U.S. patent number 3,853,187 [Application Number 05/440,500] was granted by the patent office on 1974-12-10 for duplex hydraulic-mechanical jar tool.
Invention is credited to Jim L. Downen, Wayne N. Sutliff.
United States Patent |
3,853,187 |
Sutliff , et al. |
December 10, 1974 |
DUPLEX HYDRAULIC-MECHANICAL JAR TOOL
Abstract
This tool embodies in a single structure comprising inner and
outer telescopically related tubular elements confining a body of
operating liquid, a hydraulically retarded up-blow jar, actuated by
placing a lifting strain on the drill string, and a simple
mechanically retarded down-blow jar actuated optionally be
effecting a controlled downward pressure of the drill string on the
jar. The operation of the two jar mechanisms are accomplished
respectively by upward movement of the outer element in an upper
portion of the range of vertical movement between said elements and
by a downward movement of said outer element through a lower
portion of said range of vertical movement. A clearly cognizable
signal is provided for the driller to indicate to him the arrival
of said outer element in the starting position at which the driller
may elect which type of jarring blow he desires to produce in the
immediately following operation of the duplex jar of the
invention.
Inventors: |
Sutliff; Wayne N. (Bakersville,
CA), Downen; Jim L. (Bakersville, CA) |
Family
ID: |
23748997 |
Appl.
No.: |
05/440,500 |
Filed: |
February 7, 1974 |
Current U.S.
Class: |
175/297;
175/304 |
Current CPC
Class: |
E21B
31/1135 (20130101); E21B 31/107 (20130101) |
Current International
Class: |
E21B
31/107 (20060101); E21B 31/00 (20060101); E21B
31/113 (20060101); E21b 001/10 () |
Field of
Search: |
;175/293,296,297,299,300,302,304,306 ;166/178 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Brown; David H.
Claims
The claims are:
1. In a duplex hydraulic-mechanical jar tool, the combination
of:
inner and outer telescopically related tubular elements;
means for connecting one of said elements to a drill string;
means for connecting the other element to an object to be jarred,
referred to herein as a "fish", telescopically overlapping portions
of said elements providing an annular chamber for confining an
operating liquid;
an annular packer supported on one element and slidably engaging
the other element to close one end of said chamber;
an annular floating packer disposed between and slidably engaging
both of said elements to close the other end of said chamber;
a relatively short piston extending radially outwardly from said
inner element into said chamber;
a relatively short cylinder provided inwardly on said outer element
in which cylinder said piston slidably fits to effect a dash pot
retarding action on telescopic movement between said elements when
said piston and cylinder are in conjunction;
the inner surface of said outer element being relieved in areas
immediately above and below the zone of said cylinder, thereby
releasing said elements from said dash pot retarding action when
said piston and cylinder are out of conjunction;
said cylinder, when in conjunction with said piston, dividing said
chamber into a low pressure section, adjacent to and containing
said floating packer and a high pressure section adjacent said
first mentioned packer;
two pairs of impact shoulders provided on said elements which come
respectively into axial abutting engagement when opposite ends of
the entire range of relative telescopic movement between said
elements are reached,
said tool having an optional operation starting position wherein
said cylinder has just passed out of conjunction with said piston
and entered said high pressure chamber section; and
annular cam responsive spring resistance means provided on said
elements in said low pressure chamber section and operative
temporarily to halt further movement of said cylinder into said
high pressure chamber section, until a predetermined heavy downward
pressure has been applied through said drill string to said spring
resistance means to cause the latter to suddenly release and thus
produce a snap action downward jar operation,
an upward snap action jar operation being optionally automatically
accomplished, starting with the tool in said starting position, by
imposing and holding an upward strain of a predetermined value on
said drill string.
2. A combination as recited in claim 1 wherein
said piston makes a substantially liquid tight peripheral fit with
said cylinder when said piston and cylinder are in conjunction,
said piston being provided with an axial hole allowing for the
escape of operating liquid past said piston during the tensioning
of said drill string;
a pin occupying said hole loosely to determine the rate of escape
of said liquid, and
means for locking said pin in said hole yet readily permitting
replacement of said pin with another differing in diameter to vary
the rate of escape of said liquid.
