--> Abstract: Near-Surface High-Resolution 3-D Seismic as a Tool for Guiding Earth Modeling and Field Development Planning—an Example from Offshore Niger Delta, Nigeria, by Adedayo Adeogba, Timothy R. McHargue, and Stephan A. Graham; #90039 (2005)

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Near-Surface High-Resolution 3-D Seismic as a Tool for Guiding Earth Modeling and Field Development Planning—an Example from Offshore Niger Delta, Nigeria

Adedayo Adeogba1, Timothy R. McHargue2, and Stephan A. Graham3
1 ChevronTexaco Overseas Petroleum, Houston, TX
2 ChevronTexaco Energy Technology Company, San Ramon, CA
3 Stanford University, Stanford, CA

The impact of understanding reservoir architecture and heterogeneity in field development and well planning and design has never been as great as in deep water field development where high well cost and capital investment heavily impact project economics. One of the pioneering tools driving better understanding of reservoir distribution and architecture is the use of near-surface high resolution 3D seismic datasets. The high resolution of these data sets provide images of architectural detail and facilitate the interpretation of facies distributions within systems that are analogous to productive reservoirs. A near surface 3D seismic dataset from the Niger Delta slope was studied as an analogue for reservoirs deposited in a slope setting where synsedimentary extensional faulting and mud diapirism form major structural/topographic controls on deposition from sediment gravity flows. These controls are exercised principally through changes in slope gradient, base-level changes and adjustment of equilibrium profiles, which have profound effects on fan development and inferred sand distribution. The mechanism for fan aggradation is likely through a hydraulic jump at abrupt reduction of slope gradient. Channel incision results from development and headward migration of knick points in response to adjustment of the equilibrium profile at an abrupt increase of slope gradient. Two fan types are described; Terminal Fans and Transient Fans. Terminal fans are sediment sinks with little or no evidence of significant sand bypass beyond the fan. Transient fans are short-lived sediment sinks with one or more incised channels through which sands are transported basin-ward of the fan. Significantly, hydrocarbon reservoirs in transient fan settings can be compartmentalized by incised channels which are very often shale filled. A comparison of transient fans in a mud diapir-dominated basin with ponded fans in more confined settings brings out distinctions that have important implications for both earth-modeling and field development.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005