H2S Partial Pressure.

[S.G]

Dear All,

We have a 6-inch flow line, oil flow rate is 5,000 bopd and GOR 1500 SCF/BBL. The flowing wellhead pressure is 500 P.s.i.g. what is the H2S partial pressure if the H2S is 20%?

 

[EdStainless]

Use the gas law.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[1503-44]

Its Dalton's law.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[shvet]

Engineers use applicable industry standards. Use ISO 15156-2 annex C "Determination of H2S partial pressure"

 

[pierreick]

Hi,
PH2S= Yh2S *P total.

https://fouladonline.ir/wp-content/uploads/2017/05/NACE-MR-0175-ISO-15156-2015.pdf

Pierre

 

[S.G]

Thank you, Pierre. Here is the latest edition, the 2020 edition.

 

[S.G]

Hi Pierre,

I really need your help on this: I calculated the partial pressure of H2S for systems with a gas phase. I now want the calculation for the following:

6-inch flowline
System pressure (Flowing wellhead pressure: 500 Psi)
GOR: 1500 SCF/BBL
Crude oil flowrate: 5,000 barrels per day
H2S content to up to 10% by mole

Regards,

 

[pierreick]

Hi,
It should be:
YH2S= 0.1
PT = 500+14.7 = 514.7 PSI abs
PH2S= 514.7*0.1 = 51.5 PSI

my 2 cents
Pierre

 

[georgeverghese]

Calc offered by @pierre assumes all 10% (mole) is in the vapor phase.
NACE considers partial pressure of the vapor phase only. Any H2S in the liquid phase is not relevant to vapor phase partial pressure of H2S.
So what is this 10% mole ; vapor phase, or total in liquid + gas ?

 

[S.G]

Thank you, Pierre.

Hello George,

The mole fraction of H2S in the gas is 10% - this is based on the gas composition / samples.

So, as mentioned above. Multiphase flowline:

6-inch flowline
System pressure (Flowing wellhead pressure: 500 Psi)
GOR: 1500 SCF/BBL
Crude oil flowrate: 5,000 barrels per day
H2S content to up to 10% by mole

 

[SJones]

@SG

1. The service is sour. You will only need calcs to differentiate between any CRAs that are being considered
2. Don’t post up copyrighted standards

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.