Investigation And Applying Of Fracturing With Supercritical Carbon Dioxide In Changqing Tight Sand Gas Field

Considering the strong heterogeneity and water sensitivity,small brittleness,formation pressure and pore throat of unconventional formations in Changqing,ordinary slick water fracturing would cause water block which limits productivity.In this paper,the model of fracture initiation and propagation was established by numerical simulation combined with experimental methods.The feasibility and superiority of supercritical carbon dioxide fractured tight sandstone reservoirs were studied.Research has achieved the following results:1.Numerical simulation results show that the characteristic of low viscous fluid loss of supercritical carbon dioxide makes the wellbore initiation pressure higher,and it has advantages when the formation permeability is low.2.Relative to hydraulic fracturing,carbon dioxide fracturing has a stronger fracturing ability,can produce more complex fracture networks,achieve the effect of volume fracturing;supercritical carbon dioxide fracturing is easier to communicate with natural fracture.3.The corrosive effect of carbon dioxide allows proppant-free fracture conductivity to be maintained at high levels for long periods of time to ensure high daily production and cumulative production.