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
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/02—Surface sealing or packing
  • E21B33/03—Well heads; Setting-up thereof
  • E21B33/035—Well heads; Setting-up thereof specially adapted for underwater installations
  • E21B33/038—Connectors used on well heads, e.g. for connecting blow-out preventer and riser
• • 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
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/02—Surface sealing or packing
  • E21B33/03—Well heads; Setting-up thereof
  • E21B33/068—Well heads; Setting-up thereof having provision for introducing objects or fluids into, or removing objects from, wells
  • E21B33/076—Well heads; Setting-up thereof having provision for introducing objects or fluids into, or removing objects from, wells specially adapted for underwater installations

Definitions

• the present invention regards a method for performing intervention in a well, and a device for performing intervention in a well.
• crown plugs When performing intervention work on subsea wells with horizontal Christmas trees it is necessary to remove the so-called crown plugs to gain access to the well bore.
• These crown plugs have the same outer diameter as the production tubing, normally 5 inches nominal outer diameter (OD).
• OD nominal outer diameter
• the operations for performing the actual work during the intervention will not normally require such large bore since the tools used normally are of smaller outer diameter.
• the size of the riser used will have to conform to the larger crown plugs instead of the smaller tools and that adds weight to the riser in proportion to its cross section.
• a large bore riser accommodating the pulling of a crown plug may for instance be twice as heavy as a riser needed for performing coiled tubing operations as such.
• a riser connector for connecting a riser to a wellhead assembly having a bore there through.
• the connector includes a housing having a first and second end.
• the first end of the housing has an opening and is adapted for mounting to the wellhead assembly with the opening in communication with the bore of the wellhead assembly.
• the second end has a first opening connectable to the riser having a diameter at least the same as the inner diameter of the riser, and a second opening, having a diameter at least substantially the same as the diameter of the bore of the wellhead assembly.
• first well operations are conducted through the riser in the conventional manner.
• Second well operations are conducted using open water techniques and access the wellhead assembly and the well through the second conduits in the connector without the need to disconnect the riser from the connector.
• An aim with the present invention is to provide a method and device for performing intervention work in a well. This is achieved with the method and device according to the attached claims.
• a method for performing intervention in a subsea well comprises the steps of connecting a riser element to a wellhead and providing a connector element comprising a first end with a first opening connected to the wellhead and a second end with a at least two openings, a second opening and a third opening, fluid paths through the connector connecting the first opening with both the at least second and third opening, and means for closing and opening the fluid paths through second and third opening and where the second opening is connected to the riser element
• the riser element may be a riser extending to a floating vessel on the surface or possibly only extending for a distance from the wellhead.
• the riser element may be and is preferably formed to withstand pressure and hydrocarbons.
• the riser element is thereby equipped to withstand the well fluid in a live well.
• the second opening, and thereby also the riser element will normally have an inner diameter which is smaller than the fluid path in the wellhead.
• the third opening will normally have an inner diameter substantially equal to or larger than an inner diameter of the fluid path in the wellhead. This gives two different possible entries to the well, having different inner diameter, and one may thereby use the different entries for different equipment needing different diameters.
• the method comprises the steps of providing a displacement fluid within the connector element, closing the second opening, attaching well operation equipment to the third opening, performing operation in the well through the third opening, thereafter closing the well at a position below the connector element, opening the second opening towards the riser element and again providing a displacement fluid within the connector element and then removing the well operation equipment attached to the third opening.
• the step of providing a displacement fluid within the connector element will in the case when the intervention work is starting involve adding a displacement fluid to the connector element and thereby displace seawater or another fluid inside the connector element.
• One possible solution to this is to provide valve means at the first opening of the connector element.
• Another possibility is to use already existing valves in the well below the connector element. Such valves may for instance be a valve in the X-mas tree or further down in the well.
• a riser element should in this application be understood to be a riser element not necessary extending all the way to the surface of the water, but possibly a riser element extending all the way to the surface of the water and to a floating vessel.
• the riser element may be a shorter riser element, forming a tank for the fluid displaced out of the connector element, when the displacement fluid is added to the connector element.
• the riser element may extend to another subsea facility.
• a second and a third opening for instance a fourth and fifth opening at the second end of the connector element.
• additional openings will normally be in a closed state as they normally will lead out to the surroundings of the wellhead.
• the fluid path through these openings may be closed by valve means or plugs in the openings or in a different position in the fluid path or possibly by the tool equipment attached to the opening, since the tool equipment in it self is closed to the surroundings.
