Density, S.G. and °API in Crude Oil
Density, S.G. and oAPI values are used to monitor the quality during the production and to establish the price in trading. The application describes the fully automatic measurement of density, S.G. and oAPI of light crude oil at 15°C and Heavy Crude oil at 90 °C and 50 °C.
Light and heavy crude oil show considerable differences in their chemical and physical properties. Accordingly, in order to test these products different methodological approaches may be required. While the light crudes often can be readily measured without heating treatment directly on the Density Meter, heavy crudes often need a heating treatment.
Density, S.G. and oAPI values are used to monitor the quality during the production and to establish the price in trading. API gravity (° API) relates the weight of oil to water. Depending on their origin crude oils can be very different in the chain lengths of hydrocarbons and the additional components (e.g. Sulphur) and, therefore, are grouped in two categories:
i) Light crude oil : Light crudes normally have a low density (e.g. below 900 kg/m3) and about 30° API and higher.
ii) Heavy crude oil : Heavy crudes, in contrast, can have densities above 1000 kg/m3 and less than 20° API
Light crudes can be measured directly on the density meter according to ASTM D5002. The sample is measured between 15 and 35°C and the integrated temperature compensation according to API tables transforms the density or specific gravity to either 15°C or 60°F.