It has been shown through organic geochemical study that there exist
four oil--generating strata:lower Cambrian black grey shales, Permian dark
grey organic limestones and black grey shales, middle Triassic Leikoupo
formation dolomites, and Upper Triassic Xu jiahe formation grey black
mudstones and coal beds in the overthrust nappe and its leading edge.Re--
servoirs in the area are characterized by low porosity, low permeability,
intensive structural damage and poor oil一preserving conditions, but they are still favourable for finding structural or lithostructural oil and gas pools in
weakly pressed, completely preserved structures in the frontal zone, such
as the downblock of the south-eastern flank of Tian jinshan anticline，Feng-
shunchang protruding anticline.
