1. n. [Well Workover and Intervention]

A condition that may occur during ball diversion treatments in which all open perforations capable of receiving fluid are sealed. Ballout is signified by a rapid increase in treating pressure. Maintaining the treatment pressure may result in the breakdown and subsequent treatment of plugged perforations. If no further injection is possible, the pressure must be released to unseat the ball sealers, at which time the treatment will be terminated.