Page 59 - Introduction to Petroleum Engineering

ACTIVITIES 43

Model OOIP (MMSTB) Recovery Factor Reserves (MMSTB)
1 400 0.30
2 650 0.43
3 550 0.48
4 850 0.35
5 700 0.38

2.2 A. A geothermal power plant was able to provide 2000 MWe (megawatts
electric) power when it began production. Twenty years later the plant is
only able to provide 1000 MWe from the geothermal source. Assuming the
decline in power production is approximately linear, estimate the average
annual decline in power output (in MWe/yr).
B. Suppose the plant operator has decided to close the plant when the electric
power output declines to 10 MWe. How many more years will the plant
operate if the decline in power output calculated in Part A continues?
2.3 A. A coal seam is 600 ft wide, 1 mile long, and 15 ft thick. The volume occu-
pied by the fracture network is 1%. The volume of coal is the bulk volume
of the coal seam minus the fracture volume. What is the volume of coal in
the coal seam? Express your answer in ft .
3
B. If the density of coal is 1.7 lbm/ft , how many tons of coal are in the coal
3
seam?
C. The gas content G of gas in the coal matrix is 500 SCF methane per ton
coal
of coal. What is the total volume of methane contained in the coal seam?
Neglect any gas that may be in the fracture.
×
+
)
2.4 Porosity (fraction) is related to bulk density by ρ = (1 − φ ×( ρ ) ( φ ρ )
ma
b
f
where bulk density ρ is 2.40 g/cc from the density log, density of rock matrix
b
ρ is 2.70 g/cc, and fluid density ρ is 1.03 g/cc for brine. Estimate porosity.
ma f
2.5 A. A news article reported that 535 MMSCF gas could supply gas to 8150
homes for a year. Calculate the value of gas. Note: 1 MMSCF = 1 million
standard cubic feet.
Gas Volume (MSCF) Gas Price/Volume ($/MSCF) Value of Gas ($)
535 000 2.50
535 000 5.00

B. If the price of gas to the consumer is $5.00 per MSCF, how much does the
average home have to pay for gas each year?
Hint: First estimate the volume of gas in MSCF that is used by each
home each year, where 1 MSCF = 1000 SCF.

2.6 Typical energy densities for coal, oil, and methane are shown in the table.
The relative value of the energy in each material can be estimated by using