A 3-D computerised model of the southern part of Greymouth Coal Limited's
Coal Mining Licence area has recently been completed. This model, and associated
3-D CAD tools, has/is being used to optimise drillhole spacing during
exploratory data collection and as a visualisation and interpretation aid. This
model will also provide the basis for future mine planning, with the emphasis on
an optimal mine outline to maximise safety and profitable coal extraction.
Previous use of computer techniques was restricted to drillhole database entry,
storage and log production. Recently a 3-D geological/structural model was
created for the Southern Rapahoe Sector of the Greymouth Coalfield.
Geostatistical analysis of the database highlights the inadequacy of the present
drillhole spacing for preliminary mine planning. The sparsity of hard data at
depth results in a lower level of confidence in the accuracy of the 3-D model.
Nevertheless, the model and 3-D CAD techniques has been used to target and
refine ongoing resource evaluation, and provides the basis for initial reserves.
In the future the geologic model will be used as the basis for preliminary and
later (optimal) mine planning.
It is also expected to accommodate other forms of data input in seam drilling
and seismic. Development of the 3-D computer model was a first in the Greymouth
Coalfield and highlights both the use of computerised techniques for resource
evaluation and mining, and the effects of wide spaced drillhole data on model
accuracy. The computer will continue to provide the most efficient and cost
effective tool for optimal resource evaluation and mine planning as Greymouth
Coal Limited moves from feasibility/mine planning to full production. The
increased use of computer-based methods for mine planning should be seen as part
of 'The Changing Face of West Coast Mining' in line with the theme of this
Conference.