Prospect Hammerhead (AC 943 #1 Exploration Well) Alaminos Canyon Protraction, U.S. Perdido Fold Belt, Gulf of Mexico

Abstract

Abstract

Hammerhead is likely the only faulted four-way closure straddling the US – Mexico border that has been drilled to date in the U.S. Gulf of Mexico. Hammerhead lies 1-2 miles southwest of the Great White producing field on the same structural trend in the Perdido Fold belt, and covers 3 OCS blocks: AC 899, 942 and 943, which, in 2004 were 100% Shell. Hammerhead was drilled 100% Shell on AC-943 in Qtr. 1, 2004 with the Global Santa Fe Jack Ryan rig in 7,955 feet of water to a proposed TD of 19,900 ft. TVDss. The planned top- and bottom-hole locations were 2814 and 1029 ft. north of the international border with Mexico, respectively. Part of the rationale to drill in 2004 was to understand how a discovery at Hammerhead would, impact Great White facility sizing decisions.

The primary objectives of this well were to drill the well safely and to penetrate and evaluate the amplitude supported Oligocene and Upper Wilcox intervals and the non-amplitude supported Middle and Lower Wilcox intervals. The depositional settings for these reservoir targets include lower to base of slope sheet/lobe and channel geometries within: 1) Oligocene mixed-load fan systems, 2) Late Paleocene to early Eocene Middle to Upper Wilcox mixed-load fans, sourced from the west to northwest, and 3) a Paleocene Lower Wilcox high N/G, north-sourced fan system.

The Hammerhead structure maps show a faulted three-way dip closed structure at all stratigraphic levels on the U.S. side of the border. The crest is located near the border with Mexico, and the structure is thought to close to the south in Mexico. Pemex refer to the structure on the Mexican side of the border as Magnanimo. Hammerhead is bounded by 3 NNE-striking reverse faults; one E-vergent bounding fault on the east and two en-echelon W-vergent faults on the west. The offset on the reverse faults is poorly imaged at the Cretaceous level; slip dies out at shallower levels (Upper Wilcox) and is accommodated by steep-limbed box folds. A NE-and N-trending set of conjugate crestal collapse normal faults are present in the Oligocene interval at Hammerhead which die out with depth to a neutral point in the upper Wilcox. The spill point of Hammerhead at all levels, in the U.S., is mapped to the northeast into the Great White structure.

The AC 943 #1 Hammerhead well TD'ed at 11,700 ft. MD after penetrating quality, high net-to-gross Oligocene Frio sands, without encountering any indications of hydrocarbon.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016