US2329732A - Signaling deviation detector - Google Patents

Description

Sept. 21, 1943.

F. M. VARNEY ETAL SIGNALING DEVIATION DETECTOR Filed Sept. 8, 1941 2 Sheets-Sheet 1 MEE@EEtEEE l I I A Tmp/Vf Ks.

' Sept. 2l, 1943. F. M. VARNEY ET AL SIGNALING DEVIATION DETECTOR Filed Sept. 8, 1941 2 Sheets-Sheet 2 .H w mae/MM D .K m o fr E adm rm f, d/

Patented Sept. 2l, 1943 orifice.

SIGNALING DEVIATION DETECTOR Fred M. Varney and Justin Arnold Varney.

' Los Angeles, Calif. i

Application September 8, 1941, Serial No. 409,989

12 Claims.

Our invention relates to the art of ascertaining and indicating deviations from vertical voi a well bore and is applicable to Well surveying devices in general. Since it is contemplated that the present invention will nd immediate application in devices that may be .incorporated in a string of drill pipe to serve as a deviation-warning means for the convenience of a driller, the

present disclosure will be confined to embodiments of such character, but it is to be understood that our invention is not to be restricted to any narrow class of well surveying apparatus.

'I'he present invention is an improvement on the signaling clinograph set forth in our copending application, Serial No. 316,196, entitled Signaling clinograph, and shares the same objects.

\ In the prior device anessential portion of the signaling mechanism was in the form of a special channel member separate and apart from the major portion of the device and separately mounted in the drillA pipe, the function of the separate portion being to cooperate in repeatedly restricting the stream of drilling uid for the purpose of generating signal Waves therein. One of the objects of the present invention is to provide a self-sufficient signaling apparatus that may be lowered bodily into a string of drill pipe, there being no necessity whatsoever for withdrawing the drill pipe to install special equipment.`

Another object of the invention relates to the control of a signal or indicating mechanism by a pendulum member or other gravity-responsive member that stops the mechanism at Various points in an operating cycle in accord with various angles of deviation detected by the gravityresponsive member. The problem involved is to provide a time interval for the gravity-responsive member to become stable prior to functioning as a stop. Fluid action may be relied upon to retard or otherwise contro1 the rate of action of the signal or indicating mechanism, but, if so, a second problem arises in that variations of viscosity of the iiuid attributable to temperature changes or other factors ordinarily cause correspending variations in the control eiect. In this aspect, an object of our invention is to provide a solution for both of these problems, the solution including the provision of a dash-pot and the provision of a sharp-edged orice in the dash-pot arrangements to minimize the effects of viscosity variation.

Certain diiliculties in designing devices of the present characterV relate to the manner oi mounting or supporting a gravity-responsive member. To aiord sensitivity it is requisite that the bearings freely permit oscillation of the pendulum or other gravity-responsive device. hence friction surfaces should be of minimum area and well lubricated with no tendency whatsoever to stick; yet the bearing must be sturdy and capable of functioning through long operating periods without loss in eiiiciency and without delays for servicing or inspection. Ii.' the invention is to be used in a drill string, itis especially diflcult to achieve these ends because the apparatus is continually subject to severe vibration and shock in the course of drilling operation. Ball-and-socket pendulum bearings have been used-heretofore, but therelatively extensive friction surfaces required to make such `bearings sturdy do not favor sensitive action. especially so because ball-and-socket surfaces are not easily lubricated and tend to become so gummy as to stick. The spherical surfaces of such a bearing. moreover, tend to wear out; of round under the continual pounding of drilling operation. To minimize this latter tendency, provision may be made to continuously stress the ball-and-socket bearing whenever the pendulum is out of service thereby to relative movement between cooperating bearing members during drilling operation, but such expedients and refinements have not resulted in satisfactory bearing structures.

One group of objects of our invention relates to these various difliculties in bearing design. These objects include the following: to provide a bearing with minimum areas of friction eiective during detection operation; to 4provide for substantially one-point support of the gravity-responsive member during detection operation; to provide for automatically ushing VwithV lubricant all bearing surfaces prior to detection operation; to provide for shifting all possibilities for wear to non-bearing surfaces during drillingroperation; and to completely separate the bearing surfaces during drilling operation. Y A

The above and other objects of our invention will be apparent in lour detailed description to follow, taken with the accompanying drawings.

