Patent ID: 7866402

Claim:
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, the method comprising the steps of: interconnecting a valve in the tubular string, the valve including at least one opening; applying a first increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is prevented and while the interior flow passage through the valve is unobstructed, thereby permitting fluid communication through the opening between the interior flow passage and the annulus prior to release of the first increased pressure; and then applying a second increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is permitted and while the interior flow passage through the valve remains unobstructed, thereby preventing fluid communication through the opening between the interior flow passage and the annulus.