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Liquid Hydrocarbon (crude oil) Lab Analysis


Glass Hydrometer Method (ASTM D-1298)

  • For stabilized hydrocarbon sample (preferred method)
  • ASTM D-1298
  • Stabilized liquid hydrocarbon sample is cooled to approximately 15°C or 60°F (depending on the liquid pour point) and transferred into a hydrometer jar.
  • Find observed density and temperature
  • Correct observed density to 15°C – as per ASTM D1250 Table 53.
  • Glass hydrometer and thermometer shall be certified by legal (authorized) governing body.

Digital Density Meter Method

  • For stabilized hydrocarbon sample
  • A known volume of liquid sample is introduced into an oscillating sample tube.
  • The change in the oscillating frequency caused by the change in the mass of the tube is used in conjunction with the calibrated date to determine the density of sample.
  • Convert to @ 15°C
  • Equipment shall be certified by legal (authorized) governing body.

BS&W Analysis

Water Fisher Titration Standards

  • ASTM D-4377 : Karl Fisher Titration
  • ASTM D-4928 : Coulometric Karl Fisher

The sediment content in the sample

  • analysed in accordance to membrane filtration or by extraction method;
  • must be added to water determined by this method to obtained total BS&W content.

Known mass of homogenized liquid sample is injected into the Karl Fisher analytical instrument and tiltrated to an electromagnetic end point to determine the mass% of water.

The Karl Fisher instrument used shall be calibrated against sample on a mutually agreed frequency.


BS&W Analysis by Centrifuge


  • ASTM D-4007 : Using heated centrifuge
  • ASTM D-1796 : Non-heated centrifuge

Equal volumes of samples and solvent (water saturated toluene) are placed into a cone-shaped graduated centrifuge tube.

After centrifuging, the volume of the higher gravity BS&W layer @ the bottom of the tube is read.

Reading shall be reported as BS&W in volume%.


BS&W Analysis by Membrane Filtration


ASTM D-4807

The sediment content in the sample analyzed by this method must be added to the water determined by Fisher Titration/distillation to obtained the total BS&W content.

A portion of a representative crude oil samples is dissolved in hot toluene and filtered under the vacuum through a 0.45 micron porosity membrane filter.

The filter with residue is washed, dried and weighted to give the final sediment content in weight %.

The mass of residue, calculated as a % is reported as sediment by extraction.


Determination of moisture in live crude

By Coulometric Karl Fisher method. The water content is determine using ASTM D-4928.

  • Unstabilized crude
  • the pressurized sample is homogenized by shuttling the internal piston back and forth by applying a pressure different.
  • Then, a representation sub-sample is removed from the receiver using a pressure syringe via the septum port.

Categories: Oil & Gas Notes

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