Experimental Study On Oil-Water Phase Relative Permeability Of Tight Oil Core

With the continuous growth of the world's oil and gas resources demand,China's external dependence on crude oil is already around 70%.Tight oil and gas resources with great potential have gradually become a hot field for unconventional oil resource exploration.China's tight oil resources are abundant,a comprehensive understanding of the tight flow law of tight oil,has great guiding significance for the exploration and development of tight oil resources in China.In this paper,capillary force curve method and non-steady-state displacement method were used to study relative permeability of tight reservoir cores.The capillary force curves of cores at different water saturations were obtained by centrifugation experiments and the oil-water relative permeability was calculated by the fractal model.Combined with low-field NMR monitoring technology,compared the difference between tight cores and sandstones,then analyzed the flowable range at core scale.The non-steady state method was at a low flow rate in water flooding experiments,using nuclear magnetic to detect changes in seepage inside the core,introducing the capillary force parameter to obtain the oil-water relative permeability curve considering the capillary force,then used T₂ spectrum to discuss the difference between core oil and water distribution in centrifugal experiments.The study of oil-water phase relative permeability law in tight oil core has further attempted and explored,and get the following conclusion:(1)The irreducible water saturation of the tight core is higher than that of the conventional sandstone core,the oil-water co-flow range is narrower,and the relative permeability is lower.(2)The low-field nuclear magnetic resonance can be used to monitor the fluid distribution inside the core.The tight core has a wider T₂ signal spectrum than the conventional sandstone,and the flowable range is mainly distributed between 1-100ms.(3)Both the capillary force curve method and the non-steady state experimental method are good methods for measuring the relative permeability of tight core.Due to the difference in oil displacement,the core oil displacement efficiency measured by the non-steady state experiment is higher than that of the centrifugal experiment.