6 gas lift troubleshooting (4)
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Gas Lift Troubleshooting
Gas Lift Troubleshooting
GAS LIFT TROUBLESHOOTING
IS A PROCESS !!
NOT A PROJECT !!
GAS LIFT TROUBLESHOOTING
CONSISTS OF
1. DATA GATHERING
2. ANALYSIS
3. IMPLEMENTATION
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
PREVENTATIVE MAINTENANCE
UNLOADING THE GAS LIFTINSTALLATION
IS THE MOST CRITICAL TIME IN THE LIFE OF AN ISTALLATION
CAN DESTROY THE SEATS PREVENTING UPPER VALVE CLOSURE
GL Well Unloading Sequence
G. L. Well Unloading Sequence Part 2
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
HIGH FEED-IN WELLS
Are the most difficult to prevent valve damage
High feed-in wells also take on fluids at high rates
Most of the fluids will go into formation during unloading
High rates of fluid flow going through the valves
Can cut out valves quickly
1 2 3 4 5 6 7 8 9 10 11 12 13
S1S2
0
200
400
600
800
1000
1200
Inje
ctio
n G
as V
olu
me,
MC
F/D
Time, 100 Minutes
Gas Lift Unloading Schedule
API C Value
Inj Gas Volume
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
S1
0
100
200
300
400
500
600
700
800
900
1000
Series1Series2
GAS LIFT WELL UNLOADING SEQUENCE
ELAPSED TIME, 100 MINUTES
INJECTION GAS VOL
API "C" VALUE = 900
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
SURFACE CHOKES
A WELL SHOULD NOT BE UNLOADED AGAINST A SURFACE CHOKE UNLESS THE WELL IS EXPECTED TO COME IN FLOWING
IN CASE OF SAND PRODUCTION, CONTROL THE PRODUCTION RATE WITH INPUT GAS NOT A CHOKE
CHOKES REDUCES PRODUCTION RATE
CHOKES CAUSE EXCESSIVE GAS USAGE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
DIAGNOSTICS
Optimizing Production
• Increase injection 50 to 100 mcf per day• Give well time to stabilize 24 hrs is
recommended.• If production rate increases continue
increasing until rate drops.• Low injection rate back to last rate.
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
•GAS LIFT PROBLEMS ARE INDICATED BY:
•HEADING
•TAKING INSUFFICIENT INJECTION VOLUMES•TAKING EXCESSIVE INJECTION VOLUMES
•LOSS OF PRODUCTION RATE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
Areas where problems can exist:
INLET
OUTLET
SUB-SURFACE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
GAS LIFT WELL’S ARE SUBJECT TO BUT NOTLIMITED TO THE FOLLOWING OPERATINGPROBLEMS:INLET:
EXCESSIVE INJECTION GAS VOLUMES
Injection choke sized too large - Injection pressure at or above max
operating pressure - Causes re-opening of upper valves - Reduction in production rate
Gas Lift Performance Curve
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
Most gaslift design programs are static.They assume the annulus pressure changes as eachlower valve is uncovered. This will happen only ifthe injection rate is matched to the flow rate throughthe valve. In most cases, the annulus pressurechanges continuously during the unloading phase.
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
I
LOW INJECTION GAS VOLUMES
INJECTION GAS CHOKE SIZED TOO SMALL
- Heading
- Reduction in production rate
- Can prevent well from unloading
Freezing or plugged injection choke
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
HIGH INJECTION PRESSURE WITH LOW INJECTION VOLUME:
-OPERATING VALVE MAY BE PARTIALLY PLUGGED
-HIGH TUBING PRESSURE REDUCING THE DIFFERENTIAL
AT THE OPERATING VALVE
-INDICATION OF TEMPERATURE EFFECT
-CAN KEEP WELL FROM WORKING TO DEEPER GLV’S
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
LOW INJECTION PRESSURE
- VALVE PRESSURES SET TOO LOW
- PLUGGED SURFACE VALVES
- FREEZING
- GAS DISTRIBUTION LINES MAY BE TOO SMALL
ACCURACY OF GAUGES AND SURFACE MEASURINGEQUIPMENT
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
OUTLET PROBLEMS
HIGH BACK PRESSURE
- CHOKES OR CHOKE BODIES
- LONG OR UNDERSIZED FLOW LINES
- BUILDUP OF SALT, PARAFFIN, SCALE
- HILLY TERRAIN
- HIGH SEPARATOR PRESSURE
CAN CAUSE: OPERATION FROM UPPER VALVES
EXCESSIVE GAS USAGE
REDUCED PRODUCTION
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
DOWNHOLE PROBLEMS
WELL HEADING
- GAS LIFT VALVE PORTS SIZED TOO LARGE
- ORIFICE VALVE NOT SIZED PROPERLY
- LOW INJECTION GAS RATE
- TEMPERATURE INTERFERENCE
- TUBING SIZED TOO LARGE
- LIMITED FEED-IN FROM THE FORMATION
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
WELL NOT TAKING INJECTION GAS
