井间地震层析成像技术在煤层气压裂监测的应用

Application of Cross-borehole Seismic Tomography during CBM Fracturing Monitoring

大1-5井和大1-1井是沧县境内的两口煤层气井,为提高产能,增大气体解吸速率,对其进行了压裂施工。为测定压裂效果,使用DST-3井中声波探测系,对大1-1与大1-5两口煤层气井在压裂前后分别进行了地震层析成像测试,层析成像结果显示,压裂后煤层波速有明显下降,且在横向上变化均匀,表示压裂液扩散带基本连通,裂缝发育,压裂效果明显。为了验证层析成像的结果,将煤层气井的测井解释结果与层析成像结果做了对比,结果较吻合。

The DA1-5 and DA1-1 are two CBM wells located in Cangxian County have carried out fracturing for production capacity and gas desorption rate boosting. To take measure of fissuring effectiveness, the DST-3 borehole sonic detector system was used, carried out seismic tomographic testing before and after fracturing of the two CBM wells, the results demonstrated that the wave velocity in coal seam has declined evidently, and evenly changing transversally, showing the fracturing liquid diffusion zones are basically connected, fractures developed, thus the better fracturing effectiveness obtained. For effect justifying, contrasted coal seam well logging results with tomographic results, and they are tally with each other.