US3106960A

US3106960A - Method of and means for positioning apparatus in well casings

Info

Publication number: US3106960A
Application number: US1219A
Authority: US
Inventors: Howard J Doak
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-01-08
Filing date: 1960-01-08
Publication date: 1963-10-15
Anticipated expiration: 1980-10-15

Description

l b b U SLAHCHROOM Oct. 15, 1963 H J, DOAK 3,106,960

METHOD OF AND MEANS FOR POSITIONING APPARATUS IN WELL CASINGS Filed Jan. 8*, 1960 5 Sheets-Sheet l FVG. 2

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3,106,960 METHOD OF' AND MEANS FOR POSITIONING APPARATUS IN WELL CASINGS Filed Jan. 8, 1960 H. J. DOAK Oct. 15, 1963 5 Sheets-Sheet .I5

United States Patent O 3 106,960 METHOD OF AND IEANS FOR POSITIONING APPARATUS IN WELL CASINGS Howard J. Doak, 3311 E. 45th St., Tulsa, Okla. Filed Jan. 8, 1960, Ser. No. 1,219 6 Claims. (Cl. 166-66) This invention has general reference to the location of apparatus and equipment of various kinds, in cased bore holes. More specifically, the invention has reference to a method of `and means for positioning said apparatus in oil well casings, during wire line operations wherein it is necessary to lower a particular piece of equipment, on a wire line, to a predetermined depth with a minimal loss of accuracy in the determination of the exact position at which the apparatus is to be placed in use.

In wire line operations, such as perforating the well casing, setting cement retainers, bridge plugs, and permanent packers, the normal procedure is to lower the perforating gun or other tool into the hole, with a collar locator attached. The collar locator is used to identify collars which have previously been logged on a correlation-collar 10g.

Presumably, one might expect to be able to lower the tool to the exact depth desired, merely by noting the response on the conventional collar log, during the descent of the tool with its attached collar locator. However, difculties are encountered, owing to the fact that deviations occur in the wire line, ias the operation progresses, due to changes in tension, weight, temperature, etc. These deviations can have great significance, and if not properly calculated and compensated for, can easily result in animproper positioning of the apparatus. In wells of great depth, an oil-producing stratum may be no more than a few feet in thickness, and thus it will be seen that it is exceedingly important to locate a perforating tool with complete accuracy, so that perforation of the casing will occur at the exact location of the producing stratum. The same requirement for complete accuracy exists, as will be readily appreciated, in connection with various other types of wire line operations.

It is often difficult, in this regard, to identify a particular collar, without lowering the perforating gun or other tool fully to the bottom of the casing for the purpose of checking or calculating accuracy of the wire line. This, of course, is a time-consuming operation, and even so, is not fully productive of complete accuracy. The use of casing collars as markers, that is, as datum points, is obviously a secondary function of the casing collars, since their primary function is to join together adjacent, abutting lengths of the pipe of which the casing is formed. Thus, the spacing of the markers constituted by the casing collars is determined by the lengths of the pipe sections, and is not necessarily an optimum spacing of casing markers employed during the positioning of apparatus in wire line operations. In other words, one is required to use as a marking means or datum, a piece of equipment, the primary function of which is something other than the provision of a reference point.

Normal procedure, during oil well completion operations, is to prepare a correlation log. Graphically depicted upon a log of this type is at least one correlation curve, showing the various formations or strata through the use of an undulant line, the deviations of which indicate the different formations. The correlation log, further, includes a collar log, immediately adjacent :the correlation curve, the collar log constituting a diagrammatic representation of the oil well, showing the position of the casing collars or couplings, and quite possibly other components of the casing, including float collars, guide shoes, stage cementing collars, etc. i

3,106,960 Patented Oct. 15, 1963 ICC The correlation log is prepared through the use of existing equipment, and thus, conventional logging tools, available to the oil industry, are regularly used to identify depth relationships with adjacent formations in wells. Said logging equipment, as already known to the industry, further includes collar locators, which are adapted to transmit signals to the surface, as they move past casing collars or couplings.

