SOLIMAN, OSAMA M., and JOHN D. HARPER, Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, Canada

ABSTRACT: Transgressive Depositional History of the Ben Nevis Formation, Hibernia Oil Field, Grand Banks, Newfoundland, Canada

Integrated core analysis and well log correlation have provided insights into the depositional history of the Ben Nevis Formation. The formation starts at base with lagoonal sediments which erosively overlie soil deposits. The lagoonal sediments change westwards into flood plain mudstones. Laterally extensive clean sandstones, 5 to 11 meters thick, erosively overlie the lagoonal and flood plain sediments. The sandstones were deposited in back barrier-lagoonal environments, dominated by waves and tides. The sandstones and mudstones are erosively overlain by transgressive lag deposits, composed of well rounded cobble to boulder basement clasts in sandy matrix. The lag represents barrier shoreline gravels that spread westwards above the sandstones, when the advancing sea overrode the bar ier. In the west, this lag is overlain by progradational shoreface and lagoonal sediments. In the east, the lag is overlain directly by offshore mudstones with mouth bar sandstones. The shoreface and occasionally the mouth bar sandstones are overlain by erosive inundation lags and then by offshore mudstones. Rooted-marsh deposits commonly develop above the mouth bar sands.

The clean sandstones have sheet geometry and represent the most laterally continuous reservoir rock. Shoreface reservoir sandstones are predicted to trend in a NW-SE direction. Lobate-shaped mouth bar sandstones are best developed in the SE part of the field.

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