Jars Jars Jars
15 November 2005
To jar, not to jar or to run jars at all???
Jars & their placement/use in non-horizontal wells should be based
on what you believe your most likely sticking mechanism to be. My
experience has been that stuck pipe most frequently occurs when
tripping out. In this case jars can be both very useful and
dangerous; my only strong piece of advice is that when becoming
stuck tripping out, if you have to jar ensure that your first
jarring actions are downwards - working down for a reasonable period
before considering jarring upward. Jarring upward into a problem
usually compounds the sticking mechanism.
A member from Conoco Phillips provided the following:
We do not run jars in the top hole sections, but certainly from 17
From Anne McNeill (Nexen)
I have run two set of jars - one mechanical and one hydraulic for
ERD project (Armada phase 1) - worked well (just needs to be set up
correctly), suggest speaking to Directional Company Anadrill or give
me a call.
Again a good question.
Some general points that I can think of on this subject are;
-Operators often run jars only at shallow depths (e.g. during
riserless drilling). In such situations, jar only is fundamentally
not a good idea where an accelerator must be run! Or on a risk basis,
jars are often not run at all in these sections.
- Engineers tend not to evaluate if a jar will add value or not?
(e.g. In some fields Jars are not run at all, period. As it was
evaluated that over the course of development wells, the fact of the
matter evaluated that more value was added through not running them.
e.g. When incidents did occur the found the jar either didn't work or
didn't free string anyway?)
- Jars are too-often not placed in the right place? e.g. essentially
because a jar-placement program was not run to suit each well's
design, situation and circumstances. Therefore in these cases, again
what's the point of running a tool that will not work properly, and
that often has not worked due to this fact?
In summary 'force multiplication tools' are needed if evaluated as
being value adding, vs likely risks that exisit?
Where, when properly assessed and engineered into a BHA, can provide
efficient and effective (impluse and/or impact) to get strings free
from the downhole conditions, suituations and circumstances that
But like all BHA tools, these must be determined and evaluated on
a 'horses for courses' basis. One rule cannot therefore be applied to
all locations, fields, and well designs.
Hope this helps somewhat w.r.t this subject.
Is this a trick question ??
From my experience I would recommend:-
Open water - you can leave the jars out as they are a weak link
Always have them in the string after the conductor is set. If you
don't need them, no problem - if you need them, you will be glad you
have included them.
Consider using two in long horizontal wells (one in the vertical
section of the well)
I would question the use of an accelerator deep down in a well - in
the shallower sections, it is useful.
In the current market, watch availability, ensure the Jar company
recommend where to run them and check that the wellsite team know
how to use them.
Andy Hatch (Drilling Manager at Caledonia Oil and Gas Ltd):
We used one set above the BHA in a recent 3000ft horizontal. Try
calling Dick at Randy Smith who has worthwhile advice.