Movable Oil Characteristics of Shale Reservoir in Songliao Basin
A total of 19 rock samples from the Qingshankou Formation shale oil reservoir in the Songliao Basin were subjected to high-speed centrifugation and nuclear magnetic resonance experiments.A reservoir movable oil evaluation method was established,revealing the characteristics of movable oil in the target shale oil reservoir.Combining high-pressure mercury injection experiments and scanning electron microscope experiments,the reasons for the characteristics of movable oil in the target reservoir were analyzed from the perspective of pore structure.The results show that as the permeability decreases,the proportion of the right peak in the T2 spectrum of the experimental core decreases,and the movable oil decreases.The average percentage of movable oil in block 1 core is 17.88％,and in block 2 core is 14.56％.Both cores with different permeabilities contain a certain amount of micrometer-scale flow channels.The movable oil controlled by micrometer-scale throats/fissures in the two blocks is 9.34％and 5.7％,respectively.The proportion of movable oil controlled by 0.10～1.0 μm throats is relatively low,averaging 4.05％in block 1 and 3.22％in block 2.The proportion of movable oil controlled by throats smaller than 0.1 μm is 4.49％in block 1 and 5.64％in block 2.The proportion of movable oil controlled by throats larger than 1.0 μm is higher in block 1 than in block 2,while the proportion of movable oil controlled by throats smaller than 0.1 μm is higher in block 2.High-pressure mercury injection indicates that the target shale oil reservoir has a certain proportion of larger throats development,but the overall matrix throats are very small,with the main throats distributed between 5～30 nm.The average throat radius of the six cores is 30 nm,and the distribution of reservoir throats is in good agreement with the distribution of movable oil.The throat distribution characteristics determine the distribution characteristics of movable oil.Scanning electron microscope results indicate that the target shale oil reservoir has a dense matrix and small throats.Most of the pores are isolated,and some reservoirs have developed micro-fractures such as fissures and inter-fissures,indicating a strong heterogeneity.A certain proportion of micro-fractures are developed in the reservoir,so a certain amount of crude oil can be expelled when centrifugal force is low.However,the overall matrix of the reservoir is dense and the throats are small,resulting in a relatively low proportion of total movable oil.
shale oil reservoirhigh-speed centrifugationnuclear magnetic resonancehigh-pressure mercury injection
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维普
