Abstract: A Petrophysical Model for Delta-Front Deposition
in the Pennsylvanian Cross Cut Sandstone, Runnels County, Texas
HENDERSON, S. K., Halliburton Energy Services,
Odessa, Texas andG. B. ASQUITH, Department
of Geosciences and The Center for Applied Petrophysical Studies, Texas
Tech University, Lubbock, Texas
Deltaic facies often exhibit different reservoir properties and, as
a result, successful exploration strategies for productive sandstones depend
upon the delineation of individual facies. Facies identification is relatively
straightforward, provided adequate core and well control exist; however,
in fields where cores are rare, identification of facies must rely heavily
upon observed log signatures and reservoir geometry.
Sediment characteristics, log responses, and sand body geometry are
employed to depict the depositional setting of the Pennsylvanian (Missourian)
Cross Cut sandstone in the TWP and Busher fields of Runnels County, Texas.
A majority of the Cross Cut in these two fields is interpreted as delta-front
sand that was deposited at the distal terminus of a prograding delta lobe.
Longshore reworking has resulted in a sand body that is asymmetrical about
the axis of the distributary mouth bar/channel trend.
The distribution of the delta-front Cross Cut sandstone with respect
to its fluvial feeder system is explained through a depositional model
that invokes progradational deposition followed by marine transgression.
Log-derived relative sea level curves, together with petrophysical comparisons
of shales underlying and overlying the Cross Cut sandstone, support a major
AAPG Search and Discovery Article #90936©1998 AAPG Southwest Section Meeting, Wichita Falls, Texas