Abstract: This invention relates generally to petroleum well treatment and more particularly to improvement of production from earthen petroleum reservoirs of low permeability by fracturing the petroleum bearing strata. The present invention accomplishes this purpose by use of energy capsules that upon implosion produce acoustic waves as to cause the formation to undergo periodic stress beyond its elastic endurance limit and to fail by elastic fatigue.A plurality of energy capsules designed to implode at different hydrostatic pressures in order to release shock waves to produce a cavitational action in the areas adjacent to the well bore are transmitted in a fluid medium. The energy capsules may be utilized in conjunction with pressurized fluid that is oscillated such that the combined elements of a pressurized fluid system and the release of shock waves at spaced time intervals from the energy capsules is obtained.