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  1. AreJay

    Gas Lift Issues - Mandrel issues

    Hello all, One of our subsea production wells slowly decayed to the point where it stopped taking gas lift. Numerous procedures have been completed including equalising the gas and production annulus and pumping HP N2 to try and lift at higher pressure. We have a proven flow path on the gas...
  2. AreJay

    Produced Water Backpressure

    That is exactly my thought... Surely if we have an extra head of liquid in the pipe then the force required to displace has doubled.
  3. AreJay

    Produced Water Backpressure

    Surely if the water is stacking up in the pipe then there will be a greater force required to displace the extra 20m of seawater in the pipe, hence with the greater force will require a slight raise in pressure?
  4. AreJay

    Produced Water Backpressure

    Afternoon all, Having a discussion offshore around a produced watere overboard line. We have our overboard line submerged in water up to a depth of 20m. We are wanting to extend the overboard line to 40m below the sea surface. Therefore I would imagine that we would have a greater back...
  5. AreJay

    Valve Cv

    Hi all, Been asked to look at a project of using a gas PCV isstead of a failed water LCV... I would presume no straight away due to differing characteristics however I have been asked to look at the Cv... Gas valve has Cv of 100.4 where as the original water valve has Cv of 393... would...
  6. AreJay

    Hydrates

    Yeah I ran the hydrate curver and it shows that the composition is in the hydrate region... mainly due to the temperature... the wells are so far away that the gas is so cold coming over the valves. I thought the whole point of a dehydration system would be to eliminate the risk of hydrate...
  7. AreJay

    Hydrates

    The producing wells are flowing at 40bar ish with a temperature of 40/50oC... it is the point where the gas lift is at the injection valve into the producing fluid where the gas is at its lowest temperature and will surely be at more risk of hydrate formation? What I cant understand is how all...
  8. AreJay

    Hydrates

    Hi all, Looking at the gas lift on a process and wondering about hydrates. The gas goes through dehydration before final compression where it is moved down to lift other wells. By the time the gas gets to the wells it has cooled down to around 7/8oC which bring the gas into its hydrate zone...
  9. AreJay

    Offline Pump - Ok to flow?

    Hi all, We have a situation of low pipeline pressure and our main export pumps are struggling to cope. We have pumps upstream to the export pumps which will be able to cope with the reduced pipeline pressure but the only flow path is through the main export pumps. Obviously not wanting to...
  10. AreJay

    Effectiveness of dew point hand calculations?

    Thanks for this I have re-calculated with the GPSA but still I have a different figure from HySys - I think it must be the reading from the graph... What does confuse me however is the offshore dew point analyser reads -20oC for that composition at 35 bar. HySys and my calculations would...
  11. AreJay

    Effectiveness of dew point hand calculations?

    K values were taken from Campbells gas processing volume 1 chapter 5 appendix a
  12. AreJay

    Effectiveness of dew point hand calculations?

    Hi all, I have been posting through the week about dew point calculations etc and I thank everyone for their help. What I would like to know is how effective are the hand calculation for a natural gas stream. Composition is as follows; Component Mol % CO2 1.39 N2 1.78 C1 77.25 C2 8.47 C3 6.10...
  13. AreJay

    Dew Point - Pressure Relationship

    Thanks for your help but I am still struggling to determine what I am doing... I have confused myself as I have my xi = 1 with my normal composition which I know is incorrect. I have assumed that the vapour fraction is equal to the compositonal anlaysis (which was taken at 35bar and 40degC)...
  14. AreJay

    Dew Point - Pressure Relationship

    I understand that thanks for your help... what is this Wi?
  15. AreJay

    Dew Point - Pressure Relationship

    I know have my yi (vapour fraction), xi (liquid fraction) and corresponding Ki for my composition at normal operating conditions of 110 bar and 40 DegC. What formula do I use to find the dew point of the gas? Do I need to vary the temperature to find new Ki values? Thanks
  16. AreJay

    Dew Point - Pressure Relationship

    Component Mol % Mol Weight Mol Fraction yi (Vapour Fraction) xi (Liquid Fraction) K CO2 1.39 44.00 0.0139 0.0139 #DIV/0! N2 1.78 28.00 0.0178 0.0178 #DIV/0! C1 77.25 16.00 0.7725 0.7725 #DIV/0! C2 8.47 30.00 0.0847 0.0847 #DIV/0! C3 6.10 44.00 0.061 0.061 #DIV/0! iC4 1.31 58.00 0.0131...
  17. AreJay

    Dew Point - Pressure Relationship

    Composition is constant, as is temperature... only change is the pressure
  18. AreJay

    Dew Point - Pressure Relationship

    Hi all, Looking at some hydrate curves for gas and was wondering if there is a quick formula for calculating the dew point with pressure change. Hydrocarbon gas in the line with dew point of -20DegC at 35bar. What would be the dew point at 110bar? Gas temperature is 40DegC. Thanks, Ryan
  19. AreJay

    Gas Cut Water

    yeah I am unsure how to approach the calculation. I know the gas in the water will cause the density to decrease which will mean the weight of water displaced is less than the weight of the vessel which will cause it to sink. I know it is a play on archemedies but unsure what to do.
  20. AreJay

    Gas Cut Water

    Hi all, I was wondering, when considering a vessel in the north sea, how much gas would it take to sink a boat? What would be the calculation method to work out when the water would have sufficient gas cut as to cause the boat to loose buoyancy? Thanks, R
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