Offshore Gas Release
Offshore Gas Release
(OP)
Hi guys,
Some help is required regarding a gas leak rate calculation. We had a gas release through a eqivilant hole diameter of 1mm. The release was from our export pipe which was pressured at 142bar and was being released to atmosphere. This lasted for a duration of ten minutes. I am comfertable doing this calculation and dont need any help.
What I do need help with is that when we started to depressurise the line we dropped the pressure from 142bar down to 38bar with the leak continuous. This was over a period of 1 hour. When the pressure went below 38bar the leak stopped so we think it is a passing seal. When calculating the leak rate for the hour with decreasing pressure, how is it done? Do I do the same calculation as with above and just extend the duration? Do I take the pressure drop over the time period and calcualte from there?
Thanks in advance
R
Some help is required regarding a gas leak rate calculation. We had a gas release through a eqivilant hole diameter of 1mm. The release was from our export pipe which was pressured at 142bar and was being released to atmosphere. This lasted for a duration of ten minutes. I am comfertable doing this calculation and dont need any help.
What I do need help with is that when we started to depressurise the line we dropped the pressure from 142bar down to 38bar with the leak continuous. This was over a period of 1 hour. When the pressure went below 38bar the leak stopped so we think it is a passing seal. When calculating the leak rate for the hour with decreasing pressure, how is it done? Do I do the same calculation as with above and just extend the duration? Do I take the pressure drop over the time period and calcualte from there?
Thanks in advance
R





RE: Offshore Gas Release
If you have a continious pressure measurement and a temperature measurement logged then you can just calculate the density in the gas phase multiply with the trapped volume and use that to calculate the release rate for each time step in the temperature log.
In all cases you would need the gas temperature - even if you wanted to calculate the release rate based on upstream conditions and a hole size. But "my" methode seems a lot easier if you have the data.
Best regards
Morten
RE: Offshore Gas Release
If you know the density at time n and time n+1 then the total loss from timestep n to timestep n+1 is dRho*total vlume - and then you could assume a steady release rate for each time step - if they are not too long compared to the release rate.
Best regards
Morten
RE: Offshore Gas Release
R
RE: Offshore Gas Release
this thread has the equation in english units