The porosity of a core that was retrieved from a reservoir was measured in the lab and found to be 20%. Calculate the porosity under reservoir conditions if the overburden pressure is 4500 psi, the pore pressure is 1650 psi and the pore volume compressibility is 9x10€ pst-¹ A 160-acre and 100 ft thick reservoir has a porosity of 11%. The pore compressibility is 5.0 x 10- 6 (1/psi). If the pressure decreases 3,000 psi, what is the subsidence (ft)? Assume Cf=Cb
