Abstract: In an offshore oil installation, the closure device (40) of a subsurface test tree placed in the blowout preventer stack on the seabed is made in a modular manner. More precisely, the closure device comprises a plurality of lengths (54,56') suitable for being placed in arbitrary order between a top element (50) and a bottom element (52). This arrangement makes it possible to place the connector (46) between the total shutoff valves (26) and the partial shutoff valves (28) of the blowout preventer stack, and to place the valves (42,44) of the closure device (40) in a closure length (54) that is situated beneath the partial shutoff valves (28). The two total shutoff valves (26) can thus be actuated regardless of the type of blowout preventer stack that is used.

Abstract: A test string section for a well comprises a circulating valve (40) including a mandrel (60), a rupture disk (68), and a series of ports (56). The valve is arranged above a packer. A second port (50) is arranged on a pipe section (44) below the packer and a flow tube (52) extends through the internal bore (66). On rupturing the rupture disk, the port (56) is opened whereby mud can be pumped into a rathole via the port to kill the rathole while the seal of the packer against a wall of the wellbore is still intact and the packer remains in a set condition.