Five baseline CSG projects are modelled in the Maranoa-Balonne-Condamine subregion (Figure 9). This includes three large-scale gas field developments supporting the three liquefied natural gas (LNG) projects on Curtis Island near Gladstone. These projects are considered to be baseline development, being commercially producing as of December 2012. The Queensland Curtis LNG (QCLNG) Project commenced in 2010, Australia Pacific LNG (APLNG) Project in 2011 and Santos Gladstone LNG (GLNG) Project in 2011. The Surat Gas Project and the Ironbark project have planned commencement dates after December 2012 and so do not meet the baseline definition for bioregional assessments (BAs). However, these two projects are reported in the Surat underground water impact report (UWIR) (QWC, 2012) and annual report (OGIA, 2014) based on information provided to OGIA by the tenure holders each year. Therefore, to ensure consistency with OGIA reporting, all five CSG projects in the Maranoa-Balonne-Condamine subregion that are represented in the current OGIA model (QWC, 2012) and reported in the 2014 annual report (OGIA, 2014) are considered to be part of the baseline for this Assessment. Table 6 summarises the CSG projects modelled by OGIA for this Assessment, including all CSG and conventional petroleum tenements.
Table 6 Coal seam gas projects modelled in the Maranoa-Balonne-Condamine subregion
In this table, results are presented for only that part of the coal resource development pathway (CRDP) that can be modelled.
ATP = authority to prospect, MLA = mining lease application, ML = mining lease, OGIA = Office of Groundwater Impact Assessment, PL = petroleum lease, P&G = Petroleum & Gas
The Surat Gas Project includes expansion of production at existing CSG fields operated by Arrow Energy Pty Ltd, including Stratheden, Kogan North, Daandine and Tipton West. While still undergoing formal approval, the staged expansion plans have been included in the OGIA model based on information provided to OGIA by the tenure holders each year. Projected water extraction from the expanded Surat Gas Project ranges from 13–35,000 ML/year over the 6100 km2 development area (Arrow Energy, 2013).
Origin Energy Limited’s Ironbark Project currently consists of a number of pilot CSG wells, appraisal wells and monitoring wells and therefore does not meet the baseline definition. However, it is included in the current OGIA model with a planned commencement date of 2016 based on information provided to OGIA by the tenure holders each year. The Ironbark Project occupies a relatively small area along the southern boundary of the Queensland Gas Company (QGC) central development area (Figure 11). Water extraction estimates are not publically available for the Ironbark Project at this time.
Projected additional water extraction from these two development projects represents a relatively small proportion of the 95,000 ML/year total water extracted from the Surat cumulative management area for petroleum and gas (P&G) production (and the Maranoa-Balonne-Condamine subregion) (QWC, 2012). The extraction volumes and their location among existing development projects mean that the consequences of their inclusion in the baseline for this Assessment are considered to be negligible. Therefore, the Surat Gas and Ironbark projects are both considered part of the baseline for this Assessment to ensure consistency with the Surat UWIR (QWC, 2012) and annual report (OGIA, 2014).
The planned commencement and cessation dates for each development that are provided to OGIA by the tenure holders each year are implemented in the OGIA model using the MODFLOW EVT package to represent groundwater extraction associated with CSG activities within each model grid cell. Optimal gas flow is typically achieved from CSG wells when the groundwater pressure is approximately 35–40 m above the coal seam. Maximum water extraction occurs in the initial years and the volume of water extracted reduces exponentially with time (QWC, 2012). The EVT package provides a convenient means by which a user-defined volume of water can be removed from the model that is constrained by additional control on the groundwater pressure. Figure 11 shows the planned commencement and Figure 12 the planned cessation of CSG production in the Surat CMA (OGIA, 2014). As gas field development is a progressive process, the tenements are not all developed and produced at the same time, but the process will occur in stages.
In this figure, results are presented for only that part of the coal resource development pathway (CRDP) that can be modelled.
CDA = Central Development Area, CSG = coal seam gas, NDA = Northern Development Area, QGC = Queensland Gas Company, SDA = Southern Development Area
Source: adapted from Figure 1 Planned commencement of CSG production as at October 2014 in OGIA (2014)
Figure 12 Planned cessation of coal seam gas production for the Maranoa-Balonne-Condamine subregion
In this figure, results are presented for only that part of the coal resource development pathway (CRDP) that can be modelled.
CDA = Central Development Area, CSG = coal seam gas, NDA = Northern Development Area, QGC = Queensland Gas Company, SDA = Southern Development Area
Source: adapted from Figure 1 Planned cessation of CSG production as at October 2014 in OGIA (2014)
