CoalGAS has been awarded an ACARP Project (C28007) to investigate the impact of core sample recovery time on accuracy of gas content measurement

It is generally accepted in core sample gas content testing in Australian underground coal mines that a “correction factor” is added to the measured gas content when the time to recover the core sample from the coal seam exceeds 40 minutes. The addition of the measured gas content and the correction factor amounts to the reported gas content (QM) provided to coal mines.

For mines that require the use of gas drainage to reduce gas content below defined outburst threshold limits (OBTLV), the addition of the correction factor may cause the reported gas content value to be greater than the OBTLV. In such cases, these mines are required to further reduce gas content and retest the area to confirm the gas content (reported gas content) has been reduced below the OBTLV prior to the area being approved for mining, in accordance with the mine’s Permit to Mine approval process. The potential impact of delays to achieve gas content compliance for a mining area may cause delays to mine development operations while additional work, such as increased gas drainage drilling, extended gas drainage time and additional core sample collection and gas content testing, is carried out to reduce gas content and confirm the gas content has been reduced below OBTLV.

CoalGAS has completed some initial testing at one mine that shows recovery time has minimal impact on the accuracy of gas content measurement. This is a potentially significant finding that suggests the addition of the gas content correction factor is unnecessary and may overstate the gas content in the area where the coal sample was collected.

With support from ACARP, CoalGAS plans to expand the testing program to carry out similar tests in a broad range of Australian coal seam conditions. All Australian coal mines that employ underground-to-inseam (UIS) drilling to pre-drain coal seam gas prior to mining are invited to participate in this study.

What do you get?

  • Site specific assessment of the impact of core sample recovery time on gas content accuracy;
  • Potential to avoid the addition of a gas content correction factor to reported gas content values;
  • Potential to avoid a situation where measured QM is below OBTLV and the addition of the gas content correction factor causes the reported QM value to be greater than the OBTLV

What does it cost?

  • Mines participating in this study will be required to undertake a program of core sample collection and testing in accordance with a standard testing program defined by CoalGAS;
  • The test program requires a series of core samples to be collected from a UIS borehole that are tested to determine the impact of extended core sample recovery time on the accuracy of gas content measurement.

Want to participate?

  • For more information and to find out how your mine can participate and benefit from this study, contact Dennis Black via Email: or Mobile: 0401999542