PhD position on Quantitative constraints on pre-production reservoir stresses in Groningen (1.0 FTE, 4 years)

The Department of Earth Sciences at Utrecht University is currently seeking a highly motivated PhD candidate to work on the research project "Quantitative constraints on pre-production reservoir stresses in Groningen". This project was selected for funding by the Dutch Research Council (NWO) in the context of the DeepNL research programme, which aims to improve the fundamental understanding of the dynamics of the deep subsurface under the influence of human interventions.

An interdisciplinary team involving Rob Govers (Tectonophysics) and Douwe van Hinsbergen (Global Tectonics & Paleogeography) from Utrecht University, and Wouter van der Wal (Glacial Isostatic Adjustment) from Technical University Delft seeks a PhD student to work in a collaborative programme on estimating natural stresses in the gas reservoir of Groningen (Netherlands). The Groningen gas field ranks amongst the 10 largest in the world. About 50% of the gas was produced, in some years at high rates, during the first three decades without inducing seismicity. The year 1991 was a tipping point as induced earthquakes started to occur in the reservoir at increasing numbers and magnitudes, and the events continue today. Understanding this tipping point is important. Was the magnitude of natural stress in the rock low, and did it take 30 years of production to increase the stresses to a level where they exceeded the strength of the faults? Or, alternatively, where the natural stresses in the rock high, and did it take 30 years before the pre-existing fault where rebroken, and are they weaker now? The evolution of post-production seismicity hinges on answering these questions, which is why we aim to constrain the natural stresses before 1960.

Natural stresses are the consequence of tectonic processes and may also have a footprint of the last ice age. Physically consistent models of the entire Eurasian plate will allow us to estimate the tectonic forces and to identify mechanically weak and strong sub-regions that result in the intraplate stress field. Finite element model estimates of stress and velocities will be compared with stress and GPS observations. We will use Bayesian methods to estimate the likely range of the direction and magnitude of natural stress in Groningen from the models and the observations. Possible stress contributions will be assessed from separate models of glacial isostatic adjustment after the melting of the Fennoscandian and British-Irish ice sheets. The geologically rapid tectonic reorganisation of Mediterranean plate boundaries will be another source of stress in the Netherlands that we intend to investigate. If successful, we expect this new type of models and workflow to drive innovation in other contexts also (e.g., geothermal energy and tectonic studies).
You will be expected to publish the results in papers in top journals. You will work in the international Tectonophysics team, led by Govers, of PhD students and a Model Support Technician. Up to 10% of your 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 and mutually agreed upon recruitment, which will reflect your training needs and career objectives.