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How to Maintain High Producing Efficiency in Sucker Rod Lift Operations

How to Maintain High Producing Efficiency in Sucker Rod Lift Operations. Lynn Rowlan. What is High Efficiency?. Electrical Efficiency Total System Efficiency Should be greater than 50% Surface Efficiency should be greater than 80% Mechanical Efficiency

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How to Maintain High Producing Efficiency in Sucker Rod Lift Operations

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  1. How to Maintain High Producing Efficiency in Sucker Rod Lift Operations Lynn Rowlan

  2. What is High Efficiency? Electrical Efficiency • Total System Efficiency Should be greater than 50% • Surface Efficiency should be greater than 80% Mechanical Efficiency • Pump, Rods, Pumping Unit Size and Balance Reservoir Producing Rate Efficiency • Should be greater than 95%

  3. High Efficiency? High electrical efficiency, mechanical efficiency and reservoir producing rate efficiency requires: • Measurement of motor power, dynamometer data, the liquid level depth with casing pressure and a representative well test. • (Electrical efficiency, mechanical efficiency and reservoir producing rate efficiency) All three must be high for the well to be produced at optimum conditions.

  4. What Should be Known in Order to Analyze a Well? • Recent and/or Representative Well Test • Producing BHP & Static BHP • Dynamometer Data • Pump Capacity (or, Pump Card) • Energy Use • Wellbore Description • Artificial Lift System Description • Fluid Properties • Past History

  5. Analyze WellTo Determine Efficiencies: • Analyzes the well’s inflow performance to determine if additional production is available. ( >95% Eff. ) • Determines the overall electrical efficiency. • Analyzes the efficiency of the pump. • Analyzes the efficiency of the down-hole gas separator. • Analyzes the mechanical loading of rods and pumping unit. • Analyzes performance of prime mover.

  6. Well Flow Mechanism Productivity = Flow Rate/ Drawdown Flow Rate = 250 Bbl/Day Drawdown = 1000 – 500 = 500 psi PI= (250 bbl/day)/(500 psi) = 0.5 Bbl/day/psi 1000 psi 500 psi Flow

  7. Determine Well’s Potential using Inflow Performance = 357 Bbl/D = 500 Bbl/D

  8. Vogel IPR Relationship PBHP < 10% of SBHP to insure that the well is produced at more than 97% of maximum rate

  9. Power Measurement Equipment • Acquire: • RMS (thermal) motor current • Average (real) motor current • kW during a pump stroke cycle. • Three voltage sensing leads “RIGHT", • "CENTER" or • “LEFT". • 3. Two current sensors.

  10. Electric Power (kW) and Current (Amps)Input to the Motor over the time of One Pump Stroke

  11. Analyze System Efficiency 2 1 • Determine: • Input Kw • PR Hp • Pump Hyd Hp 3

  12. Example of Low Surface Efficiency Bad Tail Bearing Results in Low Surface Efficiency of 66.5% Before Surface Efficiency of 83.0% After Repair of Bad Tail Bearing After

  13. Motor Power and Electrical Analysis Cost $ Power System Efficiency

  14. Is the well being produced at its maximum production rate? Does a fluid column exist above the pump intake? Is the pump completely filled with liquid? Is low efficiency caused by incomplete pump fillage due to over-pumping the well or due to gas interference? Use Both Producing Fluid Level Survey and Dynamometer Analysisto Answers the Following Questions:

  15. Acoustic and Power Surveys ShowSystem Efficiency Less Than 35% Drawdown Dynamometer Your Job Tubing Leak ?

  16. Acoustic and Power Surveys ShowSystem Efficiency Greater Than 35% Drawdown Dynamometer Your Job

  17. Low Efficiencies of Sucker Rod Lifted Wells Are Often Caused by Partial Pump Fillage • More efficient operations and lower electrical power usage will result if wells are operated with a pump filled with liquid. • Full pump fillage also requires an efficient downhole gas separation that results in a full pump if sufficient liquid is present to fill the pump. • Full pump fillage generally requires controlling the run time of the pumping unit to match the pump capacity to the maximum well inflow rate.

  18. Gaseous Fluid Level Above Pump - Gas Interference ? Increase Efficiency by Improving Downhole Gas Separator Fo Well Gas Interference Fo Rods

  19. Fluid Level @ Pump - Fluid Pound? Timer or Pump Off Controller Candidate Fluid Pound

  20. Timers and Pump-off Control Systems • Both timers and pump-off control systems can be used to control a pumping unit motor • Timers are preset to turn the motor on and off at specific times • Pump-off Control systems shut down the motor when incomplete pump fillage is detected, then, turn the motor on after a preset elapsed time

  21. Pump-off Control System • Monitors pump fillage when the motor is operating • Shuts down the motor when partial pump fillage is detected • After a preset down time, starts the motor and again monitors pump fillage

  22. 15 Minute Percentage Timer • Reduce electricity demand charges • Relatively simple to operate • Relatively inexpensive • Should be considered for low cost intermittent pumping unit operation

  23. Optimize Efficiency of Well Before Installing TIMER or POC • Is the PBHP low compared to SBHP at all times? • Is the mechanical equipment properly loaded? • Is the pump full of liquid when liquid exists in the casing annulus above the pump?

  24. Startup Motor Power 0.7 seconds normal operation

  25. Power Usage DuringIntermittent Motor Operation Start up Pumped Off Full Pump Stopped

  26. HOW TO MINIMIZE ELECTRICITY USAGE? • Maintain a high pump volumetric efficiency: • Match pumping unit capacity with wellbore inflow. • Pump a Full Stroke of liquid by controlling run time with a POC or Timer • Eliminate Gas interference. • When System Efficiency is low, find and fix problem. • Mechanically/Electrically balance pumping unit. • Properly size pumping unit, rods and pump to match well loads. • On severely over-sized motors where surface efficiency falls below 50%, reduce motor size.

  27. Periodically Monitor Well’s Operations To Maintain Efficient Operations • Check pump for proper operation • Produce all available liquid from the Wellbore • Operate well with high volumetric pump efficiency • Use POC or TIMER to reduce run time if pump capacity exceeds production rate

  28. High Efficiency Reduces Equipment Operating Costs • Uniform loading of pump and pumping unit reduces maintenance. • Operating the pumping unit a portion of the time subjects the unit to less wear and tear. • Fluid pound should be minimized. • Reduced shock loading results in decreased rod buckling, pump wear, tubing wear, excessive rod loading changes and pumping unit vibration. • Reduction of shock loading reduces maintenance costs.

  29. Reduced Electrical Costs Reduced Mechanical Operating Expense. Increased in Oil and Gas Production. Longer Run Times Before Failure. Maintaining High Efficiency in Sucker Rod Lift Operations Results in:

  30. Questions?

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