Abstract

The Ambra Strawn field (Fig. 1) is a typical meanderbelt deposit. Well logs together with sample descriptions support the concept of a point bar sequence of deposition. Structure on top of the Ambra sand, geometry, and sand thickness provide further evidence of a meandering stream deposit. The production of oil and water delineates “ridge and swale” features characteristic of the point bar.

The Ouachita foldbelt, which forms the eastern boundary of the Fort Worth basin, was the site of orogenic movement at various periods throughout Pennsylvanian time. It was the source of the Atoka fan delta facies which were later reworked and deposited as Strawn channel sands on the flood plain below. The environment of deposition is upper deltaic.

The final upwarping of the Ouachitas gave the Strawn beds a gentle dip to the north and the structure then affected the oil migration into the present position on the point bar, very near the channel.