Seismic Expression of Upper Morrow Channel Sands, Western Anadarko Basin, Oklahoma and Texas

Jens R. Halverson

In the western Anadarko basin (western Oklahoma and Texas panhandle), the Lower Pennsylvanian upper Morrow channel sands are both a prolific and elusive exploration target. Initial production from some of these sands can reach well over 1,000 BOPD, and yet an offset well only 1,000 ft away from a good producer can miss the channel sand entirely. This paper explores the use of high-resolution seismic data and color seismic inversion techniques in detecting the sands before the drill bit.

One-dimensional merged log modeling, two-dimensional log interpolation modeling, color seismic inversion processing, and seismic facies mapping techniques have been applied to two upper Morrow channel-sand fields in the Texas panhandle: the Lear and Darden fields. The channel sands reach an isopach thickness of 40-50 ft at a depth below surface of 8,000-10,000 ft, putting the channel sands within the "thin bed regime." This location is also below the "tuning point" where there is a correlation between the amplitude of the reflection and the thickness of the channel sand. The sands reach an interval velocity of 13,500 ft/sec and are encased within hundreds of feet of shale with an interval velocity of 10,500 ft/sec, providing a good acoustic impedance contrast and making the sands dete table on good signal-to-noise ratio seismic data. Comparison of geologic isopach and geophysical seismic facies maps shows a good correlation in the delineation of the upper Morrow channel sands.

The use of these seismic-stratigraphy methods should substantially increase exploration and development success when high-resolution seismic data and advanced interpretation techniques are employed.

AAPG Search and Discovery Article #91039©1987 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma, September 27-29, 1987.