FIELD: oil and gas industry.
SUBSTANCE: control system of well safety cutoff valve controls the operation of cutoff valve in case of its normal functioning in open and closed positions, as well as in case of its operation in "protection against failures" mode at malfunction of key component of the system. Peculiar feature of the system is available control line from the surface, which is separated at well safety cutoff valve and passes to one end of two separate piston chambers (64, 46) which in their turn are located on one line and are isolated from pipe string pressure. Piston (36) in one chamber is larger than the other one; at that, pistons (36, 52) are connected together in order to perform joint movement. Each side of piston of non-balanced system has seal (38, 54) fixed on it, and the other side has rod (40, 56) attached to it, which goes out of the chamber. Bypass pipeline (68) connects chambers (48, 62) at the point between seals in each chamber and has large reservoir (70). Bypass pipeline (68) is filled with compressed fluid medium. Fail-safe closing of the valve occurs in case of depressurisation of any of four seals.
EFFECT: improving reliability of control systems of well instruments.
29 cl, 1 dwg
