Dutch authorities release risk assessment of ultra-deep geothermal and EGS

Dutch authorities release risk assessment of ultra-deep geothermal and EGS Geothermal license areas in the Netherlands, Jan. 2019 (source:
Alexander Richter 5 Jan 2021

Netherlands' State Supervision of Mines (SSM) has released a report on study assessing the risk for ultra-deep geothermal and engineered geothermal systems (EGS) in the Netherlands.

What are the risks of ultra-deep geothermal (UDG) and enhanced geothermal systems (EGS – stimulated/ engineered geothermal systems) and how can these risks be limited? These were the central questions in the scientific research commissioned by Netherlands’ State Supervision of Mines (SSM) through the Knowledge Program on Effects of Mining (KEM).

What is the research about?

In the Netherlands, geothermal systems at depths greater than 4 km are considered ultra-deep. Temperatures at these depths can range from 120 to 250 degrees C. At this depth, stimulation of the reservoir rock is often necessary to improve rock permeability or take advantage of the higher permeability of fracture zones. The study identified the increased and additional risks of UDG and EGS compared to conventional geothermal energy for the Netherlands, and described preventive and mitigating measures. The study provides a classification scheme to identify the most important risks for a project and to identify the most suitable preventive and mitigating measures for that specific project.

Research method and results

To arrive at the risk inventory, literature research was carried out and sessions were held with (external) experts. They then worked out the most important 11 risks. Three of these are seismicity; the remaining 8 are related to drilling, testing and boosting the reservoir and producing the hot water. Using a so-called ‘bow-tie analysis’ (a method for identifying risks and formulating appropriate measures), a classification scheme was then drawn up so that risk analyzes can be carried out for concrete projects.

The three risks rated highest in the report (based on impact and probability) are: loss of well control resulting in a blow-out, loss of integrity of the well or above-ground installation, and personnel exposed to a hazardous situation.

Witteveen + Bos (Netherlands) carried out the research in collaboration with subcontractors VITO (Belgium), Q-Con (Germany), Newell (Netherlands) and TU Delft (Netherlands).

The full details on the research program and findings can be found here (attention the date of the “post” does not seem to reflect the content of the post)

What will SSM do with the research?

SSM will take the results of the research into account when assessing and advising on plans and permits for UDG and EGS projects. The classification scheme can help SSM and project implementers to analyze the specific risks for each project and to identify which measures are required for the safe execution of that particular project. SSM will also use the research as input for creating assessment frameworks and standards. Implementers can use the results of KEM-06 in the development of project proposals.

There are currently no UDG projects in the Netherlands. In 2017, a Green Deal was signed by various ministries, Energy Management Netherlands, TNO and consortia of companies. It has been agreed between these parties to work together to increase knowledge about ultra-deep geothermal energy in the Netherlands and make it applicable, so that (pilot) projects can possibly be started. Other initiatives may also emerge in the near future.

All information about SSM’s supervision of geothermal energy and advice on geothermal projects is contained in the Geothermal Supervision Arrangement.

About KEM

The study ‘Risk assessment for UDG and EGS, and an inventory of preventive and mitigating measures (KEM-06) ‘ was carried out as part of the Knowledge Program on Effects of Mining (KEM). The KEM expert panel advised on the research questions, the implementation and the assessment of the research. Participants in the expert panel have strict requirements in terms of independence from the industry and scientific reputation. For more information about KEM and the results of the research, visit

Source: State Supervision of Mines