The thermal conductivity of five samples of crude oil and one sample of gas condensate was measured by the transient hot-wire technique. The measurements were made along isotherms (245, 250, 273, 295, 320, 336, and 373 K) in the pressure range from atmospheric pressure up to 1000 MPa and along isobars (at 0.1, 100, 200, 300, 400, 500, and 1000 MPa) in the temperature range 245–450 K. It was observed that the thermal conductivity of the samples investigated strongly depends on the pressure and rises with increasing pressure for all the temperatures. At a certain pressure, the temperature coefficient of thermal conductivity reverses from negative to positive. The pressure at which this reversal was observed varied in the range of 300–380 MPa.