In the drawings, which are to' be considered as illustrative only,

Figs. 1 to 4 in sequence represent a longitudinal section through the preferred form` of our apparatus, a small portion being shown in side elevation in Fig. 4;

Fig. 5 is an enlarged detail of Fig. 3;

Fig. 6 is a transverse section on an enlarged scale taken as y,indicated by the line 6-6 of Fig. 4; and

Fig. 7 is a fragmentary longitudinal section on an enlarged scale taken as indicated by the line '|-1 of Fig. 4.

The device shown in the drawings is adapted to be lowered into a drill string to come to rest in the lower portion of the drill string comprising the usual drill collar or sub. In Figs. 1 to 4 dash-dot lines indicate the inner cylindrical wall I of the drill string, a transverse face or shoul- V`der II (Fig. 4) at the lower end of the drill string,

and a passage I2 to conduct the downwardly flowing drilling mud to the rotating bit below.

The principal parts of the preferred form of the invention shown in the drawings are: an instrument case in the form of a cylinder generally designated I5; a. iiuid-passage means generally designated I6, the uuid-passage means being united with the case I5 by spaced arms I'I to constitute what may be termed a unitary housing assembly; a gravity-responsive deviation detector in the form of a pendulum I8 of non-magnetic material inside the case; and what may be termed a plunger assembly generally designated 2D that extends through the upper end of the case I5 and carries an external plunger head 2 I. Normally, that is to say during routine drilling operation, the plunger assembly is in a lower or retracted position by virtue of the velocity head of the downwardly iiowing drilling mud acting against the plunger head 2|.

If the mud pumps at the surface of the well are stopped to interrupt the downward flow of the drilling iiuid, a helical spring 22 in the case I5 (Figs. 3 and 4) becomes eiiective to force the plunger assembly 20 upwardly into progressive extension into the duid-passage means I6, and the pendulum I8 carried upwardly by the plunger assembly controls the extent of the upward plunger-assembly movement in accord with the deviation of the case I5 from vertical. The desired control is achieved by providing the pendulum I8 with an upwardly presented annular stop shoulder 23 and providing the inner cylindrical wall of the case I5 with a series of downwardly presented stop shoulders 24, 25, 26, 21, 28, and 29 designed for cooperation with the stop shoulder 23 on the pendulum, the stop shoulders 24-28 being arranged in a progressively constricted series with respect to inside diameters to cause the permitted range of movement of the plunger assembly 2|! to be varied in a predetermined manner in accord with the degree of deviation from vertical. In the particular arrangement shown, onlyl a relatively short upward movement of the plunger assembly 20 is permitted if the cylinder I 51is tilted beyond a predetermined maximum angle from vertical and a maximum extent of upward movement of the plunger assembly is permitted if the cylinder I5 is vertical within a. predetermined tolerance of small magnitude.

When the mud pumps at the surface of the well are subsequently placed in operation to restore downward iiow of the drilling stream through the drill string, the impingement of the either the plunger head 2| or the passage means I6 is formed with an alternately expanded and contracted configuration. In the present construction the uuid-passage means I6 is alternately enlarged and reduced in internal diameter so that the plunger head 2| in moving downwardly therethrough intermittently chokes the fluid flow. Since the extent of the upward movement of the plunger assembly 20 is determined by the inclination of the case I5 relative to the pendulum I8, the number of times the plunger head 2| cooperates with the fluid-passage means I6 to restrict the stream of drilling iluid will vary with the instant degree of deviation of the case I5 from vertical and the pressure waves sent to the surface of the well will. in effect, signal the degree of such deviation.

If the restricting action on the mud stream created by the plunger head 2| in cooperation with the fluid-passage means I6 is relatively sharp or severe, no special provision will be required at the surface of the well to make the signals perceptible. The waves may be clearly audible, or may be visually perceptible in movement of parts at the surface of the well, or may be recognized by simply touching the kelly or rotary hose. In any event, the pressure waves may be readily revealed at the surface by an ordinary pressure-responsive device such as a conventional pressure gauge. Any suitable type of automatic pressure recorder may be used if desired.

