This paper comments on the importance of the nonmarine environment as a contributor of petroleum source materials, and, in connection with the problem of delayed generation or late primary migration, summarizes evidence indicating that much if not all of the oil in the Oligocene Oficina formation in central Anzoategui, Venezuela, has been trapped by structures developed in pre-Oficina time and that known post-Oficina structures are either barren of oil or are marginal producers.

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