黔西小屯井田煤层气多层合采产层组合优化

    Optimization of coal-bed methane multi-layer co-production layer combination in Xiaotun Wellfield of western Guizhou Province

    • 摘要: 贵州小屯井田龙潭组煤系具有煤层数量多、煤层间距小、煤层厚度薄等特点,煤层气开发需以多层合采为主要方式;与单一厚层状煤层相比,多煤层合采易发生层间干扰,影响合采效果及资源动用程度。基于小屯井田钻孔岩性与含气性分析,识别出有利、较有利与不利3种煤岩层组合类型,考查各煤层厚度、埋深、含气量等特征,对比各煤层的煤层气资源条件,综合考虑储盖组合、含气性、渗透性、储层压力、地应力等因素,划分出Ⅰ(6煤+6煤+6煤)、Ⅱ(7煤)、Ⅲ(33煤+34煤)共3套叠置煤层气系统;在此基础上,优化合采产层组合,并确定有序开发模式为优先开发上部产层组合(6煤+6煤+6煤),其次为下部组合(33煤+34煤),最后考虑经济与时间成本确定是否单独开发7煤;确立了资源条件分析-含气系统划分-产层组合优化的多-薄煤层发育区煤层气合采层位优选思路。

       

      Abstract: The coal measures of Longtan Formation in Xiaotun well field, Guizhou Province have the characteristics of large number of coal seams, small spacing of coal seams and thin thickness of coal seams. Compared with single thick layer coal seam, multi-seam co-mining is prone to inter-layer interference, which affects co-mining effect and resource utilization degree. Based on the analysis of the lithology and gas content of the borehole in Xiaotun well field, three types of coal-rock seam combinations, namely favorable, more favorable and unfavorable, were identified, the thickness, depth of burial and gas content of each coal seam were examined, the coal-bed methane resource conditions of each coal seam were compared, the storage combination, gas content, permeability, reservoir pressure, ground stress and other factors were considered, and three sets of stacked coal-bed methane systems, I (6 upper coal + 6 middle coal + 6 lower coal), II (7 coal) and III (33 coal + 34 coal), were divided. On the basis of this, we optimize the combination of production seams, and determine the orderly development mode to give priority to the upper production seam combination (6 upper coal + 6 middle coal + 6 lower coal), followed by the lower combination (33 coal + 34 coal), and finally consider the economic and time cost to determine whether to develop 7 coal alone. The optimized idea of coal-bed methane joint mining in multi-thin seam development area is established by analyzing the resource conditions, classifying the gas-bearing system and optimizing the production layer combination.

       

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