U.S. patent application number 09/811811 was filed with the patent office on 2001-09-06 for downward energized motion jars.
Invention is credited to Mouton, David E., Mouton, William J. JR..
Application Number | 20010018974 09/811811 |
Document ID | / |
Family ID | 25207653 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010018974 |
Kind Code |
A1 |
Mouton, David E. ; et
al. |
September 6, 2001 |
Downward energized motion jars
Abstract
An apparatus for dislodging stuck tools downhole, which includes
a tool body; a mandrel moveable within the tool body; a spring
member for allowing the mandrel to move with jarring force within
the tool body when actuated; actuating fluid allowing the mandrel
to travel a portion of the distance in a controlled manner, and at
a predetermined point, accelerate its travel to provide a jarring
force against the tool body; wherein the actuating fluid includes a
first and second volumes of fluid through which a portion of the
mandrel travels; the first volume providing controlled travel, and
the second volume allowing accelerated travel of the mandrel.
Inventors: |
Mouton, David E.;
(Mandeville, LA) ; Mouton, William J. JR.; (New
Orleans, LA) |
Correspondence
Address: |
GARVEY SMITH NEHRBASS & DOODY, LLC
THREE LAKEWAY CENTER
3838 NORTH CAUSEWAY BLVD., SUITE 3290
METAIRIE
LA
70002
|
Family ID: |
25207653 |
Appl. No.: |
09/811811 |
Filed: |
March 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09811811 |
Mar 19, 2001 |
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09437871 |
Nov 10, 1999 |
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60110232 |
Nov 30, 1998 |
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Current U.S.
Class: |
166/301 ;
166/178; 166/304; 175/297; 175/299; 175/304 |
Current CPC
Class: |
E21B 31/113
20130101 |
Class at
Publication: |
166/301 ;
166/178; 175/299; 166/304; 175/304; 175/297 |
International
Class: |
E21B 031/113 |
Claims
1. An apparatus for dislodging stuck tools downhole, comprising: a.
a tool body; b. a mandrel moveable within the tool body; c. spring
means defining a compressible force as the mandrel is moved to a
first cocked position; d. means for moving the mandrel downward
relative to the tool body within a controlled time frame allowing
an operator time to slack off placing compression in drill string,
so that at a point in its travel, the mandrel is able to accelerate
its travel, and assisted by the spring means, to provide a jarring
force against the tool body.
2. The apparatus in claim 1, wherein the means for moving the
mandrel downward relative to the tool body comprises first and
second volumes of fluid through which a portion of the mandrel
travels; the first volume providing controlled travel, and the
second volume allowing accelerated travel of the mandrel.
3. The apparatus in claim 1, wherein the mandrel further comprises
a hammer portion which makes jarring contact with the upper end of
the tool body.
4. The apparatus in claim 1, further comprising a one-way valve for
allowing rapid pulling of the mandrel upward in order to cock the
tool into the jarring mode.
5. The apparatus in claim 2, wherein the first volume defines a
reduced travel space for controlling the speed of travel of the
mandrel.
6. The apparatus in claim 2, wherein the second volume defines an
enlarge travel space for allowing rapid movement of the mandrel to
provide a jarring contact.
7. The apparatus in claim 1, wherein the spring means further
comprises a coiled spring or a compressible gas or fluid medium
within the apparatus.
8. An apparatus for dislodging stuck tools downhole, comprising: a.
a tool body; b. a mandrel moveable upward within the tool body; c.
spring means compressible as the mandrel moves upward relative to
the tool body; d. means for moving the mandrel downward relative to
the tool body within a controlled time frame allowing an operator
time to slack off placing compression in the drill string; e. the
spring means providing a means to accelerate the downward travel of
the mandrel at a predetermined point in its downward travel to
effect a downward jar to dislodge the stuck object.
9. The apparatus in claim 8, further comprising first and second
volumes of fluid through which a portion of the mandrel travels;
the first volume providing controlled travel, and the second volume
allowing accelerated travel of the mandrel.
10. A method of dislodging stuck tools downhole, comprising the
following steps: a. providing a self-contained body section, having
a mandrel moveable relative to the body section, the lower end of
the body engaged to drill string below and an upper end of the
mandrel portion attached to the drill string above the body
portion; b. pulling upward on the mandrel portion to a first cocked
position; c. providing a spring means defining a compressible force
within the body section as the mandrel is pulled upward; d.
releasing the mandrel to travel in a controlled downward movement
so that an operator is allowed to slack off putting compression in
the drill string; then e. accelerating the downward travel of the
mandrel by the compressed spring means so that a hammer portion of
the mandrel imparts a striking force to the upper end of the body
section.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of co-pending U.S. patent
application Ser. No. 09/437,871, filed Nov. 10, 1999, which is
incorporated herein by reference.
[0002] Provisional Patent Application Ser. No. 60/110,232, filed
Nov. 30, 1998, is hereby incorporated herein by reference
thereto.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0003] Not applicable
REFERENCE TO A "MICROFICHE APPENDIX"
[0004] Not applicable
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] The apparatus of the present invention relates to jarring
tools used in downhole drilling. More particularly, the present
invention relates to an improved apparatus for jarring stuck tools,
including pipe, downhole and a method of achieving same.
[0007] 2. General Background of the Invention
[0008] In the art of drilling wells for recovery of hydrocarbons,
the process incorporates a drill string which comprises a plurality
of threaded tubular members such as drill pipe being approximately
30 foot each in length, the drill pipe threaded end to end which is
then used to rotate the drill bit either from the surface or
through the use of a drill motor which would rotate the bit without
the rotation of the drill pipe itself. Often times during that
process, the drill string will become lodged at a certain point
along its length within the borehole.
[0009] In the efforts to dislodge the drill pipe or other tools
lodged downhole, a type of tool known as a jarring tool would be
used in such an attempt. In the current state of the art, jarring
tools as they currently utilize may be used to either jar the stuck
or the lodged portion of pipe either in the up or down direction,
depending on the makeup of the tool. In most cases, it would be
more desirable to jar down on the pipe than to jar up. The reason
for this is that drill pipe will usually get lodged when it is
being pulled up as opposed to being moved downward, so jarring
downward will more likely free the pipe. In such a case, the pipe
is probably wedged against an obstruction caused by the upper
movement of the pipe, and jarring upward may tend to wedge the
debris around the section of pipe even tighter.
[0010] Methods of downward jarring which are currently used in the
art includes applying compression on the drill string to which a
down jar has been attached, whereby the jar releases at a pre-set
load, allowing the hammer of the jar to freely travel a short
distance impacting the anvil of the tool, delivering a downward
blow. The effectiveness of this method has limitations, due to
compressional buckling of the drill string, as well as drag.
Therefore, it is often difficult to achieve a large downhole
jarring force in a vertical well, and the problem is exacerbated in
the horizontal portion of a directional drilling operation. A jar
in the upward direction can be attached to the top of the stuck
pipe or tool, and the jar can be pulled upward until it is tripped.
While this type of jarring can produce more force than downward
jarring, it is typically in the wrong direction for most instances
of stuck pipe. Certain patents have been obtained which address the
method of jarring pipe loose from a borehole, and these will be
provided in the prior art statement submitted herewith.
BRIEF SUMMARY OF THE INVENTION
[0011] The apparatus of the present invention solves the problems
in the art in a simple and straight forward manner. What is
provided is an apparatus for jarring a portion of drill string
lodged within a borehole, by jarring downward using tension versus
compression. The apparatus would include a first member for
attaching a first lower end of the apparatus to the upper end of
the lodged tool or pipe through a threadable attachment; there
would then be provided a second member for attaching a second end
of the apparatus to a drill string on its upper end portion; there
is further provided a third anvil or hammer member which is
triggered by a spring having stored compressional force transferred
by tension from the drill string to the apparatus when the drill
string is pulled upward. There is also provided an actuator for
rapidly releasing the tension force provided by the spring downward
onto the stuck pipe in order to provide an impacting, downward
force onto the pipe in an effort to dislodge the pipe. There is
further provided a slow release mechanism for slowly releasing the
tension force stored by the spring.
