A method of completing a well, comprising: forming a wellbore, the wellbore comprising a bore extending into a subsurface formation; lining at least a lower portion of the wellbore with a string of production casing; placing a valve along the production casing, the valve creating a removable barrier to fluid flow within the bore; perforating the production casing along a first zone of interest within the subsurface formation, the first zone of interest residing at or above the valve, wherein perforating the production casing comprises; pumping an autonomous perforating gun assembly into the wellbore, the autonomous perforating gun comprising; a perforating gun; a depth sensor for sensing the location of the perforating gun within the wellbore based on the spacing of casing collars along the wellbore; and an on-board controller configured to send an actuation signal to the perforating gun to cause one or more detonators to fire when the locator has recognized a selected location of the perforating gun along the wellbore; and autonomously firing the perforating gun along the first zone of interest; injecting a slurry into the wellbore, the slurry comprising a fracturing proppant; in response to a condition of screen-out along the first zone of interest during the injecting, pumping the slurry at a pressure sufficient to move the valve and overcome the barrier to fluid flow, thereby exposing ports along the production casing to the subsurface formation at or below the valve; and further pumping the slurry through the exposed ports, thereby remediating the condition of screen-out. forming a wellbore, the wellbore comprising a bore extending into a subsurface formation; lining at least a lower portion of the wellbore with a string of production casing; placing a valve along the production casing, the valve creating a removable barrier to fluid flow within the bore; perforating the production casing along a first zone of interest within the subsurface formation, the first zone of interest residing at or above the valve, wherein perforating the production casing comprises; pumping an autonomous perforating gun assembly into the wellbore, the autonomous perforating gun comprising; a perforating gun; a depth sensor for sensing the location of the perforating gun within the wellbore based on the spacing of casing collars along the wellbore; and an on-board controller configured to send an actuation signal to the perforating gun to cause one or more detonators to fire when the locator has recognized a selected location of the perforating gun along the wellbore; and autonomously firing the perforating gun along the first zone of interest; pumping an autonomous perforating gun assembly into the wellbore, the autonomous perforating gun comprising; a perforating gun; a depth sensor for sensing the location of the perforating gun within the wellbore based on the spacing of casing collars along the wellbore; and an on-board controller configured to send an actuation signal to the perforating gun to cause one or more detonators to fire when the locator has recognized a selected location of the perforating gun along the wellbore; and autonomously firing the perforating gun along the first zone of interest; injecting a slurry into the wellbore, the slurry comprising a fracturing proppant; in response to a condition of screen-out along the first zone of interest during the injecting, pumping the slurry at a pressure sufficient to move the valve and overcome the barrier to fluid flow, thereby exposing ports along the production casing to the subsurface formation at or below the valve; and further pumping the slurry through the exposed ports, thereby remediating the condition of screen-out.