Distribution and Genesis of Permian Overpressure in the Eastern Fukang Sag, Junggar Basin

Yujiao Ren

doi:10.54691/h4dps298

Authors

Yujiao Ren

DOI:

https://doi.org/10.54691/h4dps298

Keywords:

Junggar Basin; Fukang Sag; Permian; Overpressure Genesis.

Abstract

Overpressure is widely distributed in the Permian strata of the eastern Central Depression in the Junggar Basin and is closely related to hydrocarbon reservoirs. However, its genesis, evolution process, and controlling effects on reservoir formation remain unclear. Using comprehensive mudstone compaction curves and vertical effective stress-density crossplots, the formation mechanisms of abnormal high pressure in the Permian strata of the study area were analyzed. On this basis, the basin modeling method was applied to reconstruct the overpressure evolution for different lithologies in the Permian strata, summarize its planar distribution patterns, analyze the impact of overpressure on hydrocarbon reservoirs within the area, and further summarize the hydrocarbon accumulation models under the control of Permian overpressure in the study area. The results indicate: (1) The Permian strata in the study area develop weak to strong overpressure, with significant differences in the magnitude of overpressure developed in different structural locations. The overpressure is strongest in the sag area, followed by the slope zone, and relatively weak in the uplift area. (2) The genesis of overpressure varies significantly among different lithologies. The overpressure in the source rocks of the Lucaogou Formation is attributed to hydrocarbon generation and undercompaction; the overpressure in the reservoir of the Upper Wuerhe Formation is attributed to overpressure transfer and undercompaction; the overpressure in the mudstone caprock of the Upper Wuerhe Formation is attributed to undercompaction.

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