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Gas-Lift Surveillance
Tools of the Trade
Jim Hall
5 February, 2002ASME/API Gas-Lift Workshop
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2002 S
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Surveillance
Close watch kept over someone or something (as by a detective)
French, from surveiller to watch over, from sur- + veiller to watch, from Latin vigilare, from vigil - watchful
Copyr
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2002 S
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Gas-Lift Well Surveillance
The process of keeping a close watch
over a gas lift well or wells.
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2002 S
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What do these items have in common?
• A lawn chair• Ice• A glass• Scotch whiskey
Copyr
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2001 S
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They are all Tools
They are tools that were regularly used by Hugh Garrett,
one of the founders of modern gas lift,
to troubleshoot a gas-lift well.
Copyr
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2002 S
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Personal Tools
•Touch Hot or cold (misleading)
Vibration
•Sound Gas or liquid ?
•Taste (!) Fresh or Salty ?
•Sight Condensation, ice
Copyr
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2002 S
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Personal Tools•Advantages
Easy starting point
No cost
No risk to well, safe for operator
•Disadvantages
Highly subjective
Rarely definitive
Difficult to document and transfer
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2002 S
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Simple Surface Tools•Gauges
Pressure
Temperature
IR remote sensors• Flow Meters
Gas
Liquid•Recorders
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2002 S
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Simple Surface Tools•Advantages
Extremely valuable information
Easily recorded and shared
•Disadvantages
Proper range
calibration and maintenance
wellsite security
sample intervals vary
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2002 S
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Complex Surface Tools
•Automation Systems
SCADA - press., temps, rates, controls
DCS - larger scale and complexity
Real-Time Lift Gas Optimisation•Remote Sensing
Video
UAV - Unmanned Aerial Vehicle
Satellite - AERA monitors subsidence
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2002 S
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Complex Surface Tools•Advantages
provide easy access to large data sets
enables remote operations
improved response to upsets
Reduction in HSE exposure of staff•Disadvantages
maintenance & calibration are critical
significant CAPEX
IT tools change constantly
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2002 S
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Simple Downhole Tools•Acoustic Well Sounder
unloading, max. unloaded depth•CO2 Tracer
injection depth / depths•Markland Pressure-Pulse
injection depth•“Whistle” Valve
injection depth
Copyr
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2002 S
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Simple Downhole Tools•Advantages
non-intrusive, low well risk
indicates possible or actual lift depth
relatively low HSE exposure•Disadvantages
Acoustic well sounder is inconclusiveCO2 Tracer in development
Pressure Pulse in development
Whistle Valve only a concept
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2002 S
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Complex Downhole Tools•Downhole Pressure & Temperature survey
mechanical, electronic, not continuous•Production Log
continuous press., temp., flow•Permanent Downhole Gauge
single point pressure and temperature•Surface-Controlled Gas-Lift Systems
tubing and wireline retrievable avail.
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2002 S
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Complex Downhole Tools•Advantages
accurate
dependable
definitive answers
surface controlled•Disadvantages
Well entry? High risk to well
No well entry? Cannot service
Increased value carries increased cost
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2002 S
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Analysis Tools•Gas Lift Slide Rule - Texaco
•Transient Simulation software
•Single-well system analysis software
•Multi well system analysis software
•Full-Field models
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2002 S
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Analysis Tools•Advantages
Improves productivity
More Science - Less Art•Disadvantages
Garbage-in Garbage-out
slide-rule intuition has been lost
Analysis Paralysis
Must calibrate and maintain models
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2002 S
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No Substitue for Experience!
A tool in the hands of an inexperienced user often does more harm than good.
By 2008 - 60% of E&P company expertise will retire or move out of the industry
Our challenge is not only to develop the tools, but to put them in the hands of staff who can use them to the fullest.
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