西南石油大学学报(自然科学版)

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Seismic Geomorphology of Channel Belts of the 5th Interval,Xujiahe Formation,Upper Triassic in Central Sichuan Basin,China

Zhou Chuanmin1,2, Song Lihong3, Liu Qingsong4, Luo Zhong1,2, Gao Zhiyong1,2   

  1. 1. State Key Laboratory of Enhanced Oil Recovery,Haidian,Beijing 100083,China;2. Research Institute of Petroleum Exploration & Development,PetroChina,Haidian,Beijing 100083,China;3. Kunming Sinotech Minerals Exploration Co. Ltd.,Kunming,Yunnan 650024,China;4. Exploration Division of Southwest Oil and Gas Field Company,PetroChina,Chengdu,Sichuan 610041,China
  • Online:2014-08-01 Published:2014-08-01

Abstract:

In fluvial-delta depositional environment,the main reservoir is thin bed channel sandstone which is very important in China′s onshore lithological reservoirs. In this study,the channel geomorphology of the 5th interval of Xujiahe Formation (T3x5)has been mapped using seismic sedimentology. The result shows that channel geomorphology of T3x5 is similar with modern channel belts in channel-flood plains. By seismic geomorphology technology,channel belts,main channels,distributary channels and abandoned channels can be distinguished in striatal slices. Main channels which have very clear morphology are characterized by width <1.1 km and length on the order of tens of kilometers. Distributary channels or abandoned channels with blurred morphology are characterized by width <100.0 m and length <5.0 km. Main channels are relatively immobile,so they are easy to preserve after deposition. In contrast,distributary channels which are apt to cause avulsions are vulnerable to rework by erosion. In channel belts,superimposed channel bars are favorable lithological reservoirs,which is characterized by width up to 5 km and thickness up to 37 m. This study shows that seismic sedimentology is a useful approach to map thin bed sandstone in the lithological reservoirs.

Key words: Sichuan Basin, seismic sedimentology, seismic geomorphology, Xujiahe Formation, channel belt