• the method may comprise the step of providing a displacement fluid within the connector element which displacement fluid is heavier than a well fluid in the riser, and where this displacement fluid is added at a position above the connector element.
• a displacement fluid within the connector element which displacement fluid is heavier than a well fluid in the riser, and where this displacement fluid is added at a position above the connector element.
• One possibility is to add the displacement fluid in the riser element above the connector element. The displacement fluid will then due to gravity replace any well fluid in the connector element. This replacement will be helped if the second opening is open and the fluid in the connector element is allowed to evacuate into the riser element. At the same time the displacement fluid may be moved from the riser element to the connector element.
• the method may comprise pulling a unit with an outer diameter larger than an inner diameter of the riser element from the well, out through the third opening.
• This unit may for instance be a crown plug in a horizontal X-mas tree.
• the second opening may have an inner diameter smaller than the inner diameter of the third opening, and also the inner diameter of the fluid path in the wellhead.
• the displacement fluid may be a hydrate inhibiting fluid such as MonoEthylen Glycol (MEG).
• MEG MonoEthylen Glycol
• Ethylen Glycol or Glycol environmentally friendly
• TriEthylenGlycol or alternatively Brine (Saltwater) as a displacement fluid.
• the method may comprise connecting a tool equipment in relation to the third opening before the third opening is opened for access to the well.
• the connection of the tool equipment may open the third opening or there may be separate means for opening and closing the fluid path through the third opening.
• the tool equipment may also comprise means for opening the third opening after the tool equipment is attached to the connector element.
• the tool equipment for connection to the third opening may be a pressure control head (PCH) or a wire line operated winch equipment (WL Winch) or a remotely operated tool equipment.
• the attachment of the tool equipment to the third opening may be assisted by the use of a ROV.
• the method may comprise providing a riser element comprising a connector element from an upper end of a horizontal X- mas tree and to a floating unit.
• the connector element may be provided between the emergency disconnect pack (EDP) and the riser element, between the emergency disconnect pack (EDP) and a stress joint connected to the riser element, between the stress joint and the riser element or the connector element may form a stress joint in the riser.
• well operation through the second opening in the connector element may be performed through a moon pool in a floating vessel. These operations may then be performed through a riser extending from the connector element and up to the vessel. Alternatively there may be a wire line operation performed through the moon pool.
• Operations through the third opening of the connector element may be performed outside the hull of the vessel. This may for instance be in the aft of the vessel. Another possibility is to have several moon pools and performing the operations in the second and third opening in separate moon pools. In the case with a fourth opening the operations in the third opening may be formed on one side of the vessel and the operations in the fourth opening on the other side of the vessel.
• the invention also relates to a connector element for use in well operations.
• the connector element comprises a first end with a first opening and a second end with at least a second opening and a third opening, fluid paths through the connector connecting the first opening with both the at least second and third openings, and means for closing and opening the fluid paths through the at least second and third openings.
• the connector element further comprises a fluid connection between a position close to the third opening and the fluid path between the first opening and the second opening.
• the second end may comprise more than two openings, as a second, third and fourth opening or a second, third, fourth and fifth opening. This will give several access points to the well. In such cases there will be a fluid connection between these additional openings and the fluid path between the first opening and the second opening.
• the fluid connection may comprise means for closing and opening the fluid connection.
• the means for closing and opening the fluid path through the second opening may comprise a valve device positioned in the fluid path.
• the means for closing and opening the fluid path may be a common valve device or there may be valve devices in equipment attached to the connector element which closes or opens for the fluid path, alternatively there may be plug means operated from the surface through the rise element.
• the fluid connection may be connected to the fluid path between the first and second opening in a position closer to the second opening than a valve device in that fluid path. In normal use this will give that the fluid connection will be attached to the fluid path between the first opening and the second opening in a position above a valve device within this fluid path.
• the fluid connection will normally have an internal diameter smaller than the diameters of the openings in the second end of the connector element. By having a smaller fluid connection with a valve device in this fluid connection one may by opening the fluid connection valve bleed pressure from one side of the valve in the fluid path between the first and second opening to the other side, and then more easily open a valve in this fluid path. Alternatively the connection point of the fluid connection will be below the valve device in this fluid path. In this last instance the fluid connection may be formed without a valve device in the fluid connection.
• the first end of the connector element may be adapted to be connected to the wellhead.
• the second opening of the second end may be adapted to be connected to a riser element and the third opening of the second end may be adapted to be connected to a tool element.
• the second opening may have a smaller internal diameter than an internal diameter of the third opening.
• DHSF down hole safety valve
