Three shelf sandstone cores from western Alberta are discussed in terms of lithology, bedding types, log character, and processes of deposition. Two of the cores are Cardium cores, one each from Ricinus and Caroline Fields. A single Viking Sandstone core from Stettler Field is discussed.
The general geology of the Cardium field at Ricinus is given in Walker (this volume: “Upper Cretaceous (Turonian) Cardium Formation, Southern Foothills and Plains, Alberta”). The Cardium Formation is a 50-100 m thick sandstone within the dominantly shaley Alberta (= Colorado) Group, and is Turonian (U. Cretaceous) in age. The geologic setting at Ricinus is summarized in Walker (this volume, Figs. 1, 12, 14, 15, 18); the field is basically a channel fill, the channel being at least 45 km long, 4-5 km wide (before palinspastic reconstruction), and 20-40 m deep. Ricinus sits on top of the junction between the Plains (no deformation) and Foothills (multiple imbricate thrusts); in some wells the sandstone is repeated up to about 6 times.
The Gulf Ricinus 13-26 well is in the northern part of Ricinus Field, which is structurally simpler than the southern part. The gamma-sonic log (Fig. 1) and SP-resistivity log show the sand to be abrupt and sharp-based; the top is also abrupt. Serrations in the gamma ray indicate either thin mud-stone partings, or zones of ripped-up mud clasts (e.g., 9011.5, 9017, 9019, 9020 feet).
As can be seen in the photographs of the slabbed cores (Fig. 2, A-D) the base of the sandstone (9023.6 feet)
Figures & Tables
Shelf sandstone reservoirs are becoming a more and more common exploration target. What they are, how they may be characterized, and how they differ from shoreline and deep-water deposits in the subject of this publication. Shelf sands and sandstone reservoirs are among the more poorly understood types of sandstones. Continental, shoreline and deep water sandstones have all been studied in much more depth than have shelf sands and sandstones. However, during the last fifteen years significant progress has been made in understanding shelf sands and sandstones. Studies of modern sediments have allowed us to understand many of the depositional processes active on the shelf. This book is intended to be an up-to-date summary of shelf processes and products. The papers are intended for those new to shelf sands and sandstones as well as the shelf specialist.