[0012] Therefore, it is the principal object of the present
invention to provide a tool for dislodging drill pipe down a
borehole, which provides for a downward jarring on the stuck pipe
or tool to facilitate dislodging of same;
[0013] It is another principal object of the present invention to
provide an apparatus for dislodging pipe or tools from a borehole
by imparting a downward force, yet disallowing the weight of the
hammer member from imparting additional, undesirable force on the
surface mechanisms; It is a further object of the present invention
to provide a jarring tool which has an internal mechanism for
regulating the amount of force that is imparted onto the stuck
object lodged within the borehole, yet provides for sufficient
force to dislodge the pipe or tool within the borehole;
[0014] It is a further object of the present invention to provide a
method of dislodging tools stuck down a borehole which includes
providing a tool having a first portion secured to the lodged tool,
a second portion secured to the tubing above the tool, and a third
portion defining a means for imparting jarring force against the
stuck tool, while moving independently of the second portion to
prevent undesired force on the elements above the tool.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a further understanding of the nature, objects, and
advantages of the present invention, reference should be had to the
following detailed description, read in conjunction with the
following drawings, wherein like reference numerals denote like
elements and wherein:
[0016] FIG. 1 illustrates an overall outer view of the preferred
embodiment of the apparatus of the present invention as it would be
attached to drill pipe above and the stuck pipe or object below the
apparatus;
[0017] FIG. 2 illustrates an outer view of the apparatus as seen in
FIG. 1 moving into the cocked position for firing;
[0018] FIG. 3 illustrates an outer view of the apparatus in FIG. 1
fully cocked and ready to be fired in the bore hole;
[0019] FIGS. 4 and 5 illustrate views of the preferred embodiment
of the apparatus of the present invention as it is fired to impart
downward force on the drill pipe lodged in a borehole;
[0020] FIG. 6A illustrates an exploded partial view of the three
members of the apparatus as they relate to one another; while
[0021] FIG. 6B illustrates a partial cut away view of the jarring
lower portion of the apparatus as it is being moved into the firing
position,
[0022] FIG. 7 illustrates a partial cut away view of the lower
jarring portion of the apparatus of the present invention as it is
ready to be fired;
[0023] FIG. 8 illustrates a partial cut away view of the lower
jarring portion of the apparatus of the present invention at the
point that the apparatus is fired;
[0024] FIGS. 9A and 9B illustrate views of the latching means used
in the apparatus of the present invention;
[0025] FIG. 10 illustrates a partial view of the internal cut away
provided in the tension member of the present invention;
[0026] FIG. 11A illustrates a cross section view of the secondary
metering system used in the jarring mechanism working in
conjunction with the fluid reservoir in the present invention,
while FIGS. 11B and 11C illustrate the drill collars and tension
tube utilized in the present invention; and
[0027] FIGS. 12 through 14 illustrate views of an additional
embodiment of the apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0028] FIGS. 1 through 11C illustrate the first preferred
embodiment of the present invention by the numeral 10, as it would
generally appear undertaking the process of dislodging a section of
pipe or tools from the borehole. It should be noted that in
general, apparatus 10 comprises three principal components. The
first component comprises an upper section or member 12 secured to
tubing, such as a drill pipe, coil tubing, or wireline, depending
on the type of tool lodged downhole. There is provided a second
lower member 16 secured to the tool or drill pipe lodged downhole,
and a third "jarring" member 27, comprising the hammer portion of
the apparatus, which when fired, imparts downward force, striking
the lower member 16 secured to the stuck tool or pipe.
[0029] Turning first to FIG. 1, there is illustrated apparatus 10
secured at the upper portion 12 to a section of drill pipe 14 and
at it's lower portion 16 to a tool or a portion of drill pipe 18
which has become lodged down the borehole by formation 20. As
further illustrated, the third "jarring member" 27 of apparatus 10
would further comprise a plurality, or preferably three drill
collars 22, 24, 26, in succession, in order to provide the
requisite amount of mass to the "jarring" member 27 of the
apparatus when the jarring takes place, so as to free the stuck
pipe 18.
