China Petroleum Exploration ›› 2018, Vol. 23 ›› Issue (4): 30-38.DOI: 10.3969/j.issn.1672-7703.2018.04.004

• PETROLEUM GEOLOGY • Previous Articles     Next Articles

Evaluation on exploration potentials of Lower Jurassic reservoirs in eastern Sichuan Basin

Zou Juan1, Jin Tao1, Li Xuesong2, Wei Tengqiang1, Guo Ruiying1, Bai Rong1   

  1. 1 Research Institute of Exploration and Development, PetroChina Southwest Oil & Gas Field Company;
    2 Research Institute of Exploration and Development, PetroChina Xinjiang Oilfield Company
  • Received:2017-04-25 Revised:2018-05-20 Online:2018-07-15 Published:2018-07-11
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Abstract: Many wells in eastern Sichuan Basin delivered good oil and gas shows in the Jurassic formation, but they have not been given enough attention due to the fact that the Jurassic structural highs were almost eroded. Therefore, identifying the exploration potential is of great significance in guiding the exploration of the Jurassic reservoirs in the eastern Sichuan Basin. The conditions of source rocks, reservoirs, structures and preservation are analyzed, and the results show that the source rocks in the Lower Jurassic Lianggaoshan Formation and Da'anzhai Member are relatively thick, the effective source rock in the Lianggaoshan Formation is 5.6-35.8 m thick, and that in the Da'anzhai Member is 2.7-58.0 m thick; the TOC of the Lianggaoshan Formation is 0.15%-3.86%, and that of the Da'anzhai Member is 0.15%-2.76%, both about 1.00% on average; the high organic matter abundance indicates hydrocarbon generating is at a peak period there and the resources are rich; sandstone and limestone reservoirs are of extremely low porosity and permeability, but favorable reservoirs in beach bars and shelly beaches are distributed over a large area in the central and northern parts of the eastern Sichuan Basin; the interbedded source-reservoir assemblage is favorable for short-distance migration and accumulation of hydrocarbon; the well preserved Jurassic formation in the wide and gentle syncline of the fold belt provides good preservation conditions. All these points reflect that the Lower Jurassic Lianggaoshan Formation and Da'anzhai Member in the eastern Sichuan Basin have good exploration potentials, especially the Xuanhan-Kaijiang-Liangping-Wanzhou region has the best hydrocarbon accumulation conditions in the central and northern parts. Finally, about 5000 km2 in the Lianggaoshan Formation and about 3000 km2 in the Da'anzhai Member are proposed for favorable areas for future exploration.

 

Key words: eastern Sichuan Basin, Lower Jurassic, Lianggaoshan Formation, Da'anzhai Member, source rock, reservoir, source-reservoir assemblage, exploration potential

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