ARNOTT, R.W.C., University of Ottawa, Ottawa, Ontario

ABSTRACT: The Influence of Changing Relative Sea Level and Sediment Supply on Reservoir Characteristics of the Falher "D" Pool, Deep Basin, Alberta.

In the Deep Basin area of northwestern Alberta and northeastern British Columbia the Falher Member of the Spirit River Formation (Early Albian) is a major gas producer. A detailed pool study of the Falher "D" Pool (reserves estimated at 160 Bcf) was conducted in order to better

understand the sedimentological controls that were influencing the observed production characteristics, and the currently mapped pool outline.

The identification of a sequence boundary within the principal reservoir interval was paramount in understanding the distribution of reservoir lithologies within the "D" Pool, and the reason for the abrupt northern pool boundary. Following the relative sea level fall that created the sequence boundary, the shoreline stabilized basinward (northward) and during an ensuing stillstand deposited a lowstand shoreline succession. Subsequently, a rise of relative sea level returned the Falher shoreline into the "D" Pool area. Again, shoreline progradation associated with stillstand deposited a nearshore, shoaling-upward succession. These strata, however, are sandstone-dominated and because of pervasive quartz cementation are non-reservoir. Conversely, strata deposited before the relative sea evel fall (below. the sequence boundary) consist of non-reservoir sandstone, but also reservoir-quality conglomeratic strata. This suggests, therefore, that although relative sea level changes were important in determining various sedimentological and spatial characteristics of strata within the "D" Pool, the influence of temporal changes in sediment supply to the ancient Falher shoreline had profound implication, particularly economic.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.