Project Description
Double Acting Hydraulic/Mechanical Drilling Jar
The Wenzel Downhole Tools Hydraulic – Mechanical Double Acting Drilling Jar (HMDA) is a double acting jar, designed to deliver hydraulic delay when jarring up or down, complete with a mechanical lock in each direction. The HMDA incorporates a latch mechanism to keep the jar locked in the neutral position and eliminate unexpected jarring while tripping or racking back on the derrick.
- The HMDA is normally operated in the latched position to reduce unexpected jarring while drilling and eliminate movement between jar components, increasing service life.
- The HMDA operates with a simple up and down motion and is not affected by torque.
- The spline drive and latch mechanism are enclosed in a single, sealed oil chamber without ports to the annulus. Such ports on other jars may fill with cuttings and restrict the down jar stroke.
- The hydraulic delay mechanism is located in a separate chamber to prevent contamination and increase reliability.
- Impact force is controlled by the metering device that ensures consistent delay times over the full range of operating temperatures.
- With the latch mechanism in the latched position, the inner mandrel and outer housing act integrally, virtually eliminating seal and inner tool wear during normal drilling conditions. There is no need to extend or open the jar before running in the hole.
- Standard seals in the tool are effective to 250°F (120°C). The jar can be dressed with seals
effective to 400°F (200°C) for hot hole environments, and 450°F (230°C) for extreme
temperature environments. External sealing surfaces are tungsten carbide-coated to enhance
wear and corrosion resistance. - The HMDA can be run in tension or in compression within the preset latch settings.
Jarring Up
- Jarring up is achieved by applying sufficient overpull to overcome the latch setting, which initiates the hydraulic time delay. During the time delay, the overpull at surface can be adjusted to vary the impact force. See the table for the maximum load during delay.
- 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. During the time delay, the load at the surface can be adjusted to vary the impact force. See the table for the maximum load during delay.
- After impact, pull up with enough force to re-engage the mechanical latch then repeat the jarring cycle as required.
| Nominal OD (inch) |
Length (ft) |
Thru Bore (inch) |
Tensile Yield (lbs) |
Torsional Limit (ft lbs) |
Nominal Up Latch Setting (lbs) |
Nominal Down Latch Setting (lbs) |
Max Pull During Delay (lbs) |
Free Stroke Up/Down (inches) | Total Stroke (inches) |
|---|---|---|---|---|---|---|---|---|---|
| 4.75 | 21.5 | 2.25 | 370 600 | 21 500 | 55 000 | 30 000 | 85 000 | 8.0 | 25.0 |
| 6.50 | 23.0 | 2.75 | 1 220 000 | 63 700 | 90 000 | 40 000 | 175 000 | 8.0 | 25.0 |
| 8.00 | 23.2 | 2.81 | 1 293 900 | 133 500 | 100 000 | 45 000 | 300 000 | 8.0 | 25.0 |
| 9.50 | 24.5 | 3.00 | 2 106 900 | 189 300 | 110 000 | 50 000 | 350 000 | 8.0 | 25.0 |
Specifications are based on as new condition and are subject to change without notice.
| Nominal OD (mm) |
Length (m) | Thru Bore (mm) | Tensile Yield (daN) | Torsional Limit (Nm) |
Nominal Up Latch Setting (daN) |
Nominal Down Latch Setting (daN) |
Max Pull During Delay (daN) |
Free Stroke Up/Down (mm) |
Total Stroke (mm) |
|---|---|---|---|---|---|---|---|---|---|
| 121 | 6.6 | 57 | 164 800 | 29 100 | 24 500 | 13 300 | 37 800 | 200 | 640 |
| 165 | 7.0 | 70 | 542 700 | 86 400 | 40 000 | 17 800 | 77 800 | 200 | 640 |
| 203 | 7.1 | 71 | 575 500 | 181 000 | 44 500 | 20 000 | 133 400 | 200 | 640 |
| 241 | 7.5 | 76 | 937 100 | 256 700 | 48 900 | 22 200 | 155 700 | 200 | 640 |
Specifications are based on as new condition and are subject to change without notice.
