Fundamental Reservoir Engineering
1.1 Calculate the volume of 1 lb-mole of ideal gas will occupy at:
a) 14.7 psia and 60 ºF
b) 14.7 psia and 32 ºF
c) 14.7 plus 10 oz and 80 ºF
d) 15.025 psia and 60 ºF
1.2 A 500 cu ft tank contains 10 lb of methane and 20 lb of ethane at 90ºF
a) How many moles are in the tank?
b) What is the pressure of the tank is psia?
c) What is the molecular weight of the mixture?
d) What is the specific gravity of the mixture?
1.6 A 55,000 bbl (nominal) pipeline tank has a diameter of 110 ft and a height of 35 ft.
It contains 25 ft of oil at the time suction is taken on the oil with pumps that handle
20,000 bbl per day. The breather and safety valves have become clogged so that
vacuum is drawn on the tank. If the roof to withstsand 3/4 oz per sq in. pressure,
how long will it be before the roof collapses? Barometric pressure is 29.1 in.
Neglect the fact that the roof is packed and that there may be some leaks.
1.18 Experiments were mande on a bottom-hole sample of the reservoir liquid taken
from the LaSalle Oil Field to determine the solution gas and the formation volume
factor as function of pressure. The initial bottom-hole pressure of the reservoir was
3600 psia, and bottom-hole temperature was 160 ºF; so all measurements in the
laboratory were made at 160 ºF. The following data, converted to practical units, were
obtained from the measurements:
Solution gas [SCF/STB at
Pressure [psia] Factor
14.7 psia and 60 ºF]
3600 567 1.310
3200 567 1.317
2800 567 1.325
2500 567 1.333
2400 554 1.310
1800 436 1.263
1200 337 1.210
600 223 1.140
200 143 1.070
a) What factors affect the solubility of gas in crude oil?
b) Plot the gas in solution versus pressure.
c) Was the reservoir initially saturated or undersaturated? Explain
d) Does the reservoir have an initial gas cap?
e) In the region of 200 to 2500 psia, determine the solubility of the gas from your
graph in SCF/STB/psi.
f) Suppose 1000 SCF of gas had accumulated with each stock tank barrel of oil in
this reservoir instead of 567 SCF. Estimate how much gas would have been in
Fundamental Reservoir Engineering
solution at 3600 psia. Would the reservoir oil then be called saturated or
1.19 From the bottom-hole sample given in Prob 1.18
a) Plot the formation volume factor versus pressure
b) Explain the break in the curve
c) Why is the slope above the bubble-point pressure negative and smaller than the
positive slope below the bubble-point pressure?
d) If the reservoir contains 250 MM reservoir barrels of oil initially ¡, what is the
initial number of STB in place?
e) What is the initial volume of dissolved gas in the reservoir?
f) What will be the formation volume factor of the oil when the bottom-hole
pressure is essentially atmospheric if the coefficient of expansion of the stock
tank oil is 0.0006 per F?
1.23 Estimate the viscosity of an oil at 3000 psia and 130 ºF. It has a stock tank gravity
of 35 ºAPI and 130 ºF. It has a stock tank gravity of 35º API at 60 ºF and contains an
estimated 750 SCF/STB of solution gas at the initial bubble point of 3000.
1.24 Given the following laboratory data:
Cell Pressure Oil volume Gas volume in Cell Temperature
(psia) cell (cc) cell (cc) (ºF)
2000 650 0 195
1500=Pb 669 0 195
1000 650 150 195
500 615 700 195
14.7 500 44,500 60
Evaluate Rso, Bo, and Bt at the stated pressures. The gas deviation factors at 1000 psia
and 500 psia have been evaluated as 0.91 and 0.95 respectively.