Two way hydraulic drilling jar

A two way hydraulic drilling jar which includes a tubular housing having an interior surface defining an interior bore. A mandrel is provided having an exterior surface. The mandrel is telescopically received within the interior bore of the tubular housing. The exterior surface of the mandrel has an enlarged diameter portion. An annular valve member is provided having a first end, a second end, and an interior surface defining an interior bore. The mandrel extends through the interior bore of the valve member. The valve member is confined with capability of limited axial movement between two shoulders projecting from the interior surface of the housing. The interior bore of the annular valve member receives the enlarged diameter portion of the mandrel in close fitting relation. At least one fluid bypass channel is disposed in one of the valve member and the enlarged diameter portion of the exterior surface of the mandrel. The fluid bypass channel extends longitudinally between the first end and the second end of the annular valve member. When the enlarged diameter portion of the mandrel is positioned in close fitting relation within the interior bore of the valve member, fluid can slowly bleed past to create a time delay before the enlarged diameter portion mandrel exits the interior bore of the valve member.

FIELD OF THE INVENTION 
The present invention relates to a two way hydraulic drilling jar. 
BACKGROUND OF THE INVENTION 
Most hydraulic jars are capable of jarring up, but not down. It is 
difficult to jar in both directions using a single hydraulic valve, due to 
problems in getting the valve to center itself properly in the 
restriction. For that reason most two way hydraulic jars, use two 
hydraulic valves, one of which is inverted. 
U.S. Pat. No. 5,123,493 is an example of a two way hydraulic drilling jar 
that utilizes a single valve. U.S. Pat. No. 5,123,493 discloses an 
hydraulic drilling jar which is constructed of a mandrel that is 
telescopically received within a tubular housing. An annular fluid chamber 
is formed between the mandrel and the housing. An annular valve member is 
disposed within the fluid chamber and is secured between two projecting 
shoulders on the exterior surface of the mandrel. As relative movement of 
the mandrel and the housing occurs the valve member moves axially in the 
fluid chamber. The interior surface of the housing has a restriction. The 
valve member moves freely in the fluid chamber until it reaches the 
restriction. Bypass passages are provided to enable fluid to bleed past 
the valve member when the valve member is positioned within the 
restriction. Should the drill string become stuck, the drill string is 
placed in either compression or tension, depending upon whether it is 
desired to jar up or jar down. The force exerted upon the drill string 
tends to cause relative movement of the mandrel and the housing. Only 
limited relative movement can occur, however, until after a time delay 
during which sufficient fluid bleeds through the bypass passages to enable 
the valve member to come out of the restriction. Once the valve member 
comes out of the restriction, the mandrel and housing are free to move and 
a hammer on one is brought into engagement with an anvil on the other in a 
violent jarring impact. 
SUMMARY OF THE INVENTION 
The present invention relates to an alternative configuration for a two way 
hydraulic drilling jar that utilizes a single valve. 
According to the present invention there is provided a two way hydraulic 
drilling jar which includes a tubular housing having a first end, a second 
end and an interior surface defining an interior bore. A mandrel is 
provided having a first end, a second end and an exterior surface. The 
mandrel is telescopically received within the interior bore of the tubular 
housing. The exterior surface of the mandrel has an enlarged diameter 
portion. First sealing means are disposed between the interior surface of 
the housing and the exterior surface of the mandrel at the first end of 
the housing. Second sealing means are disposed between the interior 
surface of the housing and the exterior surface of the mandrel at the 
second end of the housing. An annular fluid chamber is formed between the 
exterior surface of the mandrel and the interior surface of the housing. 
The annular fluid chamber has a first end defined by the first sealing 
means and a second end defined by the second sealing means. An annular 
valve member is provided having an annular sidewall, a first end, a second 
end, an exterior surface, and an interior surface defining an interior 
bore. The annular valve member is disposed within the fluid chamber with 
the mandrel extending through the interior bore. The valve member is 
confined with capability of limited axial movement between two shoulders 
projecting from the interior surface of the housing. The interior bore of 
the annular valve member receives the enlarged diameter portion of the 
mandrel in close fitting relation. At least one hammer is provided on one 
of the mandrel and the housing. A first anvil is provided on the other of 
the mandrel and the housing that engages the at least one hammer in a 
jarring impact upon relative telescopic movement of the mandrel and the 
housing in a first direction. A second anvil is provided on the other of 
the mandrel and the housing that engages the at least one hammer in a 
jarring impact upon relative telescopic movement of the mandrel and the 
housing in a second direction. At least one fluid bypass channel is 
disposed in one of the valve member and the enlarged diameter portion of 
the exterior surface of the mandrel. The fluid bypass channel extends 
longitudinally between the first end and the second end of the annular 
valve member. When the enlarged diameter portion of the mandrel is 
positioned in close fitting relation within the interior bore of the valve 
member, fluid can slowly bleed past to create a time delay before the 
enlarged diameter portion mandrel exits the interior bore of the valve 
member resulting in the hammer and the anvil engaging in a violent jarring 
impact. 
