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Adding local short description: "Component at the surface of a well that provides the structural and pressure-containing interface" (Shortdesc helper)
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[[Image:Wellhead-dual completion.jpg|right|thumb|Oil well Christmas tree]]
[[Image:Wellhead-dual completion.jpg|right|thumb|Oil well Christmas tree]]


The primary purpose of a wellhead is to provide the suspension point and pressure seals for the [[casing string]]s that run from the bottom of the hole sections to the surface pressure control equipment.
The primary purpose of a wellhead is to provide the suspension point and pressure seals for the [[casing string]]s that run from the bottom of the hole sections to the surface pressure control equipment.<ref>[http://www.glossary.oilfield.slb.com/Terms/enwiki/w/wellhead.aspx Schlumberger Limited, oil well]</ref>
<ref>[http://www.glossary.oilfield.slb.com/Terms/enwiki/w/wellhead.aspx Schlumberger Limited, oil well]</ref>


While [[drilling]] the oil well, surface pressure control is provided by a [[blowout preventer]] (BOP). If the pressure is not contained during drilling operations by the column of [[drilling fluid]], casings, wellhead, and BOP, a well [[blowout (well drilling)|blowout]] could occur.
While [[drilling]] the oil well, surface pressure control is provided by a [[blowout preventer]] (BOP). If the pressure is not contained during drilling operations by the column of [[drilling fluid]], casings, wellhead, and BOP, a well [[blowout (well drilling)|blowout]] could occur.
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Wellheads are typically welded onto the first string of casing, which has been cemented in place during drilling operations, to form an integral structure of the well. In exploration wells that are later abandoned, the wellhead may be recovered for refurbishment and re-use.
Wellheads are typically welded onto the first string of casing, which has been cemented in place during drilling operations, to form an integral structure of the well. In exploration wells that are later abandoned, the wellhead may be recovered for refurbishment and re-use.


Offshore, where a wellhead is located on the [[oil platform|production platform]] it is called a ''surface wellhead'', and if located beneath the water then it is referred to as a [[subsea]] wellhead or mudline wellhead.
Offshore, where a wellhead is located on the [[oil platform|production platform]] it is called a ''surface wellhead'', and if located beneath the water then it is referred to as a [[subsea]] wellhead or mudline wellhead.<ref>[https://www.croftsystems.net/oil-gas-blog/the-difference-between-a-wellhead-christmas-tree Croft systems, The Difference Between a Wellhead & Christmas Tree, August 29, 2014, by Meisa G]</ref><ref>[http://www.epmag.com/new-wellhead-design-speeds-operations-1364551 New Wellhead Design Speeds Up Operations, Schlumberger company, October 12, 2016]</ref><ref>[https://www3.epa.gov/region1/eco/drinkwater/pc_wellhead_protection.html EPA, Wellhead Protection Program ]</ref><ref>[https://www.geoilandgas.com/sfx SFX: Standardized Fatigue-Resistant Wellhead System Solution]</ref>

<ref>[https://www.croftsystems.net/oil-gas-blog/the-difference-between-a-wellhead-christmas-tree Croft systems, The Difference Between a Wellhead & Christmas Tree, August 29, 2014 ,by Meisa G]</ref><ref>[http://www.epmag.com/new-wellhead-design-speeds-operations-1364551 New Wellhead Design Speeds Up Operations, Schlumberger company, October 12, 2016]</ref><ref>[https://www3.epa.gov/region1/eco/drinkwater/pc_wellhead_protection.html EPA, Wellhead Protection Program ]</ref><ref>[https://www.geoilandgas.com/sfx SFX: Standardized Fatigue-Resistant Wellhead System Solution]</ref>


==Components==
==Components==
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==Functions==
==Functions==
A wellhead serves numerous functions, some of which are:
A wellhead serves numerous functions, some of which are:
# Provide a means of casing suspension. ([[Casing (borehole)|Casing]] is the permanently installed pipe used to line the well hole for pressure containment and collapse prevention during the drilling phase).
# Provide a means of casing suspension ([[Casing (borehole)|Casing]] is the permanently installed pipe used to line the well hole for pressure containment and collapse prevention during the drilling phase).
# Provides a means of tubing suspension. (Tubing is removable pipe installed in the well through which well fluids pass).
# Provides a means of tubing suspension (Tubing is removable pipe installed in the well through which well fluids pass).
# Provides a means of pressure sealing and isolation between casing at surface when many casing strings are used.
# Provides a means of pressure sealing and isolation between casing at surface when many casing strings are used.
# Provides pressure monitoring and pumping access to [[Annulus (oil well)|annuli]] between the different casing/tubing strings.
# Provides pressure monitoring and pumping access to [[Annulus (oil well)|annuli]] between the different casing/tubing strings.
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# [[International Standards Organisation|ISO]] 10423:2009 Wellhead and Christmas Tree Equipment
# [[International Standards Organisation|ISO]] 10423:2009 Wellhead and Christmas Tree Equipment


In general well heads are five nominal ratings of wellheads: 2, 3, 5, 10 and 15 (x1000) psi working pressure. They have an [[operating temperature]] range of -50 to +250 degrees Fahrenheit. They are used in conjunction with ring type seal gaskets.
In general well heads are five nominal ratings of wellheads: 2, 3, 5, 10 and 15 (×1000) psi working pressure. They have an [[operating temperature]] range of −50 to +250 degrees Fahrenheit. They are used in conjunction with ring type seal gaskets.


In general the yield strength of the materials range from 36000 to 75000 psi.
In general the yield strength of the materials range from 36000 to 75000 psi.


==See also==
==See also==
* [[Puteal|Puteal—Water well head]]
* [[Puteal]] — Water well head
* [[Pumpjack]]
* [[Pumpjack]]
* [[American Petroleum Institute]]
* [[American Petroleum Institute]]
* [[Drilling rig (petroleum)]]
* [[Drilling rig (petroleum)]]
* [[Christmas tree (oil well)]]


==References==
==References==
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==External links==
==External links==
{{Commons category|Wellheads}}
{{Commons category|Wellheads}}
*[http://www.glossary.oilfield.slb.com/Display.cfm?Term=wellhead Schlumberger Oilfield Glossary: wellhead]
*[https://glossary.oilfield.slb.com/en/terms/enwiki/w/wellhead Schlumberger Oilfield Glossary: wellhead]
{{Spoken Wikipedia|date=2021-06-09|En-Wellhead-article.ogg}}


[[Category:Oil wells]]
[[Category:Oil wells]]

Latest revision as of 07:18, 31 December 2024

For water well wellheads, see Puteal.

A wellhead is the component at the surface of an oil or gas well that provides the structural and pressure-containing interface for the drilling and production equipment.

Wellhead gas storage, Etzel Germany
Oil well Christmas tree

The primary purpose of a wellhead is to provide the suspension point and pressure seals for the casing strings that run from the bottom of the hole sections to the surface pressure control equipment.[1]

While drilling the oil well, surface pressure control is provided by a blowout preventer (BOP). If the pressure is not contained during drilling operations by the column of drilling fluid, casings, wellhead, and BOP, a well blowout could occur.

When the well has been drilled, it is completed to provide an interface with the reservoir rock and a tubular conduit for the well fluids. The surface pressure control is provided by a Christmas tree, which is installed on top of the wellhead, with isolation valves and choke equipment to control the flow of well fluids during production.

Wellheads are typically welded onto the first string of casing, which has been cemented in place during drilling operations, to form an integral structure of the well. In exploration wells that are later abandoned, the wellhead may be recovered for refurbishment and re-use.

Offshore, where a wellhead is located on the production platform it is called a surface wellhead, and if located beneath the water then it is referred to as a subsea wellhead or mudline wellhead.[2][3][4][5]

Components

[edit]

The primary components of a wellhead system are:

Functions

[edit]

A wellhead serves numerous functions, some of which are:

  1. Provide a means of casing suspension (Casing is the permanently installed pipe used to line the well hole for pressure containment and collapse prevention during the drilling phase).
  2. Provides a means of tubing suspension (Tubing is removable pipe installed in the well through which well fluids pass).
  3. Provides a means of pressure sealing and isolation between casing at surface when many casing strings are used.
  4. Provides pressure monitoring and pumping access to annuli between the different casing/tubing strings.
  5. Provides a means of attaching a blowout preventer during drilling.
  6. Provides a means of attaching a Christmas tree for production operations.
  7. Provides a reliable means of well access.
  8. Provides a means of attaching a well pump,

Design specification

[edit]

The oil industry specifications for wellhead systems (materials, dimensions, test procedures and pressure ratings etc.) are :

  1. API 6A, 20th Edition, October 2010; Specification for Wellhead and Christmas Tree Equipment
  2. ISO 10423:2009 Wellhead and Christmas Tree Equipment

In general well heads are five nominal ratings of wellheads: 2, 3, 5, 10 and 15 (×1000) psi working pressure. They have an operating temperature range of −50 to +250 degrees Fahrenheit. They are used in conjunction with ring type seal gaskets.

In general the yield strength of the materials range from 36000 to 75000 psi.

See also

[edit]

References

[edit]
  1. ^ Schlumberger Limited, oil well
  2. ^ Croft systems, The Difference Between a Wellhead & Christmas Tree, August 29, 2014, by Meisa G
  3. ^ New Wellhead Design Speeds Up Operations, Schlumberger company, October 12, 2016
  4. ^ EPA, Wellhead Protection Program
  5. ^ SFX: Standardized Fatigue-Resistant Wellhead System Solution
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