Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (2): 370-390.doi: 10.11743/ogg20210209

• Petroleum Geology • Previous Articles     Next Articles

Syncline development and tight sandstone gas accumulation model in Shigouyi area at western margin of Ordos Basin

Dengfa He1(), Fangyuan Sun1, Yonghe Zhai1, Hongping Bao2, Jinghui Ma1, Baize Kai1   

  1. 1. School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Petroleum Exploration and Development Research Institute under Changqing Oilfield Branch, PetroChina, Xi'an, Shaanxi 710018, China
  • Received:2020-05-16 Online:2021-04-28 Published:2021-04-21

Abstract:

Syncline as a basic type of folds is one of the main structures hosting coal-bed gas, tight gas, shale gas, salt and gypsum, and uranium, etc.The study on the formation mechanism of syncline means significantly to analyzing the tectonic evolution and resource distribution in fold zones.The deep structure and forming mechanism of the syncline in Shigouyi area at the western margin of Ordos Basin were analyzed based on recent high-resolution seismic profiles and deep borehole data.It is shown that the syncline was formed during the end of the Middle Jurassic and Late Jurassic and located at the transitional area between the northern and central segments of the western foreland margin of the Ordos Basin.Based upon the large-scale imbricate thrust system detached along the coal measures of the Upper Carboniferous Yanghugou Formation and the Lower Permian Shaanxi Formation, the syncline is the upper folding system of a large-scale tectonic wedge underthrusted by underlying earlier domino-style normal fault blocks.A positive reverse fault named Hui'anpu in the area can be used to define the tectonic and depositional domains.The Upper Carboniferous and Lower Permian tight sandstones in the syncline and adjacent areas were the trinity of source rocks, reservoirs and cap-rocks for gas during the Early Cretaceous.The syncline, coupled with the fact that it was formed prior to gas pooling peak period, is therefore considered rich in gas and a good exploration target.

Key words: tight sandstone gas, tectonic wedge, folding style, Shigouyi syncline, western margin of Ordos Basin

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