Latch Mandrel

I. Core Function of Latch Mandrel

1. Controlling Shock Start and Stop:

This is its core function. When the drill string is pulled up, the slips and other components grip the slip mandrel under the elastic force of the disc spring, delaying the energy storage of the shock absorber. When the tension overcomes the locking force, the slip mandrel releases its constraint, and the elastic potential energy of the drill string is released instantaneously, generating the upward impact force. The same principle applies during downward impact; as the drill string is lowered until the pressure reaches the downward locking force, the locking mechanism of the mandrel unlocks, triggering the downward impact action.

2. Prevention of accidental shocks: 

In conventional drilling operations such as drilling, tripping, and connecting single sections, the unlocking force of the corresponding locking mechanism is set to be greater than the drill string tension in these conventional operations. This ensures that the hydraulic damping mechanism of the shock absorber remains inactive, fundamentally preventing accidental shocks from interfering with the drill string and the drilling process.

II. Applications and Material Requirements of Latch Mandrel

1. Application Scenarios:

Primarily used in complex conditions such as directional wells and underbalanced drilling in oil and gas drilling. Compatible with various mechanical hydraulic shock absorbers, including the JYQ type, to handle downhole stuck pipe accidents and ensure continuous drilling operations.

2. Materials and Processing: 

Due to the need to withstand frequent locking impacts, drilling fluid corrosion, and the high-pressure, high-temperature environment downhole, high-strength alloy steel is typically used. Simultaneously, its surface requires precision machining to ensure accurate fit with components such as slips and slip sleeves. Some models also undergo wear-resistant and corrosion-resistant treatments to extend their downhole service life.