Numerical Simulation Study on the Phase Distribution Characteristics of CO2 Fracturing Fluid inside Cracks
The CO2 dry fracturing technology utilizes pure liquid CO2 for sand carrying fracturing construction,and transforms the reservoir,this technology has been widely applied on site.However,the phase distribution of CO2 fracturing fluid within fractures has not been systematically studied.The physical model of two-dimensional fractures is established by using fluid simulation software to analyze the phase distribution of CO2 fracturing fluid during the fracturing process.The research results indicate that during the fracturing process,CO2 fracturing fluid exists in two phases of liquid CO2 and supercritical CO2,and the distribution of supercritical CO2 is the main one;when CO2 fracturing fluid is filled with cracks,as the distance between the measuring point and the wellhead increases,the CO2 temperature first increases and then tends to stabilize;CO2 fracturing fluid enters the crack,and when the fracturing construction is completed for 20 min,the temperature of CO2 in the crack reaches the formation temperature;the lower the formation temperature,the slower the heat absorption of liquid CO2,the longer it takes to reach the supercritical phase,and the farther the distribution area of supercritical CO2 is from the fracture.