3
the art oil and gas industry visualization tools, allowing for
creation of images such as 3D wraparound perspectives as
well as dynamic images.
USE OF RSI FOR GEOMODELLING
The properties of sedimentary rocks are anisotropic, vary-
ing greatly with changes in stratigraphic position while
varying subtly with changes in lateral position. Significant
differences exist when travelling up or down within the
stratigraphy, and minimal changes when moving laterally
within the same stratigraphic unit. This principle is obvious
when you consider that within vertical millimeters, ground
conditions may change through several coal lithotypes to
sandstone – whereas a thin sandstone or tuff layer may per-
sist laterally for kilometers. The Yabby system is also sensi-
tive to variations in coal lithotypes.
This observation translates into what may be consid-
ered a stratigraphic strength profile: a characteristic signa-
ture that reflects the specific part of each seam the drill bit
is cutting in. The shape of the profile may be used to cor-
relate bit stratigraphic positions with high accuracy relative
to the rock. The correlation between the bit stratigraphic
position and strength profile is used as the key validator
for modelling the actual borehole position relative to the
stratigraphy, which is essential for geomodelling (Figure 3
and 4). The coal systems are clearly visible as low-density
(low RSI) zones. The rig monitoring system reports data
at a very high resolution, as the sampling density is effec-
tively a continuous process as drilling advances. Sensitivity
to strata changes depends on the unique properties of each
formation but can be tailored to each seam through the
software and even by modifying the drill bit to provide the
necessary detail.
The unique properties of each rig and coal seam are
modelled, and the possibility exists to tailor drill bit designs
to magnify variance in stratigraphy, providing greater con-
trast and improving results accordingly.
APPLICATIONS FOR MANAGEMENT OF
METHANE DRAINAGE
Globally, knowledge of a coal seam’s gas reservoir proper-
ties is typically derived from sporadic, high resolution, low
Figure 1. Schematic showing how the Yabby GeoSensing system provides information to improve
geological models
Figure 2. Visualization example using Yabby underground
directional drilling data, superimposed on 3-D coal seam
model showing interpreted structures. Relative hardness of
the formation is represented by the hot/cold colors along the
borehole path
the art oil and gas industry visualization tools, allowing for
creation of images such as 3D wraparound perspectives as
well as dynamic images.
USE OF RSI FOR GEOMODELLING
The properties of sedimentary rocks are anisotropic, vary-
ing greatly with changes in stratigraphic position while
varying subtly with changes in lateral position. Significant
differences exist when travelling up or down within the
stratigraphy, and minimal changes when moving laterally
within the same stratigraphic unit. This principle is obvious
when you consider that within vertical millimeters, ground
conditions may change through several coal lithotypes to
sandstone – whereas a thin sandstone or tuff layer may per-
sist laterally for kilometers. The Yabby system is also sensi-
tive to variations in coal lithotypes.
This observation translates into what may be consid-
ered a stratigraphic strength profile: a characteristic signa-
ture that reflects the specific part of each seam the drill bit
is cutting in. The shape of the profile may be used to cor-
relate bit stratigraphic positions with high accuracy relative
to the rock. The correlation between the bit stratigraphic
position and strength profile is used as the key validator
for modelling the actual borehole position relative to the
stratigraphy, which is essential for geomodelling (Figure 3
and 4). The coal systems are clearly visible as low-density
(low RSI) zones. The rig monitoring system reports data
at a very high resolution, as the sampling density is effec-
tively a continuous process as drilling advances. Sensitivity
to strata changes depends on the unique properties of each
formation but can be tailored to each seam through the
software and even by modifying the drill bit to provide the
necessary detail.
The unique properties of each rig and coal seam are
modelled, and the possibility exists to tailor drill bit designs
to magnify variance in stratigraphy, providing greater con-
trast and improving results accordingly.
APPLICATIONS FOR MANAGEMENT OF
METHANE DRAINAGE
Globally, knowledge of a coal seam’s gas reservoir proper-
ties is typically derived from sporadic, high resolution, low
Figure 1. Schematic showing how the Yabby GeoSensing system provides information to improve
geological models
Figure 2. Visualization example using Yabby underground
directional drilling data, superimposed on 3-D coal seam
model showing interpreted structures. Relative hardness of
the formation is represented by the hot/cold colors along the
borehole path