REV Modelling of the Triassic Judy and Joanne Sandstones in the Culzean Field, CNS, UK

The Culzean field is a high pressure - high temperature field located within block 22/25a of the Central North Sea, UK, and contains the Middle Triassic Judy Sandstone and the Middle to Upper Triassic Joanne Sandstone fluvial reservoir units of the Skagerrak Formation. While the sedimentology of the Skagerrak has been studied in detail, it is clear there are a range of heterogeneities that will often be missed when creating reservoir models, particularly when the models are upscaled for flow simulations. This work investigates the scales of heterogeneity that could affect reservoir production by using a mini-permeameter study and multi-scale reservoir modelling approach. Detailed sedimentological analysis of the Judy and Joanne sandstones suggests that the fluvial deposits of these two members were formed by two separate fluvial systems. Results from the mini-permeameter study show a 47% reduction in horizontal permeability, a 78% reduction in vertical permeability, and a 39% difference in the production cumulative as a result of including the small-scale heterogeneities observed within the core. This work highlights the importance of a multi-scale reservoir modelling approach to ensure small-scale heterogeneities are included in the models to more accurately predict production profiles.