Although beneficial results may be obtained through the two way hydraulic 
drilling jar, as described, there are measures that can be taken to 
provide the fluid bypass channel with a variable flow depending upon the 
positioning of the enlarged diameter portion of the mandrel relative to 
the interior bore of the annular valve member. These modifications are of 
assistance in ensuring positioning of the enlarged diameter portion of the 
mandrel in the interior bore in preparation for jarring. 
One approach to creating a variable fluid flow is to utilize a pair of 
radial fluid bypass ports. In accordance with this approach, A first 
radial fluid bypass port extends through the annular sidewall of the 
annular valve member adjacent the first end. A second radial fluid bypass 
port extends through the annular sidewall of the annular valve member 
adjacent the second end. Fluids can communicate between the interior 
surface and the exterior surface of the annular valve member. The radial 
fluid bypass ports are in fluid communication with the at least one fluid 
bypass channel, such that when a force is exerted upon the mandrel to push 
the enlarged diameter portion on the exterior surface of the mandrel into 
the close fitting interior bore of the annular valve member and the 
annular valve member is pushed against one of the projecting shoulders on 
the interior surface of the housing thereby blocking the at least one 
fluid bypass channel, hydraulic fluid flowing along the at least one fluid 
bypass channel is able to exit through one of the radial fluid bypass 
ports notwithstanding blockage of the at least one fluid bypass channel by 
one of the shoulders. This continues until the radial fluid bypass ports 
are also blocked by the enlarged diameter portion on the exterior surface 
of the mandrel, at which time the flow of hydraulic fluid through the 
radial fluid bypass ports is restricted thereby slowing the mandrel for 
positioning within the interior bore of the valve member in preparation 
for jarring. 
Another approach to variable fluid flow is to utilize at least one radial 
bypass port, in combination with a plurality of fluid bypass channels. The 
at least one radial bypass port extends between some of the plurality of 
fluid bypass channels and the at least one of said plurality of fluid 
bypass channels that is positioned intermediate the spacer member and the 
interior surface of the valve member. When a force is exerted upon the 
mandrel to push the enlarged diameter portion on the exterior surface of 
the mandrel into the close fitting interior bore of the annular valve 
member and the annular valve member is pushed against one of the 
projecting shoulders on the interior surface of the housing thereby 
blocking some of the plurality of fluid bypass channels, hydraulic fluid 
flowing along the some of the plurality of fluid bypass channels that are 
blocked is able to pass through the at least one radial fluid bypass port 
to the at least one of said plurality of fluid bypass channels that is 
positioned intermediate the spacer member and the interior surface of the 
valve member which is not blocked. 
Another approach that can be used alone or in combination with the other 
approach described above, is to utilize metering devices. In accordance 
with this approach, means for metering the flow of hydraulic fluid is 
provided in the at least one fluid bypass passage. Where metering devices 
are used it may be advisable to also provide means for filtering 
contaminants from the flow of hydraulic fluid. Contaminants will, of 
course, adversely effect the operation of the metering device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiment, a two way hydraulic jar generally identified by 
reference numeral 12, will now be described with reference to FIGS. 1a 
through 7. 
Referring to FIGS. 1a and 1b, there is illustrated a two way hydraulic 
drilling jar 12 into which an annular valve member 10 is intended to be 
incorporated. Hydraulic jar 12 includes a mandrel 14 that is 
telescopically received within a tubular housing 16. Mandrel 14 has a 
first end 18, a second end 20 and an exterior surface 22. To facilitate 
assembly mandrel 14 comes in two threadedly connected sections 14a and 
14b. Housing 16 has a first end 24, a second end 26, and an interior 
surface 28 defining an interior bore 29. To facilitate assembly, housing 
16 comes in a number of threadedly connected sections 16a, 16b, 16c, and 
16d. An annular fluid chamber 30 is formed between mandrel 14 and housing 
16 by a first annular seal 32 and a second annular seal 34. First annular 
seal 32 is positioned at first end 24 of housing 16 and engages exterior 
surface 22 of mandrel 14. Second annular seal 34 is positioned at second 
end 20 of mandrel 14 and engages interior surface 28 of housing 16. 
