US2120670A - Method and apparatus for orienting tools - Google Patents

Description

R. s. HYER METHOD AND APPARATUS FOR ORIENTING TOOLS June 14, 1938.

Filed-July s, 1935' Patented June 14, 1938 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR OBIENTING TOOLS Robert S. Hyer, Houston, Tex, assignor to Sperry-Sun Well Surveying Company, Philadelphia, Pa., a corporation of Delaware Application July 5, 1935, Serial No. 29,896

8 Claims. lei. 255-1) As is well known, many wells, particularly those produced by rotary drilling, deviate very considerably from the vertical at even moderate 10 distances from the surface, such deviations being apparently due to lack of uniformity in the soil through which the drill is passing, and being particularly noticeable in the case of rotary drilling, since the rotation of the drill stem appears to promotethe production of a tortuous hole. If a bore hole deviates to a substantial degree from the vertical, it may entirely miss the locality which is believed tocontain oil. Once a bore hole begins todeviate from the vertical, little can be done in the way of control of the drilling from the surface to cause it to become vertical. Accordingly, it is the practice to insert within the borehole a whipstock having a guiding surface at an angle with the axis of the bore hole to direct the drill in the desired direction to reach its objective. Obviously it is necessary to properly orient the whipstock to insure that a proper correction of the direction of the bore hole will be made.

The orientation of whipstocks is also useful where it is desired to direct a bore hole'in a predetermined direction, as may occur, for example, where the derrick cannot .be conveniently set up directly over the point which it is desired that the bore hole should reach. In such cases, the

hole may be started from the surface at a laterally displaced location and may be deflected by means of oriented whipstocks to cause it to finally arrive at the desired point.

40 The orientation ofa whipstock necessarily involves, a knowledge of the path of a borehole so that a preliminary survey must be made to find direction and position of the lower end of the hole.

Various methods of orienting whipstocks are known, a typical one being described in the transactions of the Institute of Mining and Metallurgy (1911-1912, pages 481 to 489). Car- I -rying out any of the known processesis quite diillcult by reason of the various manipulations involved, so that they are impractical.

It/is the object of the present invention to provide a method and means whereby a whip-.

- stock may be lowered upon a hollow'drill stem, 65 without the necessity for carrying out drill stem orientation, and its position determined, the drill stem rotated to bring it into a predetermined azimuthal position, the position" checked, and the whipstock then set and released from the drill stem. While the invention has been and 5 will be described particularly with reference to whipstock setting, it will be clear that the invention isv applicable to the proper orientation of any other tool which is to be located in a predetermined azimuthal position in a bore hole. 10

Detailed objects of the invention will be apparent from the following description read in conjunction with the accompanying drawing, in

which: r

Fig. 1 is a sectional view showing a drill stem 15 supporting a whipstock and having located therein a position checking instrument;

Fig. 2 is an enlarged fragmentary sectional view of the position checking instrument;

Fig. 3 is a plan view of a photographic record 2 made by the use of thepreferred type of instrument; and

Fig.4 is a fragmentary view showing a possible modification of a portion of the checking instrument if the whipstock is being oriented where 25 the slope of the bore hole deviates substantially from the vertical. 7

In carrying out the improved method, it is first necessary to make a complete directional survey of the bore hole. This should be done by 30 the use of 'an instrument which is not subjected to tortuosity errors. Both gyroscopic and magnetic instruments would satisfy the requirement for avoidance of errors due to tortuosity, but the only type of instrument which is fully reliable is 3 a gyroscopic one, due to the errors caused in magnetic readings by mineral deposits or the presence of magnetic bodies artificially present in the bore hole. An accurate survey with no errors due to tortuosity or magnetism may be 40 made by the type of instrument described in the patent to Williston and Nichols, No. 1,960,088, dated May 22, 1934. This instrument photographically records the position of a gyroscope and bubble at short intervals of time corresponding to rel- 45 a atively short distances along the path of a bore hole. Such instrument may be lowered either on a wire line or a drill stem for the purpose of making the initial survey.

