Enhanced fossil hydrogen energy recovery through liquid nanofluid huff-n-puff in low permeability reservoirs

Abstract Surfactant huff-n-puff can enhance fossil hydrogen energy recovery from low permeability reservoirs. However, due to the high cost and adsorption of surfactant, its commercial application is limited. Liquid nanofluid (LNF) has been widely used in hydraulic fracturing since it can significantly reduce the adsorption. In this study, a series of experiments were conducted to investigate the potential of LNF huff-n-puff. First, the spontaneous and dynamic imbibition with NMR was conducted to study the imbibition oil recovery for the LNF. The results showed that the spontaneous imbibition recovery of LNF is 1.43 folder than brine. Besides, the LNF enters the small pores first in spontaneous imbibition. In the process of dynamic imbibition, the LNF enters the larger pore with smaller resistance first, then enters the small pore around the flow path. After dynamic imbibition, the imbibition recovery in small pores increased 54%. Moreover, pressure transmission tests (PTT) were conducted to evaluate the increasing rate of reservoir pressure. This work provides a new view of how surfactant or LNF functions in the process of huff-n-puff.