Changes

==Maturity effects==

==Maturity effects==

[[file:oiloil-and-oilsource-rock-correlations_fig8-2.png|thumb|300px|{{figure number|1}}set of southern California oils showing wide variation in both gravity and sulfur content. Copyright: Kennicutt and Brooks (1988); courtesy Oil & Gas Journal.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-2.png|thumb|300px|{{figure number|1}}set of southern California oils showing wide variation in both gravity and sulfur content. Copyright: Kennicutt and Brooks;<ref name=KennicuttBrooks1988>Kennicutt, M. C., and J. M. Brooks, 1988, Surface geochemical exploration studies predict API gravity off California: Oil & Gas Journal, September 12, p. 101–106.</ref> courtesy Oil & Gas Journal.]]

The trend in sulfur content within a single megafamily of high-sulfur oils is a function of API gravity, which normally increases with increasing maturity. Thus, highly mature oils that were originally high in sulfur (e.g., from a carbonate source) can have low sulfur content, as evidenced in the figure below. Therefore, unless the maturity levels of all samples are similar, or unless some correction for maturity is made, sulfur content can be misleading as a correlation parameter. Sulfur content decreases with increasing maturity (API gravity) in low-sulfur oils as well, although the range of variation is usually too small to be of much practical value.

The trend in sulfur content within a single megafamily of high-sulfur oils is a function of API gravity, which normally increases with increasing maturity. Thus, highly mature oils that were originally high in sulfur (e.g., from a carbonate source) can have low sulfur content, as evidenced in the figure below. Therefore, unless the maturity levels of all samples are similar, or unless some correction for maturity is made, sulfur content can be misleading as a correlation parameter. Sulfur content decreases with increasing maturity (API gravity) in low-sulfur oils as well, although the range of variation is usually too small to be of much practical value.

[[:file:oiloil-and-oilsource-rock-correlations_fig8-2.png|Figure 1]] is a set of southern California oils showing wide variation in both gravity and sulfur content. Several workers attribute this relationship to factors such as [[migration]] and maturity differences, as well as to source variations.<ref name=ch08r36>Orr, W., L., 1986, Kerogen/asphaltene/sulfur relationships in sulfur-rich Monterey oils: Organic Geochemistry, vol. 10, p. 499–516., 10., 1016/0146-6380(86)90049-5</ref>

[[:file:oiloil-and-oilsource-rock-correlations_fig8-2.png|Figure 1]] is a set of southern California oils showing wide variation in both gravity and sulfur content. Several workers attribute this relationship to factors such as [[migration]] and maturity differences, as well as to source variations.<ref name=ch08r36>Orr, W. L., 1986, Kerogen/asphaltene/sulfur relationships in sulfur-rich Monterey oils: Organic Geochemistry, vol. 10, p. 499–516., 10., 1016/0146-6380(86)90049-5</ref>

==Gross composition==

==Gross composition==