The Surat and southern Bowen basins are complex multilayered aquifer systems extensively developed for private water use since the 1800’s and more recently for petroleum and gas (P&G). The Office of Groundwater Impact Assessment (OGIA) is responsible for the design of a regional monitoring network to support research, system conceptualisation and regional groundwater modelling.
OGIA is an independent entity established under the Water Act 2000. Since 2011, OGIA has been responsible for the assessment of cumulative groundwater impacts from P&G activities in the Surat Cumulative Management Area (CMA) – an area of overlapping impacts. Every three years, OGIA prepares an Underground Water Impact Report (UWIR) which establishes a groundwater monitoring network and identifies responsible tenure holders for the implementation. There are currently more than 500 monitoring points in the network which has required significant financial investment and support from tenure holders.
The objectives governing the design of the monitoring network are to improve understanding of system response within production areas; identify pressure changes near specific areas of interest; understanding of background trends in pressure; and to provide sufficient data for model calibration.
There are a range of challenges in the design and implementation of a network extending over an area of 100,000 km2 encompassing more than 20 hydrostratigraphic units, varying hydrochemical conditions, multiple fluid phases and with monitoring depths up to 1,500 m below ground. As a result, construction and instrumentation differ significantly and necessitate careful data treatment and density correction requirements. There is also a need to balance the opportunity of existing infrastructure and maintaining adequacy of the regional network.
This paper presents the unique challenges, opportunities and learnings in establishing such an extensive and complex network. The presentation will focus on the approach to network design and how key challenges have been collaboratively overcome by industry and OGIA.