Pestman, Pieter1, Masashi Hirano1,
J. Michael Moldowan2 (1) Teikoku Oil Co. Ltd,
The Espino Graben
is one of the future exploration plays in
Geochemical data (diamondoids) obtained from oils in Tertiary sediments indicate that, although most of the oil has been generated by Tertiary and Cretaceous (i.e. post-rift) source rocks, some oil comes from a highly mature source. Upper Jurassic and several Paleozoic intervals were identified as potential sources for this oil.
Further geochemical analyses and basin modeling were carried out
in order to obtain more information about the possible petroleum system(s) in
the Espino Graben.
Geochemical analyses included an evaluation of diamondoid
and biomarker isotopes in oil samples from the Espino
Graben and some Jurassic/Paleozoic oil and
source-rock samples from other areas. Basin modeling included a tectonostratigraphic and paleogeographic
It was concluded that Jurassic, and possibly also Paleozoic, source rocks may have been generating hydrocarbons in the Espino Graben and that these may have been trapped in structures within the graben. However, uncertainty remains regarding (1) the presence of effective seals in the syn-rift tectonosequence, and (2) reservoir quality.