Jet pumping driven by light oil is one of the preferred lift methods for producing heavy oil in a deep heavy oil reservoir. Generally, the amount of light oil is too large to be accepted. One solution of reducing the amount of light oil is that partial produced fluid can be combined with the light oil at any reasonable ratio and then the produced fluid-light oil mixture is reinjected into the well as the power fluid. In this case, viscosity of the mixture keeps increasing and eventually reaches its equilibrium value, which is found to be a function of the reservoir oil viscosity, the light oil viscosity (VLO), the ratio of light oil (RLO) in the mixture (volumetric percentage) and the ratio of the well rate to the diluent rate (M ratio). Thus the optimal ratio of light oil in the mixture can be determined by using an iterative algorithm. All of the above-mentioned parameters result in a change of the viscosity of the produced fluid-light oil mixture and the pressure loss in the production string, especially the VLO and the RLO. A field application example shows that the amount of the light oil used can be reduced by more than 50%.
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