Changes

Gas chromatography should never be used alone to make these interpretations. Supporting analytical data and geological information should be obtained as well. A combination of several processes (that is, multiple sources for oils and/or different thermal maturities) can make interpretation complex.

Gas chromatography should never be used alone to make these interpretations. Supporting analytical data and geological information should be obtained as well. A combination of several processes (that is, multiple sources for oils and/or different thermal maturities) can make interpretation complex.

==Applications==

==Applications==

Correlation of recovered fluids to other oils or source rock extracts can verify exploration models for development of new plays<ref name=pt05r154 /><ref name=pt05r81 />

Correlation of recovered fluids to other oils or source rock extracts can verify exploration models for development of new plays<ref name=pt05r154 /><ref name=pt05r81 />

* Allocation of production to specific intervals when production is commingled<ref name=pt05r87>Kaufman, R. L., Ahmed, A. S., Hempkins, W. B., 1987, A new technique for the analysis of commingled oils and its application to production allocation calculations: 16th Annual Convention Proceedings of the Indonesian Petroleum Association, p. 247–268.</ref>

* Allocation of production to specific intervals when production is commingled<ref name=pt05r87>Kaufman, R. L., Ahmed, A. S., Hempkins, W. B., 1987, A new technique for the analysis of commingled oils and its application to production allocation calculations: 16th Annual Convention Proceedings of the Indonesian Petroleum Association, p. 247–268.</ref>

For example, in a formation that has a continuous oil reservoir, the fingerprint of that oil does not change, in other words, a change in a fingerprint reflects a discontinuous reservoir. Therefore, by sampling reservoirs vertically and laterally, it is possible to determine reservoir continuity. Figure 6 shows a schematic drawing of two reservoir sands that actually define three separate reservoirs. Although geologically equivalent, sands A and B are discontinuous and should be produced as separate reservoirs. Sand C is laterally continuous but vertically discontinuous from both sands A and B. The star diagram shows a representation of the different oil fingerprints. If production from sands A and C in well 1 is commingled, production could be allocated to the individual sands by using the fingerprint differences with a binary mixing model<ref name=pt05r87 />. Figure 7 illustrates this with a simple mixing diagram.

For example, in a formation that has a continuous oil reservoir, the fingerprint of that oil does not change, in other words, a change in a fingerprint reflects a discontinuous reservoir. Therefore, by sampling reservoirs vertically and laterally, it is possible to determine reservoir continuity. [[:file:oil-and-condensate-analysis_fig6.png|Figure 6]] shows a schematic drawing of two reservoir sands that actually define three separate reservoirs. Although geologically equivalent, sands A and B are discontinuous and should be produced as separate reservoirs. Sand C is laterally continuous but vertically discontinuous from both sands A and B. The star diagram shows a representation of the different oil fingerprints. If production from sands A and C in well 1 is commingled, production could be allocated to the individual sands by using the fingerprint differences with a binary mixing model<ref name=pt05r87 />. [[:file:oil-and-condensate-analysis_fig7.png|Figure 7]] illustrates this with a simple mixing diagram.

 

[[file:oil-and-condensate-analysis_fig6.png|thumb|{{figure number|6}}Gas chromatographic data can be used to determine oil reservoir continuity in conjunction with other methods such as pressure-depth plots. Diagram on right shows a graphical comparison of chromatographic data.]]

 

[[file:oil-and-condensate-analysis_fig7.png|thumb|{{figure number|7}}A binary mixing diagram showing how the relative proportions of an unknown oil can be determined using the two end-member oils (separate zones) and laboratory mixtures.]]

In addition, if the fingerprint of oil from zone A, for example, is not found in the produced oil, this would indicate no production from zone A. The reason for lack of production could be depletion or watering out of a previously productive zone or the presence of a nonproductive or wet zone.

In addition, if the fingerprint of oil from zone A, for example, is not found in the produced oil, this would indicate no production from zone A. The reason for lack of production could be depletion or watering out of a previously productive zone or the presence of a nonproductive or wet zone.