In general, magnetic instruments are fairly 60 satisfactory for app oximate results. Magnetic compasses are usually sufilciently accurate, since usually only slight local disturbances of the earth's magnetic field, it any, occur, to permit the setting of whipstocks to a degree of accuracy which can be expected of the results of the whipstock in deflecting a drill. Accordingly, although for the initial survey a gyroscopic instrument is most desirable since it will determine to a high degree of accuracy the actual path of the bore hole, nevertheless there is employed, in accordance with this invention, the indication of a magnetic compass to determine the position of the whipstock. If the hole, however, has a substantial slope from the vertical where the whipstock is being set, the indication of azimuthal position independent of any magnetic disturbing influence may be determined by means of a modification of the checking instrument described herein. Such instrument, however, gives indeterminate results where the bore hole is vertical. I

Referring to Figs. 1 and 2, there is illustrated therein a drill stem 2 the lower portion of which takes the form of a non-magnetic catcher 4 to which there is secured, in any conventional fashion, a whipstock or other tool 6. This connection may take the form, for example, of a rivet which may be sheared when it is desired to fix the whipstock in final position in the bore. The whipstock may be of any suitable type de signed to be finally held in position either by penetration of the soil or by cementing.

An instrument designed to indicate the position of the whipstock is arranged to be lowered into the non-magnetic catcher 4. This instrument may comprise an outer protective casing 8 carried by a line l0. Within the protective casing 8 is the instrument proper I2 which is illustrated in detail in Fig. 2. The instrument contains a pair of magnetic compasses and consequently it must be of non-magnetic construction to the extent of any parts which might affect the readings. This remark applies to the protective casing and the lower portion of the suspension means which may consist of a spacer between the casing and suspension line proper. The catcher 4 and any associated parts, for example, between it and the whipstock, must be non-magnetic to a sufiicient extent beyond the compasses so that their readings will not be afiected. The nonmagnetic catcher 4, however, carries a permanent magnet 48 arranged to cooperate with the lower compass, this magnet being sufiiciently powerful so that the effect of the earths field on the lower compass is negligible. This permanent magnet preferably takes the form of a threaded screw which can be inserted into a drilled and tapped hole in a non-magnetic catcher. It is made removable so that it can be re-magnetized if it loses its magnetism.

One form of the position recording instrument is illustrated in Fig. 2. This instrument is provided with a sidewise opening slot into which there may be inserted, and from which there may be extracted, a sensitized film disc Hi. This disc comprises sensitized celluloid or other transparent or translucent material, preferably reinforced at its edges by a metallic ring. A threaded lower support l8 may be rotated and thereby axially moved by a knob 20 to uncover the slot l4 so that the film may be dropped in place from a light-tight receptacle through a light-tight connection with the slot. the knob 20, the supporting member l8 moves upwardly, closing off the slot and causing the film disc I8 to contact with a ring 22 which locates it in proper focal relationship to the camera lenses 24 and 36.

The former lens 24 is designed to project upon Upon reverse movement of the film an image of the lower indicia carrying surface of a compass float 28 guided by a vertical wire 28 in a chamber 30 containing a damping liquid, which chamber is provided with a glass remote from any disturbing influences. Errors in,

the reading of this compass can only be due to errors occasioned by disturbances of the earth's magnetic field due to ores or the like. Such disturbances are, in general, relatively small, and considering the fact that a whipstock can only deflect a drill bit in a predetermined direction within certain limits of,'error, the indications of a compass of this type are sufiicient for the present purpose. The compass is illuminated by bulbs 34, which, together with other bulbs 42, are energized at suitable times.

The lower lens 38 projects upon the film the image of a lower compass 38 contained within a glass topped chamber 40. -The bottom of the chamber forms a light-tight closure between the upper and lower portions of the instrument. The bulbs 42 are designed to illuminate the compass 38, one end of which may be differentiated from the other-end by difierence in light reflecting properties. The compass 38 need not be very delicately mounted, since this compass is designed to be affected by the strong magnetic field of the permanent magnet 48.

