Casing and tubulars or Tubing

[ozyjo]

Hello, I am new to Petroluem drilling. I would like to know the difference between a tubing and casing. Thanks

 

[cmlpetro]

Check out the Schlumberger glossary, both tubing joint and casing are defined.

http://www.glossary.oilfield.slb.com/

 

[ozyjo]

Thanks it was very helpful

 

[zdas04]

Interesting that there was a definition for "casing", but not for "tubing". The casing definition was a good one though, basically the difference is whether the tubular goods are cemented into the wellbore or not. Good distinction since I go to some operations with 4-1/2 tubulars cemented into the hole as casing and other operations with exactly the same designation tubulers hung off as tubing.

David

 

[johnsmith2]

I think casing with diameter, while tubing with smaller diameter.

 

[ozyjo]

I initailly felt that difference maybe in the wall thickness of casing and tubulars though I also thought it should be that casing are cemented into the wellbore while tubulars serve as conduit for fluid flow in the well.

 

[cmlpetro]

"casing are cemented into the wellbore while tubulars serve as conduit for fluid flow in the well"

Thats a great definition.


Casing is cemented in the open hole so that crossflow of fluids will not occur between different reservoirs.

Tubing is run in the cased hole to decrease the cross sectional area of flow to increase velocity and prevent liquid loading.

 

[johnsmith2]

sorry typo

I think casing with "larger" diameter, while tubing with smaller diameter.

 

[DrillerNic]

According to the API, the only difference between casing and tubing is the diameter- from memory, if it's bigger than 5", it's casing, if smaller it's tubing.

So for example, when I install and cement 4-1/2" casing, I turn to the tubing section of API 5CT for its size and performance data.

Both tubing and casing are OCTG (oil county tubular goods). Colloquially tubing is the tube the oil or gas flows up and is supended inside the casing that lines the wellbore. However, I've seen 7" tubing and 4" casing in different wells, and uncemented casing (horizontal liners anyone?) and cemented tubing (OK that was a cock up while we were trying to do a water shut-off but still....)