Wang Xiuwei 1 , Yang Xiaochen , Wu Chenlin , Hu Chenguang , He Yijian , Jiang Zhou , Zhang Fan , Wang Chao , Zhu Yushuang
World Geology. 2026, 45(3): 452-466.
The reservoirs of the Linhe Formation in the Linhua well area, Hetao Basin, exhibit strong heterogeneity, significant variations in petrophysical properties, and complex pore structures, which have restricted
hydrocarbon exploration and development. Based on 12 sandstone samples collected from the study area, a comprehensive investigation was conducted by integrating multiple analytical approaches, including casting thin-section
petrography, scanning electron microscopy (SEM), mercury intrusion capillary pressure (MICP), and waterflooding
visualization experiments using real-sandstone micromodels. This study systematically characterized pore types,
fractal characteristics, and waterflooding flow responses, clarified the relationships among fractal dimensions, reservoir properties, and flow response, revealed the controlling effects of fractal characteristics on waterflooding
pathways and displacement patterns. The results show that, based on petrophysical properties and oil-test characteristics,
the reservoirs in the study area can be classified into three types: TypeⅠ(high-quality reservoirs), TypeⅡ(moderatequality reservoirs), and Type Ⅲ (poor-quality reservoirs). TypeⅠreservoirs are dominated by primary intergranular
pores, with locally developed enlarged dissolution pores and a certain proportion of micropores, forming a wellconnected effective pore network with distinct preferential flow channels. Type Ⅱ reservoirs are characterized by the
co-development of intergranular pores and dissolution pores, with local coexistence of macropores and micropores.
Type Ⅲ reservoirs are dominated by tiny intergranular pores and intercrystalline micropores, with small pore sizes,
poor connectivity, and an overall compact structure. The average fractal dimensions of Type Ⅰ, Type Ⅱ, and
Type Ⅲ reservoirs are approximately 2. 88, 2. 81, and 2. 75, respectively, corresponding to complex, moderately
complex, relatively simple and compact pore systems. The visualized waterflooding experiments indicate that the
three reservoir types exhibit “finger-like to network-like,” “finger-like to uniform,” and “network-like to uniform”
displacement patterns, respectively. Overall, fractal dimensions shows a good correspondence with waterflooding
flow response: higher fractal dimensions are generally associated with complex pore structures, well-developed
preferential flow channels, and stronger heterogeneous flow, whereas lower fractal dimensions commonly correspond to
slow and relatively uniform flow under compact pore-structure conditions. The integrated application of multiscale
pore-structure characterization, mercury-intrusion-based fractal analysis, and waterflooding visualization experiments using real-sandstone micromodels establishes the relationship between reservoir fractal characteristics and displacement patterns, reveals the controlling effect of static pore structure on dynamic flow response, and provides a
basis for fine reservoir evaluation, differentiated development, and well placement in the study area.
