What influences GOR?

[Alex673]

Looking for way to do fun analysis with data available to me.

Once reservoir pressure drops below bubble point, we expect GOR to increase. Is that the only correlation between pressure and GOR (assuming all other in-situ conditions such as temperature remain the same)? I have production numbers and pressures from a conventional reservoir available to me. I was hoping to do more complicated analysis with the available info, but I'm not find any other relationships between pressure and GOR to explore. Are there any other relationships between GOR and pressure? I have seen the diagrams that show how GOR changes with reservoir drive types. I am not trying to estimate OOIP or anything like that, I'm just trying to study what influences GOR and the magnitude to which it influences GOR. In my current understanding, GOR is mostly a function of initial reservoir conditions, production strategy (like water drive) and reservoir pressure. Am I missing something?

 

[georgeverghese]

Apart from liftgas injection, GOR is higher for lighter crudes and less for heavier crudes. It is obviously directly related to the chemical composition of the reservoir fluid.

 

[LittleInch]

If you drop the reservoir pressure below bubble point all sorts of bad things start happening AFAIK.

GOR changes over the kife of a field as the higher ends will tend to be lifted out first. Then if you have gas injection or water injection that will mess with the GOR.

One field I knew it started at something like 800 then as the reinfected the gas gradually was predicted to rise to something like 15000, at which point it really became a gas field and they switched to make gas export the key output instead of the liquid....

GOR is measured at standard conditions so unless you change the fluid coming out of the hole then the pressure of the reservoir shouldn't make a lot difference.

But hey,,I'm not a reservoir engineer, aka rock doctor, so there may be some effect, but I've not come across many of them on this site so maybe a different one would be better for your question.