Abstract
Analysis of dissolved methane and volatile organic compounds (VOCs) in water is crucial in monitoring the underground water quality, specific to shale oil and gas subsurface activities. Existing methods for monitoring these analytes generally rely on manual sampling at hydrogeological boreholes followed by off-line chromatography-based laboratory analysis. These methods are labor intensive and prone to errors. In addition, they do not capture the dynamic variations, which are particularly interesting in the occurrence of methane. In this work, a new sensor-based instrumentation for in-situ detection and measurement of methane and VOCs in subsurface environments is presented. The methane detection method relies on the Non-Dispersive Infrared technology whereas VOCs are detected using the principle of photoionization detection.
It is demonstrated that the system has a relatively short response time combined with low detection limits for methane and VOCs. This makes the system suitable for monitoring aquifers in shale gas exploration sites with a fairly high temporal resolution thus giving information on dynamic variations in the methane and VOC concentrations.
