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ThermoDrill Report Summary

Project ID: 641202

Periodic Reporting for period 1 - ThermoDrill (Fast track innovative drilling system for deep geothermal challenges in Europe)

Reporting period: 2015-09-01 to 2017-02-28

Summary of the context and overall objectives of the project

ThermoDrill is a European research project heading for an affordable drilling system for deep geothermal wells. The rig time contributes around 60% to the total costs of a geothermal energy plant and consequently provides high risk to potential investors. Reducing the rig time by increasing the drilling speed is the major goal of this project.
Hard rocks occurring with increasing depth are adding to the complexity that has to be dealt with. By combining two proven technologies into one innovative system, namely water jetting and rotary drilling, an increase of the rate of penetration by at least 100% should be achievable. As a consequence of the increased efficiency and reduced rig time, a minimum cost saving of 30% is anticipated.
This is very important for society as there is an urgent need for base-load energy provision along.
The consortium consists of nine partners, operators from the energy sector, manufacturers and service providers as well as universities.
ThermoDrill started in September 2015 and is projected for three years. After proving the feasibility and establishing the new drilling concept, the project is now successfully entering into the construction and testing phase.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

18 months into the ThermoDrill project, the complexity of the challenge to design a completely new drilling system for hard rock penetration in deep geothermal wells has been revealed.
Hundreds of tests, months of research and investigations, numerous workshops, teleconferences, meetings, and designs later, the results are very satisfactory. Based very hard granite specimen, the consortium was able to prove under confined pressures as can be expected in boreholes at 3000 meters, that the initial idea is feasible, in fact outperformed the most optimistic expectations.
Jetting tests within the specially designed pressure vessel displayed increased performance. The basic research, comparative analyses, detailed investigations, and the design process with the definition of framework criteria and operative parameters represent the work performed. The overall drilling process was analyzed to anticipate all changes with the ThermoDrill system. The subsurface high pressure intensified jet-drill concept was established, powered by the drilling mud flow with a designed drill bit integrating jetting nozzles.
This conceptual work has been completed successfully. Now the consortium will commence the manufacturing and testing process of the system.
The following tasks where already successfully concluded:
In WP2 the basic concept was researched and investigated with respect to results of previous studies and projects. The basic rock mechanical issues were established, samples were chosen, a rock type for testing was selected, the characteristics of deep geothermal reservoirs were investigated, initial observations on tests were evaluated, and potential drilling and jetting fluid systems were researched. In general, a good understanding of the overall challenges, the processes and framework could be achieved.
In WP3 detailed rock mechanical investigations, jetting tests, scraping and indention tests, simulations, and designs of the drill bit operations were conducted. A comparison of all available technologies and potential alternatives was performed and the two most promising technologies were conceptualized. The result of WP3 was the feasibility of the jetting concept. Based on this, a basic tool concept for downhole pressure intensified rotary jetting tools could be established, and only one single drilling fluid will be deployed, used as drilling mud as well as jetting fluid. This will reduce complexity in terms of tooling and longevity.
In WP4 the basic framework for drilling and jetting fluid was established, taking into consideration all necessary tasks a drilling fluid has to fulfil, paired with the necessary tasks the jetting fluid has to satisfy, e.g. particle size, viscosity, inhibition, corrosion, and abrasion. Out of numerous one especially designed sepiolithe system was chosen for being the optimum choice. Based on this it became clear that the mud cleaning process will require high attention, too.
In WP5 the drill bit design process was started and is still ongoing. The basic concept, after reviewing and testing numerous potential alternatives accompanied by conducting a number of simulations to understand the required geometries and flow parameters, resulted in the selection of a three cone drill bit as basis for the design, implementing up to two high pressure nozzles.
In WP7 a system concept for the testing of the required tools, fluids and their interactions was established. Based on highest HSE standards, all processes and tooling parameters were investigated and reviewed to ascertain that different sections of the developed system will safely interact.
In WP8 HSE aspects are continuously studied in order to properly manage corresponding HSE issues. Main achievements so far are the development of a preliminary HSE risk management plan based on a HAZID study, a risk assessment and the recommendation of countermeasures for the main risks, and the identification of potential HSE requirements which have to be considered during the design phases. Additionally, the main results for the Business process modelling are the definition of the well drilling costs model and the definition of the assumptions for the Reliability Assessment (RAM study).
In WP9 dissemination activities including press releases, website, newsletters, and several scientific publications like presentations at international workshops were carried out.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Exploitation of deep geothermal wells to recover heat or electricity from this renewable and environmental friendly source is an issue almost all over Europe. Today, all technologies are based on one or more boreholes to access this valuable resource at depth.
There are a number of technologies available. However, most of these experience severe problems when confronted with high temperatures and pressures, and the harsh hard rock environment at depth. In particular HSE aspects have to be taken into consideration.
In this context, the ThermoDrill project proposed the combination of proven technologies that can be applied safely under HSE regulations.
The ThermoDrill consortium emphasizes that the results from the first half of the project clearly indicate that the proposed jetting/rotary system will outperform the initially set goals. To our knowledge this is the first time that a jetting system could be tested under borehole conditions and the results could be mapped and directly related to the applied test parameters. A number of additional tests will be conducted to optimize the parameters, but the results to date allow for an optimistic view on the achievable project goals. Up to 500% increase in rate of penetration might be possible.
In terms of socio-economic impact this would allow for cost reductions exceeding the projected 30%, consequently stimulating deep geothermal applications with all their positive aspects from CO2 reduction to base-load energy provision.
In particular with a rate of penetration this high, the ThermoDrill system would highly qualify for the application of interconnecting reservoirs which is nowadays mostly achieved by fracturing. Replacing the highly controversial fracturing technology by the ThermoDrill system would definitely make an impact on future deep geothermal energy production.

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