Thus, after a well casing has been installed, a correlation log of the type 'described above is prepared, and is thereafter used for positioning apparatus during wire line operations, such as perforating the casing, setting cement retainers, etc. In the perforation of the casing, for example, a perforating gun must be lowered by means of a wire line to the producing formation, which might be only a few feet thick and which will likely be at a great depth. On proper positioning of the perforating gun, said gun is triggered from the ground level. The gun thus lires projectiles or jets through the casing, into the producing formation, to complete the operation of perforating the well casing. j i

The general practice, during an operation of this type, is to lower the perforating gun or other tool into the hole with a collar locator attached. As the tool moves downwardly, the collar locator is used to identify collars which have previously been logged on the above-mentioned collar log. Ultimately, one of the collars becomes a reference point, with respect to the producing formation or other level of the well at which the tool is to be positioned.

It is often difficult, however, to identify a particular collar without lowering the gun or other tool fully to the bottom of the well -to check the accuracy of the wire line. This, as will be readily understood, is a time-consuming process, and even so, is productive of inaccuracies.

The locating of the gun or other apparatus, as noted previously, must be accomplished with exceedingly high accuracy, since the thickness of the oil-bearing sands may sometimes be no greater than a few feet. Not infrequently, the tolerance for work of this type cannot be permitted to exceed one or two feet in a total depth of perhaps 10,000 to 12,000 feet. Precision positioning of the apparatus, as will be appreciated, thus becomes a task of great dilliculty.

Complications and uncertainties arise in the positioning process, since the common practice is to determine depths in the bore hole from drill pipe measurements, as distinguished from depth measurements made in wireline operations, wherein the measurements are made by calculating displacements of the elastic suspension cable supporting the apparatus.

The factor of making corrections on account of the elasticity of the suspension cable produces the complications and uncertainties hereinbefore referred to. The extent to which the suspension cable stretches bears a relationship to the load -applied thereto, and is related, further, to the amount of cable payed out. Accordingly, when any device, such as a perforating tool, is lowered into a Well in wire line operations, corrections must be made in footage tabulations, in accordance with comparatively complicated, theoretical factors of deviation.

To overcome the difficulties discussed above, it has been heretofore proposed to provide marking means, other than the conventional casing components. For example, it has been proposed to fire a projectile of radioactive or magnetic material,` directly into a formation at a predetermined depth, whereby to establish a reference point on which all subsequent measurements may be based. It has also been proposed to form openings directly in the well casing, which openings are then plugged with magnetic material. Still further, it has been proposed to attach an iron shoe or the like to a casing, at a particular point along the length thereof, which shoe will provide a reaction at the ground surface when a suitable sensing instrument or detecting tool moves to a positlon abreast of the same.

The -arrangements heretofore devised have not gained widespread success, and this may be due to the fact that they have had on-ly single-purpose or at least highly limited use, in respect to positioning apparatus of various types. For instance, the special marking means lheretofore device have been utilized for the purpose olf aiding in the positioning of perforating guns, but are not usable, lany more than the casing collars themselves, in the eilicient, accurate positioning of other types of apparatus that might have to be located at a substantial distance from the producing formation. Further, in an instance in which the marker is applied by means of a piece of equipment lowered into .the well casing, it may readily happen that the marker itself will be inaccurately positioned, since its accurate llocation depends upon the correspondingly exact positioning of the equipment which is lowered into the casing for the purpose of firing or otherwise applying the marker.

Alternatively, when the marker is applied to the casing, it is undesirable to require re-design of the casing itself for the purpose of receiving a marking insert, in a recess or opening specially formed in the wall of the casing.

To overcome these disadvantages, it is an important object of the present invention to provide casing markers that can be produced in quantity, at relatively low cost, and applied 4to a well casing at any selected locations along t'he length of a casing section, including locations between the casing collars or couplings, all without any re-designing, drilling, or other modification of the conventional casing construction. Another object of importance is to provide a casing marker which will be characterized by the swittness and ease with which it can be slipped onto a casing, secured thereto at a selected point, :and thereafter permanently retained in posi-tion, dur'ing the conventional procedure of running a pipe string into the bore hole.

A further object is to provide a casing marker which will be be so designed as to insure to the maximum extent against any interference with normal casing installation, well completion, or pumping operations following perforation of the casing.

Another object is to speed up, to a marked degree, any wire line operations, including not only perforating, but also other operations such yas the setting of bridge plugs, through the provision of a plurality of the casing markers, regularly spaced along the entire length of the casing and logged at ground level in vthe same manner as the conventional casing collars are logged. Itis proposed, in this regard, to accomplish the speeding up of the wire line operations through the provision of the series of spaced markers, any one of which can be swiftly located in relation to an adjacent formation, to provide a datum point, without the necessity of lowering the apparatus fully to the bottom of the well for the purpose of checking the wire line accuracy.

