emulsions

[chowles]

I am dealing with an oil in water problem for an offshore gas rig. We appear to have an emulsion forming at the production seperator PCV. This emulsion then appears to travel all the way to the water skimmer. New pure condensate, and condi/water streams meet this emulsion stream on the way. I would like to know a bit more about what happens when the streams meet. Will a flow restriction be created? will the new stream tend to an emulsion as well?

A further problem is we believe the emulsion is being stabilised by the corosion inhibitor - has anyone had any experience of this - I am especially interested if they found a good solution!

Thanks

 

[gunnarhole]

Dear Chowles,

Congratulations, you have asked a monster of a question.

The short answer for the first question is that a PCV on the bottom of a HP separator is an excellent emulsion forming device. The type of emulsion, "oil in water" or "water in oil", has a tremendous effect on the viscosity of the fluid. The emulsion will have a much higher viscosity than either of the unmixed components, sometimes as much as 50 - 100 times. Once you get to 70% brine concentrations you generally have water external emulsions with viscosities approaching those of the brine. Talk this over with your Process Engineer.

For the second point, it is common for corrosion inhibitors to stabilize emulsions. Contact Baker Petrolite or whoever you buy your chemicals from and they will have information about this. They can explain the chemistry. They will also have demulsifiers that they can sell you

In a previous life I would have said that you need to put a hydrocyclone between the HP separator and the PCV. These days I would suggest that you consider it as an alternative to additional chemical treatment.

Regards,

Gunnar