Methodologies for investigating gas in water bores and links to coal seam gas development2. Operational procedure for undertaking a field investigation and analysis

[摘要] Methane is a flammable gas that is generally found in the atmosphere and dissolved in natural water, albeit with small concentrations. Due to underground production from biogenic and thermogenic processes, dissolved methane concentrations can vary by orders of magnitude (from parts per million to tens of mg per litre and higher). This includes concentrations to the point where the methane forms gas bubbles (effervescence). These high concentrations of methane can be problematic for the operation of groundwater pumps and the gas may need to be safely vented. The monitoring of dissolved gas concentrations near coal deposits, either in typical coal seam target formations or in aquifers used for groundwater production, is important to avoid gas effervescence during groundwater extraction.This document was created to help standardise and simplify the process of collecting groundwater and gas samples for the analysis of methane concentrations. As has been previously reported, the best recommendation is to avoid degassing during pumping and to collect dissolved gas samples (containing no air bubbles) and when not possible, free gas should be collected in a consistent manner. An additional recommendation is that total dissolved gas pressures (TDGP) should be measured as this can be a simple proxy for high methane concentrations, without the need for laboratory analyses.

[发布日期] 2015-12-21 [发布机构] CSIRO

[学科分类] 地球科学(综合)