Automating conceptual models to easily assess trap integrity and oil preservation risks associated with fault reactivation

Extensive Neogene fault reactivation and leakage in the Timor Sea, Australian North-West Shelf, has long been identified as the likely cause for traps in the region being dry or underfilled, despite widespread evidence for hydrocarbon charge and larger palaeo-hydrocarbon columns than those preserved today. A structural model has been previously proposed (Gartrell et al., 2005) to explain the distribution of palaeo- and live hydrocarbon columns. This basic geometrical model is used to define the volume of closure that is protected from fault reactivation, thereby providing the potential for preserving hydrocarbons. Although the model is retrospectively successful in identifying which traps contain hydrocarbons, application to other areas is subjective. To assess the application of the Gartrell et al. (2005) concept a computational model has been generated and applied to a regional 3250 km2 seismic interpretation, allowing sensitivity testing of the critical input parameters.The automation has allowed us to demonstrate that the model successfully identifies dry traps and derives reasonable approximations of hydrocarbon–water contacts in commercial accumulations. Therefore, the basic geometrical model is deemed valid to apply to other hydrocarbon provinces, both frontier and mature, that are adversely impacted by fault reactivation after hydrocarbon charge.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We examine fault reactivation in the Timor Sea, Australian North-West Shelf. ► Fault reactivation suspected of being the major cause of hydrocarbon leakage. ► Basic geometric models are used to determine potential hydrocarbon traps and amount of reactivation. ► The model has been tested on a regional-scale interpretation with good results.