Method for enhancing recovery of heavy crude oil by in-situ combustion in the presence of strong aquifers

A method for enhancing recovery of crude oil from a crude oil containing formation (1), which is located adjacent to a strong aquifer (2) comprises: - producing crude oil through at least one crude oil production well (5) having an inflow zone which traverses the crude oil containing formation (1) and in which zone a fluid pressure (or bottomhole pressure or BHP) is lower than a fluid pressure in the aquifer (2); - injecting an oxidant into the crude oil containing formation through one or more oxidant injection wells (3,4) and igniting a mixture of oxidant and crude oil to heat the hydrocarbon containing formation (1) such that the viscosity of at least a substantial fraction of unburned crude oil in the crude oil containing formation (1) is reduced to such a level, preferably to less than 50 cP, that influx of water from the aquifer (2) into the inflow zone of the crude oil production well (5) is reduced; and - allowing the aquifer (2) to sweep the oil into the inflow zone of the production well (5) after oxidant injection has ceased, the viscosity if the produced crude oil being substantially reduced by heating of the reservoir (1).