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Publication numberUS3307642 A
Publication typeGrant
Publication dateMar 7, 1967
Filing dateJun 1, 1965
Priority dateJun 1, 1965
Publication numberUS 3307642 A, US 3307642A, US-A-3307642, US3307642 A, US3307642A
InventorsSmith William D
Original AssigneeGo Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Bore hole tool orienting apparatus and systems
US 3307642 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

March 7, 1967 w. D. SMITH 3,307,642

BORE HOLE TOOL ORIENTING APPARATUS AND SYSTEMS Original Filed March 15. 1963 2 Sheets-Sheet 1 ABOVE GROUND 2 7 EQUIPMENT ifm. T W M aflfamj March 7, 1967 w. D. SMITH 3,307,542

BORE HOLE TOOL ORIENTING APPARATUS AND SYSTEMS Original Filed March 15, 1963 2 Sheets-Sheet 2 REGULATED I03 DIRECT CURRENT 1 1 4 73 PowER SUPPLY T 6/ 63. 59 w PASS .75 I 77 I 1.0 65 -i6 FILTER AMPLIFIER I 67 RECORDER I PULSE RATE D R A 49 ISC lMlN ToR COUNTER z 37 5 9 9 4,5 A COLLAR VOLTAGE GUN GAMMA RAY LOCATOR REGULATOR L, 3 DETONATOR souRcE IO! L 1!.I

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Wfl/mmfi mzzh 6% rfifizzQ United States Patent 3,307,642 BORE HOLE TOOL ORIENTING APPARATUS AND SYSTEMS William D. Smith, Fort Worth, Tex., assignor to G0, Inc., Fort Worth, Tex. Continuation of application Ser. No. 265,469, Mar. 15, 1963. This application June 1, 1965, Ser. No. 466,493 3 Claims. (Cl. 175-451) This application is a continuation of my copending application, Serial No. 265,469 filed March 15, 1963, now abandoned.

The present invention relates to apparatus for orienting tools in bore holes, and more particularly to apparatus and systems wherein a tool is orientable relative to phenomena indicative of an azimuthal pattern.

The invention is especially applicable to apparatus and systems wherein a perforator device is orientable relative to plural tubing strings in certain types of so-called multiple completion wells. The term multiple completion well as used herein is specifically restricted to embrace only those types of multiple completion wells wherein a plurality of tubing strings are cemented in a bore hole at a perforating location. I

In earth formations traversed by a bore hole and wherein there are a plurality of petroleum bearing strata at different bore hole depths, it is now common practice to insert a plurality of tubing strings into the uncased bore hole and then, by cementing the bore hole, to isolate the strata outside the tubing strings from each other so that there may be provided a plurality of petroleum production zones. Multiple completion wells may in some cases involve many producing zones; with two to four producing zones being quite common. Tubing strings are usually run so that within a given production zone there may be a plurality of tubing strings. Now, after the tubing strings are installed and cemented, it is necessary to perforate the tubing string that is to carry the output of a particular production zone. This perforating is accomplished by lowering a perforating device (usually a shaped charge gun) within the tubing string to be perforated, then, orienting the device so that only the desired tubing string will be perforated, and then actuating the perforating device. It is essential in every case that the perforator device shall be fired so as to avoid perforation of any other tubing string. It is therefore quite apparent that apparatus and systems for accomplishing orientation of the perforator device should be dependably accurate and effective. Unfortunately, the apparatus and systems for accomplishing this orientation in the prior art of which I am aware, leave much to be desired.

It is accordingly a general object of this invention to provide improved perforator orienting apparatus and systems.

Another object of this invention is to provide perforator orienting apparatus and arrangements which shall be dependably and effectively accurate.

Another object of this invention is to provide perforator orienting apparatus and arrangements wherein the probability of producing and acting upon false orientation information is minimal.

Another object of this invention is to provide perforator orienting apparatus and arrangements wherein reliable orientation information is derived.

