Wax Formation from Gas Fields

[KonstantinDns]

Working on a gas producing field with associate heavier hydrocarbon (condensate) production, I am trying to identify if there is a risk for wax formation from the condensate under high pressure/low temperature regimes. The only literature I found deals with waxes formed from petroleum mixtures of about C10 and above. My C10+’s are very limited, but I need to verify whether or not waxes might be a potential problem. Any ideas of a good starting point or how I can go about modeling wax formation in our system?

 

[MortenA]

Wax are paraffinic (n-alkanes) and soluable in polar and/or aromatic compounds. Since a high fraction of light components may help to keep a high fraction of wax forming components suspended in your reservoir this means that wax may be or become a problem.

This is a subject for a detailed reservoir study.

Best regards

Morten

 

[KonstantinDns]

Thanks for that Morten

1. The field has been operating for a few years and no wax formation problems have been detected. Is that evidence that the field is free from wax forming substances, or is there still the possibility to see some if we move to a higher pressure operating regime? Am I interpreting your answer correctly, that since we have been producing lighter HC’s, the wax forming ones might still be left in the reservoir?
2. Also, I was under the impression that waxes were heavier hydrocarbons C10+, and we have seen very low concentrations of C10+’s (<0.01 mol%). I would expect that this eliminates the possibility of wax formation.
3. Lastly, there are no aromatic compounds in the reservoir, and practically no polar ones either except traces of H2S (<3 ppm), CO2 (<0.16 mol%) and some iso-compounds. I would expect that since there is no significant amount of solute for the waxes, there shouldn’t be any in the reservoir.

Let me know your thoughts

 

[MortenA]

I cant really conclude on the fact that the field has been operating without wax formation - besides what would such a conclusion be worth to you?.

But if you know you reservoir composition - then a study should be possible.

But many things point in the direction that wax will not become a problem. So the way i see it you have to choose: Do you trust your own understanding of the subject or shall you recommend that a study is made? That is for you to decide.

Best regards

Morten

 

[KonstantinDns]

Thanks Morten, you've been of great help