In the construction of a preferred form of the invention shown in detail in the drawings, the huid-passage means I6 includes a thin-walled cylinder 3D of nearly the same outside diameter as the internal diameter of the surrounding drilling string. Welded to the upper end of the cylinder 30 is a tapered sleeve 3| that carries a pair of external sealing rings 32, the sealing rings having the dual function of centering the housing assembly in the drill string and preventing downward flow of the drilling stream around the periphery of the fluid-passage means I6. Fixedly mounted inside the cylinder 30 is a series of uniformly spaced now-restricting rings 33 that give the interior of theV fluid-passage means I6 the alternately expanded and contracted configuration required for the desired cooperation with the plunger head 2 I.

The lower end of the cylinder 30 is welded to a tubular member 35 that is united with the upper end of the case I5, the tubular member having longitudinal slots 36 that form the previously mentioned arms I'I and permit iiuid nowing downwardly through the duid-passage means I6 to pass outwardly around the case I5. The case I5 is substantially smaller in outside diameter than the interior of the surrounding drill string. V/H

The case I5 is rfill/d with a suitable instrument uid such as light oil and may be made in three sections threaded together: an upper section 40 (Fig. 2), a middle section 4I and a lower section 42 (Fig. 4). The lower section 42 of the case I5 is seated in and secured to a. support member 43 that has four radially disposed wings 45, the wings having the dual function of centering the lower end of the case I5 and supporting the lower end of the case above the entrance to the iiuid passage I2 to avoid blocking fluid iiow into the passage.

The plunger assembly 2U includes an upper plunger rod 46 carrying the plunger head 2|, an intermediate piston 4l, and a lower plunger rod the middle section 8| to retain a guide bushing 5| for the upper plunger rod 46 and a sealing ring -r 52. The sealing ring 52 .serves to prevent ow around the outside of the guide bushing into the case l5 below the guide bushing. but an inner longitudinal groovev 53 permits the instrument fluid to ilow through the guide bushing along the plunger rod 96. A diaphragm or sleeve 55, which may have the general conguration of a bellows, embraces the plunger rod 46 at its upper end in a uid-tght manner and likewise at its lower end embraces in a fluid-tight manner a neck 5S formed by the guide bushing 5|. The diaphragm 55, which is made of rubber or material of similar character; may be regarded as a ilexible wall of the case I5 or may be considered as forming a chamber 5l of variable volume that is -in communication with the case proper through the passage 53 in the guide bushing 5| to permit liquid displacement through the guide bushing occasioned by longitudinal movement of the plunger assembly 29.

One object of the particular form of the invention shown in the drawings is to avoid any poswith an outer annular shoulder 83. The previunder side oi the piston 41.

sbility ofthe pendulum I8 being placed under excessive tension attributable to reverse or upward ow of the drilling stream against the under surface Vof the plunger head 2|. This object is attained by breaking the plunger assembly 20 into two sections that simply separate if any anomalous reverse ilow of the drilling fluid occurs. The point of separation may have various v locations, but in the present arrangement is placed at the juncture of the upper plunger rod 46 and the piston 41. The lower end of the plunger rod 46 is threaded into a. cylindrical guide 58 that normally rests against the upper face of the piston 41, fluid access to the upper face of the piston being provided by a series of longitudinal bores 60 through the cylindrical guide and by a central recess 6| on the under side of the cylin-l drical guide.

, rod 48, a radial bore 68 in the plunger rod, a peripheral recess 'l0 in the plunger rod, and a pair of radial passages 1| in the tubular extension 63 of the piston.

