Abstract: A valve for inclusion or insertion in a tubular includes a substantially cylindrical outer valve housing; an inner sliding sleeve mounted axially movable inside the valve housing; and a seat arranged for receiving a drop ball, dart or falling device. The seat is built in such a way that it can partially or completely be removed or drilled out from the valve. The inner sliding sleeve includes a first profile arranged at a first end of the inner sliding sleeve and a second profile arranged at a second end of the inner sliding sleeve, wherein the first profile and the second profile are configured to be engaged with an activating or shifting tool inserted and run in the tubular after the seat has been partially or completely removed or drilled out from the valve in order to operate the valve from an open to a closed position and/or vice versa.

Abstract: The present invention provides a simple, robust, durable and reliable cylindrical valve, valve system and method for completion, stimulation and subsequent re-stimulation of well(s)for hydrocarbon production.