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* Analyzing geohistory or mapping maturation indicators can identify reservoir maturation levels where methane accumulations may be uneconomic. Most sizable gas accumulations occurring at maturation levels > 2.8% R<sub>o</sub> have thick claystone seals that help preserve the accumulation.
 
* Analyzing geohistory or mapping maturation indicators can identify reservoir maturation levels where methane accumulations may be uneconomic. Most sizable gas accumulations occurring at maturation levels > 2.8% R<sub>o</sub> have thick claystone seals that help preserve the accumulation.
* Presence of intrusives in the fetch area can indicate a potential for carbon dioxide dilution (e.g., .<ref name=ch11r29>Parker, C., 1974, Geopressures and secondary [[porosity]] in the deep Jurassic of Mississippi: Transactions of the Gulf Coast Association of Geological Societies, vol. 24, p. 69–80.</ref>
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* Presence of intrusives in the fetch area can indicate a potential for carbon dioxide dilution.<ref name=ch11r29>Parker, C., 1974, Geopressures and secondary [[porosity]] in the deep Jurassic of Mississippi: Transactions of the Gulf Coast Association of Geological Societies, vol. 24, p. 69–80.</ref>
 
* If reservoir rocks are associated with evaporite cements or beds, expect hydrogen sulfide if the reservoir is exposed to temperatures > [[temperature::150&deg;C]] and iron is not present to remove the hydrogen sulfide.
 
* If reservoir rocks are associated with evaporite cements or beds, expect hydrogen sulfide if the reservoir is exposed to temperatures > [[temperature::150&deg;C]] and iron is not present to remove the hydrogen sulfide.
 
* Nitrogen is released during the late stages of coal maturation.<ref name=ch11r18>Jüntgen, V., H., Karweil, J., 1966, Gasbildung and gasspeicherung in steinkohlenfluzen, I. gasbildung: Erdöl und Kohle-Erdgas-Petrochemie, vol. 19, p. 339–344.</ref> Therefore, if a prospect is charged by a type III source rock only during its late maturation stage (R<sub>o</sub> > 2.5%), nitrogen dilution is possible. High nitrogen gas content is also characteristic of evaporative settings and hydrocarbon-poor basins.
 
* Nitrogen is released during the late stages of coal maturation.<ref name=ch11r18>Jüntgen, V., H., Karweil, J., 1966, Gasbildung and gasspeicherung in steinkohlenfluzen, I. gasbildung: Erdöl und Kohle-Erdgas-Petrochemie, vol. 19, p. 339–344.</ref> Therefore, if a prospect is charged by a type III source rock only during its late maturation stage (R<sub>o</sub> > 2.5%), nitrogen dilution is possible. High nitrogen gas content is also characteristic of evaporative settings and hydrocarbon-poor basins.

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