Following the rapid expansion of coal seam gas (CSG) in the Surat Basin in 2005, there has been continued investment in hydrogeological research by industry, research organisations and Government. Outcomes often challenge paradigms, but importantly improve understanding of these complex regional groundwater systems.
The Office of Groundwater Impact Assessment (OGIA) is responsible the assessment of cumulative groundwater impacts from petroleum and gas (P&G) activities in the Surat Cumulative Management Area (CMA) – an area of overlapping impacts. The role necessitates undertaking primary hydrogeological research and investigations, but also the collation and integration of hydrogeological research across all other organisations.
Extensive new information and understanding has become available in recent years. This presentation highlights how new learnings have been integrated to provide the basis for regional impact assessment. These include:
Revised basin architecture following the development of a new hydrostratigraphic model based on primary interpretation of 4,800 CSG well wireline logs and other datasets.
- Increased confidence in the estimation of unmetered stock and domestic (S&D) using a new methodology for estimating this component of the water balance.
- Applying a multiple lines of evidence approach to connectivity assessments in priority areas using multi-variate cluster analysis, geological investigations and pump tests.
- Revised recharge estimates for each aquifer based on an extension of saturated zone chloride mass balance (CMB) calculations across the whole of the CMA.
- Analysis of groundwater level data for around 12,000 bores to determine trends, develop potentiometric surface maps and determine groundwater flow directions.
- Detailed hydrogeological conceptualisation for 17 priority spring complexes.
This presentation focuses on new methods, knowledge and a contemporary approach to conceptualisation – multidisciplinary, collaborative and research guided by management needs. The conceptualisation report will be updated every three years to provide a reference point for hydrogeologists working on the GAB