UNDERBALANCED DOWNHOLE CASING VALVE AND FORCE OPEN TOOL THEREOF

摘要

The present invention relates to an underbalanced downhole casing valve controlled hydraulically, wherein: a first hydraulic fluid chamber (11) formed between bosses in the inner chamber of an upper fitting and on the outer surface of an inner cylinder and on the inner surface of an upper outer cylinder; a second hydraulic fluid chamber (12) formed between the lower portion of the boss of the inner cylinder and an inner chamber of the upper outer cylinder; Axial bores are disposed on the upper end of the upper outer cylinder, two of them are respectively fluidly communicated with the first hydraulic fluid chamber (11) and the second hydraulic fluid chamber (12); a second annulus formed between the lower portion of the upper outer cylinder and the inner cylinder, which is communicated with the bore disposed in the upper outer cylinder and is communicated with a third annulus defined by the upper outer cylinder and the valve assembly. If one person wants to open/close the casing valve, he/she only pumps using one/the other pipe. When the casing valve is closed, the downhole pressure can be measured. When the underbalanced downhole casing valve is closed and can not be opened by the hydraulic pressure on the ground, the underbalanced downhole casing valve can be opened and locked in a permanent open state by the matched force open tool.