Speaker
Description
Reservoir changes in bulk porosity and permeability induced by mineral precipitation can reduce the efficiency of energy production and CO2 storage operations. The efficiency of these operations will be greatly improved if precipitation-induced changes to the bulk reservoir porosity and permeability can be accurately predicted via models that factor the influence of measurable variables like the initial PSD, transport regime, and mineralogical composition of the rock pore surfaces. This study evaluates the influence of PSD and transport regime on precipitation-induced changes to PSD and permeability in geologic media through micro-computed tomography (µCT) and small angle neutron scattering (SANS) analysis of microporous quartz-rich Berea sandstone and calcite-rich Indiana limestone rock samples was conducted before and after calcite precipitation was induced under conditions representing high Péclet number and low Péclet number transport regimes, while subjecting the samples to typical reservoir temperature and pressure conditions. Post-experiment, a reduction in bulk porosity and permeability was observed in both samples after precipitation was induced at high and low Péclet number conditions. The pore size distribution (PSD) obtained from µCT analysis revealed that at the micro-scale, this resulted in the samples being characterized by a right-skewed shift in PSD after precipitation was induced. However, under low Péclet number conditions, the rock samples were observed to have a greater decrease in bulk porosity due to the filling of large and small microscale pores. Results from µCT analysis revealed that when precipitation is induced under high Péclet number conditions, a greater decrease in bulk porosity and permeability will be observed in rock samples with a high pore connectivity. Nanoscale pore structure results from SANS analysis of microporous calcite-rich Indiana limestone samples also reveal that nanoscale pore volume reductions due to a precipitation-induced clogging of large to small nanopores are greater when the transport regime is advection-limited. Overall, such nanoscale to microscale insights on the coupled PSD and transport dependence of precipitation-induced permeability reduction is crucial to accurately modelling reservoir porosity and permeability evolution during engineering applications such as CO2 storage, hydrocarbon recovery, and geothermal energy production.
| Country | United States of America |
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