Reservoir geometry influenced by high-frequency forced regressions within an overall transgression: Caroline and Garrington fields, Viking Formation (Lower Cretaceous), Alberta

584 well logs and 139 cores have been used to establish a two-part stratigraphy for the Viking Formation in the area of the Caroline and Garrington reservoirs, Alberta. The lower part consists of a northeastward-prograding coastal succession of offshore and shoreface storm deposits, capped in places by nonmarine facies. The upper stratigraphic unit consists of marine black shales with five tongues of coarse sandstone and conglomerate, each 1-3 m thick. Correlation of well-log and core cross sections suggests that these coarse tongues converge toward (and are interpreted to onlap) the underlying transgressive lag toward the southwest. The tongues are interpreted as extensions of the lower shoreface, formed during minor regressions interspersed with the main transgression. The coarse reservoir rocks appear to result from forced regressions, which are in turn controlled by high-frequency oscillations of sea level. -from Authors