APIs

American Petroleum Institute, Bibliographies on Hydrocarbons, Vols. 1-4, "Vapor-Liquid Equilibrium Data for Hydrocarbon Systems" (1963), "Vapor Pressure Data for Hydrocarbons" (1964), "Volumetric and Thermodynamic Data for Pure Hydrocarbons and Their Mixtures" (1964), "Vapor-Liquid Equilibrium Data for Hydrocarbon-Nonhydrocarbon Gas Systems" (1964), API, Division of Refining, Washington. 

American Petroleum Institute Research Project 42, "Properties of Hydrocarbons of High Molecular Weight," API, Division of Science and Technology, New York, 1966. 

American Petroleum Institute, "Technical Data Book—Petroleum Refining," 3rd ed., API, Division of Refining, Washington, 1976. 

The results can be converted into an atmospheric TBP by using an equation equivalent to that proposed by Riazi and published by the API ... 

The API has recommended the use of a method to convert the D 2887 results into those of an ASTM D 86, developed by Riazi using the following... 

The effects of pressure are especially sensitive at high temperatures. The analytical expression [4.71] given by the API is limited to reduced temperatures less than 0.8. Its average error is about 5%. 

The coefficients A, B, C, D, E and F have been tabulated in the API technical data book for a great number of hydrocarbons. See Appendix 1. 

The solubility parameters calculated at 25°C have been tabulated for numerous hydrocarbons in the API technical data book. They can also by calculated by the relationship ... 

The constants k- enable the improved representation of binary equilibria and should be carefully determined starting from experimental results. The API Technical Data Book has published the values of constants k j for a number of binary systems. The use of these binary interaction coefficients is necessary for obtaining accurate calculation results for mixtures containing light components such as ... 

The flash curve at atmospheric pressure can be estimated using the results of the ASTM D 86 distillation by a correlation proposed by the API. For the same volume fraction distilled one has the following relation ... 

This calculation starts from the TBP at atmospheric pressure. The API recommends a relation established by Riazi (1982) ( oj j... 

The interfacial tension of a petroleum fraction at 20°C can be estimated by the following formula, cited by the API ... 

The average error is around 30%. This formula applies to pure substances and mixtures. For pure hydrocarbons, it is preferable to refer to solubility charts published by the API if good accuracy is required. 

Specific gravity is important commercially because the crude oil price depends partly on this property. The specific gravity is expressed most often in degrees API (see Chapters 1 and 4). 

Within the same geographicai region, the crude specific gravity varies from one reservoir to another, in Saudi Arabia, for example, the crude from the Ghawar field has an average standard specific gravity on the order of 0.850 (34° API) while the specific gravity of the crude from the nearby Safaniyah field is 0.893 (27° API). 

Within the same reservoir, we also observe variations of specific gravity from one well to another for example, 0.848 (38.4° API) and 0.861 (32.8° API) in the Ghawar field. 

The specific gravities of crudes fall generally between 0.800 and 1.000 as shown in Table 8.1, even though crudes having specific gravities outside this range exist 0.787 (48.2° API) for crudes in Barrow South, Alaska, USA and Santa Rosa, Venezuela and 1.028 (6° API) for the crude from Bradley Canyon, California, USA. 

Currently the charts used most often for this purpose are those published by the API. (Maxwell and Bonnel charts) from the Technical Data Book (see Chapter 4). 

Oil gravity is most commonly expressed in degrees API, a measure defined by the American Petroleum Institute as... 

The API gravity of water is 10°. A light crude oil would have an API gravity of 40°, while a heavy crude would have an API gravity of less than 20°. In the field, the API gravity is readily measured using a calibrated hydrometer. 

There are no definitions for categorising reservoir fluids, but the following table indicates typical GOR, API and gas and oil gravities for the five main types. The compositions show that the dry gases contain mostly paraffins, with the fraction of longer chain components increasing as the GOR and API gravity of the fluids decrease. 

Oil density at surface conditions is commonly quoted in API, as discussed in Section 5.2.3. 

The oil density at surface is readily measured by placing a sample in a cylindrical flask and using a graduated hydrometer. The API gravity of a crude sample will be affected by temperature because the thermal expansion of hydrocarbon liquids is significant, especially for more volatile oils. It is therefore important to record the temperature at... 

Internet address of the Laboratory (http //alphalma.cnrs-mrs.fr/pi/api.html)... 

Consider a triatomic system with the three nuclei labeled A, Ap, and Ay. Let the arrangement channel -1- A A be called the X arrangement channel, where Xvk is a cyclic permutation of apy. Let Rx,r be the Jacobi vectors associated with this arrangement channel, where r is the vector from A to and the vector from the center of mass of AyA to A . Let R i, rx be the corresponding mass-scaled Jacobi coordinates defined by... 

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