Internal Pressure Operated Circulating Valve
Full-bore circulating valve opened by internal differential pressure
Description
A full-bore circulating valve operated by internal differential pressure, for cased-hole and open-hole testing. After testing and before tripping out, internal differential pressure is applied to open the circulating port. During tripping out, it provides a flow passage for the string and serves as a backup circulating valve.
Features
- Consists of an upper adapter, operating mandrel, lower adapter, shear pins, lock ring and other parts
- While tripping in, the inner and outer pressures on the operating mandrel are balanced and the shear pins keep the circulating port closed
Operation
After the packer is set, the force produced on the operating mandrel by the internal-external pressure differential must not exceed the installed shear pin value, otherwise the circulating port will open early.
To operate, pressure up the string to the shear pin value to shear the pins. The operating mandrel moves downward to open the circulating port, and the lock ring locks the mandrel in the open position permanently.
