Subsurface safety valve

Abstract

The invention discloses a subsurface safety valve. The subsurface safety valve comprises a body, wherein an upper joint, a middle joint, an outer cylinder and a lower joint are sequentially connected to form the body, a central pipe is arranged inside the body, at least one set of metal bellows assemblies is arranged inside the pipe wall of the middle joint, upper ends of metal bellows assemblies are communicated with an oil passage on the body, which is connected with an external oil pipe, lower ends of metal bellows assemblies are connected with a positioning ring, which is fixed on the peripheral wall of the central pipe, through a retractable gallows assembly, a boss is formed on the inner wall of the lower end of the outer cylinder, a pressure spring is sleeved on a portion of the central pipe, which is located between the positioning ring and the boss, and an elastic normally-closed valve plate which is axially matched with the central pipe is arranged at the lower end of the outer cylinder. The subsurface safety valve can be used in high-temperature, high-pressure and corrosive environments and in deep seas, rubber is not used, and the valve can meet high-pressure sealing requirements.

Description

technical field [0001] The invention belongs to oil and gas well exploitation equipment, in particular to an underground safety valve for oil and gas exploitation. Background technique [0002] In the oil extraction industry, when performing downhole operations, the flow rate of hydrocarbon fluids often increases but cannot be controlled due to failure of extraction equipment and other reasons. At this time, it is necessary to close the channel in time to ensure operation safety and avoid greater accidents. In actual production, there must be a device (downhole safety valve) to close the fluid channel and realize the blocking function. Downhole safety valve is a kind of downhole equipment to prevent blowout and ensure production safety. When an emergency occurs, the oil and gas well can be closed by releasing pressure from the control pipeline connected to the ground to close the valve plate. When it needs to be opened, the valve plate can be opened by adding hydraulic pres...

AI Technical Summary

Problems solved by technology

[0008] 1) At present, the downhole safety valves in the world either adopt a piston structure or a sliding mandrel structure to push the valve plate to open and close. Both structures must be sealed by seals, which will bring the following disadvantages: a) Cannot withstand high temperature of 350°C; b) Once the sand and dust in the well enter the sealing surface, it may cause jamming; c) Repeated opening and closing may cause damage to the seal, so the number of uses is limited

[0009] 2) Due to the limited spring force of the traditional downhole safety valve, the cross-sectional area of ​​the piston is required not to be too small due to the stability of the rod, so that the opening and closing pressure cannot be too high, so it is difficult to meet the requirements of ultra-deep installation.

This construction does not get rid of the reliance on tape, the temperature will make the seal fail, and the 10000psi high pressure seal of the NPT thread is not good

[0011] 4) The static sealing problem of the body of the downhole safety valve at high temperature

[0012] 5) The compressive strength of the control pipeline and the body under high pressure

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