Structural Setting and Validation of Direct Hydrocarbon Indicators for Amauligak Oil Field, Canadian Beaufort Sea (1)

Abstract

The recent discovery of a giant oil field in the southeastern Beaufort-Mackenzie basin has brought this frontier area closer to oil production despite severe environmental conditions. The Amauligak field is a fault-bounded growth structure developed in the Kugmallit Trough, within deltaic deposits of the Beaufort Sea Shelf. Shelf construction occurred during the Late Cretaceous-Tertiary by repeated progradation of the Mackenzie River delta in response to rift-induced opening of the Canada basin and extension of the Kugmallit Trough. The Amauligak field contains oil and gas in multiple sandstone reservoirs of the Oligocene Kugmallit sequence. The upper sandstones are truncated by an unconformity and sealed by the overlying shales of the Miocene Mackenzie Bay sequence. Based on two-dimensional seismic coverage, the field was initially described as structurally simple. Interactive interpretation on Landmark and SIDIS workstations of a three-dimensional seismic program revealed the local structural complications, spatial configuration, and detailed structural elements of the field. Direct hydrocarbon indicators (DHIs), including amplitude anomaly, phase change, flat spot, and low-frequency zone, associated with a large gas cap were investigated using full amplitude-range and attribute-extraction methods. Interpretation of seismic data and correlation with well results suggest that a combination of structural, stratigraphic, and hydrodynamic factors are responsible for the appearance and distribution of Amauligak DHIs. On the amplitude displays, a flui contact is seismically mappable over the field, clearly separating the gas cap from the wet reservoir.