Page 81 - Introduction to Petroleum Engineering

ACTIVITIES 65
fluid density when oil density is 0.9 g/cc, water density is 1.03 g/cc, and water
saturation is 30%.
Hint: Convert water saturation to a fraction and calculate oil saturation from
S + S = 1.
w
o
3.3 A. Use the real gas law pV = ZnRT to find a general expression for gas
formation volume factor B . Use subscripts “s” and “r” to denote surface
g
conditions and reservoir conditions, respectively.
b. Calculate B using {p = 14.7 psia, T = 60°F, Z = 1} and {p = 2175 psia,
g
r
s
s
s
T = 140°F, Z = 0.9}. Express B as reservoir cubic feet per standard cubic
g
r
r
feet (RCF/SCF).
C. Calculate B using {p = 1 atm, T = 20°C, Z = 1} and {p = 15 MPa,
r
s
g
s
s
T = 60°C, Z = 0.9}. Express B as reservoir cubic meters per standard
g
r
r
3
3
cubic meter (Rm /Sm ).
D. What is the difference between the calculation in Part B and the calculation
in Part C?
3.4 A. A well produces 1000 MSCF gas and 400 STB oil. What is the GOR in
MSCFG/STBO? Note: 1 MSCFG = 1 MSCF gas and 1 STBO = 1 STB oil.
b. Assuming all of the gas is solution gas (no free gas), is the oil a black oil
or a volatile oil?
3.5 Suppose bubble‐point pressure of oil is 2400 psia in a reservoir with 70% oil
saturation and 30% irreducible water saturation. Is the reservoir saturated or
undersaturated at an initial reservoir pressure of 2515 psia?
3.6 A set of saturated oil fluid property data is given below as a function of pressure
P. Bubble‐point pressure PBO is 2014.7 psia. The undersaturated oil viscosity
MUO is approximated as a line with slope MUOSLP from bubble‐point
pressure (PBO) to reservoir pressure above PBO. The undersaturated oil
formation volume factor BO is approximated as a line with slope BOSLP from
bubble‐point pressure (PBO) to reservoir pressure above PBO.
A. Calculate oil viscosity MUO at 3000 psia pressure.
b. Calculate oil formation volume factor BO at 3000 psia pressure.
C. Calculate solution gas–oil ratio RSO at 3000 psia pressure.
PBO (psia) MUOSLP (cp/psia) BOSLP (RB/STB/psia)
2014.7 0.000046 –2.3 ×10 –5
P (psia) MUO (cp) BO (RB/STB) RSO (SCF/STB)
14.7 1.04 1.062 1
514.7 0.91 1.111 89
1014.7 0.83 1.192 208
1514.7 0.765 1.256 309
2014.7 0.695 1.32 392
2514.7 0.641 1.38 457
3014.7 0.594 1.426 521
4014.7 0.51 1.472 586