Low-pressure tight gas reservoir liquid CO2 and CO2 foam system mixed fracturing technology

The invention relates to a low-pressure tight gas reservoir liquid CO2 and CO2 foam system mixed fracturing technology. The low-pressure tight gas reservoir liquid CO2 and CO2 foam system mixed fracturing technology comprises the following steps that in the stage of prepad fluid, pure liquid CO2 and pure liquid CO2 carrying a small amount of propping agent are alternately injected into a shaft toconduct stratum fracture initiation for fracturing, and after entering the stratum, the pure CO2 reaches the supercritical state under the action of temperature and pressure; in the stage of sand-carrying fluid, a cross-linking low-concentration low-residue thickening agent solution carrying the propping agent and the liquid CO2 are mixed through a tee joint and injected into the shaft, and sand fracturing is conducted by means of the high viscosity feature under the gas-liquid two-phase condition; in the stage of displacing fluid, after sanding is ended, base fluid is utilized to made foam fracturing fluid in the sha