HOWELL, John A., University of Liverpool, Liverpool, England; H. E. EDWARDS and G. WILLIAMS, University of Keele, England; and A. BECKER, P. TURNER, and A. SEARL, University of Liverpool, Liverpool, England

ABSTRACT: Controls Upon Hydrocarbon Reservoir Evolution Within the Rotliegende Group: A Fully Integrated Regional Study

The collection of a large database, in conjunction with new understandings of sedimentology and structural controls upon diagenesis, has enabled the detailed mapping of the factors that control the distribution of hydrocarbon reservoirs within the Rotliegende Group of the United Kingdom southern North Sea. The results of this regional study incorporate detail previously confined to field scale studies.

High resolution sedimentological and stratigraphic studies (4 km of core) have resulted in a twelve-fold subdivision of the Rotliegende Group based upon the recognition of climatically

driven depositional cycles. These illustrate a progressive basin expansion controlled by the distribution of buried lower Paleozoic granites and post-Vanscan topography. This model incorporated with mapping of facies distribution has been used to document the distribution of potential reservoir rocks.

Detailed diagenetic work has documented the distribution of all the principal mineral phases within the basin. Integration with structural studies has revealed the role of fractures for introducing fluids to, and compartmentalizing reservoirs has led to significant understanding of the source and transport mechanism for the pore-occluding diagenetic phases. Regionally, an understanding of burial and inversion events has demonstrated that the distribution of clays, particularly permeability destroying illite, is controlled by both burial depth and a source of reactants.

Combination of sedimentological and diagenetic aspects has enabled the production predictive maps for the area. This, combined with the structural work, has highlighted the importance of timing of hydrocarbon migration in relation to reservoir structuration, particularly in areas away from the main Sole Pit source kitchen.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.