Saucer-shaped sandstone intrusions: a global deepwater play?

Large-scale sandstone intrusions are well known from the North Sea and the Faroe-Shetland basins. Similar examples have recently been documented using high-quality 3D seismic volumes from sedimentary basins in the Barents Sea and the Lower Congo Basin. A previously unknown set of sandstone intrusions was recently discovered using high-quality 3D seismic data from the northern San Joaquin Valley. In all cases the host sediments are deepwater mudstones, ranging from siliceous oozes to hemipelagic muds. Some of the host mudstones are polygonally faulted and some are not. Together, these examples demonstrate that sandstone intrusions are important components of deepwater successions across the globe. In the North Sea, the intrusions form high-quality oil reservoirs with volumes of tens to hundreds of million cubic metres, porosities of 0.2-0.4 and permeabilities of several Darcy. We conclude that sandstone intrusions are likely to be an overlooked and potentially prolific play in many deepwater successions around the world.