These and other objects are effected by this invention, as will be apparent from the following description taken in accordance with the accompanying drawings, forming a part of this application, in which:

FIG. 1 is a diagrammatic showing of the general layout of a perforating orienting apparatus and system utilizing the present invention, with the down-hole portion of the apparatus disposed inside a tubing string in a typical multiple completion well;

FIG. 2 is a schematic sectional view taken at line II-II of FIG. 1;

FIG. 3 is an enlarged fragmentary longitudinal section view showing in schematic form certain details of the drive section of the down-hole assembly of FIG. 1;

FIG. 4 is a schematic electric circuit diagram of the perforator orienting apparatus and system in accordance with a preferred embodiment of the present invention;

FIG. 5 is a graph showing in schematic form a typical strip chart produced by the apparatus of FIGS. 1 and 4; and,

FIG. 6 is a polar plot or orientation chart made up from information taken from the strip chart of FIG. 5.

Referring now to the drawings, in FIG. 1 there is shown a typical down-hole assembly 11 suspended within a tubing string 13 by means of a cable 15 which is reeled off a conventional cable drum 17 which is powered and controlled by conventional means (not shown). The cable 15, in addition to supporting the down-hole assembly 11, has an inner-conductor 19 which is insulated from the outer sheath 21 which acts as a common conductor. The cable drum shaft is provided with slip rings 23, with associated brushes 25, through which electrical signals are transmitted to and from the cable conductors to the downhole assembly 11 and to components of the above-ground equipment, indicated generally by the block 27. The first tubing string 13 is disposed together with second and third tubing strings 29, 31 within a typical uncased earth bore hole 33. The tubing strings are assumed to be cemented in the bore hole, but for clarity, the cement is not indicated in FIGS. 1 and 2 of the drawings.

The sections of the down-hole assembly 11 as shown by FIG. 1 may include, by way of illustration, reading from top to bottom, a cable head 35, a collar locator section 37, a motor drive section 39, a radioactivity detector section 41, a spacer section 43, a radioactivity source section 45, and a perforator device section 47. Secured on the down-hole assembly 11 in a conventional manner between the collar locator section 37 and the motor drive section 39 are a set of conventional drag springs 49. Also secured on the down-hole assembly 11 in a conventional manner immediately above the radioactivity detector section 41 and immediately above the perforator device 47 are respective sets of conventional centralizing springs 51, 53.

The various sections of the down-hole assembly 11 are coupled together and appropriately sealed against entry of well fluids, all in accordance with conventional down-hole tool practices. The upper sections of the down-hole assembly, namely the collar locator section 37 and the motor drive section 39 are of course movable up or down in the tubing string 13, but they are prevented by the drag springs 49 from having any rotational movement in the tubing 13. The lower sections of the downhole assembly 11, namely all sections below the motor drive section 39, are fixed to an output shaft 55 of the motor drive section 39. The cent-ralizer springs 51, 53 act to maintain the lower section centered within the tubing 13, but they do permit the lower sections 41, 43, 45, 47 to rotate within the tubing 13.

As shown in FIG. 4, the above-ground equipment (included within the block 27 of FIG. 1) includes a regulated direct current power supply 57, a first coupling capacitor 59, a low pass filter 61, an amplifier 63, a recorder 65, a second coupling capacitor 67, a discriminator 69, and a pulse rate counter 71. The regulated direct current power supply 57 may be of a conventional type capable of supplying about two hundred fifty volts at its output. The power supply output is connected via lead 73 to the center conductor 19 of the cable 15. The aboveground equipment provides a first channel, which may be termed the radioactivity signal channel, and a second channel, which may be termed the perforator position indicator channel. The recorder is of the two pen strip chart type, and also has two channels, one for each pen. In the perforator position indicator channel, the first coupling capacitor 59 is connected to the cable center conductor 19, and in series with the input of the low pass filter 61, the output of which is connected via lead to the input of the amplifier 63, the output of which is connected via lead 77 to the input of one channel of the recorder 65. In the radioactivity signal channel, the second coupling capacitor 67 is connected to the cable center conductor 19 and in series with the input of the discriminator 69, the output of which is connected via lead 79 to the input of the pulse rate counter 71, the output of which is connected via lead 81 to the input of the other channel of the recorder 65. I

