Process for pumping a gas/liquid mixture in an oil extraction well and device for implementing the process

An apparatus for pumping a two-phase gas/liquid mixture in an extraction well whose initial gas percentage is greater than approximately 40% by volume, comprising:

• a first centrifugal separating module having a cylindrical casing providing for axial flow of the gas/liquid mixture and means for discharging the separating gases outside the casing;
• a cooling module comprising an outer casing connected in a sealing manner to the casing of the first separating module and, within said outer casing, a second coaxial cylindrical casing containing a motor which is surrounded on either side, in the longitudinal direction, by means for maintaining a seal towards the upstream and downstream sides at the level of the drive spindles of the motor;
• means for diverting the axial flow of the gas/liquid mixture outside the second casing at the entry of the cooling module;
• and
• means at the exit of the cooling module for bringing the flow along the axis of a centrifugal pumping module connected to a pipe string for discharging the fluid, the pumping module and separator being driven by the motor.