MMS Releases Summary of Lower Tertiary Play in Gulf


The Minerals Management Service (MMS) released a summary of discoveries industry has made in the Lower Tertiary Trend in the offshore ultra-deep waters of the Gulf of Mexico (GOM) (on figure 1). The map provides the locations of the 12 announced discoveries.

Lower Tertiary formations were deposited from about 65 million to about 35 to 23 million years ago. Discoveries in the GOM Lower Tertiary have been from variable depths, wells drilled as shallow as 15,000 feet in some areas and as deep as 30,000 feet in others.

"This is an exciting new trend in the Gulf of Mexico, and the recent announcement by Chevron and its partners of the results of the Jack 2 well provides additional proof of its great potential," noted MMS Director Johnnie Burton. "This trend began to materialize in 2001 and 2002 with several discoveries in the Alaminos Canyon and Walker Ridge areas and now has extended to the Keathley Canyon area. The area could be as wide as 300 miles and involve as many as 3,000 blocks that MMS administers."

The importance of the deepwater extension of the Lower Tertiary Trend, which has long been recognized as a major petroleum resource throughout the Texas and southwestern Louisiana area, is the significant increase in oil and gas reserves it will provide for decades to come. Until these recent announcements, the reserve contribution of the Lower Tertiary in the Gulf was negligible. Ninety-nine percent of the GOM proved reserves were found in sediments less than 23 million years of Miocene age (Upper Tertiary) and younger, while one percent of the proved reserves are in older than 65 million years (Jurassic and Cretaceous age) sediment, which are primarily in nearshore areas offshore Louisiana and Alabama.

MMS officials also noted that the widespread industry interest in the Jack well test and the discovery by BP on its Kaskida prospect in 5,860 feet of water preceded heavy bidding activity at MMS's Western Gulf Sale 200 in August. At that sale, 82 tracts received bids in the Keathley Canyon area. In addition, the highest bid at the sale was offered by BP at $21 million for Block 58 in Keathley Canyon, Petrobras bid $12.8 million for Block 59 there, and Shell bid $6.0 million for Block 56. These bids further illustrate industry's high interest in this area and, with its development, the subsequent growth in the nation's offshore deepwater resources.

Publicly Announced Lower Tertiary Trend Discoveries (Figure 1)

Prospect Block Operator Discovery Date
Trident AC 903 Chevron 2001
Great White AC 857 Shell 2002
Cascade WR 206 BHP 2002
Chinook WR 469 BHP 2003
St. Malo WR 678 Chevron 2003
Tobago AC 859 Chevron 2004
Silvertip AC 815 Chevron 2004
Tiger AC 818 Chevron 2004
Jack WR 759 Chevron 2004
Stones WR 508 BP 2005
Gotcha AC 856 Total 2006
Kaskida KC 292 BP 2006