Abstract: A method and apparatus for exploiting oilfields involving the installation of a well network in the form of an open or non-open ring that is generally non-circular. Horizontal well sections (3) are drilled from vertical injection (1) or producing (2) wells that already exist, to interlink them. The vertical wells that are located in the same line are used as injection wells, thereby promoting oil sweeping in the reservoir (R) towards the ring-shaped producing wells (P1) or (P2). In another embodiment, vertical service wells are drilled for monitoring the characteristics of the reservoir (R). From these wells, horizontal wells are drilled in a ring-shaped form to obtain concentric well rings from the periphery to the central region of the reservoir (R). The outermost horizontal well is used as injection well and the innermost annular horizontal wells are used as producing wells.

Abstract: A description is given of a system for exploiting oilfields, be these either already developed or to be developed.

Abstract: A pressure valve assembly for use in gas-lift producing oil-wells includes a cylindrical body, a first pressure chamber including bellows located in the body, a second pressure chamber in the body having a first port for communication with gas pressure in a lining or casing, a second port for communicating the second chamber with a pipe in the lining, a valve stem connected to the bellows for movement in the second chamber and a gate valve assembly connected to the stem in the second chamber for controlling the gas flow between the first and second ports.