Microscopic pore structure and solid-liquid force of Chang 73 shale in Ordos basin
To address the problems of the pore structure and solid-liquid force characteristics of the Chang 73 submember shale reservoir in the Ordos Basin,firstly,the pure shale reservoir samples were studied by focusing ion beam electron microscopy,computed tomography and atomic force microscopy.Secondly,the multi-scale 3D reconstruction model of shale was established with Avizo software,and the pore structure characteristics of shale were quantitatively analyzed.Finally,a method for measuring the adhesion of shale reservoir by the interaction of solid and liquid was proposed,and the adhesion between crude oil and pore wall was measured.The results show that the Chang 73 reservoir is developed with intergranular pores,intra granular pores,and organic matter pores.The main shapes of organic matter pores are strip shaped,crescent shaped,and elliptical.Organic matters have the highest roughness,followed by felsic,pyrite,and fillers.At the micrometer scale,the development of bedding seams can be clearly observed.At the nanoscale,there is no significant difference in the pore structure characteristics of samples with different shale structures,and the pore throat morphology is mostly sheet and strip shaped.The adhesion between organic matter and crude oil is the highest,followed by the adhesion between felsic matter and crude oil,and the adhesion between bedding planes and crude oil is the lowest.The average adhesion of the three types is 0.098,0.063 and 0.041 μN,respectively.The difficulty of starting the wall crude oil in the Chang 73 shale reservoir is relatively high,which explains from a mechanical perspective why this area is a key area for in-situ conversion.
shale oilpore structureseepageadhesion forceorganic poreatomic force microscope
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