3. A combination as recited in claim 1 wherein said spring
resistance means comprises:
a split tubular head co-axially spaced outwardly from said inner
element and mounted at its lower end on said element, said head
thus providing an annular series of circumferentially spaced
radially flexible arms bearing at their upper ends outwardly,
downwardly sloping cam faces, and
a ring means having an inwardly-upwardly sloping cam face and fixed
on said outer element to concentrically overly said cam faces of
said arms and be closely juxtaposed therewith when said tool is in
starting position.
4. A combination as recited in claim 3 wherein
the angles of said cam faces on said head and said cam ring are
approximately 20.degree. with horizontal.
5. A combination as recited in claim 1 wherein
a lower end portion of said inner element comprises a male spline
sub in which are integrally united a central male spline section
and upper and lower annular head sections the external diameters of
which head sections substantially exceed that of said male spline
section;
said head sections having provided respectively thereon opposed
upper and lower anvil impact faces; and wherein
a lower end portion of said outer element comprises a
longitudinally split female spline sub including two longitudinally
separate halves which fit together on said male spline section to
provide matching female splines;
ring means encircling said male spline sub and axially shiftable
over the lower end of said assembled split female spline sub; and
tapered pin thread means provided on an upper end portion of said
female spline sub, there being matching threaded box means on the
adjacent end portion of said outer element into which said tapered
pin thread means screws to complete the assembly of said split
female spline sub on said integral male spline sub.
6. In a duplex hydraulic-mechanical jar tool, the combination
of:
inner and outer telescopically related tubular elements;
means for connecting one of said elements to a drill string;
means for connecting the other element to an object to be jarred,
referred to herein as a "fish;"
longitudinally spaced seal means forming a chamber between said
elements for confining a body of operating liquid;
dash pot valve means temporarily restricting flow of said liquid
lengthwise in said chamber under a heavy strain imposed on said
drill string, then subsequently permitting said flow to produce an
upward snap action jarring blow on said fish;
annular cam responsive spring resistance means provided on said
elements and operative to temporarily halt telescopic contraction
of said elements caused by lowering said drill string, following
said blow, until sufficient pressure has built up to produce a
downward snap action jarring blow; and
a spline unit at one end of said tool including an integral male
spline sub having heavy external annular heads at its opposite
ends, said sub comprising a portion of said inner tubular
element,
a female spline sub, split lengthwise and assembled broadside on
said male spline sub and united when so assembled with said outer
tubular element; and
two pairs of movement limiting annular impact faces, one face of
each pair being provided by an end of said female spline sub and
the other face of said pair being provided by an end face of the
annular male spline head located in juxtaposed relation with said
first face of said pair.
7. In a deep well jar tool, the combination of:
inner and outer telescopically related tubular elements;
means for connecting one of said elements to a drill string;
means for connecting the other element to an object to be jarred,
referred to herein as a "fish;"
means between said elements operating to restrain free telescopic
movement between said elements in a given direction responsive to a
strain imposed by said drill string for a relatively short distance
and then permitting free movement between said elements;
an integral male spline sub having heavy external annular heads at
its opposite ends, said sub comprising a portion of said inner
tubular element;
a female spline sub, split lengthwise and assembled broadside on
said male spline sub, an upper end portion of said female spline
sub being provided with male pin threads;
a relatively thick walled stabilizer sleeve, comprising a lower
portion of said outer tubular element, and provided, at its lower
end, with female box threads matching said male pin threads, the
latter being screwed into said threads of said stabilizer sleeve in
assembling said female spline sub on said male spline sub,
the upper external annular head of said male spline sub making a
sliding fit within said stabilizer sleeve thereby mutually
reinforcing each other in all operating positions of the tool;
and
means providing hammer and anvil impact faces on said spline stubs
which are brought into collision, when said restraint is relaxed,
to transmit a snap action jarring blow to said fish upon the
termination of said telescopic relative movement between said
tubular elements.
Description
SUMMARY OF THE INVENTION
It is a primary object of the present invention to produce an
improved hydraulic oil well jar of the type covered by U.S. Pat.
