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DOWNHOLE GAS LIFT AND THE FACILITY

DOWNHOLE GAS LIFT AND THE FACILITY. John Martinez Production Associates ASME/API GAS LIFT WORKSHOP. DOWNHOLE GAS LIFT AND THE FACILITY. SYSTEM COMPONENTS SYSTEM BACKPRESSURE – NUMBER OF WELLS – OPERATING FACTOR POWER INPUT AND SYSTEM BACKPRESSURE COMPRESSION OPTIONS DEHYDRATION OPTIONS

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DOWNHOLE GAS LIFT AND THE FACILITY

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  1. DOWNHOLE GAS LIFT AND THE FACILITY John Martinez Production Associates ASME/API GAS LIFT WORKSHOP

  2. DOWNHOLE GAS LIFT AND THE FACILITY • SYSTEM COMPONENTS • SYSTEM BACKPRESSURE – NUMBER OF WELLS – OPERATING FACTOR • POWER INPUT AND SYSTEM BACKPRESSURE • COMPRESSION OPTIONS • DEHYDRATION OPTIONS • MEASUREMENT, CONTROL, REMOTE TRANSMISSION • FLOW RATE STABILITY & GAS INJECTION RATE

  3. WHY IS GAS LIFT IMPORTANT? COURTESY EXXONMOBIL – MIKE JOHNSON

  4. WHY IS GAS LIFT IMPORTANT? COURTESY SHELL – JIM HALL

  5. FACILITY EQUIPMENT DRIVES GAS LIFT AND IS THE LARGEST CAPITAL EXPENDITURE • Onshore operator wanted more rig work and less wireline work • Standby compressor added due to the remote location

  6. FACILITY EQUIPMENT DRIVES GAS LIFT AND IS THE LARGEST CAPITAL EXPENDITURE • Offshore operator depends totally on wireline work • Excellent dehydration was required because gas had CO2

  7. SYSTEM BACKPRESSURE NUMBER OF WELLS OPERATING FACTOR • RATE PER WELL VARIES WITH SEPARATOR PRESSURE (SYSTEM BACKPRESSURE) • EXPLORATION TEST RATES AND PVT DATA • SIMULATE RESERVOIR BEHAVIOR • SIMULATE WELL DELIVERY • APPLY AN OPERATING FACTOR • SIMULATE WELLS NEEDED BASED ON BOTH RESERVIOR AND DELIVERY PERFORMANCE

  8. SYSTEM BACKPRESSURE NUMBER OF WELLS OPERATING FACTOR

  9. SYSTEM BACKPRESSURE NUMBER OF WELLS OPERATING FACTOR

  10. SYSTEM BACKPRESSURE NUMBER OF WELLS OPERATING FACTOR

  11. COMPRESSOR SUCTION AND DISCHARGE PRESSURE EFFECTS Discharge Pressure vs. Gas Lift Gas Requirement

  12. COMPRESSOR SUCTION AND DISCHARGE PRESSURE EFFECTS Suction Pressure vs. Gas Lift Gas Requirement

  13. COMPRESSOR SUCTION AND DISCHARGE PRESSURE EFFECTSOptimize Compression Horsepower (BHP)

  14. COMPRESSION OPTIONSOPERATING EFFECTS • WATER VAPOR IN THE GAS • REQUIRES MORE POWER FOR COMPRESSION COMPARED TO SIMULATING DRY GAS • HEAT DUTY FOR COOLERS GOES UP – EXCHANGER SIZE BASED ON DRY GAS IS TOO SMALL • TEMPERATURE OF GAS AND AMBIENT • AVERAGE USED IN DESIGN, ACTUAL OPERATING CAN BE SIGNIFICANTLY HIGHER • DRIVER DERATES, CANNOT SUPPY SUFFICIENT POWER • COMPRESSOR CYLINDER (RECIP) OR IMPELLER WHEELS (CENTRIFUGAL) CANNOT MOVE THE DESIGN RATE

  15. COMPRESSION OPTIONS - RECIPROCATING • Reciprocating compression applied to smaller rates • Good discharge pressure flexibility, limit on cylinder capacity • Matched with gas engine or electric motor Dresser Industries

