基于三端元图版的复杂构造区煤体结构识别方法

    Coal structure identification method based on three-terminal tuple chart in complex structure area

    • 摘要: 贵州省煤层气资源量十分丰富,且主要赋存在二叠系上统龙潭组煤层中。不同的煤体结构是煤储层的渗透率、孔隙度、可压性、含气量等参数的重要影响因素,同时与后期的压裂施工选层、产气量大小密切相关,因此随着贵州省省内煤层气勘探开发的不断深入,煤体结构的定量判识越来越受到重视。为解决常规排采井煤体结构识别困难问题,根据不同煤体结构的测井响应特征,提出基于三端元图版的煤体结构定量识别方法,建立了研究区煤体结构三端元识别图版。研究结果表明:随着破碎程度的增强,原生结构煤、碎裂煤、构造煤总体表现为补偿密度、电阻率依次减小,补偿声波、补偿中子、自然伽马等逐渐增大;当选取补偿密度、电阻率、自然伽马测井曲线数据作为三端元图版的3个端点时,不同煤体结构类型在三端元图版上有很好地区分。与岩心识别和成像测井识别结果对比分析表明,三端元图版可有效提高煤体结构识别的准确性。

       

      Abstract: The coalbed methane resources in Guizhou Province are extremely abundant and are mainly present in the coal seams of Longtan Formation of the Upper Permian. Different coal body structures are significant influencing factors for parameters such as the permeability, porosity, compressibility, and gas content of coal reservoirs. Meanwhile, they are closely related to the layer selection for fracturing operations and the magnitude of gas production in the later stage. Therefore, as the continuously deepening exploration and development of coalbed methane in Guizhou Province, the quantitative identification of coal body structures has received increasing attention. To address the difficulty in identifying coal body structures in conventional drainage and production wells, based on the logging response characteristics of different coal body structures, this study proposes a quantitative identification method of coal body structure based on three-terminal tuple chart and establishes a three-terminal tuple identification chart for the coal body structure in the study area. The research results indicate that with the intensification of the fragmentation degree, the primary structural coal, fractured coal, and tectonic coal generally exhibit a sequential decrease in compensated density and resistivity, and a gradual increase in compensated acoustic wave, compensated neutron, and natural gamma, etc. When the logging curve data of compensated density, resistivity, and natural gamma are selected as the three-terminal points of the three-terminal tuple chart, different coal body structure types are well distinguished on the three-terminal tuple chart. Moreover, comparing with the identification results of core and imaging logging, it is demonstrated that the three-terminal tuple chart can effectively enhance the accuracy of coal body structure identification.

       

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