Circulating usage of partial produced fluid as power fluid for jet pump in deep heavy-oil production

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 required is too large to be acceptable. One solution which reduces the amount of light oil required is to blend light oil with a portion of the produced fluid at a reasonable ratio. Then, the produced fluid/light-oil mixture is reinjected into the well as the power fluid. In this case, the viscosity of the blended power fluid keeps increasing and eventually reaches its equilibrium value, which has been found to be a function of reservoir-oil viscosity, light-oil viscosity, the ratio of light oil to blended power fluid (volumetric percentage), and the ratio of well rate to diluent rate (M ratio). Moreover, an optimal ratio of light oil to blended power fluid can be determined by using an iterative algorithm developed in this study. Variations in any of the previously mentioned parameters, especially the viscosity of light oil and the ratio of light oil to blended power fluid, result in a significant change in both the viscosity of the blended power fluid and the pressure loss in the production string. It has been shown in a field application that the amount of light oil used for driving the jet pumping operation can be reduced by more than 50%.