A computer-implemented method for performing a wellbore or survey operation at an oilfield comprising one or more wellsites based on basin modelling of the basin in which the one or more wellsites are located, the method comprising: receiving measurements related to the oilfield to generate a plurality of data items of a volume dataset; obtaining, for each of a plurality of cells in the data volume, a permeability measure to represent fluid passing ability in a corresponding location in the oil field; generating a plurality of neighboring cell combinations based on each of the plurality of neighboring cell combinations comprising a connected portion of the plurality of cells, and the permeability measure for each cell of the plurality of cells in the connected portion satisfying a pre-determined threshold; selecting (204, 205), from the plurality of neighboring cell combinations and based at least on the permeability measure, a selected neighboring cell combination having an optimal combined free advection measure, representing an amount of free advection in an oilfield location corresponding to the neighboring cell combination having an effective Rayleigh number with the highest value and wherein a local region in the oilfield that corresponds to the selected neighboring cell combination is identified as an advection candidate region of the oilfield; generating an equivalent thermal conductivity for the advection candidate region by multiplying an effective thermal conductivity associated with the selected neighboring cell combination by a multiplier factor, wherein the multiplier factor comprises a ratio between the optimal combined free advection measure and a pre-determined free advection measure baseline; performing, based at least on the equivalent thermal conductivity, a basin modeling of the oilfield to generate a modeling result; generating a control signal based on the modeling result; and performing the wellbore or survey operation based on the control signal. receiving measurements related to the oilfield to generate a plurality of data items of a volume dataset; obtaining, for each of a plurality of cells in the data volume, a permeability measure to represent fluid passing ability in a corresponding location in the oil field; generating a plurality of neighboring cell combinations based on each of the plurality of neighboring cell combinations comprising a connected portion of the plurality of cells, and the permeability measure for each cell of the plurality of cells in the connected portion satisfying a pre-determined threshold; selecting (204, 205), from the plurality of neighboring cell combinations and based at least on the permeability measure, a selected neighboring cell combination having an optimal combined free advection measure, representing an amount of free advection in an oilfield location corresponding to the neighboring cell combination having an effective Rayleigh number with the highest value and wherein a local region in the oilfield that corresponds to the selected neighboring cell combination is identified as an advection candidate region of the oilfield; generating an equivalent thermal conductivity for the advection candidate region by multiplying an effective thermal conductivity associated with the selected neighboring cell combination by a multiplier factor, wherein the multiplier factor comprises a ratio between the optimal combined free advection measure and a pre-determined free advection measure baseline; performing, based at least on the equivalent thermal conductivity, a basin modeling of the oilfield to generate a modeling result; generating a control signal based on the modeling result; and performing the wellbore or survey operation based on the control signal.