IMPROVED PUMP FOR LIFTING FLUID FROM A WELLBORE
The invention relates to a pump for lifting fluid from a wellbore. The pump comprises a first piston and a second piston, each piston being configured for linear reciprocal movement generated by magnetic fields. A control system is operable to control the magnetic fields to generate substantially concurrent opposed movement of the first and second pistons so as to provide a substantially continuous flow of fluid from the wellbore. The control system may comprise one or two power cables connected to Variable Speed Drives (VSDs).