As shown in FIG. 4, the down-hole assembly 11 includes the collar locator 37, a voltage regulator 83, a choke 85, a drive motor 87, a by-pass capacitor 89, a first diode 91, a second diode 93, a current limiting resistor 95, a perforator position signal generator 97, a gun detonator 99, gamma ray detector 41, and gamma ray source 45. The collar locator 37 is connected via lead 101 to the cable center conductor 19, and to common or ground at 103. A series circuit may be traced from the cable center conductor 19 via lead 105 through the choke 85 and via lead 107 through the motor 87 and via lead 109 through the gamma ray detector 41 and to common or ground at 103. The voltage regulator 83 is connected via leads 111, 113 in parallel with the drive motor 87. The by-pass capacitor 89 and the first diode 91 are connected in parallel and via lead 115 to lead 105, and via lead 117 to lead 109. The second diode 93 is connected to lead 109 and in series with the gun detonator 99 to ground at 103. The first and second diodes 91, 93 are poled to conduct in the direction away from common or ground 103. The perforator position signal generator 97 includes a ring 119 which is fixed to the motor drive output shaft 55 and rotates therewith. A first contact 121 rides on a portion of the ring 119 which is continuously conductive around the ring peripheral surface. The first contact 121 is connected to ground or common at 103. A second contact 123 rides on a portion of the ring 119 wherein the conductive portion is interrupted by a plurality of insulating segments 125 for a purpose to be hereinafter explained. The second contact 123 is connected in series with the current limiting resistor 95 to the lead 109. The gamma ray source 45 has no electrical connection, but is shown as a block in FIG. 4 for the sake of completeness.

Referring now to FIG. 3, the motor drive section 39 may include a first inner housing 127 containing the drive motor 87 and suitably supporting same within the drive section outer housing, and a second inner housing 129. Suitably mounted within the second inner housing are the choke 85, the voltage regulator 83, the bypass capacitor 89, and the first diode 91. The motor drives a gear reduction 131 which in turn drives the motor section output shaft 55. Also, the perforator position signal generator 97 is disposed on the output shaft 55 and within the motor drive section 39.

The operation of the perforator orienting apparatus and system of the invention may now be considered. The regulated direct current power supply 57 supplies about 250 volts at its output terminals. Of this voltage, some is dropped in the power cable 15, and some across the choke 85, leaving about 107 volts for the motor 87 and about 120 volts for the gamma ray detector 41. The motor 87 is of permanent magnet direct current type arranged to operate at a speed that will cause the output shaft 55 to rotate at an appropriate speed, for example, about 1 per second. The choke 85 may have a value of about 2 henries, and serves to filter out motor brush noise and thus prevents its transmission up-hole. The voltage regulator 83 may be a type 0B2 gas regulator tube, which serves not only to maintain a constant voltage across the motor 87 and thus keep the motor speed constant, but also to conveniently by-pass direct current power to the gamma ray detector section. The collar locator 37 may be a conventional magnetic type the output signals of which are indicated by above-ground equipment not shown. The radioactive source may be of any suitable conventional type, with a corresponding conventional detector section, In the embodiment shown, the radiation source is simply apellet of radioactive material which produces gamma radiation, and the detector is of a conventional type which produces output pulse signals at a rate which is proportional to the quantity of gamma radiation present at the detector input. It will of course be recognized that the gamma ray source 45 as well as the detector 41 must have azimuthal directional properties. This is conventionally and conveniently accomplished by shielding both the source and the detector with suitable high density materials, so that each has only a window or unshielded portion located in the same vertical plane. One satisfactory arrangement for this purpose is shown and described by M. P. Lebourg and W. T. Bell: Perforating of Multiple Tubingless Completions, in Journal of Petroleum Technology, May 1960, vol. 219, pp. 88-93. The perforator device 47 may be of any appropriate conventional type, but in the embodiment shown is a shaped charge g'un of the non-expendable type wherein a plurality of shaped charges 133 are mounted in a carrier and are all oriented to fire in the same direction. Included within the gun carrier is the conventional gun detonator device and arrangement 99, including the second diode 93.

To perform a perforating operation, the down-hole assembly 11 is lowered inside the tubing string 13 to be perforated and into the bore hole 33 to the desired depth within the chosen production zone. The depth positioning is done in a conventional manner utilizing the collar locator 37 along with bore hole log information that was previously obtained. After the down-hole assembly 11 has been positioned at the desired depth the orienting apparatus is energized so that orientation recording operations may begin. The motor 87 then starts running, so that the gamma ray detector 41 rotates, with the window (not shown) at its output scanning the bore hole 33 in the radial directions from the detector rotational axis. In about six minutes, the detector will scan one full revolution, or 360 (assuming that the output shaft 55 is driven at about 1 per second).

