煤层气井排采时地下水响应瞬变电磁法探测研究

摘要

In order to monitor hydrogeology dynamic change effectively and discuss the migration of groundwater during drainage,transient electromagnetic method( TEM)was carried out to track and simulate the groundwater of No.3 Coalbed near PE-055 Well which was loca-ted in Panzhuang Block.The study found that dynamic changes of hydraulic connection and the storage of groundwater were caused during the process of drainage.That synchronous change between apparent resistivity and groundwater connectivity were highly coupled showed that TEM could monitor groundwater migration well. Apparent resistivity,reduced within certain range in the area of strong groundwater connec-tivity by comparison,would increase within different degree in the area of poor groundwater connectivity after drainage.The differences of reservoir between before and after drainage as well as instructions of groundwater migration direction were reflected by dynamic change of apparent resistivity,which provided new ideas and technologies for groundwater monitoring during CBM well's drainage.%为了有效地对煤层气排采期间水文地质动态变化规律进行监测，以潘庄区块为研究对象，利用瞬变电磁探测技术对3号煤层排采井P E-055附近的地下水进行探测，探讨垂直煤层气排采井地下水的运移规律。结果显示，煤层气井排采降压过程会使地下水的存储和水力联系发生动态变化，瞬变电磁探测技术能够较好监测地下水运移特征，表现为视电阻率和水力联系的同步变化具有较好的耦合性。在地下水连通性差的区域，排采后视电阻率具有升高趋势；而在地下水连通性较好区域，视电阻率明显降低；视电阻率的动态变化不仅反映储层改造前后的差异性，而且指示出煤层气井排采期间地下水的运移方向，试验结果为煤层气开发期间的地下水运移监测提供了新思路和技术。