The Talco oil field in northwest Titus and northeast Franklin counties, Texas, is located in the north-central part of the East Texas basin on a fault structure which comprises a part of the Mexia-Powell-Talco fault zone. Most of the oil produced from earlier discoveries along this fault zone, such as Mexia, Powell, and Wortham, came from the Woodbine sand. Although the Talco fault was mapped by surface geology as early as 1924, the W. B. Hinton et al. C. M. Carr No. 1, field discovery well, was not completed until March 13, 1936. This well established the first Paluxy production along this fault zone and proved the Paluxy formation to be a major oil-producing section in northeast Texas.

A detailed description of the stratigraphy of the area is presented, which includes beds from upper Jurassic to lower Eocene in age. Data concerning the formations below the Paluxy were derived from several deep tests which were abandoned as dry holes.

The structure at Talco is a crescent-shaped graben, approximately 35 miles in length, bounded by two nearly parallel faults. The faults have a maximum surface displacement of about 360 feet which increases with depth to more than 1,400 feet on the base of the upper Glen Rose. Early and long continued movement is indicated by a thickening of the late Comanche and early Gulf formations in the graben. The oil accumulation, which is trapped in upthrown Paluxy against the south or basinward side of the graben, underlies about 9,000 surface acres. It is 13 1/4 miles long and averages one mile in width. Closure on the base of the Goodland limestone, which occurs at the top of the oil column, is approximately 450 feet.

The reservoir sands are generally variable in their development throughout most of the field. About one-fourth of the Paluxy section in the oil column is considered effective oil sand with an average thickness of 44 feet and an average porosity of 25 per cent. The average permeability is 2,460 millidarcys, ranging from a minimum of 100 to a maximum of about 10,550 millidarcys. Talco crude is brownish black to black in color, and the gravity varies from about 16° in the basal part of the oil column to slightly more than 25° at higher levels. An imperfect water drive and the greatly undersaturated condition of the crude oil resulted in a rapid decline of bottom-hole pressures, and it became necessary during the early life of the field to pump all wells.

On June 1, 1947, there were 728 producing wells in the field with a total allowable of 24,579 barrels per day. Cumulative oil production to July 1, 1947, was 97,369,193 barrels.