The Walnut Bend pool is the first major deep discovery in the Marietta-Sherman syncline, a northwest-southeast trending feature which extends from southwestern Carter County, Oklahoma, to southeastern Grayson County, Texas, parallel to the Criner Hills axis and the Muenster Arch. In this pool 1,000 feet of Comanche rocks overlie the 4,200 feet of Upper and Middle Pennsylvanian (Canyon and Strawn) sediments, and beds of lower Simpson (Oil Creek) age underlie the Pennsylvanian rocks. Pre-Pennsylvanian rocks show the Walnut Bend structure as an elongate anticline. This structure was formed on an arch folded in early Pennsylvanian (pre-Bostwick) time and the Marietta-Sherman syncline was formed in late Deese time by the downwarping of the middle part of this arch. Over one an one-half million barrels of oil have been produced from 6 sandstone zones between the depths of 4,100 and 5,100 feet, and from 2 dolomite beds in the Simpson group. Occurrence of oil in the sandstone zones at 4,900 and 5,100 feet is controlled by anticlinal structure over the closely folded Ordovician beds, Electrical log cross sections are presented to indicate that oil in the 4,100-, 4,600- and 4,700-foot zones occurs in a stratigraphic trap formed by gradation of standstone into shale.

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