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* Pertinent neighboring wells, if sampling is permitted
* Pertinent neighboring wells, if sampling is permitted
The expected character of the petroleum (such as API gravity and gas to oil ratio) and reservoir conditions (such as pressure and temperature) must be considered so that representative samples can be obtained. Changes in pressure and flow rate during well testing can alter petroleum composition and physical properties. In addition, samples of drilling mud, load and kill fluids, drilling additives, and wellsite fuel oils and lubricants should be kept until petroleum analyses are completed. If contamination is discovered or suspected, these samples can be analyzed and compared to recovered “petroleum.”
The expected character of the petroleum (such as [[API gravity]] and gas to oil ratio) and reservoir conditions (such as pressure and temperature) must be considered so that representative samples can be obtained. Changes in pressure and flow rate during well testing can alter petroleum composition and physical properties. In addition, samples of drilling mud, load and kill fluids, drilling additives, and wellsite fuel oils and lubricants should be kept until petroleum analyses are completed. If contamination is discovered or suspected, these samples can be analyzed and compared to recovered “petroleum.”
For drilling wells, all recovered fluids should be sampled, including shows, oil on the pits, DSTs, and formation tests. Drill cuttings and core samples may be solvent extracted to obtain liquid samples. For completed wells, each zone test should be sampled before, during, and after [[workovers]], and prior to abandonment. For reservoir continuity studies or production allocation, samples should be collected as necessary.
For drilling wells, all recovered fluids should be sampled, including shows, oil on the pits, DSTs, and formation tests. Drill cuttings and core samples may be solvent extracted to obtain liquid samples. For completed wells, each zone test should be sampled before, during, and after [[workovers]], and prior to abandonment. For reservoir continuity studies or production allocation, samples should be collected as necessary.
The most commonly run analyses performed on bulk samples are
The most commonly run analyses performed on bulk samples are
* API gravity
* ]]API gravity]]
* Viscosity
* Viscosity
* Pour point
* Pour point
===Molecular composition===
===Molecular composition===
<gallery mode=packed heights=300px widths=300px>
<gallery mode=packed heights=300px widths=300px>
file:oil-and-condensate-analysis_fig2.png|{{figure number|2}}Gas chromatograms of a “normal” 35° API gravity oil and a biodegraded oil showing the lose of aliphatics (n-paraffins and isoprenoids) due to biodegradation.
file:oil-and-condensate-analysis_fig2.png|{{figure number|2}}Gas chromatograms of a “normal” 35° ]]API gravity]] oil and a biodegraded oil showing the lose of aliphatics (n-paraffins and isoprenoids) due to biodegradation.
file:oil-and-condensate-analysis_fig3.png|{{figure number|3}}Gas chromatography can be used to determine geological processes experienced by an oil.
file:oil-and-condensate-analysis_fig3.png|{{figure number|3}}Gas chromatography can be used to determine geological processes experienced by an oil.
file:oil-and-condensate-analysis_fig4.png|{{figure number|4}}Gas chromatogram showing drilling mud contamination to a biodegraded oil.
file:oil-and-condensate-analysis_fig4.png|{{figure number|4}}Gas chromatogram showing drilling mud contamination to a biodegraded oil.