Leak thread through control line

[monang77]

I am currently preparing for a leak sealing job on SCSSSV control line and wellhead cavity. Part of the assessment in evaluating the severity of leak in wellhead cavity and control line is to find the leak rate. I am struggling to understand how this leak rate should be measured. Some reference showed that it could be determined in gpm of fluid loss (mostly using hydraulic oil) injected into the control line or cavity, others described it in psi/min loss. Ideally the pressure in control line remains constant (that is at pressure required to maintain the SCSSSV flapper open) and in case of wellhead cavity the pressure ideally remains 0 psi (indicating integrity of the hanger seal), both indicates that both cases are static. So, my thesis so far is it is more appropriate to measure leak rate in terms of psi/min drop instead of gpm loss since pressure drop is measurable and flow rate loss is not. Any thought on my case are very much welcome. Cheers.

 

[A8yssUK]

a volumetric, pressure change per unit time vs a a gravimetric, weight change per unit time.

With the gravimetric you can get an actual amount of product/material being lost directly from the leak.
With the volumetric you cannot unless you know the actual volume of the pressurized system to a decent degree.

i.e. A 1 psi/min pressure drop "leak" on a 10000L tank is releasing much more product per minute than a 1 psi/min pressure drop on a 1L can.
but if the leak rate is 10g per minute on both... both have the same gravimetric leakage rate.

If in your thesis you'll compare two different solutions and they have the same pressure*volume, then either method is fine... but if your are comparing different systems were the pressure volume changes somewhat then your better using the gravimetric measurements.