Seismic Expression of Upper Morrow Channel Sandstone, Western Anadarko Basin

Jens R. Halverson

In the western Anadarko basin, the Lower Pennsylvanian Upper Morrow sandstones are a prolific but elusive exploration target. Initial production from some of these wells can reach over 1,000 BOPD, and yet an offset well just 1,000 ft away from a prolific producer may miss the sandstone entirely. High-resolution seismic data, along with advanced geophysical modeling, seismic inversion processing, and seismic facies mapping, are useful in detecting the sandstones before drilling begins.

Two upper Morrow fields in the Texas Panhandle have been studied: the Lear and Darden fields. The Morrow sandstones reach an isopach thickness of 40-50 ft at a depth below surface of 8,000-10,000 ft. The sandstones are within the "thin bed" regime. They are also below the "tuning point" where there is a linear relationship between the amplitude of the seismic reflection and the thickness of the sandstone. The sandstones have an interval velocity of about 1,000 m/sec faster than the encasing shales, and are detectable on good signal-to-noise ratio seismic data. The comparison of geologic isopach mapping and geophysical seismic facies mapping shows a good correlation in the delineation of the upper Morrow sandstones.

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 #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.