Remote listening helps control deep drilling
28 April 2008: news from CSIRO
Researchers in Australia working with the Commonwealth, Scientific and Industrial Research Organisation (CSIRO) have used a revolutionary system for controlling a deep drill that has been working at a depth of 300 metres below the surface of the ground. The system makes use of an extremely sensitive listening system, which is a type of microseismic device. The scientists concerned say that this has the potential to improve efficiency and reduce costs when directional drilling is required deep in the Earth for exploration and mining operations.
Picture: CSIRO: Preparing to cement an experimental geophone string in a borehole in central Queenland
This trial was performed in Queensland, Australia, at a test site coal field as part of an ongoing project to develop coal seam gas for commercial exploitation. The usual practice when coal seam drilling to obtain gas is to build a vertical production well that is linked to another borehole also connected to the main seam. The gas is released and channelled through this second borehole but only when it is connected to the sub-horizontal borehole. And thereby lies the difficulty.
Connecting the two is a bit hit and miss, as noone can see of tell exactly where the drill bit and the boreholes are. Using siesmic monitoring can pinpoint the location of the drill bit from the noise it is making as it drills. A multiple geophone array is used to improve the sound quality by boosting the signal to noise ration. Still, there is some contamination and the system is not yet perfect – although the filtering and cancelling algorithm used did allow the scientists to keep track of the drill bit fairly accurately, and to penetrate the target borehole first go.
This initial test will be followed up by more and further development and research, which is creating a lot of interest in the coal gas industry.
Read the original news release | 
