How to locate Water Oil Contact with good accuracy in reservoir?

[aminstorm]

I was thinking of how to locate Water Oil Contact with good accuracy in reservoir.

If anyone have a good idea , i would be please to know.

Thank u.

[vinomarky]

What do you mean by 'contact'?

Free Water Level? - If so, RFT/MDT pressure points through oil and water legs in a decent permeability reservoir should yield clear oil and water gradients, the intercept of which points to the FWL

Depth at which 90% Oil cut, 90% water cut, or any other arbitrary 'producing contact' limit - really only from tests or production

[i-anuar]

You could potentially see OWC from resistivity log and if properties are good should be close ot FWL.

Be aware that MDT/RFT in producing reservoir may give incorrect FWL (i.e shouldn't be used for this)

[06pg22]

I would rather add to vinomarky and i-anuar's, that both OH log and MDT before producing the well indicate almost same OWC. However, during production OWC may move upward, depending on the energy water is providing to produce the oil.
I dealt with a case where production from gas cap moved the oil rim-water contact 100 ft upwards in almost two months as indicated from OH logs in development well.

[i-anuar]

also there could be reservoir depletion through aquifer if nearby fields produced extensively.

i have seen one like that and we were struggling to define contacts from MDT (downdip of the structure) while logs of the well (in the crest of the structure) was giving too pessimistic volumes.

[Sequestrator]

From resistivity measurements. However, if you don't have in-situ measurements you're in trouble - if you have available a lots of SCAl data i.e. capillary pressure curves, you could average all the curves and adjust depths of measurement and then extrapolate to Pc i.e. depth at Sw=1. But this is only for rough estimates.