Abstract: The thermal-surfactant combined flooding is an effective EOR technique for heavy oil reservoirs， which
has been applied in several oilfields for pilot tests. A theoretical study on this technique is conducted by means
of analytical analysis and numerical simulation. A comparatively complete thermal-chemical flooding mathematic
model is built based on the dominant physical and chemical phenomena occurred during this combined flooding，
and a 3D three-phase simulator is developed correspondingly. To improve the economic benefits of such a combined
flooding， prediction models of different development stages are set up by means of injector-producer correlationship
analysis and numerical reservoir simulation. Then， the non-linear programming theory is employed to perform
integrated programming for heavy oil reservoirs in the situation where steam flooding is initially adopted and a
combined flooding is adopted at later stages. The self-adapting genetic algorithm is used for model solution， the
results of which indicate that a programmed combined flooding can lead to better economic benefits.