Help. H2S VS CO2.

[VKir]

Hi Guys! 

Sorry for English. Friend (russian) of mine suggested me to use this platform for the chemical related question. Hopefully someone will understand and help me.

 

I'm working for oil and gas company and i'm going to drill an exploration well at the unknown area.

 

So, the situation is:

 

• Well will be drilled down to 4250m TVD/MSL (true vertical depth/mean sea level). Offshore with 1700m of water depth. Thus only 2550m of formation (earth, ground) will be drilled. We will drill thru the claystone, salt and thru the CARBONATE reservoir. 900m of reservoir full of gas.
• Top of reservoir at 3340m. Bottom at 4200m. Carbonate reservoir.
• Reservoir is absolutely permeable porous formation. Full of dry gas. Dry gas means Methane. CH4. Concentration is not known. Some small part of C2, C3, C4 can exist, but not to much. Based on the offset data (wells around, to far, but still some information) and geological information (comparison, seismic data and so on) we predict gas with 0.24 s.g. (specific gravity/water) at the reservoir conditions. Note: we use specific gravity, but not density. Methane 0.55SG / air at standard conditions. Or water related if we speak about gas at reservoir conditions. It's simplify other (pressures) calculations on the later stage.
• Reservoir conditions: 80 deg C, 444bar at 3340m and 464bar at 4200m. Gas 0.24sg/air.
• Sour gas. Up to 200-500ppm of H2S confirmed by other offset wells in the region. The presence of CO2 is likely in case of H2S occurrence (usual sour gas association in carbonate reservoirs).

Question: 

Is there any way to predict CO2 concentration depending on H2S concentration (%, ppm)?

 

Thank you guys for any help and explanations!

 

 

 

 

[M_GM]

It's too complicated and difficult question for this forum

[VKir]

Anyway, thanks for review!