Hybrid plays of Upper Triassic Chang7 lacustrine source rock interval of Yanchang Formation, Ordos Basin, China

The lacustrine Chang7 member of Upper Triassic Yanchang Formation in the Ordos Basin in North China is a source rock interval characterized by organic-rich shale with thin interbeds of stratigraphically associated sandstone and siltstone. The concept of “Hybrid Plays” is put forth after evaluating the facies, geochemistry, porosity, permeability, mineralogy and producibility of different lithofacies in this Chang7 member. The genetically related hydrocarbon bearing hybrid unconventional shale, tight sand and conventional reservoirs within the source rock interval are identified. The interbedded organic-lean reservoirs are efficiently charged with hydrocarbons through short migration from the adjacent organic-rich Chang7 shale that is also a self-sourced shale reservoir. The hydrocarbon accumulation of these hybrid plays has been confirmed by petroleum system modeling and recent exploration and production. “Hybrid Plays” present a unique closed petroleum system hosting continuous hydrocarbons stored in self-sourcing thick shale reservoirs and adjacent thin and relatively coarse-grained siliciclastic interbeds, that together form hybrid unconventional plays in addition to conventional plays throughout the whole source rock interval. “Hybrid Plays” provide the most realistic exploration and production model for targeting the multiple genetically associated stacked plays as one resource play in order to avoid relying solely on clay-rich shale or thin relatively coarse-grained interbed play in source rock intervals of this lacustrine basin.