Stratigraphic forward model of Springbok Sandstone sedimentation controlled by dynamic topography

After a long history of conventional gas exploration, the eastern Surat Basin in Queensland has developed as an active regional exploration target for coal seam gas, hosting large gas reserves. Interest in understanding basin fill mechanisms for petroliferous basins has grown in response to their economic significance. The Surat Basin is characterised by sedimentary successions with geometric complexity due to difficulty in correlation of coal splitting, interburden facies, and overburden channel belts. The uncertainty increases away from well control, in particular towards the centre where the basin is sparsely drilled. The forward modelling in LECODE (landscape evolution climate ocean and dynamic earth) is an innovative geomorphic and stratigraphic forward modelling code capable of simulating surface evolution and clastic sedimentary processes in 3D through geological time. This numerical tool can be used to test geological scenarios and predict the associated grain size distribution and sediment dispersal as a high-resolution synthetic stratigraphic record. This work focuses on a stratigraphic forward model developed for the Springbok Formation (Late Jurassic) within the Surat Basin. The simulated stratigraphy matches with models proposed by companies, highlighting a depocenter trending northwest–southeast. The formation is divided in two units: lower Springbok, defined by a fining-upward sequence and characterised by high-accommodation space and overfilling processes; and upper Springbok, described as an overall fining-upward sequence, with locally coarsening-upward wedge (conformable with the Weald Sandstone). The 3D basin simulation forecasts high heterogeneity of depositional geometries and stratal termination in depocentral and marginal areas.