Tertiary erosion magnitudes in the East Midlands Shelf, onshore UK

Abstract

Sonic velocities from the Upper and Middle Chalk, the Kimmeridge Clay, the Lias and the Bunter Sandstone were used to quantify apparent erosion (i.e. amount of missing section) in the Welton-1 and Cleethorpes-1 wells of the East Midlands Shelf, onshore UK. Apparent erosion was determined with reference to sonic velocities in 150 wells the UK Southern North Sea area. Apparent erosion at Cleethorpes-1 is estimated as 1.4 km (from the Kimmeridge Clay, Lias and Bunter Sandstone) and 1.6 km (from the Upper and Middle Chalk), and at Welton-1 as 1.6 km (from the Bunter Sandstone) and 1.7 km (from the Lias). The consistency of results from the different units analysed increases confidence in the results with respect to compaction studies based on a single stratigraphic unit. Estimates of missing section in this study are generally greater than those previously published for the East Midlands Shelf, but they are consistent with recent estimates from apatite fission track analysis.