The recording operation is arbitrarily started from whatever azimuthal position the detector 41 happens to be in when the apparatus is energized. As hereinbefore mentioned, the recorder has two pens, the first of which makes a first trace on the strip chart in accordance with the output of the radioactivity signal channel and the second of which makes a second trace in accordance with the output of the perfora-tor position indicator channel. A typical strip chart that has been produced in accordance with the present invention is shown schematically in FIG. 5, wherein the right hand or first trace 135 was produced by the first recorder pen and the left hand or second trace 137 was produced by the second recorder pen. The numbers at 'the left of the chart correspond to 24 equal intervals in a single scanning revolution, and are thus each 15 scanning degrees apart.

The radiation which the detector 41 sees as it scans is converted to pulses by the detector section, which pulses are transmitted via lead 109, by-pass capacitor 89, leads 105, to cable 15 and thence up-hole and via coupling capacitor 67 to the discriminator 69. The discriminator 69 acts to separate the radioactivity signal pulses from the other signals present on the cable 15, and then passes the separated pulses to the pulse rate counter 71. The pulse rate counter integrates the pulses and delivers to the recorder 65 a signal which varies in magnitude proportional to the pulse rate, which in turn is a function of the radiation present at the input of the detector 41. The recorder 65 then produces the chart first trace 135 as the scanning operation proceeds.

As the detector 41 performs its scanning operation the ring 119 of the perforator position signal generator is also rotating at the same rate of about 1 per second, or about one revolution per six minutes. The ring 119 is continuously connected to common or ground 163 by means of the first contact 121 which continuously rides on the conductive portion of the ring. The second contact 123 rides the conductive portion of the ring 119 during spaced intervals within each scanning revolution, and during these conductive intervals the current limiting resistor is connected via the contacts 123, 121 to common or ground. These conductive intervals are however interrupted by the presence of the insulating segments 125. There are 23 insulating segments 125 disposed with their outer surfaces on the cylindrical peripheral surface of the ring 119 such that there is a junction between a trailing edge of an insulating segment and the leading edge of a ring conductive portion at each 15 interval of the ring surface except at one place, where the interval is 30 for a purpose to be hereinafter explained. These junctions are represented on the chart of FIG. 5 by the numbers 1 through 24 (with only odd numbers being shown and with a gap indicating no junction at position 3).

Each time the second contact 123 arrives at a junction, the regulated direct current power supply 57 is shunted via current limiting resistor 95 to ground 193. This shunting action produces a slight but abrupt change in direct current load current resulting in the production of a transient signal which is immediately sensed aboveground by the perforator position indicator channel. The transient signal is transmitted from the cable 15 via coupling capacitor 59 and low pass filter 61 to the input of the amplifier 63. The low pass filter 61 acts of course to exclude signals other than the desired transient. The amplifier 63 is assumed to include suit-able conventional means for shaping the transient signals to the sharp marker or position indicator pulses 1355 that appear on the recorder second trace 137. The amplifier 63 is also assumed to include suitable conventional means to exclude the unwanted or extraneous transient signal that is produced when the second contact 123 arrives at junction at the conductive portion trailing edges and the insulating segment leading edges.

When the recordng operation has proceeded for a sufficient time to produce postion marker pulses 139 for at least one complete revolution of the detector 41 and including at least two gaps in the position marker pulse train, the apparatus may be de-energized. It being known that the position marker gaps always occur at position 3, these gap positions may be numbered 3 on the chart and then the rest of the position numbers may be properly applied to the chart. The chart positions are now definitely correlated with the aforementioned junction positions on the ring 119, and therefore also with the corresponding detector positions. Thus, at the instant the contact 123 arrived at a given junction, as represented by a position marker pulse on the chart, the first trace recorder pen was indicating at the same chart position the radiation magnitude seen by the detector at the same instant. It is thus apparent that the recorder second trace 137 provides position indicator markers 139 which positively correspond to the orientation of the detector 41 and are positively correlatve with the recorder first trace 135.

