The structural evolution of the Snorre Field and surrounding areas

Abstract

The Snorre Field is located on the Tampen Spur, Northern Viking Graben between 61°N and 62°N. Main structural elements are large, westerly tilted fault blocks. The Snorre Structure, one of the largest fault blocks in the East Shetland Basin, extends across Block 34/7 into Block 34/4. The Snorre Fault Block includes the Snorre Field, Tordis Field and the Vigdis Field oil discoveries. Major oil discoveries have so far been made in the Brent Group, the Statfjord Formation and the Lunde Formation. Discoveries have also been made in the Upper Jurassic and Paleocene. Upper Jurassic stratigraphic traps are the main target for further exploration in the area. The westerly rotated fault blocks on the Tampen Spur are delineated by NNE–SSW- to NE–SW-trending faults. From west to east, these are the Murchison Fault, the Outer Snorre Fault, the Southern Snorre Fault and the Inner Snorre Fault. Other faults recognized are the E–W- and SE–NW-striking cross-faults dividing the elongated fault blocks into minor compartments. The N–S-striking faults are common in the Snorre area. The number of these faults decreases towards the north. The Snorre Escarpment is the surface expression of the major Inner Snorre Fault representing the eastern border fault of the Snorre Fault Block. Two major rifting episodes are recognized in the area. In the thermal subsidence phase following the late Permian to early Triassic rifting, large amounts of sediments of the Teist-, Lomvi-, Lunde-, Statfjord Formation, Dunlin- and Lower Brent Group were accumulated. A second major rifting episode resulted in intense fault activity from the early Bathonian to the late Kimmeridgian. Two major pulses of increased tectonic activity are recognized in the second rift episode. In the north, in the Zeta area, there is indication of late Jurassic lateral movements. Late Jurassic faulting, block rotation and footwall uplift, combined with Jurassic to Cretaceous subsidence, make the Snorre Fault Block of the Tampen Spur a very pronounced structural high in the area.