Andrade’s   method is based on the observation that the logarithm of viscosity plotted vs. reciprocal absolute temperature forms a linear relationship from somewhat above the normal boiling point to near the freezing point of the oil, as Fig. 6 shows. Andrade’s method is applied through the use of measured dead oil viscosity data points taken at low pressure and two or more temperatures. Data should be acquired at temperatures over the range of interest. This method is recommended when measured dead oil viscosity data are available.
Perl is a modern, flexible, multi-purpose scripting language anybody can learn. We use it to automate many repetitive tasks, like compiling this page of references. Though Perl scripts can be horribly cryptic, this should not hold you back from using them: You can just run them without knowing what's inside, like you'd do with any old fashioned executable! The only thing you need to know is how to use the commandline, and that is nothing to be afraid of! For any information on Perl http:// is the best place to start looking. Perl is installed by default on many a mature operating system, for example Linux. Unfortunately, MS windows requires you to install it yourself. We use ActiveState 's Perl for windows (once installed, run the scripts from the commandline by starting a "DOS" box by going to "Start"-"Run" and typing "Cmd" or "Command" on Win95). Useful Perl links can be found at the end of the Perl Timeline page and on http:// .
Nonhydrocarbon gases typically found in crude oil systems are nitrogen, carbon dioxide, and hydrogen sulfide. The bubblepoint pressure correlations (with the exception of Owolabi,  Al-Marhoun,   and Dokla and Osman  ) were developed with crude oil systems that did not contain significant amounts of impurities in the gas phase. Work by Jacobson,  Glasø,  and Owolabi point out the need for procedures to modify the calculated bubblepoint pressure for these impurities. Nitrogen does not readily dissolve in crude oil, resulting in an increase in bubblepoint pressure. On the other hand, carbon dioxide and hydrogen sulfide are more soluble in crude oil than natural gas, which has the effect of lowering bubblepoint pressure. Jacobson evaluated 110 crude oil PVT samples containing up to 14% nitrogen and found that a correction factor need only be based on the nitrogen content of the gas and the temperature of the mixture. An equation to account for the effects of nitrogen on bubblepoint pressure was developed.