构造应力控制下的煤层气运移规律分析

    Analysis on Coalbed Methane Migration Under the Control of Tectonic Stress

    • 摘要: 针对地质构造复合控气模式,选取向斜和断层面受力状态与封闭能力为研究目标。研究发现,断面的应力状态反映了局部应力集中程度,断层对于缓解向斜的构造应力作用显著,而向斜翼部的断层位置控制了煤层气运移规律的差异程度。通过平煤十三矿部分煤层气井的产量监测发现,密闭构造条件下(If>4.5),储层压力梯度大,局部储层渗透率陡然变低,但煤层气排采产量较高;沿主应力方向裂隙发育区带,储层渗透率变化较大,其运移能力受气体赋存状态制约;构造联合作用下的储层封闭能力决定该区域煤层气运移规律。

       

      Abstract: For the models of geological structure compound controlling gas action, taking the stress state and sealing ability of syncline and fault plane as research object, the study found that the stress state of a fault plane reflected concentrative degree of local stress, the fault plays significant role in buffering tectonic stress of a syncline, however, the position of the fault in a syncline's wing determined the difference of gas occurrence and migration law of coalbed methane (CBM). Through the production data from some CBM wells in Pingdingshan No.13 Mine, the paper analyzed the control models and found that it's a low permeability and a high pressure gradient in sealed structure reservoir (If>4.5), while it had high drainage production for a well nearby structure; the reservoir's permeability was high in fracture zone along principal stress direction, and its migration ability was controlled by occurrence state of CBM in reservoir; the migration law of CBM was determined by sealing ability of reservoir considering the combined effect of geological structure.

       

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