poss-slider-dilling-jars

Drilling Jars

Part of the Cougar Drilling Solutions’ fleet of downhole drilling tools, the DJ10 is assembled with the ame dependable mechanical lock (latch) mechanism as the Cougar DJ6, but with the capacity to jar down hydraulically.

Benefits & Features:

  • Eliminate the need for “safety collars” found on many other jars with internal locking mechanisms
  • Prevent misfire with the internal lock

Operating Instructions

The operation of the DJ10 is similar to the DJ6 Hydraulic Mechanical Jar but the DJ10 Hydraulic Mechanical Jar requires a slight modification of the jarring procedure.

Jarring Up

In order to fire the jar upwards, the operator must determine the force or pull required to unlatch the jar to begin metering.

Formula:

Force required = lock setting + buoyed drill string weight above the jar + hole drag – pump open force.

(Pump open force = pump open area x pressure drop across the bit)

Once this pull force is exceeded and applied to the jar, it will unlatch and begin the metering sequence. During metering, the jar can be pulled with more/less force to increase/decrease the jarring impact. The force or pull used will determine the delay time of the jar until impact.

Jarring Down

To fire the jar down, the drill string is lowered applying weight to the latch that exceeds the preset mechanical latch setting. At this point, the latch will release allowing the jar to meter downwards until the jar fires, creating a downward blow.

Formula:

Force required = lock setting + pump open force + hole drag.

Once the latch is released, the applied load should not exceed the maximum allowable for pre-firing. If the jar is required to fire again, lift and reset the jar to repeat the process. To return to drilling, the operator must lift up until off bottom, and then continue drilling.

Operating Notes

Drill collars will assist the performance of the jars enhancing their performance and increasing their impact. The harder the jar is pulled, the greater the impact, the lighter the jar is pulled the lesser the impact.

It is recommended to run the jars in the lower section of the drill collars if possible. Cougar DS drilling jars should not be run at the neutral point.

Note: Maximum pre-fire load is provided in the specifications of the brochure.

English Units
OD (mm) ID (mm) Length (m) Weight (kg) Latch Setting Range (daN) Maximum Pull for Firing (daN) Maximum Pull after Firing (daN) Pump Open Area (cm2) Maximum Torque (Nm) Total Stroke (mm) Free Stroke Up (mm) Free Stroke Down (mm)
121 57 5.8 363 0 – 24,000* 37,000 169,000 71.0 29,800 483 152 152
165 63 5.6 726 0 – 50,000* 77,800 341,600 108.4 67,700 457 152 152
203 71 5.9 1,066 0 – 60,000* 129,000 512,000 181.9 142,300 457 152 152
241 71 6.1 1,497 0 – 65,000* 160,600 667,200 214.2 191,000 457 152 152
SI Units
OD (in.) ID (in.) Length (ft.) Weight (lb.) Latch Setting Range (lb.) Maximum Pull for Firing (lb.) Maximum Pull after Firing (lb.) Pump Open Area (in.2) Maximum Torque (ft.-lb.) Total Stroke (in.) Free Stroke Up (in.) Free Stroke Down (in.)
19.0 800 0 – 55,000* 84,000 380,000 11.0 22,000 19 6 6
18.5 1,600 0 – 110,000* 175,000 768,000 16.8 50,000 18 6 6
8 213/16 19.5 2,350 0 – 130,000* 291,000 1,150,000 28.2 105,000 18 6 6
213/16 20.0 3,300 0 – 145,000 361,000 1,500,000 33.2 141,000 18 6 6

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