Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8124550 | Journal of Petroleum Science and Engineering | 2018 | 27 Pages |
Abstract
Reconstructing the evolution of paleofluid pressure in carbonate reservoirs is a challenging problem, particularly when no oil-bearing fluid inclusions are available to provide barometric constraints on the fluid system. To recover the paleofluid pressure in the Sinian Dengying Formation (Z2dn) and the Cambrian Longwangmiao Formation (Ð1l) of the central paleo-uplift of the Sichuan Basin, we conducted a comprehensive analysis combining the inclusion pressure-volume-temperature simulation, inclusions in situ Raman shifts, and basin modeling. The results showed that the evolution of the pore pressure could be divided into four stages. Prior to the end of the late Triassic, the whole central paleo-uplift was in a normal pressure state. During the Jurassic, a moderate overpressure prevailed in the dolomitic reservoirs of the Gaoshiti-Moxi area and decreased in the adjacent units. At the end of the early Cretaceous, the overpressure reached a maximum in the whole region and was strongest in the Longnüsi area, decreasing to the west. From the late Cretaceous to the present day, the central area of the basin has uplifted rapidly with the overpressure significantly decreasing. Z2dn has been restored to normal pressure during the Neogene, while Ð1l remains moderately overpressurized. Based on an analysis of the structural background and preservation conditions, the types of sedimentary facies, the preservation condition of the traps, and the differential weathering process are the primary reasons for the different pressure states in Z2dn and Ð1l during the last stages.
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Authors
Wen Liu, Nansheng Qiu, Qiuchen Xu, Yifeng Liu, Anjiang Shen, Guangwu Zhang,