Journal of Petroleum Science and Engineering 57 (2007) 166 – 180 www.elsevier.com/locate/petrol
Classification and characterisation of crude oils based on distillation properties
Peter Behrenbruch ⁎, Thivanka Dedigama
Australian School of Petroleum, University of Adelaide, Australia 5005 Accepted 31 October 2005
Abstract True boiling point (TBP) distillation is a widely used batchdistillation process for the characterisation of crude oils, traditionally mainly for marketing and refining purposes. The TBP curve is obtained by plotting the cumulative mass or volume distillation fraction with increasing temperature. The shape of these curves is dependent on the volatility of components in a given crude oil. As such, these curves give a “footprint” of the composition of crude oils. Anew method of characterising crude oils based on the shape of TBP distillation curves is proposed. A gamma distribution is used to characterise the TBP distillation curve, and the parameters of the fitted distribution are used as characterisation parameters. The proposed method is found to describe experimental data very well with just two parameters, and as such offers a very practical approachin terms of classifying crude oils. Ranges of values for the characterisation parameters for different types of crude oil are identified for a large set of TBP data. The characterisation parameters can be correlated with a number of crude oil properties. They can also be used to predict the petroleum fractions that can be produced from a given crude oil and hence correlated to the value of thatcrude. As an alternative, it is shown how crude oil cut fractions may be classified with the aid of a ternary diagram, and the link between this approach and the characterisation parameters introduced above is demonstrated. © 2006 Elsevier B.V. All rights reserved.
Keywords: True boiling point distillation; Crude oil; Characterisation; Classification; Gamma distribution; Ternary diagram
1.Introduction Petroleum has an organic origin based on the accumulation of plant and animal matter and the action of heat and pressure over a long period of time on this biological material. It is a complex mixture of hydrocarbons that naturally occurs in reservoir rocks. Petroleum encompasses liquid hydrocarbons referred
⁎ Corresponding author. Tel.: +61 8 8303 8020; fax: +61 8 8303 8011. E-mailaddress: email@example.com (P. Behrenbruch). 0920-4105/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.petrol.2005.10.016
to as crude oil, natural gas and solid hydrocarbons such as tars. The chemical constituents of petroleum and techniques available to separate and analyse the various compounds are discussed in Waples (1985). Major groups of compoundsfound in petroleum are saturated hydrocarbons, including straight chained, branched and cyclic hydrocarb ons, simple aromatic hydrocarbons, small sulphur bearing compounds, resins and very large aromatic asphaltene compounds. The varied composition of petroleum has led to the existence of a number of characterisation systems. Each of these characterisation systems is important for decision makingat some stage of exploration, production
P. Behrenbruch, T. Dedigama / Journal of Petroleum Science and Engineering 57 (2007) 166–180 Table 1 List of TBP distillation data (source: Chevron, 2005) Country Location Crude oil Date of assay 2000 1996 2001 2001 2002 2002 2002 2000 2000 1995 1987 1998 1997 2001 1994 1997 1999 2000 2002 2000 2000 1999 1994 2003 Whole crude properties Gravity (°API)19.2 32.8 39.3 38.4 20.5 37.7 46.8 35.8 34.4 35.0 38.0 48.1 61.2 41.3 20.8 35.3 45.1 40.1 43.0 43.3 35.9 36.0 35.2 26.0 Specific gravity 0.9390 0.8610 0.8282 0.8329 0.9308 0.8365 0.7936 0.8459 0.8528 0.8497 0.8346 0.7877 0.7344 0.8189 0.9293 0.8482 0.8014 0.8246 0.8108 0.8094 0.8454 0.8447 0.8486 0.8987 Characterization factor (K factor) 11.6 12.3 12.2 12.1 12.0 12.2 12.4 11.9 11.7 11.7 11.7...
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