Based on a novel concept of stiffness described as the combined effect of cementation and electrostatics, we aim to obtain a quantitative model for the effect of pore fluid on chalk strength and fracturing style.
The study will be based on existing geomechanics data supplemented by characterization where needed. Core scale data will be up-scaled by numerical modelling.
The project, a work package under the Danish Hydrocarbon Research and Technology Centre’s Advanced Waterflooding Flagship, aims at understanding the impact in resulting strength and failure mechanisms of different saturating fluids in chalk reservoirs.
Existing results from rock mechanical testing and core flooding experiments on reservoir chalk with a focus on data from the Dan and neighbouring fields will be compiled and critically evaluated.
The evaluation of elastic moduli and rock strength will be done in the light of the new stiffness concept combining degree of cementation and repulsive electrostatic forces arising at the mineral surface, caused by the grain-saturation fluid interaction.
Supplementary laboratory and petrographic characterization such as mineralogy of non-carbonate content, specific surface area by BET and dynamic effective stress coefficient (Biot’s coefficient as measured by Vp and Vs) will be performed to optimize this re-interpretation.
Trends observed in core plug tests will be scaled to reservoir size and a constitutive relation will be established/developed to study the consequence of the water weakening in chalk reservoirs.
The project is funded by The Danish Hydrocarbon Research and Technology Centre.
Supervisor: Prof. Ida Lykke Fabricius, ilfa@byg.dtu.dk
Co-supervisor: Senior researcher, Michael Welch, mwelch@dtu.dk