.suitably fixed inside the instrument case l5 well below the range of reciprocation of the'piston 4l' is a thin-walled sleeve 'I2 having its lower edge beveled to form the previously mentioned lowermost stop shoulder 24. Arranged in succession above the sleeve 12 are additional sleeves 13, 16, 15, and 16 that likewise have lower beveled edges to form the corresponding stop shoulders 25-28. Resting lon top of the described series of sleeves is a tubular member 80 equipped with a hardened guide bushing 8| for the plunger rod 48, the lower beveled edge of which bushing serves `also as the uppermost stop shoulder 29. The tubular member 80 has an upwardly extendously mentioned spring 22 that continuously urges the plunger assembly 20 upwardly rests on the annular shoulder 83 and acts against the in the periphery of the sleeve 16, and four radial bores 88 in the sleevel 16 extending inwardly from the corresponding longitudinal grooves 8l. For

lincreased ilow capacity and to divide the inward iluid ow into several jets; the sleeve 15 immediately below the sleeve |8.may be formed with an annular groove 90 at its upper end, four longitudinal peripheral grooves 9| and four corresponding radial bores 92. The division of the inowing uid into numerousjets minimizes any ow eect that might tend to force the pendulum i8 out of vertical. Y

The lower section 82 of the instrument case provides a tapered entrance 93 to a deep cylindrical recess 95 in which the pendulum i8 is normally seated and held immobilized by pressure from the plunger assembly 20. A feature oi the present embodiment of the invention is that the bearing that pivotally supports the pendulum on the plunger assembly duringl a detecting operation provides for relative movement between the pendulum and plunger assembly whereby the bearing surfaces are completely separated when the pendulum is pressed into the recess 95 during normal drilling operations. Such an arrangement avoids any wear whatsoever of the bearing surfaces attributable to the vibration and shock of drilling.

To provide such a bearing a U-shaped stirrup 96-may be mounted on the lower end of the plunger rod 48 by means of a Vsuitable cross pin 97, as shown in Fig. 4, to carry a bearing mem- 96 and to present a bearing socket to receive the projection 98. l For example, as best shown in Fig. 7, the upper end of the pendulum may be formed with a pair of arms I 00 to receive the stirrup 96 and to carry a bearing member in the form of a small block |0| mounted between the arms by a suitable pin |02, the block having a downwardly presented socket |03. Preferably. the socket |03 is of conical conguration and the complementary projection 98 is of sharper conical conguration so that supporting contact is limited to the extreme tip of the projection and the deep center of the socket.

When the device is in a drill string during drilling operation with the plunger assembly 20 in a normal retracted position determined by the seating of the plunger head 2|, the plunger assembly confines the pendulum I8 in the Well 95.

' At such time the plunger assembly provides a tit into the surrounding well 95 to provide a damping dash-pot action.

To ascertain the instant deviation of the bore hole, if any, the operator ceases drilling rotation of the drill string and stops the mud pumps to terminate downward iiow of the drillingmud through the drill string, whereupon the plunger assembly 20 is urged upwardly by the spring 22 and the projection S8 enters the socket |03 to lift the pendulum I8 out of the recess S5, the bearing surfaces being well flushed by the instrument uid. The. incorporation of the diaphragm sleeve 55 in the combination permits the device to maintain a constant over-all volume as the plunger assembly rises and falls. As the plunger assembly rises, the instrument fluid flows out of the chamber 51 defined by the diaphragm 55 into the space below the guide bushing 5| by way of the passage 53 and simultaneously instrument uid ows from the upper side of the piston 41 to the lower side of the piston through the dash-pot passage that includes the sharpedged orice member 55.

The dash-pot arrangement serves several purposes: it retards the plunger rise enough to let the pendulum become stabilized at vertical alignment before the annular stop shoulder 23 on the lower end of the pendulum comes within the range of the lowermost stop shoulder 24 on the wall of the instrument case; it retards the plunger rise sufficiently to avoid any appreciable deflection of the pendulum by the drag of the instrument iiuid; it retards the retraction movement of the plunger assembly under pressure from the mud stream until the mud stream accelerates to a velocity adequate for generating a strong signal wave; it retards the retraction movement of the plunger assembly to provide adequate time intervals between the signal waves; it prolongs the duration of a pressure rise to insure detection by the operator at the surface of the well; and, by virtueof the sharpedged orifice, it minimizes any variation in the rate of movement' of the plunger assembly that may be attributable to variation in viscosity of the instrument uid with changing temperature and pressure.

