Triassic Research Group

The Triassic Phase 3 project builds on two successful earlier phases and comprises a Joint Industry Research Project sponsored by BP, Total, JXNippon, Neptune Energy and CNOOC. It is focussed in the UK sector of the Central North Sea and will examine the structural and halokinetic controls on sandstone body distribution, with enhanced correlation and provenance techniques providing inputs to reservoir modelling studies.

Summary of Phase 2: The work combined biostratigraphic, heavy mineral and sedimentological datasets to deliver an improved understanding of the Triassic succession in the UK CNS. In particular, the pre-existing correlation framework was revised and enhanced providing improved spatial and temporal resolution for more confident correlation of mudstone and sandstone units. At a basin scale the location of sediment input points was defined and a series of large distributive fluvial systems sourced from the Scottish and Norwegian landmasses mapped. These coalesce to form an axial system in the centre of the basin. At field and block scale discrete sediment packages were mapped at a sub-member scale and areas where these units overlap/interfinger (likely represent individual channel-belt avulsion lobes) have been identified. Preliminary work suggests some diachroneity is present within the members and that simple correspondence between litho-, bio- and chronostratigraphic methods is unlikely with increasing biostratigraphic resolution.

Revised biostratigraphic correlation across the UK sector of the Central North Sea, highlighting the presence of a possible intra-Carnian unconformity (from Burgess et al 2020).

Schematic depositional systems produced using palaeocurrent measurements, facies analysis, heavy mineral analysis and DFS models. Judy Sandstone Member systems show an axial DFS pinned in the Central Graben region by lateral DFS sourced from Scottish and Fennoscandian highlands. The Joanne Sandstone Member systems show an increase in dominance of the Fennoscandian eastern-sourced DFS and a decrease in western-sourced DFS. This leads to the Fennoscandian DFS dominating the axial DFS. FMH, Forties Montrose High; FGS, Fladen Ground Spur; HH, Halibut Horst. From Gray et al. 2020

Publications include:

R. Burgess, D. Jolley, A. Hartley 2020 Stratigraphic palynology of the Middle–Late Triassic successions of the Central North Sea. Petroelum Geoscience, 10.1144/petgeo2019-128

Gray, E., Hartley, A., Howell, J., 2020. The Influence of Stratigraphy and Facies Distribution on Reservoir Quality and Production Performance in the Triassic Skagerrak Formation of the UK and Norwegian Central North Sea. Geological Society, London, Special Publications 494 Gray et al  https://doi.org/10.1144/SP494-2019-68

The FORCE Triassic Joint Industry Project is sponsored by: Neptune Energy, Spirit, Mol Norge, Vår Energie, DNO, AkerBP and WintershallDea

Project Outline:

Triassic reservoirs form one of the last remaining exploration targets and an important secondary objective across much of the UK and Norwegian North Sea. However poor seismic resolution, lack of age control and reliance on lithostratigraphic correlation schemes have hindered attempts to understand and predict these reservoirs. Utilising a multidisciplinary approach including sedimentology, interpretation of seismic reflection data, biostratigraphy and heavy mineral analysis, coupled with AI and machine learning applied to Triassic strata of the Norwegian sector a new, high resolution stratigraphic scheme will be developed. Work will combine palynology from mudstones and heavy mineral, geochemical and detrital zircon data from sandstones. These datasets will be used to establish the highest available temporal and spatial framework for the North Sea Triassic to date. Utilising this framework, a core-based sedimentological scheme combined with analysis of seismic data to identify structural and halokinetic controls will novel neural network methodologies for facies identification in uncored intervals will allow regional mapping of discrete fluvial depositional systems.

For further information please contact Professor Adrian Hartley.