Mean metal temperature during blowdown

[wilfully12]

Well not quite a blowdown:

Situation: I have a "reservoir of gas", actually a well of gas under pressure behind a choke. Those familiar with drilling it is the choke located after the choke line in a well intervention / kill situation.

After the choke the gas will flow to a mud/gas separator which operates at atmospheric conditions. I need to perform a calculation to see whether hydrate formation downstream of the choke is possible. Using a simple flash in Hysys, and a 50C upstream temp hydrate formation will occur - however this is effectively a blowdown and the pressure will reduce quickly.

The question is how do I account for metal mass at atmospheric temp (i.e. approx 20C) in the calculation. My feeling is to use the flash temp is too conservative. Any views?

Cheers

 

[dcasto]

The solution is velocity to keep hydrates washed away.

There isn't enough heat capacity in the steel in the system and heat transfer from the air is extremly little.

 

[MortenA]

Is it a gas well or is it just gas in the well string - and soon oil/water/gas will start to flow?

Best regards

Morten

 

[wilfully12]

Morten
It is an oil well, scenario being that gas has settled out at the top of the well for some reason (maybe a kick etc). This gives a limited volume of gas - maybe 500ft in the casing is realistic.

What were your thoughts?

 

[MortenA]

Well my thougts were that as soon as the liquid/gas mixture starts to fill the pipe then most of your worries would be over - because of the heat capacity in the liquid and the work generated when letting down the pressure for the liquid. So maybe a transient study of this is nescessary (or some rule of thumb exists - it is after all an "ancient" problem?.

Best regards

Morten