AAPG Annual Convention and Exhibition

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Experimental Workflow Applied to Marine Source Rocks Sampled in the Montney-Doig Formations of the Western Canada Sedimentary Basin


Oil and gas in the Montney-Doig succession in the Western Canada Sedimentary Basin have been produced conventionally for decades from proximal deposits and turbiditic reservoirs. But in recent years, tight organic-lean and organic-rich fine-grained sediments from the distal part of the basin have become the most active unconventional play in Canada. The present-day distribution of hydrocarbons within the Montney-Doig system results from the interplay of the stratigraphic architecture that controls the spatial distribution of facies heterogeneity and organic matter, with the structural evolution of the basin that controls the burial history and timing of fluid migrations. Integrating these different elements at basin scale would help better define play concepts and reduce the exploration risk of this complex petroleum system. This integration is performed in a specific workflow designed for low permeability formations and must include some important characterization such as pore size distribution as well as hydromechanical properties. In this presentation, we show a series of source-rock sampled in the Montney-Doig source rock intervals, that have been characterised in the laboratory in terms of porosity content, mechanical, petrophysical and geochemical properties. Such characterization are not trivial in low permeability formations due the small pore sizes ranging from nano-meters up to micro-meters. Experimental techniques requires various samples sizes and can be destructive; therefore an appropriate sequence must be chosen. For the various characterization, we used the most appropriate and up to date methods: NMR for porosity, NMR cryoporometry and mercury injection for pore size distribution, fast gas and water permeability steady state measurement including confinement effects, pressure dependant petroacoustic tests, tensile strength measurements (Brazilian tests), geochemical tests (RockEval) and mineral composition analysis. The findings are discussed in terms of their impacts on the storage capacity and the transport of hydrocarbons fluids in this unconventional reservoir.