Down-hole Test

Are techniques used to determine the physical properties and distribution of soil and rock surrounding a borehole annulus. These measurements may record naturally occurring physical phenomena, or they may use an artificial physical source, such as electrical, nuclear and acoustic, to perturb the medium and measure the response to the perturbation. From these measurements, physical properties such as density, porosity, thickness, orientation, and lithological identification of soil and rock surrounding the borehole annulus may be determined. When the source of the probe is located in the borehole and the receiver is located on the ground surface, this configuration is called a hole-to-surface configuration. In the surface-to-hole configuration, the source of the probe is located on the ground surface and the receiver is located in the borehole. When the source and the receiver are located in different boreholes, the configuration is called a hole-to-hole or cross-hole arrangement. These non-disruptive in situ physical measurements of the soil, rock and fluids are collectively known as geophysical logging. However, one must realize that information from borehole logs only comes from a limited radius around the well (no more than 1 to 3 feet) if subsurface conditions vary between wells, discrepancies may have to be qualitatively evaluated.