The Dependence of Geophysical Response on Initial Pore-Network Geometry during Carbonate Precipitation and Dissolution

Abstract:

Reactive transport in porous media can significantly change pore-network geometry, affecting rock properties relevant to energy production, groundwater management, and carbon sequestration. Pore-scale flow simulations have shown that the extent and distribution of such changes depend on initial pore-network geometry and flow parameters. Associated changes in electrical and magnetic properties may allow geophysical techniques to reveal or predict those changes. Geophysical methods such as spectral induced polarization (SIP) and nuclear magnetic resonance (NMR) are sensitive to the pore geometry as well as to fluid-rock interfacial properties.

This research seeks to determine relationships between initial pore-network geometry and the SIP and NMR responses during calcite dissolution and precipitation in carbonate rocks using pore-scale modeling. Synthetic SIP data will be generated by estimating frequency-dependent complex conductivity contributions from the electrical double layer polarization in the pore spaces. NMR responses will be simulated by random-walk simulation of magnetization decay to determine the distribution of transverse relaxation times.

The synthetic SIP/NMR responses from different pore-network geometry will be investigated, for both high and low flow rates, to elucidate the impact of initial pore-network geometry on the geophysical response associated with carbonate precipitation and dissolution. This improved understanding of parametric relationships between carbonate reactive transport and SIP/NMR response will enable more insights to be gained from multi-scale geophysical investigations.