Microscopic interpretation of oil-water flow based on pore throat characteristics of clastic reservoirs:A case study of the Triassic reservoirs in Sangtamu Oilfield
In order to explain the characteristics of oil-water two-phase flow in the pore-throat system of clastic reservoirs microscopically,thin slice observation,mercury intrusion test and relative permeability test of real core samples from several coring wells were conducted,and the test results were analyzed with statistics.It was found that the Triassic reservoir in the study area mainly develops primary intergranular pores.There are 5 types of pore structures such as large pore coarse throat type,large pore fine throat type,medium pore fine throat type,small pore fine throat type and micropore microthroat type.The average vertex radius of the ultra-low,low,medium,high and ultra-high permeability samples are 1.78 μm,2.98 μm,7.76 μm,24.05 μm and 45.66 μm,respectively.That means the water phase flow resistance differences in ultra-low permeability and low permeability flow units as well as high permeability and ultra-high permeability flow units are about 2 times during water displacing oil in the positive rhythm reservoirs.The water phase flow resistance differences are about 3 times in the combination of low,medium and high permeability flow units.Therefore,the difference in water phase bypass can be determined by the combination types of flow units with different flow abilities in the reservoirs,and thus the distribution location of the bypassed remaining oil can be determined.
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