Understanding and quantifying uncertainty is crucial for the development of Direct Use Geothermal Systems (DUGS). Subsurface uncertainty remains even in extensively explored geological basins and is related to data, models and spatial properties. In DUGS uncertainty is present on three different levels: a) subsurface characterization, b) development scenarios and c) economic inputs. The data available for DUGS is usually based on previous exploration activities and is often more restricted than for hydrocarbon projects. Due to the lower value of hot water compared to hydrocarbons, the business case of DUGS is more challenging compared to oil and gas projects. This affects the funds available for exploration and additional data acquisition, increasing the uncertainty on the production scenarios and putting the economic viability of some projects at risk.

In this project you will work on determining the properties that are most important for uncertainty quantification and thus enable reliable model predictions and robust decisions in the development of DUGS. An outline of the project goals is as follows:

- Classifying and ranking the impact of subsurface, development and economic inputs on safety, energy generation, lifetime and economic output of DUGS using coupled Thermal-Hydraulic-Mechanical-Economic (THME) models and Distance-Based Global Sensitivity Analysis (DGSA)

- Distinguish and explain how the interplay between convection and conduction behaves across different scales: from laboratory-sample scale to full-field scale models.

- Characterizing and assessing the thermal response of heterogeneous reservoirs with different (N/G) and heterogeneity levels. This will allow the confident use of simplified models when their output matches facies-based or stochastic

Background:

The mechanical behaviour of reservoirs and faults can be influenced by the pressure and temperature changes introduced by geothermal operations. Mechanical stability can be assessed using Mohr-Coulomb theory that considers pressure changes and thermally induced stress changes. The thermal, hydraulic and mechanical interactions and their impact on safety, energy output, lifetime and economic performance require a coupled Thermal-Hydraulic-Mechanical-Economic (THME) model to be fully evaluated.

Geology remains a strong controlling factor for geothermal system performance. Nonetheless, a systematic study of geological sites representative of conduction-dominated settings is not presented in literature.

To reduce the computational load and the parameter space required to quantify uncertainty, a sensitivity study is required. Conventional One-At-a-Time sensitivity is not able to capture the interaction between parameters that is crucial for such a coupled system. Therefore, a Global Sensitivity Analysis (GSA) is needed in order to account for the high dimensionality of the problem. The computation burden of GSA can be overcome by approximating the sensitivity by the distance between the outputs of stochastic models (distance-based global sensitivity analysis)

Understanding the need for detailed facies modelling is important for the predictive capacity of models. To capture the distribution of flow properties in the reservoir and the related uncertainty different methods can be used in increasing level of complexity considering porosity and permeability: averaged homogeneous models, layered homogeneous models, facies-based stochastically generated models and  process-based generated models.

Previous studies have shown the importance of net-to-gross (N/G) for DUGS lifetime and recent studies have shown a good agreement in representing heterogeneity with different methods for heterogeneous, high N/G models. However, the different ways for representing heterogeneity have not been systematically studied across a large range of N/G ranges (~15-90%) and heterogeneity levels.

The successful applicant is expected to have an MSc degree in geoscience, reservoir engineering, applied physics or equivalent. The understanding of both the geology and subsurface fluid flow are highly relevant for this work. Programming in Python is a requirement. Experience with reservoir simulation and geo-modelling are welcomed. Excellent communication and interpersonal skills are an essential component for this position. The position requires that you grow to become an independent researcher in the field of geothermal energy.

Doing a PhD at TU Delft requires English proficiency at a certain level to ensure that the candidate is able to communicate and interact well, participate in English-taught Doctoral Education courses, and write scientific articles and a final thesis. For more details please check the Graduate Schools Admission Requirements.

Fixed-term contract: 4 years.

Doctoral candidates will be offered a 4-year period of employment in principle, but in the form of 2 employment contracts. An initial 1,5 year contract with an official go/no go progress assessment within 15 months. Followed by an additional contract for the remaining 2,5 years assuming everything goes well and performance requirements are met.

Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities, increasing from € 2541 per month in the first year to € 3247 in the fourth year. As a PhD candidate you will be enrolled in the TU Delft Graduate School. The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills.

The TU Delft offers a customisable compensation package, discounts on health insurance and sport memberships, and a monthly work costs contribution. Flexible work schedules can be arranged. For international applicants we offer the Coming to Delft Service and Partner Career Advice to assist you with your relocation.

Delft University of Technology

Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context.

At TU Delft we embrace diversity as one of our core values and we actively engage to be a university where you feel at home and can flourish. We value different perspectives and qualities. We believe this makes our work more innovative, the TU Delft community more vibrant and the world more just. Together, we imagine, invent and create solutions using technology to have a positive impact on a global scale. That is why we invite you to apply. Your application will receive fair consideration.

Challenge. Change. Impact!

Faculty Civil Engineering & Geosciences

The Faculty of Civil Engineering & Geosciences (CEG) is committed to outstanding international research and education in the field of civil engineering, applied earth sciences, traffic and transport, water technology, and delta technology. Our research feeds into our educational programmes and covers societal challenges such as climate change, energy transition, resource depletion, urbanisation and the availability of clean water, conducted  in close cooperation with a wide range of research institutions. CEG is convinced that Open Science helps to achieve our goals and supports its scientists in integrating Open Science in their research practice. The Faculty of CEG comprises 28 research groups in the following seven departments: Materials Mechanics Management & Design, Engineering Structures, Geoscience and Engineering, Geoscience and Remote Sensing, Transport & Planning, Hydraulic Engineering and Water Management.

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To discover more about Research, Education, our Lab facilities and your possible future colleagues at the Department of Geoscience and Engineering, check out our website: www.tudelft.nl/en/ceg/about-faculty/departments/geoscience-engineering