US20140186124A1 - Riser assembly and method - Google Patents

Riser assembly and method Download PDF

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Publication number
US20140186124A1
US20140186124A1 US14/125,286 US201214125286A US2014186124A1 US 20140186124 A1 US20140186124 A1 US 20140186124A1 US 201214125286 A US201214125286 A US 201214125286A US 2014186124 A1 US2014186124 A1 US 2014186124A1
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US
United States
Prior art keywords
riser
section
vessel
bend
buoyancy
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.)
Abandoned
Application number
US14/125,286
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English (en)
Inventor
Zhimin Tan
Yanqiu Zhang
Qian Dong
Yucheng Hou
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.)
Baker Hughes Energy Technology UK Ltd
Original Assignee
Wellstream International Ltd
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 Wellstream International Ltd filed Critical Wellstream International Ltd
Priority to US14/125,286 priority Critical patent/US20140186124A1/en
Assigned to WELLSTREAM INTERNATIONAL LIMITED reassignment WELLSTREAM INTERNATIONAL LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HOU, YUCHENG, QIAN, Dong, TAN, ZHIMIN, ZHANG, YANQIU
Publication of US20140186124A1 publication Critical patent/US20140186124A1/en
Assigned to GE OIL & GAS UK LIMITED reassignment GE OIL & GAS UK LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: WELLSTREAM INTERNATIONAL LIMITED
Abandoned legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E21B17/012—Risers with buoyancy elements
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E21B17/015—Non-vertical risers, e.g. articulated or catenary-type
    • 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
    • F16L1/20—Accessories therefor, e.g. floats, weights
    • F16L1/24—Floats; Weights
    • 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
    • F16L11/00—Hoses, i.e. flexible pipes
    • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
    • F16L11/08—Hoses, i.e. flexible pipes made of rubber or flexible plastics with reinforcements embedded in the wall
    • F16L11/081—Hoses, i.e. flexible pipes made of rubber or flexible plastics with reinforcements embedded in the wall comprising one or more layers of a helically wound cord or wire
    • F16L11/083—Hoses, i.e. flexible pipes made of rubber or flexible plastics with reinforcements embedded in the wall comprising one or more layers of a helically wound cord or wire three or more layers

