Control of annulus return flow in well operations

A method of controlling annulus flow in a subterranean well operation, the method comprising:

• connecting an annulus flow control tool in a tubular string, the annulus flow control tool including a bypass flow path and at least one external annular seal;
• deploying the tubular string into the well;
• sealingly engaging a well surface with the at least one external annular seal;
• flowing a first fluid through the tubular string into the well, thereby causing a second fluid in an annulus between the tubular string and the well surface to flow through the bypass flow path;
• rotating the tubular string, thereby disconnecting the at least one external annular seal from an inner mandrel of the annulus flow control tool;
• and
• closing the bypass flow path, the annulus flow control tool thereby blocking flow through the annulus.

A system for use with a subterranean well, the system comprising:

• a tubular string deployed into the well, an annulus being formed between the tubular string and a well surface surrounding the tubular string;
• and
• an annulus flow control tool connected in the tubular string, the annulus flow control tool including a bypass flow path, and at least one external annular seal configured to sealingly engage the well surface,
• in a bypass open position of the at least one external annular seal, fluid communication through the bypass flow path between opposite sides of the at least one external annular seal is permitted, and
• in a bypass closed position of the at least one external annular seal, fluid communication through the bypass flow path between the opposite sides of the at least one external annular seal is blocked, in which the at least one external annular seal is adapted to displace between the bypass open position and the bypass closed position in response to a pressure differential across the at least one external annular seal.