ARTIFICIAL LIFT SYSTEMS ® © 2002 Weatherford. All rights reserved. Unloading Water from Oil Wells Using Air.

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