Structural control on fluid migration in inverted sedimentary basins
von Florian Duschl
Datum der mündl. Prüfung:2018-11-19
Betreuer:Dr. Alfons van den Kerkhof
Gutachter:Prof. Dr. Martin Sauter
Gutachter:Prof. Dr. Jonas Kley
EnglischAnalogue studies in earth sciences are crucial for the understanding of various geological environments that may serve as future storage sites for carbon dioxide captured at an industrial scale. The feasibility of CCS pilot sites and of future investments dealing with CCS technologies depends on our detailed knowledge about processes taking place in reservoir rocks, from micro to macro scale. Important parameters to describe the reservoir quality of natural analogues are (a) the caprock integrity, (b) the petrological and petrophysical properties of the reservoir rock, and (c) the composition, the physical properties and the mobility of fluids present in the reservoir rock, with special emphasis in CO2. In order to describe the quality of a reservoir rock supposed for carbon dioxide storage we compare four different natural analogues (two tight CO2-reservoirs, two outcrop analogue) in similar structural settings (i.e. inverted sedimentary basins) with a special focus on the long-term reservoir behaviour on a geological time scale, possible failure mechanism (leakage) in varying stress regimes, and the impact of the leakage on the reservoir quality. Key subjects and relevant rock properties considered for this study include: geologic and tectonic history of the reservoir, mineral composition of the reservoir rock, microfabrics, fluid chemistry and origin, timing of fluid migration, reservoir pressure and temperature conditions, water-rock-interaction, cementation history (porosity/permeability), fracture mechanics (fracture gradient/paleo-stress field), as well as fracture networks and related mineralization. Therefore, a variety of different methods was applied and a new methodology was developed, that helped to gain as much information on the respective reservoir rocks and their geologic history as possible. The reasonable combination of various established laboratory techniques and the use of state-of-the-art basin modelling software lead to an innovative approach for a comprehensive reservoir characterization, that may help to improve our understanding of long-term carbon storage and carbon utilization in geological formations. The aim of this study is to prove the applicability of this newly developed approach and to detect uncertainties in its methodology that will allow us to narrow down the limitations of the proposed method. Since carbon capture and storage and utilization technologies represent a relatively new industry to reduce CO2 pollution in a worldwide context, their public acceptance is still low. Thus, the validity of reservoir quality predictions appears to be fundamental for the assessment of future injection sites.
Keywords: Basin inversion; Fluid migration; Microfabric analysis; Carbon capture and storage; Hydrothermal mineralization; Fracture analysis