NEXT-Drill: Numerical-EXperimental Technology platforms for cost effective deep hard rock Drilling

The project has been running in agreement with the plan. The WP1 has established a report on 'Hard rock drilling roadmap'. Four Workshops (yearly event planned in WP1) on 'Hard Rock Drilling geothermal' have been organized at Stavanger in during the project. The 'roadmap' report updated to include feedback received at the last workshop is under quality assurance revision and will be made available in February 2016. WP2/3 activities have followed the strategy to account for both the 'tool life' and the 'Rate of Penetration (ROP)' for drilling efficiency. - Various drill bit insert grades used with percussive hammer where investigated. Specimens were manufactured by the partners HC-Starck and Sandvik and tested at laboratory by sintef during 2014/2015. Drillbits (10 drillbits for each grade) were also produced and field tests performed for all material grades by LKAB-Wassara in Malmberget. Results shown that an optimal drillbit material for deep hard rock should minimise the sources of material heterogeneities that can promote damage of tool in operating conditions. The reduction of (cemented carbide) grain size distribution contributes to this minimisation, this is confirmed by an increase of wear resistance in field conditions. - Dynamic and static confining rock tests were performed (100 tests) by NTNU and in collaboration with TUT (Tampere University of Technology) at University of Purdue in Mars 2015. A paper has been accepted in December 2015 at Int. J of Impact Engineering: 'Effects of strain rate and confining pressure on the compressive behavior of Kuru Granite'. Results suggest potential ROP improvement by combining impact and shear loading in deep drilling conditions, taking advantage of the change of rock fracture mechanisms with depth. Also middle scale tests for ROP efficiency performed at Resonator and Sintef shown a significant ROP improvement (20% under idealized air flushing conditions) by controlling the RPM (rotation speed). The influence of hammer frequency could not be extracted from middle scale hammer tests. Marion Fourmeau (MF) has finished in October 2015 her PostDoc and is now working as researcher at SintefMC. Based on the collaboration with Professor E. Detournay (from Minneapolis) on the development of a drill bit rock interface law, a paper has been published in June 2015 at the American Rock Mechanics Association (ARMA). A second paper at Int. J of Impact Engineering on 'an Experimental and Numerical study of drillbit impact on Kuru Granite' has been submitted in Juanary 2016. From February to August 2015 MF has also supervised 1 Master student (Ombline de la Tour) to enrich a rock model by localization analysis to better capture the shipping process during percussive impact. Dmitri Tkalich (DT) PhD candidate has submitted 2 Int. journal papers (based on triaxial tests performed in 2014/2015 to account for the pressure influence in deep drilling and based on multiscale simulations of drillbit insert tool material response). DT is now finishing 2 other papers and has scheduled his PhD Defense to fall 2016. 4 Technical committee and 2 Steering Committee meetings have been organized each year. Beside regular (monthly) status were sent to all partners on activities/milestones/budgets. Partners have provided consequent in-kind contribution during the project such as tool material, testing facilities and workshop organization. The project ambition is also to support geothermal activities and relevant initiatives: - An Initiatives for a KPN project 'INNODrill' expected to start in Q1 2016 and defined as extension of NextDrill, to address multiphysics phenomena influencing the tool/rock interaction and the resulting drilling performance (including technology demonstration and trials in deep geo-thermal fields). - SINTEF submitted a sketch for an FME (RENEW-Drill) in spring 2015 and have been in dialogue to integrate this with an FME initiative instigated from UiB and submitted in November 2015. - An application for a Nordic Center of Excellence (NCoE) For Responsible Arctic Resource Development (2015-2020) has been submitted with thematic relevance for NextDrill. - NextDrill has anchored the project to EERA Joint Program on Geothermal Energy, It will further be considered to anchor INNO-Drill and EERA JPGE, if sanctioned by the steering committee.

The main objective of the present project is to develop a technology- and knowledge platform for the design of new and significantly more cost effective drilling tools and systems for deep geothermal wells in hard rock formations. The four research partn ers SINTEF, IRIS, NTNU and UiS behind the present application have formed an expert group for geothermal drilling and development ('EGBU'). The following second objectives have been defined as outcome of the proposal: -To survey and integrate basic R&D an d industrial technologies for the identification of technology roadmaps and infrastructure. - To establish test methods for characterization of the fundamental mechanisms of hard rock fracturing induced by dynamic bit?rock interactions. -To establish an experimentally validated numerical model for rock fracturing and tool/rock interaction studies, and to make it available for industrial exploitation. The project will allow gathering several gründer/technology companies in a joint venture to develop a te chnology platform of mutual importance. One PhD student and several MSc-students will be educated as part of the project will be involved in to strengthen the collaboration between the Norwegian players (research and corporate partners) and their link to international 'clusters' in France, Germany and Sweden.