The Healdton field, in the northeast half of T. 4 S., R. 3 W., Carter County, Oklahoma, produces oil principally from the Hoxbar Group of Pennsylvanian age and the Arbuckle Group of Early Ordovician age. Oil production was established first in 1913 from four Healdton sandstones (Hoxbar).

Several of the earlier development wells were drilled into the pre-Pennsylvanian rocks and penetrated a part of the Arbuckle section, where some oil production was found. Commercial potential from the Arbuckle, however, was not recognized until 1960.

The Arbuckle now produces primarily from three dolomite zones that are developed in the upper 1,600 ft of a 5,000-ft, predominantly carbonate section. The Wade and Bray zones, the upper two zones, are characteristically thin-bedded saccharoidal dolomite with associated shale and anhydrite. Because of poor permeability, these zones are not considered to be significant contributors to the recoverable reserves.

The Brown zone is the lowermost productive unit of the 1,600-ft interval and is the field's primary Arbuckle objective. It is a crystalline dolomite approximately 600 ft thick with intercrystalline porosity and excellent permeability resulting from a highly developed fracture system. Structural closure is more than 1,500 ft with as much as 700 ft of oil column.

Entrapment of hydrocarbons was effected by a northwest-southeast anticlinal trend that is a result of the Wichita Mountains-Criner Hills orogenic movement which originated in Early Pennsylvanian time and was activated again during Late Pennsylvanian time. Although gently folded Hoxbar strata lie upon a deeply eroded pre-Pennsylvanian surface, the underlying Arbuckle is more tightly folded and is complicated by faulting.

The Hoxbar sandstone beds, from an average depth of 1,000 ft, have yielded more than 230 million bbl of oil. The Arbuckle produces from an average depth of 4,000 ft and had a cumulative production of 1,080,883 bbl of oil as of January 1966.