• Some of the tools attached to the connector element may be relative short and thick and possibly with a relative large diameter needing a large diameter opening, for instance for pulling the plugs, while other tools for performing work down in the well may be relatively long and thin and with a smaller diameter opening, for instance wire line tools for operation in the well.
• Fig. 1 is a schematic figure showing a first embodiment of the invention
• Fig. 2 is a schematic figure showing a second embodiment
• Fig. 3 is a sketch of a third embodiment of the connector element
• Fig. 4 is a sketch of a fourth embodiment of the connector element
• Fig. 5 is a sketch of a fifth embodiment of the connector element
• Fig. 6 is a sketch of a sixth embodiment of the connector element
• Fig. 7a-7f show the different steps in a method according to the invention.
• the present invention regard a method and device for performing intervention work in a well 1 normally for exploitation of hydrocarbons, as shown in fig. 1.
• a wellhead 2 attached to the well 1.
• This wellhead 2 may comprise a horizontal X-mas tree with a horizontal production outlet from the wellhead (not shown).
• To perform intervention work in the well it is normal to gain access to the well from the top of the wellhead 2. According to the invention this may be achieved by providing a riser element 8 extending the fluid path in the wellhead from the wellhead 2 and up to a floating vessel 9.
• a connector element 10 between the riser element 8 and the wellhead 2.
• This connector element 10 comprises a first end 11 with one opening 110, and this first end 11 is attached to the wellhead 2 during use.
• the connector element 10 has a second end 12, this second end 12 comprises several openings, a second opening 120 and a third openingl 30.
• the second opening 120 is connected to the riser element 8 and this provides a continuing fluid path from the wellhead 2 through the connector element 10 and the riser element 8 through to the vessel 9.
• the second opening 120 and the third opening 130 are positioned such that the connector element forms a Y- shape. Depending on the use of the two openings on the second end the orientation of these may be varied.
• a fluid connection 13 between the third opening and the fluid path between the second opening 120 and first opening 1 10.
• This fluid connection 13 is favorably of a smaller diameter than the diameter of the openings.
• the fluid connection 13 is also favorably either extending in a mainly horizontal direction or in an upwards direction from the connection point to the third opening. Coiled tubing operations in this configuration may be performed through the riser element 8 which has a diameter smaller than the opening of the fluid path in the wellhead 2, while a plug in the fluid path in the wellhead 2 may be pulled through the third opening 130 having a diameter similar to the fluid path in the wellhead. The operations through the third opening 130 may be performed over the side of the vessel.
• connector element may have more than two openings 120,130 at the second end, with a fourth opening 140.
• One may perform wire line operations through a moon pool in the vessel and through the opening 140 and wire line operations from the side of the vessel through the third opening 130.
• There may also be a shorter riser element 8 attached to the second opening 120.
• FIG. 3 there is shown a third embodiment where the connector element 10 is attached to an emergency quick disconnect joint 7, which is connected to a wellhead (not shown).
• a stress joint 6 which again is connected to a riser element (not shown).
• a first valve means 14 is positioned in the first opening 1 10, and a second valve means 15 is positioned in the second opening 120.
• the second valve means 15 is also positioned relatively above the connection point of the fluid connection 13 to the fluid path between the first opening 1 10 and the second opening 120.
• the first opening 110 has a diameter 18 which is larger than a diameter 19 of the second opening 120, while similar to a diameter 20 of the third opening 130.
• a winch package tool 25 to the third opening 130.
• This tool 25 may be used to pull a plug within for instance the wellhead.
• the winch package tool 25 may be autonomous, and/or remotely operated or operated with lines from the vessel.
• a plug 16 as closing means for the third opening 130.
• a Pressure Control Head (PCH) 24 may be attached to the third opening 130.
• This PCH 24 may comprise equipment for pulling the plug 16 and performing work in the well and thereafter setting the plug 16 again.
• the connector element 10 is in itself a stress joint 6, and positioned between a riser element 8 and an emergency disconnect joint 7, attached to the wellhead (not shown)
• the connector element is attached between a stress joint 6 attached to an emergency disconnect joint 7, attached to the wellhead (not shown) and a riser element 8.
• the fluid connection 13 between the third opening 130 and the fluid path between the first opening 1 10 and the second opening 120 is connected to this fluid path in a position above the valve means 15 in this fluid path.
• connection valve means 17 which may open or close the fluid connection 13.
• the fluid connection 13 is connected to the fluid path between the first opening 1 10 and the third opening 130 close to and or at the third opening 130.
• fig. 7a to 7f there is shown a sequence of operations according to the invention.
• a riser element 8 to a wellhead 2 with a connector element 10 between them.
• a displacement fluid within the connector element 10 by adding it in the riser element 8. This displacement fluid is prevented from entering the well by the crown plug 4, working as a well valve in this case since the crown plug 4 is still not pulled.
• a tool equipment is attached to the third opening 130 which is opened positioning a retrieving tool 23 just below the third opening 130.
• the retrieving tool 23 is by operating the wire line 26 lowered to the crown plug 4 to retrieve the crown plug.
• the second valve means 15 for the second opening 120 is moved to a closed state and connection valve means 17 within the fluid connection 13 is moved to a closed state.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)

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Cited By (1)

Citations (6)

• 2008
  • 2008-10-31 NO NO20084617A patent/NO332212B1/no unknown
• 2009
  • 2009-10-29 WO PCT/NO2009/000378 patent/WO2010050827A1/en active Application Filing

Patent Citations (6)

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