Abstract

La Pan field, in central Clay County, is productive from the Chappel Limestone (late Mississippian) and several zones of Atoka conglomerates (early Pennsylvanian).

Mississippian production was established in April 1955, and six wells produced 902,500 BO and 4220 MMCFG through September 1962 when the field’s primary operations were abandoned. The reservoir, created by structural entrapment in a biohermal reef, was converted to gas storage in April 1978. Restoration of reservoir pressure stimulated additional oil recovery, and from December 1978, when the first gas was extracted, through June 1980, 43,905 BO have been produced by secondary recovery.

Production from Atoka conglomerates was first reported in February 1971, and twelve wells have produced 56,491 BO and 37.6 MMCFG through June 1980. Conglomerate production is associated with a combination of structural and stratigraphic entrapment, emanating from deposits flanking the underlying Mississippian build-ups. Conglomerate development in the area follows channels, but the thicknesses of individual zones and the porosity development within those zones vary considerably.

The conditions that exist at La Pan field are repeated in many other locations within Clay County, as well as in other parts of the northern Fort Worth basin. Similar conglomerate production might be established in some of these areas which have not been fully tested. La Pan’s history as a gas storage reservoir demonstrates an efficient, dual-purpose method of secondary recovery which can also serve as a model for other fields of a similar nature.