Lubricated fishing bumper sub uses the gravitational force of a downward moving heavy weight object to create the jarring force. It is engineered to withstand strong, sustained jarring force in harsh downhole applications, severe fishing operations and deep workover operations. This bumper sub is suitable for both middle and deep downhole operation. It has an inner chamber filled with hydraulic oil to help lengthen its service life.
Lubricated fishing bumper sub is a widely used jarring tool because it is easy to operate and it assists in multiple applications. This bumper sub can provide necessary impact force in either the upward or downward direction during jarring operations. It can provide strong, continuous downward jarring force and medium, continuous upward jarring force. In addition, it can be used to engage and disengage releasable fishing tools. On top of that, this bumper sub may also act as a constant pressure drill tool.
Working Principle
● Energy conversion in jarring operation
Downward jarring forced is achieved through the conversion of stored energy to kinetic energy. When lift load is applied to the drill stem, the bumper jar is pulled open to a certain height creating a potential energy. As higher lift load is applied, the drill stem begins to accumulate stored strain energy due to the spring extension. Sudden release of the lift load will convert the stored strain energy in the drill stem to a downward acceleration force. As the drill stem accelerate
downwards, the bumper jar is released towards its closed position, releasing its potential energy. At this instant, both released energies combine, creating a large downward jarring force.
● Main factors that influence the jarring force
Hanging weight on top of drill stem with the bumper jar. Higher hanging weight will create higher jarring force.
Length of spring extension of the drill jar. Longer length of spring extension during lifting will provide a greater jarring force.
Stroke length of the bumper jar. Longer stroke length will provide a bigger jarring force.
