Tekst kun på engelsk
The project explores CO2 plumbing systems of reservoirs and cap rocks by integrating observations from actively leaking and former, exhumed reservoir-seal systems employing field, laboratory and reservoir modelling studies. The aim is to implement observed flow and leakage patterns combined with observed diagenetic status and rock strength assessments in 3D simulation models. Steps toward this aim include:
- High-resolution field studies of spatial porosity and permeability distributions guiding subsurface CO2 flow evidenced in exposed reservoir-caprock systems, targeting: (i) depositional facies and architecture (sedimentary bypass), and (ii) fault zone composition, architecture and fracturing (structural bypass),
- Assess scaling from mm-cm scale outcrop observations to high-resolution, representative element volume reservoir models through sensitivity testing, to establish required resolution in a workflow that can be compared with typical hydrocarbon-reservoir models,
- Comparison of diagenetic effects in brine-filled sediments vs. CO2 filled sandstone and shale, through micro-textural analysis and laboratory flow-rig testing of samples from reservoirs,
- Investigate geomechanical properties of fault rocks and tight caprocks in order to establish constraints for fault- and top-seal rupture and fault reactivation,
- Investigate how reservoir pressure and time-dependent diagenetic impacts caused by CO2 migration affect geomechanical properties; in particular shear strength of the reservoir, but also fault rocks
Bleached sandstone bed in the Curtis Fm. at Humbug Flats, Utah.
We will integrate the field observations, spatial patterns of diagenesis and geomechanical properties in a case-true 3D reservoir model of the study area. The model will provide a fundamental, conceptual understanding of CO2 plumbing systems, covering aspects such as temporal impact of CO2 plumes on flow and model forecasting capability. It will further facilitate sensitivity studies on selected parameters to map out their impact on reservoir quality, integrity and responses – thus providing a tool for forecasting suitability of a given site for CO2 storage.
We address the objectives through five work packages targeting sub-objectives:
- Rock properties: petrophysical properties of reservoir-caprock systems, focusing on CO2 leakage and flow properties of sedimentary facies, faults and fractures at two sites in Utah, USA (Little Grand Wash Fault and Humbug Flats),
- Diagenetic effects: analysis and comparison of pristine vs. CO2 exposed sandstones and shales,
- Geomechanics: establish frictional properties, shear and tensile strength of fault rocks and tight caprocks by lab study, and analyze critical loads on reservoir model scale, linked to diagenetic weakening of the reservoir successions that could lead to reservoir collapse,
- Reservoir modelling and simulation: generate high-resolution geo- and simulation models based on field observations, diagenesis and geomechanical properties, and conduct systematic sensitivity studies on selected parameters and upscaling.
Research partners: University of Oslo (lead), Uni Research CIPR, Western State Colorado University, Utah State University, Norwegian Geotechnical Institute, Colorado School of mines, University of Parma.