1. The following information is available on a volumetric gas reservoir:
Initial reservoir temperature, Ti = 155°F
Initial reservoir pressure, Pi = 3500 psia
Specific gravity of gas, Yg = 0.65 (air = 1)
Thickness of reservoir, h = 20 ft
Porosity of the reservoir, φ = 10%
Initial water saturation, Swi = 25%
After producing 300 MMscf, the reservoir pressure declined to 2,500 psia. Estimate the areal extent of this reservoir.
2. The following pressures and cumulative production data^2 are available for a natural gas reservoir:
Reservoir Pressure, psia: 2080, 1885, 1620, 1205, 888, 645
Gas Deviation Factor, z
Cumulative Production, MMMscf: 0.759, 0.767, 0.787, 0.828, 0.866, 0.900
0, 6.873, 14.002, 23.687, 31.009, 36.207
a. Estimate the initial gas-in-place
b. Estimate the recoverable reserves at an abandonment pressure of 500 psia. Assume za = 1.00.
c. What is the recovery factor at the abandonment pressure of 500 psia?
