12
USER GUIDE
PCS 4000
SINGLE WELL CONTROLLER
Features for Closing the A-Valve
LOW FLOW RATE =
☛
SET 23
If you want the controller to close the A-valve when the
sales line’s flow rate falls below a specified value, set
the LOW FLOW RATE. For example, if you set the LOW
FLOW RATE to 300, the controller closes the A-valve
when the flow rate falls below 300 mcf. This function
keeps the flow rate from dropping to the point where
liquids fall back into the tubing.
You can use this function by itself or together with
CRITICAL FLOW K FACTOR.
PCS provides a Microsoft
®
Windows
®
critical flow
calculator program to help calculate LOW FLOW RATE
and CRITICAL FLOW K FACTOR values for your well.
For more information, call your PCS sales and service
representative.
Note:
If you have metric (SET 33) on, the flow rate unit of
measurement is thousand cubic meters (E
3
M
3
).
CRITICAL FLOW K FACTOR =
☛
SET 25
If you want the controller to close the A-valve when
the sales line’s flow rate falls below a critical flow rate
computed with Turner’s equation, you can set both the
LOW FLOW RATE and the CRITICAL FLOW K FACTOR.
The K factor is a gas constant that allows for fluctuating
sales line pressures. These 2 functions together keep
the flow rate – in combination with fluctuating sales line
pressure – from dropping to the point where liquids fall
back into the tubing.
Example:
Set the CRITICAL FLOW K FACTOR to 65506.
Set the LOW FLOW RATE to 300 mcf.
The controller closes the A-valve when the flow rate
falls below 300 mcf
or
the critical flow K factor falls
below 65506.
B LOW FLOW RATE =
☛
SET 35
If you want the controller to open the B-valve during
A OPEN TIME when flow rate falls below a specified
value, set the B LOW FLOW RATE.
Example:
Set the B LOW FLOW RATE to 50.
The controller opens the B-valve when the flow rate
falls below 50 mcf.
B LOW FLOW DELAY TIME =
☛
SET 36
If you are using B LOW FLOW RATE, you can use B LOW
FLOW DELAY TIME to keep the controller from opening
the B-valve if there is a brief drop in flow rate.
Typical settings for B LOW FLOW DELAY TIME are 1 to 2
minutes.
Features for Special Circumstances
CASING DROP PRESSURE =
☛
SET 20
CASING DROP PRESSURE is used in these 3 situations:
The wellhead configuration affects the plunger travel
into the lubricator. The plunger arrives but the plunger
arrival sensor can’t sense the plunger arrival every
time. Use CASING DROP PRESSURE as a backup.
A well is intermitted without a plunger. CASING DROP
PRESSURE allows the well to flow if it unloads.
The plunger arrival sensor malfunctions, and the
operator does not have an immediate replacement.
Use CASING DROP PRESSURE as a temporary fix.
Note:
If the arrival sensor malfunctions, the CASING
DROP PRESSURE function prevents the B-valve from
opening if the well is unloading. This may save wear
and tear on the plunger.
If the casing pressure drops by the specified value, the
controller starts the DELAY TIME (SALES) countdown
even if it does not receive an input from the arrival sensor.
Note the casing pressure at the moment when the
1
A-valve opens, for example, 400 psi.
Note the casing pressure when the plunger surfaces,
2
for example, 300 psi.
Set the CASING DROP PRESSURE to the difference
3
between these 2 values (400 – 300 = 100). Add an
additional 10-15 psi, for example, 115 psi.
The additional 10-15 psi makes sure the plunger surfaces
before the CASING DROP PRESSURE is reached. If
the CASING DROP PRESSURE replicates a plunger
arrival too closely, it may be reached before the plunger
surfaces. The Plunger Travel Time History then shows a C
when the CASING DROP PRESSURE is reached.
Example:
LAST PLUNGER- 0
C 0:10:20
