Multiphase flow through fractured porous media has been of a great interest for decades because fractures can be the dominant flow paths in a wide range of environments, from groundwater flow and geothermal transport to fractured oil reservoirs and caprock integrity for gas and carbon storage projects. The fundamentals of multiphase flow in fractures have been studied both experimentally, mainly by means of synthetic fractures, and numerically, by assuming linear relative permeability curves. It is already known that fracture relative permeabilities are not linear functions of saturation, but still, this assumption is used due to the lack of proper relative permeability curves. A consequence of this simplification is large errors in simulated predictions and a mismatch with experimental results. With the aim of providing these crucial relative permeability curves to be used in the numerical simulations and to describe the different phase flows behavior in a fracture, multiphase core-flooding experiments are conducted in a fractured basalt rock in the context of CO2 injection. These experiments are combined with two different scan imaging techniques. X-Ray CT imaging provides information about the structure of the fracture and PET (Positron Emission Tomography) imaging shows how the fluids flow through it. The former allows us to calculate the fracture aperture distribution while from the later we obtain the phases saturation distribution. As a result, the change of relative permeability with the degree of saturation can be calculated and the nature of the multiphase fluid interactions in the fracture can be described.
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