Annular valve member 10, constructed in accordance with the teachings of 
the present invention, is disposed within annular fluid chamber 30, as 
will be hereinafter further described. Fluid chamber 30 can be said to be 
divided into two portions 38 and 40, positioned on either side of annular 
valve member 10. A hammer 42 is provided at the connection between mandrel 
components 14a and 14b. Hammer 42 has two contact faces; a first contact 
face 44 and a second contact face 46. A shoulder jutting out from interior 
surface 28 of housing 16 serves as a first anvil 48. First anvil 48 
engages first contact face 44 of hammer 42 in a jarring impact upon 
relative telescopic movement of mandrel 14 and housing 16 in a first 
direction. A shoulder jutting out from interior surface 28 of housing 16 
serves as a second anvil 50. Second anvil engages second contact face 46 
of hammer 42 in a jarring impact upon relative telescopic movement of 
mandrel 14 and housing 16 in a second direction. 
Annular valve member 10 will now be described. Referring to FIGS. 3 and 4, 
annular valve member 10 has an annular sidewall 52, a first end 54, a 
second end 56, an exterior surface 60 and an interior surface 58 defining 
an interior bore 59. Annular valve member is confined with capability of 
limited axial movement between two shoulders 62 and 64 positioned on 
interior surface 28 of housing 16. Mandrel 14 extends through interior 
bore 59 of annular valve member 10. Mandrel 14 has an enlarged diameter 
portion 36 that is received in close fitting relation within interior bore 
59. A longitudinal fluid bypass channel 66 extends along exterior surface 
60 of annular valve member 10 between first end 54 and second end 56. 
Longitudinal fluid bypass channel 66 is positioned immediately adjacent 
housing 16 between shoulders 62 and 64 which confine annular valve member 
10 to a severely limited range axial movement. When annular valve member 
10 moves axially in one direction, longitudinal fluid bypass channel 66 is 
blocked by shoulder 62. When annular valve member 10 moves axially in the 
other direction, longitudinal fluid bypass channel 66 is blocked by 
shoulder 64. A first radial fluid bypass port 68 and a second radial fluid 
bypass port 69 extend through annular sidewall 52 of annular valve member 
10, such that fluids can communicate between interior surface 58 and 
exterior surface 60 of annular valve member 10. Radial fluid bypass ports 
68 and 69 are in fluid communication with longitudinal fluid bypass 
channel 66. First radial bypass port 68 is positioned adjacent first end 
54 of annular valve member 10 and second radial bypass port 69 is 
positioned adjacent second end 56 of annular valve member 10. 
FIG. 3 illustrates enlarged diameter portion 36 of mandrel 14 entering 
interior bore 59 of annular valve member 10 in order to reset hydraulic 
drilling jar 12. The direction of movement of housing 16 is illustrated by 
arrow 70. As soon as a force is exerted upon mandrel 14, one of shoulders 
62 or 64 is brought into engagement with annular valve member 10. In view 
of the direction of movement, shoulder 64 is shown engaging second end 56 
of annular valve member. Shoulder 64 blocks hydraulic fluid exiting 
longitudinal fluid bypass channel 66 via second end 56. Hydraulic fluid, 
therefore, flows along longitudinal fluid bypass channel 66 exiting 
through second radial fluid bypass port 69 until second radial fluid 
bypass port 69 is blocked by the entry into interior bore 59 of annular 
valve member 10 of enlarged diameter portion 36 of mandrel 14. Referring 
to FIG. 4, as enlarged diameter portion 36 of mandrel 14 advances into 
interior bore 59 of annular valve member 10, the flow of hydraulic fluid 
through second radial fluid bypass port 69 is restricted thereby slowing 
mandrel 14 for positioning within interior bore 59 of annular valve member 
10 in preparation for another jarring cycle. 
Referring to FIG. 7, there is provided an annular valve member that is 
functionally the same as the annular valve member illustrated in FIGS. 3 
and 4, with the exception that a different configuration of longitudinal 
fluid bypass channel is provided. A longitudinal fluid bypass channel 67 
is provided that extends through sidewall 52 of annular valve member 10. 
