Migration behavior of supercritical and liquid CO₂ in a stratified system: Experiments and numerical simulations

Abstract

Multiple scenarios of upward CO2 migration driven by both injection‐induced pressure and buoyancy force were investigated in a horizontally and vertically stratified core utilizing a core‐flooding system with a 2‐D X‐ray scanner. Two reservoir‐type scenarios were considered: (1) the terrestrial reservoir scenario (10 MPa and 50°C), where CO2 exists in a supercritical state and (2) the deep‐sea sediment reservoir scenario (28 MPa and 25°C), where CO2 is stored in the liquid phase. The core‐flooding experiments showed a 36% increase in migration rate in the vertical core setting compared with the horizontal setting, indicating the significance of the buoyancy force under the terrestrial reservoir scenario. Under both reservoir conditions, the injected CO2 tended to find a preferential flow path (low capillary entry pressure and high‐permeability (high‐k) path) and bypass the unfavorable pathways, leaving low CO2 saturation in the low‐permeability (low‐k) layers. No distinctive fingering was observed as the CO2 moved upward, and the CO2 movement was primarily controlled by media heterogeneity. The CO2 saturation in the low‐k layers exhibited a more sensitive response to injection rates, implying that the increase in CO2 injection rates could be more effective in terms of storage capacity in the low‐k layers in a stratified reservoir. Under the deep‐sea sediment condition, the storage potential of liquid CO2 was more than twice as high as that of supercritical CO2 under the terrestrial reservoir scenario. In the end, multiphase transport simulations were conducted to assess the effects of heterogeneity on the spatial variation of pressure buildup, CO2 saturation, and CO2 flux. Finally, we showed that a high gravity number ( Ngr) tended to be more influenced by the heterogeneity of the porous media.

Capillary pressure heterogeneity and hysteresis for the supercritical CO2/water system in a sandstone

“…the scale at which all reservoir processes operate) (Shafer, 2013). Most significantly, such developments have revealed that results must be interpreted by acknowledging the fact that capillary pressure heterogeneity results into local saturation development (Graue, 1994;Chaouche et al, 1994;Shi et al, 2011;Pini et al, 2012;Alemu et al, 2013;Oh et al, 2015;Ott et al, 2015), which may lead to apparent flow rate effects on macroscopic properties of relative permeability and residual trapping (Perrin and Benson, 2010;Krevor et al, 2011;Kuo and Benson, 2015;Reynolds and Krevor, 2015). Accordingly, improved laboratory workflows are now being developed that make use of such wealth of information by e.g., referring to the internal structure of the sample and in-situ observations, to obtain accurate parameterisation of rock and multiphase properties (Pini and Benson, 2013a).…”

Characterizing the Impact of Fractured Caprock Heterogeneity on Supercritical CO$$_2$$ Injection

“…A lower density scCO 2 bubble sitting below higher density water leads to the water having a higher pressure at the bottom of the scCO 2 than the top and this difference creates a force gradient that pushes the scCO 2 upwards. Numerous field and numerical studies have shown that buoyancy forces can play a critical role in the vertical flow of scCO 2 [7,10,32,39].…”

Carbon Dioxide (CO2) Dissolution Efficiency During Geological Carbon Sequestration (GCS) in Randomly Stratified Formations

“…(2009), and Oh et al. (2015) studied the effect of heterogeneity on capillary trapping, ignoring dissolution. Other authors (Doughty & Pruess, 2004; Doughty et al., 2001; Gershenzon, Ritzi, et al., 2015) have only analyzed dissolution trapping in a few idealized depositional settings.…”

“…The effect of permeability stratification during the injection of CO 2(g) in GCS has been observed in several works, which have demonstrated that, after injection, a major proportion of CO 2 -rich phase can enter and move preferentially through relatively high permeability conduits or channels, creating erratic patterns (Chadwick & Noy, 2010;McGuire et al, 1995;Obi & Blunt, 2006;Oh et al, 2015;Rasmusson et al, 2015;Stalkup & Crane, 1994;Tsang et al, 2001). Data from Sleipner field site (Gregersen, 1998) in the North Sea, which is a reservoir formed by interbedded sandstones and mudstones, indicated that the injected CO 2(g) was mostly present in several disconnected layers of relatively high permeability with a thickness of about 10 m (Chadwick et al, 2004(Chadwick et al, , 2005.…”