The Shunbei No. 4 fault zone is located in the central part of the Shuntuoguole Low Uplift. The reservoir type in this zone is a condensate gas reservoir controlled by fracture zones. This type of reservoir is rare both domestically and internationally. The phase characteristics of the condensate gas reservoir exhibit a clear north-south differentiation. In-depth research on the phase characteristics and the main controlling factors of this differentiation can provide valuable insights for the exploration and development of similar condensate gas

reservoirs. This study employed various technical methods

including PVT (pressure-volume-temperature) high-pressure physical property experiments

organic geochemical analysis

and fluid inclusion analysis and testing. The results showed that the crude oil in the Shunbei No. 4 fault zone was characterized by a low freezing point

low sulfur content

and medium-to-high wax content. Within the zone

natural gas exhibited differential distribution in terms of methane molar fraction

gas-oil ratio

gas dryness coefficient

and CO

2

molar fraction. PVT experiments indicated that the reservoir was a condensate gas reservoir with a large difference between formation pressure and dew-point pressure

classifying it as an unsaturated reservoir. The critical temperature and pressure in the northern section were significantly higher than in the middle and southern sections

showing a decreasing trend from north to south. From the perspective of hydrocarbon source rocks and reservoir formation

the differential enrichment of condensate gas reservoirs in the Shunbei No. 4 fault zone is primarily controlled by multiple sources of hydrocarbon supply and multiple phases of reservoir formation.