OVERVIEW
This integrated Upper Permian study focuses on the upper part of the Wagina and Dongara Sandstones and their transition into the Hovea Member across a 2000+ km² area encompassing both mature petroleum fields and new discoveries in the Dandaragan Trough.
Through detailed core logging, cross-sectional stratigraphic analysis, and new quantitative palynological sampling, this study aims to improve depositional models and identify untapped prospectively across these key intervals.
BACKGROUND
The northern Perth Basin has long been regarded as a proven and mature hydrocarbon province undergoing progressive field depletion (e.g. Dongara, Yardarino, Mondarra, Beharra Springs, Woodada) of mostly upper Permian sandstone and limestone plays at depths 1600–3300 m since first production in the 1970s. The basin’s prospectivity has, however, been considerably revitalised in the past 10 years following discovery of the Waitsia Field and some of the largest conventional onshore reservoirs in Australia hosted in previously marginally appraised lower Permian plays.
Renewed petroleum activity in the northern Perth Basin has unsurprisingly led to focus exploration endeavours on the lower Permian reservoirs. Nevertheless, a 2MMscfd gas flow rate in Strike Energy’s L24 (2022) and two oil discoveries representing 20.5 MMboe (2C contingent resources) in Mineral Resources’ EP426 (2023–2024) in the upper Permian Dongara–Wagina sandstones demonstrated porosity preservation at depth >3000 m and untapped economic potential in areas that were previously considered high-risk and unattainable.
Despite the recent discoveries, considerable uncertainties remain as to the spatial distribution of late Permian facies belts, the depositional and structural controls that drove sediment deposition, and the stratigraphic evolution of the upper Permian succession. Ferdinando and Longley (2015) identified that nearly a quarter of dry wells targeting upper Permian plays are due to a lack of porous reservoir lithologies.
DETAILS
This multi-client study proposes to conduct sedimentological, stratigraphic, and palynological analyses of the upper part of the upper Permian interval (the upper part of the Wagina Sandstone and the Dongara Sandstone) and, where available, its transition into the Hovea Member in an area >2000 km2 encompassing the historical petroleum fields on the Dongara and Beharra Springs terraces and the new hydrocarbon discoveries in the Dandaragan Trough.
The sedimentology component aims to characterise depositional environments, identify surfaces of sequence-stratigraphic significance, and revisit the current paleogeographic maps and depositional models for the reservoir succession. It involves generation of graphic sedimentary logs of open-file cores from fourteen wells located in Exploration and Production permits L14, L1, L2, EP368, EP320, EP469, L11, L22, and L24 (Table 1).
The stratigraphic analysis aims to reconstruct the stratal architecture of the upper Permian interval. It consists in the production of basin-scale cross-sections, where core logs will be used to calibrate wireline log responses of corresponding intervals. Allogenic surfaces of sequence-stratigraphic significance bounding major sedimentary units will be correlated in historical petroleum fields and propagated downdip into areas of new hydrocarbon discoveries (Figure 1). Cross-sections will be built using MGPalaeo’s AUSTRALIS database to ensure that correlated reservoir units are placed in a state-of-the-art biostratigraphic framework.
The palynology component consists in undertaking a quantitative palynological analysis based on core and cutting samples taken at various, organic-rich stratigraphic intervals in wells where biostratigraphic coverage in the upper Permian–lower Triassic interval is absent or limited. The infill sampling program will yield meaningful biostratigraphic constrains for the correlation of coeval units and provide paleoenvironmental indicators (i.e. distance from the shoreline) that will help refine the sedimentological model.
Table 1: Fourteen cored wells selected for the sedimentological analysis.
| Well | Sub-basin | Formation(s) | Material |
|---|---|---|---|
| Jingemia 4 | Dongara Terrace | Hovea Mbr, Dongara Sst, Wagina Sst, Carynginia Fm | Core 1-3 |
| Senecio 3 | Dandaragan Trough | Dongara Sst, Wagina Sst | Core 1 |
| Lockyer 1 | Dandaragan Trough | Dongara Sst | Core 1 |
| Yardarino 2 | Dandaragan Trough | Hovea Mbr, Dongara Sst | Core 2-7 |
| Hovea 3 | Beharra Springs Terrace | Hovea Mbr, Dongara Sst, Wagina Sst | Core 1-3 |
| Mondarra 1 | Dandaragan Trough | Dongara Sst | Core 4-6 |
| Mondarra 7 | Dandaragan Trough | Hovea Mbr, Dongara Sst, Wagina Sst | Core 1 |
| Apium 1 | Dandaragan Trough | Dongara Sst, Hovea Mbr | Core 1-2 |
| Dongara 11 | Dongara Terrace | Dongara Sst, Wagina Sst | Core 1-4 |
| Dongara 27 | Beharra Springs Terrace | Dongara Sst | Core 1 |
| Central Yardarino 1 | Dandaragan Trough | Dongara Sst, Bookara Sst | Core 1 |
| Yardarino 1 | Dandaragan Trough | Dongara Sst, Wagina Sst | Core 11-17 |
| Warradong 1 | Dandaragan Trough | Dongara Sst | Core 1-2 |
| Centella 1 | Dandaragan Trough | Dongara Sst, Hovea Mbr | Core 1 |
Figure 1: Location of proposed cross-sections (click on the image to enlarge).
OUTCOMES
The anticipated outcomes will include:
- a better characterisation of reservoir facies within an updated depositional and paleogeographic model that will allow to anticipate the type and regional extent of upper Permian reservoir units, and potentially predict heterogeneities, internal baffles, and stratal pinch-outs that are inherent to sedimentary systems.
- a revised sequence-stratigraphic framework that will increase the confidence in well-to-well correlations, reduce uncertainty in the regional mapping of coeval reservoir units, and help forecast sediment partitioning in downdip areas with limited well control.
- new palynological assignments for the upper Permian–lower Triassic intervals in wells with limited or absent biostratigraphic control.
DELIVERABLES
- Core descriptions at the 1:50 scale of 14 wells totalling 509 m of sedimentary strata.
- Integration with wireline logs, core photographs and RCA data. Core to well log shifts, where applicable.
- Tabulated cm-scale exports of sedimentological attributes (grain size, sorting, lithology, lithofacies, depofacies).
- Sedimentology report outlining lithofacies, depofacies, a proposed depositional model, and paleogeographic maps.
- Five basin-scale cross-sections with correlations of interpreted sequence-stratigraphic surfaces and units.
- Stratigraphic report detailing the proposed sequence-stratigraphic framework.
- New palynological assignments across the study interval.
For more information on this multi-client study, please contact us.
You must be logged in to post a comment.