Fractal Characteristics and Controlling Factors of Tight Sandstone Reservoirs Based on High-pressure Mercury Injection Experiments
The characteristics of micro-pore structure are the focus of reservoir research,which is of great significance to the study of micro-heterogeneity and the exploration and development of the reservoir in the later stages.Taking the Chang 6 tight sandstone reservoir in the Yan'an-Ganquan area in the southern Ordos Basin as an example,through casting thin sections,scanning electron mi-croscope analysis,X-ray diffraction and high-pressure mercury intrusion experiments,combined with fractal theory,the fractal charac-teristics of the target reservoir were determined,and the relationship between fractal dimension and reservoir physical properties,pore characteristics and mineral composition was discussed.The results show that the reservoir pores of the Chang 6 member in the study ar-ea are mainly intergranular pores and dissolution pores,which are ultra-low porosity and tight reservoirs.The fractal dimension of the reservoirs is generally greater than 2.5,the pore structure is complex,and the sorting property is poor,strong homogeneity.The fractal dimension has a good correlation with the pore-throat characteristic parameters.The larger the fractal dimension,the uneven distribu-tion of pores,poor connectivity,and weaker storage capacity and seepage capacity.The relationship between fractal dimension and mineral composition there is also a good correlation between them.Mineral composition and its content are the influencing factors that determine the complexity of pore throats,which in turn reflect the quality and pore structure characteristics of the reservoir.
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