6 replies to this topic

[Mohamed_Mamdouh]

Dear all,

One of our clients gave us a well composition and want us to determine its CGR and GOR. I completely understand that this should be determined by the reservoir engineer and lab personnel. But, this is just preliminary calculation for some specific reasons.

 

The question is that our team has been divided in determining the methodology:

1) The first team did it by taking the composition with put it directly in standard condition (on HYSYS). and then divided the STB of oil by the MMSCFD of gas.

 

2) The other team did it by adding a one stage flashing separator and then only the condensate was further reduced to the standard condition. Then they divided the STB of oil (from the tank) divided by the summation of both gas volumes from the separator and tank ( in MMSCFD). it is similar to the attached snapshot.

 

Can you please which one is correct and why. if possible to provide reference or book that would be so much helpful.

 

Thanks in advance.

 

 

[breizh]

Hi,

No document (snapshot) attached.

By the way why don't you ask a third party, let say SGS to perform the analysis from a real sample, it will provide all you need for your design (accuracy)?

Note: Not part of my expertise.

Breizh

[Pilesar]

Many chemical engineers are not in oil and gas. CGR = condensate to gas ratio. GOR = gas to oil ratio. STB = stock tank barrel (measure of oil at storage conditions). How different is the end result of the two methods? The way I read your description, the final result should be the same.

[shvet1]

 One of our clients gave us a well composition and want us to determine its CGR and GOR.  

 

Where exactly - christmas tree, separator, well tube, fiscal metering station? Which one is the point of client's interest?

 

Note that there exist dedicated software for such calculations, e.g. see Pipephase.

Edited by shvet1, 15 August 2023 - 12:44 AM.

[Mohamed_Mamdouh]

Hi,

No document (snapshot) attached.

By the way why don't you ask a third party, let say SGS to perform the analysis from a real sample, it will provide all you need for your design (accuracy)?

Note: Not part of my expertise.

Breizh

 

 I totally agree with you but the well is going to be drilled later this year and we are using composition of nearby well with few adjustments in the composition.

[Mohamed_Mamdouh]

Many chemical engineers are not in oil and gas. CGR = condensate to gas ratio. GOR = gas to oil ratio. STB = stock tank barrel (measure of oil at storage conditions). How different is the end result of the two methods? The way I read your description, the final result should be the same.

 

They yield totally different results because when putting the composition from the start at the standard condition, more gases will evolve. However, with intermediate flashing separator, less gases will evolve which means you will have more condensate at the tank.

[Mohamed_Mamdouh]

 

 One of our clients gave us a well composition and want us to determine its CGR and GOR.  

 

Where exactly - christmas tree, separator, well tube, fiscal metering station? Which one is the point of client's interest?

 

Note that there exist dedicated software for such calculations, e.g. see Pipephase.

 

 

I totally understand your point being a former surface well testing engineer, yet as a process engineer now we take the CGR directly from the client without determining exactly the point measured. 

 

And it should be fixed because the CGR (or GOR) is the parameters that the plant should be built upon.

 

We already used PVTp software (by Petroleum Experts) and it uses single stage flashing separator which yields different results when flashing the composition from the being to the standard condition.

 

I am just curious which should be the most efficient or correct methodology when determining the CGR.