Publication Date:
2004-03-01
Description:
The Meren E-01 (Agbada Formation, middle Miocene) reservoir offshore Nigeria consists of a lower progradational shoreface succession terminated by a minor sequence boundary, overlain by a progradational and retrogradational shoreface succession. Deposition occurred in a wave-dominated delta front, as indicated by the presence in core of hummocky cross-beds, slumped units, and turbidites. Eight flooding surfaces were correlated, and isopach maps, sandstone-quality trend maps, and mudstone-quality trend maps were constructed for each parasequence. This work revealed a complex reservoir architecture characterized by shoreface clinoforms and a history of progradation and retrogradation cycles. Three different three-dimensional geological characterizations of the E-01 reservoir were built: a geostatistical model that used only well data; a more geologically complex facies-based model that used the sandstone-quality trend maps in addition to well data; and the most geologically complex sequence-stratigraphic model that used mudstone-quality trend maps in addition to the above data. The three models were analyzed in terms of sandstone continuity and connectivity to hypothetical injector and producer wells. Only the sequence-stratigraphic model predicted significant vertical compartmentalization through tortuosity generated by flooding-surface mudstones. Waterflood fluid-flow simulation of a downdip sector of the geologic models predicts similar recovery for the three models, but a significantly different distribution of unswept oil. Only the sequence-stratigraphic model identified parasequences with abundant unswept oil that are large enough to be economic infill prospects. History-matched, full-field fluid-flow simulations verify both the reservoir compartments predicted by the sequence-stratigraphic model and infill targets. Dave Larue has worked for ChevronTexaco Corporation for the past six years studying sequence stratigraphy and geologic modeling. Formerly, he worked at Exxon Production Research. Prior to joining the oil industry, he was a professor at the University of Puerto Rico and an original member of “los Profesores,” a rock-and-roll band that toured the western part of the island for several years. He received his Ph.D. from Northwestern University and was the last Ph.D. student of Larry Sloss, the father of sequence stratigraphy. He is an AAPG Visiting Petroleum Geologist and member of the AAPG Distinguished Lecturer Selection Committee.Henry Legarre received his M.S. degree from San Diego State University. He started working at ChevronTexaco in 1991, after spending some time at Scripps Institution of Oceanography, and Woods Hole Oceanographic Institute. He has worked for ChevronTexaco as an Earth scientist in California (Bakersfield, La Habra, and San Ramon), Luanda, Angola, and is currently in Lagos, Nigeria. His areas of expertise are production geology, geochemistry, carbonate and clastic stratigraphy, reservoir characterization, and geologic modeling. He has also been the chairman of the AAPG Student Chapter Committee and serves on the AAPG Grants-in-Aid Committee.
Print ISSN:
0149-1423
Electronic ISSN:
1943-2674
Topics:
Geosciences
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