Week 8 Lab Part 1: Gas Reservoir Depletion and Orifice Meter and Critical Flow
Part 1. Gas Reservoir Depletion
Objectives:
 Obtain a basic understanding of gas material balance concepts.
 Be able to estimate original gas in-place given pressure depletion and gas
cumulative production data.
Equipment: Laboratory set up; safety equipment (covered shoes, safety goggles; no
shorts)
Discussion:
 Discuss the objectives of the lab.
 Discuss the uses of the P/Z versus cumulative production plot.
Setup:
1) Close outlet valve from tank and fill with compressed air to 40, 50, 60, and 70 psi
(each group will need to do a different starting pressure, but combine all different
starting pressures for lab report).
2) While tank is filling, roughly measure tank dimensions so that tank volume can be
estimated and draw a sketch of the experimental apparatus.
3) Record the specifications of flow rate measurement device; model, size, type of meter
and the units of the output.
4) Reset the cumulative gas volume reading at zero. Your TA will guide you on how to
complete this part of the experiment.
Procedure:
1) Once tank is filled, close inlet valve to the tank and record the initial pressure.
2) Designate a pressure gauge reader, a cumulative flow meter reader, a valve operator
and a recorder from the members of your group.
a. Open the outlet valve and vent contents of tank to the room through the
flow meter while recording tank pressure and cumulative gas flow.
Deplete the pressure in the tank in 5 psi decrements and record the
cumulative flow out of the tank at each pressure decrement (see table on
next page). Take at least 7 readings.
b. After taking measurements, close the tank outlet valve and record the
stabilized shut-in tank pressure.
Report:
1) Briefly discuss the experimental apparatus (show sketch), procedures and your
group’s recordings.
2) Construct a material balance plot for the tank by plotting P/Z versus cumulative gas
produced (P must be in absolute pressure, not gauge pressure). What is the initial gas
in-place in the tank? Compare this value with the volume of the tank you computed
in the setup section of this lab. (Assume ideal gas behavior).
P[psig]
Cumulative Production[scf ]
TA___________
Lab Week 8 Part 2: Orifice Plate and Choke Performance
Objectives:
 Identify and describe different components of Orifice Plate Gas Meter.
 Determine gas flow rates through orifice plates of different sizes.
 Determine changes in pressure drops as a function of flow rate, plate diameter and
measurement location.
 Determine how to optimize flow rate measurement using orifice plates.
 Learn how to change out orifice plate in a flowing gas line
A = air/gas entrance from upstream choke
B = pressure taps
C = orifice plate assembly
D = exit to drain
E = downstream choke to control back pressure & flow
rate
B
B
B
E
E
x
x
p
p
l
l
a
a
PART A: Measurement of Gas Flow through Fixed Orifice
Plates
i
i by Measurement of
Pressure Drop
n
n
Procedure:
t
t
You will record pressure drops across two different
orifice
h
hplates on the marooncolored flow loops. Make sure you know the size of
e the orificeein each loop.
d
d
As usual, safety glasses, close-toed shoes, long clothing
are
required
in the lab at all
i
i
times.
f
f
f
f
 Inspect all components from compressed eair inlet toe roof discharge pipe
connection. Pay special attention to differential
pressure
r
r measurement quick
connects.
e
e
 Check that all valves are closed and connections
are
secure.
n
n
 Record pressure at inlet and outlet.
c
c
 Open valves to introduce gas flow into one of ethe three flow
e loops. Start with the
master air valve. Adjust flow with the adjustable
choke—record
choke settings for
s
s
each flow rate you use.
 Record pressure at inlet and outlet and volumetric flow rate.



Increase the flow rate and record new pressure measurements. Continue for 5
different flow rates.
Notify your TA that you have completed your first set of runs.
Repeat steps 2-7 for another size orifice plate. Do the experiment for two different
size orifice plates (0.5, 1 inch diameter plates). Transfer the quick connect
pressure gauge from flow loop to flow loop before proceeding.
PART B: Orifice Meter (can be changed while flowing) – Done as Demo
Procedure:
 Close the air inlet valve.
 Bleed the line pressure down through the fixed orifice plate flow loop.
 Isolate the flow line incoming to the senior orifice meter.
 Follow the supplemental orifice plate manual for the removal and replacement of
the orifice plate.
 Ensure that the orifice meter is not leaking after replacing the plate before the next
section.
Required:
1. Calculate the volumetric flow rate based on pressure drop across orifice plate.
2. Use the orifice pressure calculator (Computer program located only in 301) to
compare the recorded flow rate to the calculated flow rate.
3. Compare both to flow rate recorded by Coriolis meter during experiments
4. Discuss/explain differences among the different flow measurements
Answer the following (and do for downstream pressure measurement at two locations (1)
at the plate (using the quick-release connectors to measure pressure downstream of the
plate), plus (2) the permanent Omega gauge further downstream.
5. You may have to use different equations for computing flow rates when
measuring downstream pressure at the orifice and further downstream. Why are
the downstream pressures different at the two locations. Why are the calculations
different?
6. What happens to the pressure drop as the flow rate increases?
7. What happens to the pressure drop as the orifice plate opening increases in size?
8. Are the locations of the pressure taps appropriate?
i. How important is the location of the pressure gauge that is upstream of the
orifice plate? Why?
ii. How important is the location of the gauge that is downstream of the
orifice plate? Why?
9. Plot Pressure drop vs. flow rate for both orifice plate diameters.
10. Plot Pressure drop vs. orifice plate diameter at constant flow rate for all flow
rates.
11. Describe qualitatively the differences you saw between the pressure drops on the
orifice plate.
12. In Appendix A, you are given a typical discharge coefficient. Why this is a
reasonable value?
13. Imagine this being field data and the flow rate was not given, and in order to
determine gas production you had to calculate flow rate at the given pressure
drops. Use the appendix below to calculate the flow rate and compare it to the
actual flow rate on a plot of calculated vs. actual flow rate for all orifice plate
diameters along with a trend line of y=x. Calculate hw by calculating height of
equivalent hydrostatic pressure.You will find useful information in the readings
referenced in Appendix B, but don’t feel limited to those readings only. Please
reference those readings or any other material you use in your report.
Data Sheet
PART A
Pressure (Inlet) PSI
Valve close
Pressure ( Outlet) PSI
Valve is close
0.50” orifice plate
Volumetric
Choke
flow rate (units)
Setting
(64ths)
Inlet
Pressure, psi
Outlet
Pressure, psi
Pressure Drop,
psi
hw, inches
0.75” orifice plate
Volumetric
Choke
flow rate (units)
Setting
(64ths)
Inlet
Pressure, psi
Outlet
Pressure, psi
Pressure Drop,
psi
hw, inches
Inlet
Pressure,
psi
Outlet
Pressure, psi
Pressure Drop,
psi
1.00” orifice plate
Volumetric
Choke
flow rate (units)
Setting
(64ths)
hw, inches
TA_______________________________________
Appendix A
sc
Cd = 0.6 as standard.
Appendix B: Choke Flow
Orifice plate and choke flow are similar. Below is extracted a discussion of flow through
a choke from PPS (pp. 228-9). There is more discussion in PPE (Ch. 5). There are
differences in the equations used for nozzle choke and orifice plate. Note especially the
differences in discharge coefficient.
what they are. Ask Frank Platt for help.