Drill string diverter apparatus and method

The present invention relates to a drill string diverter apparatus for reducing surge pressure when lowering a liner into a partially cased wellbore. The diverter apparatus is connected in a pipe string above a liner being lowered into a wellbore. The diverter apparatus comprises a tubular housing with ports defined therethrough to communicate and redirect fluids received in the liner to the annulus between the diverter apparatus and casing previously set in the wellbore. The diverter apparatus has an open position whereby the ports are open and communication is established and a closed position whereby flow through the ports is prevented. A sliding sleeve is disposed about an outer surface of the tubular housing and engages the casing. The sleeve moves vertically relative to the tubular housing once the diverter apparatus has been lowered into the casing to selectively open and close the flow ports. A J-slot means is provided for locking the diverter apparatus in its closed position. The diverter apparatus includes upper and lower locking elements which will engage the J-slot when the diverter apparatus is moved to its closed position to prevent relative movement between the sleeve and the tubular housing.