Abstract

The main controls on petroleum accumulations in sedimentary basins include source-rock distribution, thermal maturity, migration pathways, and structural and stratigraphic traps. Whereas shale plays and conventional reservoirs are end members governed by contrasted geological processes, unconventional hybrid systems represent a continuum between them and share common characteristics with both. The Montney Formation provides a well-documented example of such a play, in which petroleum distribution is controlled by a combination of downdip increase of thermal maturity, fluid migration influenced by lateral and vertical permeability variations, and pressure compartmentalization. In this paper, we integrate publicly available data from thousands of wells within a well-defined stratigraphic framework to illustrate these regional and local controls on petroleum distribution in the Montney hybrid play. We demonstrate that produced gas compositional mapping is a powerful tool that complements comparatively sparse data from core- or cuttings-based organic geochemistry and petrography methods to provide an unparalleled level of detail of petroleum distribution at various scales. Coupling this compositional mapping with reservoir pressure data and published faults reveals a strong control of the structural framework on petroleum migration routes. The main targets of horizontal drilling in the Montney play are carrier beds that were charged by updip migrating petroleum and experienced further thermal maturation during the burial history. The relative contribution of different source rocks to this petroleum system remains speculative, and further investigation is needed to solve this conundrum.

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