Monday, 16 May 2011

Wellhead Equipment

Wellhead equipment are used in connecting the casing and  tubing  to an oil or gas pipeline. These are useful in suspending the casing strings and help seal the well. The casing is a permanently-installed pipe for lining the well hole to provide pressure containment and prevent collapse. The wellhead equipments are known as the flanged devices that are attached to the casing.
Wellhead equipments include a number of other components such as casing heads, casing spools, tubing head spools, tees, and crosses. The casing head is part of the connection between the casing and the wellhead equipment itself. Usually, many pieces of wellhead equipments are assembled together into one wellhead equipment that is called a "Christmas tree". These wellhead equipments are important for the tubes to be placed into the well while valves and chokes are used to control the flow of oil and/or gas at the surface. Wellheads and wellhead equipment may be located on offshore platforms, in sub-sea locations, or onshore.
A typical Wellhead Equipment -X-mas Tree Caps is shown below.

Casing Head Spool-Bottom Slip Connection characteristics:
(1) Connect surface casing by type WD slip.
(2) Adopt type BT secondary seal structure.
(3) Accurately calculate casing string's length is not necessary.
(4) Can not be affected by surrounding environment, climate, etc.
(5) Easy, rapid, safe and reliable in installation that can be applied to different sizes casing, such as: 30",20",13-3/8",12-1/4",9-5/8",7",5-1/2". It can also be applied to different sizes casing as: 13-3/8",9-5/8",7",5-1/2"etc.
A variety of bottom thread such as CSG, LCSG, BCSG, TM, for the connection between casing head and surface casing can be manufactured.

Casing Head Spool-Bottom thread connection
(1) Bottom of the casing head connects surface casing by various types of threads, such as CSG,LCSG,BCSG,TM,ETC.
(2) Convenience and rapid in installation, safe and reliable in operation.

Casing Head Spool-Bottom welded connection
(1)Bottom of the casing head connects surface casing by welding.
(2)There’s pressure test hole, which can test welding effect, in welding annular space.
Bottom can be connected to surface casing by the method of sleeve welding. Pressure testing holes are designed for the test of welding effect.
Applied Casing Program: 20", 13-3/8",9-5/8",7",5-1/2", etc.
Casing hanger is classified into two kinds,
  • The threaded (mandrel) and
  • The slipped; slip casing hanger consists of G, W, WD, WE and other types. WD hanger is applicable for connection of casing head and surface casing and keeps the slip closing the casing fast in use of outer force, W hanger adopts self-weight energized sealing structure and WE & G hanger is manual-energized sealing structure.


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