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Influence of Mass Transport Deposit on Stratigraphic Evolution, Channel Morphology, and Turbidite Reservoir Preservation and Architecture, Niger Delta, West Africa

By

Olusola Bakare1, Neil Hurley2, Timothy McHargue3, and Piret Plink-Bjorklund2

 

Search and Discovery Article #40249 (#2007)

Posted August 7, 2007

 

 

*Adapted from oral presentation at AAPG Annual Convention, Long Beach, California, April 1-4, 2007.

Please refer to companion article by Bakare et al., entitled “Effect of Growing Structures on Stratigraphic Evolution, Channel Architecture, and Submarine Fan Distribution, Niger Delta, West Africa.”

 

 

1Chevron International Exploration and Production, Lagos, Nigeria (olba@chevron.com )

2Colorado School of Mines, Golden, CO
3Chevron, San Ramon, CA

 

Abstract 

Mass transport deposits (MTDs) represent a major component of the Miocene-Pleistocene deep-water system, offshore West Africa. The goal of this study is to determine the influence of MTDs on stratigraphic evolution, turbidite channel morphology, and reservoir facies preservation and architecture in a slope portion of the Niger delta.  

The dataset used for this study is a conventional 3D seismic survey and a version of coherency volume. Although there are several wells in the area, there are no logs or cores in the study interval.  

The deposition of a thick MTD along the depositional axis of an older channel had a significant effect on the depositional setting of the basin, which included a change in channel morphology, a change in depositional axes, and erosional truncation of turbidite reservoir facies within confined channels.  

Depositional units in the study area have characteristic stacking patterns. MTDs occur at the base, overlain by distributary lobe complexes (DLCs), amalgamated channel complexes (ACCs), and they are capped by drape complexes (DCs). MTDs are very erosive, and they truncate part or all of the underlying reservoir facies. This study clearly shows that MTDs could act both as lateral and vertical seals for turbidite channel reservoirs.  

Channel morphology changed from highly sinuous in the oldest sequence to relatively straight in the youngest sequence, caused by the deposition of laterally extensive, thick MTDs over older channel deposits. There is also a variation in the architectural pattern of turbidite reservoir deposits between older and younger channels separated by MTD deposition.

 

Selected Figures 

Location maps of study area.

Regional tectonic setting.

Basin tectonic setting. Seismic lines A (structurally simple) and B (mud diapirs and growth faults).

Basin tectonic setting. Seismic lines C and D (mobile shale control of physiography).

Seismic facies.

Stratigraphy of seismic facies.

MTD types.

MTD I distribution.

Isochron maps illustrating MTD and paleotopography (in sequence—below MTD 1, inclusive of MTD 1, above MTD 1).

Example of MTD erosion.

Depositional model (in stages).

 

References 

Mitchum, R. M., M. W. Hoffman, C. D. Conners, A. M. Knowlton, and B. J. Radovich, 2000, Tectonic controls on regional sequence stratigraphy in the Niger Delta, offshore Nigeria (abs.): AAPG Annual Meeting Program, v. 9, p. A99.

Mitchum, R.M., and G.D. Wach, 2002, Offshore Niger Delta Pleistocene/Holocene leveed-channel fans – Models for offshore reservoirs (abs.): AAPG Bulletin, no. 13.

Short, K.C., and A.J. Stauble, 1967, Outline of geology of Niger Delta, AAPG Bulletin, v. 51, p. 761-779.

Corredor, Freddy, John H. Shaw, and Frank Bilotti, 2005, Structural styles in the deep-water fold and thrust belts of the Niger Delta: AAPG Bulletin, v. 89, p. 753-780.

 

 

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