Circulating valve apparatus and drill stem test method allowing selective fluid communication between an above packer annulus and a rathole

摘要

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.