- FREEZING OR PLUGGED INJECTION VALVE
- TEMPERATURE PROBLEMS
- GAS LIFT VALVE SET PRESSURES TOO HIGH
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
INSTALLATION STYMIED AND WILL NOT UNLOAD
- HEAVIER FLUID GRADIENT THAN ANTICIPATED
- VALVE PRESSURES SET TOO HIGH
- VALVE SPACING IS TOO WIDE
- TEMPERATURES ARE INCORRECT
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
WELL CIRCULATING DRY GAS
- OPENING UPPER GLV’S
- HOLE IN THE TUBING
- ORIFICE VALVE WITH NO FEED-IN
- HANGER OR PACKER LEAK
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
VALVE HUNG OPEN
- INJECTION PRESSURE BLEEDS DOWN BELOW THE
CLOSING PRESSURE OF THE GLV’S
- COULD BE TRASH OR SALT BUILDUP
- CUT OUT SEAT FROM IMPROPER UNLOADING
- BELLOWS FAILURE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
HOLE IN THE TUBING
- LOW INJECTION PRESSURE
- EXCESSIVE GAS USAGE
- REDUCED PRODUCTION RATE
- HEADING
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TroubleshootingDiagnostic Tools
Wireline-tagging fluid/check perfs for fillEchometerWell Tests-performed properlyInjection Gas Measurement- in and outTwo or Three Pen Charts- every wellPressure/Temperature Surveys- performed properly
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
PRIORTIZE CANDIDATES
FLOWING SURVEYS ARE MOST ACCURATE
FLOWING SURVEYS ARE ALSO MOST COSTLY
PRIORTIZE CANDIDATES BY THE LEAST EXPENSIVE METHODS FIRST
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TAGGING FLUID - WIRELINE UNIT
PROBLEMS THAT CAN BE INDENTIFIED:
PLUGGED OR OBSTRUCTRED TUBING
PARAFFIN, SCALE OR OTHER DEPOSITS
FILL-IN OVER THE PERFORATIONS
ABNORMALLY LOW FLUID LEVELS
ABNORMALLY HIGH FLUID LEVELS
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TAGGING FLUID - WIRELINE UNIT
LIMITATIONSCAN GIVE INCORRECT ESTIMATION OF OPERATING VALVE
-FEED-IN WILL OFTEN RAISE FLUID LEVEL
-FLUID FALLBACK WILL ALWAYS OCCUR-BOTH WILL GIVE WRONG ESTIMATION OF OPERATING VALVE
INPUT GAS SHOULD BE CLOSED PRIOR TO CLOSING THE WING VALVE (WILL DRIVE THE FLUID LEVEL DOWN)
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TUBING - CASING COMMUNICATION-ONE OF THE MOST COMMON GAS LIFT PROBLEMS
-OFTEN GOES UNDETECTED
-DIFFICULT TO PROVE
TO PROVE COMMUNICATION EXISTS-SHUT IN WELL WITH WING VALVE
-LEAVE INJECTION GAS ON UNTIL WELL EQUALIZES
-BLEED CASING DOWN AS FAST AS POSSIBLE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TUBING -CASING COMMUNICATION
IF TUBING PRESSURE FALLS AT ALL, THERE ISCOMMUNICATION
IF THE TUBING PRESSURE DOES NOT FALL,COMMUNICATION WAS NOT PROVEN BUTSTILL MIGHT EXIST
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TUBING -CASING COMMUNICATION
OTHER PROCEDURES:
EQUALIZE-
BLEED CASING DOWN-
SHOOT ECHOMETER.
If casing fluid level rises, there is communication
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
TUBING-CASING COMMUNICATION
OTHER PROCEDURES:
SET TUBING PLUG
FILL TUBING WITH WATER AND PRESSURE UP
IF COMMUNICATION THEN THE CASING PRESSURE WILL RISE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
MEASUREMENT OF GAS VOULMES - IN AND OUT
l DETERMINE EFFICIENCY OF INJECTION GAS
l DETECT ADDITONAL GAS CONSUMPTION RIGHT AWAY
l OUTPUT HELPS DETERMINE FGOR
l HELPS DETECT HOLES IN THE CASING
l SET UP SO EACH WELL CAN BE TESTED
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
WELL TESTS
l DETECT CHANGES IN PRODUCTION EARLY
l DETECT WATER CUT INCREASES
l SHOULD BE OF LENGTH OF TIME TO BEMEANINGFUL
l OFTEN ENOUGH TO CATCH PROBLEMS EARLY
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
WELL TEST PREPARATIONSTABILIZATIONTO ENSURE THAT THE DATA IS REPRESENTATIVE OF
ACTUAL WELL PERFORMANCE:
INDICATIONS
l CONSTANT WELLHEAD PRESSURE
l CONSTANT GAS-PRODUCTION RATE
l CONSTANT FLUID PRODUCTION RATE
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
WELL TEST PREPARATION
EQUIPMENT CHECKNEED PROPERLY MAINTAINED EQUIPMENT TO RESULT IN
ACCURATE WELL TESTS………CHECK
l FOR LEAKAGE
l OPERATION OF ALL CONTROL VALVES
l TO BE SURE WELL FLUID IS PROPERLY ISOLATED
l CALIBRATION OF FLUID AND GAS METERS
l ALL PRESSURE GAUGES
l THAT ORIFICE PLATE IS CLEAN, FLAT AND FREE OF NICKS
© Weatherford. All rights reserved.
ARTIFICIAL LIFT SYSTEMS
®
Gas Lift Diagnostics
Gas Lift Well Flowing Survey
TROUBLESHOOTING
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