ZHANG J M, ZHAO D F, GUO Y H,et al.Multiple parameter evaluation of shale gas reservoirs based on a fuzzy entropy weight and coefficient variation method：A case of well F-2 in Wulong Area，Sichuan Basin[J].Journal of Henan Polytechnic University(Natural Science) ,2024,43(6):57-68.

Received:2022/10/06

Revised:2022/12/15

Online:2024-09-24

Multiple parameter evaluation of shale gas reservoirs based on a fuzzy entropy weight and

coefficient variation method：A case of well F-2 in Wulong Area，Sichuan Basin

ZHANG Jiaming1,2, ZHAO Difei3, GUO Yinghai1,2, ZHANG Qing3, GUAN Xin4, JIAO Weiwei5, WANG Shengxiu6

1.School of Resources and Geosciences，China University of Mining and Technology，Xuzhou  221116，Jiangsu，China；2.Key Laboratory of Coalbed Methane Resources & Reservoir Formation Process，Ministry of Education，Xuzhou  221008，Jiangsu，China；3.Artificial Intelligence Research Institute，China University of Mining and Technology，Xuzhou  221000，Jiangsu，China；4.School of Safety Engineering，China University of Mining and Technology，Xuzhou  221116，Jiangsu，China；5.School of Architectural Engineering，Chongqing Industry Polytechnic Institute，Chongqing  401120，China；6.Shale Gas Branch，Chongqing Institute of Geology and Mineral Resources，Chongqing  401120，China

Abstract:Due to the complex geological conditions，insufficient economic costs and mining technology and other factors，it is necessary to evaluate the quality of shale reservoir before exploiting the shale gas.  Objectives In order to explore the key parameters that affect the shale reservoir quality，  Methods taking clay minerals，brittleness index，TOC，porosity and gas content as evaluation indexes，the entropy weight method and variation coefficient method were used to calculate the combination weight，and the fuzzy theory combined with TOPSIS method and RSR method was used to evaluate the reservoir quality of Wufeng Formation-Long1₁ subsection（Long ，Long ，Long ，Long ） of well F-2.  Results The results showed the shale mineral components of Wufeng Formation-Long1₁ subsection of well F-2 in Wulong Area were mainly quartz and clay minerals，and the vertical heterogeneity of material components and physical properties was significant.The average content of quartz in Wufeng Formation-Long  subsection was the highest.Its average content of TOC was more than 4%，and its porosity was greater than 4%.A relatively downward trend of these elements had been shown in the upward direction，and they dropped to the lowest in Long subsection.The gas content was relatively high in Wufeng Formation-Long  subsection，and also showed a downward trend in the upward direction，and in Long subsection the gas content decreased to less than 2%.The Long  subsection with relatively deep water body and high static degree formed the best material composition ratio and the highest organic matter content during the sedimentation period.Its bedding was well developed and rich in biogenic silica，and its organic pores were developed to a high degree.Therefore，its reservoir quality was optimal.The sedimentary environment of Long  subsection and Long subsection was relatively shallow.The input of terrigenous detritus to these two sections was increased，and the reservoir quality was inferior.In the sedimentary period of Wufeng Formation，the reservoir was developed in a detention basin environment，and the heterogeneity of some intervals was relatively stronger due to the influence of terrigenous input，and the overall quality was relatively lower.The reservoir quality of Long  subsection was the worst.  Conclusions Therefore，it was recommended to give priority to the exploitation of Long  subsection，and the exploitation of Long  subsection，Long  subsection and other parts of the Wufeng Formation was the second choice.

Key words:shale gas;reservoir evaluation;Wufeng-Longmaxi Formation;fuzzy theory;fuzzy entropy weight  and coefficient variation method