Methanol Injection & Water Disposal Contamination

[nashc0]

I understand that when methanol is injected into a produced stream of water and oil, and that stream is separated by gravity, that a certain amount of the methanol will end up in the water since it is a polar molecule and is fairly close in molecular weight, etc. Does anyone know of any studies that have been done to estimate what portion of methanol under various conditions can be expected to end up in the water phase versus the oil phase? I am working on some options for preventing hydrate formation, and I want to see what the environmental impact of methanol injection under our conditions would be.

Any help is appreciated.

Clayton Nash
Facilities Engineer - BP

 

[kenvlach]

In environmental work, the Octanol/water partition coefficient is often used to estimate the distribution of a chemical between the organic & aqueous phases. There are EPA tables of P_ow for different chemicals, with

P_ow or K_ow = C_n-octanol/C_water

Composition values in g/L are used.

http://www.crwr.utexas.edu/gis/gisenv99/class/risk/lecture/Lect4/Fate.html#octonal

For methanol (highly polar), K_ow = 0.17

Of course, actual data for the specific organic solvent is better, especially as nearly all K_ow values are for 25^oC. I expect chloride in the aqueous phase will lower K_ow values for polar chemicals.

 

[MortenA]

Clayton:

On the hydrate issue - remember that its only the MeOH in the water phase that does much good against hydrate disscociation temperature depression. The Hammerschmidt equation is specifically only valid for the amount of inhibitor that ends up in the water phase.

I dont know where you operate - but if you inject your produced water the MeOH wont do much damage.

Best regards

Morten