oa An Integrated Approach to Salt Basin Evaluation

Salt basins play a major role in the hydrocarbon industry but also are increasingly important as oil and<br>gas storage sites. They display a complex geodynamic evolution characterized by several phases of<br>halokinesis and associated sedimentation. Our approach to salt basins combines seismic, structural and<br>sedimentary studies with analysis of rheological properties, and geomechanic modelling. High<br>resolution reservoir quality studies in prospective salt basin sequences and new advances in microscale<br>porosity and permeability analytical techniques can now be taken to a predictive level for<br>exploration and serve to optimize production in existing fields. We illustrate these concepts with case<br>studies from Europe and the Middle East.<br>One classic area of salt tectonics is the Central European Basin System (CEBS). Here, the mobile<br>Permian Zechstein salt formed a large number of salt structures such as anticlines, diapirs, pillows,<br>sheets, stocks, and walls during an extended period of salt tectonic activity in Mesozoic and Cenozoic<br>times. Salt-influenced sedimentary responses to renewed phases of tectonism can be clearly discerned<br>from detailed sequence analysis based on seismic and log data combined with retrodeformation<br>modelling studies. High quality 3-D seismic data integrated with structural modelling improves the<br>definition of salt structure and associated sediment architecture in salt-controlled sequences.<br>The improved understanding of the tectonic and sedimentary evolution of salt structures and detailed<br>knowledge of the dynamics of subsurface salt has significant effects on seismic modelling, depth<br>conversion and interpretation of complex structures. Integrated analysis advances the prediction of<br>potential hydrocarbon reservoirs. Salt wedges which have formed by lateral extrusions during periods<br>of diapir emergence and reduced sediment accumulation as well as isolated carbonate “rafts” and<br>“stringers” can form potential hydrocarbon traps and thus represent an alternative exploration target in<br>most salt-rich hydrocarbon provinces. Knowledge of the geometry and properties of salt as well as the<br>surrounding host rocks significantly improves the prediction of seals and their capacity and helps in<br>planning drilling operations.