煤层气井上下立体联合抽采新模式

    A New Model of Stereoscopic and Combined Coalbed Methane Drainage by Both Surface and Underground Boreholes

    • 摘要: 通过研究煤层气井上下联合抽采的理论、方法和现场试验,根据井上下煤层气抽采理论及煤炭开采后形成的“三带”(冒落带、裂隙带和弯曲下沉带)特征,提出了煤层气井上下立体联合抽采新模式:在裂隙带与弯曲下沉带之间的过渡区域采用水平井和直井对接,水平井段适当靠近回采工作面回风巷一侧;采用200 mm以上的大直径抽采管径,利用分段密封和梯度负压抽采技术,在煤炭开采不同阶段,选用不同抽采井进行煤层气抽采。该模式在煤炭回采后,时间上可实现不同区域的同步抽采,空间上可实现不同区域的立体式抽采,同时可抽采煤层顶板页岩气或致密砂岩气,实现了不同类型气体的联合抽采和“一井多用”。

       

      Abstract: Through the study of combined coalbed methane (CBM) drainage theory, method and field test by both surface and underground boreholes, according to drainage theory of CBM by both surface and underground boreholes and the characters of three zones (caving zone, fractured zone, and bending zone) above goaf, a new model for stereoscopic and combined CBM drainage by both surface and underground boreholes is proposed. The transition zone between fractured zone and bending zone should take butt joint by horizontal well and vertical well. Horizontal section is set appropriately near the return airway. Taking large diameter drainage pipe more than 200 mm and using the technology of segmented seal and graded negative pressure drainage to drain CBM choosing different drainage wells at different coal mining stages. After coal mining for this model, it can achieve synchronous drainage in different zones and stereoscopic drainage on the space. At the same time, it can drain shale gas or tight sandstone gas above the coal seam, which achieves combined gas drainage for different types of gas and "one gas well with multi applications".

       

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