The Knarr Field is located in the northern Norwegian North Sea, beyond the Brent Group delta fairway. Knarr was discovered in 2008 with the Jordbær well, additional resources were added to the field in 2011 with the successful Jordbær Vest well. The field extends over an area of approximately 20 km2. The original oil in place is estimated to be 26 MSm3 (163 MBBL). The reservoir is the Late Pliensbachian Cook Formation and its current burial depth is approximately −3700 m true vertical depth subsea (TVDSS). In Knarr, the Cook Formation is split into five sandstones that are separated by four shale intervals which can be correlated across the field. The three lower sands (Lower Cook) are interpreted to have been deposited in a tidally-dominated environment, while the upper two sandstones (Upper Cook) were deposited in a wave-dominated shallow-marine setting. The reservoir properties of the Cook Formation in the Knarr area are remarkably good for a reservoir at this depth, with porosities up to 28% and permeabilities in excess of 1 D. The good reservoir properties are the result of grain-coating chlorite, which has inhibited diagenetic quartz development. The field is developed with three oil producers and three water injectors produced via a floating production storage and offloading vessel (FPSO). First oil was achieved in March 2015.

Interpretation of 2D seismic reflection data combined with correlation of five wells in the southern part of the Central Irish Sea Basin show a NE‐SW trending graben, whose bounding faults are considered to be reactivated lineaments of Precambrian age. The basin‐fill comprises mainly Carboniferous and Triassic successions, with localised and thin occurrences of Lower Jurassic and Tertiary rocks, all of which are unconformably overlain by Quaternary sediments. Due to poor data quality, the structural evolution of the area during the Late Palaeozoic is poorly understood. During the Triassic, the basin was subjected to thermal subsidence with a phase of minor uplift in the Anisian. The major phase of extension in the basin took place during the ?Middle ‐ Late Jurassic and had a NW‐SE orientation. Subsequent Late Jurassic sinistral shear along the NE‐SW trending basin bounding fault is suggested to have taken place, giving rise to a series of north‐south intra‐basinal faults. The present‐day structure of the basin is a broad anticline, inherited from a Cretaceous ‐ Early Tertiary compressional phase. During the Palaeocene the area was subjected to regional uplift, followed by minor extension along the NW boundary fault during the Eocene ‐ Oligocene. A Late Tertiary phase of transpression is postulated to have occurred, which inverted north‐south trending faults and folded the base‐Tertiary unconformity.

No abstract

Well data analysis and the interpretation of 2D and 3D seismic reflection data provide valuable insights into the distribution and timing of fault activity within the Central

No abstract