No. 2,989,132 issued June 20, 1961 to Jim L. Downen of Bakersfield,
Calif. The Downen jar has a fixed packer at the lower end of the
outer element and a floating packer between the upper ends of said
elements for confining operating liquid in the hydraulic chamber of
the tool. Splines provided within said chamber transmit torque
between said elements and a piston provided on said inner element
makes a close sliding fit with a short cylinder extending inwardly
from the inner surface of the outer element when in conjunction
therewith, a small vertical escape passage being provided in said
piston through which liquid can escape from the high pressure lower
section of the hydraulic chamber into the low pressure upper
section of said chamber while a strain is being placed on the drill
string from which the jar is suspended. As said cylinder rises and
moves out of conjunction with said piston the remaining liquid in
the lower section of said chamber rushes past said piston into the
upper section of the chamber resulting in the delivery of an upward
jarring blow between impacting surfaces provided respectively on
said inner and outer elements.
The return downwardly of the drill string, immediately following
for the purpose of resetting the tool to start another jarring
operation, may be very rapidly accomplished in the Downen jar by
virtue of the fact that while the piston and cylinder are in
conjunction in this return movement, a vacuum is formed in the
lower high pressure section of the hydraulic chamber which prevents
doing any damage to the jar thus permitting the driller to effect
what is known as a spudding operation in which the drill string is
rammed downwardly in resetting the jar until the jar is completely
collapsed thereby delivering a heavy blow to the fish.
Notwithstanding the merit of the Downen jar and the facility with
which a down blow may thus be delivered to the fish alternately
with the delivery of a snap action blow upwardly to the fish (with
the drill string in tension) the type of blow delivered in the
spudding action is not nearly as effective as the snap action blow
deliverable upwardly by the Downen jar.
It is a further object of the invention to provide a jar of the
general type shown in the Downen patent which will offer the
driller the option of delivering snap action jarring blows
downwardly with the jar as well as upwardly.
It is yet another object of the invention to provide such a jar in
which a clear signal will be given the driller in each jar
resetting operation which will indicate the arrival of the outer
element at a point in its vertical reciprocatory movement relative
to the inner element where the driller has the election of
initiating a snap action jar operation in either an upward or a
downward direction.
It is a yet further object of the invention to provide such a jar
tool in which the lowering of the outer element of the tool is
temporarily but positively retarded at the point where the
restricting cylinder withdraws downwardly from conjunction with the
piston on the inner element, thereby giving notice to the driller
that the jar has been restored to its intermediate or starting
position from which point the driller may exercise with maximum
effectiveness his option of performing with the jar either an
upward snap jarring operation or a downward snap jarring
operation.
Yet another object of the invention is to provide a spline tool
which has a relatively rugged male spline sub and may have the
female spline sub replaceable without removing the tool from a
drill string with which it is assembled.
Yet another object of the invention is to provide in said unit an
internal male spline sub having heavy integral external annular
heads at both its opposite ends, and an axially split female spline
sub assembled broadside on the spline section of the male sub and
united at one end by an overriding ring and at the other by its
screwing into the internally threaded lower end of the outer
tubular element of the jar.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 5 inclusive are vertical half sectional views of
successive portions of a preferred embodiment of the invention
which, taken together, illustrate the parts of the latter disposed
in starting position as when beginning an upward or downward
jarring operation.
FIGS. 6 to 10 inclusive are a set of similar views illustrating the
moment of impact in an upward jarring operation.
FIGS. 11 to 15 inclusive are a set of similar views illustrating
the moment of impact in a downward jarring operation.
FIG. 16 is a side elevational view of the split tubular head of the
mechanical retarding device of the down-jar structure of the
invention.
FIG. 17 is a full cross sectional view taken on the line 17--17 of
FIG. 2 and shows the split head shrinking ring crowning said split
tubular head and the supporting relation of the quadrant-sections
of said head with said ring.
FIG. 18 is a full cross sectional view taken on the line 18--18 of
FIG. 2 and shows details of the annular valve piston of the
invention and its environment.
FIG. 19 is an elevational view partly in section and shown to a
reduced scale of a lower portion of the invention embodying in a
single unit all the elements performing the spline, hammer and
anvil functions of the invention, this view showing said elements
on the process of being assembled.