[0030] In FIG. 2, there is illustrated a portion of the upper
portion 12 which includes an actuator sub 30, including the tension
tube 34, which is secured to the upper portion of drill pipe 14
through the upper attachment portion 32 of upper portion 12. The
upper attachment portion 32 is secured to the tension tube portion
34 which would be pulled upward to compress an internal spring (not
illustrated), and to set the firing mechanism so that the jarring
portion 27 of the apparatus is locked in place ready to fire as
seen in FIG. 3. Upon reaching a certain point of travel, the drill
pipe 14 would be lowered as seen in FIG. 4, the jarring unit 27
would be fired, and the internal spring would expand rapidly
forcing the hammer and connected drill collars 22, 24, 26 to impact
the shoulder 38 of the jarring unit 27 against shoulder 40 of upper
portion 42 of the lower portion 16 of tool 10, as seen in FIG. 5,
which in turn would jar the stuck tool or pipe 18. This would be
repeated until the tool is free. FIGS. 1 through 5 illustrate a
general outer views of the operation of the apparatus 10, while
FIG. 6A illustrates the relationship of the three members of the
apparatus, namely the upper member 12, the lower member 16, and the
jarring member 27, as they slidably engage into one another to form
the composite apparatus. This interrelationship will be explained
for fully, through FIGS. 6B through 11C which illustrate the
details of the apparatus in its operation.
[0031] FIG. 6B illustrates a partial cutaway view of jarring member
27 of the apparatus of the present invention moveable within the
lower portion 16 secured to a lodged tool 18. As illustrated, the
jarring member 27, includes a tension tube 34. The hammer portion
of the tool has an upper head portion 52 moveable within the
jarring member 27 and would be slidably engaged within outer body
56 of lower attachment portion 16. Hammer sub 54 would terminate at
a flanged collar connector 58, having an internal shoulder 60, with
an o-ring 62 for sealing the space between shoulder 60 and tension
tube 34. Below the collar connector 58 there is provided the
cylindrical body 64 which terminates in an outer flange 66 for
supporting the lower end of spring means 68 as illustrated. For
purposes of construction, spring means 68 would preferably comprise
a belleville spring, of the type known in the industry, or may
comprise a fluid or hydraulic spring means. The inner face of the
lower end of cylindrical body 64 would include a continuous
concavity 70 around its inner face so as to accommodate the latch
means 72 as seen in the figures, and as will be discussed further.
As seen further in the FIG. 6B, the tension tube 34 terminates in a
flanged collar portion 74 to raise and cock the hydraulic piston
76. As illustrated in FIG. 6B, the latch means 72 is engaged within
the concavity 70 around the inner face of the body 64. When upward
force is placed upon the tension tube 34, by pulling on the upper
tubing, the flanged collar portion 74, which has engaged the lower
end 77 of hydraulic piston 76, begins to lift the cylindrical body
64, which in turn compresses the spring 68.
[0032] Turning now to the lower portion of the jarring portion 27
there is provided a hydraulic means for sustaining the
compressional energy now stored by spring 68, to allow the tension
to be to be lowered to fire the mechanism. As illustrated in FIG.
7, there is provided a hydraulic reservoir 78 which is formed
between a first upper flanged collar 80, and a second lower flanged
collar 82, in the wall of the outer body 56 of the jarring member
27. As seen in FIGS. 7 and 8, the reservoir 78 contains a quantity
of hydraulic fluid 81, which is placed in the reservoir via access
screws 83, allowing access into reservoir 78. It should be noted
that the inner surfaces of each flanged collar 80, 82 is provided
with an o-ring 85 so as to maintain hydraulic fluid 81 within the
reservoir during operation of the tool. The piston 76 would include
a check valve portion 84, having a one way check valve 86, so that
as the piston 76 moved upward or downward, the check valve 86
positioned on a flanged collar 87 would allow the fluid to travel
between those points above and below the flanged collar 87 so the
piston may move upward rapidly but downward movement is retarded
due to the metering action of the piston.
[0033] In FIG. 6B, the piston 76 has been raised to a point where
spring 68 is fully compressed and the tool is ready to fire. As
seen in FIG. 7, the tension tube is lowered where upon the latch
means 72 reaching the conical groove 90 in the wall of tension tube
34, the latch means 72 disengages from conical groove 70 in the
wall of tension tube actuator 54, and moves into conical groove 90
in the wall of tension tube 34. When this occurs, spring 68 is
allowed to expand, and together with the mass provided by drill
collars 22, 24, 26, provides significant downward force on the
jarring member 27, so that the head 52 makes a substantial impact
on the upper end of outer body 56, which imparts a downward jar to
the stuck drill pipe 18. It is important to note that because of
the three member configuration of the apparatus, the tension tube
34 allows free movement of the mass of the three drill collars 22,
24, 26, attached to the actuator portion 54 so that when the
jarring function of the tool is undertaken as explained above, the
drill string is isolated from potential damage that would occur if
the upper tubing was directly attached to the jarring member 27.
