Determining Water Content in Crude Oils – Mr. Bruce Williams of ITS Caleb Brett presented an overview of the test methods used for water determination and factors affecting their precision and accuracy. Please see Attachment 2. Water and sediment by Centrifuge is the most widely used test but it is easy to get wrong results by improper reading of the instrument, by failure to complete the centrifugation, and by the formation of an emulsion layer. Water by Distillation is a lab method and has its own set of problems, such as improper reading of the results, improper cleaning which results in water being retained on the glassware and not included in the results, and not completing the process that forces the water into the measurement chamber. Karl Fischer, although very accurate if properly performed, can also yield wrong results if the titrant strength is not uniform, if the sample is incorrectly measured, from interference in the crude, and from improper calibration. All the test methods share one common problem, poor sampling. Water has a tendency to settle making proper sample preparation critical. Also, water forms emulsions in crude which can be very difficult to break and cause some water to go undetected.

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ASTM Crosscheck Results - Clifford Mills of Conoco presented graphs of the five ASTM runs thus far.  Both of the tests represented, D4006 and D4928, show considerable variance from published precision information.

Conoco Water and Sediment Results - Clifford also presented Conoco experiences in water and sediment measurement.  In many instances, the combination of Karl Fischer water and sediment by filtration tracked very well to the field centrifuge determination of S&W. Karl Fischer detected more water in almost every instance, but the field determination of solids, via centrifuge, was much higher than the lab procedure. Therefore, the total (solid and water) centrifuge reading was not that far off from the lab determination. Part of this phenomenon can be attributed to the fact that solids usually contain a great deal of water and it is sometimes hard to distinguish between a wet solid and water.

Other Pipelines - Patti Edens of Shell Pipeline indicated that they are still interested in Karl Fischer water measurement. Shell feels they have solved the solvent disposal problem (KF solvent is designated a hazardous waste) but need to work on the sediment issue and the fact that field KF equipment is not approved for use in a hazardous area.