Details of Award
NERC Reference : NE/C002938/1
Feedback between physical and chemical processes during dehydration reactions
Grant Award
- Principal Investigator:
- Professor DR Faulkner, University of Liverpool, Earth Surface Dynamics
- Co-Investigator:
- Professor J Wheeler, University of Liverpool, Earth, Ocean and Ecological Sciences
- Grant held at:
- University of Liverpool, Earth Surface Dynamics
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Natural Resource Management
- Global Change
- Environmental Risks and Hazards
- Science Topics:
- Properties Of Earth Materials
- Tectonic Processes
- Mantle & Core Processes
- Geohazards
- Abstract:
- When rocks dehydrate, if the volume of evolved water exceeds the reduction in the solid volume component, excess fluid pressures result. This fluid pressure causes weakening and embrittlement if it cannot be transported away, and is thought to result in instability (earthquakes) in subduction zone settings. Experiments to date have not explored in detail the kinetics of dehydration reactions, where on the grain scale, anisotropic stress states occur because of the difference between normal stress on grain-grain contacts and grain pore contacts. Factors affecting the reaction rate (kinetics) must be quantified, as fluid pressure changes resulting from the progression of the reaction will feedback on the reaction rate and control the mechanical strength of the system. Another key aspect to the development of excess pore fluid pressure development concerns the fluid flow pathways that are available to drain the produced water away. These are likely to be controlled by the spatial development of the reaction (because it involves a solid volume change), which will be dictated by fluid pressure gradients and the applied stress to the system, which may produce oriented fractures at high fluid pressure, or preferred zones of dehydration coincident with planes of maximum shear stress. The processes that occur during dehydration under the application of applied differential stress are currently poorly understood. Consequently large scale models are unable to predict the macroscopic mechanical response in dehydrating systems. We propose to address the above problems using a combined experimental, theoretical and micrsotructural approach to the data from which will then feed into a more realistic large scale model. We will perform experiments in a high pressure deformation apparatus, that mimics burial depth (2 / 8 km) and allows careful control of the pore fluid pressure. We will measure the reaction progress under a range of confining pressures (equivalent to burial depth) and pore pressures. A theoretical thermodynamic model will be calibrated against these measurements which will then be able predict the reaction progress at all conditions on the sample scale. Differential stress will then be applied in experiments to characterize how it affects the reaction rate and the spatial distribution of the reaction which can be observed microstructurally. Finally we propose to take our small scale measurements and theoretical predictions and apply them on the large scale to predict the mechanical stability of dehydrating systems under a number of different boundary conditions.
- NERC Reference:
- NE/C002938/1
- Grant Stage:
- Completed
- Scheme:
- Standard Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Standard Grant
This grant award has a total value of £223,307
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Staff | Total - Other Costs | Total - Indirect Costs |
|---|---|---|---|
| £3,517 | £136,341 | £20,733 | £62,715 |
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