五里堠矿不同控气地质类型划分及产气特征差异

    Classification of different gas control geological types and differences in gas production characteristics in Wulihou Mine

    • 摘要: 查明煤层气井合采时控气地质类型及产气特征差异能为井位合理部署提供重要保障。以五里堠矿3+4#煤层和15#煤层为研究对象,基于前期煤层气勘探开发资料,采用克里金插值法,得出3+4#煤层和15#煤层含气量、埋深、煤厚等主要储层参数的分布特征;分析了埋深、煤厚、断层、地下水势、顶底板岩性等因素对含气量的控制作用并划分出不同控气地质类型;根据合层排采多气源产出规律,对比了不同控气地质类型下的产气特征差异,并提出了相应的开发建议。结果表明:根据3+4#煤层和15#煤层主要储层参数空间展布,将控气地质类型划分为断层主控型、埋深主控型、地下水势主控型和顶底板岩性主控型等四种类型。断层主控型,断层附近的煤层气逸散,煤层含气量低导致日产气量较低;埋深主控型,各种储层参数低导致见气时间晚、稳产气量低;地下水势主控型,水动力弱、含气量较高、导流能力强,日产气量较高;顶底板岩性主控型,当顶板为泥岩时,见气时间早,稳产气量较高。据此提出建议:埋深大于等于550 m且无断层区,优先进行煤层气开发;埋深小于550 m或距断层200 m范围内,布井应谨慎;优先选取地下水势较高的滞留区或顶板泥岩区布井。

       

      Abstract: Identifying the in gas control geological types and different gas production characteristics during coalbed methane well co-production provides important guarantees for the rational deployment of well locations. The No.3+4 and No.15 coal seams in Wulihou Mine are taken as the research object. Based on previous coalbed methane exploration and development data, the Kriging interpolation method is used to obtain the distribution characteristics of main reservoir parameters such as gas content, burial depth, and coal thickness in the No.3+4 and No.15 coal seams. The controlling effects of factors such as burial depth, coal thickness, faults, groundwater potential, and roof and floor lithology on gas content are analyzed, and different gas control geological types are classified. Based on the production law of multiple gas sources in combined layer drainage, the differences in gas production characteristics under different gas control geological types are compared, and corresponding development suggestions are proposed. The results show that the gas control geological types can be divided into four types: fault control type, burial depth control type, groundwater potential control type, and roof and floor lithology control type based on the spatial distribution of the main reservoir parameters in the No.3+4 and No.15 coal seams. The main control type of fault causes the escape of nearby coalbed methane, resulting in low coal seam gas content and daily gas production. For the buried depth control type, the gas occurrence time is late and the stable gas production is low. The main control type of groundwater potential is characterized by weak hydrodynamics, high gas content, strong flow conductivity, and high daily gas production. For the roof and floor lithology control type with a mudstone roof, the gas occurrence time is early, and stable gas production is relatively high. When the fault is within 200 m and the burial depth is less than 550 m, well layout should be cautious. If the burial depth is greater than or equal to 550 m and there are no fault areas, priority should be given to coalbed methane development. For areas with high groundwater potential, the hydrodynamic retention area or the mudstone roof area is selected as the priority area.

       

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