Reconstruction of heterogeneous reservoir architecture based on differential decompaction in sequential re-burial modelling

A new methodology for robust, high-resolution correlation of reservoir sandstones in highly compactable depositional sequences is proposed. Quantitative sequential re-burial modelling has been successfully applied on real data from seven wells covering the heterogeneous fluviodeltaic Åre Formation in the Heidrun Field, offshore mid-Norway. The methodology is based on ten interpreted lithofacies classes derived from core descriptions and wireline logs signatures, in addition to interpreted sequence stratigraphic surfaces, i.e. flooding surfaces. Analysis of decompacted sedimentary columns, with emphasis on studies of shallow compaction effects tied to uniquely calculated compaction curves, has revealed several new correlatable horizons within the Åre Formation. These include laterally extensive coals and several laterally correlatable fluvial sandstones enabling a reinterpretation of parts of the Åre stratigraphy. The results from the present study demonstrate the benefits of correcting for the effects of differential compaction in well-to-well correlation of heterogeneous reservoirs comprising highly compactable sediments. The methodology outlined here has widespread applicability to other stratigraphic successions and could potentially help in the correlation of highly compacted sediments in the subsurface.