Groundwater monitoring results at petroleum well sites in the Beetaloo Sub-basin released by Santos

Issued 27 Nov 2019

The Scientific Inquiry into Hydraulic Fracturing in the Nothern Territory identified the need for a ground water monitoring program at each petroleum well site. The purpose of the program is to provide confidence that natural groundwater characteristics remain unaltered; or alternatively provide early detection of any contamination or altered hydrology that may occur as a result of petroleum activities. Monitoring results may also provide justification for further investigation or remedial action, if necessary.

Santos QNT Pty Ltd has submitted monitoring data for the Tanumbirini and Inacumba petroleum well sites on EP161 in the Beetaloo sub-basin, covering the period from December 2018 to October 2019. This report  fulfils the Code of Pratice: Onshore Petroleum Activities in the Northern Territory (the Code) (2019) requirement for 6 months of baseline monitoring of groundwater at a well site prior to undertaking hydraulic fracturing activities. This was also a condition of Ministerial approval of the Santos McArthur Basin 2019-2020 Hydraulic Fracturing Program Environment Management Plan (EMP).

To comply with the Code, companies are required to submit groundwater monitoring data quarterly, with the Department of the Environment and Natural Resources committed to publishing the monitoring  results from interest holders.

The Santos groundwater monitoring program consists of:

  • a Control Montoring Bore (CMB), which is located “upstream’’ and within 100m of each planned or existing petroleum well pad, screened across the Gum Ridge aquifer in compliance with the Code
  • an Impact Monitoring Bore, which is located 20m “downstream” of the location of each petroleum well.

These bores enable a comparison of the groundwater upstream and downstream of the petroleum well, to allow for an immediate identification of any variation in the groundwater that can be directly related to the petroleum activity.

The groundwater monitoring studies undertaken over the last 12 months at the Tanumbirini and Inacumba petroleum well sites operated by Santos identified very limited variation over the period, and no material changes in groundwater levels. The variation observed was within the bounds of what we understand to be natural variation and will continue to be monitored.

Santos has started to hydraulically fracture Tanumbirini 1 and is looking to start drilling Tanumbirini 2 and Inacumba in 2020, so the results gathered thus far provide an acceptable level of pre-activity baseline information.

To read the full report, please click here