DBRM

The Gilbertown Field

Choctaw County, Alabama

The Gilbertown Field is the oldest commercial producing field in Alabama having been in production since the 1940’s. In 2005 and 2006, a full geological study of the seven producing Eutaw Sands and the fractured Selma Chalk intervals by an independent geological consultant was conducted. This study built on work and a 2000 paper by AAPG distinguished lecturer Jack Pashin funded by the DOE (Department of Energy). These studies together suggest large reserves of oil remain in the East Gilbertown field.
In December 2006, Daybreak agreed to participate in the workover and repair of 19 existing well bores, and the drilling of one test well in potential Eutaw sand and Selma Chalk zones at depths of 3,000 to 3,500 feet. The principal producing zone is the multiple sand horizons in the Lower Cretaceous Eutaw sands. Between December 2006 and April 2007, Daybreak increased its working interest to 12.5%. On June 1, 2007, Daybreak became operator of the Gilbertown Field. Daily oil production has risen from 25 Bbl (Barrels) to in excess 85 Bbl in October 2007.

 

Geological Summary

The first discovery of commercial oil in the Gilbertown area was made in February 1944, in the Hunt #1 A.R. Jackson well in Choctaw County. The well found oil in the fractured upper Selma Chalk and was completed open hole, after drilling to a depth of 5,524 feet. Some 5 months later Hunt #2 found oil in the Eutaw sands in the Langsdale Field and in August 1945 the first well in the East Gilbertown field was drilled at Cater #1 Sam Alman in Section 5, Township 10, Range 3 West. Approximately 14 MM barrels of oil were produced from the Eutaw sands in the Gilbertown area and about 2.1 million barrels were produced from the fractured Chalk. The oil gravity from both formations ranges from 15°API to 19°API.
The Upper Cretaceous reservoirs of the East Gilbertown Field are set up on the south side of the Gilbertown Fault trend which is part of the Pickens-Gilbertown –Pollard Extensional Graben system. This was possibly formed as part of the Mississippi Interior Salt Basin as the faults mark the northeast margin of this basin. The faulting is the major trapping mechanism in both the Eutaw Sands and the Selma Chalk. The Chalk wells are found on the down thrown side of the faults where natural fracturing of the rock is most intense. The deeper Eutaw Sands are found trapped against the fault on the up thrown side. The geometry of the faults is such that a single vertical well can find production in both zones.