6 Gas Lift Troubleshooting (4)

Gas Lift Troubleshooting

GAS LIFT TROUBLESHOOTING

IS A PROCESS !! NOT A PROJECT !!

GAS LIFT TROUBLESHOOTING CONSISTS OF

1. DATA GATHERING 2. ANALYSIS 3. IMPLEMENTATION

PREVENTATIVE MAINTENANCE ®

UNLOADING THE GAS LIFT INSTALLATION IS THE MOST CRITICAL TIME IN THE LIFE OF AN ISTALLATION CAN DESTROY THE SEATS PREVENTING UPPER VALVE CLOSURE ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

GL Well Unloading Sequence

G. L. Well Unloading Sequence Part 2

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Unloading Schedule

Injection Gas Volume, MCF/D

1200

1000

800

API C Value 600

400

200

Inj Gas Volume

0 1

2

3

4

5

6

7

Time, 100 Minutes

8

9

10

S2 S1 11

12

13

GAS LIFT WELL UNLOADING SEQUENCE

1000 I N J E C T I O N G A S V O L

900

API "C" VALUE = 900

800 700 600 500 400

Series1 Series2

300 200 100 0 1

2

3

4

5

6

7

8

9

10

11

12 13 ELAPSED TIME, 100 MINUTES

14

15

16

17

S1 18

19

20

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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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. ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

•GAS LIFT PROBLEMS ARE INDICATED BY: •HEADING •TAKING INSUFFICIENT INJECTION VOLUMES •TAKING EXCESSIVE INJECTION VOLUMES •LOSS OF PRODUCTION RATE

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

Areas where problems can exist: INLET OUTLET SUB-SURFACE

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

GAS LIFT WELL’S ARE SUBJECT TO BUT NOT LIMITED TO THE FOLLOWING OPERATING PROBLEMS: 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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Performance Curve

Gas Lift Diagnostics ®

Most gaslift design programs are static. They assume the annulus pressure changes as each lower valve is uncovered. This will happen only if the injection rate is matched to the flow rate through the valve. In most cases, the annulus pressure changes continuously during the unloading phase.

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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 MEASURING EQUIPMENT

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

WELL NOT TAKING INJECTION GAS - FREEZING OR PLUGGED INJECTION VALVE - TEMPERATURE PROBLEMS - GAS LIFT VALVE SET PRESSURES TOO HIGH

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

HOLE IN THE TUBING - LOW INJECTION PRESSURE - EXCESSIVE GAS USAGE - REDUCED PRODUCTION RATE - HEADING

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

Troubleshooting Diagnostic Tools Wireline-tagging fluid/check perfs for fill Echometer Well Tests-performed properly Injection Gas Measurement- in and out Two or Three Pen Charts- every well Pressure/Temperature Surveys- performed properly ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

PRIORTIZE CANDIDATES FLOWING SURVEYS ARE MOST ACCURATE FLOWING SURVEYS ARE ALSO MOST COSTLY PRIORTIZE CANDIDATES BY THE LEAST EXPENSIVE METHODS FIRST

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

TAGGING FLUID - WIRELINE UNIT LIMITATIONS CAN 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) ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

TUBING -CASING COMMUNICATION IF TUBING PRESSURE FALLS AT ALL, THERE IS COMMUNICATION IF THE TUBING PRESSURE DOES NOT FALL, COMMUNICATION WAS NOT PROVEN BUT STILL MIGHT EXIST

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

TUBING -CASING COMMUNICATION OTHER PROCEDURES: EQUALIZEBLEED CASING DOWNSHOOT ECHOMETER. If casing fluid level rises, there is communication

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

WELL TESTS l

DETECT CHANGES IN PRODUCTION EARLY

l

DETECT WATER CUT INCREASES

l

SHOULD BE OF LENGTH OF TIME TO BE MEANINGFUL

l

OFTEN ENOUGH TO CATCH PROBLEMS EARLY

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

WELL TEST PREPARATION STABILIZATION TO 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

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

WELL TEST PREPARATION EQUIPMENT CHECK NEED 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 ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Diagnostics ®

ARTIFICIAL LIFT SYSTEMS © Weatherford. All rights reserved.

Gas Lift Well Flowing Survey

TROUBLESHOOTING