A further object is 'to increase accuracy of positioning of apparatus while, at the same time, speeding up said positioning in the manner described above. In this regard, it is proposed to increase the accuracy by eliminatting the necessity of calculating deviations in wire line elasticity, to a maximum extent. In this way, the possibili'ty of human error is measurably reduced.

A further object is to promote speed and accuracy in positioning a tool at a predetermined depth, through the provision of a regular spacing of the markers in an arrangement that includes main markers that are uniformly spaced along the length of the well, in association with auxiliary markers, regularly spaced apart in the intervals occurring between adjacent main markers. In this way, it is proposed, in effect, to calibrate, so to speak, an oil well over its entire depth, in much the same way as one would calibrate a. rule with main indicia and with subindicia that represent fractional distances between adjacent main markings or gradations.

Another object is to so design the marker as to permit interchangeab-ility of component parts thereof, as between the main and auxiliary marking devices. rIlhus, a retaining sleeve and `a pair of locking rings embodied in the invention may be common to both the main and auxiliary marking devices, in `accordance with the invention, thus to lower the over-all cost of manufacture while, at the same time, simplifying assembly of the marking devices.

A further object is to permit incorporation of the invention in a conventional casing coupling, if desired.

Other objects will appear from the following description, the claims appended thereto, and from the annexed drawing, in which like reference characters designate like parts through the several views, and wherein:

FIGURE l is a side elevational view of one of the auxiliary marking devices formed according to the present invention, a casing section to which the same is applied being shown fr-agmentarily, in dotted lines;

FIGURE 2 is an end view of the retaining sleeve embodied in the marking device, as seen from the line 2-2 of FIGURE l;

FIGURE 3 is an end view of the marking device shown in FIGURE l;

FIGURE 4 is a transverse sectional view substantially on line `4-4 of FIGURE l;

FIGURE 5 is a longitudinal sectional view substantially on line 5 5 of FIGURE 2;

FIGURE 5a is a view like FIGURE 5, showing a main marker;

FIGURE 6 is a diagrammatic representation of an oil well, illustrating the various formations or strata penetrated thereby, in relation to` conventional well casing components;

FIGURE 7 is a diagrammatic representation, illustrating a through casing correlation -log including correlation curves and a conventional collar log, in connection with the well diagrammatically shown in FIGURE 6;

FIGURE 8 is a view like FIGURE 6, showing in a diagrammatic fashion auxiliary and main marking devices attached to the casing in accordance lwith the present invention;

FIGURE 9 is a correlation log according to the present invention, having the positions of the aux-iliary and main marking devices graphically delineated thereon;

FIGURE 10 is a diagrammatic showing of the well illustrtaed in FIGURE 6, showing a fragmentary portion of said well on a scale slightly enlarged above that of FIGURE 6, and illustrating a collar locator and associated perforating device, said locator and perforating device being shown in dilerent dotted line positions to which the same may be lowered; and

FIGURE 1l is a view like FIGURE 10, showing the lower portion of the well illustrated in FIGURE 6, and illustrating a conventional logging tool and collar-locator in use during the logging of a well, the casing of which is equipped with marking devices according to the present invention.

Referring to the drawing in detail, I have shown, in FIGURES 1-5, one form of marking device adapted for carrying out the invention. In this form of the invention, which constitutes a presently preferred embodiment, I provide an elongated casing marker applicable to a conventional oil well casing or pipe generally designated 10.

The marker shown in FIGURES 1-5 has been generally designated 12, and includes an elongated retaining sleeve 14 the outer diameter of which is slightly less than half the length thereof, the inner diameter lof the sleeve being slightly greater than the diameter of the well casing, so as to permit the sleeve to be slidable upon the well casing to a selected location.

As shown to particular advantage in FIGURES 4 and 5, I provide, midway between the opposite extremities of the retaining sleeve 14, a pair of diametrically opposed, transversely curved recesses 16, each of which is curved through approximately 90 degrees of the inner circumference of the retaining sleeve. The recesses 16 are comparatively shallow, so .that the retaining sleeve remains of appreciable thickness and strength at the location of the recesses. The recesses are concentric with one another and with the retaining sleeve, and each recess has straight side walls 18 intersecting perpendicularly with end walls 20, corresponding end walls of the recesses being aligned transversely of the retaining sleeve, on a line perpendicular to the axis of said sleeve.

