Crude oil density

Figure 1.2 Specific gravity of petroleum fractions. (Plotted from data in J. B. Maxwell, Crude Oil Density Curves, Data Book on Hydrocarbons, D. Van Nostrand, Princeton, NJ, 1957, pp. 136-154.)...

Density is the mass (weight) of a given volume of oil and is typically expressed in grams per cubic centimetre (g/cm3). It is the property used by the petroleum industry to define light or heavy crude oils. Density is also important because it indicates whether a particular oil will float or sink in water. As the density of water is 1.0 g/cm3 at 15°C and the density of most oils ranges from 0.7 to 0.99 g/cm3, most oils will float on water. As the density of seawater is 1.03 g/cm3, even heavier oils will usually float on it. The density of oil increases with time, as the light fractions evaporate. 

Crude oil density ranges from types that are heavier than water. Some California crudes have an API reading of 5°-7°. Crude oils of 10°API is found in Venezuela and up to 60° API in other areas. Most crude oil averages 27° to 35° API. 

Crude oil (density 800kgm, viscosity 4 x 10 Pas) is pumped through a... 

Although crude oil density, sulfur and viscosity are the minimum typical bulk properties required by the model, sometimes optional laboratory analysis may be required to improve the accuracy of the predictions. The methodology is independent of the available information for the crude oil, and partial crude oil assays can be used. The output information is always a complete updated assay. 

The crude oil density p(P,T) can be calculated by using the correlation of Standing-Katz ... 

P(Pq. Tq) is the crude oil density at standard conditions, that is, 14.7 psia and 60°F Ap is the density correction for compressibility of oils (psia)... 

Eleven different groups of crude oils haye been defined according to the densities of their heavy gasoline cuts (100-200°C) and their residues with boiling points above 350°C as shown in Table 3.1. 

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... 

The most relevant parameters in pipeline transportation of heavy crude oil are velocity, viscosity, temperature, density, and pour point [691]. Heavy crude... 

In the present paper, interfacial tensions were measured for a number of heavy crude oils at temperatures up to 200°C using the spinning drop technique. However, reliable data cannot be obtained by this or any other drop shape method because of the small density difference between heavy crudes and water which, moreover, tends to decrease as the temperature increases. This problem was overcome by using aqueous D20 instead of H20 as has been previously described [5,8,211. The influence of surfactant type and concentration, mono- and divalent cation concentrations, and pH on the attainment of low interfacial tensions are reported and discussed. 

Materials. Samples of dewatered crude oils were obtained from the Athabasca oil sands of the McMurray formation by extraction using the commercial hot water process (Suncor Inc.) the Bl uesky-Bu11 head formation at Peace River, Alberta by solvent extraction of produced fluids the Clearwater formation at Cold Lake, Alberta by solvent extraction of core material and the Karamay formation in Xing-Jiang, China. A summary of the physical and chemical properties of the crude oils, including chemical composition, and density-temperature and viscosity-temperature relationships, is given in Table I. 

Densities were measured using a Paar DMA 60 meter equipped with DMA 512 and DMA 601 HP external cells. Values in the 50-150°C range were interpolated from measured data (3-5 points) values above 150°C were extrapolated and are less accurate. Interfacial tension measurements at the minimum density difference encountered (0.05 g/cm3) could be in error by as much as 10%, which is within the repeatability of measurements with heavy crude oil samples (see below). 

Crude Oils and Connate Water. The multiple micellar slug process was developed for the tertiary recovery of three light oils viz. Bradford crude, Bonnie Glen crude and Provost crude. The viscosities and densities of the three crude oils used are listed in Table I. 

The effectiveness of C02 in displacing oil from reservoirs is marred, however, by its extremely low viscosity. The viscosity of dense C02 remains low (in the range from 0.03 to 0.08 cp or 0.03 to 0.08 mpa) despite its relatively high density (above 0.45 g/cm3) under reservoir conditions. This low viscosity of C02 as compared to that of crude oil (1-10 cp) results in a high mobility ratio which degrades the macroscopic efficiency of the displacement process. Therefore, some method of mobility control is required for efficient use of C02, to increase greatly the quantity of producible oil. 

Methodology Various fraction of crude oil was distilled under different condition after being sonicated by an ultrasonic processor for different intervals of time. Density of these fractions was determined by dialatometer. Viscosities of these fractions were measured using Ubbelohde viscometer and the results given as under ... 

Result The recovery of different fractions of petroleum distillate under atmospheric pressure was more than under reduced pressure because at lower pressure the vapour pressure of lighter molecule of crude oil increased so that they were siphoned out from the system without being condensed. Whereas a combination of distillation of lighter fraction under normal atmospheric pressure followed by the distillation of heavier contents under reduced pressure showed an improvement in the recovery of petroleum products. Recovery of distillates was still more when crude oil was first sonicated and then distilled under normal and reduced pressures. The viscosity of distillate increased with sonication whereas there was a decrease in value of density. 

Compute the pressure in the pipe at the location shown on Figure 4-17. The flow rate through the pipe is 10,000 L/hr. The pipe is commercial steel pipe with an internal diameter of 50 mm. The liquid in the pipe is crude oil with a density of 928 kg/m3 and a viscosity of 0.004 kg/m s. The tank is vented to the atmosphere. 

Their bulk properties as well as their chemical composition can characterize crude oils. Distillation of cmde oil provides fraction profiles over a certain boiling range. The crude oil as well as the distillation fractions can be described in terms of density, viscosity, refractive index, sulfur content, and other bulk parameters. 

The kerogen content of different oil shales, i.e., the average yield of oil of an oil shale can vary greatly. Most oil shales have oil yields between 50 and 150 1 oil/t oil shale, rich shales may even yield more than 200 1/t. A particular characteristic of oil shale is its high areal density, which can exceed 1 million b/acre at its thickest (Bunger et al., 2004). Oil shale can also be used directly as fuel for electricity generation, as, for instance, in Estonia. However, oil shale is characterised by a low calorific value between 7.5 and 9 MJ/kg (based on LHV), which is about one fifth of the energy content of crude oil (Porath, 1999). 

Table 2.2. Variation of Density and API Gravity, and Residuum Content for Selected Crude Oils...

Accurate determination of the density or specific gravity of crude oil is necessary for the conversion of measured volumes to volumes at the standard temperature of 15.56°C (60°F) (ASTM D1250 IP 200 Petroleum Measurement Tables). The specific gravity is also a factor reflecting the quality of crude oils. 

The density of crude oil is on the order of 0.85 g/cm, so if the sea surface is calm, an oil spill will initially form a slick. The slick is subject to physical processes, such as advection and turbulence, causing it to move vertically and/or horizontally. Advection tends to lead to dispersal or, if land is nearby, shoreline stranding. Turbulence promotes the formation of emulsions, called chocolate mousse, which can be transformed via weathering into tarballs. The lower-molecular-weight compounds tend to evaporate or dissolve. Some fractions of petroleum have solubilities in seawater on the order of tens of milligrams per liter. Some are also photochemically oxidized. 

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