沁南某高阶煤井区煤层气井气、水产出差异及其控制因素

    Control mechanisms of water production and gas production divergences ofCBM wells in southern Qinshui basin

    • 摘要: 查明煤层气井气、水产出差异主控因素对于实现效益开发意义显著。基于沁水盆地南部某高煤阶煤层气井区144口井勘探与开发动态资料,分析了其气、水产出特征的差异,探讨了其形成的地质控制机制。结果表明:井区煤层气井各类产水、产气在平面上成带分布,总体上呈现高产水量-低产气特征。煤层气井产气量主要受地下水和构造样式控制,体现为:①煤层气井的产出水源主要来自压裂水、煤层水和围岩补给水,以邻近砂岩层补给水为主;②高产气井基本分布在局部复向斜的核部及其翼部上的次级背斜的翼部,中产气井主要分布在局部复向斜的宽缓翼部和次级向斜的翼部,低产气井主要分布在次级向斜的核部和研究区东部的构造高点区。建议高产水井区应控制压裂规模,保证泵长期有效工作;低产水井区要加大压裂规模,特别注意早期地下水的排采控制。

       

      Abstract: Recognizing the major controlling factors of water production and gas production divergences between CBM wells can promote the benefits in the process of CBM development.The divergences of water and gas production between CBM wells were analyzed, and then the geological control mechanisms of those divergences were further discussed, based on the dynamic data of exploration and development collected from 144 wells drilled in a high-rank coalbed methane well area in the south part of Qinshui basin.The results show that, various water wells and gas wells are belts distributed on the plane in the study area, showing the characteristics of high water yield and low gas production.Moreover, the production of CBM wells is mainly controlled by groundwater and tectonic styles, which is mainly reflected in two aspects.First, the water source of CBM wells mainly comes from fracturing water, coal seam water and surrounding rock make-up water which is mainly derived from adjacent sandstone.Second, the high-productivity wells in the study area are usually distributed over the wings of the sublevel anticline on axis and the wings of local synclinorium; the medium-productivity wells predominantly distributed over local synclinoria relief wing and secondary syncline wings; besides the low-productivity wells are primarily distributed over the axis of the secondary syncline and the high point of structures in the eastern part of the study area.Finally, it is suggested that the scale of fracturing should be controlled in well areas with high water productivity and the long term effective operation of the pump should also be guaranteed.However the scale of fracturing in well areas with low water productivity should be increased, and special attention should be paid to the control of early groundwater production.

       

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