Residual CO₂ Trapping in Indiana Limestone

Abstract

We performed core flooding experiments on Indiana limestone using the porous plate method to measure the amount of trapped CO(2) at a temperature of 50 °C and two pressures: 4.2 and 9 MPa. Brine was mixed with CO(2) for equilibration, then the mixture was circulated through a sacrificial core. Porosity and permeability tests conducted before and after 884 h of continuous core flooding confirmed negligible dissolution. A trapping curve for supercritical (sc)CO(2) in Indiana showing the relationship between the initial and residual CO(2) saturations was measured and compared with that of gaseous CO(2). The results were also compared with scCO(2) trapping in Berea sandstone at the same conditions. A scCO(2) residual trapping end point of 23.7% was observed, indicating slightly less trapping of scCO(2) in Indiana carbonates than in Berea sandstone. There is less trapping for gaseous CO(2) (end point of 18.8%). The system appears to be more water-wet under scCO(2) conditions, which is different from the trend observed in Berea; we hypothesize that this is due to the greater concentration of Ca(2+) in brine at higher pressure. Our work indicates that capillary trapping could contribute to the immobilization of CO(2) in carbonate aquifers.

Capillary trapping for geologic carbon dioxide storage – From pore scale physics to field scale implications

“…These results suggest that significant trapping is possible -up to two-thirds of the initial saturation is trapped for both sandstones and carbonates -indicating that CO 2 is the non-wetting phase. This result -significant trapping -is consistent with other experiments with super-critical CO 2 in unconsolidated porous media (Chaudhary et al, 2013;Pentland et al, 2010), core-scale experiments, where the average trapped saturation is measured Krevor et al, 2012;El-Maghraby and Blunt, 2012;Akbarabadi and Piri, 2013, see Section 3) and images of trapped phases at ambient conditions (see for instance, Karpyn et al, 2010;Georgiadis et al, 2013).…”

“…As the value of the constant increases, trapping decreases and there is necessarily less hysteresis in the capillary pressure and relative permeability functions. El-Maghraby and Blunt, 2012).…”

“…This method typically requires careful phase equilibration and fluid re-circulation due to the large number of fluid volumes passing through the sample. This demands a more complex set of peripheral pumps, reactors and a phase separator -compare the experimental apparatus used in ElMaghraby and Blunt (2012) with that of Niu et al (2015) shown in Fig. 9.…”

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

“…Other methods for the equilibration of fluids and rocks, including fluid recirculation 50 , have been proposed in the literature. These methods increase the complexity of the experimental setup, which in turn would have increased the amount of time for each experiment, which would have in turn increased the likelihood that the brine in flow lines would have diffusively desaturated.…”

Pore-Network Simulation of Unstable Miscible Displacements in Porous Media

“…But, most recently, with the global warming becoming a major concern, sequestration of carbon dioxide has become an important area of research. One method for sequestering CO 2 that is currently under study is by injecting it into saline aquifers or depleted oil reservoirs to dissolve the gas into the brine (Orr 2004;Cinar et al 2009;El-Maghraby and Blunt 2013;Altman et al 2013). The process represents a miscible displacement process and, thus, its study is of high importance, even at the laboratory scale.…”