FIG. 20 is an elevational view of FIG. 19 following the completion
of said assembly.
FIG. 21 is a cross sectional view taken on the line 21--21 of FIG.
20 and illustrating the division of the female spline sub of the
invention into two halves.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring specifically to the drawings, the invention is shown
therein as embodied in a hydraulic oil well jar 25 which includes
an outer tubular element 26 and an inner tubular element 27 which
are telescopically related to each other for relative axial
movement in the operation of the jar. As shown in FIGS. 1 to 5
inclusive the tubular element 26 forms a sleeve which houses the
jar and is internally threaded at its upper end so as to screw onto
an upper jar sub 28 which in turn is adapted to scew onto the lower
pin 29 of a tubular drill string 30 on which the jar 25 is
suspended.
The outer tubular element 26 has an inner bore 31 which slideably
contains therein an upper packing member 32 which is recessed for
holding internal 0-rings 33 and external 0-rings 34. The lower end
of bore 31 terminates with a shoulder 35 located at the upper end
of a counterbore 40. A tripping ring 41 fits within the counterbore
40 against the shoulder 35 and is secured in place by screws 42
which are screwed into suitable tapped holes provided in outer
tubular member 26 and fit into suitable recesses provided in the
periphery of the ring 41. The ring 41 has an inwardly and upwardly
beveled bottom cam face 43 which is preferably ground at an angle
of 20.degree. with horizontal.
The counterbore 40 presents a smooth cylindrical surface in a short
annular area 44 (see FIG. 2) which will be referred to hereinafter
as the "cylinder" of the jar 25. Immediately above and below the
cylinder 44, the counterbore 40 is relieved by vertical channels 45
and 46 for a purpose to be made clear hereinafter. One or more
suitable tapped holes are provided in the outer tubular element 26
of the jar for use in admitting operating liquid thereto, these
holes being closed by filler plugs 47.
The lower end portion 48 of the outer tubular element 26
(hereinafter referred to as the stabilizer sleeve) is secured to
said element by heavy tapered threads 49, the male threads of which
are formed on a heavy annular internal head 50 provided to extend
inwardly from the upper end of said sleeve. Provided on the head 50
to extend inwardly therefrom is a packer 55. Provided in sleeve 48
for a purpose to be made clear hereinafter are rather ample fluid
ports 56 and 57. Stabilizer sleeve 48 has a smooth internal bore 58
and a lower end portion thereof is provided with heavy female
internal threads 59. The lower end of stabilizer sleeve 48 has a
male taper 60 of about 20.degree.. The threads 59 constitute one of
the means for assembly of the two halves 61 and 62 of a female
spline sub 63. When assembled, the two halves 61 and 62 of female
spline sub 63 are brought together face-to-face to form said
complete sub and so as to provide thereon a heavy cylindrical
tubular body 64 which is machined internally to provide three
female splines 65 and is turned down at its upper end to provide an
annular hammer 70 and male threads 71 (matching female threads 59)
and a female taper 72 matching the male taper 60 on stabilizer
sleeve 48. The opposite or lower end of the female spline sub body
64 is turned down to provide a lower annular hammer 73 which also
receives an integral reinforcing ring 74 which is secured in place
in uniting relation with the female spline sub halves 61 and 62 by
cap screws 75, the heads of which are countersunk in said ring. The
assembly of the female spline sub having been thus advanced by the
application to the sub halves of integral reinforcing ring 74 as
above described, the two halves as a unit are then screwed into the
threads 59 provided in the lower end portion of stabilizer sleeve
48 so as to rigidly unite the two sub halves 61 and 62 are shown in
FIG. 20. Further details relating to the mode of assembling female
sub 63 will be made clear hereinafter.
