Oil & Gas Geology ›› 2018, Vol. 39 ›› Issue (1): 175-182,191.doi: 10.11743/ogg20180117

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Sedimentary characteristics and spatial distribution of coarse clastic rocks of fan delta in Changdi fault zone in Gubei sub-sag, Jiyang Depression

Qiu Longwei1, Jia Jicheng1, Ma Lichi2, Yang Yongqiang1, Sun Chao2, Xin Ye2, Wang Xin3, Yang Shengchao4   

  1. 1. School of Geosciences, China University of Petroleum, Qingdao, Shandong 266580, China;
    2. Research Institute of Geological Sciences, Shengli Oilfield Company, SINOPEC, Dongying, Shandong 257015, China;
    3. First Oil Production Plant of Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China;
    4. Nanjing University, Nanjing, Jiangsu 210023, China
  • Received:2016-01-15 Revised:2018-01-04 Online:2018-02-28 Published:2018-03-12

Abstract: Fan delta coarse clastic rocks on steep slopes of faulted lacustrine basins have large variability in spatial distribution due to the joint control of various geological factors.Various data including core, log and seismic data are integra-ted to investigate the spatial distribution characteristics and the main controlling factors on formation of the fan delta coarse clastic rocks in the 2nd to the Upper 4th Member of the Eocene Shahejie Formation on the periphery of Changdi fault zone in Gubei sub-sag.The study results show that the development of fan delta coarse clastic rocks are controlled by the intensity of fault activity, change of lake level and sediment supply.The contributions of each influential factor are different in different areas, resulting in the differences of distribution of these fan delta coarse clastic rocks.In the northern part of Changdi fault zone, fault activities are strong and sediment supply is sufficient, thus the fan delta deposits are large in scale and are characterized by vertical aggradation of multiple stages on sectional view.In addition, large slump turbidite fans are common in fan front.On the contrary, in the southern part of the fault zone, faulting is relatively weak and sediment supply is insufficient, thus the fans are small in scale and show a superimposition pattern of early retrogradation and late progradation.Owing to the alternative activity of secondary faults, the fan delta coarse clastic rocks are characterized by wedge-shaped superimposition of multiple stages in the direction of perpendicular to provenance.In general, the distribution of oil and gas in the study area are controlled by favorable sedimentary facies zones, lateral pinch out of the fans and sealing of top mudstone.

Key words: coarse clastic rock, secondary fault, Shahejie Formation, Zhaihua sag, Jiyang Depression

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