Using 3D Geomechanical Modelling To Evaluate Stress-related Fault Seal Risk – A Timor Sea Case Study

Observations from the Timor Sea suggest that the high incidence of breached Jurassic traps is a result of recent fault reactivation. Based on comparison between structural evolution and charge history, it has been proposed that the variation in strain accommodation between faults was critical in determining up-fault flow patterns. A geomechanical 3D model is used to simulate the response of trap-bounding faults to extensional reactivation. The model makes predictions on stresses/strains and fluid flow partitioning and is used to characterise the interaction between the deformation state and fault seal efficiency over an area including the Laminaria and Corallina oil fields. When integrated with well data and evidences of fluid remigration, the model results show their ability to constrain trap integrity predictions and isolate leaking/sealing fault segments. The model captures the inhomogeneous distribution of sealing fault segments driven by strain partitioning and structural architecture. It emphasises that fault tip interaction, fault growth process and fault plans arrangement all play a major role in controlling fault seal evolution.