Exploration statistics of North Sea plays in UK–Norway–Denmark

Published on 2020-05-28T11:32:26Z (GMT) by
The central–northern North Sea region represents one of the richest and most diverse petroleum basins in the world. This paper presents an analysis of the historical results of exploration in the Central Graben, Outer Moray Firth and Viking Graben, plus surrounding regions, including West of Shetlands. The richness and maturity of the main late Jurassic source rock account for almost 100 billion barrels of oil equivalent (boe) recoverable resource in the three rift arms. Within a contiguous area of 100 000km<sup>2</sup>, 29 different proven part plays (area-confined, deposition-specific stratigraphic intervals or play segments) have been analysed in detail. Here 78.1 billion boe recoverable resource occurs in 717 discoveries ranging in reservoir age from Triassic to Eocene. The most prolific plays in terms of total resource found are Mid-Jurassic paralic sandstones (in the Viking Graben), Upper Cretaceous chalk (in the Central Graben) and Paleocene turbidite sandstones (in all three rift arms). The average discovery rate (historical chance of geological success) across all the plays is 44% with a relatively low variance. No significant improvement is seen in success rate over the last 50 years, despite increased well density, knowledge and huge advances in geophysical data. 404 of the discoveries are commercial fields representing 57% of all discoveries but the rate has decreased to 33% over the last 10 years, as average discovery sizes have decreased significantly. Discovery size is highly variable (10–>600 MMboe) but the historical average is 114 MMboe, a world class value. Dividing discovery recoverable resource size by footprint area produces a useful measure of reservoir yield, MMboe/km<sup>2</sup>, and the median value for the different part plays varies from 1.3 MMboe/km<sup>2</sup> for an Eocene turbidite to 5.3 MMboe/km<sup>2</sup> for a Jurassic turbidite. From a global perspective, the North Sea is not only unusual in the volume of petroleum, diversity of reservoirs and size of discoveries but also for its number of overlapping part plays and for the fact that the largest volume of total resource is found in reservoirs older than the source rock, syn-rift sandstones having been charged from an end-of-rift marine shale.

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Quirk, David G.; Archer, Stuart G. (2020): Exploration statistics of North Sea plays in UK–Norway–Denmark. Geological Society of London. Collection. https://doi.org/10.6084/m9.figshare.c.4996625.v1