Enhancing geological and hydrogeological understanding of the Precipice Sandstone aquifer of the Surat Basin, Great Artesian Basin, Australia, through model inversion of managed aquifer recharge datasets

Abstract

The Precipice Sandstone is a major Great Artesian Basin aquifer in the Surat Basin, Queensland, Australia, which is used for water supply and production of oil and gas. This report describes use of observed groundwater pressure responses to managed aquifer recharge (MAR) at a regional scale to test recent geological descriptions of Precipice Sandstone extent, and to inform its hydrogeological conceptualisation. Since 2015, two MAR schemes have injected over 20 GL of treated water from coal seam gas production into the Precipice Sandstone, with pressure responses rapidly propagating over 100 km, indicating high aquifer diffusivity. Groundwater modelling of injection and inversion of pressure signals using PEST software shows the spatial variability of aquifer properties, and indicates that basin in-situ stresses and faulting exert control on permeability. Extremely high permeability, up to 200 m/day, occurs in heavily fractured regions with a dual-porosity flow regime. The broader-scale estimates of permeability approach an order of magnitude higher than previous studies, which has implications for the management of water resources in the Precipice Sandstone. Results also show the Precipice Sandstone to have broadly isotropic permeability. The results also support a recent geological interpretation of the Precipice Sandstone as having more limited lateral extent than initially considered. The study shows the effective use of MAR injection data to improve geological and hydrogeological understanding through groundwater model inversion. It also demonstrates the utility of combining hydrogeological and reservoir-engineer datasets in areas explored and developed for both groundwater resources and oil and gas resources.

Metal Mobilization From CO2 Storage Cap-Rocks: Experimental Reactions With Pure CO2 or CO2 SO2 NO

“…The potential impacts to these lowsalinity aquifers, in the unlikely event of a CO 2 leakage, is one major risk factor often considered (Kharaka et al, 2006;Cheung et al, 2009;Kharaka et al, 2010;Kirsch et al, 2014;Kharaka et al, 2018). In some cases, the reservoir itself may be a low-salinity aquifer, in which case the potential short or long impacts around the storage site itself may be a concern (Hodgkinson and Grigorescu, 2012;Hayes et al, 2020). During geological storage, CO 2 will dissolve in formation water forming carbonic acid and causing acidification, the extent of which depends on the buffering capacity of the formation water and rock (Pearce et al, 2022c).…”

“…The Westgrove Ironstone Member is located within the Evergreen Formation (Figure 1), and is also considered a regional-scale seal (La Croix et al, 2019a;La Croix et al, 2020a;La Croix et al, 2020b;Pearce et al, 2021c). The Hutton Sandstone is the low-salinity aquifer overlying the Evergreen Formation, and in other areas of the Surat Basin, both the Hutton Sandstone and the Precipice Sandstone are sources of water for agriculture, mining, livestock, or town water bores (Suckow et al, 2018;Hayes et al, 2020). The native quality of the groundwater within these aquifers is very variable with location, being fresh to brackish near recharge in the northern part of the basin, but less well known in the deeper southern part of the Surat Basin, which is now being considered for large-scale CO 2 storage (Hodgkinson and Grigorescu, 2012;Feitz et al, 2014;Pearce et al, 2019a;Pearce et al, 2020;Pearce et al, 2022b).…”

Comparative Assessment of Methods for Coupling Regional and Local Groundwater Flow Models: A Case Study in the Beijing Plain, China

“…Since the design of the grid is very flexible, the grid refinement is no longer restricted by the shape grid and refinement area. Multi-scale models can be constructed by the USG method either when the boundary of the local model area is irregular or the hydrological stresses change in the local area might have a significant influence on the larger region [19,20]. Finer grid resolution can be used to refine the area near river channels [21,22] or only on the model top layer [23] to investigate surface and groundwater interaction.…”