Abstract:Although the research on deformation band in porous sandstone has made great progress in recent years,it is still a relatively fuzzy problem to distinguish and define a single deformation bands and clusters of deformation bands.This paper clarifies this issue and discusses its influence on hydrocarbon migration and exploitation. Methods: Taking the shear-enhanced compaction bands (SECB) and compactional shear bands (CSB) developed in the high porosity sandstone of honghuatao formation of Upper Cretaceous in Yuan’an Graben as examples,the characteristics and differences of single deformation band and clusters of deformation bands are systematically analyzed from macro and micro perspectives.Results: The results show that although the length,width,displacement and bulge height of the single deformation band are significantly smaller than those of the deformation band clusters,the characteristics of deformation bands of different kinematic types are different.SECB has no central cataclastic band,and the grains are mainly moderately fractured,and most of them are discontinuous cataclastic cores.The characteristics of single SECB and clusters of SECBs are similar,but the heterogeneity of SECB clusters is stronger,and the decrease of porosity and permeability is limited.A single CSB usually has a central cataclastic band.The degree of grain crushing and the width of the margin transitional band depend on the shear stress, and are often accompanied by micro shear fractures.Under the microscope,the clusters of CSBs can clearly be identified different central cataclastic bands,interband area and micro shear fractures,and occasionally,subtle S—C structures and discontinuous slip surface can be seen.Conclusions: It is not only necessary to distinguish single deformation band and clusters of deformation bands according to their scale,but also need to distinguish deformation band clusters from deformation band arrays and networks of distributed deformation bands according to their band density,and identify them accurately according to their microstructural characteristics.The deformation bands in porous sandstone will change the physical properties of reservoir and may have an impact on oil and gas migration and exploitation.