von Offshore-Plattformen auf See

Publications (1)

Publication Number Publication Date
WO2001086074A1 true WO2001086074A1 (fr) 2001-11-15

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PCT/DE2001/001752 WO2001086074A1 (fr) 2000-05-09 2001-05-09 Dispositif et procede servant a retirer des plates-formes de forage en mer

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AU (1) AU7386901A (fr)
DE (2) DE10022322A1 (fr)
WO (1) WO2001086074A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007027690B3 (de) * 2007-06-15 2008-11-20 Martin Hibbing Ölbohrinsel-Sprengung
CN108612071B (zh) * 2018-05-11 2020-03-06 山东科技大学 一种半潜式海洋平台防倾覆装置
CN111268059A (zh) * 2020-02-28 2020-06-12 中远海运特种运输股份有限公司 一种海上平台拆除方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2995900A (en) * 1954-10-25 1961-08-15 William A Hunsucker Portable marine structure
US4669918A (en) * 1986-02-04 1987-06-02 Riles William G Offshore platform construction including preinstallation of pilings
US4729695A (en) * 1985-06-19 1988-03-08 Saipem, S.P.A. Process for the installation of the enbloc superstructure of an offshore platform, and equipment for carrying it practically
USH1815H (en) * 1997-03-24 1999-11-02 Exxon Production Research Company Method of offshore platform construction using a tension-moored barge
DE10026727A1 (de) 2000-03-17 2002-03-28 Mannesmann Rexroth Ag Trageinrichtung

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2995900A (en) * 1954-10-25 1961-08-15 William A Hunsucker Portable marine structure
US4729695A (en) * 1985-06-19 1988-03-08 Saipem, S.P.A. Process for the installation of the enbloc superstructure of an offshore platform, and equipment for carrying it practically
US4669918A (en) * 1986-02-04 1987-06-02 Riles William G Offshore platform construction including preinstallation of pilings
USH1815H (en) * 1997-03-24 1999-11-02 Exxon Production Research Company Method of offshore platform construction using a tension-moored barge
DE10026727A1 (de) 2000-03-17 2002-03-28 Mannesmann Rexroth Ag Trageinrichtung

Also Published As

Publication number Publication date
DE10022322A1 (de) 2001-11-15
DE10191831D2 (de) 2003-07-03
AU7386901A (en) 2001-11-20

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