Tool Introduction

The full bore LPR-N test valve is a downhole test switch valve used in casing wells with large bore and annular pressure operation. This type of test valve does not require the operation of the tubing string and has the ability to obtain multiple well opening and closing when a full bore test tubing string is required.

Structural characteristics

① The pressure control test valve consists of four basic parts: ball valve part, power part, nitrogen power mechanism, and metering part;

② Equipped with a dedicated measuring set to ensure reliable opening and closing of the ball valve;

③ The pressure during acidification and fracturing does not affect the position of the ball valve;

④ Apply shear pins to keep the ball valve closed when going down the well, so the initial opening of the ball valve is completed instantly;

⑤ Circulation and acidification can be carried out by testing the valve when the packer is not unsealed;

⑥ Use higher operating pressure as much as possible to achieve maximum shut in force.

operation

When testing the valve in the well, the annular pressure enters the annular hole below the oil chamber, causing the dedicated hydraulic oil above and below the measuring sleeve to be pressurized. Before testing, several shear pins are used to ensure that the ball valve is in the closed (or open) state, because due to the action of the measuring sleeve, when the tool reaches the predetermined testing depth, the pressure in the nitrogen chamber is slightly lower than the annular pressure, which creates a pressure difference above and below the piston that causes the ball valve to open. Therefore, the use of shear pins is necessary. When the packer is seated and pump pressure is applied to the annulus, the ball valve can only be opened when the pressure difference acting on the piston in the up and down directions reaches enough to shear off the shear pin. When the static column pressure exceeds approximately 2.75MPa (400Psi), the ball valve will fully open; However, it is necessary to increase the annular pressure to the final opening pressure value and stabilize it for 5 minutes less in order to compress the nitrogen gas in the nitrogen chamber, so that the ball valve can reach the fully open position. After the pressure is measured by the measuring sleeve, the pressure in the nitrogen chamber will be slightly lower than the annular pressure, keeping the ball valve in the open position. Pay attention to the maximum safe value of the applied operating pressure. The ball valve closes by quickly releasing the pressure applied to the annulus. After closing the tool, it takes at least 5 minutes for the additional pressure stored in the nitrogen chamber to be released through the measuring sleeve.

technical parameter