API MPMS 12.3:1996 pdf download.Manual of Petroleum Measurement Standards Chapter 12-Calculation of Petroleum Quantities Section 3-Volumetric Shrinkage Resulting From Blending Light Hydrocarbons With Crude Oils.
4 Data and Mathematical Model Selection
The data used to derive the correlation presented in this document originated from four separate experimental studies, authored by Childress, Scott, Schuchardt, and Booker. The ranges of density of oil and light hydrocarbon are given in Tablc I. The data arc described in more detail in Tables B-I to B-4. Available information on the sources and densities of crudes and light components is included, together with the number of data sets and summarized statistical data. Sources of the data arc also shown graphically in Figure B-I.
The selection of an appropriate mathematical model was based on the ability of different correlations to predict the experimental results. As expected from the form of the equation. API 2509C performs very poorly above a 25 percent spike. This is apparent from the large deviations between predicted and experimental values (i.e. the absolute residuals) plotted in Figure B-6.
Improvement was obtained by selecting the form of correlation equation proposed by Ashcroft et al.8 Figure B-6 shows the average absolute residuals determined using the model of Ashcroft et al., and Figure B-7 plots those obtained by fitting all of the data to an equation of the same form. Statistical differentiation between these latter two equations was achieved using an F-test as suggested by Beck and Arnold.10 This test confirmed that the new equation presented in this standard gives the best prediction of the available experimental data over the entire range of compositional variation.
Data sets that exhibited the anomalous behavior of expansion rather than shrinkage were not used in deriving the new correlation. This included Booker’s toluene and cyclohexanc spiked crude data sets and Schuchardt’s results from crude blends with gasoil.
The available expcrimcntal data were obtained at somewhat different temperatures and pressures. The older Childrcss and Scott data were obtained at 60°F and 100 psig, whereas the Booker and Schuchardt data apply to I Soc and ambient atmospheric pressure. Booker also reported results obtained at 25°C, but corrected these to 15°C using API correlations. The new correlation presented in this standard was derived from the data as presented in the referenced sources, with no attempt to normalize to a standard pressure and temperature. For the Booker data sets obtained at 25°C, the values corrected to 15°C, as given by Booker, were used.
5 Recommended Standard
5.1 STANDARD FOR CALCULATING SHRINKAGE
The standard is the printed tables in either SI or customary units found in Section 8 below. The equations uscd to generate the standard arc also provided (see Section 5.3) and can be used to dcvclop computer subroutines to replicate the results in the printed table.
API MPMS 12.3:1996 pdf download
