阜康矿区西部构造运动作用下煤储层渗透率分布特征

Distribution characteristics of coal reservoir permeability under the action of tectonic movement in western Fukang mining area

  • 摘要: 查明小范围内煤储层渗透率分布特征,可为合理井网部署、科学预测煤层气产能提供重要保障。对新疆阜康矿区西部煤岩层节理进行观测、统计和配套,获得了燕山晚期、喜马拉雅早期和喜马拉雅晚期3期构造应力场的主方向。结合构造运动反演法和煤层受力差异得出了研究区多期构造运动作用后14个块段内煤体结构及煤层的渗透率分布特征。结果表明:受多期构造运动作用影响,小范围内A2煤储层渗透率非均质性强,位于向斜核部扬起端埋深较浅处的煤层,煤体结构以碎裂-原生结构煤为主,渗透性最好;东北部风氧化带以深及南翼块段,煤层变形较弱,煤层渗透率中等;向斜核部埋深较深部位受多期构造运动影响较大,煤体变形较严重,以碎粒-糜棱煤为主,渗透性差;南部及西北部,受多期构造运动作用影响最大,煤层渗透性最差。钻井取心及渗透率实测资料验证了预测结果的准确性,此研究方法为多期构造影响下的小范围内煤层渗透率预测提供了一种思路和借鉴。

     

    Abstract: Finding out the characteristics of permeability distribution of a small-scale coal reservoir can provide important guarantee for reasonable wells pattern deployment and scientific prediction of productivity. Based on observation, statistics and assorting of the joints of coal or rock in western Fukang mining area, the main tectonic stress directions in late Yanshan period, the early and late Himalayan were obtained. The characteristics of permeability distribution of coal reservoir in 14 blocks after multiple tectonic movements were obtained using tectonic movement inversion method and coal seam stress difference analysis method. The results showed that the heterogeneity of coal reservoir permeability in small scale is obvious because of the influence of multiphase tectonic movements.The coal structure of shallow seam located in the raising end of synclinal axis is mainly primary and cataclastic, and the permeability is best in study area. In northestern oxidizing zone and south wing of the study area, the deformation of coal seam is weak, and the permeability is medium. The blocks near another end of the synclinal axis where the buried depth of coal seam is deep, were greatly influenced by the multiphase tectonic movements, coal structure is mainly mylonitic and broken, the permeability is low. The blocks in the south and the northwest of study area were affected the most greatly by multiphase tectonic movements, the permeability is the lowest. The accuracy of prediction results was verified by drilling coring and permeability data. The results can provide thinking and reference for prediction of coalbed permeability in a small area affected by multiphase tectonic movements.

     

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