Furthermore, drag forces are minimized on the jarring system
because of its independent movement.
[0034] FIGS. 9A through 9C illustrate the latch mechanism 72 in its
component parts. As seen if FIG. 9A, there is illustrated the latch
means 72 positioned atop the piston body 76. There is also
illustrated the concavity or conical groove 70 in body 56, in which
the latch 72 is positioned. In this position, the tool is cocked
and unfired, as seen in FIG. 6B. FIG. 10 illustrates the groove 90
which is formed completely around the wall of tension tube 34, into
which latch 72 would slide to trigger the apparatus, as discussed
earlier in FIG. 8.
[0035] For understanding the relationship between latch means 72
and the piston body 76, reference is made to FIG. 9B. As
illustrated, the latch means 72 comprises four segments 72A through
72D which include a quarter-round an upright body portion 77 and a
lower dovetail oval-shaped portion 79 which would engage into a
dovetail oval-shaped opening 81 in piston 76. Therefore, when each
of the segments 72A through 72D are engaged in openings 81, the
latch means 72 is formed in the circular configuration for
operating in the tool. This engagement as provided, allows the
movement of the latch member 72 from the position engaged in groove
or concavity 70 while the tool is cocked, to the position in groove
or concavity 90, when the tool is fired. Again, FIG. 10 illustrates
the groove 90 formed in the wall of the tension tube 34 which
receives the four components 72A through 72D when the tool is
fired.
[0036] Although some discussion was made earlier regarding the
hydraulic fluid reservoir 78, its function as a primary metering
device has not been fully discussed. Returning first to FIG. 7,
which illustrates the tool cocked and ready for firing. In the
event that a driller should decide not to fire the apparatus after
the apparatus is in position for firing as illustrated in FIG. 7,
or the driller would make a decision to raise the entire drill
string due to freeing of the pipe, the spring member 68 together
with the hydraulic piston 76, with the hydraulic flange 77 and the
latch mechanism 72 will slowly move downward and release the stored
energy of the jarring mechanism within a designed period of time.
The further reduction of recessed area 90 at point 94 would allow
the driller to lower the drill string to fire the jar immediately
with minimum loss of the spring member 68 compression due to the
varying hydraulic bleed of the hydraulic metering system in place.
As was stated earlier, as the actuator is lowered to its length, in
the stroke, the compression in the spring 68 is maintained by the
hydraulic pressure within hydraulic fluid reservoir 78, by means of
a one-way check valve 84. When the machine opening 90 of the
tension tube actuator 54 reaches the segmented latch mechanism 72,
the latch mechanism 72 is then forced out of the way of the
hydraulic piston 76, releasing the lower portion 42 of the tool 10
to impact the shoulder 40 of the jarring tool 52 at impact surface
38.
[0037] Therefore, if the tension tube actuator 34 is not lowered
within a few minutes of the raising of the drill string, the
hydraulic metering assembly will slowly uncock the spring 68 as the
hydraulic fluid 81 within the reservoir 78 moves slowly from the
lower portion to the upper portion of the reservoir. In this
manner, the tension in the spring 68 will be released long before
the jarring tool 52 reaches the surface eliminating a potential
safety hazard.
[0038] After the tool has either fired or moved into the position
of having been uncocked as described above, the tool then must be
"re-cocked" in order to undertake an additional firing. For
example, in FIG. 8 there is illustrated the tool after the hammer
52 has fired and the latch means has moved from the cocked position
set within opening 70, to the firing position after it is moved
into opening 90. Of course, after the tool has fired, it is
necessary to recock the tool into the position as seen in FIG. 7.
therefore, the tension tube 34 must be lowered into position so
that the latch 72 would reengaged into opening 70. In order to
accomplish this, the hydraulic fluid 81 must be re-bled back into
the lower portion of the reservoir 78. Since the return of the
fluid in that manner would result in the tool being recocked very
slowly, reference is made to FIG. 11A, where there is illustrated a
secondary metering component 91, which is an opening formed in the
wall of tension tube actuator portion 54 so that the hydraulic
fluid may flow into the metering component 91 and allow the tool to
be recocked rather quickly rather than having to allow for the
fluid to completely flow to the lower portion of the reservoir 78.
