3D seismic imaging of lower delta-plain beach ridges: lower Brent Group, northern North Sea

Abstract

Three-dimensional seismic reflection data are used to image littoral deposits within the lower Brent Group, northern North Sea. Seismic attribute maps within the unit indicate the development of parallel, highamplitude stripes up to 15 km in length, 50-100 m wide and spaced 150-200 m apart. In map view these features trend NE-SW to ENE-WSW and are arranged into 'sets' that display subtly different orientations. Well data in regions where these anomalies are well developed indicate pronounced anomaly-perpendicular thickness variations in sand-rich beach-ridge facies within the Etive Formation and coals and mudstones within the overlying Ness Formation. Based on these observations, the high-amplitude anomalies are interpreted as the seismic expression of coal-filled swales, whereas the adjacent zones of low amplitude are interpreted to represent the cores of sand-rich beach ridges. The geometry of beach ridges identified in the Etive Formation compares favourably with sedimentological and geometric data from modern beach ridges. The results of this study have implications for (1) the stratigraphic context and preservation of beach ridges, (2) datum selection when attempting stratigraphic correlations within the Brent Group, and (3) the exploration and production of hydrocarbons from beach ridge-type reservoirs.

Impact of top-surface morphology on CO2 storage capacity

“…Seismic attribute maps from the lower Brent Group in the North Sea (Jackson et al, 2010) revealed an extensive system of beach ridges preserved at the boundary between the shallow marine Etive Formation and the overlying Ness Formation suggesting that these features may be more frequent in the fossil record than previously envisaged. Key morphometric dimension of beach ridge systems used in our study are shown in Table 1.…”

Progradational and backstepping shoreface deposits in the Ladinian to Early Norian Snadd Formation of the Barents Sea

“…However, different explanations for the origin of the seismically imaged shoreface sets and beach ridge sets are proposed in different studies. In some cases, shore‐parallel linear amplitudes are argued to be caused by aeolian dune deposits on shoreface crests that alternate with lagoonal swamps, giving rise to amplitude contrasts (Jackson et al ., ). A second explanation is that acoustic impedance contrasts are generated between shoreface sandstones and chenier siltstones and mudstones that were extensive down depositonal dip (e.g.…”

“…Shoreface sets documented in the present study show a clear resemblance both to modern beach ridges and to ancient beach ridge deposits documented in previous studies (Dreyer et al ., ; Hadler‐Jacobsen et al ., ; Jackson et al ., ; McCullagh & Hart, ; Bourget et al ., ). However, different explanations for the origin of the seismically imaged shoreface sets and beach ridge sets are proposed in different studies.…”

Incipient mantle plume evolution: Constraints from ancient landscapes buried beneath the North Sea

“…Second, although mapped as a dendritic drainage network by Underhill [], remapping of the southeast quadrant indicates that these features tend to be unconnected and subparallel to the paleo‐coastline. They are more likely beach ridges [e.g., Jackson et al ., ]. Finally, remapping the top of the Dornoch Formation indicates that it possesses no coherent or connected drainage network.…”