Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (2): 509-521.doi: 10.11743/ogg20210219

• Petroleum Geology • Previous Articles     Next Articles

Controlling effects of syn-depositional reverse fault associated folds on the deposition in alluvial fan sheet glutenites and braided channels: A case study of the Triassic Karamay Formation in Huwan area, northwestern margin of Junggar Basin

Qinyu Xia1,2(), Shenghe Wu2, Wenjie Feng3, Zhongbao Liu3   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
    2. College of Geosciences, China University of Petroleum (Beijing), Beijing 102249, China
    3. School of Geosciences, Yangtze University, Wuhan, Hubei 430100, China
  • Received:2019-02-25 Online:2021-04-28 Published:2021-04-21

Abstract:

This study applied the flume simulation to the deposition of alluvial fan controlled by syn-depositional reverse fault associated folds and conducted a sectional observation on the distribution of sheet glutenites and braided channels in the fan after the simulation.The result was then used as a guidance in an identification of sheet glutenites in the lower Triassic Karamay Formation and braided channels in upper Karamay Formation of the Huwan area in northwestern margin of Junggar Basin that comprehensively took into consideration the core, outcrop, infill well network and seismic data as well as information gained through studies on the intensity of syn-depositional reverse fault associated folds in the area.Individual subsurface single configured unit was also dissected and investigated according to quantitative outcrop scale and well log marks to study the process, scale, direction and superimposing styles of the deposition of sheet glutenites and braided channels under the control of the folds.The results show that sheet glutenites are preferentially deposited in locations near provenance and with underdeveloped folds.They are mostly large in size—at least 1 000 m wide and 1 400 m on average.They usually migrate from main stream pathway to both sides and are less laterally superimposed.In locations at the edge of folds or where folds are less active, the sheet glutenties and braided channels would flow around the folds and migrate from an obliquely crossing provenance way to a direction parallel to the provenance way.With the smallest ones of only 450 m in width and an average of 1000 m, the glutenites in these locations are small in size and laterally superimposed.The braided channels in these locations are interlaced or banded and about 150 m to 350 m wide and 1.5 m to 8.1 m thick.In locations where the folds are active, sheet glutenite is not observed and braided channels are narrow isolated bands of about 80 m to 120 m wide and 1 m to 4 m thick.

Key words: sheet glutenite, alluvial fan facies, braided channel, Triassic, sedimentary architecture, syn-depositional reverse fault associated fold, northwestern margin of Junggar Basin

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