  16. COMPRESSION OPTIONS - CENTRIFUGAL • Centrifugal compression applied to large rates offshore or internationally • Large gas throughput in a small package • Sensitive to gas composition changes • Mated with gas turbine or electric motor Solar Gas Turbine Dresser-Clark

  17. DEHYDRATION OPTIONS Triethylene glycol (TEG) is the common absorption dehydration method Mole sieves adsorb water vapor onto the surface in the bead

  18. DEHYDRATION OPTIONSWATER CONTENT BASED ON PRESSURE AND TEMPERATURE IS PREDICTABLEGPSA

  19. DEHYDRATION OPTIONSHYRATE CONDITIONS ARE PREDICTABLEGPSA

  20. MEASUREMENT, CONTROL, REMOTE TRANSMISSION • MEASURE INJECTION GAS LIFT GAS • SINGLE PHASE FLOW • STEADY PRESSURE (SHOULD BE) • MOST RELIABLE (COMPARED TO PRODUCTION SEPARATOR) • USE LOW POWER ACTUATED CHOKES USING SOLAR PANELS • RADIO TRANSMISSION OF GAS MEASUREMENT DATA, WELLHEAD AND CASING PRESSURE AND TEMPERATURE

  21. MEASUREMENT, CONTROL, REMOTE TRANSMISSION • INSTALL DOWNHOLE PRESSURE SENSORS IN NEW WELLS • MONITOR FLOWING BOTTOMHOLE PRESSURE • ADJUST GAS LIFT GAS RATE TO KEEP MAINTAIN THE FLOWING BHP (NOT CONTINUOUSLY) • MONITOR SUDDEN INCREASES WHICH INDICATE VALVE PROBLEM OR SHIFT IN POINT OF LEFT • TRANSMIT DATA TO OPERATIONS CENTER, PLATFORM OR EVEN HOUSTON, FOR ANALYSIS AND ADJUSTMENT

  22. FLOW STABILITY AND GAS INJECTION RATE • VALIDATED SIMULATION AND PRODUCION TESTS CAN DETECT UNDER PERFORMING WELLS DUE TO LIFT POINT SHIFT • COMPRESSOR OUTAGE AND FREEZING • SIMULATE VELOCITY AND FLOW PATTERN

  23. FLOW STABILITY AND INJECTION RATEGAS RATE PERMITTING SLUG FLOW, VELOCITY LESS THAN 5 FT/SEC

  24. FLOW STABILITY AND INJECTION RATEGAS RATE PROMOTES STABLE ANNULAR FLOW, VELOCITY GREATER THAN 5 FT/SEC

  25. FLOW STABILITY AND INJECTION RATEGAS RATE PERMITS SLUG/CHURN FLOW, VELOCITY ABOUT 5 FT/SEC

  26. GAS LIFT OPTIMIZATION DEPENDENT ON WELL PERFORMANCE AND FACILITY AVAILABILITY • COMPRESSION AVAILABLE >99% • EFFECTIVE DEHYDRATION • FREEZING IS A COMMON FIELD PROBLEM • 7 LB/MM (3 LB/MM IN COLD CLIMATES) • GAS SYSTEM DESIGN • LOW SUCTION PRESSURE • HIGH DISCHARGE PRESSURE • POWER REQUIRED PER BARREL IS LESS AT LOW SUCTION PRESSURE

  27. GAS LIFT OPTIMIZATION DEPENDENT ON WELL PERFORMANCE AND FACILITY AVAILABILITY • FIELD SIMULATION FOR DEVELOPMENT • RESERVOIR PRESSURE DECLINE AND WATER INCREASE • RATE VS INJECTION GAS DELIVERABILITY AT EACH RESERVOIR CONDITION • WELL COUNT FOR DIFFERENT OPERATING CONDITIONS • GAS MEASUREMENT • MAKE THE INJECTION GAS METER RELIABLE • MATE WITH LOW POWER CHOKE ACTUATOR AND REMOTE TRANSMISSION CAPABILITY • FLOW STABILITY • SIMULATE FLOW PATTERNS AND MATCH TO MEASURED AND OBSERVED BEHAVIOR • ANNULAR FLOW • VELOCITY > 5 FT/SEC

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