AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Geophysical, Petrophysical and Sedimentological Characterisation of Paleocene Submarine Fan Systems UK Central North Sea
(1) Geology and Petroleum Geology, University of Aberdeen, Aberdeen, United Kingdom.
(2) School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom.
(3) Shell UI Europe, Aberdeen, United Kingdom.
The Paleocene submarine fans of the UK Central North Sea are important petroleum reservoir units recording the cylic input of sand-rich turbidite flows into the post-rift Central Graben basin. Each of these cycles (Maureen, Andrew and Forties) have associated hydrocarbon production with the youngest Forties sands being the most prospective (for example Nelson, Forties and Pierce fields). Thanks to this regional prospectivity, there is an extensive associated dataset of 3D seismic, well logs and core material. The provision of these datasets by Shell UI Europe has enabled a regional-scale re-evaluation of these deposits. Observations from seismic, core and well log analysis are used to map the reservoir quality and seismic stratigraphy of the Paleocene Maureen and Andrew sandstone members and advance our understanding of the syn- and post-depositional dynamics within the submarine fans.
The use of regional seismic data allows observations to be made about the extent, thickness, net to gross, bathymetric interaction and temporal evolution of the submarine fans. Observations from seismic data benefit greatly from correlation with core analysis and an extensive well database. Core from 21 wells has been studied to evaluate the types of facies present and how these relate to bed connectivity, grain size distribution and porosity/permeability trends. Furthermore, integration of a regional well database (containing ~350 wells) allows for large-scale mapping of formation thicknesses and reservoir quality. In turn, this has enabled seismically derived maps to be ground-truthed enabling a more quantitative approach to seismic attribute-based reservoir mapping.
The integration of these observations enables powerful interpretations to be made with both academic and industrial applications. Examples are presented of potential scientific advances including clarification of our understanding of the spatial and temporal evolution of the submarine fans from source to sink. Observations are made of the impact of basin geometry and salt-induced bathymetric variations on the distribution of reservoir properties as well as potential changes in the source area and the validity of previous models. Maps of sediment distribution and reservoir quality allow industry workers to consider the remaining prospectivity of these intervals. It is hoped that this study will prove valuable to workers in both the Central North Sea and global deep water sedimentology.