Continuous mixing device, method and use in an installation for pumping a high viscosity fluid

An installation for pumping a high viscosity crude oil in a wall incorporating a casing, wherein said installation comprises a continuous mixing device comprising a body in which fluids flow between an inlet and an outlet of said body and at least two fluids with different viscosities enter through said inlet, a rotating shaft having at least two blades and being suitable for supplying at the outlet from said body, a mixture of said two fluids, said mixture having viscosity less than that of the most viscous fluid entering said inlet;

• and a hydraulic pump connected to said body via said outlet and wherein said installation has a pipe for feeding the crude oil to the inlet of said mixing device, a pipe connecting the outlet from said mixing device to an inlet of the pump, a hydraulic motor for rotating the pump and the rotating shaft of said mixing device, a pipe for injecting driving fluid connecting an injection installation on the surface to the motor, an outlet pipe from the pump conveying the mixture to the surface again and an outlet pipe from the motor conveying some of the driving fluid to the surface again, the remainder being conveyed to the inlet of said mixing device through another pipe.