Abstract: Large-scale conglomerate bodies are developed in the fourth member of the Shahejie Formation in the Niuxintuo Area of the western Liaohe Sag. Influenced by the depositional environment, the reservoir performance of different facies varies greatly, which restricts the in-depth exploration of conglomerate reservoirs in this area. To this end, the petrological characteristics of the reservoir and the main controlling factors of the high-quality reservoir were studied for the clastic rocks of the Shahejie Formation in the Niuxintuo Area using a combination of core, thin section identification, physical property testing and logging and other analytical methods. The result shows: The rock types of the fourth member of the Shahejie Formation in the Niuxintuo Area are dominated by feldspar sandstone and lithic feldspar sandstone, and the reservoir pores are mainly composed of primary pores, secondary dissolution pores and fractures. The reservoir is generally a medium-low porosity and low-permeability reservoir. The physical properties of the reservoir are controlled laterally by deposition and longitudinally by burial depth. The comprehensive analysis shows that sedimentation, burial depth and fracture are the main controlling factors of the high-quality reservoir in the study area, and the front edge of the fan delta is a favorable reservoir facies zone, which is the key area for the next step of exploration. The research results have certain guiding significance for the in-depth exploration of the Niuxintuo Area and similar sags.

Key words: reservoir characteristics, main controlling factors, Shahejie Formation, Niuxintuo Area, western sag