--> Stratigraphic Trapping in a Proximal Submarine Canyon: The Gabela Discovery, Angola, Block 14, by Joy M. Roth, George Burg, and Robert J. Minck; #90037 (2005)
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Stratigraphic Trapping in a Proximal Submarine Canyon: The Gabela Discovery, Angola, Block 14

Joy M. Roth1, George Burg2, and Robert J. Minck1
1 ChevronTexaco, Bellaire, TX
2 Burg GeoConsulting, Leander, TX

The Gabela-1 well marked the contractor group's 9th Previous HithydrocarbonNext Hit discovery in Angola's Block 14 since the start of the exploration concession in 1995. The discovery is significant for its size and for being trapped stratigraphically. The main accumulation is late Miocene (CN9), was deposited proximally within a submarine canyon, and appears to be the block's first occurrence of a pure stratigraphic trap.

The CN9 reservoir at Gabela-1 is within the AA canyon, a deeply entrenched paleo-Congo canyon running 50 km across Block 14 and beyond. The canyon's high energy environment caused multiple occurrences of erosion and deposition with episodic slumping and debris flows, yielding complex channel geometries. This is unlike the common "eyeball" geometry observed in the slope valley channels with lowstand turbidite sands overlain by a fining upward sequence. At Gabela-1, seismic reflectors are chaotic with no visible sustained periods of quiescence.

Post-drill volume visualization was used to better understand the trapping mechanism and reservoir geometry. Previous HitDirectNext Hit Previous HithydrocarbonNext Hit Previous HitindicatorsTop from the strong fluid effect suggest the presence of additional fluid contacts within the field. Geochemical analysis, used to compare oils, also suggests reservoir separation between the wells and between zones within the section.