--> Abstract: A New Look at Grant Canyon and Bacon Flat Fields with Integrated Seismic and Well Data, by E. H. Johnson; #90993 (1993).

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JOHNSON, ERIC H., Balcron Oil, Billings, MT

ABSTRACT: A New Look at Grant Canyon and Bacon Flat Fields with Integrated Seismic and Well Data

Grant Canyon and Bacon Flat fields are located along the east edge of Railroad Valley, Nevada. Bounded by normal faults to the northwest, northeast, and south, Grant Canyon is a triangular-shaped horst, 500 ac in size, with a producing area of 300 ac. One mile west and 1500 ft deeper, Bacon Flat field covers 100 ac of a 300-ac fault block that flanks the Grant Canyon horst.

Integrated seismic and well data show that Grant Canyon and Bacon Flat produce from detached Devonian dolomites that overlie younger Paleozoics. These reservoir rocks were emplaced before the fault blocks formed. The detachment surface had less westerly dip than the underlying strata, so that Pennsylvanian limestones underlie Bacon Flat and Mississippian shales underlie Grant Canyon. The normal faults bounding the fields have throws of 500 -1500 ft and predate Oligocene(?) volcanic deposition. Extensive erosion, coeval with faulting, helped isolate the Grant Canyon and Bacon Flat reservoirs prior to burial beneath valley-fill sediments.

The top of the Devonian reservoir can be obscure on seismic data. Well control has verified some erosional knolls, scours, drape, and onlap features not recognized before or dismissed as valley-fill artifacts. When 300 ac can yield 20 million bbl of oil (Grant Canyon), and a 20-ac knob might produce 1 million bbl of oil, attention to detail can be rewarding.

Meticulous seismic acquisition, processing, interpretation, and integration with well data and geologic models are essential. Surprising results were obtained by reprocessing poor-quality seismic data; an erosional knoll was imaged at the abandoned Bacon Flat field and spawned a prolific new well.

AAPG Search and Discovery Article #90993©1993 AAPG Rocky Mountain Section Meeting, Salt Lake City, Utah, September 12-15, 1993.