The operation is the same as described with respect to FIGS. 3 and 4. 
Referring to FIG. 5, there is illustrated a further alternative version. In 
order to improve operation enlarged diameter portion 36 of mandrel 14 has 
been modified. Enlarged diameter portion 36 has an exterior surface 72, a 
first end 74 and a second end 76. A first fluid bypass channel 78 is 
positioned in exterior surface 72 adjacent first end 74. A second fluid 
bypass channel 80 is positioned in exterior surface 72 adjacent second end 
76. First fluid bypass channel 78 and second fluid bypass channel 80 help 
define a central stopping position for mandrel 14 within interior bore 59 
of annular valve member 10. First fluid bypass channel 78 is in fluid 
communication with first radial bypass port 68 of annular valve member 10. 
Second fluid bypass channel 80 is in fluid communication with second 
radial bypass port 69 of annular valve member 10. When enlarged diameter 
portion 36 of mandrel 14 is entering interior bore 59 of annular valve 
member 10 from portion 38 of fluid chamber 30, hydraulic fluid can 
communicate via first fluid bypass channel 78 with first radial bypass 
port 68 as enlarged diameter portion 36 of mandrel 14 is pushed into 
annular valve member 10. Similarly, when enlarged diameter portion 36 of 
mandrel 14 is entering interior bore 59 of annular valve member 10 from 
portion 40 of fluid chamber 30, hydraulic fluid can communicate via second 
fluid bypass channel 80 with second radial bypass port 69 as enlarged 
diameter portion 36 is pushed into annular valve member 10. A sealing face 
55 extends from each of first end 54 and second end 56 of annular valve 
member 10. A plurality of longitudinal fluid bypass channels 66 and a 
plurality of longitudinal fluid bypass channels 82 are provided, all of 
which extend longitudinally between first end 54 and second end 56 of 
valve member. Longitudinal fluid bypass channels 82 are positioned 
intermediate sealing face 55 and interior surface 58 of valve member 10. 
When a force is exerted upon mandrel 14 to push enlarged diameter portion 
36 of mandrel 14 into interior bore 59 of annular valve member 10, annular 
valve member is pushed against one of projecting shoulders 62 or 64. This 
blocks the flow of fluids through longitudinal fluid bypass channels 66. 
The positioning of sealing face 55 is such that shoulders 62 and 64 do not 
block longitudinal fluid bypass channels 82. It will, therefore, be 
understood that fluid is always able to flow through longitudinal bypass 
channels 82. A metering device 84 is disposed in longitudinal fluid bypass 
passages 82 to meter the flow of hydraulic fluid. The time delay between 
the exertion of a force upon drilling jar 12 and the jarring impact 
resulting from enlarged diameter portion 36 of mandrel 14 moving out of 
interior bore 59 of annular valve member 10, is a function of the pressure 
and volume of hydraulic fluid flowing through longitudinal fluid bypass 
passage 82. The purpose of utilizing metering device 84 is to control the 
time delay and make such time delay predictable. 
FIG. 6 is illustrated in order to illustrated how these various teachings 
can be combined with a single radial bypass port. A single radial bypass 
port 68 is provided for each longitudinal fluid bypass channel 66. Single 
radial bypass port 68 is substantially centrally positioned intermediate 
first end 54 and second end 56 of annular valve member 10. As with the 
embodiment illustrated in FIG. 5, enlarged diameter portion 36 of mandrel 
14 has first fluid bypass channel 78 and second fluid bypass channel 80 to 
help define a central position stopping position for mandrel 14 within 
interior bore 59 of annular valve member 10. Annular valve member 10 has a 
slightly stepped down surface 86 on interior surface 58 in the vicinity of 
radial fluid bypass port 68. Stepped down surface 86 assists in central 
positioning using a single radial fluid bypass port 68. Each longitudinal 
fluid bypass passage 82 is also provided with a radial fluid bypass port 
88. Metering devices 90 and 92 are placed at either end of longitudinal 
fluid bypass passage 82 to meter the flow and control the resulting time 
delay prior to jarring impact. A filter 94 is disposed in longitudinal 
bypass passage 82 for the purpose of filtering contaminants from the flow 
of hydraulic fluid. 
It will be apparent to one skilled in the art that modifications may be 
made to the illustrated embodiment without departing from the spirit and 
scope of the invention as hereinafter defined in the claims.