In the illustrated, presently preferred embodiment, I form diam'etrically opposed radial openings 22 in the retaining sleeve, `communicating between the outer surface of the sleeve and the recesses. The openings communicate with the recesses at the center point of the recesses, whereby to be disposed in registration with threaded sockets 27 formed in the convex outer surfaces of transversely curved insert plates 24. Plates 24 are formed complementarily to the recesses, so as to ll the recesses in the manner shown in FIGURE 4. The plates, thus, have concave inner surfaces ilush with the wall 2S of the bore of the sleeve.

Designated at 26 are screws or equivalent threaded fastener members, extending through the openings 22 so as to be threadedly engaged in the sockets 27. In this way, the insert plates or elements 24 are xedly secured in position, within their associated recesses 16. The screws, at their outer ends, do not project beyond the outer circumference of the retaining sleeve, in the illustrated, preferred embodiment.

At 28 I provide a pair of identical, oppositely arranged locking or clamping collars, abutting against the opposite ends of the retaining or support sleeve 14, in the installed position of the marker 12.

The collars 28 are respectively `formed with arcuate collar members 29, the maximum diameters of which are no greater than the outer diameter of the sleeve 14, when the collar members 29 are secured 1in position about the casing. The collar mem-bers are adapted to be radially contracted into gripping engagement with the casing, thus to hold the sleeve 14 against endwise movement from its assigned position.

For the purpose of contracting the collar members, there are provided studs 30 each of which is formed, at its opposite ends, with threads of opposite hand. Wrenchreceiving enlargements or collars 32 are provided upon the studs, intermediate their ends, so as to facilita-te treading of the studs into or out of confronting, oppositelythreaded recesses 31 formed in the ends of the collar member.

Thu-s, it will be readily seen that in applying the device to the casing, one merely slips a collar 28 onto the casing section, before said casing section is run into the bore hole. Then, the sleeve 14 is similarly applied to the casing section, and is slidably adjusted to the selected point at which it is to be secured imm-ovably to the casing section. The other collar 28 is now applied, after which the collars, in abutting relation to the sleeve 14, are radially contracted, so as to permanently secure the sleeve to the casing, with the elements 24 in direct contact with the surface of the well casing.

A marking device such as shown in FIGURES 1 5 can appropriately ibe considered as an auxiliary marker, containing a single pair of diametrically opposed plates or elements 24. The plates or elements would be formed of a material that is designed to produce a reaction in a sensing or detecting instrument, such as a conventional collar loca-tor. The material used for the elements 24 would be selected according to `the type of collar locator or other logging tool that is to be employed.

Thus, it may be noted that many collar locators in use today work on the principle of a magnetic field. In this event, the elements 24 might -be permanent magnets. As

the collar locator moves to a position abreast of the elements 24 of a marker 12, a reaction would `be produced at the surface, translated into a deviation upon a correlation curve disposed adjacent a log on which the positions of the markers are charted.

In other instances, the elements 24 might be of a radioactive material, used with a logging tool that reacts by accentuating the characteristic curves on a gamma-ray neutron log. Then, too, the elements `could be of lead, s'o as to tend to reduce or shield completely the signal from a gamma-ray neutron logging tool. Other materials might be employed, as long as they will produce a reaction at ground level when a suitable sensing instrument or logging tool is lowered into the casing past the markers.

At periodic intervals along the length of the casing, there may belocated what might appropriately -be termed a main marker, such as one shown by way of example in FIGURE 5a. This marker would be one that would produce a different type of reaction at .the ground surface, from that produced `by the markers having only one type of element 24, such as shown in FIGURES 1-5. In FIGURE 5a, the marker has been generally designated 12a, and includes a support sleeve 14a, having diametrically opposed recesses 16a, exactly as in the iirst form of the invention. In this form of the invention, there could tbe mounted in each recess a plurality of elements 24a, 2411, 24C. Elements 24a might be of the same material as the elements 24. This would also be true of elements 24C. Elements 2411, however, might be of a different material, so as to produce a different reaction at the ground level. Assuming, for example, that

elements

24, 24a, and 24e are of permanent magnet material, the elements 24h might be `of a radio-active material, and the logging tool lowered into the bore hole could be prepared in such a way as to have a sub-assembly reacting to permanent magnets, and another sub-assembly reacting to radioactive material. In this way, at the -ground level there would lbe logged a plurality of regularly spaced auxiliary markers, after which there would appear on the log a main gradation, followed by a plurality of the subordinate or auxiliary gradations, etc.

