Changes

Hybrid systems are defined as those systems having a source rock combined with a higher abundance of organic-lean interbedded or juxtaposed nonclay lithofacies, for example, carbonates, silts, sands, or calcareous and argillaceous lime mudstones. As such, these hybrid resource systems have both source and nonsource intervals that allow access to gas in both lithofacies, although the nonsource lithofacies may be far more important because of its rock properties.  

Hybrid systems are defined as those systems having a source rock combined with a higher abundance of organic-lean interbedded or juxtaposed nonclay lithofacies, for example, carbonates, silts, sands, or calcareous and argillaceous lime mudstones. As such, these hybrid resource systems have both source and nonsource intervals that allow access to gas in both lithofacies, although the nonsource lithofacies may be far more important because of its rock properties.  

Although organic-rich mudstone systems commonly have a substantial organic porosity component, hybrid systems may have no organic porosity; they have predominantly matrix porosity or, in some cases, fracture porosity. The Triassic Doig Phosphate and Montney formations from the Western Canada sedimentary basin illustrate one such difference in organic richness and storage capacities in a mudstone versus a hybrid shale resource system. The Doig Phosphate is an organic-rich mudstone and has reasonably good correlation of bulk volume porosity to TOC, whereas the Montney Shale shows an inverse and poor correlation ([[:File:M97FG2.jpg|Figure 2]]). In the case of the Doig Phosphate, this implies that organic porosity is the primary storage mechanism formed as a result of organic matter decomposition.<ref name=Jrvie2006 /> However, the Montney Shale relies primarily on matrix porosity of petroleum expelled from organic-rich shales either within the Montney or from other sources (Riediger et al., 1990). Other hybrid systems are a theme and variation of this; for example, the hybrid Eagle Ford Shale system is more aptly described as a calcareous or argillaceous lime mudstone with high TOC, and it has a high interbedded carbonate content (typically sim60%) that provides additional matrix storage capacity in intimately associated (juxtaposed) carbonates.

Although organic-rich mudstone systems commonly have a substantial organic porosity component, hybrid systems may have no organic porosity; they have predominantly matrix porosity or, in some cases, fracture porosity. The Triassic Doig Phosphate and Montney formations from the Western Canada sedimentary basin illustrate one such difference in organic richness and storage capacities in a mudstone versus a hybrid shale resource system. The Doig Phosphate is an organic-rich mudstone and has reasonably good correlation of bulk volume porosity to TOC, whereas the Montney Shale shows an inverse and poor correlation ([[:File:M97FG2.jpg|Figure 2]]). In the case of the Doig Phosphate, this implies that organic porosity is the primary storage mechanism formed as a result of organic matter decomposition.<ref name=Jrvie2006 /> However, the Montney Shale relies primarily on matrix porosity of petroleum expelled from organic-rich shales either within the Montney or from other sources.<ref>Riediger, C. L., M. G. Fowler, P. W. Brooks, and L. R. Snowdon, 1990, Triassic oils and potential Mesozoic source rocks, Peace River arch area, western Canada Basin: Organic Geochemistry, v. 16, no. 1–3, p. 295–305, doi:10.1016/0146-6380(90)90049-6.</ref> Other hybrid systems are a theme and variation of this; for example, the hybrid Eagle Ford Shale system is more aptly described as a calcareous or argillaceous lime mudstone with high TOC, and it has a high interbedded carbonate content (typically sim60%) that provides additional matrix storage capacity in intimately associated (juxtaposed) carbonates.

==Organic richness: total organic carbon assessment==

==Organic richness: total organic carbon assessment==

* Raseroka, L., and I. R. McLachlan, 2009, [http://www.searchanddiscovery.net/documents/2009/10196raseroka/index.htm?q=%2Btext%3Araseroka The petroleum potential of South Africa's onshore Karoo basins (abs.)]: AAPG International Conference and Exhibition, Cape Town, South Africa, October 26–29, 2008, Search and Discovery Article 10196, 3 p.

* Raseroka, L., and I. R. McLachlan, 2009, [http://www.searchanddiscovery.net/documents/2009/10196raseroka/index.htm?q=%2Btext%3Araseroka The petroleum potential of South Africa's onshore Karoo basins (abs.)]: AAPG International Conference and Exhibition, Cape Town, South Africa, October 26–29, 2008, Search and Discovery Article 10196, 3 p.

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* Riediger, C. L., M. G. Fowler, P. W. Brooks, and L. R. Snowdon, 1990, Triassic oils and potential Mesozoic source rocks, Peace River arch area, western Canada Basin: Organic Geochemistry, v. 16, no. 1–3, p. 295–305, doi:10.1016/0146-6380(90)90049-6.

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* Rullkotter, J., et al., 1988, Organic matter maturation under the influence of a deep intrusive heat source: A natural experiment for quantitation of hydrocarbon generation and expulsion from a petroleum source rock (Toarcian Shale, northern Germany): Advances in Organic Geochemistry 1987: Organic Geochemistry, v. 13, no. 1–3, p. 847–856, doi:10.1016/0146-6380(88)90237-9.

* Rullkotter, J., et al., 1988, Organic matter maturation under the influence of a deep intrusive heat source: A natural experiment for quantitation of hydrocarbon generation and expulsion from a petroleum source rock (Toarcian Shale, northern Germany): Advances in Organic Geochemistry 1987: Organic Geochemistry, v. 13, no. 1–3, p. 847–856, doi:10.1016/0146-6380(88)90237-9.

* Rushing, J. A., A. Chaouche, and K. E. Newsham, 2004, A mass balance approach for assessing basin-centered gas prospects: Integrating reservoir engineering, geochemistry, and petrophysics, in J. M. Cubitt, W. A. England, and S. R. Larter, eds., Understanding petroleum reservoirs: Toward an integrated reservoir engineering and geochemical approach: Geological Society (London) Special Publication 237, p. 373–390.

* Rushing, J. A., A. Chaouche, and K. E. Newsham, 2004, A mass balance approach for assessing basin-centered gas prospects: Integrating reservoir engineering, geochemistry, and petrophysics, in J. M. Cubitt, W. A. England, and S. R. Larter, eds., Understanding petroleum reservoirs: Toward an integrated reservoir engineering and geochemical approach: Geological Society (London) Special Publication 237, p. 373–390.