--> Abstract: Chemostratigraphy and Its impact on Exploration and Development of Upper Carboniferous Gas Fields in the Southern North Sea, by Tim J. Pearce, John H. Martin, Diana Cooper, and David Wray; #90039 (2005)

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Chemostratigraphy and Its impact on Exploration and Development of Upper Carboniferous Gas Fields in the Southern North Sea

Tim J. Pearce1, John H. Martin2, Diana Cooper3, and David Wray4
1 Chemostrat Ltd, Powys, United Kingdom
2 Chemostrat Ltd,
3 Zawiyah Associates Ltd, London, United Kingdom
4 University of Greenwich, Chatham Maritime, United Kingdom

Important gas reservoirs lie in Upper Carboniferous coal measures and red beds of the Southern North Sea. The red beds of the Boulton/Ketch Formations are >1000ft-1500ft thick and notoriously difficult to correlate, with poor internal seismic definition, repetitive e-log signatures and poor palynological preservation. In the underlying coal measures (Westoe Coal and Cleaver Formations), seismic resolution and palynological recovery are improved, but stratigraphic correlation remains problematic due to coal ‘pinch out' and the lack of diagnostic taxa in certain intervals. However, the use of chemostratigraphy on core and cuttings from over 50 wells from numerous fields in Quadrant 44 and 49 (UK sector) and Blocks E, F and K in the Dutch sector has resulted in the establishment of a robust independent hierarchical high resolution stratigraphic correlation scheme throughout the red beds and coal measures.

This paper presents a series of correlative chemostratigraphic reference sections for the Westoe Coal, Cleaver, Ketch and Boulton Formations. This chemostratigraphic zonation is based on changes in provenance, climate regime and depositional environment (well drained and poorly drained palaeosols, marine bands, lacustrine flooding intervals, coal swamps) and the recognition of key tonstein bearing intervals. Chemostratigraphic packages can be correlated between fields and are used to constrain seismic correlations to highlight potential exploration targets, whereas a high resolution chemostratigraphic units and subunits are correlative on a field scale and are used to enhance reservoir correlation during reservoir developments in fields such as Boulton, Schooner, Tyne, Ketch and Topaz.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005