Physical and structural changes in shale associated with supercritical CO2 exposure

Experimental mechanical compaction of reconstituted shale and mudstone aggregates: Investigation of petrophysical and acoustic properties of SW Barents Sea cap rock sequences

“…The inconsistencies regarding the extent, distribution, and significance of halite precipitates, in addition to their influence on the CO 2 phase percolation pathways need to be investigated. While several studies Ott et al, 2015;Yin et al, 2016) have shown that salt crystals precipitate only in the brine phase, and therefore, have an insignificant impact on the flow pathways, several other researchers (Verma and Pruess, 1988;Muller et al, 2009;Miri et al, 2015) have indicated that considerable amount of salt crystals can precipitate in the CO 2 phase. As a result, the clogging models based on the latter studies contradict the former and suggest that in the evaporation-precipitation process of salt formation we may face notable variations in the static and dynamic properties of the porous medium.…”

Simulation and visualization of the displacement between CO2 and formation fluids at pore-scale levels and its application to the recovery of shale gas

“…First, the interaction forces between CO 2 -CH 4 are obtained from the P-R EOS calculation (Liu et al 2015a, b), and the shale matrix-CO 2 /CH 4 interaction (Yin et al 2016) (including the displacement of adsorbed CH 4 by CO 2 and the interaction force of fluids-shale) is acquired from the MD simulation. According to the MD simulation, we can calculate the interfacial tension of CO 2 /CH 4 , the density of CO 2 /CH 4 and the concentration of CO 2 /CH 4 .…”

“…It usually has two states stored in shale, that is, free gas in natural cracks and adsorbed gas on the organic matter surfaces (Yin et al 2016). Generally, a significant part of the shale pores are distributed on the nanometre scale, which results in a large internal surface area (Loucks et al 2009;Kuila and Prasad, 2013;Mosher et al 2013).…”

“…There are many difficulties in shale gas extraction based on the above two issues, and effective methods are urgently required to enhance shale gas recovery (ESGR). Hydraulic fracturing is currently the only fracturing technology utilized in commercial shale gas extraction (Yin et al 2016). However, water-based fracturing fluids have many drawbacks, including aggravating water scarcity and environmental problems (King 2010;Nagel et al 2013;Rutqvist et al 2015).…”

“…11, marked A) (Yin et al 2016). Therefore, these issues cause great difficulties in the accurate simulation of the CO 2 -CH 4 displacement process.…”