A pump system for multi-phase fluids that includes a drive-shaft (11),
mechanical differential units (12, 22, 23, 23', D.sub.1 . . . D.sub.n) and
pumps (14, 14', 25, 25', 25", 25'", B.sub.1 . . . B.sub.n) where the
differential units allow for the changing of pump rotation speeds between
pumps(14, 14', 25, 25', 25", 25'", B.sub.1 . . . B.sub.n) so as to adjust
the compressibility of fluids in order to reduce or eliminate circulatory
flow. There is also a description of the method of operating the system
according to the invention.
