Rheological Characterization and Viscosity Correlation for a 9.5 °API Extra-Heavy Crude Oil of the Southern Gulf of Mexico

The rheological behavior of a 9.5 °API extra-heavy dead crude oil produced in the southern Gulf of Mexico is experimentally investigated over the temperature range 30 °C≤T≤100 °C. Steady-shear measurements are used to characterize the stress–strain-rate response and apparent viscosity under controlled laboratory conditions representative of surface transport. Statistical analyses show that the oil exhibits a Bingham plastic behavior at 30 °C, transitions to a Herschel–Bulkley-type response at 50 °C, and displays a predominantly dilatant behavior at 100 °C. Existing dead oil viscosity correlations commonly used in field applications are evaluated against the experimental data and are found to systematically underpredict the viscosity by approximately one order of magnitude within the studied temperature range. Motivated by the observed exponential dependence of viscosity on temperature, a crude-specific viscosity–temperature correlation is proposed for this specific crude oil. The new correlation provides a significantly improved representation of the experimental data and leads to substantially more accurate pressure drop predictions in a representative pipeline transport scenario. The results highlight the importance of crude-oil-specific rheological characterization and viscosity modeling for reliable flow assurance analyses involving extra-heavy crude oils.