CSIRO, Dutton Park 4102, Australia.
CSIRO, Dutton Park 4102, Australia.
Sci Total Environ. 2018 Sep 1;634:1246-1258. doi: 10.1016/j.scitotenv.2018.04.123. Epub 2018 Apr 18.
Large scale development of coal seam gas (CSG) is occurring in many sedimentary basins around the world including Australia, where commercial production of CSG has started in the Surat and Bowen basins. CSG development often involves extraction of large volumes of water that results in depressurising aquifers that overlie and/or underlie the coal seams thus perturbing their flow regimes. This can potentially impact regional aquifer systems that are used for many purposes such as irrigation, and stock and domestic water. In this study, we adopt a probabilistic approach to quantify the depressurisation of the Gunnedah coal seams and how this impacts fluxes to, and from the overlying Great Artesian Basin (GAB) Pilliga Sandstone aquifer. The proposed method is suitable when effects of a new resource development activity on the regional groundwater balance needs to be assessed and account for large scale uncertainties in the groundwater flow system and proposed activity. The results indicated that the extraction of water and gas from the coal seam could potentially induce additional fluxes from the Pilliga Sandstone to the deeper formations due to lowering pressure heads in the coal seams. The median value of the rise in the maximum flux from the Pilliga Sandstone to the deeper formations is estimated to be 85ML/year, which is considered insignificant as it forms only about 0.29% of the Long Term Annual Average Extraction Limit of 30GL/year from the groundwater management area. The probabilistic simulation of the water balance components indicates only small changes being induced by CSG development that influence interactions of the Pilliga Sandstone with the overlying and underlying formations and with the surface water courses. The current analyses that quantified the potential maximum impacts of resource developments and how they influences the regional water balance, would greatly underpin future management decisions.
大规模的煤层气（CSG）开发正在世界上许多沉积盆地进行，包括澳大利亚，那里的商业 CSG 生产已经在苏拉特和鲍文盆地开始。CSG 的开发通常涉及大量水的提取，这导致了覆盖和/或位于煤层上方的含水层的减压，从而扰乱了它们的流动模式。这可能会影响到用于灌溉、牲畜和家庭用水等多种用途的区域含水层系统。在这项研究中，我们采用概率方法来量化古内达煤层的减压情况，以及这种减压情况如何影响覆盖其上的大自流盆地（GAB）皮拉iga 砂岩含水层的流量。当需要评估新资源开发活动对区域地下水平衡的影响，并考虑到地下水流动系统和拟议活动中的大规模不确定性时，该方法是合适的。结果表明，由于煤层中的压力头降低，从皮拉iga 砂岩中抽取水和气体可能会导致更深地层的额外流量增加。从皮拉iga 砂岩到更深地层的最大流量增加的中位数估计值为 85ML/年，这被认为是微不足道的，因为它仅占地下水管理区 30GL/年的长期年平均提取极限的 0.29%。水平衡组成部分的概率模拟表明，CSG 开发仅会引起较小的变化，这些变化会影响皮拉iga 砂岩与上覆和下覆地层以及地表水之间的相互作用。目前对资源开发的潜在最大影响进行量化的分析，以及它们如何影响区域水平衡，将极大地支持未来的管理决策。
