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华北地区煤层气井压裂裂缝监测及其扩展规律 总被引：1，自引：0，他引：1
介绍了井温测试法、放射性同位素法、大地电位测试法和微地震测试法监测煤层水力压裂裂缝的基本原理。使用上述4种方法对华北地区施工的煤层气井压裂裂缝进行测量,得到了大量压裂井的裂缝方位和高度的监测数据。通过统计分析发现:压裂后的煤层裂缝一般都穿越其上下隔层,最大裂缝高度是压裂层厚度的6倍,裂缝长度大部分为50~90 m,裂缝形状基本以垂直裂缝为主,裂缝方向存在着随机性,扩展方向受地应力、局部地层构造和煤层割理共同作用。 相似文献
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Qifu Chen Le Li Fenglin Niu Jinrong Su Institute of Earthquake Science China Earthquake Administration Beijing China 《地震学报(英文版)》2011,(1):101-106
Repeating microearthquakes were identified along the edge of the rupture area of the 2008 MW7.9 Wenchuan earthquake.Slip rates at depths derived from seismic moments and recurrence intervals are found to be systematically larger than those observed at surface.This large deep slip rate may explain the odds about the occurrence of this unanticipated event.Our observations here suggested that seismic hazard could be underestimated if surface measurements alone are employed. 相似文献
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2002年12月25日乌恰5.8级地震序列分析及地震趋势预测 总被引：2，自引：0，他引：2
通过分析2002年12月25日乌恰5．8级地震后主震附近的地震活动特征，认为该震属孤立型地震。在地震类型判定的基础上，进一步做了以下分析工作：①乌恰—喀什区地震活动异常背景分析；②在地震活跃期内新疆境内强震主体活动区域分析；③乌恰—喀什区与阿图什—柯坪区强震活动关联性分析；④区域历史地震类型统计和震源环境分析；⑤乌恰5．8级地震和伽师—巴楚6．8级地震对区域应力场影响分析。综合分析认为，乌恰—喀什地区有明显的地震异常背景，但此次5．8、6．8级地震可能会对乌恰—喀什及周围地区的应力场产生影响，可能在一定程度上缓解该区域的应变积累，其相邻的阿图什—柯坪地区的地震活动有可能会减弱，或延缓乌恰—喀什地区的强震活动。 相似文献
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DETAILED TEMPORAL-SPATIAL DISTRIBUTION OF INDUCED EARTHQUAKES BY WATER INJECTION IN RONGCHANG,CHONGQING 
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下载免费PDF全文 Based on the seismic data collected from regional permanent stations and 6 temporal stations, we analyzed the seismic activity from October 2008 to July 2011 in Rongchang area. On the basis of HypoDD relocated results, we used Match&Locate method to detect and located the micro-earthquakes. We obtained the focal mechanism solutions of some earthquakes with ML ≥ 3.5 by using CAP method. Then we analyzed the temporal-spatial distribution of earthquakes and discussed the characteristics of micro-seismicity before the ML5.1 earthquake occurring on September 10, 2010. We totally detected 3 354 micro-earthquake events, which are nearly 5 times of the earthquakes in the seismic catalog issued by China Earthquake Networks Center. The magnitude of the detected events is mostly from ML-1 to 1, and the focal depth is from 2 to 4km. The magnitude-frequency analysis shows that the catalog completeness is obviously improved after adding the detected earthquakes, with the lowest magnitude decreasing from ML1.0 to 0.3. The earthquakes hypocenters are mainly clustered along faults or buried faults and in a dominant depth range consistent with the depth of injection wells, and also show a tendency of lateral extension from injection wells. The focal mechanism solutions of 9 earthquakes of ML ≥ 3.5 presented reverse faulting, as the same as the preexisting faults, indicating that earthquakes were surely related to reactivation of the faults. The strike, dip and rate of the causative faults separated in wide ranges, which indicates not only obvious changes in structure and strike of preexisting faults but also the effect of increasing pore pressure on the local stress field. Before the ML5.1 earthquake on September 10 of 2010, seismicity firstly showed clustering in time and covered the most part of the seismogenic fault in space. Then an obvious seismic quiescence occurred and lasted about 3 months. The phenomenon is consistent with the mechanism of creep sliding and resistance-uniformization along the fault zone, suggested on the basis of laboratory experiments, and it may be one of patterns of sub-instability along fault zone. However, such explanation needs to be further confirmed. 相似文献
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2006??8~10???????-???????????????????????????????????????????????30????????????????????2~5 km(????2???????????????????????????????????????????????????μ??????????)?? ????????4?????????????????398??????????λ????????????δ???????????鵽???40?ε??????????????????????????????????????????????????????????????о?????????????????? 相似文献