A casing perforating system (150) comprises a length of tubing (162) for mounting on a tubular string (152), the tubing (162) having a wall defining a throughbore for fluid communication with the string bore. Perforating charges are mounted to the tubing, for perforating bore liner. Seals (166; 168) are mounted on the tubing (162) for providing a seal between the tubing and liner, and may be used to isolate perforated zones.
