PhD Studentship: REcycling of waste geomaterials and their application as primary
constituents for high-level CONstructions (RECON)

We are looking for an enthusiastic and highly motivated PhD student with proven interest and background in geomechanics and/or construction materials fields. This is an exciting opportunity to be part of a joint PhD research supported by the EUTOPIA PhD Cotutelle programme. The PhD study will be carried out at the CY Cergy Paris Université (CY) in France and the University of Warwick (UoW) in the UK. The doctoral student will spend half of the PhD in CY and half of the PhD in UoW.

More information in this attachment.

PHD PROJECT:  UNCERTAINTY QUANTIFICATION OF GEOMECHANICALLY SENSITIVE RESERVOIRS USING PHYSICS-INFUSED MACHINE LEARNING

What is the problem?

When we use the subsurface to store CO2 or Hydrogen, the rocks can deform inelastically as the reservoir conditions change – processes well described in geomechanics. But this permanent strain can lead to significant leakage and to induced seismicity risks during operation and/or long term storage. At worst, these risks pose a substantial threat to property and health – so much so that regulators and investors may halt projects before they start as we can’t correctly estimate the geomechanically-derived risks.

The key technical challenge for most storage reservoirs is to accurately quantify uncertainties and risks associated with geomechanical property changes from a few computer model forecasts. Geomechanical simulation software is complex and data-intensive, each run taking many hours to days. Such long run times make statistically thorough methods to quantifying uncertainty impractical. In most circumstances, we can’t afford the thousands of required model realisations. So such risks may be misestimated or even missed.

The longest model run times occur when we couple simulations of fluid flow (production and injection) with geomechanical simulations to predict how a development plan may alter the reservoir rocks properties and how this will impact fluid movement and field operations. To solve the system of equations for fluid flow and geomechanics together, we need to connect very different modelling approaches, the differences in the solvers typically precluding full coupling. Instead, the packages interact by running separately but simultaneously and passing data back and forth between iterations. This is a technically monumental challenge and the run times of the models are far longer than the combined times of each model run separately.

To accurately quantify uncertainties in geomechanically sensitive reservoirs we must run many more models than we do today, exploring a more diverse set of geological scenarios. But to run more models, we must significantly improve the efficiency of coupling fluid flow and geomechanical simulations. Machine learning provides one solution: once trained on an appropriate data set it can capture complex, non-linear systems very rapidly.

PhD position available at the Unit of Geotechnical Engineering of the University of Innsbruck in our doctoral program ‘Natural Hazards in Mountain Regions’. More details under:

https://www.uibk.ac.at/geotechnik/staff/schneider-muntau/job_advertisement_phd_dp_natural_hazards.pdf

We are looking forward to the applications of motivated people!

Applications are invited for a PhD student at the University of Liège, to work on Unsaturated soil mechanics – Experimental and constitutive focus on desiccation cracking in fine-grained soils.

The PhD candidate will also take part in teaching activites related to soil and rock mechanics courses. The research and teaching assistant position is granted for a first term of two years, renewable for up to 2 further periods of 2 years.

Project description

The mechanics of desiccation cracking is a complex hydro-mechanical process, induced by soil drying in partially or totally strain-constrained conditions. Desiccation cracks may affect significantly the hydro-mechanical properties of fine-grained soils (strength weakening, increased compressibility, increased permeability), leading to potential geotechnical issues (landslide triggering, soil erosion, leakage of impermeable barrier, …).

In the framework of unsaturated soil mechanics, this study will investigate the conditions of desiccation cracks triggering, their propagation and their aperture evolution, from experimental and constitutive approaches. Suction control techniques, image analysis and tensile strength testing will be developed. A particular attention will be devoted to the determination of tensile strength criterion at various suctions, through innovative experimental developments

The experimental characteristics will then be encapsulated in constitutive laws and implemented in a finite element code. The numerical simulations will incorporate the modelling of water evaporation, the hydro-mechanical response of soil upon drying, the tensile strength criterion and the impact on the presence of the crack mechanical and hydraulic response of the ground. Finally, the methodology will be applied to study the conditions of occurrence of desiccation cracking in full-scale problems (earthfill dike, nuclear waste disposal gallery, landfill waste disposal, agricultural soils, …).

Requirements and application procedure

The position is open to graduated students (Master degree) in Civil Engineering, Geosciences or related disciplines.

Applicants should have a high level of proficiency in written and spoken English. The successful candidate is also expected to learn French during his first two years.

Applications must be sent by email to Prof. Frédéric Collin (F.Collin@uliege.be). It should include a motivation letter, a CV and a short abstract of the Master thesis. Please contact Prof. Frédéric Collin if you need more information.

Applications are welcome before 12^th July 2021. The starting date is at the latest the 1^st October 2021.