Located below the compass 38 and accessible through anjopening in the side of the instrument is a time switch 44 of any conventional type which is designed to be set so that a predetermined time will elapse after setting before the circuit through the lamps 34 and 42 is closed. The

' switch then maintains the circuit closed for a suflicient period to produce an exposure and thereafter breaks the circuit with the result that a single exposure of a particular film I 8 will be produced, giving a superimposed picture of the indications of the two compasses. Current for operating the lamps may be supplied by batteries contained in the lower portion 43 of' the instrument.

The type of reoordwhichis produced is indicated in Fig. 3, which illustrates the disc it after development. The markings 21 are those produced by the upper compass 26, while the marking 39 is produced by the lower compass 38. I

Inxcarrying out the improved method, there is located within the instrument a sensitized film l6 and when the instrument is ready for lowering, the time switch 44 is set so that the exposure will not be made until the instrument is in its final position. The instrument in its protectivet casing is then lowered into the drill stem, which carries the whipstock at the vertical location where it is to be fixed. When the instrument reaches the bottom of the drill stem and rests in its final position within the catcher 4, the lower compass 38 will be located directly opposite the permanent magnet 48, which consequently will hold it in a fixed position. Since the position of the magnet 48 relative to theface of the whipstock will have been previously noted, it will be clear that the compass 38 will occupy a predetermined position relative to the whipstock.

At the same time, when the instrument is in its lowermost position, the compass 28 will be located away from disturbing influences in the non-magnetic catcher and will attain a position determined by the direction of the earth's magnetic field. v

The instrument is permitted to remain in its lowered position until the time for making an exposure has expired and is then drawn to the surface, opened, and the sensitized disc withdrawn and developed; From the superimposed images of'the two compasses, the azimuthal position of the whipstock may be directly determined and the drill stem may then be rotated a suificient amount to bring the whipstock into a predetermined position. In so rotating the drill stem, it is desirable to move it up and'down to avoid frictional drag on the lower end, which might cause the lower end to be rotated through an angle less than the predetermined angle of rotation of the upper end. Before finally fixing the whipsto'ck in position, the instrument l2 may be again lowered with a second film and exposure made, and

.from the preliminary survey, giving the direction of slope of the bore hole where the whipstock is being set. A modified type of apparatus for this purpose can be provided by substituting the parts indicated in Fig. 4 for the upper part of the instrument indicated in Fig. 2. This substitution consists essentially of a box level containing a bubble 52 for the compass 26. The image of the bubble is i'ocussed by the lens 24', corresponding to lens 24, upon the film through the glass bottom of the box level, the bubble being illuminated by lamps 34' corresponding to 34. The cover or the box level may, if desired, be marked with indicia showing the central point.

From the superimposed records of the bubble and lower compass fixed by the permanent magnet, and from the preliminary survey data, it is obvious that the azimuthal position of the whipstock may be ascertained, since the direction represented by the relationship of the image of the bubble to the center of the film is dependent upon the direction of maximum inclination given by the preliminary survey data. nary survey was made with an accurate gyroscopic instrument, it is obvious that the location of the positioncf the whipstock will be entirely independent of any irregularities of the earths'magnetic field; The only failure of the type of arrangement illustrated in Fig. 4 occurs when the bore hole is so nearly vertical that the direction of the bubble relative to the center position cannot be ascertained .with any degree of accuracy. The ease oi determining this to a. high accuracy increases, of course, with the deviation of the bore hole from the vertical. If

a level indicator, such as the illustrated bubble,'

or an equivalent pendulum or the like, is used for indicating the azimuth, it is, of course, unnecessary to provide a non-magnetic catcher. It

would only be necessary to provide non-magnetic parts immediately surrounding the permanent magnet 4l so that its field could influence the lower compass.

