4. Find the pore compressibility of a rock sample with a bulk volume of 40 cm3, a porosity of 23% and whose pore volume decreases by 0.10cm3 when a pressure of 800psig is applied on it. Questions 5. A reservoir with an outer radius of 450m, an inner radius of 2.5m, and a height of 20m experiences a drop in pressure from 6500 psig to 5000 psig. The initial porosity of the reservoir is 18.6%. What is the porosity of the reservoir after the pressure drop, given that the pore compressibility of the reservoir is 8.5105psig1 ? 6. (a) A core sample with a diameter of 1.5 in and a length of 2.0 in is saturated with brine solution of 0.26.m resistivity. The resistance of the core when fully saturated with brine is measured to be 1549.3. Calculate the formation factor F for this core. - (b) Assuming a=1 and =20.5%, what is the value of the cementation exponent m for this core