Drilling jar
发布时间：2015-01-08 13:14    浏览量：1617

Description:

The Downhole Hydraulic/Mechanical Drilling Jar(HMJ) is a double action Jar , designed to deliver hydraulic delay when jarring in the up direction, and mechanical release when jarring in the down direction. The HMJ incorporates a latch mechanism to keep the jar locked in the neutral position and eliminate un expected jarring while tripping or racking back in the derrick.

Features/benefits:

（1）The HMJ is normally operated in the latched position to reduce unexpected jarring while drilling, and eliminate movement between jar components to increase service life.

（2）The HMJ operates with a simple up and down motion and is not affected by torque.

（3）The spline drive and latch mechanism are enclosed in a single ,sealed oil chamber without ports that might fill with cuttings and restrict the down jar stroke.

（4）The hydraulic delay mechanism is located in a separate chamber to prevent contamination and increase reliability.

（5）With the latch mechanism in the cocked or latch position, the inner mandrel and outer housing act integrally, virtually eliminating seal and inner tool wear during normal drilling conditions. This is no need to extend or open the jar before running in the hole.

（6）Standard seals in the tool are effective to 275F (135C). The jar can be dressed with seals effective to 450F(230C) for hot hole environments. External sealing surface are tungsten carbide-coated to enhance wear and corrosion resistance.

（7）The HMJ can be run in tension or in compression within the preset latch settings

Operation：

Jarring up：

Jarring up is achieved by applying sufficient over pull to overcome the latch setting, which initiates the hydraulic time delay. During the time delay, the over pull at surface can be adjusted to vary the impact force.

After impact, apply a down force sufficient to close jar and re-engage latch, then repeat the jarring cycle as required.

Jarring down：

Jarring down is achieved by applying sufficient downward force to overcome the latch setting and pump open force. At that point, the HMJ will release and jar downward.

After impact, pick up the work string to re-engage the mechanical latch then repeat the jarring cycle as required.