Hummingbird Structure of Southeast Saskatchewan

Abstract

ABSTRACT Saskatchewan's first Devonian oil pool was discovered September, 1966 at Hummingbird, 45 mi southwest of Weyburn, Saskatchewan. The Hummingbird structure, located on the northwest flank of the Williston basin, is domal in nature and covers approximately 1 sq mi. Oil production is from two zones. The Ratcliffe Member of the Mississippian Charles Formation produces from an average of 49 ft in an algal and bioclastic limestone. The Devonian Birdbear Formation produces from an average of 56 ft in a fine-crystalline, vuggy dolomite. The Hummingbird structure is not diastrophic in nature. Rather, it is a sedimentary structure resulting from multiple-stage salt solution and collapse. Recurring local solution of Middle Devonian Prairie Evaporite salt during Late Devonian and Early Mississippian time resulted in collapse of overlying strata and deposition of compensating thicknesses of Souris River, Duperow and Bakken sediments. Between Mississippian and Cretaceous time, solution of Prairie Evaporite salt in the surrounding area caused collapse of all post-Prairie Evaporite beds. The extra Souris River, Duperow and Bakken strata at Hummingbird created the structure. Vertical migration of formation waters along a high-angle fault is suggested as the cause of the local salt solution at Hummingbird.