About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 33 (1949)

Issue: 12. (December)

First Page: 2069

Last Page: 2069

Title: Cairo Field, Union County, Arkansas: ABSTRACT

Author(s): L. A. Goebels

Article Type: Meeting abstract

Abstract:

The Cairo field was discovered in July, 1948. Production is from the Reynolds oolite member of the Smackover limestone of Jurassic age. The field is almost completely developed with 15 producing oil wells and 3 dry holes. The reservoir does not have a gas cap. The structure of the field is essentially an anticline trending northeast-southwest and oddly enough at right angles to the Schuler structure. There are no indications of faulting. The Cairo field is unique in several features. 1. Although regionally updip from the Schuler field, its apex is almost 100 feet lower than that of Schuler. Wells on the west flank of Cairo produce oil 180 feet below the oil-water contact at Schuler. 2. It is the first field in South Arkansas to show definite south limits of the Buckner re shale and anhydrite section. 3. Each producing well has a different oil-water contact. Evidence can be shown to support the theory that the various oil-water contacts are part of a tilted surface rather than the result of different zones of porosity. 4. Wells on the east side of the field where the oil-water contact is high recover oil-saturated porous limestone in cores but on drill-stem tests recover salt water. The subsea depth of 7,540 feet appears to have been the original oil-water contact. Factors which might have affected the original oil-water contact are discussed.

High recoveries with the diamond core-barrel and a complete analysis of all cores made possible a detailed study of the lithologic character of the oolitic limestone. Oolite zones vary laterally and vertically and it is difficult to correlate them from one well to another. The highly porous, loosely cemented oolite zones are best developed in the central and south portions of the field. The transition from clastic to chemical deposition is evident in the top of the Smackover on the north flank of the structure. There is no evidence to suggest that the structure is of reef origin.

End_of_Article - Last_Page 2069------------

Copyright 1997 American Association of Petroleum Geologists