Browsing by Author "Nisbet, EG"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- ItemAssessing connectivity between an overlying aquifer and a coal seam gas resource using methane isotopes, dissolved organic carbon and tritium(Nature, 2015-11-04) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJCoal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ13C-CH4), groundwater tritium (3H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ13C-CH4 versus CH4 concentration, in association with DOC concentration and 3H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity. © The Authors. This work is licensed under a Creative Commons Attribution 4.0 International Licence. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons licence, users will need to obtain permission from the licence holder to reproduce the material.
- ItemAssessing connectivity between an overlying aquifer and a coal seam gas resource using methane isotopes, dissolved organic carbon and tritium(National Centre for Groundwater Research And Training, 2015-11-03) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJCoal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ13C-CH4), groundwater tritium (3H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ13C-CH4 versus CH4 concentration, in association with DOC concentration and 3H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity. © The Authors.
- ItemAssessing the hydraulic connection between fresh water aquifers and unconventional gas production using methane and stable isotopes(European Geosciences Union, 2015-04-12) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJUnconventional gas developments pose a risk to groundwater quality and quantity in adjacent or overlying aquifers. To manage these risks there is a need to measure the background concentration of indicator groundwater chemicals and to map pathways of hydraulic connectivity between aquifers. This study presents methane (CH4) concentration and isotopic composition, dissolved organic carbon concentration ([DOC]) and tritium (3H) activity data from an area of expanding coal seam gas (CSG) exploration and production (Condamine Catchment, south-east Queensland, Australia). The target formation for gas production within the Condamine Catchment is the Walloon Coal Measures (WCM). This is a 700 m thick, low-rank CSG resource, which consists of numerous thin discontinuous lenses of coal separated by very fine-to medium-grained sandstone, siltstone, and mudstone, with minor calcareous sandstone, impure limestone and ironstone. The thickness of the coal makes up less than 10% of the total thickness of the unit. The WCM are overlain by sandstone formations, which form part of the Great Artesian Basin (GAB). The Condamine Alluvium fills a paleo-valley carved through the above formations. A combination of groundwater and degassing air samples were collected from irrigation bores and government groundwater monitoring boreholes. Degassing air samples were collected using an SKC 222-2301 air pump, which pumped the gas into 3 L Tedlar bags. The groundwater was analysed for 3H and [DOC]. A mobile CH4 survey was undertaken to continuously sample air in and around areas of agricultural and unconventional gas production. The isotopic signature of gas from the WCM was determined by sampling gas that was off-gassing from a co-produced water holding pond as it was the largest emission that could be directly linked to the WCM. This was used to determine the source signature of the CH4 from the WCM. We used Keeling plots to identify the source signature of the gas sampled. For the borehole samples these plots assume that there are only two sources of CH4, each with a unique isotopic signature. When the two sources mix in varying proportions they will plot along a straight line in the Keeling plot. Geometric mean displacement was used to fit a regression line and determine the intercept value. Within the Keeling plot, samples clustered according to their 3H and [DOC] values. One cluster is associated with near surface biological processes, while the other cluster can be attributed to gas sourced from the WCM. This indicates that in places there is hydraulic connectivity between the WCM and the overlying Condamine Alluvium. The results from this case study demonstrate that measuring 3H activity, [DOC] and CH4 concentrations in combination with CH4 isotopic analysis can provide an early indicator of hydraulic connectivity in areas of expanding unconventional gas development. © Author(s) 2015. CC Attribution 3.0 License.
- ItemDetecting connectivity between an overlying aquifer and a coal seam gas resource using methane isotopes, dissolved organic carbon and tritium(Association of Australian Cotton Scientists, 2015-09-09) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJThere is public concern that coal seam gas (CSG) production will affect groundwater quality and quantity in overlying aquifers used to support irrigation, stock and domestic water supplies. To assess this risk there is a need to map pathways of hydraulic connectivity using geochemical and isotopic measurements. We demonstrate that measurements of methane (CH4) concentration and isotopic composition, dissolved organic carbon (DOC) concentration and tritium (3H) activity data highlight potential pathways of hydraulic connectivity between the Walloon Coal Measures (WCM – the target formation for CSG production) and the Condamine Alluvium, south-east Queensland, Australia. At 19 locations, both groundwater and degassing air samples were collected from irrigation bores. Degassing air samples were pumped into 3 L Tedlar bags. This air was analysed for both its methane concentration and isotopic signature. The groundwater was analysed for 3H and [DOC]. To determine the isotopic signature of the WCM, CH4 ambient air samples were collected adjacent to CSG coproduced water holding ponds. We use isotope mixing plots to identify the isotopic source signature of CH4 in the air samples from the degassing irrigation bores and those adjacent to CSG water holding ponds. Within the mixing plots samples graph along clear trend lines, which allows gas sources to be assigned. These trends in the mixing plots indicate potential local hydraulic connectivity between the WCM and the overlying Condamine Alluvium.
- ItemDetecting hydraulic connection between fresh water aquifers and coal seam gas production using the isotopes of carbon in methane(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-10) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJNot provided to ANSTO Library.