Reservoir architectures of interlava systems – a 3D photogrammetric study of Eocene cliff sections, Faroe Islands

Following the intra-volcanic Rosebank discovery in the Faroe–Shetland Basin, NE Atlantic, there has been a need to find suitable analogues to characterize reservoir architectures, connectivities and compartmentalization of interlava clastic beds. The Faroe Islands, situated c. 160–190 km to the NW of this discovery, are an exposed remnant of the Palaeogene lava field host and the near-vertical cliff sections afford the opportunity to map lateral variations over many kilometres. This was achieved through 3D photogrammetry based on high-resolution digital photographs taken from a helicopter. The study focused on the Eocene Enni Formation, which is dominated by a mixture of simple and compound lava flows commonly separated by minor volcaniclastic beds, including the widespread Argir Beds. In general, the interlava beds are tabular shaped and <1 to c. 6 m thick. Locally they thicken in depressions formed by the wedging out or differential erosion of underlying lava flow lobes. Connectivity may be caused by the wedging out of successive lava flows leading to the lateral merging of interlava beds or more rarely be hydraulically connected via conglomeratic fills of major channels. Lateral compartmentalization may be caused by the intersection of interlava beds by dykes, lava tubes, lava-filled channels or reverse faults.