Time Frame: 2017-2020
Funding: BMBF Programm Geo:N - Geoforschung für Nachhaltigkeit
Principle Investigator: Moritz Ziegler and Oliver Heidbach
Kooperationen: Frank Schilling, Birgit Müller, Malte Westerhaus (KIT), Karlsruhe, Deutschland; Andreas Henk , TU Darmstadt, Deutschland; UNIPER, Düsseldorf, Deutschland; Thomas Röckel, Piewak & Partner, Bayreuth, Deutschland
In the course of the German change of energy policy, the mechanical requirements for underground gas storage will increase due to higher amplitude fluctuations during storage operations. For the assessment of site safety and the recommendation of suitable operating parameters, the impact of cyclic loads on the geological components of the storage facility are of key importance. We investigate of the interaction between the natural far-field stress field and the stress changes induced by the gas storage, with a the key motivation to assess the reactivation of disturbances and the resulting induced seismicity.
The aim of this project is an interdisciplinary investigation of the complex geomechanical processes on different scales that affect the reliability of subsurface gas-storage. The interplay between the regional stress field and the cyclic loading of technical installations are regarded in order to determine suitable operational parameters. The main focus is to research the hypothesis that an increase in frequency and amplitude of storage operations (due to the transition to renewable energies) affects the integrity of subsurface gas-storages. The main goal is to optimize the storage operations in order to increase the safety of the storage operations without a reduction in functionality or capacity.
A holistic, systemic approach is pursued that employs experiments in laboratories, technical centres, and in the field that characterise the complex rheological properties of gas storages. This knowledge helps to establish and calibrate numerical models (THMC modelling and geomechanical modelling including biological processes) that allow predictions on the systems behaviour. A validation is achieved by a comparison of predicted (modelled) and observed deformation. This is used to investigate whether observed deformation can be used as a proxy for ageing processes of the gas storage and are suitable as an early warning system in terms of integrity. Our contribution is to investigate the interplay between the far field stress state and stress changes in the vicinity of the storage. We will simulate subsidence scenarios in order to predict possible reactivations of pre-existing tectonic faults.
Gas Storage Modelling | Scetch shows the changes of porosity (upper figure) and permeability (lower figure) due to gas storage (Arrufo et al. 2014).