Experimental evaluation of pore size, mineral composition, and transport regime controls on mineral precipitation in porous geologic media
Research Poster Engineering 2025 Graduate ExhibitionPresentation by Chima Ukaomah
Exhibition Number 150
Abstract
Precipitation-induced reductions in reservoir bulk porosity and permeability are detrimental to subsurface fluid extraction operations. Reactive transport models are limited in their ability factor precipitation-induced pore size distribution changes from the microscale downwards. In this study, core flood experiments undertaken at high and low Péclet number transport regimes were used to simulate the precipitation of calcite in limestone samples under high advection-limited and low advection-limited transport regimes. In addition, the advection-limited precipitation of calcite was also induced in a quartz-rich sandstone sample to evaluate mineralogy controls on precipitation. Results from micro-CT and small angle neutron scattering (SANS) analysis of the limestone samples pre- and post-reaction, revealed that when the precipitate and pore surfaces are similar in composition, a transport regime that is less advection-limited will induce a greater reduction in bulk porosity and permeability. This reduction will be due to the filling of large and small microscale pores, with a reduction in the volume of nanoscale pores also occurring due to a similar pore filling mechanism at the nanoscale. In addition, a comparison of microscale PSD changes induced by advection-limited precipitation reveals that compared to mineralogy, pore connectivity will have a greater influence on precipitation-induced reduction in the bulk porosity and permeability. These observations emphasize that the use of non-destructive methods to evaluate nanoscale and microscale PSD changes induced by precipitation is the key to the development of an accurate empirical model that can be used to accurately predict the precipitation-induced evolution of porosity and permeability in porous geologic media.
Importance
Scientists have struggled to predict how the formation of minerals in micrometer and nanometer sized holes can cause a reduction in the available fluid flow pathways when fluids are being extracted from underground rocks. Our observations emphasize the need for scientists to use methods that can see micrometer and nanometer sized holes in rocks if they are going to be able to predict the reduction in fluid migration pathways that occur when fluids are being extracted from underground rocks. This is because datasets generated from such methods are the key to generating an empirical model that can accurately relate the reduction in fluid migration pathways to the formation of minerals in nanometer and micrometer sized holes.