US Patent 7866402 Circulation control valve and associated method

A circulation control valve. A method of controlling circulation flow between an interior flow passage of a tubular string and an annulus external to the tubular string in a subterranean well includes the steps of: interconnecting a valve in the tubular string, the valve including at least one opening for providing fluid communication between the interior flow passage and the annulus; applying an increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is prevented, thereby permitting fluid communication through the opening between the interior flow passage and the annulus; and then applying another increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is permitted, thereby preventing fluid communication through the opening between the interior flow passage and the annulus.