Alternatively, a main marking means could comprise merely a plurality of the markers shown in FIGURE 1, disposed in end-to-end, abutting relation. One might employ, `for example, two sleeves 14 disposed in endabutting relation, with collars 28 lbeing disposed at opposite ends of the pair of sleeves. In this way, only one material need be used for the elements 24,` requiring in turn only one type of sensing instrument or logging tool.

In any event, itis mainly important to note at this time that the invention embraces the concept of main markers used to designate main reference or datum points, together with auxiliary markers used to designate subordinate datum points. One could lower a tool directly to a main marker, and using this as a datum point, could then raise or lower the tool to a selected auxiliary marker, using this as an auxiliary reference point, thereafter moving the apparatus to the selected position.

It may also be noted that by reason of the construction illustrated and described, main or auxiliary :markers could be assembled directly on the site, as necessary, during the lowering of the casing into the bore hole. A selected type of marker can be assembled, slid onto the next casing section that is to be coupled, secured in place at the prescribed location along the length of said section, and thereafter, the casing section may be coupled to the next ylower section, and lowered in-to the hole. Further, the arrangement permits interchangeability of components ofthe dev-ice, so that a sleeve such as shown Iat 14a can be used to receive either a plurality of elements in the manner shown in FIGURE 5a, `or alternatively, can be used to receive a single element such as shown in FIGURE 5 at 24.

In FIGURE 6, a typical well has been shown diagrammatically. In the illustrated example, the welll bore penetrates numerous formations, -designated A through K. By

way of example, two portions of the well are shown. The upper portion represents a section extending from formation A to lformation E, from approximately 7900 `feet to approximately 8200 feet. The lower section covers formations F through K, and extends from approximately 10,000 feet to approximately 10,400 feet. The Well casing 10 is illustrated diagram-matically, as being composed of a plurality of casing sections 34 each of which covers a distance of 331/3 feet. The sections are joined together by casing collars or couplings 36 of conventional construction. At approximately 10,290 feet, the casing is Iprovided with a tloat shoe 40. This is on the lower extremity of the casing, and disposed approximately l or l5 feet thereabove -is a oat collar 38. The well bore has been designated at 42, and the open space below 10,290 feet represents an open hole or uncased section 44.

In FIGURE 7, there is shown a conventional through casing correlation log, for the well shown in FIGURE 6. The correlation log includes first and second correlation curves 46, 48, derived from the use of conventional logging tools, Iwhich are lowered into the bore 42 fully to the bottom thereof to produce reactions as said tools pass the several formations A through K. The nature of the formations is such as to cause the logging tools to res-pond thereto, with the response being transmitted to the surface and being translated into a graphic representation on the log, as shown at 46, 48, respectively.

Between the correlation curves 46, 48, there is illustrated a collar log 50. This has the various well levels marked thereon, in gradati'ons of 100 `feet each. Through the use of collar locators, the log is provided with markings 52, at intervals of 331/3 feet, indicating the positions of the casing collars 36.

Heretofore, the general practice has been to use a correlation log `such as sho-wn in FIGURE 7. However, inaccuracies have been produced, as well as the loss of time due to the fact that in wire line operations, it has been necessary to lower the apparatus fully to the bottom, to check the wire line accuracy. Further, it is often difficult to identify a particular collar.

In FIGURE 8, there is diagrammatically shown a well, the casing lof which is provided not only with the conventional casing section-s 34 and casing collars 36, but also, with auxiliary and main markers 12, 12a, respectively, according to the present invention.

It will be seen that by way of example, I have attached an auxiliary marker 12, of the type shown in FIGURES 1-5, to the casing at a depth of 8,050 feet. Another one of the markers 12 is attached to the lower end of the casing, immediately below the float shoe 40, at approximately 10,29() rfeet. A main or composite marker 12a is attached at 10,150 feet. The middle element 24h of the marker 12a can be considered as a center marking element, said 4middle element bei-ng flanked by elements 24a, 24C.

