Copyright 2001 SIEP B.V. Gas-Lift Surveillance Tools of the Trade Jim Hall 5 February, 2002 ASME/API Gas-Lift Workshop

Copyright 2002 SIEP B.V. 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

Copyright 2002 SIEP B.V. Gas-Lift Well Surveillance The process of keeping a close watch over a gas lift well or wells.

Copyright 2002 SIEP B.V. What do these items have in common? A lawn chair Ice A glass Scotch whiskey

Copyright 2001 SIEP B.V. 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.

Copyright 2002 SIEP B.V. Personal Tools TouchHot or cold (misleading) Vibration SoundGas or liquid ? Taste (!)Fresh or Salty ? SightCondensation, ice

Copyright 2002 SIEP B.V. 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

Copyright 2002 SIEP B.V. Simple Surface Tools Gauges Pressure Temperature IR remote sensors Flow Meters Gas Liquid Recorders

Copyright 2002 SIEP B.V. Simple Surface Tools Advantages Extremely valuable information Easily recorded and shared Disadvantages Proper range calibration and maintenance wellsite security sample intervals vary

Copyright 2002 SIEP B.V. 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

Copyright 2002 SIEP B.V. 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

Copyright 2002 SIEP B.V. Simple Downhole Tools Acoustic Well Sounder unloading, max. unloaded depth CO 2 Tracer injection depth / depths Markland Pressure-Pulse injection depth “Whistle” Valve injection depth

Copyright 2002 SIEP B.V. Simple Downhole Tools Advantages non-intrusive, low well risk indicates possible or actual lift depth relatively low HSE exposure Disadvantages Acoustic well sounder is inconclusive CO 2 Tracer in development Pressure Pulse in development Whistle Valve only a concept

Copyright 2002 SIEP B.V. 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.

Copyright 2002 SIEP B.V. 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

Copyright 2002 SIEP B.V. Analysis Tools Gas Lift Slide Rule - Texaco Transient Simulation software Single-well system analysis software Multi well system analysis software Full-Field models

Copyright 2002 SIEP B.V. 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

Copyright 2002 SIEP B.V. No Substitue for Experience! A tool in the hands of an inexperienced user often does more harm than good. By % 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.