Core Analysis Based on Vacuum Distillation
- Carrol M. Beeson (Petroleum Corporation of California) | Norris Johnston (Petroleum Corporation of California)
- Document ID
- Society of Petroleum Engineers
- Transactions of the AIME
- Publication Date
- December 1946
- Document Type
- Journal Paper
- 116 - 132
- 1946. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 4.1.2 Separation and Treating, 1.6.9 Coring, Fishing, 2 Well Completion, 5.6.2 Core Analysis, 1.6 Drilling Operations, 4.3.1 Hydrates, 2.4.3 Sand/Solids Control, 1.11 Drilling Fluids and Materials, 4.1.5 Processing Equipment, 5.2.1 Phase Behavior and PVT Measurements, 5.5.2 Core Analysis, 5.8.5 Oil Sand, Oil Shale, Bitumen
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The gravimetric-vacuum distillation method was developed to permit rapid andaccurate determinations of the oil-water ratios of small samples or sandscontaining little oil. In addition, the samples usually are so well cleaned andso little altered by the distillation at reduced pressure that rapidestimations of other physical properties may be made with the evacuatedcores.
Requiring only elementary glass-blowing technique, the distilling tubes andtraps used in determining oil-water ratios were easily fashioned from the usualglassware. A sketch and description are given of the necessary apparatus,including the cylindrical electrical heaters. The procedure, requiring about 40min., consists in raising the temperature and maintaining it between 6750 and725?F. for at least 10 min. while the pressure is held between 1 and 2 mm. Hg.The fluids condensed in the trap (cooled by a mixture of kerosine and solidcarbon dioxide) are separated in a centrifuge and the volume of water isrecorded. Determination of changes in weight with an analytical balance of allparts of the apparatus permits computation of weight of oil distilled and totalweight of oil recovered.
In determining the oil-water ratios of core samples, distillation atatmospheric pressure has proved to be sufficiently reliable for samplescontaining moderate quantities of oil. Since small samples and sands withlittle oil are encountered, however, it appeared advisable to develop a methodthat would be applicable under these circumstances.
The gravimetric-extraction procedure" 6-9 undoubtedly is very reliable andcould be used in all tests, but the time consumed in the determination wouldoften delay field operations. This would be especially true when dealing withtight sands or viscous oils, both of which retard the extraction process.
Accordingly, the gravimetric-vacuum distillation method was developed in orderto combine the good features of both of the older methods; that is, accuracyand speed. By reducing the pressure, it was found possible to perform thedistillation at a temperature that permits the use of glass apparatus, allparts of which can be weighed on an analytical balance. Thus, the fluids may beremoved quickly from the core, the water is readily trapped and measured, andthe loss in weight of the core is easily determined. In addition, the totalweight of material condensed in the distilling tube and in the trap provides amethod of determining the oil-water ratio that is practically independent ofthe one involving the loss in weight of the sample.
The use of vacuum not only permits as much accuracy as does the gravimetricextraction process, but it actually allows an increase in speed over theatmosphericdistillation method, because of the time required to cool the metalpots from about 1200?F between runs.
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