Definitions

  • the present invention relates to a method and apparatus for providing a riser assembly.
  • the present invention relates to a riser assembly suitable for use in the oil and gas industry, especially in deep and ultra-deep water applications, providing improved performance against problems associated with deeper water depth and excessive vessel motion.
  • Flexible pipe is utilised to transport production fluids, such as oil and/or gas and/or water, from one location to another.
  • Flexible pipe is particularly useful in connecting a sub-sea location (which may be deep underwater) to a sea level location.
  • Flexible pipe is generally formed as an assembly of a flexible pipe body and one or more end fittings.
  • the pipe body is typically formed as a combination of layered materials that form a pressure-containing conduit.
  • the pipe structure allows for deflections, to some degree, without causing bending stresses that impair the pipe's functionality over its lifetime.
  • the pipe body is generally built up as a combined structure including metallic and polymer layers.
  • Unbonded flexible pipe has been used for deep water (less than 3,300 feet (1,005.84 metres)) and ultra-deep water (greater than 3,300 feet) developments. It is the increasing demand for oil which is causing exploration to occur at greater and greater depths where environmental factors are more extreme.
  • the pipe body includes one or more tensile armour layers. The primary loading on such a layer is tension.
  • the tensile armour layer experiences high tension loads from a combination of the internal pressure end cap load and the self-supported weight of the flexible pipe.
  • the higher tension loads and higher tension load variation can cause fatigue damage and immature fatigue failure in the flexible pipe since such conditions are experienced over prolonged periods of time.
  • FIG. 2 illustrates a known riser assembly 200 suitable for transporting production fluid such as oil and/or gas and/or water from a sub-sea location 201 to a floating facility 202 .
  • production fluid such as oil and/or gas and/or water
  • the sub-sea location 201 is a sub-sea flow line 203 .
  • the flexible flow line 203 comprises a flexible pipe, wholly or in part, resting on the sea floor 204 or buried below the sea floor and used in a static application.
  • the floating facility may be provided by a platform and/or buoy or, as illustrated in FIG. 2 , a ship. Any such floating facility may be used, and as used herein the term “vessel” is used to encompass any floating facility.
  • the riser 200 is provided as a flexible riser, that is to say a flexible pipe connecting the ship to the sea floor installation.
  • the flexible pipe includes five segments of flexible pipe body 205 0 to 205 4 and four junctions between adjacent segments of pipe body.
  • a buoyancy aid 206 0 to 206 3 is attached in some way to the flexible pipe to give uplift to the pipe and reduce the tension loading along the pipe length. This configuration is sometimes known as a Stepped riser configuration.
  • the configuration of the riser may change due to vessel motion on the sea surface, and momentum built up in the riser from previous movement. This causes tension in the riser to vary.
  • a Stepped riser typically has a longer service life as a result of reduced top tension and reduced top tension variation.
  • the flexible pipe body 205 0 could be subjected to slacking loads and spike loads (i.e. excessively low tension or compression, and excessively high tension, respectively).
  • slacking loads and spike loads i.e. excessively low tension or compression, and excessively high tension, respectively.
  • the buoyancy aid 206 0 is moving in an upwards direction (by momentum from a previous movement), while at the same time a movement of the vessel pushes the riser in a downwards direction, this can result in compression forces or slacking of the flexible pipe body 205 0
  • the flexible pipe body 205 0 can then be subjected to a spike tension, which can be of a magnitude higher than the normal tension load.
  • the flexible pipe body 205 0 becoming slack to the point of diverting from its generally linear configuration and forming a protrusion with high angles of curvature (such as an omega-shaped protrusion). Such curvature may be harmful to the structure of the riser by overbending.
  • a riser assembly for transporting fluids from a location deep under water, comprising:
  • a riser assembly for transporting fluids from a location deep under water comprising:
  • Certain embodiments of the invention provide the advantage that potential shaking loads on the riser brought on by excessive vessel motion are reduced or eliminated from at least greater part of the riser assembly configuration.
  • the shaking loads may be of a magnitude higher than normal tension loads experienced by the riser.
  • Certain embodiments of the invention reduce or eliminate potential shaking loads from the entire riser assembly configuration.
  • Certain embodiments of the invention provide the advantage that tension load on the riser induced by the weight of the riser can be reduced.
  • Certain embodiments of the invention provide the advantage that a riser assembly for deep and ultra-deep water application is provided that can be installed relatively quickly and at relatively low cost compared to known configurations.
  • FIG. 1 illustrates a flexible pipe body
  • FIG. 2 illustrates a known riser assembly
  • FIG. 3 illustrates a riser assembly of the present invention.
  • FIGS. 4 is a flowchart illustrating a method, according to one embodiment of the invention.
  • FIG. 1 illustrates how pipe body 100 is formed in accordance with an embodiment of the present invention from a combination of layered materials that form a pressure-containing conduit. Although a number of particular layers are illustrated in FIG. 1 , it is to be understood that the present invention is broadly applicable to coaxial pipe body structures including two or more layers manufactured from a variety of possible materials. It is to be further noted that the layer thicknesses are shown for illustrative purposes only.
  • a pipe body includes an optional innermost carcass layer 101 .
  • the carcass provides an interlocked construction that can be used as the innermost layer to prevent, totally or partially, collapse of an internal pressure sheath 102 due to pipe decompression, external pressure, and tensile armour pressure and mechanical crushing loads. It will be appreciated that certain embodiments of the present invention are applicable to ‘smooth bore’ operations (i.e. without a carcass) as well as such ‘rough bore’ applications (with a carcass).
  • the internal pressure sheath 102 acts as a fluid retaining layer and comprises a polymer layer that ensures internal fluid integrity. It is to be understood that this layer may itself comprise a number of sub-layers. It will be appreciated that when the optional carcass layer is utilised the internal pressure sheath is often referred to by those skilled in the art as a barrier layer. In operation without such a carcass (so-called smooth bore operation) the internal pressure sheath may be referred to as a liner.
  • An optional pressure armour layer 103 is a structural layer with a lay angle close to 90° that increases the resistance of the flexible pipe to internal and external pressure and mechanical crushing loads.
  • the layer also structurally supports the internal pressure sheath, and typically consists of an interlocked construction.
  • the flexible pipe body also includes a first tensile armour layer 105 and optional second tensile armour layer 106 .
