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Case Histories of Buried Borehole Detection
Zonge, 1996. Environmental and Engineering Geophysical Society (EEGS), presented at SAGEEP, 1996, Keystone, Colorado.
Norman R. Carlson* and Kenneth L. Zonge, Zonge Engineering and Research Organizations, Tucson, Arizona
Paper – [pdf] NanoBore_BuriedBoreholeCaseHistory
Prior to drilling injection wells for a secondary oil recovery project, our client wanted to ensure there were no old, buried oil wells within a 60-foot radius of each injection well to avoid possible contami-nation of shallow aquifers via the old wells. In addition to historical research, the oil company performed geophysical surveys to try to establish the location of the old wells, but with varying results. Zonge proposed using a very fast turn-off
transient electromagnetics (TEM) system, a NanoTEM® system, to provide both metal detection and resistivity sounding data for use in characterizing the upper 50 feet of the subsurface. This paper discusses the changes in data acquisition loop sizes and in data processing that were necessary to detect buried boreholes in several different environments.
It is sometimes difficult to determine in advance exactly which equipment or technique is best suited to a given project. Although the response of a particular target may be predictable, the local background response may be more difficult to assess until field data have actually been gathered. This becomes economically significant if the job site is relatively remote, requiring downtime and/or additional airfreight expenses when the first field results do not match expectations and a change
in equipment becomes necessary. An example of this is a series of surveys conducted in Indiana and Ohio, in which the goal was to ensure that no abandoned, buried oil wells were present within a prescribed radius of proposed injection wells. After local tests, both the physical survey layout and the data processing techniques were varied in order to detect the various possible targets in all of the different environments.