The McFaddin-O’Conner, Greta, Fox, Refugio, White Point, and Saxet fields are approximately along the same strike, and field-to-field correlations are satisfactorily established.

In the Refugio and White Point fields most of the drilling was done before adequate coring methods and proper sample collection and examination facilities were established; hence, graphic log correlations, in themselves alone not very satisfactory, must be relied upon largely for structural pictures.

In the McFaddin-O’Conner, Greta, and Fox fields, drilling has not progressed to the point where complete structural pictures can be delineated, but intelligent coring, sample collection, and sample examination, have assisted in giving reasonably accurate subsurface data.

An accurate and fairly complete subsurface map may be drawn of the Saxet field.

It is believed that all of these fields are structural. The shapes of the producing areas, where they have been sufficiently outlined, have suggested that they are deep salt domes, although salt has not been found in any of them. Faulting of considerable magnitude is known to exist in connection with them.

Numerous producing sands appear in each field. Gas and oil production comes from both the Oligocene and Miocene beds, and, as a general rule, the gravity of the oil produced increases with depth.

The most reliable correlation markers are the Heterostegina and Discorbis zones, which have been considered Oligocene in age. Another marine zone, of doubtful value, and probably Miocene in age, is known to exist about 200 feet above the Discorbis zone.

Emphasis is placed upon the value of adequate coring in these fields. The difficulty of making reliable graphic log correlations of wells in the area which have not been properly cored is apparent to anyone attempting serious correlation work here.

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