An appropriately developed, documented, and executed guide is essential for the proper collection and application of borehole geophysical logs.
The benefits of its use include improving the following:
Selection of logging methods and equipment,
Log quality and reliability, and
Usefulness of the log data for subsequent display and interpretation.
This guide applies to commonly used logging methods (see Table 1 and Table 2) for geotechnical investigations.
It is essential that personnel (see 7.3.3) consult up-to-date textbooks and reports on each of the logging techniques, applications, and interpretation methods. A partial list of selected publications is given at the end of this guide.
This guide is not meant to describe the specific or standard procedures for running each type of geophysical log and is limited to measurements in a single borehole.
1.1 This guide covers the documentation and general procedures necessary to plan and conduct a geophysical log program as commonly applied to geologic, engineering, ground-water, and environmental (hereafter referred to as geotechnical) investigations. It is not intended to describe the specific or standard procedures for running each type of geophysical log and is limited to measurements in a single borehole. It is anticipated that standard guides will be developed for specific methods subsequent to this guide.
1.2 Surface or shallow-depth nuclear gages for measuring water content or soil density (that is, those typically thought of as construction quality assurance devices), measurements while drilling (MWD), cone penetrometer tests, and logging for petroleum or minerals are excluded.
1.3 Borehole geophysical techniques yield direct and indirect measurements with depth of the (1) physical and chemical properties of the rock matrix and fluid around the borehole, (2) fluid contained in the borehole, and (3) construction of the borehole.