A formation-fracking system has an gas/fluid accumulator, one or more pumps for pumping a fracking fluid, a fracking string extending to a subterranean formation and defining a fracking channel and a circulation channel, a valve subsystem coupling the pumps to the gas/fluid accumulator and the fracking string, and a bypass valve in fluid communication with the fracking channel and a fracking section. The valve subsystem alternately transitions between a first state for directing fracking fluid from the pumps and the gas/fluid accumulator to the fracking channel to create a kinetic-energy surge, and a second state for directing fracking fluid from the pumps to the gas/fluid accumulator for storing energy therein and for fracturing the formation using the kinetic-energy surge. The bypass valve enables a bypass channel fluidly connecting the fracking channel to the circulation channel in the first state and abruptly disables the bypass channel in the second state.