If the stop shoulder on the pendulum engages one of the stop shoulders 2li-29, the plunger head 2| will terminate its upward movement at a corresponding one of the six positions |04| ||l shown in dotted lines in Fig. 1, and if the instrument case is so nearly vertical that the pendulum escapes all of the stop shoulders 24-29 the plunger head 2| will be carried to the upper limit position |10 in Fig. l. If the mud pumps are started after the plunger head 2| stops its upward movement at one of the dotted line positions, the velocity head of the mud stream will cause downward movement of the plunger assembly and a sharp pressure wave will be created in the mud stream as the plunger head 2| passes into each of the flow restrict-ing rings 33 and again when the plunger head enters the restriction provided by the tubular member 35.

The degrees of deviation represented by the various stop shoulders 24-29 may be spaced according to the closeness of control desired. For example, seven signals made possible by maximum upward movement of the plunger assembly may indicate a deviation from vertical of less than one-half degree; six signals resulting from the pendulum engaging the stop shoulder 29 may indicate a deviation of between one-half and one degree; five signals resulting from the pendulum engaging the stop shoulder 28 may indicate a deviation of between one and one and one-half degrees; four signals resulting from the pendulum engaging the stop shoulder 21 may indicate a deviation of between one and one-half and two degrees; three signals resulting from engagement of the pendulum with the stop shoulder 26 may indicate a deviation of between two and three degrees; two signals resulting from engagement of the pendulum with the stop shoulder 25 may indicate a deviation of between three and four degrees, and one signal resulting from engagement of the pendulum with the stop shoulder 2B may indicate a deviation in excess of four degrees. It will be noted that in any event the device will send at least one signal to the top of the well to indicate that it is functioning.

The plunger head 2| may be stopped by the various stop shoulders of the plunger at positions of maximum now between the various iiow restricting rings 33. In practice, however, we prefer to arrange for stopping the plunger head at the dotted positions ||l4||0 inside flow restricting rings, each position being in the restricting ring above the restricting ring that is to engender the first signal when the plunger subsequently moves downwardly. The purpose of stopping the plunger head inside a restricting ring instead of in the larger space below is to provide for a substantial extent o1 movement of the plunger prior to the first signal engendered by iiow restriction. An appreciable interval of time may be required for acceleration of the fluid stream when the mud pumps are started and the described arrangement provides for the required interval of time before the rst signaling pressure wave is created in the mud stream. A further reason for delaying the rst pressure sign al is that mud pumps commonly labor when rst started with consequent pounding that might be confused with signals of the deviation detector in the well.

The preferred form of our improvement described herein in speciiic detail for the purpose of disclosure will suggest various modifications and substitutions under our concept, and we reserve the right to all such departures that properly come within the scope of our appender1 claims.

We claim as our invention:

1. A well-drilling deviation detector for service in a drilling uid stream in a drill pipe, said detector including: a housing adapted for insertion into said drill pipe, said housing having a portion forming a channel for said uid stream; a mechanism movably mounted in said housing for reciprocation, said mechanism being movable in one of its directions of reciprocation in response to said iiuid stream, said mechanism having a portion cooperative with said channel portion of the housing to vary the effective cross section of the channel at successive stages in the movement of the mechanism, thereby to produce successive pressure variations in the fluid stream for detection at the surface of the well; and gravity-responsive means to limit the reciprocative movement of said mechanism at various points according to the degree of deviation of the housing from vertical, thereby to vary the number of successive pressure variations to reveal said degree of deviation.

2. A well-drilling deviation detector for service 1n a drilling uid stream in a drill pipe, said detector including: an instrument case adapted for insertion into said drill pipe, said \case being substantially smaller in cross-sectional area than the interior of said drill pipe to permit said stream to now past the case; means connected with said case to form a channel for the drilling uid streambeyond one end ofthe case; a mechanism movably mounted in said case for reciprocation, said mechanism being movable in one of its directions of reciprocation in response to said uid stream, said mechanism having a portion cooperative with said channel-forming means to vary the eective cross section of the channel at successive stages in the movement of the mechanism, thereby to produce successive pressure variations in the uid stream for detection at the surface of the well; and gravity-responsive means 'to limit the reciprocative movement of said mechanism at various points according to the degree of deviation of the case from vertical, thereby to vary the number of -successive pressure variations to reveal said degree of deviation.

