A well jetting apparatus for use in fracturing of a well. Fracture initiation is provided by forming openings through the well casing and then forming fan-shaped slots in the formation surrounding the casing. Those slots are formed by a the jetting apparatus which has at least one hydraulic jet directed through the opening. The apparatus may be pivoted generally about the point of the opening to form the slots, but preferrably a plurality of slots are formed substantially simultaneously. These fan-shaped slots circumscribe an angle about the axis of the casing substantially greater than the angle circumscribed by the opening itself through which the slot was formed. These techniques are particularly applicable to fracturing of horizontal wells, but the apparatus may be used in any well configuration.