uGeneral setting

uFigure captions

uDepositional environments

uApplication

uReferences

uGeneral setting

uFigure captions

uDepositional environments

uApplication

uReferences

uGeneral setting

uFigure captions

uDepositional environments

uApplication

uReferences

Figure Captions

Figure 1. Location map of Sleipner Field, Southern Viking Graben, North Sea.

Figure 2. Opening and drowning of the Viking Graben in Mid Jurassic (palaeogeographic maps from Cope et al, 1992).

Click to view sequence of palaeogeographic maps.

Figure 3. Facies architecture panel of the aggrading to retrograding part of the Hugin Formation, Sleipner West Field.

Figure 4. Panel of upper Hugin Formation (from Figure 3), with division into regressive and transgressive depositional sequences, as an illustration of the concept of volumetric partitioning.

Click to view sequence of Figures 3 and 4.

Depositional Environments and Sequences

From 26 cored wells, 17 facies associations have been identified and grouped into 6 genetic depositional sub-environments: coastal plain fines, tidal channel fill and bars, tidal flat, prograding mouthbars, shoreface, and offshore mudstones. Interpretation of facies associations in uncored intervals was followed by a detailed well-to-well correlation based on both sedimentological and biostratigraphic evidence. The correlations reveal that the Hugin Formation consists of 8 transgressive/regressive sequences where the transgressive parts of sequences consists of tidal channel fills, tidal bars, tidal flats and coastal plain fines deposits whereas the regressive part consists of coastal plain fines in the form of palaeosols, with associated prograding mouthbars and shoreface deposits. Offshore mudstones occur in both parts as the distal component of the depositional systems (Figure 3). 

The regressive and transgressive parts of sequences have characteristic thickness trends (Figure 4). The regressive segments of a sequence increase in thickness basinward until a point where the sandstone gives way to offshore mudstone of the Heather Formation. The transgressive segments of the sequences have a minimum thickness in basinal areas and increase in thickness in the landward direction until a point where the sandstone gives way to shales and coals of the continental Sleipner Formation. These thickness trend observations can be explained when considering mass-balance in the depositional profile (Shanley and McCabe, 1994; Willis, 1997). Regression occurs as a result of lack of accommodation space and excess in sediment supply in a landward position that forces the coastline to prograde seaward, so the majority of sediments are trapped in a seaward position. During transgression, the majority of sediments are trapped in a landward position due to an increased accommodation space in that location.

Application

Application of this concept to interwell areas provides a powerful predictive tool for the thickness and facies type of Hugin Formation sandstones.

References

Cope, J.C., Ingham, J.K. & Rawson, P.F., (1992). Atlas of palaeogeography and lithofacies. The Geological Society of London Memoir No. 13, 155 p.

Shanley, K.W., and McCabe, P.J., (1994). Perspectives on the sequence stratigraphy of continental strata. Report of a working group at the 1991 NUNA Conference on high resolution sequence stratigraphy: AAPG Bulletin, v. 78, no. 4, p. 544-568.

Thomas, D. W., and Coward, M. P., (1996). Mesozoic regional tectonics and South Viking Graben formation: evidence for localised thin-skinned detachments during rift development an inversion. Marine and Petroleum Geology, v. 13, no. 2, p. 149-177.

Willis, B.J., (1997). Architecture of fluvial-dominated valley-fill deposits in the Cretaceous Fall River Formation. Sedimentology, v. 44, p. 735-757.

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