  • Each tensile armour layer is a structural layer with a lay angle typically between 10° and 55°. Each layer is used to sustain tensile loads and internal pressure. The tensile armour layers are often counter-wound in pairs.
  • the flexible pipe body shown also includes optional layers of tape 104 which help contain underlying layers and to some extent prevent abrasion between adjacent layers.
  • the flexible pipe body also typically includes optional layers of insulation 107 and an outer sheath 108 , which comprises a polymer layer used to protect the pipe against penetration of seawater and other external environments, corrosion, abrasion and mechanical damage.
  • Each flexible pipe comprises at least one portion, sometimes referred to as a segment or section of pipe body 100 together with an end fitting located at at least one end of the flexible pipe.
  • An end fitting provides a mechanical device which forms the transition between the flexible pipe body and a connector.
  • the different pipe layers as shown, for example, in FIG. 1 are terminated in the end fitting in such a way as to transfer the load between the flexible pipe and the connector.
  • riser there are different types of riser, as is well-known by those skilled in the art.
  • Embodiments of the present invention may be used with any suitable type of riser, such as vertical risers and catenary risers.
  • FIG. 3 shows a riser assembly 300 according to an embodiment of the present invention.
  • the riser assembly 300 includes a riser 302 formed of flexible pipe, and a number of buoyancy modules 304 1-7 attached to the riser at various positions.
  • the riser assembly configuration partly follows the shape of a Stepped riser configuration, with buoyancy modules 304 6-7 periodically spaced along the riser 302 to take the weight of the riser.
  • the number of, and distance between, the buoyancy modules will of course vary depending on the length and weight of the riser, and can be determined by a person skilled in the art.
  • This section of the riser assembly can be generally vertical so as to minimize weight and material cost.
  • a Wave configuration is a term known in the art and includes a sag bend (a U-shaped bend) and a hog bend (an inverted U-shaped bend).
  • the wave section is designated here to tolerate large vessel heave motion without introducing any shaking tension load.
  • Wave configurations are usually used only in shallow water applications, for allowing a vessel to have a greater distance of deviation from where a riser contacts the seabed. Wave configurations are considered uneconomical for deep water and ultra-deep water applications, because they require a greater pipe length requiring more materials, and require much larger buoyancy modules or a greater number of buoyancy modules to support the greater length and weight of flexible pipe. Also, for deep water, a Stepped configuration that is generally vertical enables a ship to deviate a fair degree from the touchdown position on the seabed, because of the long pipe length creating a large arc radius, and so a wave configuration is considered unnecessary.
  • the section of riser for attaching to the vessel is relatively short, such that the first buoyancy module from the top end of the riser assembly forms part of the wave section.
  • the section of riser at the hog bend may lie between around 5 and 500 metres from a base of the vessel, aptly between around 5 and 300 metres, and more aptly between 5 and 150 metres.
  • the distance of the hog bend from the surface, and thus the length of the section of riser for attaching to the vessel will depend on the weight and dimensions of the riser, vessel depth, etc. and can be determined by a person skilled in the art.
  • the wave section it is generally preferable for the wave section to be provided close enough to the surface to minimise the top tension loads, yet far enough from the surface that the buoyancy modules do not accidentally pop up to the surface or come into contact with the vessel.
  • the sag bend of the waved section will accommodate changes in the tension of the riser portion close to the vessel, as the sag bend would be raised, lowered, or moved laterally, in line with a corresponding movement of the vessel, while the buoyancy modules at the hog bend would generally hold the riser in a stable position relative to the surface.
  • the waved section therefore in effect creates two separate sections of the riser, one section for attaching to a vessel, and one section that is independent from movement of the vessel, which can be supported in a Stepped configuration.
  • the top end of the riser can be the part of the riser that receives the highest tension loading, due to it taking the highest weight of riser. This is sometimes referred to as the top tension.
  • the riser assembly of the present invention helps to ensure that the top tension remains below a predetermined value that would damage the riser.
  • the tension in the riser assembly may be proactively controlled by a skilled person to be suitable for a specific use by placing the appropriate buoyancy modules at the appropriate positions along the riser.
  • a skilled person can also determine the amount of buoyancy required to optimize the tension load on the sections of riser.
  • a riser assembly suitable for deep and ultra-deep water use, which is a cost effective way of managing tension loading.
  • the assembly is cost effective both in terms of onshore fabrication costs (using minimum pipe length and buoyancy modules that are relatively cost effective compared to other means), and offshore installation costs.
  • the assembly may also be used for dealing with highly sour service conditions, which requires a heavy pipe design (with higher top tension load).
  • FIG. 4 illustrates a method, according to one embodiment, which includes providing a riser having a plurality of buoyancy elements provided at predetermined intervals along the length of the riser for supporting the riser, and at least one further buoyancy element arranged to support the riser in a configuration for accommodating tension changes in the riser due to vessel movement.
  • the method can optionally include transporting fluid(s) (e.g., oil, gas, and/or water) from a location deep under water to a vessel on the water surface via the riser.
  • fluid(s) e.g., oil, gas, and/or water
  • the number of buoyancy modules used may be varied to suit the specific conditions of use.
  • the relative positions of the buoyancy modules may vary from that shown in FIG. 3 , as long as the general principle of accommodating tension changes in the riser due to vessel movement is achieved.
  • the wave configuration may be provided relatively closer to the vessel, or closer to the sea bed, depending on the riser dimensions, weight, type of water body that the riser assembly will be used in, etc.
  • the buoyancy modules may be attached by any known means to the riser, such as attachment to a rigid buoyancy support between sections of flexible pipe.
  • the buoyancy modules may be any suitable structure for providing buoyancy to the riser, such as metal cans filled with air for example, or other such structure.
  • buoyancy modules rather than using a plurality of buoyancy modules to create the sag bend near the vessel, a single, larger buoyancy module could be employed. However, in general, smaller buoyancy modules are more cost effective to use.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Physics & Mathematics (AREA)
  • Earth Drilling (AREA)
  • Steroid Compounds (AREA)
  • Lubricants (AREA)
US14/125,286 2011-06-16 2012-05-08 Riser assembly and method Abandoned US20140186124A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14/125,286 US20140186124A1 (en) 2011-06-16 2012-05-08 Riser assembly and method

