ABSTRACT This field guide presents a one-day excursion in Prince George’s County, Maryland, USA, and documents the transition across the Cretaceous-Paleogene boundary by examining sediments from the upper Maastrichtian of the Severn Formation to the Paleocene sediments of the Brightseat and Aquia formations. Emphasis is placed on understanding how differences in depositional character and lithostratigraphy are related to changes in both microfossil and macrofossil assemblages. Particular attention is given to the difficulty in distinguishing Upper Cretaceous sediments from lower Paleocene sediments in the field, a problem that has traditionally led to misrepresentation of the distribution and thickness of these units and their correlation on a regional scale. Regarding the Late Cretaceous geology, the guide presents information on the lithology and microfossil biostratigraphy of the Severn Formation, which consists predominantly of silty quartz sand, with less than 5% clay. These sediments are placed in calcareous nannofossil Zone CC25a, suggesting an early late Maastrichtian age. Low abundances of planktic foraminifera combined with sedimentological evidence suggest deposition most likely occurred in a middle neritic environment. Macrofossils in the outcrops along the field trip consist primarily of fragmented bivalve mollusk and cephalopod shell material. A hiatus of ~5 m.y. separates the Cretaceous sediments from the overlying Paleocene deposits. As for the Paleocene geology, the guide presents information on the Brightseat and Aquia formations. The Brightseat represents early Danian age deposition and consists of clayey, silty sand at the base that grades upward into a silty sand. Glauconite is present at <5% throughout the formation in outcrop. Sediments of the Brightseat Formation are placed in calcareous nannofossil Zone NP3. Macrofossils are limited to small bivalve fragments that are scattered throughout. A hiatus representing ~3 m.y. separates the Brightseat from the overlying Aquia Formation, which is Selandian to Thanetian in age and consists of a glauconite-rich (~10%–20%), silty sand with common to abundant macrofossils, including both fragmented and complete gastropods and bivalves.

Abstract The Brechin Field was discovered by Paladin Resources in 2004. The reservoir is the Paleocene Forties Sandstone Member, with oil trapped in a small dip closure. The prospect was identified as a bright anomaly on a fluid volume processed as part of a 4D survey. However, the anomaly was not consistent with rock physics modelling, and an earlier processed version of the baseline 3D survey showed the opposite response to the 4D datasets. It was established that the fluid anomaly on the 4D data resulted from constructive interference between reflections from the oil–water contact and from top reservoir. Thus, both versions of the data were responding to the presence of hydrocarbons. The discovery well, 22/23a-7, encountered 137 ft of gross oil-bearing reservoir. Without testing or further appraisal, the field was developed in 2005 with a single production well tieback to the Arbroath platform, via the production manifold at Arkwright Field. Brechin is now operated by Repsol Sinopec Resources and cumulative production to mid-2018 was 4.4 MMbbl. Seismic attributes and well-developed reservoir understanding from neighbouring analogue fields permitted the necessary de-risking of hydrocarbon presence, recovery and volumetric uncertainty, to permit the development of an otherwise economically marginal resource.

Abstract The Huntington Oil Field is located in Block 22/14b in the Central Graben of the UK Continental Shelf. The reservoir is the Forties Sandstone Member of the Sele Formation, and oil production is from four production wells supported by two water-injection wells, tied back to the Sevan Voyageur FPSO (floating production storage and offloading unit). Initial estimates of oil-in-place were c. 70 MMbbl and the recovery factor at the end of 2017 after 4.5 years of production was 28%, which reflects the weak aquifer and poor pressure support from water injection. The Huntington reservoir is part of a lobate sheet sand system, where low-concentration turbidite sands and linked debrites are preserved between thin mudstones of regional extent. Within the reservoir, three of the thicker mudstone beds can be correlated biostratigraphically on a regional basis. This stacked lobate part of the system sits above a large-scale deep-water Forties channel that is backfilled by a system of vertically aggrading channel storeys. Despite the relatively high net/gross of the reservoir, the thin but laterally extensive mudstones in the upper (lobate) part of the system are effective aquitards and barriers to pressure support from water.

Abstract The Kraken and Kraken North fields lie in the UK Continental Shelf Block 9/2b on the East Shetland Platform. Hydrocarbons are stratigraphically trapped within Heimdal Sandstone Member of the Lista Formation. The fields lie at around 3900 ft true vertical; depth subsea and the oil is heavy (13–15°API) and viscous. The field is developed via a waterflood scheme with long horizontal production and injection wells, alternating across the field. To date, 21 development wells have been drilled, with further wells planned. Reservoir quality is extremely good with porosity around 36% and permeabilities in the range of 2–10 D. The field is produced via the Armada Kraken floating production storage and offloading vessel. Developed stock tank oil originally in place is in the region of 400 MMbbl, with further currently undeveloped resources to the west of the field.

Abstract The Rosebank Field is located primarily in Block 213/27a in the Faroe–Shetland Basin, c. 130 km west of the Shetland Islands in water depths of c. 1100 m (3600 ft). Hydrocarbons are trapped within an elongate, SW–NE-trending four-way anticlinal structure. The principal Colsay Sandstone Member reservoir consists of several vertically stacked, Late Paleocene to Early Eocene fluvial and deltaic reservoirs separated by volcanic sequences. Well log and core data indicate that reservoir quality is high, with porosities in the range of 19–23% and average permeability of c. 3 D. Oil quality is also high, with average oil gravity of 37°API and in-situ viscosity of c. 1 cP at a mean reservoir temperature of 175°F. The field holds a substantial resource and is currently under evaluation for development.

Abstract This Special Report comprehensively describes the stratigraphy and correlation of the Tertiary (Paleogene-Neogene) rocks of NW Europe and the adjacent Atlantic Ocean and is the summation of fifty years of research on Tertiary sediments by Chris King. His book is essential reading for all geologists who deal with Tertiary rocks across NW Europe, including those in the petroleum industry and geotechnical services as well as academic stratigraphers and palaeontologists. Introductory sections on chronostratigraphy, biostratigraphy and other methods of dating and correlation are followed by a regional summary of Tertiary sedimentary basins and their framework and an introduction to Tertiary igneous rocks. The third and largest segment comprises the regional stratigraphic summaries. Regions covered are the North Sea Basin, on shore areas of southern England and the eastern English Channel area, the North Atlantic margins (including non-marine basins in the Irish Sea and elsewhere) and the Paleogene igneous rocks of Scotland.