John Jansen, Ph.D., Aquifer Science & Technology
Geophysical logging tools have gotten smaller and more sophisticated over the last 20 years. This has significantly increased the quality and types of down hole measurements that can be obtained for water resource investigations. In the past, logging studies for water resource projects were typically limited to a few simple methods that measured physical properties, such as spontaneous potential and bulk resistivity, that were indirectly related to the parameters of interest, such as formation yield and water quality. Significant inferences based on broad assumptions were needed to interpret the data. This limited the information that could be obtained, especially in aquifers where little previous work had been done. New logging tools can now make direct measurements of many physical properties of direct interest to well construction or water resource evaluations. These properties include; interval water production, formation water quality, differential head, borehole condition, and the condition of casing and grout. With the right logs interval transmissivity, interval hydraulic conductivity, and interval head can be measured. These properties are more directly related to the objectives of most water resource investigations. When properly integrated with traditional logging methods, a much more complete picture of the aquifer and borehole environment can be provided.
This presentation focuses on several case histories that illustrate the use of these methods to solve a variety of practical problems. Specific examples will be presented illustrating the identification of; major water producing intervals, major confining units, zones of poor water quality, and the integrity of casing and grout. The presentation is meant to be a companion presentation to James LoCoco’s presentation on advances in geophysical logging methods and equipment.
2007 NGWA Ground Water Expo and Annual Meeting
