Geothermal Well Drilling

Challenge

Three major problems are commonly encountered whilst drilling Geothermal wells:

  • Poor to very poor rate of penetration (ROP) is achieved with the typically hard formations such as basement rock and volcanics routinely impeding progress
  • High bit wear rates lead to regular tripping to replace the dulled bits leading to high levels of associated non-productive time (NPT)
  • Stuck-pipe arising from loss or circulation and resulting differential sticking at highly fractured intervals

Risk

Risks to successfully achieving TD within the AFE are:

  • High wear rate on bits causing NPT through regular tripping to replace dulled bits, particularly time consuming and costly in ultra-deep wells
  • High replacement cost of dulled bits
  • Poor to very poor ROP through hard formations leading to excessive time
  • Stuck pipe and inability to free stuck pipe due to ineffectiveness of conventional jars in high temperature geothermal wells
  • Loss of hole section and need to abandon BHA and side-track

Solution

Three hugely differentiated technologies are available to geothermal drilling operators and engineers:

  1. Inclusion of GeoVolve HAMMER in the BHA directly behind the bit provides and all-metal, drilling fluid powered, plug and play, percussive drilling action which:
    • Enables huge ROP gains in hard rock
    • Extends bit life in hard rock
    • Improves weight transfer to the bit
    • Introduces a minimal pressure drop
    • Has no elastomeric seals and is suitable for Ultra-HP/HT environments
    • Reduces WOB requirement
    • Is a simple plug-and-play installation
    • Is simply operated by drilling fluids and is compatible with any mud/fluid
    • Features autonomous, automatic operation
    • Has a simple robust construction
    • Reduces stick-slip dynamic
    • Reduces high frequency vibration
    • Maintains bit contact
    • Requires no specialist personnel
    • Is full bore
  2. Inclusion of the HydroVolve HAMMER in the drill string significantly increases the likelihood of recovering from stuck-pipe incidents in Geothermal drilling due to its:
    • instant, rapid and continuous vibro-impacting extraction action
    • rotational decoupling of the drillstring from the stuck pipe breaking the static friction of the string in the hole providing much improved load transfer
    • open circulation path to annulus and aiding hole cleaning and fluid management
    • shorter, lighter BHAs with less contact area
    • HP/HT all-metal valving mechanism
  3. Placement of MonoVolve REDUCER’s across build sections will significantly reduce the torque and drag, enhancing drillstring and BHA resilience, saving casing wear and increasing drilling performance and ROP and importantly, if called into action, HydroVolve HAMMER performance.