pressure gradient

[yasiobasio123]

Hello,

please help me calculate the pressure gradient when we have MDT pressure data. is it like as below if not please correct?

Pressure gradient = (P2-P1)/(D2-D1)*0.3048 = .... psi/ft

If you have any excel sheet, please share.

Thank you

[vinomarky]

psi/ft is exactly that - a change in pressure per change in depth

So, if you have depth in ft and pressure in psi, gradient = (P2 - P1)/(D2 - D1)

If depth is in meters, then yes, multiply it by 0.3048

As a quick check to make sure you've got it all right, fresh water gradients will be around 0.433 psi/ft, Gas from 0.01 to 0.25 psi/ft (depending on the pressure/temp) and oil around 0.3 psi/ft for your 47 API type crude.

[yasiobasio123]

Thanks .... vinomarky

Another question when it is said "oil-wet" and "water-wet" core/reservoir, what does it actually mean, confuses me help ....?

[yasiobasio123]

Thanks .... vinomarky

Another question when it is said "oil-wet" and "water-wet" core/reservoir, what does it actually mean, confuses me help ....?

[vinomarky]

Oil Wet: Sand grains preferentially coat with oil, meaning high residual oil saturations and rapid water breakthrough

Water wet: opposite

[vinomarky]

Oil Wet: Sand grains preferentially coat with oil, meaning high residual oil saturations and rapid water breakthrough

Water wet: opposite

[yasiobasio123]

thank you
which porosity and permeability should one use when using MICP data for saturation height? Is it measured on end trims or come from routine core analysis plugs. If it is from routine core analysis, then there will be depth difference because mercury was done on end trims, please explain, many thanks

[vinomarky]

Whatever is representative to how you will be modelling it.

Will you be populating the model based upon Petrophysically derived porosity and a poro perm relationship? Then you need to ensure that the RCA you use represents the same porosity average to that which your tool resolution would yield at that location. If your sat/height function relationships is in turn a function of permeability (ie simple J function), then what permeability are you using? Klinkenberg corrected air perm on cleaned core? Perm of core at residual saturation? It all matters. For perms of sub 1mD, actual permeability in presence of residual water can be 10-100x less than to that of air.

You need to sit down and think it all through to ensure you are consistent, and that in the final analysis your Porosity x (1-Sw) yields appropriate hydrocarbon volumes, and that K x Kr yields appropriate productivity for your various phases under reservoir conditions.

[yasiobasio123]

Thanks you ....