A method for drilling a wellbore, comprising: drilling the wellbore by injecting drilling fluid into a top of a tubular string disposed in the wellbore at a first flow rate and rotating a drill bit, wherein: the tubular string comprises: the drill bit disposed on a bottom thereof, tubular joints connected together, a longitudinal bore therethrough, and a port through a wall thereof; the drilling fluid exits the drill bit and carries cuttings from the drill bit; and the cuttings and drilling fluid flow to surface via an annulus defined between the tubular string and the wellbore; characterized in that the tubular string further comprises a sleeve in fluid communication with a hydraulic chamber and operable between an open position where the port is exposed to the bore and a closed position where a wall of the sleeve is disposed between the port and the bore; and in that the method further comprises: moving the sleeve to the open position by injecting hydraulic fluid into the hydraulic chamber; and injecting drilling fluid into the port at a second flow rate while adding a tubular joint or stand of joints to the tubular string, wherein injection of drilling fluid into the tubular string is continuously maintained between drilling and adding the joint or stand to the tubular string. drilling the wellbore by injecting drilling fluid into a top of a tubular string disposed in the wellbore at a first flow rate and rotating a drill bit, wherein: the tubular string comprises: the drill bit disposed on a bottom thereof, tubular joints connected together, a longitudinal bore therethrough, and a port through a wall thereof; the drilling fluid exits the drill bit and carries cuttings from the drill bit; and the cuttings and drilling fluid flow to surface via an annulus defined between the tubular string and the wellbore; the tubular string comprises: the drill bit disposed on a bottom thereof, tubular joints connected together, a longitudinal bore therethrough, and a port through a wall thereof; the drill bit disposed on a bottom thereof, tubular joints connected together, a longitudinal bore therethrough, and a port through a wall thereof; the drilling fluid exits the drill bit and carries cuttings from the drill bit; and the cuttings and drilling fluid flow to surface via an annulus defined between the tubular string and the wellbore; characterized in that the tubular string further comprises a sleeve in fluid communication with a hydraulic chamber and operable between an open position where the port is exposed to the bore and a closed position where a wall of the sleeve is disposed between the port and the bore; and in that the method further comprises: moving the sleeve to the open position by injecting hydraulic fluid into the hydraulic chamber; and injecting drilling fluid into the port at a second flow rate while adding a tubular joint or stand of joints to the tubular string, wherein injection of drilling fluid into the tubular string is continuously maintained between drilling and adding the joint or stand to the tubular string. moving the sleeve to the open position by injecting hydraulic fluid into the hydraulic chamber; and injecting drilling fluid into the port at a second flow rate while adding a tubular joint or stand of joints to the tubular string, wherein injection of drilling fluid into the tubular string is continuously maintained between drilling and adding the joint or stand to the tubular string.