Abstract

The Taglu gas field, discovered in 1971, is located near the outer fringe of the Mackenzie River Delta and within the Beaufort Basin. Four wells and available seismic lines currently define about 12 square miles of productive area within a structural closure along the upthrown side of a major detached growth fault.

Rapid permafrost thickness variations, related to the presence or absence of lakes and channels, give rise to anomalies which must be considered in geophysical mapping of the structure.

Multiple sand reservoirs below 7700 ft produce gas from a 1700 ft thick delta-front sequence of probable Eocene age. Gas legs of up to 1700 ft fill the closure almost to the spill point.

About 75% of the Taglu gas reservoirs consist of beach and stream mouth bar sands. Distributary channel sands make up approximately 15% and shoreface sands about 10%. Net sand thicknesses in the wells vary from about 450 ft to 600 ft.

Abundant organic-rich, delta-front shales interbedded with the reservoir sands are the most likely source of the Taglu hydrocarbons. As a result, a relatively small drainage area is required as a source for hydrocarbons to the field. An immature, woody hydrocarbon source or biodegradation is indicated by the relatively high aromatic content of the 47° API gravity condensate. Wet gas reserves are estimated to be in excess of 3 Tcf.