Gradients

[yasiobasio123]

Hi all

can you tell me how to calculate the gas7oil gradients and density from RFT data?? Say for example, if gas gradient 0.7 psi/m. How does we caculate this number 0.7?

Thanx

[kochichiro]

To calculate it you need the pressure and depth of its measurement, than you just dividing pressure on the depth. For example, you have 700 psi at the depth of 1000 m, so the pressure gradient would be 700/1000 = 0.7 psi/m.
Than, to convert it to density in g/cc, you need to multiply it by 0.3048 and divide by 0.4335275. Thus, (0.7*0.3048)/0.4335275 = 0.492 g/cc

If you have gradient in psi/ft, you just need to divide it by 0.4335275

[yasiobasio123]

Thanks you very much.
Can you tell me
1. What should be gradient for gas, oil and water?
2. How we can determine the densities of gas, oil and water?
thnaks

[jaideep]

pl find this excel-sheet attached. When u draw a graph find out slope of the straight line as 1/m or using equation m=(y2-y1)/(x2-x1). take inverse of m. this will give you gradient, depending on ur unit. if pressure is in psi and depth is in feet, u will get gradient in psi per feet. this u can convert in density which is easy to give u an idea if it is a gas, water or oil.

[yasiobasio123]

Thanks Jaideep, nice stuff.
If you have some other material related to petrophysics like a, m, n determination, Movable HC etc etc. Plz share here or any alternate?
Thanks again