STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

818 Drilling and Well Completions
Types of Drilling Jars. There are two types commonly used commercial drilling
jars, combination of hydraulic (upward) and mechanical (downward) motion, and
purely mechanical action. The examples of both types follow.
Christensen-Mason Jar. (See Figure 4-172 and Table 4-103 [57].) This is a
combination tool, offering possibility to jar upwards hydraulically and to bump
downward mechanically. The jar is equipped with a special releasing (locking)
mechanism, so that the jar cannot be fired upwards until the locking system
has been released. It has a 6-in. jarring stroke upwards and 30-in. for downward
bumping [57].
Hevi-HitterrM Christensen Jar. (See Figure 4-173 [57A].) This is a mechanical
drilling jar with firing racks system applied. Its jar force is constant regardless
of torque applied.
TOOL ASSEMBLED (OPEN)
OUTER TUBE
INNER TUBE
Flex Joint fl
El
Bumping Nut ;&
J!y-in.
Compensating Piolon
(upver)
VdVO
Comprnsrting Plslon
(lower)
Locking Platon
Packing Ring Buihing
i
Mrndrrl 1
Mandrrl2
~ M a r d r r5
i
Figure 4-172. Christensen’s mason drilling jar. (Courtesy Hughes Christensen.)