In the past, many drilling jar types and models existed. But from a practical usage standpoint, certain models are predominantly utilized.
1. Surface Adjustable Mechanical Drill Jars
These tandem jars enable surface adjustment of release force as needed. The short overall length and flexible operation are advantageous.
Common surface adjustable mechanical drilling jar sizes include:
- QJ120A (4 3/4")
- QJ178A (7")
Its technical keys are the locking mechanism and release force adjustment mechanism design and machining. The adjustment must be accurate and reliable. The locking mechanism must have a long service life. This requires high standards for component design, machining precision, material selection, and heat treatment.
The locking mechanism uses a lug profile collar which is released by elastic sleeve deformation under pressure.
2. Non-Adjustable Mechanical Drilling jars
These jars utilize a lug locking collar retained by a spring pack. Release occurs when the collar overcomes the spring preload force to spread open. The release force is pre-set during assembly and does not require field adjustment. The absence of an adjustment mechanism allows a more compact design and reliable operation.
3. Hydraulic Jars
Hydraulic jars use the damping effect of hydraulic fluid flow through restricted passages as the locking mechanism. Sudden fluid bypass triggers release and impact within the tool, transmitting vibration into the drill string. Strict requirements exist for sealing design, seal materials, and precision machining.
Due to the operating principle, hydraulic jars can only jar in one direction, normally upward.
4. Surface-Activated Downward Jarring Tool
Surface downward jarring tools are used at the rig floor to apply a downward jarring impact to the stuck point. The simple mechanism lacks complex seals or torque transmission. Convenient surface-only operation provides advantages. Traditional tools used friction cones with inherent release force instability and lockup risks at higher loads, presenting safety hazards.
Choose VIGOR as your supplier, Vigor has different types of drilling jars available, including mechanical, full-hydraulic, integral mechanical, hydro-mechanical, and mechanical & hydraulic jars, please contact us at info@vigorpetroleum.com.
