Abstract:The interlayers developed in the gravel-bearing sandstone segment of Tazhong 4 Oilfield have seriously hampered the development of the oilfield. Based on the observation of cores and thin sections, combined with previous studies, this paper concludes that there are three major categories and seven subcategories of the origin of the interlayer in the study area. According to lithology, electrical properties, physical properties, occurrence and distribution, the interlayers with different origins are further divided into silty interlayers, calcareous interlayers and physical interlayers, and the physical and electrical standards for identifying the interlayers in non-coring wells are determined. Finally, based on the single well interpretation, the relationship between the development of the interlayer and the sedimentary environment, sedimentary cycle and faults is revealed. With the deepening of water, the physical interlayers decrease rapidly from 5 to 1 sublayer, while the silty interlayers increase; In each base-level descending cycle, the silty interlayers are easy to develop at the top, while the physical interlayers are easy to develop at the bottom; The calcareous interlayers are controlled by faults.