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The Natural Energy Laboratory of Hawaii Authority (NELHA) conducts experiments in Ocean Thermal Energy Conversion (OTEC). NELHA required a conduit for power and telemetry cable to operate a neutrino telescope for the DUMAND (Deep Underwater Muon and Neutrino Detector) Project that was being constructed 20 miles offshore and 15,000 feet below sea level in Keahole Point, Hawaii.
The purpose of this project was to drill a shaft, starting on shore, toward the ocean passing beneath the shoreline and then curving upward to penetrate the seafloor at an offshore depth where the cables would be free from the destruction of storm-driven waves and currents.
Geological complications were generated when lava flow entered the ocean, forming pillow lava and exploding in glassy fragments that formed "black sand" beaches. The strength of the rock can be highly variable and sometimes changed in a matter of inches.
The lava is extremely abrasive with unconfined compressive strengths in excess of 11,000 psi. In addition, because of the fractured nature of the lava, there was no circulation of the drilling fluids.
The waters off Keahole Point are of extraordinary clarity, with visibility in excess of one hundred feet. Because this project was impacting Class AA offshore waters, conventional drilling fluids or seaward discharge of cuttings were not allowed.
Directional drilling with the Accu-dril™ Motor greatly reduced the impact to the sensitive coral reef as opposed to conventional blasting and trenching techniques, which are devastating to the pristine marine environment. Accu-Dril™ Motors met the challenge of drilling in the unpredictable volcanic terrain encountered in Hawaii. Field tested and proven, Accu-dril™ motors were dependable in these adverse drilling conditions