Sedimentary model for the lower part of the third member of the Hetaoyuan Formation in the Anpeng district, Zhao’ao oil field, Henan

The facies indicators and fan delta sequences in the lower part of the third member of the Hetaoyuan Formation in the Anpeng district, Zhao’ao oil field, Henan are dealt with in the light of lithology, textural and compositional maturity, sedimentary structures and palaeontology. The sedimentary environments are dominated by the fan delta facies, which may be subdivided into the fan delta front subfacies and profan delta subfacies, and nearshore channel microfacies and offshore channel microfacies. The subfacies and microfacies outlined above are characterized by proximal provenances, shorter distance of transport, coarser grain sizes of sediments, lower textural and compositional maturity, intense hydrodynamics, well-developed massive beddings, parallel beddings and cross beddings in conglomerates and coarse-grained sandstones.