Periodic Reporting for period 2 - ORCHYD (Novel Drilling Technology Combining Hydro-Jet and Percussion for ROP Improvement in deep geothermal drilling)
Reporting period: 2022-07-01 to 2024-09-30
Geothermal energy harnesses the heat of underground rocks to convert water to steam and supply an uninterrupted power as opposed to wind and solar energy sources. This makes geothermal energy a leading candidate for carbon neutral, efficient, non-intermittent and reliable source of renewable energy supply across the globe. However, the current drilling methods to reach the rocks at a depth of more than 4 km are slow and inefficient – making geothermal sources supply less than 2% to the global energy share.
The ORCHYD project aims to increase the unit drilling rate (measured in rate of penetration, ROP) by four times the average rate currently possible – drastically reducing the drilling costs by up to 65%. This first-of-its-kind drilling approach, combining two established rock cutting technologies - High Pressure Water Jet (HPWJ) for rock cutting (up to 250 MPa) and percussive drilling using down-the-hole (DTH) hammer - will make the utilization of geothermal energy cheaper and more widely available, facilitating the energy transition to tackle the global climate crisis.
The overall objective of the ORCHYD project is to develop a non-conventional and fully fluid driven drilling process combining the following systems to achieve the envisioned 4X increase in ROP:
- HPWJ system to be able to slot circumferential grooves of desired depth in the bottom-hole conditions.
- In-hole production of the HPWJ using pressure intensifier(s).
- High power advanced mud driven DTH hammer.
- Diamond-enhanced-insert hammer bit.
In conclusion, a prototype combining the DTH hammer and an intensifier was developed and tested in the laboratory environment under representative drilling conditions. The optimized drilling bit profile and jetting configuration for improved rock breaking efficiency through impact and HPWJ has improved the drilling rate by at least 4 times while tested using hard crystalline granites like Sidobre. The project demonstrated that the developed technology has its potential in improving the drilling rate in geothermal wells and thus result in significant cost reduction in its development to scale geothermal as a viable energy source.
The ORCHYD project aims to increase the unit drilling rate (measured in rate of penetration, ROP) by four times the average rate currently possible – drastically reducing the drilling costs by up to 65%. This first-of-its-kind drilling approach, combining two established rock cutting technologies - High Pressure Water Jet (HPWJ) for rock cutting (up to 250 MPa) and percussive drilling using down-the-hole (DTH) hammer - will make the utilization of geothermal energy cheaper and more widely available, facilitating the energy transition to tackle the global climate crisis.
The overall objective of the ORCHYD project is to develop a non-conventional and fully fluid driven drilling process combining the following systems to achieve the envisioned 4X increase in ROP:
- HPWJ system to be able to slot circumferential grooves of desired depth in the bottom-hole conditions.
- In-hole production of the HPWJ using pressure intensifier(s).
- High power advanced mud driven DTH hammer.
- Diamond-enhanced-insert hammer bit.
In conclusion, a prototype combining the DTH hammer and an intensifier was developed and tested in the laboratory environment under representative drilling conditions. The optimized drilling bit profile and jetting configuration for improved rock breaking efficiency through impact and HPWJ has improved the drilling rate by at least 4 times while tested using hard crystalline granites like Sidobre. The project demonstrated that the developed technology has its potential in improving the drilling rate in geothermal wells and thus result in significant cost reduction in its development to scale geothermal as a viable energy source.
A significant drop in ROP in deep geothermal drilling is caused by increasing geostatic and overburden stresses with depth. One solution is slotting a peripheral groove ahead of the drill face, which numerical simulations show reduces mean stress near the drill bit, promoting rock failure. A full-scale hybrid system combining HPWJ and a DTH hammer was developed and tested, demonstrating at least 2.5x higher ROP in hard granites compared to a DTH hammer without HPWJ.
Numerical studies optimized groove depth for various drill bit shapes and demonstrated efficient grooving using HPWJ pressures up to 250 MPa. The simulations also predicted impinging pressure distribution based on jet nozzle parameters, enabling determination of the maximum stand-off distance for effective DTH hammer assistance. A feasibility study explored producing the required in-hole high pressure using a downhole pressure intensifier. Parallel studies examined hydraulic (HPWJ) and mechanical (percussion) rock-breaking methods. Simulations showed how drill bit profiles influence rock fracturing modes (tensile vs. shear) at groove bottoms. Rock microstructure models further linked fracturing efficiency to bottom-hole conditions. A characterization study confirmed that environmentally friendly drilling fluid additives could reduce friction by up to 70% while improving viscosity. Environmental evaluations, including Life Cycle Analysis, noise risk assessments, and ecological footprint studies, highlighted ORCHYD’s favorable environmental impact and contribution to sustainable geothermal drilling.
