Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (3): 633-647.doi: 10.11743/ogg20220312

• Petroleum Geology • Previous Articles     Next Articles

Prediction of shale reservoir sweet spots of the Upper Ordovician Wufeng-Longmaxi Formations in Lintanchang area, southeastern margin of Sichuan Basin

Xun Ge1,2(), Tonglou Guo3, Yongsheng Ma4, Guoli Wang3, Maowen Li2, Xiaoqun Yu5, Peirong Zhao4, Zhentao Wen5, Peng Wang5   

  1. 1.China University of Geosciences (Beijing),Beijing 100083,China
    2.Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China
    3.Southwest Oil and Gas Branch of SINOPEC,Chengdu,Sichuan 610041,China
    4.China Petroleum & Chemical Corporation,Beijing 100728,China
    5.Exploration and Development Research Institute,Southwest Oil and Gas Branch of SINOPEC,Chengdu,Sichuan 610041,China
  • Received:2021-07-26 Revised:2022-03-10 Online:2022-06-01 Published:2022-05-06

Abstract:

Well LY 1, an exploration well drilled by Sinopec Southwest Oil & Gas Company in the southeastern margin of Sichuan Basin in 2017, has proven that the Lintanchang structure was in a zone of deep water shelf facies during the Late Ordovician to Early Silurian, favorable for shale gas generation. In order to further explore the shale gas potential in this area and realize commercial breakthrough in shale gas development in the Wufeng-Longmaxi Formations, the study analyzes the structure and sedimentary features of Lintanchang area. Based on an array of geological data for tests, we select the TOC content, effective porosity and gas content of high-quality shale as the key parameters for evaluating the geological sweet spots, brittleness index and horizontal principal stress difference for determining engineering sweet spots, and dip angle, fracture influence and formation pressure for assessing preservation conditions. Seismic elastic parameters (including transverse to longitudinal velocity ratio, density and Poisson’s ratio) are obtained by pre-stack inversion. The quantitative relationship between reservoir evaluation parameters and seismic elastic parameters is established by core sample tests, as well as petrophysical analysis and lithologic characters of reservoir rocks. In addition, the AVO characteristics of lithologic information in CRP gathers are applied to predict planar changes of the shale reservoir parameters related, and eventually the favorable shale gas target in the Lintanchang structure is determined. The accurate planar mapping of shale reservoir sweet spots in structurally complex areas in the southeastern margin of the Sichuan Basin by a combination of geological-logging-geophysical methods is of guiding significance to the integrated exploration and development of shale gas therein.

Key words: sweet spot prediction, geological sweet spot, engineering sweet spot, shale reservoir, Wufeng-Long?maxi Formations, Lintanchang area, southeastern margin of Sichuan Basin

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