EP2886786A1 - Stahlproduktionssteigleitung, Offshore-Kohlenwasserstoffherstellungssystem und Verfahren zur Erzeugung eines Kohlenwasserstoffstroms - Google Patents

Stahlproduktionssteigleitung, Offshore-Kohlenwasserstoffherstellungssystem und Verfahren zur Erzeugung eines Kohlenwasserstoffstroms Download PDF

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Publication number
EP2886786A1
EP2886786A1 EP13198736.4A EP13198736A EP2886786A1 EP 2886786 A1 EP2886786 A1 EP 2886786A1 EP 13198736 A EP13198736 A EP 13198736A EP 2886786 A1 EP2886786 A1 EP 2886786A1
Authority
EP
European Patent Office
Prior art keywords
section
buoyancy
riser
point
production riser
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Withdrawn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
EP13198736.4A
Other languages
English (en)
French (fr)
Inventor
Kok-Chieng LIM
Jan Willem Van De Graaf
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.)
Shell Internationale Research Maatschappij BV
Original Assignee
Shell Internationale Research Maatschappij BV
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 Shell Internationale Research Maatschappij BV filed Critical Shell Internationale Research Maatschappij BV
Priority to EP13198736.4A priority Critical patent/EP2886786A1/de
Priority to AU2014368814A priority patent/AU2014368814B2/en
Priority to PCT/EP2014/078171 priority patent/WO2015091616A2/en
Priority to AP2016009250A priority patent/AP2016009250A0/en
Priority to BR112016014076-1A priority patent/BR112016014076B1/pt
Publication of EP2886786A1 publication Critical patent/EP2886786A1/de
Withdrawn legal-status Critical Current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
    • E21B17/015—Non-vertical risers, e.g. articulated or catenary-type
    • 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

