Tracy Gas Field, New Shallow Production
STERLING, ROBERT, and RODNEY NAHAMA, Nahama & Weagant Energy Company, Bakersfield, CA
The Tracy Gas field was the first commercial gas production in California. Amerada Hess found production in the Cretaceous Tracy Formation in 1934. Five production wells ultimately produced 13 BCF by 1959. In 1989, Nahama & Weagant Energy Company (NWEC) purchased seismic data acquired by Shell Oil in 1980. The data was reprocessed for amplitude vs. offset (AVO) analysis. The data showed a bright spot at 1.0 section that exhibit an AVO response indicative of the presence of gas. Log data suggested the
possibility of gas in the based Miocene Zilch Sands in the Amerada F.D.L. number 4 well drilled in Sec. 15, T2S, R5E drilled in 1934. Husky Oil found gas production in the Zilch with the Rossi Number 1 well drilled in 1980. The most obvious problem with following up Husky's well was the J. M. Young Cordoza Number 1, a dry hole, that was misplotted on all of the commercially available base maps. The Amerada FDL Number 4 well also had to be interpreted to show gas in the Zilch which was a difficult interpretation to make on a log run in 1934. Nahama & Weagant Energy Company drilled the Tracy 1-15 well in January 1990 directionally to test the Zilch sands in Sec. 15 almost exactly where the dry hole had been misplotted, resulting in a discovery of 48 net ft of pay in the Zilch. The T acy 2-15 was drilled in March 1990 to twin the Amerada F.D.L. Number 4 well resulting in 104 ft net pay in the Zilch. The two wells are presently producing 3000 MCFD combined. The Miocene gas is present in basal Zilch sands that were deposited unconformably on the Cretaceous Blewett Formation. The gas is located on the west flank of the Tracy anticline which is formed by a 90 degree bend in the Vernalis fault, a thrust fault with over 1600 ft of vertical movement. The Vernalis fault had movement as recently as the Pliocene, based on seismic data. Due to the relative youth of the fault, deeper potential in the Winters and Lathrop formations is believed not to exist on the Tracy anticline.
AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)