Study On Increasing Production Mechanism Of CO₂ Fracturing In Tight Oil Reservoir

As a non-hydraulic fracturing technology,CO₂ fracturing has the advantages of water conservation,reduced reservoir damage,enhanced oil recovery and CO₂ storage,and is a cutting-edge technology to improve the fracturing transformation effect of tight sandstone reservoirs.At present,the domestic study of CO₂ fracturing is in its infancy.Therefore,it is necessary to study the mechanism of CO₂ fracturing and production increase in tight oil reservoirs.In this chapter,the X ray diffraction experiment is used to analyze the mineral composition of the long 7 sections of tight sandstone and evaluate the brittleness.Based on small size true triaxial hydraulic fracturing system,we carry out physical simulation experiment for the core sample of Chang7 tight sandstone.At the same time,the fracture morphology was described by three methods:CT scanning imaging,sample surface observation and sample dissection.Secondly,the mathematical model of solid-liquid two phase flow is established,and the solution is solved by CFD method.The sand carrying law of CO₂ fracturing seam is analyzed,and the distribution characteristics of sand bank in the fracture are obtained by the CO₂ fluid carrying proppant.On this basis,the influence of each parameter on the sand carrying law in the CO₂ fluid seam is systematically analyzed.In this paper,the combination of experimental analysis and numerical simulation is used to study the fracture mechanism of CO₂ fracturing and the law of sand-carrying in the seam.The research results will provide a theoretical basis and technical support for the formulation of the CO₂ fracturing improvement plan for tight oil reservoirs.