It is known that when the radioactivity source is incorporated in the down-hole assembly within the tubing to be perforated, which is the case thus far herein descrbed, the radiation at the detector input is minimum when the detector is seeing an obstruction. Thus it may be observed in FIG. 5 that the first recorder trace 135 is at a minimum in the region where it most nearly approaches the second trace 137, or roughly between positions 6 and 12. It can be seen from FIG. 2, wherein markers are numbered 1 through 24 and and are oriented correlative to those bearing like numbers in FIG. 5, that the obstruction in the form of the second and third tithing strings 29, 31 do in fact occur in the region between numbers 6 and 12. It is also apparent that a safe direction to fire the perforator gun 47 would, be in the direction opposite or away from the central portion of the obstruction region. This desired firing direction is then clearly at about position 21. It is noted that the gun 47 in FIGS. 1 and 5 has been oriented so as to fire at position 21, as is evidenced by the orientation of the shaped charges 133. It will be obvious to those skilled in the art that the perforator gun 47 has been initially oriented in a known manner relative to the detector 41. While no particular specific orientation relation is essential, the most convenient is to have the gun pointed 180 away from the detector.

In order to actually fire the gun it is only necessary to momentarily reverse the polarity of the direct current power supply (by conventional means not shown) so that current may pass from ground 103 through the gun detonator 99, diodes 93, 91 and lead to the cable center conductor 19 and thence up-hole to the power supply 57 and again to ground 103.

In practice it is convenient and helpful to translate the information produced on the recorder .strip chart (FIG. 5) to a polar plot or chart as shown in FIG. 6. To accomplish this, the radial lines of the polar chart paper are marked with position numbers 1 through 24 correlative to the same numbers on the strip chart. In addition, an arbitrary zero line 141 disposed parallel to the direction of strip chart movement is established on the strip chart as indicated in FIG. 5. The zero line 141 is not to be confused with the recorder zero output signal trace, which would be to the left of trace 137 in FIG. 5. Then the points on the recorder first trace 135 corresponding to each position marker (for example, points A and B corresponding respectively to position markers 5 and 7) are determined. Then the corresponding points are determined on the polar chart (FIG. 6) by measuring the distance between the zero line 141 and the determined point on the recorder first trace 135 and then laying off such distance (or a proportional distance) on the proper radial of the polar chart. In this manner, the curve or trace 143 of the polar chart is plotted. It is noted that the solid line portion of the trace 143 may be considered to begin at position 5 (point A) and proceed counterclockwise around the plot to close at position 5. However, there is a dotted line porton of trace 143 that extends between position 5 and position 24. This dotted line merely indicates that the first recorder trace 135 covers a complete revolution of the detector 41 plus a portion of a second revolution.

It is easy to see from the trace 143 of the polar plot that the obstructions (tubing strings 29, 31) are in the region between radials or positions 6 and 12, and that the gun 47 can be safely fired toward position 21 as indicated by the arrow.

From the foregoing it will be apparent that a first important concept of the present invention is to generate at the down-hole assembly orienation signals which are positively related to discrete azimuthal positions of the detector and the perforator device, and to present and record such orientation signals at the above-ground equipment in positive time correlation with the presentation and recording of corresponding detector output signals. A second important concept of the present invention is to interpose in a sequential train of the orientation signals above-mentioned a periodically recurring identifiable anomaly.

Application of the first concept above-mentioned provides the equipment operator with positive indicatons of the azimuthal movement of the detector, such indications being positively correlated with the detector output signals. Thus, the likelihood of acting upon false orientation information is substantially reduced. Application of the second concept above-mentioned together with the first, provides the equipment operator a Way to check the veracity of the orientation signals and thus ensures that the orientation information acted upon isunmistakably accurate and dependable. Also, application of said second concept obviates the necessity of establishing a predetermined initial orientation of the tool.

The preferred embodiment of the present invention as shown and described herein demonstrates one way which the important concepts above-mentioned may be applied in practice to achieve the desired results. It is realized, of course, that the actual physical configuration of the apparatus used to apply said concepts may certainly be varied in a number of ways that will be apparent to those skilled in the art. For example, there are certainly various ways in which the orienting signals could be initiated in the down-hole assembly, and there are various ways in which they could be presented to the above-ground equipment. Also, the anomaly above-mentioned could take various forms and could be produced by various means. Further, the radiationsource (in cases where radioactivity signals are employed) need not necessarily be carried by the down-hole assembly); it may, if desired, be suspended in another tubing string.

