Contingent continuous circulation drilling system

A top drive system, comprising:

• a flow sub, comprising:
• a tubular housing having:
• a longitudinal bore formed therethrough, a flow port formed through a wall thereof, an upper coupling, and a lower coupling for connection to a tubular;
• a bore valve operable between an open position and a closed position, wherein the bore valve allows free passage through the bore in the open position and isolates an upper portion of the bore from a lower portion of the bore in the closed position;
• and
• a valve member for selectively opening and closing the flow port;
• and
• a top drive comprising:
• a motor operable to rotate a quill;
• a swivel having an inlet for receiving a kelly hose and an outlet in fluid communication with the quill;
• and
• a backup wrench movable between an upper position and a lower position,
• wherein:
• the motor, swivel, and backup wrench are connected together to form a frame of the top drive,
• the upper coupling is connected to the quill,
• the backup wrench is engageable with an upper portion of the tubular housing in the upper position,
• the backup wrench is engageable with a threaded coupling of the tubular housing in the lower position,
• the valve member is a sleeve,
• the sleeve is disposed in the tubular housing,
• the sleeve is movable between an open position where the flow port is exposed to the bore and a closed position where a wall of the sleeve is disposed between the flow port and the bore, and
• the flow sub further comprises a bore valve actuator operably coupling the sleeve and the bore valve such that opening the sleeve closes the bore valve and closing the sleeve opens the bore valve.

A method for deploying a tubular string into a wellbore, comprising:

• injecting fluid through a top drive and a flow sub into a top of the tubular string and lowering the tubular string into the wellbore, wherein:
• the flow sub connects the tubular string top to a quill of the top drive,
• the flow sub is in a top injection mode, and
• the flow sub has:
• a port formed through a wall thereof,
• a valve member closing the port, and
• an open bore conducting the fluid from the quill into the tubular string top;
• halting lowering of the tubular string;
• and
• while lowering is halted, shifting the flow sub to a side injection mode, thereby moving the valve member to open the port and closing the bore, and injecting the fluid into an annulus of the wellbore, thereby circulating from the annulus, up a bore of the tubular string, and to the port.

A method for deploying a tubular string into a wellbore, comprising:

• injecting fluid into an annulus of the wellbore, thereby circulating from the annulus, up a bore of the tubular string, and to an open port of a flow sub connected to a top of the tubular string and lowering the tubular string into the wellbore,
• wherein:
• the tubular string has a bottomhole assembly,
• the bottomhole assembly includes a reverse circulation drill bit and a drilling motor, and
• the drilling motor utilizes the injected fluid to rotate the drill bit, thereby drilling the wellbore;
• halting injection of the fluid through the annulus and the tubular string and halting lowering of the tubular string;
• while lowering is halted:
• disconnecting the flow sub from the tubular string top;
• adding one or more tubular joints to the tubular string and connecting the flow sub to a top of the added joints;
• and
• resuming lowering of the tubular string.