Question 1
A-
BC-
Define the skin factor, what does it physically mean, and what are the
different ways of representing the skin factor. What are their
limitations?
What are the major objectives of interference test?
What are the parameters influencing the permeability calculation?
Question 2
Write the line source solution. What are the assumptions used in its
derivation. What are the limitations on its use? Write the log
approximation to the line source solution and state when it is applicable.
Question 3
On the following log-log plot identify the lines:
Line one
WBS
IARF
Sealing fault
Pseudo-steady state
Line two
WBS
IARF
Sealing fault
Pseudo-steady state
Line three
WBS
IARF
Sealing fault
Pseudo-steady state
Question 4
Characteristics of constant wellbore storage effect include: (select two)
a. P is a linear function of time
b. Unit slope straight line on the log-log plot
c. P is a linear function of log (time)
Question 5.
What is the characteristic of Infinite Acting Radial Flow in a build-up:
(select one)
a. P is a linear function of log(time)
b. P is a linear function of log(tp+ delta t / delta t)
c. We see a unit slope straight line on the log-log derivative
Question 6.
What are the characteristics of linear flow (select two)
a. P is a linear function of time
b. P is a linear function of the square root of the time
c. a ½ unit straight line on the log-log derivative
Question 7
A drawdown test was conducted for a new producing well. The well and
fluid parameters are as follows:
Porosity = 0.15
Well Radius = 0.25
Pay zone Thickness = 30 ft
Formation Volume Factor = 1.3 rbbl/STB
Viscosity = 1.08 cp
Production Rate = 2000 STB
It is required to determine the following:
A- Initial Reservoir Pressure
B- Storage Coefficient
C- Reservoir Permeability
D- Skin Factor
E- Pressure drop due to skin
F- the product (Φct h) from well tests data. Compare with given data
Question 8
A- Given the following pressure-time data. Use type curve matching
method to analyze this data. Use Bourdet derivative algorithm to compute
the logarithmic pressure derivative in a number of points to help you
identify the proper curve. Estimate all parameters that can be determined
from this analysis.
B- If the average reservoir pressure is 3500 psia, compute the Flow
Efficiency for this well. If the flow efficiency is to be increased by 30%.
Would the well be damaged or stimulated after the treatment (compute
the corresponding value of skin).
Given data:
Initial reservoir pressure
5000 psia
zone thickness
35 ft
wellbore radius
0.25 ft
reservoir porosity
0.18
Total compressibility
3 x 10-6
Viscosity
4 cp
Oil formation volume factor
1.1 rbbl/STB
Question 8 (optional with Question 7)
A well is produced at a constant rate of 4000 STB/D for a period of 10
hrs and is then shut in for 30 hours, giving the pressure buildup data
tabulated below.
Time
Pwf (psi)
(hours)
5
5127.4
10
5098.
11
5898.4
12
5924.1
13
5937.8
14
5946.9
15
5953.4
16
5958.4
17
5692.4
18
5965.6
19
5968.3
20
5970.6
22
5974.3
24
5977.1
26
5979.4
28
5981.2
30
5982.8
Additional data determined are:
Pi = 6000psi
µ = 0.5
cp
Ф = 0.20
Ct = 20x10-6 psi-1
B = 1.5 rb/stb
h = 100 ft
rw = 0.50 ft
Compute the following:
ƒ Draw the pressure build up plot (Horner plot)
ƒ Slope
ƒ Permeability
ƒ Skin factor
ƒ Pressure drop due to skin factor and the effective radius
ƒ Productivity index (B/D-psi), the flow efficiency, damage ratio and
damage factor.