NOVELTY - The apparatus has a liquid buffer isolating a discharge column (25) through which pumped geothermal fluid including non-condensable gases (NCG), flows from a lubrication column (2) through which lubrication oil for lubricating bearings of line shaft flows. The buffer is interposed between the discharge column and an outlet of the lubrication column to prevent infiltration of the NCG into the lubrication column. The buffer is rotatable together with a line shaft (5) and defined by a cup structure, which comprises an upper oil receiving section.    USE - Apparatus for maintaining operation of a geothermal production pump e.g. vertical turbine pump and downhole pump, that is utilized for extracting geothermal fluid from a deep production well.    ADVANTAGE - The apparatus maintains operation of a geothermal production pump when extracting geothermal fluid comprising high NCG content. The pump can exit lubricating oil to a bottom part of the lubrication column through channels to bypass ports, thus allowing oil to be discharged into an annulus of a production well casing. The apparatus flows filtrated NCG upwardly within the lubrication column to avoid sluggish and non-uniform oil flow to improve lubricating capability and prevents infiltration of the NCG to the lubrication column by providing the cup structure attached to the line shaft. The apparatus increases momentum of fluid to be extracted from a well in the pump during rotation of impellers and reduces overfow oil from the cup structure by small clearance between a throttle bearing and the line shaft such that flow rate of overflowing oil entrained in the pumped geothermal fluid is reduced.    DETAILED DESCRIPTION - The bearings are throttle bearings. The oil receiving section is a cylindrical wall. An INDEPENDENT CLAIM is also included for a geothermal production pump.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a portion of a production well and a pump.    Lubrication column (2)    Discharge pipe (3)    Motor (4)    Line shaft (5)    Discharge column (25)