The foregoing disclosure and the showings made in the drawings are merely illustrative of the principles ofthis invention and are not to be interpreted in a limiting sense.

I claim:

1. Apparatus for perforating in a bore hole having a plurality of tubing strings disposed therein in side by side relation comprising:

(a) a down-hole assembly including a first section and second section;

(b) above-ground equipment;

(c) means for disposing said down-hole assembly within a first one of said tubing strings which is to be perforated at the desired perforation depth;

(d) means included in said first section of said downhole assembly for preventing rotation of said first section relative to said first tubing string;

(e) means included in said first section of said downhole assembly for rotating said second section relative ot said first section;

(f) a perforating tool, a radioactive source, and a radioactivity detector included in said second section;

(g) means included in said down-hole assembly for generating orientation signals which are positively related to azimuthal positions of said detector;

(h) said orientation signal generating means including means to interpose in a sequential train of said orientation signals a periodically recurring identifiable anomaly;

(i) means for transmitting signals derived from said detector, and said orientation signals to said aboveground equipment;

(j) and means included in said above-ground equipment for recording said signals.

2. Apparatus for perforating in a bore hole having a plurality of tubing strings disposed therein in side by side relation comprising:

(a) a down-hole assembly including a first section and a second section;

(b) above-ground equipment, and a down-hole signal source;

(c) means for disposing said down-hole assembly within a first of said tubing strings which is to be perforated at the desired perforation depth;

(d) means included in said down-hole assembly for preventing rotation of said first section relative to said first tubing string and for rotating said second section relative to said first section;

(e) detector means included in said second section and responsive to said down-hole signal source, for generating signals indicative of the azimuthal locationv of other said tithing strings relative to said first tub-- ing string;

f) a perforating tool included in said second section;

(g) means included in said down-hole assembly for generating orientation signals which are positively related to azimuthal positions of said detector;

(h) said orientation signal generating means including: means to interpose in a sequential train of said orientation signals a periodically recurring identifiable anomaly;

(i) means for transmitting signals derived from said detcctor, and said orientation signals to said aboveground equipment;

(j) and means included in said above-ground equipment for recording said signals.

3. Apparatus for orienting a tool in a bore hole comprising:

(a) a down-hole assembly including a first section and a second section;

(b) above-ground equipment, and a down-hole signal source;

(0) means for disposing said down-hole assembly with in the bore hole at a desired depth;

(d) means included in said down-hole assembly for preventing rotation of said first section relative to the bore hole and for rotating said second section relative to said first section;

(e) detector means included in said second section and responsive to said down-hole signal source, for generating signals indicative of an azimuthal pattern;

(1) a tool to be oriented included in said second section;

(g) means included in said downhole assembly for generating orientation signals which are positively related to azimuthal positions of said detector;

(h) said orientation signal generating means including means to interpose in a sequential train of said orientation signals a periodically recurring identifiable anomaly;

(i) means for transmitting signals derived from said detector, and said orientation signals to said aboveground equipment;

(j) and means included in said above-ground equipment for recording said signals.

References Cited by the Examiner UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner.

D. H. BROWN, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3097693 *Jul 21, 1960Jul 16, 1963Jersey Prod Res CoMethod of perforation of well pipe
US3143170 *Jan 23, 1959Aug 4, 1964Jersey Prod Res CoMethod and apparatus for borehole operations
US3175608 *Oct 21, 1960Mar 30, 1965Dresser IndMethod and apparatus for directional tubing perforation
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3704749 *May 6, 1971Dec 5, 1972Nl Industries IncMethod and apparatus for tool orientation in a bore hole
US3964553 *Sep 4, 1975Jun 22, 1976Go International, Inc.Borehole tool orienting apparatus and systems
US5259466 *Jun 11, 1992Nov 9, 1993Halliburton CompanyMethod and apparatus for orienting a perforating string
US5351755 *Aug 2, 1993Oct 4, 1994Texaco Inc.Method and apparatus for establish the orientation of tools in a cased borehole
US6173773Apr 15, 1999Jan 16, 2001Schlumberger Technology CorporationOrienting downhole tools
Classifications
U.S. Classification175/4.51, 166/66, 73/152.54, 166/55.1
International ClassificationE21B43/119, E21B43/11
Cooperative ClassificationE21B43/119
European ClassificationE21B43/119