Experimental validation confirmed that optimized prototypes combining HPWJ and DTH hammer technology achieved more than 4x higher ROP than conventional rotary systems. The hybrid system successfully drilled hard crystalline rocks like Sidobre under lab conditions. The project culminated in over 30 publications, presentations at international conferences, and participation in industry trade shows and European-level discussions, solidifying ORCHYD's role in advancing geothermal drilling technologies.
Numerical studies optimized groove depth for various drill bit shapes and demonstrated efficient grooving using HPWJ pressures up to 250 MPa. The simulations also predicted impinging pressure distribution based on jet nozzle parameters, enabling determination of the maximum stand-off distance for effective DTH hammer assistance. A feasibility study explored producing the required in-hole high pressure using a downhole pressure intensifier. Parallel studies examined hydraulic (HPWJ) and mechanical (percussion) rock-breaking methods. Simulations showed how drill bit profiles influence rock fracturing modes (tensile vs. shear) at groove bottoms. Rock microstructure models further linked fracturing efficiency to bottom-hole conditions. A characterization study confirmed that environmentally friendly drilling fluid additives could reduce friction by up to 70% while improving viscosity. Environmental evaluations, including Life Cycle Analysis, noise risk assessments, and ecological footprint studies, highlighted ORCHYD’s favorable environmental impact and contribution to sustainable geothermal drilling.
Experimental validation confirmed that optimized prototypes combining HPWJ and DTH hammer technology achieved more than 4x higher ROP than conventional rotary systems. The hybrid system successfully drilled hard crystalline rocks like Sidobre under lab conditions. The project culminated in over 30 publications, presentations at international conferences, and participation in industry trade shows and European-level discussions, solidifying ORCHYD's role in advancing geothermal drilling technologies.
The state of stress regimes in highly stressed deep rocks and the stress release process, crucial for improving ROP in deep geothermal drilling, remain largely unexplored. Recent progress has advanced several aspects related to this challenge. In rock destruction using HPWJ, innovative numerical modeling techniques have extended adaptive mesh Computational Fluid Dynamics (CFD) to address concentrated impinging pressure at extremely high Reynolds numbers in rotating jet scenarios. These models, validated against laboratory jetting tests under high confining and back pressures, generate detailed surface pressure inputs for solid deformation models, revealing the depths and rock types where stress-relieving grooves of desired depth can be achieved.
For percussive rock destruction, the ORCHYD project introduced a multiscale modeling framework to optimize bottomhole configurations (bit shape, insert position, groove depth, WOB, impact energy, etc.). Discrete and continuum approaches complement each other to model the bit-rock interface, linking the HPWJ system dynamics with rock fracturing models. An extended mechanical behavior database supports calibration and validation, while studies on enhanced drilling fluids indicate potential for environmentally friendly additives to improve tool life and particle transport. Future studies will assess the environmental impact of ORCHYD technology on global energy security.
Initial results demonstrated a 100% improvement in ROP under moderate rock confining conditions, and further optimization in the second period of the project, the ORCHYD prototype increased drilling rates fourfold in hard crystalline granites like Sidobre compared to conventional rotary systems. Anticipated operational savings could reduce hard rock section drilling costs by up to 65%, significantly impacting investments in deep geothermal projects. The combined HPWJ and DTH hammer process shows promise for applications in mining, energy storage, CO2 storage, environmental monitoring, and remediation, with numerical tools and experimental devices enabling tailored optimization for specific systems.
For percussive rock destruction, the ORCHYD project introduced a multiscale modeling framework to optimize bottomhole configurations (bit shape, insert position, groove depth, WOB, impact energy, etc.). Discrete and continuum approaches complement each other to model the bit-rock interface, linking the HPWJ system dynamics with rock fracturing models. An extended mechanical behavior database supports calibration and validation, while studies on enhanced drilling fluids indicate potential for environmentally friendly additives to improve tool life and particle transport. Future studies will assess the environmental impact of ORCHYD technology on global energy security.
Initial results demonstrated a 100% improvement in ROP under moderate rock confining conditions, and further optimization in the second period of the project, the ORCHYD prototype increased drilling rates fourfold in hard crystalline granites like Sidobre compared to conventional rotary systems. Anticipated operational savings could reduce hard rock section drilling costs by up to 65%, significantly impacting investments in deep geothermal projects. The combined HPWJ and DTH hammer process shows promise for applications in mining, energy storage, CO2 storage, environmental monitoring, and remediation, with numerical tools and experimental devices enabling tailored optimization for specific systems.