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Reservoir Characterisation of Heterogeneous Deepwater Channel Complexes Within Deepwater Slope Systems — Examples from Angola Block 14 Slope Valley Systems

Nicholas Drinkwater1, Previous HitWilliamNext Hit Schweller1, Previous HitWilliamTop Crane2, and Oscar Yepes3
1ETC, Chevron, Houston, TX
2Chevron Southern Africa BSU, Houston, TX
3Chevron Southern Africa, Lenine, Angola

Detailed examination of core, wireline and image log data integrated with good quality, high resolution seismic data from over 30 cored wells in Angola Block 14 has demonstrated the heterogeneous nature of the channels preserved in these slope valley systems. From detailed facies analysis of the cores, over 10 principal lithofacies have been described. These lithofacies have been subsequently grouped into a limited number of principal reservoir facies associations, which range from high net, massive sand facies to finely laminated, thinly interbedded mudstones and sandstones of low overall sand content.

These main reservoir facies associations have been interpreted to form in channel-dominated, erosively-confined slope valley systems, where processes of bypass, sandy and muddy back-fill, channel margin collapse, progressive and sharp channel abandonment and post-depositional injection have all been identified in the core. Two fully cored examples of very contrasting channel complex styles have been chosen to illustrate some of the key reservoir heterogeneities present within these important reservoirs.

Successful discrimination of the main reservoir facies associations in the core enabled their identification in extensive high-resolution image log and lower resolution wireline log analysis for both non-cored sections of the wells under discussion, and other non-cored wells elsewhere in Block 14. In addition, through application of objective recognition criteria from the 1D data, a recognizable and predictive reservoir architectural hierarchy was established for these systems.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery