PhD position Multi-Scale Geological Reservoir Characterisation and Modelling

Background: Geological reservoirs used for producing or storing energy are heterogeneous. Characterising and quantifying geological heterogeneities is challenging because sampling scales (e.g., thin sections, plugs, cores) are different from the scales where petrophysical properties need to be defined (i.e., the scale of a grid block in a reservoir model). This gives rise to major uncertainties, especially in heterogeneous formations such as the Rotliegend of The Netherlands, because reservoir models are used to investigate how geological heterogeneities impact production rates and production risks. A fundamental challenge is that current reservoir modelling workflows almost always underestimate geological heterogeneity and hence provide unrealistic uncertainty bounds. The unique database of the Groningen Rotliegend reservoir in the Netherlands provides a once-in-a-generation opportunity to develop an efficient and scientifically-based methodology that allows us to represent the key geological heterogeneities in reservoir models through geologically-informed upscaling and better constrain uncertainties in model predictions. Such advanced geoscience research will enable us to execute future geoenergy projects safely and sustainably, and is needed to earn trust among different stakeholders and societal actors. The CrossScale project, which is part of the DeepNL programme funded by the Dutch Research Council, hence aims to bridge across scales and disciplines to develop a new upscaling methodology for better reservoir models and provide a new deliberation approach that improves the communication between scientists and societal stakeholders.

Project description: We are seeking to recruit two PhD candidates with a strong interest in interdisciplinary research that not only combines geoscience with reservoir engineering but also considers the societal impact of geoenergy applications to work on the following complementary aspects of the CrossScale project:

• PhD project 1 based at the Energy and Sustainability Research Institute at the University of Groningen: Characterising sedimentary heterogeneities across scales
• PhD project 2 based at the Department of Geoscience and Engineering at the Delft University of Technology: High-resolution geological modelling and numerical simulations of geoenergy applications.

PhD project 1 will map the Representative Elementary Volume (REV) scales of Rotliegend reservoirs by developing a methodology that incorporates geological and petrophysical data (mostly at scales up to 10s of centimetres). PhD candidate 1 will determine the key data necessary to define the REV scales for a specific reservoir setting. A comprehensive set of multi-scale data from the DeepNL projects will be collated. This will involve reviewing plug-scale data (thin-sections, geomechanical and poro-perm data), core-scale data (geomechanical and short-wave infrared spectroscopy data, core photographs, facies/lithology classifications), well-scale data (well-logs, lithostratigraphy, compaction data), and reservoir-scale data (outcrop analogues, facies models, geophysical characterisations). By integrating and analysing these data, REV scales for geomechanical and flow properties of the Rotliegend reservoir will be proposed. To address data gaps when validating geomechanical REV scales, PhD candidate 1 will conduct rock deformation and flow experiments on laminated Rotliegend samples at intermediate scales (e.g., above core scale, between plug and core scale) to obtain key mechanical and flow properties. Considering the inherent noise and bias in some of the data, the uncertainty associated with the resulting REV scales will be quantified. Through this work, PhD candidate 1 will help to answer the following research questions:

• What are the relevant REV scales for flow and geomechanics for the geological heterogeneities within the Rotliegend of the Groningen field?
• How can the identified REV scales be integrated into an upscaling methodology to improve the prediction of flow and geomechanical behaviours of the Rotliegend?
• What are the key geological heterogeneities that need to be characterised to define REV scales and execute upscaling methods reliably for other geoenergy applications in the Rotliegend?

Both PhD candidates will work closely together to iteratively calculate and validate the effective properties for the different REV scales and corresponding upscaling strategies using both, geological characterisation and numerical simulations. This will result in a geologically-informed upscaling workflow that will be further utilised by two postdoctoral researchers; they will analyse how improved upscaling techniques impact the reliability of forcasting the behaviour of geoenergy projects, respectively how improved model forecasts can be best communicated to non-technical stakeholders and decision makers.

Organisation
The University of Groningen has an international reputation as a dynamic and innovative centre of higher education offering high-quality teaching and research. Balanced study and career paths in a wide variety of disciplines encourage the 35,000 students and researchers to develop their own individual talents. Belonging to the best research universities in Europe and joining forces with prestigious partner universities and networks, we are truly an international place of knowledge.

The Faculty of Science and Engineering harbours a kaleidoscope of disciplines and research strengths. Our programmes in research and education range from nanomaterials and biomachinery to astronomy, from mathematics to pharmacy, from neurosciences to computer science, and from molecular and evolutionary biology to marine biology.

The Energy and Sustainability Research Institute (ESRIG) is a highly multidisciplinary institute performing research on energy and sustainability. Activities include experimental and model studies as well as studies into the societal interaction with scientific knowledge. The research of the small Geo-Energy group within the ESRIG is focusing on the safe, sustainable utilization of the subsurface for energy production and storage as well as carbon utilization and storage.

The successful applicant will hold a relevant MSc degree in geoscience or applied geology. Ideally, this candidate will already be able to contribute their experience in reservoir description and characterisation as well as a basic understanding of geomechanics and fluid flow processes in geological formations. Experience in reservoir modelling is also welcomed.

Due to the interdisciplinary and collaborative nature of the CrossScale project, excellent communication and interpersonal skills, as well as the desire to work in a diverse and interdisciplinary environment, are an essential requirement for both positions. Both candidates should also have sound quantitative approach to subsurface geoscience challenges and bring some programming experience (e.g., Python).

Equal opportunities
We are acutely aware that we are a diverse society and not every talented student will have had the same opportunities to advance their careers. We therefore pledge to fully account for any particular circumstances that the applicants disclose (e.g. parental leave, caring duties, part-time jobs to support studies, disabilities etc.) to ensure an inclusive and fair recruitment process that does not rely purely on common research metrics.

The successful candidate will be offered, following the Collective Labour Agreement for Dutch Universities:

• a salary of € 2,770 gross per month in the first year, up to a maximum of € 3,539 gross per month in the fourth and final year for a full-time working week
• a holiday allowance of 8% gross annual income
• an 8.3% year-end bonus
• a full-time (1.0 FTE) position for four years; first, you will get a temporary position of one year with the option of renewal for another three years; extension of the contract is contingent on sufficient progress in the first year so that successful completion of the PhD thesis within the contract period is to be expected.

A PhD training programme is part of the agreement and the candidate will be enrolled in the Graduate School of the Faculty of Science and Engineering.

Candidates are expected to start preferable before 1 June 2024