ABSTRACT

In the panhandle of Oklahoma, Upper Morrow 'A' sandstones produce hydrocarbons from point bar reservoirs. These sandstones were deposited within meander belt trends as isolated sand bodies. Recognizable sand body subfacies are lower point bar, upper point bar and swale fill based upon vertical sequence, stratigraphic position and map pattern. The location of abandoned channel fill facies relative to the sand body distinguished neck from chute cutoffs. Identification of any one of these is significant for finding the main point bar sandstone.

Sandstone geometry displays an ovoid to arcuate pattern, unlike the linear or shoestring pattern as predicted by classic models. Upward fining SP sequences were not common. Blocky SP character was noted in most wells. The predominance of the blocky sequence is attributed to the preservation of transitional to intermediate depositional facies. Transitional facies display abrupt upward transitions from sand to mud and result from deposition along sharply curving meander bends and from bend migration history.

Subsurface logs provided data to measure fluvial parameters and to estimate the hydrology of the ancient Upper Morrow river. These estimates suggest that the river was a meandering mixed load stream and compares favorably in wavelength, meanerbelt width, radius of curvature and mean discharge to the Upper Mississippi and Lower Missouri Rivers.