This paper documents and describes through the use of 3D seismic data a prolific mud volcano province within the Eastern Mediterranean. As many as 386 mud volcanoes were mapped within the post-salt succession of the western slope of the Nile Cone, offshore Egypt, using high resolution 3D seismic data. The mud volcanoes within this field display significant geometrical variability in diameter (c. 550 m to c. 5660 m), height (c. 25m to c. 510 m) and volume (c. 0.1 km 3 to c. 3.3 km 3) and lie at depths ranging from c. > 6000 m subsea to c. 3100 m at the seafloor. A close spatial relationship between mud volcanoes and base-salt depressions and regions of anomalous thinning within the immediate pre-salt succession, combined with documented core samples taken from mud volcanoes within this region present a powerful argument for a pre-salt source of mud. 3D seismic interpretation and volumetric analysis of these mud volcanoes and their source region permit the definition and quantification of their depletion zones. A conceptual model for a dynamic liquefaction and sediment withdrawal process is proposed whereby mud is fed into a central conduit as the depletion zone propagates radially and episodically outwards resulting in a the formation of a concentric depletion zones. Prolonged mud volcanism within this region over the last ~5.3 Ma implies the potential for long lived pre-salt overpressure and continued mud volcanism following the catastrophic hydrodynamic impact of the Messinian Salinity Crisis. It is suggested that the scale of mud volcanism means that this region should be considered as among the largest mud volcano provinces in the world.

This study documents the seismic expression of the conduits underlying over 350 mud volcanoes that were erupted in an area of the western Nile Cone in the past 5.3 Myr. The study is based on a c. 4300 km 2 3D seismic survey. The conduits are interpreted to transect the >1000-m-thick Messinian Evaporite succession, demonstrating that the eruptive process is sufficiently dynamic to breach the formidable seal represented by the evaporites. The mud volcano conduits are remarkably similar in geometry and seismic characteristics to many previously described examples of fluid escape pipes. They are vertical to subvertical structures with a crudely cylindrical geometry, but that can either widen or narrow upwards towards their upper terminations in the mud volcano edifices. Imaging at depth within the Messinian Evaporites and pre-evaporite successions is more uncertain, but direct sampling of mud from surface volcanoes suggests a pre-Messinian source, confirming the seismic interpretation that they root within presalt stratigraphy. A conceptual model for the genesis of these mud volcano conduits through salt is proposed, for which hydraulic fracturing is driven by high overpressures that developed in the presalt source stratigraphy as a response to the Messinian Salinity Crisis. Dissolution and removal of evaporites resulting in fracturing and collapse via a stoping mechanism is a slow process by comparison to hydraulic fracturing but is argued to potentially contribute to conduit formation. The analysis presented here demonstrates the potential for bypassing a >1-km-thick unit of sealing evaporites via focused fluid and sediment mobilisation from deeper overpressured cells in other salt basins worldwide, and has significant implications for hydrocarbon exploration, CO 2 sequestration and nuclear waste disposal.

3D oil migration modelling of the Statfjord area of the Northern North Sea has led to increased understanding of the migration routes and definition of oil migration fairways. The majority of discovered fields in the Statfjord area lie on fault block ridges. Migration modelling demonstrates that they were filled by oil generated from the Viking Graben, East Shetland and Marulk basins, migrating stratigraphically downwards from the Upper Jurassic Draupne Formation source rock into the Middle Jurassic Brent Group sandstones. Thereafter, lateral migration in a fill–spill manner occurred along the axes of the ridges. Locally, petroleum also migrated laterally through both Upper and Lower Jurassic sandstones. The migration modelling has been combined with geochemical source rock and oil correlation resulting in increased confidence. For the first time we have been able to quantitatively model and visualize the complex petroleum system of the area and gain an insight into its development through geological time.

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The Middle East hosts a wide range of different geological setting, a large number of which exhibit structural complexity and hence can benefit from depth imaging. These structurally complex areas range from over thrust zones on the U.A.E -Oman border to salt structures in the Gulf of Suez and fault shadow problems in the Western Desert of Egypt in addition to offshore Egypt