Seismic Interpretation Study of the Jiufotang Formation in Block A

Abstract

The area A is located in the Songliao Basin, and the Lower Cretaceous Jiufotang Formation is the main target layer for oil and gas exploration. Intense The Yanshanian tectonic activity strongly reformed the local strata, resulting in a highly fragmented structural pattern and dense fault development in the area. Relying solely on conventional geological analysis cannot accurately restore the regional tectonic pattern, which poses a major obstacle to the ongoing oil and gas exploration work. In order to deal with these challenges, this study carried out a comprehensive seismic interpretation of the Jiufotang Formation strata and tectonic morphology based on the fully covered 3D seismic data set, combined with local drilling and logging information. A set of geophysical analysis process is adopted, including seismic horizon tracking and fine section structural anatomy to determine faults. The interpretation results show that the study area follows a typical half-graben tectonic framework: the western section is dominated by syncline depressions, and the eastern section is dominated by fault blocks. Two different sets of fault combinations control the entire block. The first set is composed of large normal faults distributed in the northeast direction, which dominates the overall structural layout. The second set refers to the near east-west secondary faults. These faults have many control effects: controlling the sedimentary filling process, acting as a migration channel for hydrocarbon fluids, and forming a lateral closed boundary for oil and gas accumulation. The east and west wing structural belts are selected as the high potential favorable zones for further exploration. This work deepens the understanding of the local structural geological characteristics of the target block and provides a solid geological basis for future drilling deployment and quantitative evaluation of oil and gas resources.