Investigation of volumetric fluid properties of (heptane + hexadecane) at reservoir conditions

• New density data for heptane + hexadecane were measured by an Anton Paar densimeter.
• Pressures and temperatures ranged from 0.3 to 45 MPa and 313 to 393 K, respectively.
• Excess molar volume, isothermal compressibility and isobaric expansion were derived.
• The results indicate the non-ideal behavior of the mixture.

The paraffin group has a major role in the surface properties of hydrocarbon reservoirs. Because of its importance, this work reports new experimental density data for binary mixtures of heptane + hexadecane at temperatures and pressures ranging from 313.15 to 393.15 K, and 0.34 to 44.47 MPa, respectively. Five compositions were investigated, consisting of pure heptane, pure hexadecane, and their binary mixtures at heptane mole fractions of 0.4296, 0.6932, and 0.8748. An Anton Paar vibrating-tube densimeter was used to measure the densities. The resulting density data were fit to a Tait-type equation, showing deviations of less than 0.12% in AAD%. Excess volumes were calculated from the experimental data and fit to the Redlich–Kister equation. In addition, partial molar volumes of the components at infinite dilution and excess partial molar volumes of the components at infinite dilution were calculated. The isobaric expansion and the isothermal compressibility were also driven from the Tait-type equation.