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By Hugo Melo

Exploration and GIS

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SRK is often asked to provide geological expertise in the early stages of a coal exploration program. In identifying new opportunities and areas for exploration, typically SRK recommends that the first stage in any greenfields exploration should involve a collation of all relevant open-file data, integrating it into a GIS-based work platform or equivalent, followed by an assessment of the data and the construction of a preliminary geological model.

To better understand the geology of a prospect area and develop new, at times high risk, exploration targets, particularly in an area of extensive activity, it is useful (arguably critical) to place the area in its regional geological context. To do this effectively, we recommend that data collation and interpretation extend more broadly than the confines of the exploration tenements themselves.
Collecting data not only from historical coal exploration (borehole data, seismic line data, geological maps) and the geophysics of the region (magnetics & gravity, etc) but also from waterbore or minerals exploration work can be valuable.

The model to be developed may need to consider the depth of economic cover, depth to the containing basement in addition to a preliminary structural framework. The model may also need to identify likely active basement or early forming basin faults, if the targeted coal-bearing sequences occur early in a basin’s depositional history.

In most cases, a robust sub-regional geological model can be constructed from regional geophysical and coal geological datasets of variable detail and reliability. The model and supporting datasets then provide:

• a context for placing and assessing a lease’s exploration potential
• a solid platform for exploration to build a lease-scale structural model and reduce geological uncertainty

By creating a single work platform of information, new data can be evaluated rapidly against the existing model and datasets and interpretations can be refined. Where this approach is adopted, ongoing exploration will likely demonstrate noticeable benefits including more cost effective and efficient exploration targeting and prospectivity ranking of target areas.

While the approach can be applied at any stage of an exploration program, it can help avoid wasted exploration focus and expenditure if adopted in the early stages of lease exploration work.

SRK has recently helped Excel Coal (now Peabody Energy Australia) and Conarco in their joint-venture to construct an accessible GIS platform and geological model for the area containing their coal exploration tenements along the margins of the Permian-aged Bowen Basin, in Central Queensland, Australia. The GIS and geological model were constructed soon after acquiring the leases, before field visits and the start of exploratory drilling. Target coal-bearing sequences included early Permian depo-centres, which involve more locally developed, higher risk exploration plays.