Nano-SiO2 enhanced slickwater fracturing fluid for improved imbibition recovery in tight gas reservoirs: Performance and mechanism

Abstract

Inspired by the exceptional performance of nanomaterials in oilfield development, yet it is rarely applied in tight gas reservoir. In this study, focusing on the tight gas reservoir of the Liuyangbao, Ordos Basin, a slickwater fracturing fluid was synthesized by incorporating nano-SiO2 and surfactant to enhance its stability and activity, aiming to optimize the utilization efficiency of slickwater. The prepared SiO2-enhanced slickwater fracturing fluid exhibited excellent interfacial regulation properties involving surface tension reduction (71.65–28.31 mN/m) and wettability alteration (69.3–21.5º). In addition, SEM images indicated that the self-assembled nano-SiO2 adsorbed on the core surface, sequentially forming a large number of micro/nano structures in “spot adsorption”, “sheet adsorption”, “lobe adsorption” and “cluster adsorption” shapes, altering the original pore structure. Meanwhile, LP-N2GA results showed an upward shift in the hysteresis loop of isotherms after nano-SiO2 was adsorbed on the core samples, with a considerable increase in specific surface area (SSA) and transitional pores. Moreover, the system showed an outstanding capacity for imbibition gas production, and finally recovered 78.2 % (∼21.4 % higher than slickwater system). The underlying mechanism responsible for the system enhanced gas recovery were attributed to capillary pressure, structural disjoining pressure and Jamin effect. This work provides feasibility of the application of nano-SiO2 in the development of tight gas reservoirs.