Impacts of mineral composition and pore structure on spontaneous imbibition in tight sandstone

Abstract Spontaneous imbibition is a fundamental mechanism to figure out the rock-fluid interplay during waterflooding and hydraulic fracturing. Mineral composition and pore structure play significant roles in imbibition efficiency, but how these parameters influence the oil production efficiency still is a myth. This research conducted the spontaneous imbibition experiments combined with low-temperature adsorption and nuclear magnetic resonance to (1) study how minerals and pore structures impact fluid movement features for tight sandstones; (2) systematically investigate the contribution to oil recovery of different pores' types and the impact of pore connectivity on spontaneous imbibition. The results show that the brine is inclined to attach hydrophilic minerals because of the wettability, increasing the imbibition efficiency. Additionally, with the tiny pores’ development, the oil is more easily replaced by the brine due to strong capillary pressure. Last, as the mainstream imbibition area grows, the oil is preferentially displaced by the brine. The research provides insights into how mineral compositions and pore structures can influence spontaneous imbibition efficiency and improves the understanding of the complicated interaction between fluid and minerals in tight sandstones.