--> ABSTRACT: Discrimination of Triassic and Jurassic Reservoir Sequences Using Whole Rock Chemical Data and Chemostratigraphy in the North Sea Central Graben, by S. M. Habesch, R. Bobolecki; #91020 (1995).

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Discrimination of Triassic and Jurassic Reservoir Sequences Using Whole Rock Chemical Data and Chemostratigraphy in the North Sea Central Graben

S. M. Habesch, R. Bobolecki

A major chemical study of cored Triassic and Upper Jurassic sandstone sequences from seven wells in Blocks 23/26, 23/27 and 7/11 has demonstrated that the two stratigraphical groups can be reliably discriminated by major and trace element data. The chemical database collected by inductively coupled plasma (ICP) spectroscopy, included all the major oxides and 20 trace elements including REE. A programme of multivariate discriminant function analysis (DFA) was used to separate the two stratigraphic groups statistically with 1 misclassification in 20. The most powerful elements in discrimination were Na2O, TiO2, Y, Zr, Er and Cu. Multivariate chemical signatures have been established for both the Triassic and Upper Jurassic sequences in the Central Grab n. Additionally, chemical signatures attributed to Triassic reworking are also recognised within some of the Upper Jurassic lithologies.

The ICP chemical database combined with DFA modelling has proved to be a very important tool in stratigraphic studies in the Central Graben, especially where there is little biostratigraphical data, and is currently used in identification of unconstrained reservoir sequences in this region.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995