水文地质条件复杂区的煤层气开发甜点区预测

    Sweet-spot prediction about coalbed methane development in the areas with complex hydrogeological conditions

    • 摘要: 在水文地质条件复杂区,围岩富水性及向煤层补给量大小对排采时煤层内压力传播速率具有重要影响,是煤层气开发甜点区需要重点考虑的因素。以寿阳区块15#煤层为研究对象,充分考虑围岩富水性、补给量大小,结合区域地质、资源地质、可采性、可改造性,构建了包括水文地质主要参数的煤层气开发甜点区评价参数体系;应用多层次模糊综合评价法预测了煤层气开发甜点区;并与不考虑水文地质主要参数的预测结果进行了对比,通过煤层气井实际产气量对预测结果进行了验证。结果表明:研究区东北部与西南部为煤层气开发甜点区;考虑水文地质条件主要参数差异的煤层气开发甜点区预测结果更能反映客观事实;当煤层气井围岩补给水量较小时,忽略水文地质条件差异的预测结果与实际差别不大;当排采过程围岩补给量较大时,围岩补给水与煤层内的水共同竞争裂隙通道,影响煤层内水压传播速率,最终影响煤层气井的产气量。

       

      Abstract: In the area with complex hydrogeological conditions, the water abundance of surrounding rock and the amount of replenishment to the coal seam is of an important impact on the propagation speed of pressure in the coal seam during drainage, and are the key parameters to be considered in the sweet spot of coalbed methane development. Taking the 15# coal seam in Shouyang Block as the research object, the evaluation indexes system of coalbed methane development sweet spot including key hydrogeological parameters is constructed by fully considering the water abundance and recharge of surrounding rock, combining with regional geology, resource geology, recoverability and removability. The multi-level fuzzy comprehensive evaluation method is applied to predict the sweet spot of coalbed methane development. The prediction results are compared with those without considering hydrogeological conditions. The results are verified by the actual gas production of coalbed methane wells. The results show that the northeastern and southwestern parts of the study area are the sweet spot areas for CBM development. The prediction results of the sweet spot areas for CBM development considering the differences in the main parameters of hydrogeological conditions better reflect the objective facts. When the recharged water of the surrounding rock of the coal-bed gas well is small, the prediction results ignoring the differences in hydrogeological conditions are similar to the actual ones. When the surrounding rock supply is large during the drainage process, the supply water of surrounding rock and the water in the coal seam jointly compete for the fissure channel, which affects the propagation speed of water pressure in the coal seam and affects the gas production of the coalbed methane well.

       

    /

    返回文章
    返回