Definitions

  • the present invention relates to a steel production riser.
  • the present invention relates to an offshore hydrocarbon production system provided with such a steel production riser.
  • the present invention relates to a method of producing a hydrocarbon stream.
  • a steel production is a steel riser, typically formed out of a string of pipes made out of steel, arranged to convey mineral hydrocarbon fluids produced from a subsea hydrocarbon reservoir to a floating structure such as a floating production platform, a floating production storage and offloading (FPSO) structure, a semi-submersible.
  • a floating structure such as a floating production platform, a floating production storage and offloading (FPSO) structure, a semi-submersible.
  • FPSO floating production storage and offloading
  • the primary buoyancy section lifts up parts of the riser adjacent to the primary buoyancy section, whereby a downwardly convex section (so-called sag bend) can form hanging between the floating structure and the primary buoyancy section.
  • a downwardly convex section (so-called sag bend) can form hanging between the floating structure and the primary buoyancy section.
  • This causes a waved or shaped path.
  • the presence of both a hog and a sag bend distinguish a lazy wave riser from a steel catenary riser or a shaped steel catenary riser.
  • the shaped steel catenary riser can be seen as a transitional form between the catenary and the lazy wave riser: it also has a buoyancy section, similar to the primary buoyancy section and which also changes the trajectory of the riser in the body of water, but the amount of buoyancy is not enough to raise the buoyancy section high enough to form actual hog and arch bends.
  • a steel production riser, steel production riser comprising a string of pipes made out of steel, which string of pipes is suspended from a floating structure into a body of water above a seabed, on which body of water the structure floats, wherein at a hang-off end of the riser the string of pipes is connected to the floating structure in a hang-off point, and extending to the seabed wherein, as seen along the string of pipes starting from the hang-off point, distal to a touchdown point which corresponds to a first point of contact of the production riser with the sea bed the production riser comprises a touchdown section wherein the pipes rest on the seabed, whereby the string of pipes in the touchdown point are tangentially aligned with the seabed, further comprising an auxiliary buoyancy section extending from a point between the hang-off point and the touchdown point into the touchdown section, whereby the touchdown point is located within the auxiliary buoyancy section, in which auxiliary buoyancy section the production riser is provided with
  • an offshore hydrocarbon production system comprising a floating structure floating on a body of water above a seabed, and a steel production riser according to any aspect of the present invention suspended from said floating structure into said body of water.
  • a method of producing a hydrocarbon stream comprising conveying mineral hydrocarbon fluids produced from a subsea hydrocarbon reservoir to a floating structure via a steel production riser in accordance with the first aspect of the invention, and processing the mineral hydrocarbon fluids on the floating structure whereby forming the hydrocarbon stream out of the mineral hydrocarbon fluids.
  • a production riser which comprises an auxiliary buoyancy section around the touchdown point, in which auxiliary buoyancy section the riser is provided with a first set of external buoyancy modules as a result of which the upward buoyancy force on the auxiliary buoyancy section in the body of water is smaller than the downward gravity force.
  • the touchdown point is located in the auxiliary buoyancy section.
  • the auxiliary buoyancy section helps to reduce the curvature in the touchdown zone compared to the same riser having no auxiliary buoyancy section around the touchdown point. Fatiguing of the riser pipes around the touchdown point transition can be reduced by reducing the downwardly convex curvature in this area.
  • the sets of external buoyancy modules each comprise a plurality of external buoyancy modules.
  • the external buoyancy modules in any of the first, and second set may be embodied in distributed buoyancy configuration, whereby distinct external buoyancy modules are attached to the riser with a selected spacing between successive adjacent external buoyancy modules. This includes a so-called full coverage configuration, whereby the spacing is zero or close to zero and the successive adjacent external buoyancy modules are configured in a physically abutting configuration.
  • gravity force in any named section of the steel production riser refers to the downward force exerted by gravity on the mass of the production riser in the section, normalized to a unit of length, including contents of the production riser and any external buoyancy modules.
  • Contents include the fluids that are being conveyed through the production riser, typically from the seabed to the floating structure.
  • these fluids comprise mineral hydrocarbon fluids produced from a subsea hydrocarbon reservoir.
  • upward buoyancy force in any named section of the waved steel production riser refers to the upward force imposed on the production riser in the section by the weight of water from the body of water that is displaced by that section of the production riser (including the riser pipes and the external buoyancy modules), normalized to the same unit of length.
  • the upward buoyancy force on the primary buoyancy section is generally higher than the upward buoyancy force on the auxiliary buoyancy section.
  • This can be achieved for instance by selecting external buoyancy modules in the second set that per external buoyancy module have more buoyancy than the external buoyancy modules per module in the first set (per module). This may be achieved by selecting external buoyancy modules with lower density and/or larger volume for use in the second set compared to those for use in the first set.
  • the spacing between successive adjacent external buoyancy modules in the primary buoyancy section may be selected smaller than the spacing between successive adjacent external buoyancy modules in the auxiliary buoyancy section. In this case, the external buoyancy modules in the second set can be exact copies of those used in the first set.
  • the steel production riser according to the present invention can be used on any type offshore hydrocarbon production system on any type of floating structure.
  • floating structure include a floating production platform, a floating production storage and offloading (FPSO) structure, a semi-submersible structure, and a SPAR.
  • a tension leg platform (TLP) may also be considered a floating structure on which the steel production riser of the invention can be beneficial.
  • a floating liquefied natural gas (FLNG) barge is a special example of FPSO, and it contains process equipment and utilities by which natural gas can be produced from a subsea reservoir, treated, and finally cooled down to produce liquefied natural gas (LNG) at a pressure of less than 2 bar absolute.
  • Fig. 1 shows an offshore hydrocarbon production system including a steel production riser 100 embodied in the preferred form of a steel catenary riser.
  • the system comprises a floating structure 10, which floats on the surface 25 of a body of water 20, above a seabed 30.
  • the steel production riser 100 is suspended from the floating structure 10, into the body of water 20.
  • the steel production riser 100 is generally constructed in the form of a string of pipes made out of steel.
  • the string of pipes is connected to the floating structure 10 in a hang-off point 110.
  • the steel production riser 100 extends all the way to the seabed 30.
  • a touchdown point which corresponds to a first point of contact of the production riser 100 with the seabed 30 as seen from the hang-off point, the production riser 100 comprises a touchdown section 105 wherein the pipes rest on the seabed 30.
