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ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Unloading Water fromOil Wells Using Air
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Background
Drilling horizontal wells in the Rocky Mountain Region
Drilling operation incurred high drilling fine and fluid losses in formation
Operator was using rod pumps to produce wells; Severe plugging of pumps and tubing with drilling fines common
– RESULT - repeated workovers and had a consequential cost impact
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Clean Out Issues
Before producing wells with rod pumps, operator needed a way to
– clean out drilling fines
– unload large volumes of water from the formation
Different types of artificial lift methods were considered
Gas lift was determined to be best lift method when considering large volumes of fluid, producing fines, and cost
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Injection Gas Source
Natural gas was not available in this area Screw compressor availability; used in this
area for underbalanced drilling Air considered as injection source Spontaneous combustion issue
– Hydrocarbons-Pressure-Temperature
– HP 3000 psi / BHT 200 / high water cuts
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
COMPRESSOR
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Gas Lift Considerations
Well Completion – 2 7/8” tubing inside 5 ½” 17# casing
Fluid rate range of 300 to 2500 BFPD Screw compressors using air allowed
operating pressures up to 1600 psi and injection volumes of 1.5 mmcf/day
Maintain velocities to produce drilling fines
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Gas Lift - First Attempts
Rig would land tubing at 2000’ Air injection through open ended tubing
and fluid produce out of casing until blown dry
Rig lowered tubing 1000’ to 1500’ and continued air injection / unloading process
Eventually air injection through tubing was at 8000’ and well clean up
Obtained good results, but at high cost
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Gas Lift Design Considerations
Determined annular lift to be best method to produce high fluid rates and drilling fines
1” IPO valves inside a slimhole SPM were used due to casing constraints
Valve ports were sized to inject up to 1.2mmcf/day
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Operation
Drilling rig runs tubing with gas lift mandrels; rig moves off location
Compressors are set on location Well is unloaded and monitored until solids
were cleaned out and a percentage of oil was seen
Workover rig is moved in to pull tubing and remove gas lift mandrels; tubing and rods are run in well for rod pump operation
Gas lift mandrels are used for next well
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Pit Gator
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Problems / Maintenance
Corrosion inhibitor plugged IPO valves Due to environment of injecting air,
equipment life was shortened Side pocket mandrels were replaced every
15 to 20 wells; valves replaced every 3 wells
Trained operator to pull and run IPO valves in side pocket mandrels; valve and latch stock is kept at field location
ARTIFICIAL LIFT SYSTEMS
®
© 2002 Weatherford. All rights reserved.
Results
Unloading process is shortened Greater rod and pump life Improved wellbore deliverability Flow back helps optimize rod pump design