Autonomous units and methods for downhole, multi-zone perforation and fracture stimulation for hydrocarbon production. The autonomous unit may be a perforating gun assembly, a bridge plug assembly, or fracturing plug assembly. The autonomous units are dimensioned and arranged to be deployed within a wellbore without an electric wireline. The autonomous units may be fabricated from a friable material so as to self-destruct upon receiving a signal. The autonomous units include a position locator for sensing the presence of objects along the wellbore and generating depth signals in response. The autonomous units also include an on-board controller for processing the depth signals and for activating an actuatable tool at a zone of interest.