Title: The effects of the petrology and diagenesis of mixed provenance sandstones on permeability heterogeneity and reservoir characterization
Abstract: The Comodoro Rivardavia Formation of the north flank of the San Jorge basin is a fluvial/alluvial fan sequence deposited during the late sag stage of rift basin development. Basin fill was derived from eroding volcanic arc to the west and northwest, contemporaneous volcanism, and the basement found to the north. Three petrofacies are recognized: a dominant petrofacies derived from plutonic, volcanic, and metasedimentary rocks (Q{sub 27}F{sub 21}L{sub 52}); a monolithologic volcanogenic sandstone composed entirely of volcanic detritus (Q{sub 6}F{sub 25}L{sub 69}), and a petrofacies recognized as a diagenetically (meteoric) altered derivative of a mixed provenance petrofacies (Q{sub 48}F{sub 9}L{sub 43}). Lateral and vertical variation of sandstone composition provides independent constraints on correlation of sandstones across a portion of the north flank. Factors which govern the diagenesis of the sandstones include burial history, compositional variations, meteoric influx, and presence and compositional variation of infiltrated material. Formation of late smectite as a result of uplift of the basin has increased heterogeneity of permeability. The meteorically altered sandstones have permeabilities that vary three orders of magnitude more than those sandstones that were not strongly leached. Infiltration of fines has reduced permeability, although the composition and extent of infiltration varies greatly. These postdepositional processesmore » have played an important role in determining reservoir heterogeneity.« less
Publication Year: 1991
Publication Date: 1991-03-01
Language: en
Type: article
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