In the illustrated arrangement, the marking elements are selected in such a way that the element of the marking device 12, shown abreast of formation B in FIGURE 8, would primarily aifect the collar log 50, at the mentioned depth of approximately 8,050 feet indicated on said log. Referring to FIGURE 9, a rst auxiliary marking S4 would thus be placed upon said collar log.

At approximately 10,150 feet, as previously noted, there would be three marking elements, in the main marking device 12a. The upper element 24a in this group is of a material similar to that used in the marker 12, and thus primarily affects the collar log 50 so as to produce a marking 58. The middle element 24b in this group is of a material that produces a different response at the ground surface, and that primarily ailects the correlation curves 46, 48, as shown at 62, 64, respectively in FIGURE 9.

The element 24C, in the marker 12a, being of the same material as the

elements

24, 24a, would primarily affect the collar log 50 to produce a marking 60, the markings 58, 60 of the collar log being disposed in anking relation to the deviations or pronounced

indentations

62, 64 produced in the correlation curves 46, 48 respectively.

The lower marker 12 contains an element 24, and, therefore, primarily aiects the collar log 50 to produce marking 56.

Other arrangements can -obviously be employed. One could produce markings on the colla-r log, at regular intervals over the full length of the same, which intervals might be greater than the intervals between adjacent casing collar markings 52. Then, rnain markings could be produced both on the collar l-og and on the correlation curves, as shown at 58, 60, 62, 64, through the use of the main marking devices 12a.

Referring now to FIGURE l0, there is here shown a typical employment of the method and means constituting the present invention. A conventional perforating device generally designated 66 i-s provided with perforating jets, bullets, or the like, as at 68. Said device is lowered into the casing by means of a wire line or suspension cable 70, which is designed to constitute a combination transmitting, conductor, and hoisting cable. At 72 I have generally designated a collar and/ or marker locator. This, like the perforating tool 66, is of conventional design.

Of course, the perforating gun is merely exemplary of one type of apparatus that might be lowered into the well casing along with the collar locator or other logging tool 72.

The upper dotted line showing of the

tools

72, 66, represents the approximate positions thereof when correlating or recording the reaction to the upper casing marker 12. The collar locator 72, in these circumstances, is directly abreast 4of said upper marker 12.

In these circumstances, through a lead 74 extending from the collar locator to` the yground surface, there is produced a reaction in a potential difference indicator 78, connected in series with recording and ground 82. 'Ihe upper marker 12 thus serves as a ydatum or reference point, to check the wire line accuracy. The attached collar locator 72 and perforating device 66 are now lowered to the lower dotted line position in FIGURE 10. This is 'done without loss of time, due to the use of the marker 12 as a datum point for checking the accuracy of the wire line. No necessity of lowering the equipment to the bottom Iof the well exists. On movement of the perfo-rating device to the exact position desired, abreast `of a producing formation D, the projectiles carried thereby are tired, by closure of a switch 86 which is normbally yopen in a lead 76 extending from the perforating device. A source of power 84 is provided in this circuit, having one terminal connected to ground as at 88.

Referring now to FIGURE 1l, there is here shown the lower portion of the well bore. By way of example, I have illustrated a collar locator 72 secured to a logging device 90. The logging device is located abreast of the marker 12a. The middle marker element 24h of the marking device 12a contains radioactive material, and a response is produced in the logging tool, which is graphically translated into deviations such as shown at 62, 64, in FIGURE 9.

The normal procedure during logging operations is to lower the logging tool 90 fully to the bottom of the well or the deepest depth to be logged. Then, the well is logged as the tool is moved upwardly out of the hole.

However, as the tool is being lowered into the hole, periodic checks and corrections must be made to compensate for deviations such as stretch, weight, temperature, etc., in the transmitting, conducting, and hoisting cable 70.

When a well having casing markers attached to the casing string in accordance with the invention is to be logged, a log similar to that shown in FIGURE 9 should be obtained. As the collar locator, with the logging tool 90 attached, moves upwardly, the collar locator will produce the deviations or

markings

56, 60, 58, and 54, due to the fact that the collar locator in this instance is sensitive to magnetic material, with the

elements

24, 24a and 24C being of permanent magnet material. The logging tool, meanwhile, is sensitive to radioactive material, and thereby produces the

deviations

62, 64, as it passes the element 24b.

