Page 511 - Petrophysics

PROBLEMS 479

PROBLEMS

1. Oil is flowing through a 10 cm core sample prepared for reservoir
rock properties evaluation at a rate of 20 cm3/s. The pump pressure
is 18 atm and the pressure at the end of the core chamber is 1 atm. If
the diameter of the core is 5 cm and oil viscosity is 0.45 cP, calculate:

a. Oil permeability of the core.
b. Pressure drop through the entire core if the pump rate is changed
to a new value of 13 cm3/s using permeability from (a).
c. The pressure drop in (b) if the core length is reduced to 75% of
the original length.
d. The diameter of the core to cause a pressure drop of 2 atm, if the
original length is reduced by half.
e. Apparent and actual velocity of oil if core has a porosity of 20%
and the pressure drop through it is 7 atm.

2. A core sample from a gas reservoir is to be tested for various
properties using nitrogen gas. The 12-cm-long core has diameter of
4 cm. Calculate:

a. Linear pressure drop across the core if gas flow rate is 5 cm3/s,
nitrogen viscosity is 0.012 cP, and core permeability is 50 mD.
b. Actual velocity of the gas if core porosity is 15%, irreducible water
saturation 20%, and inlet and outlet pressures are 10atm and
2 atm, respectively.
c. The average flow rate through the core, if linear pressure gradient
through core is 0.8 atm/s and outlet pressure is 2 atm.

3. A newly completed well in the center of an oil reservoir drains
60 acres at initial reservoir pressure of 3,000 psia, estimated from
DST. Following are the additional rock and fluid data in oilfield units:
P,f = 1,500 psia
K=30mD
h=50ft
r, = 7 in. = 0.58 ft
Bo = 1.15 RB/STB

p<> = 2.1 CP
Q = 0.25

a. Calculate the flow rate from this well assuming that well is flowing
at steady state.