8
increased the visibility of geologic features, including the
fracture. Furthermore, water enhances the color contrast of
rocks and helps to accentuate the differences between adja-
cent rock types, favorable for identifying lithology changes
on borehole walls.
First, water can darken the surface of rocks. The freshly
washed borehole has a darker color than the freshly drilled
one and the washed and dried one. However, this effect
varies with rock type. Different lithologies, like sandstone,
shale, and coal, may react differently to water. Sandstone
and shale will darken to different extents when wet and
makes it easier to distinguish between layers with differ-
ent compositions. If the rocks have different mineral con-
tents, water will highlight these differences by deepening
the color contrast. Organic-rich shale might become very
dark or black when wet, and iron-rich layers may show
more reddish or brownish tones. Wet coal seams will stand
out due to the very dark, glossy appearance. Specifically for
laminated shale, as shown in Figure 7 (b), water highlights
subtle differences between fine layers by making lamination
or thin bedding more pronounced.
In addition, water accentuates the differences in grain
size and porosity of adjacent lithologies. Sandstone has
coarser grains and absorbs water differently compared to
fine-grained rocks, like shale or siltstone. Fine-grained
shales will develop a smoother, more uniform darkening
when wet. Coarser sandstones may appear rougher and
absorb water more deeply, making transitions to finer-
grained rocks more evident.
Finally, different rocks have varying porosities and per-
meabilities, affecting how they absorb water. Sandstones
have higher porosity and will absorb water quickly, poten-
tially remaining wet for a longer time than the rocks with
lower porosity, like shale or siltstone. Shales and siltstones
cannot absorb as much water and may dry out more quickly.
As shown at the bottom marked location in Figure 9, there
is one segment in the washed and dried borehole with the
presence of water on the wall. The video was recorded 12
days after washing and all the other sections are dried.
Although it is difficult to identify the lithology or lithol-
ogy change from the borehole images, the presence of water
after 12 days indicates that, at least, the porosity for this
section is higher than that of the other dried sections.
In summary, water can significantly aid in identifying
lithological changes in borehole surfaces by enhancing color
contrasts, highlighting bedding planes and fractures, and
accentuating differences in porosity and grain size. Wetting
makes transitions between different rock types, such as
between sandstone, shale, siltstone, and coal, more visible
by enhancing textural and color contrasts, and revealing
natural features like cleats, veins, and fractures.
CONCLUSIONS
In this study, the influence of borehole conditions on pan-
oramic borehole images was studied by processing the
borehole videos recorded under different conditions for the
same borehole. The results show that the image stitching
process can be affected by the borescope movement and
borehole condition, and thus, the analysis of the influence
of borehole condition was combined with the borescope
movement. The borehole videos recorded in the freshly
drilled borehole and the washed and dried borehole were
successfully stitching as panoramic borehole images, while
the stitching failed 13 times when processing the video
recorded within the freshly washed borehole. The results
show that the stitching failures all occurred with relatively
large vertical and/or horizontal movements with water on
the borehole wall. The combination of these two conditions
can have significant adverse effects on the image stitching
process.
Figure 9. Generated panoramic borehole images under three
different conditions with enlarged views for geologic features
increased the visibility of geologic features, including the
fracture. Furthermore, water enhances the color contrast of
rocks and helps to accentuate the differences between adja-
cent rock types, favorable for identifying lithology changes
on borehole walls.
First, water can darken the surface of rocks. The freshly
washed borehole has a darker color than the freshly drilled
one and the washed and dried one. However, this effect
varies with rock type. Different lithologies, like sandstone,
shale, and coal, may react differently to water. Sandstone
and shale will darken to different extents when wet and
makes it easier to distinguish between layers with differ-
ent compositions. If the rocks have different mineral con-
tents, water will highlight these differences by deepening
the color contrast. Organic-rich shale might become very
dark or black when wet, and iron-rich layers may show
more reddish or brownish tones. Wet coal seams will stand
out due to the very dark, glossy appearance. Specifically for
laminated shale, as shown in Figure 7 (b), water highlights
subtle differences between fine layers by making lamination
or thin bedding more pronounced.
In addition, water accentuates the differences in grain
size and porosity of adjacent lithologies. Sandstone has
coarser grains and absorbs water differently compared to
fine-grained rocks, like shale or siltstone. Fine-grained
shales will develop a smoother, more uniform darkening
when wet. Coarser sandstones may appear rougher and
absorb water more deeply, making transitions to finer-
grained rocks more evident.
Finally, different rocks have varying porosities and per-
meabilities, affecting how they absorb water. Sandstones
have higher porosity and will absorb water quickly, poten-
tially remaining wet for a longer time than the rocks with
lower porosity, like shale or siltstone. Shales and siltstones
cannot absorb as much water and may dry out more quickly.
As shown at the bottom marked location in Figure 9, there
is one segment in the washed and dried borehole with the
presence of water on the wall. The video was recorded 12
days after washing and all the other sections are dried.
Although it is difficult to identify the lithology or lithol-
ogy change from the borehole images, the presence of water
after 12 days indicates that, at least, the porosity for this
section is higher than that of the other dried sections.
In summary, water can significantly aid in identifying
lithological changes in borehole surfaces by enhancing color
contrasts, highlighting bedding planes and fractures, and
accentuating differences in porosity and grain size. Wetting
makes transitions between different rock types, such as
between sandstone, shale, siltstone, and coal, more visible
by enhancing textural and color contrasts, and revealing
natural features like cleats, veins, and fractures.
CONCLUSIONS
In this study, the influence of borehole conditions on pan-
oramic borehole images was studied by processing the
borehole videos recorded under different conditions for the
same borehole. The results show that the image stitching
process can be affected by the borescope movement and
borehole condition, and thus, the analysis of the influence
of borehole condition was combined with the borescope
movement. The borehole videos recorded in the freshly
drilled borehole and the washed and dried borehole were
successfully stitching as panoramic borehole images, while
the stitching failed 13 times when processing the video
recorded within the freshly washed borehole. The results
show that the stitching failures all occurred with relatively
large vertical and/or horizontal movements with water on
the borehole wall. The combination of these two conditions
can have significant adverse effects on the image stitching
process.
Figure 9. Generated panoramic borehole images under three
different conditions with enlarged views for geologic features