Patent ID: 8256515

Claim:
A dart and plug dropping head for use in sequentially dropping one or more balls and plugs into a well casing, comprising: a) a housing having an inlet at its upper end adapted to be fluidly connected in line with the lower end of a top drive, an outlet generally aligned with the inlet; b) a main flow channel that connects the inlet and the outlet; c) a plurality of valving members spaced between the inlet and the outlet, each valving member having a flow bore, and being movable between open and closed positions; d) one or more fluid flow channels that enable fluid to bypass the valving members when a valving member is in the closed position; e) at least one of the valving members having a cross section that, in the closed position, does not valve fluid flow in the main flow channel; f) wherein fluid flow in the main channel flows around the valving member when it is in the closed position and through the valving member when it is in the open position; g) a sliding sleeve above each valving member that is configured to support a ball or plug when the valve below the sleeve is closed; h) a plurality of darts in the housing, each dart being of a first diameter and positioned above a valving member, wherein in the open position each valve flow bore is of a diameter that permits a dart to pass therethrough, and circulating fluid to pass downwardly therethrough when neither a ball nor plug is in the valve flow bore; i) a connector that connects to the housing to the well casing; and j) a pair of casing plugs that are contained in the casing below the connector, wherein each casing plug has a central longitudinal bore that is of a diameter greater than the said first diameter and is receptive of and interlocks with a dart that is dropped from the housing.