  • the string of pipes in the touchdown point are tangentially aligned with the seabed 30. In the context of the present disclosure, this tangent alignment characterizes the term "lazy" in the configuration of the riser.
  • the first point of contact 115 is dynamic as motion of the floating structure 10 causes the riser to be lifted off from or laid down on the seabed 30. Fatiguing of the riser pipes around the transition between the touchdown section 105 and the riser sections proximal to the floating structure relative to the first point of contact 115 can be reduced by reducing the downwardly convex curvature in this area.
  • the steel production riser 100 comprises an auxiliary buoyancy section 106, which extends from within the touchdown section 105 a point between the hang-off point 110 and the touchdown point in the first point of contact 115. Thus, the touchdown point is located within the auxiliary buoyancy section 106.
  • the production riser 100 is provided with a first set of external buoyancy modules 140, whereby the upward buoyancy force on the auxiliary buoyancy section 106 within the body of water is smaller than the downward gravity force. Moreover, the upward buoyancy force in the body of water within the auxiliary buoyancy section 106 is higher than the upward buoyancy force in the body of water of the string of pipes made out of steel without any external buoyancy modules. The net force, however, remains downwardly directed (sinking).
  • the upward buoyancy force in the body of water within the auxiliary buoyancy section 106 of the production riser 100 is preferably selected between 40% and 99% of the downward gravity force in the same section. At 99% the riser section is considered neutrally buoyant for practical purposes. More preferably the upward buoyancy force in the body of water within the auxiliary buoyancy section 106 of the production riser 100 is selected between 40% and 90% of the downward gravity force in the same section. The range of between 40% and 90% is preferred over the range between 90% and 99% in order to keep some more strain on the riser and less transverse movement of the riser over the sea bed.
  • the upward buoyancy force in the body of water within the auxiliary buoyancy section 106 of the production riser 100 is selected between 50% and 90% of the downward gravity force in the same section, and most preferably between 60% and 90% of the downward gravity force in the same section.
  • This is generally achieved by purposely selecting the spacing between the external buoyancy modules in the first set and/or their sizes.
  • the spacing between the external buoyancy modules in the first set and/or their sizes are sized such that the pipe weight is reduced to between 10% and 40% of the bare pipe weight including its contents.
  • the external buoyancy modules are provided in distributed buoyancy configuration.
  • Each of the modules may consist of parts (usually two halves provided with an internal recess) and a clamping system that can be clamped around the pipes in the riser.
  • the parts suitably comprise a syntactic foam.
  • Suitable external buoyancy modules are available from a variety of vendors.
  • buoyancy modules may be applied pendant to the riser pipes whereby the external buoyancy modules are anchored to the riser pipes by anchor lines. These external buoyancy modules would still be configured fully submerged to benefit from maximal buoyancy force. This alternative may be preferred if contact of the external buoyancy modules in the auxiliary buoyancy section would cause unacceptable abrasion as a result of physical contact with the seabed 30. Such physical contact would be avoided using the pendant buoys.
  • the steel production riser 100 is a steel lazy wave riser.
  • the steel production riser 100 is a shaped catenary riser. In both cases, as seen from the floating structure 10, and as described along the string of pipes starting from the hang-off point 110, the production riser 100comprises:
  • the touchdown section 105 is distal from a touchdown point which coincides with the first point of contact 115.
  • the steel lazy wave riser 100 is curved with a downwardly convex curvature.
  • the totality of the external buoyancy modules 130 in the second set cause an upward buoyancy force on the primary buoyancy section 103 within the body of water 20, that is greater than a downward gravity force in the primary buoyancy section 103. Therefore, within the primary buoyancy section 103 the steel lazy wave riser 100 floats.
  • the primary buoyancy section 103 generally does not reach the surface 25 of the body of water as it is pulled down by the hanging section 102 and the landing section 104.
  • the auxiliary buoyancy section extends from a point within the landing section 104 (between the primary buoyancy section 103 and the first point of contact 115) and into the touchdown section 105.
  • the hanging section 102 hangs between the floating structure 10 and the primary buoyancy section 103.
  • a downwardly convex curved section is formed in the hanging section 103.
  • a sag point 125 is defined in the lowest point on the downwardly convex curved section, there where the riser has a tangent 127 in a horizontal direction and parallel to an imaginary vertical plane, which spans between the hang-off point 110 and the first point of contact 115.
  • the buoyancy force in the primary buoyancy section 103 is not high enough to actually form the arch bend.
  • the fact that the upward buoyancy force in the auxiliary buoyancy section 106 is kept smaller than the downward gravity force is a distinct difference of the auxiliary buoyancy section 106 compared to the primary buoyancy section 103.
  • the external buoyancy modules in the first and second sets may be of the same types as those discussed above with reference to Fig. 1 .
  • the external buoyancy modules in the second set may be of the same type as those used in the first set.
  • generally the clamped distributed configuration may be preferred for the primary buoyancy section 103.
  • the invention is applicable on steel production risers having pipes of any outer diameter, including steel production risers having pipes of which the outer diameter exceeds 199 mm (which includes 8-inch pipes). Notwithstanding, fatigue phenomena in the touchdown area are generally more of concern for larger diameters. Hence the invention has more benefit on steel production risers of which the outer diameter exceeds 249 mm (which includes 10-inch pipes), and even more when the outer diameter exceeds 299 mm (which includes 12-inch pipes, and up).
  • the water depth exceeds 500 m. It is envisaged that below this depth the choice of steel for the risers would generally be outcompeted by alternatives, such as flexible risers.
  • the steel production riser described herein can be used in a variety of methods of producing a hydrocarbon stream.
  • mineral hydrocarbon fluids may be produced from a subsea hydrocarbon reservoir to the floating structure via the steel production riser. Subsequently, on the floating structure, the mineral hydrocarbon fluids are processed whereby the hydrocarbon stream is formed out of the mineral hydrocarbon fluids.
  • Processing may include any kind of known hydrocarbon processing steps, including separation steps to remove undesired components from the hydrocarbon fluids such as water, acids, hydrate inhibitors, sulphur components, mercury. Processing may further include (field) stabilization of hydrocarbon liquids, and purification of hydrocarbon gases.
  • the produced hydrocarbon stream may be stored and off-loaded in batches (bulk transportation).
  • process steps may be applied by which the natural gas is treated, and finally cooled down to produce the hydrocarbon stream in the form of liquefied natural gas (LNG).
  • LNG liquefied natural gas
  • Such LNG is typically also stored in (or on) the floating structure, and off-loaded in batches like described for FPSO and SPAR.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
EP13198736.4A 2013-12-20 2013-12-20 Stahlproduktionssteigleitung, Offshore-Kohlenwasserstoffherstellungssystem und Verfahren zur Erzeugung eines Kohlenwasserstoffstroms Withdrawn EP2886786A1 (de)