If the prelimi- Patent is:

1. The method of orienting a tool within a bore hole including lowering the tool into the bore hole on a hollow drill stem, the lower portion; of

' which drill stem carries a magnet, lowering within the drill stem an instrument containingmeans for indicating azimuth, a magnetic-compass, and

means for recording the indications of the azimuth indicating means and the' compass, said lowering of the instrument being to a point where the compass is closely adjacent said magnet whereby the compass assumes a I predetermined position relative to the magnet; thereafter causing said recording means to operate; withdrawing said instrument; and rotating the drill stem to bring the tool into a predetermined azimuthal position.

2. The method of orienting a tool within a bore hole including lowering the tool into the bore hole on a hollow drill stem, the lower portion of which drill stem has a non-magnetic section and carries a magnet; lowering within the drill stem an instrument containing a pair of magnetic compasses, and means for recording the indications of said compasses, said lowering of the instrument being to a point where one of the compasses is closely adjacent said magnet where-. by it assumes a predetermined position relative to the magnet, and where the other compass is located in the non-magnetic section of the drill stem and is spaced from said magnet whereby it responds solely to the earth's magnetic field;

thereafter causing said recording means to operate; withdrawing said instrument, and rotating the drill stem to bring thetool into a predetermined azimuthal position.

8. In combination, a hollow drill stem; a tool carried by the drill stem; an instrument arranged 'to pass through the drill stem and arranged to occupy a predetermined final longitudinal position therein adjacent the tool, said instrument containing means for indicating azimuth, a magnetic compass, and means for recording the indications of the azimuth indicating means and the compass; and a'magnet carried by the drill stem in a position in the immediate vicinity of said compass when the instrument is in said final potive to the instrument.

' 4. In combination, a hollow drill stem'having a non-magnetic lower section; a tool carried by the lower end of the drill stem; an instrument arranged to pass through the drillstem and arranged to occupy a predetermined final longitudinal position in said non-magnetic lower section, said instrument containing a pair of magnetic compasses, and means for recording the indications of said compasses; and a magnet carried by the drill stem in a position in the immediate vicinity of one of said compasses when the instrument is in said final position whereby the last sition whereby said compass is caused to give an' indication of the position. of the drill stem relastrument.

5. The method of orienting a tool within a bore hole includinglowering the tool into the bore hole or'ia hollow drill stem, the lower portion of which drill stem carries a magnet, lowering within the drill stem an instrument containing means for indicating azimuth and a magnetic compass, said lowering of the instrument being to a point where the compass is closely adjacent said magnet whereby the compass assumes a predeterpass, and means for recording the indications 'of the azimuth indicating means and the compass, said lowering of the instrument being to a point where the compass is closely adjacent said magnetic element whereby the compass assumes a predetermined position relative to the magnetic element, thereafter causing said recording means to operate, withdrawing said instrument, and rotating the drill stem to bring the tool into a predetermined azimuthal position.

7. The method of orienting a tool within a bore hole including lowering the tool into the bore hole on a hollow drill stem, the lower portion of which drill stem carries a magnetic element, lowering within the drill stem an instrument containing means for indicating azimuth and a magnetic compass, said lowering of the instrument being to a point where the compass is closely adjacent said magnetic element whereby the compass assumes a predetermined position relative to the magnetic element, thereafter determining the relative indications of the azimuth indicating means vand compass, withdrawing said instrument, and rotating the drill stem to bring the tool into a predetermined azimuthal position.

8. In combination, a hollow drill stem; a tool carried by the drill stem; an instrument arranged to pass through the drill stem and arranged to occupy a predetermined final longitudinal position therein adjacent the tool, said instrument containing means for indicating azimuth, a magnetic compass, and means for recording the indications of the azimuth indicating means and the compass; and a magnetic element carried by-t'he drill stem in a position inthe immediate vicinity of said compass when the instrument is in said final position whereby said compass is caused to give an indication of the position of the drill stem relative to the instrument.

I ROBERT S. HYER.

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