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PID & Gas Lock Settings

Learn to optimize ESP performance, troubleshoot gas interference, and prevent shutdowns with expert PID and Gas Lock strategies.

ESP Current fluctuations (Motor Amps, or VSD Amps)

  • ​​​​Current is measured in Amps (Motor Amps or VSD Amps)

  • Current is measured at the VSD, the transformer ratio is used to calculate downhole motor current

  • Current is a measurement of how much work the ESP system is doing

  • Current is a relative indication of system loading

  • Large swings in current mean the system is oscillating between being highly loaded and lightly loaded. 

  • ESP systems like smooth, slow changing conditions.

  • Large current fluctuations are damaging to ESP systems, and can result in reduced reliability

  • Low relative amps compared to where the ESP usually runs can be an indication of gas interference.

  • Gas interference results in increased heat, and in the worst cases, gas lock leading to a shutdown due
    to high motor winding temperature

How Gas and Large Current Fluctuations Affects ESP Reliability
​    Pumps

  • Large current swings mean high cyclical loading that stresses the shafts, leads to fatigue, and can result in shaft breaks

  • High Heat causes failure in axial and radial AR bearing support and broken shafts

  • High heat and pressure differences can lead to collapsing diffusers

    Seals/Protectors

  • Cyclical loading results in cyclical heating and causes repeated expansion and contraction of the motor oil in the seals, leading to repeated losses of expanding oil through the vent plug.

  • Cyclical heating causes constant expansion and contraction of bags and can lead to bag tearing

  • High heat can result in mechanical seals (John Crane) seal failure

    Cable, MLE, Pothead, Wellhead Penetrator

  • Large current swings in an electrical systems is akin to large pressure swings in a hydraulic system.

  • High amp spikes find and damage weak points in the electrical system, and can lead to premature failures in electrical connections, splices, and insulation.

  • High temperature leads to degradation of insulation and electrical failures

    Motor

  • End coils are terminated into the windings and spliced into the motor leads causing a weak point

  • End coils wrap around the ends of the motor creating a high resistance point around the bend in the wire. 

  • High Temp leads to reduced lubricity of motor oil

How to Troubleshooting High Motor Current fluctuations?

1. Add Tubing Pressure

  • Make sure Ptbg at least 100-150 psi higher than Pcsg

  • Increasing speed can also help increase Ptbg

​

2. Enabling PID Mode

  • Always try PID first to line out the system 

​

3. Enabling Gas Lock Mode​

  • Only enable Gas Lock Mode as a last resort if PID is not solving the gas locking and high temp spikes

  • Almost always to be used in conjunction with PID mode. It is extremely rare to use Gas Lock Mode with Fixed Frequency.

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PID & Gas Lock Settings – Tubing Pressure
​​Add Back Pressure to Tubing
 

  • Back pressure helps reduce the size of gas bubble in the pump and helps condition the multiphase flow regime
     

  • Rule of Thumb: Keep Motor amp swings less than ~10A (Branden Pronk SWAG)
     

  • Ptbg should be set to at least ~100-150 psi higher than Pcsg
       e.g. If Pcsg = 100 psi, set Ptbg = 200-250 psi
     

  • If higher Ptbg is needed, Ptbg is rarely to exceed a maximum of ~500 psi

 

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Increased Tubing pressure to ~400 psi​
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Increased Tubing pressure to ~600 psi​
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PID & Gas Lock Settings – PID Mode
Enable PID Mode – Current (Amp) Feedback
​​​​​

  • Amp Feedback Target
    - The amp value where you want the ESP to run
    - Some vendors use VSD amps, some use Motor Amps
     

  • Polarity
    - Direct (If Amps increase = increase Hz, if Amps decrease = decrease Hz)
    - Reverse (If Amps increase = decrease Hz, if Amps decrease = Increase Hz)
     

  • Min Hz and Max Hz
    - The min and max speed that define the PID operating window 
     

  • Step Size 
    - The incremental Hz the PID loop changes at each step to try to get to the Amp Feedback Target (P = Proportional gain)
     

  • Step Time
    - Time between when the PID loop makes changes ( I = Integral Time)
     

  • Deadband %
    - If amps stay within this window = PID loop does not active
    - If amps go outside this window = PID loop activates
    ​

 

PID MODE - Setpoint Guidelines 
​​​​​​
  • Use these guidelines as a starting point to tune PID mode as needed
     

  • Amp Feedback Target
    - Start by picking the average (mean) of amp fluctuations.
    - Some vendors use VSD amps, some use Motor Amps
     

  • Polarity
    - ALWAYS use Reverse (If amps increase, decrease speed)
     

  • Min Hz and Max Hz
    - Start with ~10hz operating window (e.g. Min = 55 hz, Max = 65 hz)
    - Tighten the operating window as needed (~5hz-10hz window
     

  • Step Size 
    - For SLB, start with Step Size = 0.1hz - 0.2hz.
    - For vendor Specific PID, see Appendix
     

  • Step Time
    - Start with Step time = 1 sec.
     

  • Deadband %
    - Start with Deadband = 1-3%.

 

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PID & Gas Lock Settings – Gas Lock Mode
Enable Gas Lock Mode
​​​​​​

  • GL Low Amp Activation Setpoint
    - If Amps fall below this setpoint, GL mode will activate
    - If GL mode is activated and amps climb back above this setpoint, GL will deactivate and return to the normal operating mode
     

  • GL Low Amp Activation Time
    - Amps must fall below the GL Activation setpoint for this amount of time before GL mode will enable
     

  • GL Purge Frequency
    - The frequency that GL mode will drop to after amps has dropped below the Low Amp Activation Setpoint and Low Amp Activation Time
     

  • GL Cycle Time
    - Once GL mode is activated, this is the maximum time limit that GL mode will run at the Purge Frequency if the amps do not climb back above the - Activation Setpoint. GL mode will then cycle back to normal operating mode and try again.
     

  • GL Max Cycles
    - Maximum number of cycles the VSD will activate GL mode before shutting down
     

  • GL Steps
    - Ability to set multiple GL Purge frequencies for different consecutive gas lock cycles
    ​

 

GAS Lock Mode - Setpoint Guidelines 
​​​​​​
  • Use these guidelines as a starting point to tune PID mode as needed
     

  • GL Low Amp Activation Setpoint
    - Identify “Idle Amps” = Low amp period when PIP and/or Tm is rising
    - Setpoint should be 1-3A above Idle Amps
     

  • GL Low Amp Activation Time
    - Depending on ESP vendor, this setpoint can be set anywhere from 30 sec – 10 min
     

  • GL Purge Frequency
    - Start with 45hz
    - The goal of this setpoint is to reduce hz low enough that the pump cannot surface fluid, and allow fluid to fall back and flush out the gas
     

  • GL Cycle Time
    - Depending on ESP vendor, this setpoint can be set anywhere from 30 sec – 10 min
     

  • GL Max Cycles
    - Move this setpoint out of the way and use the maximum max cycles allowed
    - We do not want the ESP going down on max cycles trip
     

  • GL Steps
    - SLB: Does not have ability to set different gas purge frequencies
    - Other ESP vendors generally have the ability to set up to 3 different frequencies.

 

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© 2024 by Enerview

© 2024 by Enerview

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