3 replies to this topic

[chem400]

Dear all,
Can anyone please explain the term shut in tubing pressure in oil and gas drilling operation.
Thanks in advance,
With regards,
chem400

[Art Montemayor]

Chem400:

Any time you drill a hole into the earth's crust and hit an underground hydrocarbon deposit you will have invaded a potential high pressure zone of liquids + gases. Sometimes you may have a pure hydrocarbon liquid "play" - or source of your find. But even the liquid will have associated gas dissolved in it (mostly "low boilers" - like methane, ethane, propane, etc.). Other times your play may involve pure gas production - and in this case the pressures may be even higher.

If you study and research oil well drilling, you will find that the production "string" is a steel "tube" or pipe that is sometimes termed a "casing". At the top of the well (the "well head") you have a "christmas tree" - or a set of various block and throttling valves meant to do several things: block the flow of the produced fluids or throttle the flow. When you block the flow, the "christmas tree" (& every thing attached to it) MUST SUSTAIN and WITHSTAND the developed well head pressure resulting from the underground fluid reservoir. This pressure (which is usually in the thousands of psigs) is termed the "shut in tubing pressure" and is very important in knowing and identifying what it will be in order to design the Christmas Tree and most of the downstream treating equipment. Let me give you an example:

Most oil wells have field heaters, separators, and knock-out pots installed directly downstream of the well head christmas tree. This equipment is usually operating at a pressure lower than the shut in tubing pressure because the well head is usually being throttled (by a "choke" valve) in order to control the well's production rate. The choke valve may be manual or automatic in operation, but in any case it can fail in the open position and subject all equipment downstream to instant, maximum well head pressure (a.k.a., shut in tubing pressure). That means that you must prepare for this hazardous scenario and design your downstream equipment appropriately in order to avert a potential disaster.

I hope this explains the term and the role it plays in practical engineering design and operation.

[shukri]

Art Montemayor,
for flow tubing head pressure FTHP,is it refer to downstream of choke valve ? or just before the choke valve?

[milis]

I have similar problem to understand what is the different between SITP and FTHP.
My understanding until now is SITP is higher than FTHP. But FTHP (Flowing Tubing Head Pressure) is not on the downstream of choke valve.
SITP: maximum pressure that may exist in wellhead.
FTHP: pressure shown on Pressure Gauge on the wellhead during test and normal pressure.

Please someone correct my statement above, cause I am still not understand fully,.