AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
The Importance of Understanding Lithology and Depositional Environment-Rosebank Field, West of Shetlands, UKCS
(1) Chevron Upstream Europe, Aberdeen, United Kingdom.
The Rosebank field is located in the deepwater Faeroes-Shetland Basin, UKCS. The Palaeocene aged ‘Colsay’ reservoir sands were deposited during the onset of rifting of the North Atlantic Ocean and the structure developed at the juxtaposition of an easterly advancing volcanic system and the north-westward prograding Flett delta system. This was a time of hot, humid climatic conditions where high rainfall resulted in abundant river and delta systems interrupted by frequent volcanic episodes of erupting lava.
Siliciclastic sediments at Rosebank comprise fluvial and shallow marine sands and shales. Weathering of basaltic lavas resulted in a local source of volcaniclastic material ranging from breccias to mudstones. The volcaniclastic sediments are often directly in contact with the basalts but also mix and intercalate with the siliciclastic sediments. Correlation of the volcanic and siliciclastic intervals across the field is a key challenge and has been aided by biostratigraphy, basalt chemistry, log character and pressure data.
This talk presents the challenges involved in unravelling this complex mix of lithologies from log and core data into depo-facies, correlating these across the field and using this information along with appropriate analogues to assist in building a geological framework for reservoir modelling. It will also address the state-of-the art geostatistical techniques employed for population of facies and petrophysical characterization of the reservoir units.