FTG - full tensor gravity gradiometry

Norwest has developed expertise in interpreting full tensor gravity gradiometry imaging (FTG), a survey technology that can be meshed with existing seismic and other data such as regional well logs to cost-effectively give a much clearer picture of local geology.

Norwest has successfully used FTG in its southern England permits as well in the TP/15 block and the North Erregulla project area (EP368 and EP426 permits) in the northern Perth Basin.

Norwest's FTG in both Australia and the UK have increased the company's confidence in its preliminary geological models while also providing more detail for a deeper understanding of local subtleties and variations on the models. It has played a valuable role in fast-tracking the company's exploration for a relatively modest outlay.

This technology fits perfectly with Norwest's strategy of using low-cost, high-impact exploration tools whenever practicable. The Company has highly sophisticated software for FTG interpretation and believes FTG offers a real edge for explorers that have the expertise to use it effectively.

The FTG data on the left confirms the seismic interpretation map (Top Reservoir) on the right. The hotter colours represent structural highs ie Purple represents the basement high on the left and red represents the structural high on the right. The white line indicates a plan view of the well path being drilled from land to the top reservoir

More data for less cost

Acquired from a light aircraft flown at low altitudes, an FTG survey measures the gradient of the Earth's gravity field, recording shifts in the density of underlying rocks. It can deliver results on both shallow and deeper targets and can provide strong 3D image quality and a detailed exploration dataset, helping petroleum explorers and producers to reduce risks and increase returns.

The technology is also highly cost-effective. On a kilometre-by-kilometre basis, FTG surveys cost significantly less than seismic acquisitions.

Other advantages over seismic

FTG is very well suited to surveying "transition zones" - coastal areas linking land and sea. Such zones have highly varied terrain and big variations in sea-bottom depths and sediment thicknesses. This tricky geology makes seismic acquisition and interpretation difficult and costly and compromises seismic data quality.

Norwest's three UK permits are transition zone blocks, as is the TP/15 permit, the Company's offshore coastal permit in the northern Perth Basin. In the case of TP/15, the Xanadu prospect could not be easily defined with seismic alone. FTG helped Norwest better define the Xanadu structure and increased confidence the structure closes to the northeast. In the UK, FTG was also useful for its ability to provide survey results without disturbing normal activity in a heavily populated area. It would have been all but impossible to get similar coverage from seismic in this densely populated and built-up region.FTG - Full-tensor gravity gradiometry

This technology fits perfectly with Norwest’s strategy of using low-cost, high-impact exploration tools whenever practicable. The Company has highly sophisticated software for FTG interpretation and believes FTG offers a real edge for explorers that have the expertise to use it effectively.