Annular safety assembly for an oil well, especially a double production zone well

An annular safety assembly comprising a lower cylindrical body (7) and an upper cylindrical body (8) which are spaced apart and permanently held in a fixed position relative to each other by at least one connecting tube (2,3) for providing a connection between two aligned sections of production tubing situated one or each side of the said assembly and, from the top downwards between the two cylindrical bodies, a packer (13) arranged transversely around said connecting tube and capable of being applied, by transverse extension resulting from a lengthwise compression, against a casing into which the production tube is to be introduced lengthwise, a radial spacing ring (14) having a conical outer surface sloping inwards from top to bottom, a resilient anchorage ring (15) split along a generatrix, provided with anchorage teeth at its outer periphery and having a conical inner surface with the same slope as the slope of the conical outer surface of said spacing ring and applied at least partly thereagainst, and a thrust ring (16), and in said lower cylindrical body, a system of rams with upwardly projecting thruster-plungers (20,21) and adapted to be activated by the introduction of a fluid under pressure into said rams for displacing said thrust ring upwards, said anchorage ring being adapted, in a first step, to be applied against the casing by an upward displacement thereof relative to said spacing ring under the action of said thrust ring, itself displaced by said thruster-plungers and, in a second step, while said anchorage ring is held lengthwise against the casing to penetrate the casing transversely with said teeth under effect of a descending displacement of said spacing ring relative to said anchorage ring caused by the application of the weight of said assembly and said aligned sections of production tubing and permitting other lengthwise compression of said packer between said immobilized spacing ring and said upper cylindrical body, said anchorage ring and thrust ring forming a compact anchorage system and a channel (42) disposed parallel to and separate from said at least one connecting tube and extending through said lower cylindrical body (7) and said upper cylindrical body (8) and a safety valve secured to the lower end of said lower cylindrical body in alignment with said passage, said safety valve allowing to precluding passage of fluid through said passage from one lengthwise side to the other lengthwise side of said packer.