After this is accomplished, the tool is ready to be refired as seen
in FIG. 7.
[0039] The first embodiment of the present invention can provide
significantly more compressive force to jar with, as tension is
easily applied to the apparatus, whereas in conventional jars,
precompression is difficult to achieve due to the buckling of the
drill string, especially in horizontal directional drilling
operations. With the present invention, one can also jar over a
much longer stroke than existing jars due to the fact that the tool
decouples the drill string from the jarring apparatus via the tube
member 34. Instead of a 4 to 6 inch jarring stroke, a massive
jarring stroke of from 3-5 feet can be obtained with the apparatus
of the present invention. The result in order of magnitude, is
approximately ten fold, of an increase of inline jarring energy. In
this invention, the jarring mass of the three interconnected drill
collars spans a total of 95 feet. In existing art, the typical
drill string must move over several thousands of feet to effect a
conventional jarring system.
[0040] FIGS. 12 through 14 illustrate a second principal embodiment
of the apparatus of the present invention. As is illustrated in the
figures, tool 101 houses a mandrel 102 including a threaded
connection 130 at the upper end of the mandrel 102 for threadably
engaging to an upper portion of pipe or the like. Mandrel 102
includes a hammer portion 103, which further comprises an external
spline 104 for engaging an internal spline 105 formed on tool 101,
for allowing mandrel 102 to move upward and downward relative to
the tool 101 and transmit torque through the outer housing of the
tool 101. Threaded connection 106 provides a means of assembly
between the upper portion of mandrel 102 and the next portion of
the mandrel.
[0041] There is further provided a spring means 107, which may be a
coiled or other type of spring, or comprised of a compressible gas
or liquid. Spring means 107 is housed between the outer wall of
mandrel 102 and within an internal cylinder 108 of the tool 101 and
engaged on its lower end by a piston 113 of the mandrel 102. The
upper end of spring means 107 is engaged or contained on a shoulder
132. Connection 115 provides assembly joint of the lower end of
cylinder 108.
[0042] There is further provided a seal 114, which maintains spring
means 107 isolated from the fluid volumes below it. This seal 114
allows spring means 107 to travel or, in the case of a compressible
gas or liquid be compressed between a compressed state, as a high
pressure means, to its released state as a low pressure means,
while contained within cylinder 108 of tool 101. Cylinder 108 is
sealed off from the metering fluid 119 by seal 117. The metering
fluid 119 comprises a first metering volume 120 and release volume
121. Triggering shoulder 129 separates the metering volume 120 from
the release volume 121. Shoulder 123 provides a slow metering means
for metering volume 120 and also includes a one way valve 123a
which allows fluid to travel below the shoulder 123, as the mandrel
102 is pulled upward to allow for rapid cocking of the tool. Joint
124 provides connection for assembly, while filler port 125
provides a means for filling of metering fluid 119, into volumes
120 and 121. Cap 126 seals the filler port 125 after the metering
fluid is in the tool 101.
[0043] Turning now to FIG. 13, the tool 101 would be cocked from
its first position, as seen in FIG. 12, by an upward pull on
mandrel 102 compressing and energizing spring means 107 as well as
displacing shoulder 123 from the release volume 121 into the
smaller area of the metering volume 120. Upon release of the upward
pull of mandrel 102, because of the small area of the metering
volume 120, and the one-way valve 123a, the mandrel travels slowly
downward, in the direction of arrow 127, to allow time for the
operator to place the tool 101 in compression, thereby allowing
subsequent firing of the tool without imparting a load on the drill
string attached at the upper end to mandrel 102.
[0044] In FIG. 14, shoulder 123 has now travelled past trigger
point shoulder 122, allowing piston 123 to move freely through
release volume 121, and thus firing the tool. This motion is caused
by high pressure energy provided by spring means 107, which was
compressed into a high pressure state by the upward pull of mandrel
102 by the attached drillstring.
[0045] The downward jarring is accomplished by contact between
hammer member 103 on mandrel 102 making a jarring contact with
anvil 105a, on the upper end of tool 101, as shown in FIG. 1.
[0046] The foregoing embodiments are presented by way of example
only; the scope of the present invention is to be limited only by
the following claims.
* * * * *