Injection of Coal Seam Gas Water into the Central Condamine Alluvium – Site Prioritisation: Final Report

The Queensland Department of Environment and Resource Management (DERM) is advancing the Healthy HeadWaters Coal Seam Gas (CSG) Water Feasibility Study, which, among other things, is intended to develop knowledge and tools needed to understand and manage the potential impacts of CSG extraction on groundwater systems. As part of the Healthy Headwaters Project, DERM is assessing the feasibility of injection of treated CSG water into the Central Condamine River Alluvium (CCRA) to assist in recharging the depleted aquifer while also providing a water disposal option, and potentially mitigating future impacts that may be caused by CSG water extraction. As part of these assessments, DERM has asked Klohn Crippen Berger, Ltd. (KCB) to develop a prioritised ranking of potential injection sites identified in Activity 6.1. This report presents the results of these site prioritisation efforts.

Site prioritisation considered factors that may influence the likelihood of success of shortor long-term injection trials, including lithology, depth to aquifer unit, proximity to potential groundwater discharge, access, proximity to injection water source, and impacts to the general public. The site prioritisation processes resulted in a qualitative numerical score for each site, and a ranking of the top sites for shallow and deep injection. Priority sites are those that, based on available information, appear to offer the best combination of lithology, access, and other factors for successful injection trials.

Previous studies have identified, and in most cases, ranked, key data gaps relevant to the feasibility of injecting water into the CCRA. Site prioritisation activities undertaken during this study generally confirm previously identified data gaps. Prior to full-scale injection trials, it will be necessary to address critical data gaps.

A conceptual field program was designed to address critical data gaps. The field program is designed to generate data and information necessary to make injection rate and volume estimates for future injection programs. Major elements of the conceptual program are:

  • Geophysics: to support drill planning and drill target identification.
  • Test Drilling: to collect samples and provide geologic information.
  • Test Pumping and Injection trials: to collect aquifer hydraulic properties and to evaluate the degree of connectivity between various systems.
  • Monitoring: for ongoing support of these programs as they mature.

Injection trials are recommended as part of the field program for selected areas, to provide for a comparison between estimated and actual injection rates and volumes for each area, and to provide other critical information needed for proper evaluation and design a large-scale injection program for the CCRA.

This study has identified priority sites for shallow and deep injection trials based on existing information, identified key data gaps in geologic and hydrogeologic knowledge of the sites, and provided a detailed conceptual field program for further characterisation of these sites in support of advancement of the CCRA injection program.

Klohn Crippen Berger Ltd. 2012. “Injection of Coal Seam Gas Water into the Central Condamine Alluvium – Site Prioritisation: Final Report.” Prepared for State of Queensland (Department of Environment and Resource Management).

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