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US201161497885P 2011-06-16 2011-06-16
US14/125,286 US20140186124A1 (en) 2011-06-16 2012-05-08 Riser assembly and method
PCT/GB2012/050942 WO2012172305A2 (fr) 2011-06-16 2012-05-08 Ensemble colonne montante et procédé associé

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US20140186124A1 true US20140186124A1 (en) 2014-07-03

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US14/125,286 Abandoned US20140186124A1 (en) 2011-06-16 2012-05-08 Riser assembly and method

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US (1) US20140186124A1 (fr)
EP (1) EP2721244A2 (fr)
CN (1) CN103781987A (fr)
AU (1) AU2012270172A1 (fr)
BR (1) BR112013031949A2 (fr)
WO (1) WO2012172305A2 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201212701D0 (en) * 2012-07-17 2012-08-29 Silixa Ltd Structure monitoring
US9708864B2 (en) * 2014-12-22 2017-07-18 Ge Oil & Gas Uk Limited Riser assembly and method of forming a riser assembly
AU2016305123A1 (en) * 2015-08-10 2018-03-08 National Oilwell Varco Denmark I/S An unbonded flexible pipe
US20190195025A1 (en) 2017-12-22 2019-06-27 Ge Oil & Gas Uk Limited Apparatus and method
GB2577107B (en) 2018-09-14 2021-06-16 Subsea 7 Do Brasil Servicos Ltda Installation of subsea risers

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4906137A (en) * 1988-02-24 1990-03-06 Coflexip Apparatus for transferring fluid between subsea floor and the surface
WO2010052422A2 (fr) * 2008-11-05 2010-05-14 Technip France Procédé de montage d'une tour d'exploitation d'un fluide dans une étendue d'eau et tour d'exploitation associée
US20110146797A1 (en) * 2007-11-16 2011-06-23 Wellstream International Limited Flexible pipe support

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0227850D0 (en) * 2002-11-29 2003-01-08 Stolt Offshore Sa Subsea structure and methods of construction and installation thereof
GB0608327D0 (en) 2006-04-27 2006-06-07 Wellstream Int Ltd Riser assembly
FR2929638B1 (fr) * 2008-04-08 2010-05-14 Technip France Dispositif d'extraction d'un materiau situe au fond d'une etendue d'eau, installation d'extraction, et procede associe
WO2010036792A2 (fr) * 2008-09-24 2010-04-01 Schlumberger Technology Corporation Procédé, dispositif, et système pour évaluer l'eau ou le liquide dans l'espace annulaire d'une colonne montante ou d'une conduite flexibles
GB0818500D0 (en) * 2008-10-09 2008-11-19 Wellstream Int Ltd Flexible pipe
GB0920640D0 (en) * 2009-11-25 2010-01-13 Subsea 7 Ltd Riser configuration

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4906137A (en) * 1988-02-24 1990-03-06 Coflexip Apparatus for transferring fluid between subsea floor and the surface
US20110146797A1 (en) * 2007-11-16 2011-06-23 Wellstream International Limited Flexible pipe support
WO2010052422A2 (fr) * 2008-11-05 2010-05-14 Technip France Procédé de montage d'une tour d'exploitation d'un fluide dans une étendue d'eau et tour d'exploitation associée

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Publication number Publication date
CN103781987A (zh) 2014-05-07
BR112013031949A2 (pt) 2016-12-20
EP2721244A2 (fr) 2014-04-23
AU2012270172A1 (en) 2013-12-19
WO2012172305A2 (fr) 2012-12-20
WO2012172305A3 (fr) 2013-04-18

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AS Assignment

Owner name: WELLSTREAM INTERNATIONAL LIMITED, UNITED KINGDOM

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TAN, ZHIMIN;ZHANG, YANQIU;QIAN, DONG;AND OTHERS;REEL/FRAME:032043/0581

Effective date: 20110720

AS Assignment

Owner name: GE OIL & GAS UK LIMITED, UNITED KINGDOM

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:WELLSTREAM INTERNATIONAL LIMITED;REEL/FRAME:034013/0657

Effective date: 20141017

STCB Information on status: application discontinuation

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