Chemostratigraphy in Field Appraisal and Reservoir Correlation: Implications from Outcrop Analogue Study in Submarine Slope Channel Systems (Tabernas Basin, Spain)

Aehnelt, Michaela ¹; Worden, Richard H.¹; Hill, Stephen ²; Flint, Stephen S.¹; Hodgson, David M.¹; Canham, Andrew ^2
1 Earth and Ocean Sciences, University of Liverpool, Liverpool, United Kingdom.
² Integrated Reservoir Solutions Ltd. (IReS), Ellesmere Port, United Kingdom.

Chemical stratigraphy has become a widely used technique in the oil industry for characterising, interpreting and stratigraphic zoning of sedimentary successions. This technique extracts and makes use of information on the ratios of a range of different elements in the sedimentary rock, especially with regard to depositional facies and environment, sediment provenance, mineralogical characterisation and diagenetic studies, and in detecting stratigraphic marker horizons. However this technique lacks integration with existing stratigraphic correlation methods and the aim of this study is to investigate the nature of chemically defined stratigraphic correlations using exceptionally exposed outcrops, where the physical stratigraphic correlation is known precisely.

Geochemical and mineralogical studies in sandstone and mudstone strata from exposures of a Tortonian submarine slope channel system in the Tabernas basin of southern Spain were undertaken to assess the accuracy of the chemostratigraphic technique. Data were obtained from sampling of vertical sections at outcrop to mimic wells, covering axial to marginal settings at variety of scales down the course of this ancient exhumed deep marine channel complex. The objective of this case study is to determine the controls on geochemical variations stratigraphically and along the channel, and the distinctions in the chemical signature between separate channel units within the channel complex and between the channel complex and the bioturbated marly sediments in which it is encased.

The data set obtained from this excellently exposed reservoir analogue demonstrates the relationships between the chemical and mineral stratigraphy based on the element and mineral distributions determined by XRF and XRD, and the known physically mapped architecture. This enhances our understanding of how chemical trends follow depositional ones by interpreting the exact reasons why certain elements are distributed in certain ways within the sediment dispersal system.

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009