Research Project Supported by the EU “ORCHYD” Wants to Seed Up Deep Geothermal Drilling

ORCHYD, an EU-funded research, and development project involving a consortium of worldwide research partners aim to integrate two mature technologies to help enhance hard rock drilling rates.

Deep geothermal reservoirs are being looked at as a source of renewable energy all over the world. While international research efforts are rising up to the task of overcoming the low efficiency of heat recovery from depth to the surface, the conventional rotary system’s slow drilling speed in deep hard rocks (> 4 km) remains a show-stopper. Long drilling times are required for deep drilling, resulting in an unacceptably expensive initial expenditure.

ORCHYD is a research initiative directed by researchers from ARMINES/Mines-ParisTech in France, in collaboration with Imperial College London, SINTEF in Norway, the University of Piraeus in Greece, China University of Petroleum, and Drillstar in France. The Horizon 2020 program of the European Union is funding the project.

A new drilling technology will boost drilling speed thanks to EUR 4 million funding from the European Union’s Horizon 2020 program.

Hard rock drilling speeds will be increased from the existing range of 1-2 m/h to up to 4-10 m/h thanks to ORCHYD’s revolutionary drilling technology. The innovation is combining two previously distinct, mature technologies, High-Pressure Water Jetting (HPWJ) and Percussive Drilling, in a system tailored for hard rock geothermal reservoirs to depths of 6 kilometers.

The new system for field operations will be conceived, built, and validated with pilot drilling tests using planned experiments and solid-fluid coupled models designed to show the important fragmentation mechanisms under in-situ stress conditions.

The hybrid development requires optimizing: I the release of high-stress concentrations on the hole bottom while drilling; ii) the slotting of circumferential relieving grooves on the hole bottom using HPWJ (up to 200 MPa); and iii) the in-hole production of the HPWJ using a down-hole pressure intensifier activated by drilling vibrations, thus dampening out harmful drilling system vibrations and iv) a cutting-edge down-hole percussive rotating mud hammer for drilling to get the most out of the modified bottom-hole stress regime.

ORCHYD’s goal is to reduce drilling costs in hard rock areas by 65 percent. The entire cost of drilling a deep geothermal well will be reduced by 30% as a result of this. Furthermore, the novel Intensifier-HPWJ-Hammer system has the ability to dig and steer multi-lateral wells, which considerably increase thermal connectivity, are less expensive, use far less water, and are more controlled than traditional fracking stimulation.

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