Abstract

The Mississippian Turner Valley Formation consists of 300 feet of echinoderm and bryozoan carbonates that were deposited as a diachronous megafacies accreting basinward. The cyclic Turner Valley sediments record accumulation in a series of megabars and troughs whose bathymetric amplitude decreased shoreward.

Typical reservoir rock in the Turner Valley Formation, as exemplified by the Whiskey Creek field, consists of partially dolomitized packstone or wackestone with intercrystalline matrix porosity and vuggy porosity due to leaching of allochems and patches of matrix. At Whiskey Creek, dolomitization and leaching are more complete in the top than in the base of the formation. Regionally, both decrease in intensity southwest-ward from the subcrop. A further basinward reduction in reservoir development occurs because of a parallel decrease in packstones and wackestones and an increase in grainstones which have been tightly calcite-cemented. This facies change may be due to a steepening shelf-to-basin profile, which is reflected in a basinward thickening of the Banff Formation and by disappearance of the Shunda lagoonal megafacies as the Turner Valley merges with the Pekisko to become the Livingstone Formation.