Field characterization and 3D static modeling of the gas-bearing reservoirs, Scarborough field, Northern Carnarvon Basin, Australia

The Scarborough gas field, located in the Exmouth Sub-basin of the Northern Carnarvon Basin, is one of the largest undeveloped gas discoveries offshore Western Australia. Despite its favorable geological setting, development has been hindered by uncertainties in reservoir heterogeneity, fault behavior, and volumetric estimation. To address these uncertainties, this study presents a comprehensive geoscientific assessment of the field and constrains its recoverable gas potential. A multidisciplinary workflow was adopted, integrating seismic interpretation, petrophysical evaluation, core description, and 3D static reservoir modeling. The Barrow Group sandstones, comprising the Upper and Lower Fan complexes, form the primary reservoirs. The results reveal that the Lower Fan complex exhibits clean, well-sorted quartzose sandstones with good reservoir development. It is characterized by average good porosities (22–29 %) and net pay thicknesses (17–38 m), along with low water saturation, making it the primary target for hydrocarbon production. The Upper Fan contains more argillaceous, heterogeneous units with low reservoir quality. Seismic attribute analysis confirms the presence of direct hydrocarbon indicators, including flat spots, phase reversals, and amplitude shadows, as well as localized paleo-leakage features. Structural modeling reveals an NE–SW trending fault-controlled anticline with four-way dip closures and mixed fault-sealing behavior. Fault seal analysis indicates high Enhanced Shale Gouge Ratios and low transmissibility in key segments, supporting trap integrity. Static probabilistic volumetric modeling indicates a median (P50) gas initially in place (GIIP) of 10.31 TCF, with a P10–P90 range of 9.01–11.07 TCF, and P50 recoverable gas volume of 7.67 TCF, with a P10–P90 range of 6.73–8.43 TCF; in all cases, Lower Fan complex consistently contributes approximately 75–80 % of total gas volumes. These results provide a robust foundation for future dynamic modeling, development planning, and potential post-depletion CO 2 storage, leveraging the reservoir’s depth, continuity, and containment capacity.