Changes

===Examples of biodegradation===

===Examples of biodegradation===

[[:file:oiloil-and-oilsource-rock-correlations_fig8-20.png|Figure 16]] (left) shows gas chromatograms of three oils from a common source in central Myanmar. A waxy oil (top) is sequentially converted into an extremely biodegraded remnant oil (bottom). The [http://wiki.aapg.org/Petroleum_reservoir_fluid_properties#API_specific_gravity API gravity] of the oil decreases and sulfur content increases substantially with increasing biodegradation.

[[:file:oiloil-and-oilsource-rock-correlations_fig8-20.png|Figure 16]] (left) shows gas chromatograms of three oils from a common source in central Myanmar. A waxy oil (top) is sequentially converted into an extremely biodegraded remnant oil (bottom). The [[API gravity]] of the oil decreases and sulfur content increases substantially with increasing biodegradation.

[[Pristane-phytane ratio]]s may also be affected slightly at low stages of biodegradation. At moderate levels these compounds are removed completely (left figure). The right figure below shows whole-oil gas chromatograms of three oils from the offshore [[Mackenzie Delta]], northwestern Canada, showing a modest decrease in the pristane-phytane ratio, apparently as the result of minor biodegradation.

[[Pristane-phytane ratio]]s may also be affected slightly at low stages of biodegradation. At moderate levels these compounds are removed completely (left figure). The right figure below shows whole-oil gas chromatograms of three oils from the offshore [[Mackenzie Delta]], northwestern Canada, showing a modest decrease in the pristane-phytane ratio, apparently as the result of minor biodegradation.