Abstract: The disclosure discloses a foam fracturing fluid with double interface layers of a phlogisticated air-liquid CO2 for shale gas development, and a preparation method thereof. The foam fracturing fluid is prepared from a liquid CO2 phase, a gas phase and a nano-enhancer; the liquid CO2 phase is formed by dissolving a mixture of gas-soluble foaming agents in liquid CO2; the gas phase is a gas mixture of phlogisticated air and saturated vapor of the liquid CO2; the nano-enhancer is an aqueous solution of a mixture of hydrophobic silica nanoparticles, a cosolvent and a water-soluble surfactant. In the fracturing fluid prepared by the present disclosure, the phlogisticated air was encapsulated by the liquid CO2 to form an interface layer, the liquid CO2 was further encapsulated by the nano-enhancer to form the other interface layer, which enhanced the structural stability of the fracturing fluid while achieving high viscosity and thermal stability.

Abstract: The disclosure discloses a foam fracturing fluid with double interface layers of a phlogisticated air-liquid CO2 for shale gas development, and a preparation method thereof. The foam fracturing fluid is prepared from a liquid CO2 phase, a gas phase and a nano-enhancer; the liquid CO2 phase is formed by dissolving a mixture of gas-soluble foaming agents in liquid CO2; the gas phase is a gas mixture of phlogisticated air and saturated vapor of the liquid CO2; the nano-enhancer is an aqueous solution of a mixture of hydrophobic silica nanoparticles, a cosolvent and a water-soluble surfactant. In the fracturing fluid prepared by the present disclosure, the phlogisticated air was encapsulated by the liquid CO2 to form an interface layer, the liquid CO2 was further encapsulated by the nano-enhancer to form the other interface layer, which enhanced the structural stability of the fracturing fluid while achieving high viscosity and thermal stability.