Abstract: In view of the difficulties in energy supplement after large-scale fracturing by stimulated reservoir volume of tight sandstone reservoirs, a large artificial three-dimensional core physical model and a physical simulation lab module designed and manufactured by ourselves were used to study the optimization of the energy supplement methods for tight sandstone reservoirs. The experimental results showed that during the fracturing development of tight sandstone reservoirs, the formation energy was greatly lost and could be supplemented by water or gas injection effectively; the larger the fractures in the formation, the more conducive to crude oil seepage and the wider spreading scope of the subsequent supplemented energy, which was helpful to further improve the oil recovery; CO₂ was better than active water in terms of being used as imbibition medium which was selected in terms of improving flooding efficiency and the sweep efficiency; the CO₂ stimulation has achieved a significant oil recovery enhancement in the field test. Therefore, CO₂ stimulation, as an effective way of energy supplement, has a good application prospect in the development of tight oil reservoirs. In this paper, the seepage law of horizontal well fracturing in tight sandstone reservoirs was analyzed and the best imbibition medium after large-scale fracturing in tight sandstone reservoirs was preferably selected, providing an important theoretical basis for the development design of tight sandstone reservoirs.

Key words: tight sandstone, energy supplement mode, oil displacement efficiency, fracture, CO₂ stimulation, active water