The inner tubular element 27 of the tool 25 comprises upper and
intermediate thin walled sleeves 76 and 77 and a relatively heavy
walled tubular male spline sub 78. The upper sleeve 76 makes a
loose sliding fit upwardly within upper sub 28 when the tool 25 is
in starting position as shown in FIGS. 1-5 inclusive and screws, at
its lower end, into a threaded socket provided therefor and
recessed in the inner face of the upper end of intermediate sleeve
77. The exterior face of sleeve 76 is concentrically spaced from
the bore 31 of outer tubular element 26 so as to slideably confine
the sliding upper packing 32 therebetween. Formed externally on an
upper end portion of intermediate sleeve 77 is an annular head 79
having external threads 80 on which is screwed the annular base 85
of a mechanical tripping device 88 comprising a split tubular head
divided into four inwardly yieldable quadrants 87, each bearing a
quadrant shaped head 88 which normally underlies tripping ring 41
and has a matching face 89 which parallels the cam face 43 of ring
41 as clearly shown in FIG. 2. Each head 88 has at its upper
extremity a guide wall 90 for guiding said head inside of the
tripping ring 41.
A short distance downwardly from the lower end of tripping device
base 85, the external annular head 79 of intermediate sleeve 77 is
turned down to form a shoulder 91 and form a cylindrical surface on
which an annular sleeve piston 92 may snugly fit. The external
annular sleeve head 79 is also recessed to accommodate an O-ring 93
and is threaded to receive a nut 94 for tightly uniting piston 92
with annular head 79.
Beneath the external annular head 79 provided on the intermediate
sleeve 77 of inner tubular element 27, said sleeve is relatively
thin walled so that its external surface 95 is spaced from
counterbore 31 of outer tubular element 26 (see FIG. 3) so as to
slidingly confine the packer 55 mounted upon the internal face of
annular upper internal head 50 on stabilizer sleeve 48.
The annular sleeve piston 92 is also seen in FIG. 2 to make a close
sliding fit with counterbore 40 of external tubular element 26 in
this view which illustrates the invention in its starting position.
Here, the piston 92 is disposed just above the cylinder 44 which is
to stay out of conjunction therewith and entirely opposite the
upper relief grooves 45 formed in counterbore 40 so as to allow a
free passage of operating liquid vertically past piston 92 and past
the cylinder 44 so long as piston 92 remains so positioned.
This piston is provided with a vertical hole 100 which confines a
gauge rod 101 for gauging the amount of free space in said hole
left available for a flow of liquid therethrough and hole 100 is
overlapped slightly at its ends by shoulder 91 and nut 94 so as to
prevent the escape of rod 101 from said hole. Variations in the
rate of travel of the cylinder 44 relative to the piston 92 during
the operation of the jar 25 to effect an upward snap action jarring
blow can be accomplished by selecting a pin 101, in assembling the
tool before using the same, so as to accomplish the desired rate of
travel of the piston 92 during the jarring operation. The external
surface of the piston 92 is also provided with an annular groove
for receiving an O-ring 102 which assures a tight sealing fit
between the periphery of the piston 92 and the cylinder 94 when
these two elements are in conjunction.
The lower end portion of intermediate sleeve 77 is externally
threaded at 103 and provided with an external O-ring 104 to permit
said sleeve to be screwed into and make a sealed connection with an
externally enlarged upper annular head 105 provided on the upper
end of male spline sub 78. This annular head makes a snug sliding
fit with the smooth cylindrical bore 58 formed in stabilizer sleeve
48. These two elements are thus always in reinforcing relationship
throughout the operation of the jar 25 which greatly adds to the
efficiency and operating life of the jar. The sub 78 has another
externally thickened annular head 106 at its lower end, these heads
being integrally united by a relatively thin walled central male
spline section 107 which is milled out externally to provide a
series of three male splines 108.
The lower externally thickened annular head 106 of male spline 78
has provided thereon a threaded tool pin 109 for connecting the
lower end of the jar 25 to a drill collar 110 through which the jar
25 is connected to the fish, recovery of which is being sought.
Attention is now called to the fact that the provision of
externally thickened annular heads 105 and 106 at the upper and
lower ends of the male spline sub 78 provides on one integral
element upper and lower anvil faces 115 and 116. This integration
of these two faces in the male spline sub greatly strengthens the
tool 25 in the vital shock area of the tool. The confining of the
upper annular head 105 of the male spline 78 within the stabilizer
sleeve 48 so that this head is at all times in close sliding
confinement by said sleeve, also powerfully reinforces said male
spline sub in the area in which the maximum shocks are sustained by
the tool.
The features just noted are made possible in the tool 25 by
providing the female spline sub 63 in two halves 61 and 62 by
splitting the female sub lengthwise. It thus becomes unnecessary to
make one end of the male spline sub of small enough diameter to
permit the male spline sub to penetrate axially the bore of the
female spline sub in assembling the tool. The provisison of a
relataively heavy stabilizer sleeve 48 having heavy tapered female
threads 59 in its lower end for threadedly receiving matching male
threads formed on the upper ends of the two halves of the female
spline sub 63, plus coupling together the lower ends of the female
spline sub halves by the integral reinforcing ring 74, provides the
female spline sub with adequate strength to endure the pounding it
must sustain by employing the upper and lower ends of the sub as
hammer faces 70 and 73.
An added dividend derived from the design just described of the
unit shown in FIG. 19, in which is concentrated the spline function
as well as separate pairs of hammer and anvil faces for the
performance of both up as well as down snap action jar operations,
is the facility possessed by the jar 25 of permitting the
replacement of the female spline sub 63 in the jar by a new such
sub without the necessity of removing the jar from the string and
in a relatively short shut down for this service.
OPERATION
An annular chamber 117 is provided between the outer tubular
element 26 and the inner tubular element 27 which is closed at its
lower end by the fixed packer 55 and at its upper end by a sliding
packer 32. One or more plugs 47 are provided for use in the
conventional manner for filling chamber 117 with operating fluid,
which is generally a light lubricating oil, and for withdrawing the
air from this chamber at the time the fluid is delivered thereto.
When the tool 25 is in its normal starting position with the parts
as shown in FIGS. 1-5 inclusive, the entire chamber 117 is filled
with operating liquid. As seen in FIG. 2, the cylinder 44 is out of
conjunction at this time with the piston 92. Lifting the drill
string 30 from this position to bring cylinder 44 into conjunction
with the piston 92 divides the hydraulic chamber 117 into a high
pressure lower section and a low pressure upper section. The upper
section always remains a low pressure area because of the freedom
of the sliding packer 32 to shift vertically in response to any
change in the relative pressures below and above said packer so
that the pressure in the upper section of the hydraulic chamber 117
is always substantially equal to the pressure of the ambient well
fluid in which the tool 25 is operating. The inner tubular element
27 being connected through the drill collar 110 to the fish which
is stuck in the well, elevation of the cylinder 44, bringing this
into conjunction with the piston 92, is achieved by the driller
raising the drill string 30 to tension the same.
With the parts of the tool 25 positioned as shown in FIGS. 1-5
inclusive, the driller has two options open to him in operating
said tool. The first of these is to lift on the drill string 30 to
bring the cylinder 44 into conjunction with the piston 92 which
retards escape of the operating liquid in the high pressure section
of the chamber 117, thus giving an opportunity to build up a
relatively high tension strain on the drill string 30 during the
travel of the cylinder 44 upwardly past the piston 92 and resulting
in an upward snap action jarring operation when the hammer 70
strikes the anvil 115 as shown in FIG. 9.
The location of the respective elements of the jar 25 at the moment
of delivery of an upward snap action jarring blow by the tool 25
are illustrated in FIGS. 6-10 inclusive. Immediately following the
delivery of this upward blow through the operation above described
of the jar 25, the driller lowers the drill string 30 to return the
parts of the jar 25 to their positions shown in FIGS. 1-5
inclusive. This jar has the facility of providing a clear
indication of the arrival of the parts of the jar in this position
by the fact that as this position is reached, the tripping ring 41
comes to rest on top of the mechanical tripping device 86 by the
sloping cam face 43 of said ring engaging the matching sloping
faces 89 provided on the four inwardly yielding quadrants 87 of
said device. These faces are cut approximately on a 20.degree.
angle with horizontal for the express purpose of requiring about
20,000 pounds of pressure on the device 86 before the latter will
react by the quadrants 87 snapping inwardly to allow the ring 41 to
pass downwardly around these quadrants into the position in which
said ring is shown in FIG. 12. The reaction of the rig to the
resistance to downward travel of the outer tubular element 28
provides a readily discernable signal to the driller at the top of
the well indicating to him that the parts of the jar 25 are in the
starting position shown in FIGS. 1-5 inclusive. The driller is thus
able to exercise without hesitation at this point the option as to
whether he is going to continue lowering the drill string 30 beyond
the starting position so as to effect a down snap action jarring
operation or whether he is going to repeat the upward snap action
jarring operation which he has just completed. Obviously, if he
desires to repeat the upward jarring operation, it is important
that he be advised through this signal of the arrival of the parts
of the jar at their starting position so that he can exercise the
option given him by this signal, thereby maintaining close control
of the operation of the jar in his selection of the type of jarring
operation in each instance which he has programmed accomplishing
with the jar 25.
Should the driller elect a repetition of the upward jarring
operation, each of these operations would start therefore with the
parts of the jar as shown in FIGS. 1-5 and constitute a repetition
of the upward jarring operation just described. Whenever the
driller elects to follow the arrival of the parts of the jar
downward in their starting position as shown in FIGS. 1-5
inclusive, to accomplish a downward snap action jarring operation,
the driller merely continues his application of downward pressure
to the drill string 30 on the outer tubular element 28 of the jar
after the ring 41 is set down on the sloping faces 89 of the
inwardly yieldable quadrants 87 of the tripping device 86. With the
weight of the drill string 30 often being in the neighborhood of
100,000 pounds it takes only a short relaxation of the rig, while
lowering the drill string 30, to apply 10 tons of pressure to the
tripping device 86. When this pressure is reached however, a snap
action downward jarring operation takes place in which the annular
lower hammer face 73 of the female spline sub 63 is snapped
downwardly from the position in which it is shown in FIG. 4 into
violent impact with the annular hammer 116 as shown in FIG. 15.
It is to be noted that in the starting position of the parts of the
jar 25 shown in FIGS. 1-5 inclusive and particularly in FIG. 2, the
cylinder 44 provided on the outer tubular element 26 has already
passed downwardly beneath the piston 92 so that there is no or very
little resistance incurred in the passage of operating fluid past
said piston and cylinder during the downward snap action jarring
operation just described. At the start of said operation, the
piston 92 and cylinder 44 are relatively positioned as shown in
FIG. 2 and at the conclusion of that jarring operation they are
still further separated as shown in FIGS. 12 and 13.
Following the operation of the jar 25 to effect a downward snap
action jarring blow as shown in FIGS. 11-15 inclusive, the driller
immediately operates his rig to lift the drill string 30 the short
distance required to restore the parts of the jar to the position
in which these are shown in FIGS. 1-5 inclusive. In this reaction
of the parts of the jar to starting position, the driller is given
a clear signal of the arrival of the parts of the jar at this
position by the rapid increase in the strain imposed on continuing
the lifting of said drill string, by the annular cylinder 44 coming
into conjunction with the piston 92 thereby greatly increasing the
force required to continue lifting on the drill string. This
constitutes a signal to the driller that the parts of the jar have
reached their starting position shown in FIGS. 1-5 and, in case the
driller wishes to exercise the option thus given him of repeating
the downward snap action jarring blow just performed, he can
readily do this by reversing his rig and starting to lower the
drill string 30.
It is to be noted that when a downward jarring operation is
performed with the jar 25, the ring 41, after being effective in
springing the yielding quadrants 87 inwardly so that these no
longer resist the downward movement of the outer tubular element
25, this ring slides downwardly past the quadrant shaped heads 88
and at the conclusion of delivery of the downward jarring blow
being accomplished, the ring 41 has slid downwardly to a point
where it is just above the annular base 85 of the tripping device
86. During the restoration of the parts of the jar 25 to their
starting position, the upward movement of the outer tubular element
26 causes the ring 41 to slide up over and constrict the inwardly
yielding quadrants 87. Upon ring 41 reaching its starting position
shown in FIG. 12, said quadrant heads 88 will spring back outwardly
under the ring 41 in readiness to initiate another downward snap
action jarring operation.
* * * * *