Oil & Gas Geology ›› 2018, Vol. 39 ›› Issue (2): 300-308.doi: 10.11743/ogg20180209

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Lithologic gas reservoir formation and exploration potential of the Xujiahe Formation in gently structured zones,southern Sichuan Basin

Jin Hui1, Yang Wei1, Xia Jiwen2, Ma Yanliang2, Shi Zhensheng1, Shen Juehong1   

  1. 1. Department of Natural Gas Geology, Research Institute of Petroleum Exploration and Development, PetroChina, Langfang, Hebei 065007, China;
    2. Shunan Gasfield, Southwest Oil & Gasfield Company, PetroChina, Luzhou, Sichuan 646000, China
  • Received:2017-04-20 Revised:2017-12-12 Online:2018-04-28 Published:2018-05-16

Abstract: There is no significant breakthrough in the exploration and development of the Xujiahe Formation in Shunan area in recent years compared with that of lithologic gas reservoir of the Xujiahe Formation in the central Sichuan Basin.Thus the lithologic gas reservoir forming conditions and exploration potential of the Xujiahe Formation in gently structured zones of Shunan area have always been the focus of attention.With the integrated analysis of outcrop,core and logging data,and the investigation of various accumulating conditions and major controlling factors,such as tectonic setting,sedimentary sandbody development,source rock presence,reservoir characteristics and etc.of the Xujiiahe Formation in this area,we believe that:(1) a large area of flat laying strata in the tectonically quiescent area is favorable for forming lithologic gas reservoirs;(2) the source rocks capable of large area hydrocarbon generation are distributed widely in the 1st,3rd,5th member and the 2nd submember of the 6th member of the Xujiahe Formation,providing the gas source for lithologic accumulation;(3) the 2nd,4th member and the 1st,6th submember of the 6th member of the Xujiahe Formation in the large-scale open flow lacustrine basin mainly are sandstones that are widespread and present in multiple zones,favorable for reservoir formation;(4) source beds and reservoirs interbeddedly deposit,resulting in similar accumulating features to the Xujiahe Formations in the central Sichuan Basin,i.e.large area continuous source kitchen hydrocarbon supply and efficient near-source charge.We believe that the Xujiahe Formation in the Shunan area has the conditions favorable for lithologic gas accumulating and may have formed a large-scale gas accumulation area.The understanding provides the geological basis for the exploration deployment of the Xujiahe Formation in tectonically quiescent zones,and indicates that the gently structured area between the low structures will be a focus for further exploration.

Key words: low gentle structure, accumulating condition, lithologic gas reservoir, Xujiahe Formation, Shunan area, Sichuan Basin

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