Abstract

The BP Keathley Canyon 102 #1 well (Tiber) encountered 1650 ft (500 m) of Upper Cretaceous deepwater sandstones and mudstones 345 miles (550 km) from coeval deltaic systems. The KC 102 #1 well logs, core photos, reservoir quality studies, and biostratigraphic data BP recently released to BOEM provide new insights into poorly understood Upper Cretaceous deepwater systems in the northern Gulf of Mexico, as well as the potential of this emerging play—recently tested at the BP Galapagos Deep Prospect in Mississippi Canyon Block 518.

While fluvial-deltaic sediments of the Upper Cretaceous Tuscaloosa Formation are well-known reservoirs, data from the deepwater deposits associated with these deltas are very limited. Earlier interpretations of a Cenomanian-Turonian age were made before biostratigraphic data had been released (Woolf, 2012; Snedden et al., 2016). Siliciclastic environments of the underlying Albian section of the Paluxy-Washita supersequence are even less well understood.

BP cut 235 ft (72 m) of core in the Eagle Ford–Tuscaloosa and Paluxy-Washita supersequences. The facies observed in this core differ in significant ways from sediments of the overlying Paleogene Wilcox Group, including: (1) the sandstones are coarser grained (upper fine to lower medium sand-size); (2) there is a significant component of coarse-grained sand and granules; (3) muddy sandstones (slurry deposits) are rare; and (4) sandstones are quartz-rich. The facies observed in core along with log motifs of the uncored interval suggest deposition in basin-floor submarine fans—in both distributary channel-fill and fan lobe sub-environments.

Although these Cretaceous sandstones are thick and coarse-grained, they are also quartz cemented and have locally pervasive carbonate cements. As a result, reservoir quality is very poor with permeabilities <1 mD and porosities in the 2–10% range. If encountered under conditions of lower temperatures or with chlorite overgrowths, this would have reduced quartz cementation and would have lead to better reservoir quality.