This will complete preparation of the log shown in FIGURE 9, and said log is thereafter available during any operations to be performed in the well, whether they be perforation operations or some other type of wire line activities. For that matter, the invention is usable to equal advantage when operations other than those involving wire lines are being carried out.

One example of the use of the device, after completion of the log, is shown in FIGURE l and has previously been described herein.

It will be understood that the casing markers could be used in liners as well as on casing strings. Accordingly, the reference to a well casing is to be considered as embracing liners. Liners, in the nal analysis, are merely smaller strings of casing which are run or positioned in open-hole sections after the regular casing string has been inserted. Said open-hole section might be drilled after the regular casing string has been placed in the well bore. The liner is then lowered, through the casing string previously inserted, into the open-hole section.

It will be further noted that the device could be made as part of a conventional casing coupling. In this type of arrangement, the principles of the invention as abovenoted would be retained, but the device would be threaded and actually run as part of the casing string.

It is believed apparent that the invention is not necessarily confined to the specific use or uses thereof described above, since it may be utilized for any purpose to which it may be suited. Nor is the invention to be necessarily limited to the specific construction illustrated and described, since such construction is only intended to be illustrative of the principles of operation and the means presently devised to carry out said principles, it being considered that the invention comprehends any changes in construction that may be permitted within the scope of the appended claims.

What is claimed is:

l. In a device for speeding the positioning of apparatus in a well casing at a desired depth, and for promoting accuracy in said positioning, an improved casing marker for use in association with a sensing instrument capable of being lowered into said casing, comprising: arcuately curved marker means for producing in a sensing instrument a response recordable at ground level when said instrument is lowered into a well casing in juxtaposition to said means; a support for said means shaped as -a sleeve proportioned to encircle a well casing, and formed with an inwardly -facing recess complementing and receiving said means with said means substantially liush with the inner |bore of the sleeve; and means for mounting the sleeve on an imperforate portion of the casing at any of a plurality of selected locations along the length of the casing.

2. In a device for speeding the positioning of apparatus in a well casing at a desired depth, and for promoting accuracy in said positioning, an improved casing marker for use in association with a sensing instrument capable of being lowered into said casing, comprising: arcuately curved marker means for producing in a sensing instrument a response recordable at ground level when said instrument is lowered into a well casing in juxtaposition to said means; a support for said means shaped as a sleeve proportioned to encircle a well casing, and formed with an inwardly facing recess complementing and receiving said means with said means substantially flush with the inner bore of the sleeve; and clamping collars extendible about said casing and clampingly engageable therewith and disposed at opposite ends of said support so as to j casing, said collars being adapted for mounting the support on an imperforate portion of the casing at any of a plurality of selected locations along the length of the casing.

3. In a device for speeding the positioning of apparatus in a well casing at a desired depth, and for promoting accuracy in said positioning, an improved casing marker for use in association with a sensing instrument capable of being lowered into said casing, comprising: a plurality of concentrically curved, angularly spaced marker elements adapted for producing in a sensing instrument a response recordable at ground level when said instrument is lowered into a well casing in juxtaposition to said elements; a support for said elements shaped as a sleeve concentric with said elements, said sleeve being proportioned to encircle a well casing and being formed with internal recesses complementing and receiving said elements; and clamping collars extendible about said casing and clampingly engageable therewith and disposed at opposite ends of the support so as to constitute abutments limiting the support against movement from a selected location along the length of the casing, said collars being adapted for mounting the support upon an imperforate portion of the casing at any of a plurality of selected locations along the length of the casing.

4. In a device for speeding the positioning of apparatus in a well casing at a desired depth, and for promoting accuracy in said positioning, an improved casing marker for use in association with a sensing instrument capable of being lowered into said casing, comprising: at least two diametrically opposed, concentrically curved marker elements adapted for producing in a sensing instrument a response recordable at ground level, when said instrument is lowered into a well casing in juxtaposition to said elements; a support for said elements shaped as a sleeve concentric with the respective elements, said sleeve being proportioned to encircle a well casing and being formed intermediate its ends with diametrically opposed, internal recesses complementing and receiving the respective elements, said elements having confronting, arcuately concave, inner faces flush with the inner surface of the sleeve when the elements are engeged in the respective recesses; and clamping collars extendible about said casing and clampingly engageable therewith and disposed at opposite ends of the support so as to constitute abutments limiting the support against movement from a selected location along the length of the casing, said collars being adapted for mounting the support upon an imperforate portion of the casing at any of a plurality of selected locations along the length of the casing.

