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Abstract: Comparison of 2-D and 3-D Seismic Data in the Imaging of Nevada's Grant Canyon and Bacon Flat Fields

David W. Zwart, Eric H. Johnson

In 1993, a state-of-the-art 3-D seismic survey was acquired by Apache Corporation and its partners over the Grant Canyon and Bacon Flat fields, Railroad Valley, Nevada. Prior to that time, only 2-D seismic data had been recorded over these structurally complex fields. The 2-D grid consisted of numerous different vintages of data shot in a wide range of orientations by a variety of operators. Some of these lines appeared to correctly image the structural picture derived from the subsurface data in portions of the area. However, most of the lines tied poorly to the well control on the crest and east flank of Grant Canyon field.

Overall, the migrated 3-D data set provided a much more accurate tie to the existing well control. Elimination of out-of-the-plane reflections and a reduction of multiple events are the primary reasons for the image improvement. Comparisons of 2-D lines with corresponding vertical slices through the 3-D volume will be shown to demonstrate the relationship of seismic events to the borehole data. Seismic lines through the four new wells that were drilled on the basis of the 3-D survey will also be reviewed.

The 3-D data volume is not able to properly resolve complex structural geology until it has been 3-D migrated. Migration of a 2-D stack line from the 3-D survey for preliminary interpretation purposes may yield a surprisingly different section from the same line after true 3-D migration, and thus could lead to erroneous conclusions.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada