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Патент USA US3039554

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Ju?e 19, 1962
C J. MCWHORTER
3,039,544
METHOD OF AÑD MEANS FOR DETERMINING THE
INCLINATION 0F WELL. PIPES
Filed June 25, 1959
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June' 19, 1962
c. J. MowHoRTER
3,039,544
METHOD OF AND MEANS FOR DETERMINING THE
INCLINATION oF WELL PIPEs
2 Sheets-Sheet 2
Filed June 25, 1959
C‘u//en d M C W/mr fer
INVENToR.
BY
Afro/Mfr l
3,039,544
„
United States Patent()
1
3,039,544
METHOD 0F AND MEANS FOR DETERMINING
THE INCLINATION 0F WELL PÍPES
Cullen J. McWhorter, Houston, Tex., assignor to Houston
Oil Field Material Company, luc., Houston, Tex., a
corporation of Delaware
Filed June 25, 1959, Ser. No. 822,903
10 Claims. (Cl. 175-45)
This invention relates to `a method of and apparatus for
logging wells, and more particularly to a method of deter~
mining variations in the inclination `of a well pipe for the
purpose of locating the point at which the pipe is stuck
in a. Well, and to an improved inclino-meter for use in
carrying out such a method.
In the drilling and operation of wells, such as oil and
gas wells, it is customary to produce a Well bore by the use
of a tubular drill string, having at its lower end a drill
” ICC
Patented June 19, 1962
2
readings in totally free pipe to zero at some point well
below the top of caved in formations or settlings that are
binding the pipe. This is due to the fact that torque or
tension is transmitted through the top portion of the loose
material around the pipe and a certain amount of “free
travel” is established in this loose formation by the usual
working of the pipe by the operator in lan eifort to free
the pipe. This “free travel” is often misleading as to
the -true degree of stuckness of the pipe and often results
in the pipe being backed olf or cut at a depth well below
the top of the formation that is binding it. When this
happens it is often impossible to pull the freed portion of
pipe from the bore hole necessitating a 4second cut or
“back ofi,” or, if the freed portion can be pulled out of
the binding material the top portion of the iis-h may be
filled by this material falling into it and future iishing
operations may be impeded.
In the inclinometer method, described more fully here
inafter, this condition of stress and strain transmitted
which is rotated with the string, the string being usually
through the loose formation is not so much a factor.
of somewhat smaller external diameter than the diameter 20 Changes in tension and in the amount of torque present in
of the bore, and drilling Amud being circulated through the
free pipe will cause the pipe to repose in the bore hole in
string and through the bore outside of the string during
different conditions of convolutions =and/ or spirals. This
lthe drilling operation to lubricate the drill `and to carry
is especially true if the free pipe in one condition is under
away the cuttings formed thereby. The bore of a well
-a considerable tension as shown in FIGURE 1A, and an
produced in this manner may deviate substantially from 25 other condition of being relaxed with weight of upper
the vertical yand in wells of substantial depth such devia
sections bearing down on it as shown in FIGURE 2A.
tion frequently takes place in different directions so that
Normally, under tension the pipe would reside on the low
the bore is curved at various locations. Under some cir
side of the bore hole (all -bore holes have some deviation
cumstances, such as when the drilling takes place in in
from a true vertical) and generally conform to the con
30
clined formations, or 'when alternately soft and hard
tour of this low side. When under compression, the pipe
formations are encountered, the drill may be deflected in
would «bow out at intervals from this low side and rest
a manner to produce relatively sharp curves or bends,
sometimes referred to ‘as “dog legs.”
ln carrying out well drilling or other operations in wells
the drill stern or other well -pipe lwill follow generally the
curvature or inclination of the bore and when the well
pipe is substantially smaller in diameter than the bore,
which is usually the case, the pipe engages the wall of the
bore at various locations throughout the length of the
bore, so that the inclination of the pipe v‘aries and is dif
approximately against the opposite wall of the bore hole.
This produces a series of convolutions or curves in the
pipe 4that causes the pipe »at one point to have less inclina
tion and at another point to have more inclination than
it had when under tension, lf there is loose formation
surrounding the pipe it cannot have the freedom of side
to side movement to produce changes in inclination be
cause it would require a very considerable force to produce
side movement of the pipe against the restraining forma
ferent from the inclination of the bore at some locations
-tion Eand this force is not sufiicient since it is derived
and may even assume a somewhat spiral shape.
from the weight of upper sections applied at the relatively
It is often desirable to determine the inclination of the
small angles in the pipe in relation to the bore hole.
well bore, `or of the drill stem or other pipe therein, such
Thus, if an inclinometer log is run of a section of pipe,
45
`as the well casing or tubing, especially for the purpose of
part of which is free and part stuck, under conditions of
locating a dog leg or other irregularity in the bore likely
tension and compression, there will be a sharp change be
to interfere with the insertion or withdrawal of the well
tween the character of the two logs at the point Where ’the
pipe, or to locate the point at which the drill stem has
binding formation begins, which is the desirable point at
become stuck in the Well due -to caving of the formation,
50 which to attempt a `cut or “back o'if” of the pipe. This
settling of the drilling mud, or'from other causes.
Heretofore, in attempting to locate the point at which
a well pipe should be disconnected or cut oif, when such
change in character of the inclinometer logs in f-ree pipe
a pipe has become Stuck in a well, it has been customary
to make use of instruments of the strain gage type, which
a spi-ral condition with resultant changes in inclination
can be induced by a change in the amount of torque ap
plied since twisting a string of pipe will cause it to assume
different points.
may be lowered into the well pipe and held stationary 55 at The
inclinometer instrument may be used to make read
therein »while the stress or strain on the pipe is varied to
ings at selected points like instruments currently in use,
indicate by deformation of the pipe whether the pipe at a
but the amount of change in deviation will vary from
particular location is free or stuck. By this method it is
point to point. Any reading, however, will indicate that
possible to locate within rough limits the por-tion of
the pipe is free and readings can be checked at la slightly
the pipe which is stuck and the portion which is free by 60 different depth to avoid points where the inclination of
relatively few readings, but this method has the disad
the pipe does not change appreciably between conditions
vantage that it is necessary to make a separate test at
of tension or compression.
each of a large number of longitudinally spaced locations
The present invention has for an important object the
in order to accurately locate the point at which the pipe
is stuck.
The current procedure in determining the point at which
a string of pipe may be freed is to take la series of read
ings in the pipe at lower and lower levels until a point is
found where no readings can be obtained which is indica
65 overcoming of the above disadvantages of the methods
heretofore employed in logging the variations and in
clinations of a well bore or of a pipe located in such a
bore, by the use of an improved method of and means
for continuously measuring the inclination of the bore or
tive of the fact that the stress or strain at this point can 70 pipe throughout its length.
not be varied due to the stuck condiion of pipe above his
Another object of the invention is to provide a method
point.v Generally these readings will diminish from full
3
3,039,544
for accurately locating the stuck portion of a pipe which
is stuck in a well bore.
A further object of the invention is to provide an in
clinometer of improved construction and sensitivity, for
use in measuring very small variations in inclination from
the vertical.
Another object of the invention is the provision of an
inclinometer which is electrically operated and by which
a continuous record or log of the changes in inclination of
a well bore or of a pipe located therein may be made.
A further object of the invention is to provide a method
of accurately locating the stuck portion of a string of
pipe stuck in a well bore which comprises making a con
tinuous record of the amount of deviation of the pipe
from the vertical throughout a substantial length of the
pipe including a portion of the pipe at the location where
4
FIGURE 3 is a fragmentary, vertical, central, crosssectional View, on a somewhat enlarged scale, of a por
tion of a well bore, showing a well pipe therein with the
inclinometer of the invention in an operable position in
the pipe, the pipe being shown partly broken away and
partly in cross~section;
FIGURE 3A is a fragmentary, front elevational view on
a somewhat enlarged scale of a portion of a chart showing
a typical recording indicating the variations of the in
clinometer of the invention as the inclinometer passes
downwardly through the pipe, illustrated in FIGURE 3;
and
FIGURE 4 is a vertical, central, cross~sectional view, on
an enlarged scale, showing details of construction of the
operating elements of the inclincmeter of the invention.
Referring now to the drawings in greater detail, the
the pipe is stuck, applying a force to the pipe to change the
method and apparatus of the invention are particularly
inclination of the free portion of the pipe, making a con«
useful in connection with the drilling and operation of
tinuous record of the deviation of the pipe from the vertical
wells, such as oil wells, the bore of such a well being
throughout said length of the pipe, and comparing the 20 indicated
at B, which bore may be provided with a casing
two recordings to locate a region in the pipe where the in
or liner C, extending downwardly from its upper end
clination of the pipe remains substantially unchanged.
throughout a portion of the bore, and having an inner pipe
Another object of the invention is to provide a method
or tubing T, of substantially smaller diameter than the
for locating the stuck portion of a string of pipe stuck
bore, which extends below the lower end of the casing C
in a well bore which comprises making a continuous rec
and which is illustrated as being stuck in the well bore, as
ord of the variation in inclination throughout the length
by
the caving of the surrounding formation as shown at F,
of the pipe including a portion of the pipe at the location
or the accumulation of drilling mud, sand, or the like, in
where the pipe is stuck, while the pipe is in a relaxed con
the bore about the exterior of the pipe.
dition, exerting a pull on the upper end of the pipe to
Under these conditions, it is desirable to accurately
change the inclination of the pipe throughout the free 30 locate
the zone in the well bore in which the pipe is stuck,
portion of the pipe, making a continuous record of the
so that the pipe may be cut or disconnected at a point
variation in the inclination of the pipe throughout said
above the stuck portion to permit the portion above to be
length of the pipe, while maintaining the pulling force on
removed from the bore and the subsequent carrying out of
the upper end of the pipe, and comparing the two record
washover operations by which the stuck portion of the
ings to locate the portion of the pipe in which the in
pipe may be recovered from the well.
clination remains substantially unchanged.
The apparatus by which the method of the invention is
A further object of the invention is to provide a method
carried out comprises an inclinometer enclosed in a suit
of placing a well pipe in condition to be disconnected
able housing 10, connected at its upper end to the lower
which includes determining the variations in inclination
end of a cable l2, by which the inclinometer may be low
of the pipe throughout a portion of the length of the pipe 40 ered
into the well pipe, and which is operated by suitable
to determine the condition of stress in the pipe in said por
winding
mechanism 14 rotatably mounted in any con
tion and applying a force to the pipe to place the pipe in
venient manner above the upper end of the well. The
a desired condition of stress.
A still further object of the invention is to provide
an inclinometer of simple design and rugged construction
whose sensitivity and accuracy is substantially unaifected
by the extreme conditions of hard usage to which instru
ments of those characteristics are likely to be subjected
when used in well logging operations.
The above and other objects and advantages of the
invention may best be understood from the following de
tailed description constituting a specification of the same,
and considered in conjunction with the annexed drawings
wherein
FIG. l is a fragmentary, partly diagrammatic view, il
lustrating the method and apparatus of the invention show
ing the inclinometer of the invention partly broken away
and partly in cross-section located in the well pipe in a
well bore, the recording mechanism employed therewith
being shown diagrammatically;
FIGURE lA is a fragmentary, vertical, central, cross
sectional view on a reduced scale, of a portion of a well
bore showing a well pipe positioned therein, and showing
cable 12 is of the conductor line type having one or more
suitably insulated conductors therein by which electric
current may be supplied to the inclinometer and through
which current may iiow to suitable recording mechanism
by which a continuous record of variations in the inclina
tion of the well pipe may be recorded.
The inclinometer mechanism of the invention, as best
seen in FIGURES l and 4 includes an elongated tubular
element 16 located in the housing 19 and whose upper
end 18 is closed and whose lower end extends into the
upper end of an open receptacle 20 supported in the
‘bottom of the housing. The lower end of the tube 16
opens into the interior of the receptacle ‘20 in spaced
relation to the bottom of the receptacle and the tube
and receptacle contain a column of `a heavy liquid, pref
erably mercury, whose upper end is located rat a prede
termined level 22 in the tube caused by the pressure of
60 air in the housing acting Vupon the surface of the liquid
in the receptacle. The housing 10 may be completely
closed Iand `sealed to maintain the pressure in the housing
at any desired pressure and to prevent variations in the
a location at which the pipe is stuck in the well, the pipe
being shown in the position which it occupies during one 65 pressure of the external atmosphere from causing changes
in the effective length o-f the column of liquid. An in
stage of the method of the invention;
duct-ance coil 24 surrounds the tube near its upper end
FIGURE 2 is a fragmentary front elevational View of a
and within the tube a core 26 of magnetic material such
portion of a chart showing a typical form of the contin
as “ferrite” or other suitable material having a high mag
_uous record made by the method and apparatus of the
netic permeability is movably positioned in contact with
invention, and indicating the variation in the inclination 70 the upper end of the mercury column in position for
from the vertical of a well pipe in a well bore;
longitudinal movement in the tube relative to the induc
FIGURE 2A is a view similar to that of FIGURE lA,
tance
or tank coil 24 to vary the inductive eñïect of this
showing the typical variation in the inclination of a well
coil
in
an oscillator circuit in accordance with the longi
pipe corresponding to the recording of FIGURE 2 dur
tudinal movement of the inductor in the tube. The coil
ing another stage of the method of the invention.
75 24 is connected as by means of `conductors 28 into an
6
electrical circuit including an oscillator 30 of conven
tional construction, located in the upper end of the hous
ing Il) and is in turn connected by the conductors of the
cable 12 to the recorder mechanism at the surface.
The recorder mechanism may be of usual construction
including a coupling transformer 32, having a primary
winding 34 of low impedance connected in circuit with
the oscillator 3ft, through the conductors of the cable 12,
rection of such deviation, will produce a decrease in the
frequency of the current from the oscillator ‘30 due to
movement of core 26 toward the coil 24 caused by a
change in the effective length of the mercury column,
causing the pen of the recorder to move laterally on
the chart 44 to indicate such change of inclination.
It will be apparent that by varying the impedance in
the electrical circuit between the receiver 40 and the
recorder 42, the instrument may be calibrated to produce
and with a suitable source of direct current supply, such
more or less `lateral movement of the pen 46 upon the
as that indicated at 36, and having »a secondary winding 10 occurrence of a predetermined amount of change in the
33 which is connected in circuit with a receiver 40 Whose
inclination of the inclinometer. For example, the ñrst
output is supplied to an electrical recorder 42 of usual
calibration maybe such as to produce a full scale de
construction, which includes a chart or tape 44 upon
flection of the recorder for a deviation of the inclinom~
which the record is made.
'
eter of l degree. Subsequent calibrations may be made
The oscillator 30 is constructed to generate an »alter
requiring a 2 degree inclination in the inclinometer'to pro
nating current at a frequency which is determined by the
duce full scale deflection of the recorder or the instru
size of the capacitors in the oscillator and the inductance
ment may be calibrated to require 3 or 4 degrees or
of the tank coil 24 when direct current is supplied to the
more inclination of the inclinometer to produce full scale
oscillator from the source 36 through the primary wind
deflection of the recorder to adjust the recorder to record
ing 34 of the transformer 32 and through the conductors 20 the maximum deviation likely to be encountered in a
of the cable 12. The frequency of the current generated
well bore.
by the oscillator may be of the `order of 40 kilocycles
lf this inclinometer is run in a -bore hole or through
and this alternating current is transmitted through the
a string of pipe in a bore hole it is possible to record
cable 12 to the coupling transformer 32 and through the
25 deviation from the vertical as a function of depth as in
_ transformer and bypass condensers, not shown, to ground
land thus back to the oscillator. The alternating cur
rent from the oscillator is superimposed on the direct
current and generates an alternating current of the same
frequency in the secondary 38 of the coupling trans
former. The direct current passing through the primary
has no effect on the secondary, So that -a separation of
the alternating current from the direct current is effected
by the coupling transformer in the receiver 40, shown in
FIGURE l. There is another oscillator (not shown)
provided in the receiver whose function is to provide a
reference frequency which may be controlled by the
operator. This reference frequency of oscillation may
be set to equal »the frequency being generated by the in
strument in the well. The receiver also includes a fre
quency mixing circuit which produces no output as long
as the frequency of the oscillator 30 and the frequency
of the oscillator in the receiver lare equal, but when
one of these frequencies changes, there is generated in
the mixer device an alternating potential whose frequency
is the difference between the two frequencies being fed
dicated in FIGURE 2. Such a recording will show sud
den changes in deviation in a bore hole, commonly called
“dog legs,” which might be missed by a directional sur
Vey made at intervals in the bore hole.
The change in the inclination of pipe as before de
30
scribed is necessarily small because of the relatively close
proximity of the walls of the bore hole to the pipe. This
condition will vary as will the forces causing changes in
inclination but in general it may be stated that the change
35 will be of the order of l degree to 2 degrees or less. In
some instances of heavy sections such as drill collars, the
change may be as small as one-third of one degree. It is
apparent, therefore, that an inclinometer must be sensitive
and have a high degree of resolution to successfully re
40 cord such changes in deviation. As before mentioned the
most sensitive calibration sitting should produce a full
scale deflection of the recorder for a change of only one
degree. On such a scale, 1/3 of one degree change (or 20
minutes) will appear as 1/3 of full scale which is easily
discer'nable.
At the point where a string of pipe is stuck, it may be
found that the deviation from the vertical is relatively
.beat frequency is amplified in the receiver and fed through
large as for example 9 degrees. If the sensitivity cali
a rectifier network in the receiver which produces a di
bration step is set high enough for example l0 degrees for
rect current output from the receiver whose magnitude
a full scale deflection of the recorder, then 9 degrees will
50
is directly proportional to the >beat frequency. The out
appear on the chart on the extreme right, and if the
put from the receiver is fed directly into the recorder 42,
variations in deviation of the pipe were only 1A of one de
shown in FIGURE l, which produces a record on the
gree, then the changes which can be recorded in inclinome
chart 44 indicating variations which take .place in the
ter logs between the conditions of tension and compres
frequency of the current from the oscillator ‘30. Thus, as
sion will appear small in comparison with the full scale of
55
long as the frequencies of the currents from the oscillator
the log.
30 and those from the oscillator in the receiver remain
To offset this condition, the beat frequency oscillator
into the device. rfhis is known as a beat frequency. This
the same, the record on the chart 44 will be a straight line,
in the receiver may be adjusted in a direction to reduce
but upon the occurrence of a Variation in the frequency
the beat frequency an amount equivalent to say 8 degrees:
of the current from the oscillator 3€), the direction of the
then a reading of 9 degrees will appear on the log in the
line on the chart will be changed accordingly, indicating 60 same place as a l degree reading would before. This will
a deviation of the inclinometer from the vertical.
create an artificial zero and then by using a sensitivity step
In practice, the inclinometer is suspended vertically
of say 2 degrees for full scale, it is possible to record dif
before lowering it into the well and the receiver 4t)` is
ferential inclinometer logs to reveal positively small
adjusted to produce Zero beat frequency or zero output,
changes in inclination even though the total inclination of
65
'and the recorder, likewise is adjusted to indicate zero,
the string were large.
so that the pen 46 of the recorder, shown in FIGURE l,
The inherent sensitivity of this device may be seen from
will make a straight line longitudinally moving on the
the fact that the inductance of a tank coil of an oscillator
chart 44. In this position of the inclinometer, the effec
whose natural frequency is in the order of 40 kc. has a
tive length of the mercury column supporting the core 26
very profound effect on the oscillator. In other words,
will be shortest, and the core will be at its farthest point 70 changes in the position of a tuning inductance within the
of movement relative to the tank coil 24; causing the
tank coil will sharply change the natural frequency of
inductance of the tank coil to be at a minimum and the
oscillation. Specifically, a change of only .O01 inch either
frequency of the oscillator 3@ to be at a maximum.
in or out of the tank coil (shown in FIGURE 4) by the
In this condition of the apparatus, any variation of
inductor will shift the frequency of oscillation by as much
the inclinometer from the vertical, regardless of the di 75
3,039,544
as 30 cycles. If an inclinometer tube 30 inches long is
mined by a single pass of the inclinometer, either with
inclined l degree from the vertical, the length of the
the pipe in a relaxed condition, or under
duced by an upward pull on the string.
seen that the amount of upward pull
string need not be suñicient to place the
column of 'mercury will be increased .0045 inch, which
will cause the inductor t'o move this amount into the
tank coil and will produce 4.5 times 30, or 135 cycles
change. This will be more than 2 cycles change for each
the tension pro
It will also be
exerted on the
entire length of
the free portion of the pipe in tension, since the method
minute of change in deviation and easily falls within the
previously described minimum requirement of 1 degree
ofthe invention does not depend upon the tension or com
pression to which the pipe is subjected, but only upon the
change in inclination resulting from a change in the down~
for a full scale deliection of the recording equipment.
The inciinometer instrument will be sensitive to changes l0 ward force exerted on the pipe.
in the internal diameter of the pipe. In FIGURE 3, the
rThe invention is disclosed herein connection with a
instrument moving down inside an inclined section of pipe
certain specific embodiment of the apparatus employed
will be disposed on the low side and the nose of the instru
and procedure in carrying out the method, but it will be
ment will be deñected toward the center of the pipe on
reaching an internal reduction in diameter, such as may be
caused by a coupling 50, thus causing a momentary in
crease in `deviation and a kick or jog on the inclinometer
log away from Zero. The reverse will happen as the in
strument passes through such an internal reduction back
into the original pipe size, as indicated at 54. Thus inter
nal upset points will show as a kick, followed by re
versal. Reduction in pipe size will show as an outward
curvature of the line of the recording and an increase in
pipe size will show as an inward curvature of the line.
The inclinometer instrument may be used to find the
condition at which tension and compression are equal at
a given point in a string of pipe above the stuck point. If
the instrument is positioned at a point where it had been
observed (from logs or static readings) that a change in
inclination occurred between tension and compression in 30
the pipe and starting with a relaxed condition (compres~
sion) to slowly raise the string of pipe at the surface until
a change in reading is first observed; this ñrst show of
change will be at the moment tension iirst arrived at the
location of the instrument and will be a neutral point and
will give an operator sui’rìcient and accurate information
for “backing oíî” the pipe at this point.
It will, of course, be apparent that any suitable device,
such as a direct current meter may be substituted for the
understood that these are intended by way of illustration
only and that various changes may be made in the con
struction and arrangement of the parts of the apparatus
as well as in the particular steps of the method, within
the spirit of the invention and the scope off the appended
claims.
Having thus clearly shown and described the invention,
what is claimed as new and desired to secure by Letters
Patent is:
l. The method of locating the stuck portion of a well
pipe Strick in a well bore in which the free portion of the
pipe above the stuck portion is in a condition of stress
causing inclination of said free portion of the pipe above
the stuck portion comprising, measuring variations in the
inclination of the pipe along the pipe, and concurrently
measuring the depth at which said measurements are made
whereby the stuck point can be located as lbeing that por
tion of the pipe below which no variations in the inclina
tion of the pipe are noted.
2. The method of locating the stuck portion of a well
pipe stuck in a well bore comprising, placing the pipe
" above the stuck portion in a stress causing inclination of
the free portion of the pipe above the stuck portion, meas
uring variations inthe inclination of the pipe along the
pipe, and concurrently measuring the depth at which
recorder mechanism 42 when it is desired merely to indi 40 said measurements are made whereby the stuck portion
can be located as Ibeing that portion of the pipe below
cate to the operator when the stuck point is reached with
which substantially no variations are measured.
out making a record of the variations in inclination of the
3. The method of locating the stuck portion of a well
pipe.
pipe stuck in a well bore comprising, measuring the varia
In carrying out the method of the invention, the in
tions in the inclination of the pipe along the pipe while the
clinometer is lowered inside of the string of pipe whose
pipe is one condition of stress, concurrently recording the
variation in inclination it is desired to determine and
depth at Iwhich the inclination measurements are taken,
current is supplied to the inclinometer in the manner
applying a force to the pipe suf'ricient to cause the free
previously described, and the changes in inclination of the
portion of the pipe above the stuck portion to assume in
inclinometer are recorded as we show above, with the pipe
clinations different from those existing when the first
in a relaxed condition in the bore. As the inclinometer is
measurements are made, again measuring the variations
lowered in the bore, the deviation of the instrument from
in the inclination along the pipe while concurrently record
the vertical will be continuously recorded on the chart 44.
ing the depth at which the secc-nd inclination measure
When the inclinometer reaches the bottom, an upward pull
`ments are taken, and comparing the first and second
may be exerted on the string of pipe, which will tend to
measurements whereby the stuck portion is located as be
reduce the variations in inclination throughout the free
ing the portion below which no change of inclination
portion of the string above the stuck portion, and the
occurred in either measurement.
inclinometer may be moved upwardly through the pipe
4. The method of claim 3 wherein the step of applying
while the pipe is maintained in this condition to make a
a force to the pipe includes the steps of applying a lon
second recording of the variations in inclination. By com
gitudinal 'force to the pipe.
paring the two recordings thus produced, it will then be
possible to accurately locate the portion of the pipe which 60 5. The method `of claim 3 wherein the step of applying
is stuck in the bore and the portion which is free above
a force to the pipe includes the step of applying a torque
to the pipe.
6. The method of locating the upper stuck point of the
disconnected or cut olf to permit the removal of the free
stuck portion of a Well pipe stuck in a well bore compris
portion. During the carrying out of the method in this
manner, it will be apparent that the stuck portion of the 65 ing, measuring variations in the inclinationy of the pipe
along the pipe While the pipe is in one condition of stress,
pipe will be held against being affected by the upward pull
concurrently recording the depth at which the inclination
exerted on the string, so that the variations in inclination
measurements are taken, applying at the surface a force
of the stuck portion will remain substantially the same
to the pipe sufficient to cause the free portion of the pipe
While the variations in the inclination of the free portion of
the pipe will be changed, so that the location where the 70 above the stuck point to assume inclinations different from
those existing when the lirst measurements are taken, again
free portion of the pipe joins the stuck portion may be
the stuck portion, to determine where the pipe shall be
accurately located.
It will be apparent that under some conditions, the
location of the stuck portion of the pipe may be deter
measuring the variations in inclination along the pipe
while concurrently recording the depth at which the sec
ond inclination measurements are taken, and comparing
the first and second measurements whereby the upper stuck
3,039,544
poin-t is located las being the point below which no change
in inclination of the pipe occurred between the ñrst and
second measurements.
7. The method of substantially neutralizing the stress
in a tool joint of known position above the stuck portion
of a well pipe stuck in a well bore preliminary to discon
necting the tool joint comprising, placing an inclinorneter
in the pipe adjacent said tool joint, and applying =a force
to the pipe to remove the stress from the pipe at the tool
10
ing the variations of »the inclination of the inclinorneter
with reference to the variations of the inclination of the
pipe thereby locating the positions of the variations in the
internal diameter of the pipe.
10. The method of locating the positions of variations
in the internal diameter of a pipe in a well bore comprising,
moving an inclinometer through an in contact with the
pipe, concurrently measuring variations in the inclination
of the pipe, concurrently measuring the position of the
inclinometer in the pipe, and noting the variations of the
joint until the inclination of the pipe changes thereby in 10 inclination of the inclinometer with reference to the varia
dicating that the stress in the tool joint is substantially
tions `of the inclination of the pipe thereby locating the
removed.
positions of variations in the internal dameter of the pipe.
8. The method of substantially neutralizing the longi
tudinal stress in a tool joint of known position above the
stuck point in a well pipe stuck in a well bore preliminary 15
to disconnecting the tool joint comprising, placing an in-
clinometer in the pipe adjacent said tool joint, applying a
llongitudinal `force to the pipe in a direction to remove the
References Cited in the file of this patent
UNITED STATES PATENTS
2,078,426
2,190,901
2,686,039
2,746,550
2,761,218
`longitudinal stress `from the pipe at the tool joint until the
inclination of the pipe changes thereby indicating the lon 20
gitudinal stress in `a tool joint is substantially removed.
2,814,019
9. The method of locating the position of variations in
2,847,808
the internal diameter or" a pipe comprising, moving an in
2,851,784
clinometer through and in contact with the pipe thereby
measuring the inclination of the pipe, concurrently meas 25 2,905,437
2,936,411
uring the position of the inclinometer in the pipe, and not~
Sweet _______________ __ Apr. 2,7, 1937
Wilcox et `al ___________ __ Feb. 20, 1940
Bender ______________ __ Aug. 10, 1954
Mitchell _____________ __ May 22, 1956
Bielstein ______________ __ Sept. 4, 1956
Bender ______________ __ Nov. ‘19, 1957
Gieske _______________ __ Dec. 24, 1957
»Flatow ______________ __ Sept. 16, 1958
Bell et al _____________ __ Sept. 22, 1959
Doty ________________ __ May 10, 1960
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