Application of Borehole Inspection Camera
Lithologic or Stratigraphic Logging
This application of a borehole camera is to view and record stratigraphy and lithology of the
accessed units. There are situations where little is known of the stratigraphy for the area in
question. While the borehole camera is less than ideal for detailed logging of a hole for
lithology, it can allow a moderate level of lithology determination. Sandstones, shales, and coals
can usually be differentiated. Separation of shales and siltstones are also at times possible.
Conglomeritic zones, nodules, and concretions can be easily observed within units with
contrasting color. Lithologic determinations work best with a color camera setup. The use of
lithologic logs for a well bore allows for more confident identification with the camera. While
the borehole camera is not a substitute for good lithologic logs, it can provide lithologic
information when the logs are incomplete or missing.
The location, orientation, rough width (aperture size), and condition (open or plugged) of
fractures can be viewed and recorded. The frequency of fractures within lithologic units, with
changes in depth, topographic location, and well location with respect to geologic structure,
mines, and other salient features are all of interest in these types of investigations. With the right equipment, fracture strike and dip can be estimated. Fracture orientation is of interest because it can yield insight as to the ground-water sources, origin of the fracture (stress relief versestectonic), and degree of fracture interconnectedness. Fracture aperture size is important in
estimating potential inflow rates or possible impacts from mine subsidence. The degree to which
a fracture is filled is important as to whether it can contribute ground water, the type of fill
material or precipitate may be indicative of the water quality yielded by that fracture, or if
biological plugging (biofouling) has occurred. Fracture strike and dip can be important in
determining the types and directions of stresses to the strata.
Well Bore and Casing Integrity
The camera can be employed to observe the general condition of the well bore in terms of
hole off-sets, zones of sloughing, precipitate build-ups, sediment accumulation, or blockages.
The length of casing used in a well, cracks or holes in the casing, casing deterioration, leaking
joints, and casing buckling can all be documented.