Downhole Monitoring

◊ This webpage ist intended to summarize the current state of the art in Permanent Down-hole Monitoring (PDM) both in the service industry as well as the academia and provides an outlook and recommendation for future development and research. It further proposes suggestions and decision aids for Principle Investigators and scientists referring their selection criteria for an array system on the basis of reliability, sensitivity, risk of failure and investment cost.  At a later stage this support will be available on-line via this portal. The systems suitable for PDM can be categorized in 2 types of installations:

1. Outside the casing, facing the rock formation and permanently cemented in place, and
2. Inside casing or open hole by means of wire-line or pipe deployed with a retrieval option.

◊ Common to both types is the extended requirement to down-hole life expectancy as a minimum system reliability of  5 years mean-time between failure (MTBF) as well as measurement repeatability over periods of 10-15 years and array design criteria with special emphasis on redundancy of sensors and telemetry lines in order to mitigate the risk for premature failure.
In an attempt to cover the majority of the PDM applications in scientific well drillings, an environmental regime of 125°C at 500 bar for +20.000 hours continuous operation is targetted for components survival.

Contact: Bernhard Prevedel

CONTENT of this Portal are ICDP collected reports, data and recommendation for:

• Purpose and definitions of PDM applications
  
• Deployment systems for PDM arrays
  
  • Line
    
    • Wire rope with multi-lead PU cable clamped to the side
    • Armoured electric or FO augmented cable
  • Coil Tubing
    
    • Steel tubing with inner armoured wireline
    • Composite coil tubing with integrated wires/lines
  • Pipe
    • Casing, Tubing or Drill Pipe
      
• Hole-anchoring systems
  
  • Retrievable and multiple settable devices
    
    • Mechanical, hydraulic and free-suspended on cable or pipe
  • Permanent anchors
    • outside the casing cemented or bottom hole cemented
      
• Measurements and sensors available in academia and industry
  
  • Geophysical
  • Geometrical
  • Geomechanical
  • Environmental
  • Geochemical
    
• Data Recording and data management solutions
  
  • Down-hole memory
    
    • mechanical recording
    • electric memory
  • Real-time surface telemetry
    
• Operations risk management prodecures and mitigation strategies 
  • Type of  failures and probabilities
  • Redundancy concepts
  • Failure risk management tools
  • Mitigation strategies<
    
• State of the art incl. new developments in PDM technology
  
  • Industry available
  • Academia available
    
• ICDP projects and their scientific requirements for PDM

• Array design principles and recommendations for ICDP applications

• Economics: Investment and repair/maintenance cost

• Alternative PDM methods and solutions

• Outlook and needs for continued research

• Tables, graphs