Two PhD positions in understanding sandstone deformation (4 years)

Job description:

In the framework of the Dutch research programme DeepNL on understanding subsurface dynamics caused by human activities, the Department of Earth Sciences at Utrecht University invites applications from highly motivated individuals for two PhD positions within the project titled:

A multi-scale, multi-physics framework for modelling the geomechanical response of sandstone reservoirs to pore fluid extraction

Extraction of fluids, like natural gas, from the Earth's crust frequently results in surface subsidence and tremors, such as observed at the Dutch Groningen Gas Field. However, the long-term surface impact of fluid production cannot be predicted confidently. Within the above project, we will quantify the physical mechanisms causing long-term subsidence and seismicity. As deformation is driven by stresses transmitted across grain-to-grain contacts, microphysical models based on the processes operating at the grain-scale are needed. This project will identify and quantify the main grain-scale deformation mechanism(s) causing inelastic deformation of sandstone reservoir rocks, considering physical (e.g., microcracking, intergranular sliding) and chemical (e.g., stress-driven mineral dissolution) processes, to eventually enable prediction via computer modelling.

We will take a two-fold approach to determine the physical and chemical deformation processes operating at and near stressed grain-to-grain contacts: (1) from experiments conducted at in-situ reservoir conditions, and (2) from microstructures using state-of-the-art micro- and nano-analytical techniques.

The two available PhD positions concern:

PhD position 1 in Experimental Rock Mechanics
Supervisors: Dr S.J.T. Hangx, Dr H.E. King, Prof. Dr C.J. Spiers (promotor)

The aim of this 4-year PhD project is to experimentally determine the deformation processes operating in sandstone reservoir rock under realistic in-situ conditions. The approach will involve conventional mm-/cm-scale triaxial and uniaxial deformation experiments, potentially coupled to real-time X-ray computer tomography (4D-XCT), as well as ?m-scale experiments to study the nano-scale evolution of grain contacts using high-resolution, surface microscopy (AFM) and chemical spectroscopy (Raman, NanoSIMS). The results will be used to develop quantitative, mechanism-based models describing the mechanical behaviour of the material.

PhD position 2 in Microstructural Analysis and Electron Microscopy
Supervisors: Dr O. Plümper, Prof. Dr M.R. Drury (promotor)

The aim of this 4-year PhD project is to look in detail at experimentally and naturally deformed sandstone, using state-of-the-art electron microscopy (EM) techniques including crystallographic orientation (EBSD) and spectroscopic (CL) mapping combined with 2- and 3-D structural and chemical imaging (FIB-SEM, TEM). Experimentally deformed samples will be compared to natural samples from a unique set of drill cores, already available at UU, spanning 50 years of depletion. The results will be directly relevant to the development of constitutive models, such as those developed in PhD position 1.

Throughout the project, there will be a close collaboration between both PhD candidates. The obtained results will be directly useable as a first step towards reservoir-scale upscaling of microphysical modelling, providing the much-needed physical basis to current field-scale models, which incorporate empirical laws. In a broader context, this project contributes directly to the transition from high-carbon fossil fuels, such as oil and coal, towards cleaner energy production using natural gas and geothermal energy extracted from sandstone reservoirs. Improved understanding of the processes controlling reservoir deformation, and accurately modelling this, is highly relevant to assessing and reducing risks of subsidence and seismicity associated with geo-energy production, as well as geological storage of CO2, natural gas, hydrogen fuel and compressed air energy.

More information about the DeepNL programme can be found online on the NWO DeepNL website.

Up to 10% of the candidates' time will be dedicated to assisting in the BSc and MSc teaching programmes of the Earth Sciences Department.

Qualifications:

  • Applicants must not have a PhD degree.
  • Applicants must hold a Master degree in Geosciences, Physics, or Materials Science, and must have good quantitative and programming skills as well as an interest in chemistry.
  • Applicants must have experience of Earth materials research, ideally in rock or materials mechanics or in rock physics.
  • Applicants must have excellent written and spoken English skills and be highly motivated to work in an international team.
  • Knowledge of high resolution analytical techniques is preferred.

Terms of employment:

The successful candidates will be offered a full-time position at first for one year. Depending on a good performance this will be extended to a total period of four years, with the specific intent that it results in a doctorate within this period. The gross monthly salary starts with €2,325 in the first year and increases to €2,972 in the fourth year (scale P according to the Collective Employment Agreement of the Dutch Universities) of employment with a full-time appointment. The salary is supplemented by a holiday allowance of 8% per year and an end-of-year bonus of 8.3%. In addition, we offer a pension scheme, (partly paid) parental leave, collective insurance schemes and flexible employment conditions.

Facilities for sports and child care are available on our main campus (where the Department of Earth Sciences is situated), which is located only 15 minutes away from the historical city centre of Utrecht.

About the organisation:

The Utrecht Faculty of Geosciences offers education and research concerning the geosphere, biosphere, atmosphere and hydrosphere. With a population of 2600 students (BSc and MSc) and 600 staff, the Faculty is a strong and challenging organisation. The Faculty is organised in four Departments: Earth Sciences, Physical Geography, Sustainable Development, and Human Geography & Spatial Planning.

The Department of Earth Sciences conducts teaching and research across the full range of the solid Earth and environmental Earth sciences, with activities in almost all areas of geology, geochemistry, geophysics, biogeology and hydrogeology. The department hosts a highly international group of more than 100 PhD students and postdoctoral researchers and houses a wide variety of world-class laboratories.

Additional information:

For additional information on Position 1 contact Dr Suzanne Hangx: s.j.t.hangx@uu.nl.

For additional information on Position 2 contact Dr Oliver Plumper: o.plumper@uu.nl.

How to apply:

To apply, please follow this link and the guidelines mentioned there. Each application should include the candidate's CV, academic credentials (mark sheets and degree statements), as well as an application letter clearly stating the position you are applying for, why you would like this position and what makes you a suitable candidate, referring to the skills you have or how easy/difficult it would be for you to learn the required skills.

Applications will be accepted until February 28, 2019. Evaluations and interviews are planned soon thereafter. The intended starting date is May 1, 2019, or as soon as possible thereafter.

Online screening may be part of the selection. Commercial response to this ad is not appreciated.

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posted: 06 February 2019     Please mention EARTHWORKS when responding to this advertisement.