ILLAWARRA Coal’s Exploration team has introduced an innovative survey technique which is currently in use in the Menangle residential area.
The technique which is faster, less invasive and more environmentally sensitive than traditional seismic techniques, will provide important information regarding the company’s Appin West mine operations.
Adapted by Illawarra Coal from the petroleum industry, the vibroseis seismic survey method uses a truck mounted vibration source to look deep beneath the ground, rather than the traditional means of drilling lines of seismic shot holes to provide a conduit for an explosive energy source.
Illawarra Coal’s Manager Communication and Consultation Rosanne Moore said the Company was committed to the use of environmentally sound mining practices wherever possible and the vibroseis seismic survey method was just one example of how it could achieve that.
“Traditionally, the exploration team drill a 14 metre deep hole, 89mm in diameter and place a small charge at the bottom of the hole to produce the energy,” she said.
“The new technique, which can be used in relatively flat open areas or along roadways, alleviates the need for surface shot hole drilling, which means less impact — important in areas of high density housing.
The Hemi-60 Vibrator was originally developed for the petroleum industry for deep seismic exploration but has been adapted by Illawarra Coal for high resolution shallow seismic reflection techniques.
The methodology involves the use of a truck mounted vibration system that inputs energy into the ground via a composite plate.
The plate is lowered onto the road and the weight of the truck is applied to a hydraulic jack.
A vibrating frequency is then applied to the road for 12 second periods ranging from 10 to 150 Hertz.
The device was trialled last year with the aim to determine whether the unit was capable of inputting sufficient energy into the ground to image the Bulli Coal seam which in parts is some 550 metres below the earth’s surface.
“The results from the trials proved to be very encouraging, with the Bulli seam structure interpreted from the seismic data with sufficient confidence,” Moore said.
“The advantages certainly are obvious: faster survey time, no preparation drilling shot holes; lower impact on the environment, less time in the field; and safer, with no handling of explosives.”
Although the resulting seismic data is not as high in resolution as data acquired using conventional techniques it does provide the ability to identify any significant structures that would or could impact on longwall mining operations and is a useful tool for mine planning.
Other tests were completed by noise and vibration consultants to determine the outputs from the Hemi-60 so that all field operations would comply with relevant company health and safety standards.
Rosanne Moore
Manager Communication and Consultation
Illawarra Coal
Rosanne.moore@bhpbilliton.com
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