VINSON, TOM E., Exxon Production Research Company, Houston, TX; PAUL A. LEONARD, Exxon Exploration Company, Houston, TX; and SCOTT R. MORGAN, Sequence Stratigraphic Consulting, Houston, TX

ABSTRACT: Optimizing Production with Existing Data: Evaluation of Seismic, Stratigraphic and Reservoir Data from Lena Field (MC 281)

Lena Field is a salt related structure located on the present-day Gulf of Mexico slope in 1000 feet of water. Since setting the platform in 1984, six sandstone reservoirs have produced approximately 40 MBO and 80 MMCFG. The depositional setting of these sands shoals upsection from intraslope fan to lowstand delta. Reservoir discontinuities at Lena are a product of both the structural and stratigraphic histories of the field. Major salt-related faults define reservoir boundaries at all horizons, but reservoir compartmentalization is also produced by small faults and the original depositional geometry of deep-water channels that are below seismic resolution.

Lena reservoirs were deposited as alternating sequences of sand- and mud-prone lithofacies in an intraslope to shelf-margin setting. Among slope basin deposits, log correlations for a given sequence--from top to base of sand interval--are usually reproducible, but individual sands within the sequence are not uniquely correlatable, despite close well proximity. Individual sands typically exhibit a fining-upward log character, from which a channelized, retrogradational stacking of lithofacies is inferred.

It is not possible to resolve small structural and stratigraphic discontinuities with conventional seismic interpretation techniques, therefore, seismic attribute maps were used for this purpose. Seismically derived hydrocarbon volumes closely matched values derived using conventional mapping techniques and determined from production data. The seismic attribute maps also indentified undrained reserves not located with conventional maps or production data. Seismic attribute mapping, using existing 3-D data, provides an economic method of predicting the volume and distribution of hydrocarbons in a reservoir.

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