Reservoir quality and its relationship to facies and provenance in Middle to Upper Jurassic sequences, northeastern North Sea

Abstract

AbstractClose relationships are demonstrated between reservoir quality, lithofacies, provenance and burial history in the Jurassic Brent and Viking Groups in the Norwegian North Sea. Porosity and permeability are strongly and systematically related to the initial texture and composition of the sandstones. Porosity variations are related to the amount of compaction, which is more severe in matrix-rich than in clean facies, and quartz cementation, which is most important in clean facies. Permeability variations are related to porosity and facies-controlled variations in grain size, and abundance and texture of intergranular fines. Illitization of early diagenetic kaolins require K, which is derived mainly from dissolution of K-feldspar. Sediments were sourced from K-feldspar- poor provenances during the maximum progradation of the Brent Group, and sandstones deposited at this time are less exposed to illitization and have better permeability at deep burial than reservoir sandstones that initially contained more K-feldspar.