Changes

It has been all too common to base correlations entirely or mainly on geochemical considerations without proper regard for the geological content. While it is true that geochemical and geological considerations should be separated in the initial stages of a correlation study to ensure the geochemical conclusions are truly independent, the final story should fully integrate the geochemical model within the geologic framework. Although geochemical data can often give new insights, all geochemical conclusions must ultimately be consistent with the geologic facts. Failure to properly integrate geologic and geochemical data can lead to geochemically based correlations that are difficult or impossible to justify geologically.

It has been all too common to base correlations entirely or mainly on geochemical considerations without proper regard for the geological content. While it is true that geochemical and geological considerations should be separated in the initial stages of a correlation study to ensure the geochemical conclusions are truly independent, the final story should fully integrate the geochemical model within the geologic framework. Although geochemical data can often give new insights, all geochemical conclusions must ultimately be consistent with the geologic facts. Failure to properly integrate geologic and geochemical data can lead to geochemically based correlations that are difficult or impossible to justify geologically.

One of the best examples of such a discrepancy is in an early study of oils of the Michigan basin<ref name=ch08r56>Vogler, E., A., Meyers, P., A., Moore, W., A., 1981, Comparison of Michigan basin crude oils: Geochimica et Cosmochimica Acta, vol. 45, p. 2287–2293., 10., 1016/0016-7037(81)90078-8</ref> in which Devonian oils above the thick regional Silurian salt were correlated positively with Ordovician oils below the salt, without regard for the geologic problems involved in the proposed migration. Subsequent studies using more sensitive technology and larger numbers of samples show that the positive correlation was in fact fortuitous<ref name=ch08r21>Illich, H., A., Grizzle, P., L., 1983, Comment on “Comparison of Michigan basin crude oils” by Vogler: Geochimica et Cosmochimica Acta, vol. 47, p. 1151–1155., 10., 1016/0016-7037(83)90245-4</ref><ref name=ch08r43>Pruitt, J., 1983, Comment on “Comparison of Michigan basin crude oils” by Vogler: Geochimica et Cosmochimica Acta, vol. 47, p. 1157–1159., 10., 1016/0016-7037(83)90246-6</ref><ref name=ch08r58>Waples, D., W., 1985, Geochemistry in Petroleum Exploration: Boston, IHRDC, 232 p.</ref><ref name=ch08r47>Rullkötter, J., Meyers, P., A., Schaefer, R., G., Dunham, K., W., 1986, Oil generation in the Michigan basin: a biological marker and carbon isotope approach, in Leythaeuser, D., Rullkötter, J., eds., Advances in Organic Geochemistry 1985: Oxford, Pergamon, p. 359–376.</ref> and that migration through the salt had not occurred.

One of the best examples of such a discrepancy is in an early study of oils of the Michigan basin<ref name=ch08r56>Vogler, E., A., Meyers, P., A., Moore, W., A., 1981, Comparison of Michigan basin crude oils: Geochimica et Cosmochimica Acta, vol. 45, p. 2287–2293., 10., 1016/0016-7037(81)90078-8</ref> in which [[Devonian]] oils above the thick regional [[Silurian]] [[Evaporite|salt]] were correlated positively with [[Ordovician]] oils below the salt, without regard for the geologic problems involved in the proposed migration. Subsequent studies using more sensitive technology and larger numbers of samples show that the positive correlation was in fact fortuitous<ref name=ch08r21>Illich, H., A., Grizzle, P., L., 1983, Comment on “Comparison of Michigan basin crude oils” by Vogler: Geochimica et Cosmochimica Acta, vol. 47, p. 1151–1155., 10., 1016/0016-7037(83)90245-4</ref><ref name=ch08r43>Pruitt, J., 1983, Comment on “Comparison of Michigan basin crude oils” by Vogler: Geochimica et Cosmochimica Acta, vol. 47, p. 1157–1159., 10., 1016/0016-7037(83)90246-6</ref><ref name=ch08r58>Waples, D., W., 1985, Geochemistry in Petroleum Exploration: Boston, IHRDC, 232 p.</ref><ref name=ch08r47>Rullkötter, J., Meyers, P., A., Schaefer, R., G., Dunham, K., W., 1986, Oil generation in the Michigan basin: a biological marker and carbon isotope approach, in Leythaeuser, D., Rullkötter, J., eds., Advances in Organic Geochemistry 1985: Oxford, Pergamon, p. 359–376.</ref> and that [[migration]] through the salt had not occurred.

==See also==

==See also==