Priority Applications (5)

Application Number Priority Date Filing Date Title
EP13198736.4A EP2886786A1 (de) 2013-12-20 2013-12-20 Stahlproduktionssteigleitung, Offshore-Kohlenwasserstoffherstellungssystem und Verfahren zur Erzeugung eines Kohlenwasserstoffstroms
AU2014368814A AU2014368814B2 (en) 2013-12-20 2014-12-17 Steel production riser, offshore hydrocarbon production system, and method of producing a hydrocarbon stream
PCT/EP2014/078171 WO2015091616A2 (en) 2013-12-20 2014-12-17 Steel production riser, offshore hydrocarbon production system, and method of producing a hydrocarbon stream
AP2016009250A AP2016009250A0 (en) 2013-12-20 2014-12-17 Steel production riser, offshore hydrocarbon production system, and method of producing a hydrocarbon stream
BR112016014076-1A BR112016014076B1 (pt) 2013-12-20 2014-12-17 Tubo ascendente de produção de aço, sistema de produção de hidrocarboneto fora da costa, e, método para produzir uma corrente de hidrocarboneto

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP13198736.4A EP2886786A1 (de) 2013-12-20 2013-12-20 Stahlproduktionssteigleitung, Offshore-Kohlenwasserstoffherstellungssystem und Verfahren zur Erzeugung eines Kohlenwasserstoffstroms

Publications (1)

Publication Number Publication Date
EP2886786A1 true EP2886786A1 (de) 2015-06-24

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Application Number Title Priority Date Filing Date
EP13198736.4A Withdrawn EP2886786A1 (de) 2013-12-20 2013-12-20 Stahlproduktionssteigleitung, Offshore-Kohlenwasserstoffherstellungssystem und Verfahren zur Erzeugung eines Kohlenwasserstoffstroms

Country Status (5)

Country Link
EP (1) EP2886786A1 (de)
AP (1) AP2016009250A0 (de)
AU (1) AU2014368814B2 (de)
BR (1) BR112016014076B1 (de)
WO (1) WO2015091616A2 (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006073887A2 (en) * 2005-01-03 2006-07-13 Seahorse Equipment Corporation Dynamic motion suppression of riser, umbilical and jumper lines
US20120263542A1 (en) * 2009-12-04 2012-10-18 Geir Olav Hovde Assembly for connecting a flexible tubular line to an underwater installation
WO2013167710A2 (en) * 2012-05-08 2013-11-14 Wellstream International Limited Riser assembly and method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006073887A2 (en) * 2005-01-03 2006-07-13 Seahorse Equipment Corporation Dynamic motion suppression of riser, umbilical and jumper lines
US20120263542A1 (en) * 2009-12-04 2012-10-18 Geir Olav Hovde Assembly for connecting a flexible tubular line to an underwater installation
WO2013167710A2 (en) * 2012-05-08 2013-11-14 Wellstream International Limited Riser assembly and method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SHANKAR BHAT ET AL: "Pragmatic Solutions to Touch-Down Zone Fatigue Challenges in Steel Catenary Risers", OFFSHORE TECHNOLOGY CONFERENCE, 3 May 2004 (2004-05-03), pages 3 - 6, XP055114602, DOI: 10.4043/16627-MS *

Also Published As

Publication number Publication date
AU2014368814A1 (en) 2016-06-16
WO2015091616A3 (en) 2015-10-01
AP2016009250A0 (en) 2016-06-30
BR112016014076B1 (pt) 2021-11-30
WO2015091616A2 (en) 2015-06-25
AU2014368814B2 (en) 2017-03-02
BR112016014076A2 (pt) 2017-08-08

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