基于微地震向量扫描的煤层气井天然裂缝监测

天然裂缝发育程度是影响煤层气产能的主要因素，为了准确获取沁水盆地南部A煤层气田井组的天然裂缝发育程度和分布位置，采用地面微地震向量扫描技术对区域内7口二次压裂井进行天然裂缝发育情况监测。在压裂井周围部署一定量的三分量检波器，采集压裂过程中周边储层的微地震事件，进行Semblance叠加后得到监测区内不同时刻的破裂能量切片，解释出监测区内天然裂缝发育情况。对比井组单井产能，与监测到的天然裂缝表现出良好的相关性，揭示了天然裂缝是影响煤层气单井产能的主控因素，同时表明煤层气储层非均质性强，天然裂缝呈现局部发育特征，且比较分散、面积小，常规的三维地震预测方法难以有效的识别。应用该技术能够准确地识别出煤层气储层的天然裂缝发育情况，为调整井位的部署及优选层位提供可靠的指导。 

Microseismic vector scanning-based natural fracture monitoring of the coalbed methane wells

The development degree of natural fractures is the main factor affecting coalbed methane productivity. In order to accurately obtain the distribution position of the natural fractures in the a coalbed methane field in the southern Qinshui basin, 7 refracturing wells in the area were adopted by surface microseismic vector scanning to monitor the natural fractures. A certain amount of three-component geophones were deployed around the fracturing well to collect microseismic events in the surrounding reservoir during fracturing, and after Semblance superposition, the fracture energy slices at different times in the monitoring area were obtained to explain the natural fractures in the monitoring area. Comparing the single well productivity of the well group showed a good correlation with the monitored natural fractures, revealing that natural fractures are the main controlling factor affecting single well productivity, and at the same time showed that the CBM reservoir has strong heterogeneity and natural fractures were localized. Due to the development characteristics and the relatively small scattered area, conventional 3D seismic prediction methods are difficult to identify effectively. The technology can accurately identify the development of natural fractures in coalbed methane reservoirs, and provide reliable guidance for the adjustment of well placement and measures for layer selection.