Proportional horizon slices of a 3D seismic amplitude volume from the Gulf of Mexico were generated using ARCO's proprietary 3D seismic interpretation software. We determine the relationship between seismic amplitude and lithology using synthetic seismographs and well logs. The slices of the Pleistocene-Pliocene sedimentary section clearly reveal fluvial meandering channel, deltaic distributary channel and mouth bar deposits. Channel deposits are difficult to identify on conventional vertical seismic profiles but are clear on horizon slices.

Meandering channel point bar deposits exhibit a series of crescenttic amplitude fields, whereas distributary channel deposits are shown as relatively low-sinuosity, linear amplitude fields on horizon slices. Deltaic distributary mouth bar deposits are expressed as a lobe-like amplitude field. The sandy nature of these deposits were confirmed by well data. Well-log cross sections clearly demonstrate that both the meandering and distributary channel deposits are characterized by blocky log motifs. Distributary mouth bar deposits show “funnel-like” motifs on logs, suggesting upward coarsening and thickening, and clinoform reflections on vertical seismic profiles along depositional dip. Proportional horizon slices, vertical seismic profiles, and well logs together provide an accurate determination of sandbody geometry. The ability for accurately imaging reservoir sandbodies using proportional horizon slicing can significantly reduce exploration and production risk.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah