Deep sandy conglomerate reservoirs in the Dongying sag have significant potential for oil and gas exploration. Under standing the spatial distribution and formation mechanism of petroleum in these reservoirs is crucial for comprehending deep oil and gas accumulation processes. This study employed organic geochemistry, reservoir fluid inclusions, and basin simulation to clarify the characteristics and differences of deep oil and gas, revealing their distinct formation mechanisms and models. Results show a vertical distribution of hydrocarbon fluids in the Yanjia area of the Dongying sag, with dry gas, condensate gas, and light oil occurring from deep to shallow. In contrast, the Shengtuo area is dominated by oil phase, with varying associated gas components in different reservoir types. The differentiation of deep hydrocarbon fluids is attributed to variations in generation, reconstruction, and preservation processes. The hydrocarbon accumulation process in the sandy conglomerates has a strong succession. The thermal evolution history of the source rock determines the initial petroleum phase, while subsequent secondary alteration influenced by the fluid environment plays a significant role. The overlapping transport fan creates an open fluid environment that facilitates gas invasion, promoting vertical phase differentiation of oil and gas. Conversely, a relatively closed environment tends to maintain a single- phase oil and gas system. In addition, fault transport can lead to the loss of light components in oil and gas, further contributing to hydrocarbon fluid differentiation. Based on the understanding of the distribution characteristics and genetic mechanisms of hydrocarbon fluids, two distinct formation models were established. The first model highlights the vertical differentiation of hydrocarbon phase state types, primarily driven by thermal evolution and secondary alteration.The second model emphasizes gas component differentiation, influenced by thermal evolution and fault transport. Understanding the differential formation mechanisms of deep hydrocarbon fluids in the Dongying sag can provides scientific guidance for predicting the distribution of different hydrocarbon fluid types in deep formations.