5. In a device for speeding the positioning of apparatus in a well casing at a desired depth, and for promoting accuracy in said positioning, an improved casing marker for use in association with a sensing instrument capable of being lowered into said casing, comprising: at least two diametrically opposed, concentrically curved marker elements adapted for producing, iu a sensing instrument, a response recordable at ground level when said instrument is lowered into a well casing in juxtaposition to said elements, said elements having arcuately convex outer faces formed with threaded sockets; a support sleeve for said elements concentric with the respective elements, said sleeve being proportioned to encircle a well casing and being formed intermediate its ends with diametrically opposed, internal recesses complementing and receiving the respective elements, said elements having confronting, arcuately concave, inner faces flush with the inner surface of the sleeve when the elements are engaged in the respective recesses, the sleeve having radial openings aligned with the respective sockets and communicating between the recesses and the outer surface of the sleeve; threaded fastener members extending through said openings and engaged in the sockets to connect said elements to the sleeve; and clamping collars extendible about said casing and clampingly engageable accuracy in said positioning, an improved casing marker for use in association with a sensing instrument capable of being lowered into said casing, comprising: at least two diametrically opposed, concentrically curved marker elements adapted for producing, in a sensing instrument, a response recordable at ground level when said instrument is lowered into a well casing in juxtaposition to said elements, said elements having arcuately convex outer faces formed with threaded sockets; a support sleeve for said elements concentric with the respective elements, said sleeve being proportioned to encircle a well casing and being formed intermediate its ends with diametrically opposed, internal recesses complementing and receiving the respective elements, said elements having confronting, arcuately concave, inner faces flush with the inner surface of the sleeve when the elements are engaged in the respective recesses, the sleeve having radial openings aligned with the respective sockets and communicat-V ing between the recesses and the outer surfaces of the sleeve; threaded fastener members extending through said openings and engaged in the sockets to connect said elements to the sleeve; and clamping collars extendible about said casing and clampingly engageable therewith and disposed at opposite ends'of the sleeve so as to constitute abutments limiting the sleeve against movement from a selected location along the length of the casing, each of said collars including a radially contractible, arcuate collar member having spaced ends formed with oppositely threaded recesses, each collar further including a stud having threads .of opposite hand at its respective ends, said studs being engaged in the lastnamed recesses for contracting the collar member to the well casing responsive to rotation of the studs, thus to mount the'sleeve upon an imperforate portion of the casing at any of a plurality of selected locations along the length of the casing, said fastener members and studs being disposed wholly interiorly of the outer circumferences of the sleeve and collar members.

References Cited in the le of this patent Marquis et al L..-" Feb. 14, 1956

Claims

1. IN A DEVICE FOR SPEEDING THE POSITIONING OF APPARATUS IN A WELL CASING AT A DESIRED DEPTH, AND FOR PROMOTING ACCURACY IN SAID POSITIONING, AN IMPROVED CASING MARKER FOR USE IN ASSOCIATION WITH A SENSING INSTRUMENT CAPABLE OF BEING LOWERED INTO SAID CASING, COMPRISING: ARCUATELY CURVED MARKER MEANS FOR PRODUCING IN A SENSING INSTRUMENT A RESPONSE RECORDABLE AT GROUND LEVEL WHEN SAID INSTRUMENT IS LOWERED INTO A WELL CASING IN JUXTAPOSITION TO SAID MEANS; A SUPPORT FOR SAID MEANS SHAPED AS A SLEEVE PROPORTIONED TO ENCIRCLE A WELL CASING, AND FORMED WITH AN INWARDLY FACING RECESS COMPLEMENTING AND RECEIVING SAID MEANS WITH SAID MEANS SUBSTANTIALLY FLUSH WITH THE INNER BORE OF THE SLEEVE; AND MEANS FOR MOUNTING THE SLEEVE ON AN IMPERFORATE PORTION OF THE CASING AT ANY OF A PLURALITY OF SELECTED LOCATIONS ALONG THE LENGTH OF THE CASING.