While much is known about the plastic flow properties that make rocksalt the principal topseal above many gas reservoirs and a good geological storage medium, much less is known about how long it may take for damaged material surrounding wellbores in rocksalt to plastically heal and seal after well abandonment.
The aim of the project proposed here is to obtain quantitative mechanism-based descriptions of the plastic flow (or creep) and self-sealing properties of rocksalt that can be applied in predictive numerical modelling and evaluation of natural well-system sealing behaviour and time-scales after decommissioning.
The project will combine experimental work with microstructural studies to arrive at process-based descriptions of creep-closure and permeability evolution in damaged rock surrounding boreholes and other openings in rocksalt. The stability and transport properties of boreholes that have been sealed with rocksalt plugs will also be considered.
The project will yield process-based descriptions of rocksalt creep and permeability evolution that are tailor-made for incorporation into numerical codes, in use by TNO and industry, for modelling wellbore performance, thus enabling self-sealing of abandoned wells in rocksalt to be evaluated as a natural sealing technology. TNO will also develop a simple software tool, based on fundamental work by UU, for rapid performance evaluations.