Abstract: A surface power unit for use on a subterranean well generates a series of pulses of pressurized fluid to a downhole pump. A sequencing mechanism connects and disconnects the surface power unit to each of a plurality of downhole pumps in a predetermined order such that a pulse of pressurized fluid is being applied to one or more of the plurality of downhole pumps during a power cycle while each of the other ones of the plurality of downhole pumps is completing its pumping cycle. The number of downhole pumps which can be operated from a single surface power unit is limited by the ratio of the length of the power cycle to the length of the pumping cycle of the downhole pumps. The sequencing means can include a clocking device such as a shift register which generates a sequence of enabling signals to corresponding signal amplifiers for each well.