USE OF A MULTI-OFFSET BOREHOLE-RADAR REFLECTION METHOD IN FRACTURED CRYSTALLINE BEDROCK AT MIRROR LAKE, GRAFTON COUNTY,
USE OF A MULTI-OFFSET BOREHOLE-RADAR REFLECTION METHOD IN FRACTURED CRYSTALLINE BEDROCK AT MIRROR LAKE, GRAFTON COUNTY,
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多偏移钻孔雷达反射法在格拉夫顿县镜湖断裂晶质基岩中的应用
DOI：
10.3997/2214-4609-pdb.203.1998_038
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
R. Versteeg
中科院分区：
文献类型：
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作者：
J. Lane;F. P. Haeni;R. Versteeg
在新罕布什尔州格拉夫顿县镜湖的美国地质调查局断裂岩石研究现场进行了多偏移距、单孔、钻孔雷达反射勘测。该研究旨在评估将多偏移距地震处理技术应用于裂缝岩石钻孔雷达反射勘测的效益。多炮检距反射勘探是结合盐水示踪剂注入实验进行的。在注入过程中，将氯化钠（NaCl）溶液连续泵入导液区，该导液区由悬挂在PVC套管上的特殊结构、可重复使用的PVC跨隔式封隔器隔离。在示踪剂注入之前和期间，在钻孔的PVC套管部分内收集了八个共偏移距钻孔反射剖面。发射机和接收机天线之间的偏移范围为6.4至9.9米。共炮检距数据经滤波、共距离点（CDP）道集整理、动校正（NMO）和叠加后得到零炮检距井眼CDP剖面。共偏移距和CDP剖面的对比表明，多偏移距数据采集和CDP处理：（1）提高了井眼附近反射层的分辨率;（2）降低了直接波耦合、天线振铃和系统噪声的影响;（3）提高了用于识别盐水示踪剂对透射裂缝反射影响的差分图像的清晰度。
Multi-offset, single-hole, borehole-radar reflection surveys were conducted at the U.S. Geological Survey Fractured Rock Research Site at Mirror Lake, in Grafton County, New Hampshire. The study was conducted to evaluate the benefits of applying multi-offset seismic processing techniques to borehole-radar reflection surveys in fractured rock. The multi-offset reflection surveys were conducted in conjunction with a saline tracerinjection experiment. During injection, a sodium chloride (NaCl) solution was continuously pumped into a hydraulically conductive zone that was isolated by specially constructed, reusable, PVC straddle packers suspended from PVC casing. Eight common-offset borehole reflection profiles were collected within the PVC-sleeved portion of the borehole before and during the tracer injection. The offset between the transmitter and receiver antennas ranged from 6.4 to 9.9 m (meters). The common offset data were filtered, sorted into common distance-point (CDP) gathers, normal move-out (NMO) corrected, and stacked to produce a zero-offset borehole CDP profile. Comparison of the common-offset and CDP profiles indicates that multi-offset data acquisition and CDP processing; (1) increases the resolution of reflectors near the borehole, (2) decreases the effects of direct wave coupling, antenna ringing, and system noise, and (3) improves the clarity of difference images used to identify the effects of saline tracer on reflections from transmissive fractures.