Abstract

The Albert Formation (Horton Group) of the Moncton Basin, New Brunswick, is host to the only onshore petroleum system in the Maritime Provinces from which oil and natural gas are commercially produced. Production from the McCully gas field is from tight reservoir sandstone in the upper part of the Albert Formation. An outcrop analogue is herein identified on the basis of a comparison of subsurface and surface gamma ray logs. The analogue is exposed in four roadcuts 15 km to the west of the field, between Sussex and Norton. The succession in the roadcuts is about 60 m thick and can be divided into three, roughly 20 m thick units: a lower interbedded grey mudstone and sandstone interval, a medial organic rich grey mudstone interval, and an upper interbedded grey sandstone and mudstone interval. The lower interval is interpreted as having been deposited in a lacustrine offshore transition and lower shoreface setting. The overlying medial interval is interpreted as offshore, with the upper interval assigned to a lacustrine shoreface and shoreline (with some fluvial, possibly deltaic influence). The lower and upper interbedded sandstone intervals are viewed as progradational sediment packages deposited during times of stable lake level whereas the intervening mudstone-dominated medial interval represents a period of renewed lake deepening. On a larger scale, the entire succession is considered part of the final progradation of an axial fluvio-deltaic system into the Albert lake.

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