Genesis and Expression of a Clinoforming Carbonate Ramp from a Geological and Geophysical Perspective

Jean-Yves Chatellier¹, Jeff Closson², and Anne Hargreaves^3
1Tecto Sedi Integrated Inc, Calgary, AB, Canada
²Talisman Energy Inc., Calgary, AB, Canada
³Canadian Stratigraphic Services 2000 Ltd, Calgary, AB, Canada

Progradation in a carbonate ramp is not always well expressed in seismic or in geological cross sections. Clinoforms in the Carboniferous Banff Formation (Alberta, Canada) have been studied in an integrated approach using log analysis, sedimentology and seismic data. The genesis and geometry of several clinoforms have been examined against their structural settings. Cutting descriptions from Canstrat have been used to better understand the sedimentology and lithologies above and below the clinoforming surfaces.

In the Western Alberta Basin, the Carboniferous Banff Formation is a prograding carbonate ramp with some very well developed clinoforms. Three main types of clinoforming surfaces have been recognized on wireline logs in association with transgressive shales, slump related chert units or catastrophic grain supported carbonate events. The seismic expression associated with the carbonate ramp has been tested against lateral facies variations.

Synthetic seismograms have been generated on many wells from a variety of clinoforms in order to determine if and when a progradation would be seen on seismic. A comparison between two geographically distinct clinoforms with apparently identical log expressions has outlined extreme differences in their potential to be seismically visible. The structural context favorable to recognizable clinoforming pattern is variable and the direction of progradation may vary dramatically especially when alternate fault activity is syndepositional. One example shows two successive clinoforming patterns at 90 degrees from each other within the Lower Banff.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas