#drill_rig__drillrig__drilling_rig__oilrig__oil_rig  rig used in drilling for oil or gas
  supertype:  #rig  gear (including necessary machinery) for a particular enterprise
  subtype:  #drilling_platform__offshore_rig  drilling rig consisting of an offshore platform (floating or fixed to the sea bed) from which many oil wells can be bored radially

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