Oil Well Downhole Testing Tubing String Tester Valve Flapper TST Valve

The TST valve is the tubing string tester valve as the part of the DST Toolstring during the well pressure-test the workstring while running in the hole. The tubing string tester is featured with full bore design and requires a differential pressure between the annulus and the tubing to shear. The tubing string tester valve is applied in cased hole drill stem testing operation and oil well flow operations. The tester valve is composed with flapper valve and spring, locking dogs and Shear pin section

How to operate the TST Valve

When the TST flapper valve opens, it allows the workstring to fill up. The shear pins hold the mandrel in place. The workstring can be pressure-tested as many times as required as it is run in the hole. While the workstring is stationary, a spring keeps the flapper valve closed. After the workstring pressure test is complete, the tool is sheared when annulus pressure is applied to the predetermined shear pin rating. (The shear rating can be adjusted in 500 psi increments to shear from 500 to 60000psi differential). When the pins shear, the mandrel moves up and pushes the flapper open, allowing the locking dogs to engage. The tool is then fully open. The tool works on differential pressure between annulus and tubing. Failure to shear initially on application of annulus pressure is not critical.

Specification of Tubing String Tester Valve

﹡HSE﹡Safety instructions of the Tubing String Tester Valve

* When running each pressure test, you must increase pressure gradually. When the pressure is up to 20MPa, hold on for one minute, then every 10MPa keep it for one minute until the rating pressure;

* During doing the pressure test, the tool should be placed in the test pit and cover the protecting board on the pressure test plug.

* During the whole process, make sure the entire test operator keep away from plug and joint which may laps

* Test area should set isolation, others except operator not allowed to enter test area.

       * If there is anybody in the test area, it should set isolation, avoiding test production fly off the test area.

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