The Department of Earth Sciences currently seeks a potential applicant for a PhD position to work within the research programme WarmingUP (https://www.warmingup.info/) on the theme 'Geothermal energy in the built environment'. 
Induced seismicity can occur in geothermal energy production, and is documented in many high enthalpy production systems around the globe and in settings where hydraulic fracking has been applied for the enhancement of reservoir quality. In the Netherlands, low enthalpy systems are being developed in permeable reservoirs without the need for reservoir stimulation. However, in the -tectonically active- South-Eastern part of the country few small events with magnitude up to M~2 have occurred, which may likely be related to geothermal operation, and have resulted in suspension of the geothermal production systems in that region.

Consequently, also in face of induced seismicity associated with Groningen Gas production, there is public concern over the possible occurrence of induced seismicity in geothermal operations. Are the ongoing and planned geothermal operations in the Netherlands safe in terms of potential risks for induced seismicity? Can it be precluded that over lifetime progressively more seismic events may manifest itself only decades after the start of production such as in Groningen Gas production?

For existing and new geothermal production systems in the Netherlands, in WarmingUP we aim to improve our understanding on potential hazards for induced seismicity, over the production lifetime. Therefore, predictive models are needed, which can assess the likelihood for the occurrence of induced events and the exceedance of threshold magnitudes over the lifetime of geothermal energy production. To this end, the PhD will co-develop, with a multi-disciplinary team of scientists in WarmingUP, model capabilities for changes in stresses and associated seismic hazards for typical geothermal reservoirs in the Netherlands. The models will be tested and validated on case studies, representative for the Dutch setting. A key focus of the research is to enhance fundamental insight in the correlation between (the absence of) seismic hazards and specific subsurface in-situ conditions (e.g. stress, structures, reservoir and over-/underburden rock properties) on one hand and operational conditions on the other hand.

The predictive models build on the  extension of geomechanical models available in TNO (e.g MACRIS for prediction of stress changes in structurally complex reservoirs as a function of pressure and temperature change), as well as event-rate en hazard prediction models on the basis of workflows developed for Groningen, and including logic tree concepts.

For subsurface parametrisation, the PhD candidate will contribute to the national compilation and analysis of subsurface in-situ (or baseline conditions) which are of significant relevance for the effect on seismic hazards and includes (amongst others) in-situ stress, base line seismicity, distance and orientation of faults, reservoir conditions (fracture of matrix porosity) and thermo-mechanical properties.

The research team is highly interdisciplinary and includes Prof. Jan-Diederik van Wees (supervisor, UU/TNO) and Dr. Fred Beekman (UU), and a supervisory and advisory team from WarmingUP, including Induced Seismicity Project leader Brecht Wassing (TNO), Dr. Thibault Candela (TNO), Dr. Jan ter Heege (TNO). The research will be performed at Utrecht University and TNO.

Up to 10% of the candidate's time will be dedicated to assisting in the BSc and MSc teaching programmes of the Department of Earth Sciences. A personalised training programme will be set up, mutually agreed on recruitment, which will reflect the candidate's training needs and career objectives.

The successful candidate should have an MSc (or equivalent) in Earth Sciences before the start of the appointment. A strong background in geomechanics, tectonics, and/or physics is essential. Experience with one or more of the following topics would be an advantage: modelling of geomechanical or tectonic processes and programming, including Python. A broad interest in geosciences, and the willingness and capacity to interact in a multidisciplinary team, are essential. The candidate should be proficient in both spoken and written English, and preferentially be able to communicate in Dutch as most of the project documentation is Dutch.

You will be offered a full-time PhD position, initially for one year with extension to four years in total upon a successful assessment in the first year, and with the specific intent that it results in a doctorate within this period. The gross salary starts with €2,395 per month in the first year and increases to €3,061 per month in the fourth year of employment (scale P according to the Collective Employment Agreement of the Dutch Universities) for a full-time employment.  
Besides that, you will receive a holiday allowance of 8% and a year-end bonus of 8.3%. Utrecht University also has an appealing package of terms of employment, including the choice for a good balance between work and private (a good arrangement for leave, among other things), possibilities for development and an excellent pension scheme. More information on working at Utrecht University can be found here

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