3. A well-drilling deviation detector for service in a drilling iiuid stream in a drill pipe, said detector including: an instrument case enclosing instrument :duid and adapted for insertion into said drill pipe, said case being smaller in cross-sectional area than the interior of said drill pipe to permit said stream to flow past the case; means carried by said case for contact with the surrounding drill pipe to align the case inthe same longitudinal direction as the drill pipe; a reciprocative plunger member extending through one end of said case; spring means to move said plunger member in a rst reciprocative direction, said plunger member being movable in the opposite or second reciprocative direction in response to said drilling stream, said case having a movable wall to permit displacement of said instrument uid in response to movement of said plunger member, whereby the combined volume of the case and of the exposed portion of the plunger member isl constant during plunger reciprocation; a passage member carried by said case for cooperation with said plunger member to temporarily restrict the iiow of said stream at successive spaced points in the movement of the plunger member in said second direction, thereby to produce successive pressure rises in said stream at the surface of the well corresponding in number to the extent of Vmovement of the plunger; and a gravity-responsive means to limit the reciprocative movement of said plunger member in said iirst direction at various points according to the degree of deviation of said container from vertical, whereby the number of successive pressure rises reveals said degree of deviation at the surface of the well.

4. A combination as set forth in claim 3 in which one of the two recited cooperating members moves longitudinally past the other and in Y which one of said members is alternately expanded and contracted 'in prole to produce said successive restrictions of said stream.

5. A well-drilling deviation detector for service in a drilling uidstream in a drill pipe, said detector including: a case enclosing instrument iluid and adapted for insertion into said drill pipe, said case being smaller in cross-sectional area than the interior of said drill pipe to permit said stream to flow past the case; a reciprocative plunger member extending through one end of saidcase; spring means to move said plunger member in a iirst reciprocative direction, said plunger member being movable in the opposite or second reciprocative direction in response to said drilling stream, said case having a movable wall to permit displacement of said instrument fluid in response to movement of said plunger member, whereby the combined volume of the case and of the exposed portion of the plunger member is constant during plunger reciprocation; means forming a channel in said case for displacement flow of said instrument fluid,- said channel-orming means including a sharp-edged oriiice to minimize variation in the rate of displacement ilow of the instrument fluid attributable to variation of viscosity of the instrument iluid; a passage member carried by said case for cooperation with said plunger member to temporarily restrict the ow of said stream at successive spaced points in the movement of the plunger member in said second direction, thereby to produce successive pressure rises in said stream at the surface of the well corresponding in number to the extent of movement of the plunger; and a gravity-responsive deviation detector to limit the reciprocative movement of said plunger member in said rst direction at various points according to the degree of deviation of said case from vertical, thereby to vary the number of successive pressure rises to reveal Y said degree of deviation at the surface of the 6. A Well-drilling deviation detector for service tector including: a case enc1osing instrument fluid and adapted for insertion into said drill pipe, said case being smaller in diameter than the interior of the drill pipe to permit said stream to flow past the case; a reciprocative plunger extending through one end of said case, said plunger being eiective to temporarily restrict the flow of said stream at successive spaced points in the movement of the plunger in one direction, thereby to produce successive pressure rises in said stream at the surface of the well corresponding in number to the extent of movement of the plunger; a piston in said case connected with said plunger to move therewith, there being a passage for iiow of said instrument uid from one side of the piston to the other, there being a sharp-edged restriction in said passage; yielding means to move said plunger and piston in a rst reciprocating direction, said plunger and piston being movable in the opposite or second reciprocating direction in response to said stream of drilling iiuid; and a gravity-responsive deviation detector to limit the reciprocative movement of said plunger and piston in said cluding a chamber having a flexible wall, said chamber being in communication with said cylinder and enclosing a portion of said instrument fluid, said portion varying in volume with movement of said plunger.

8. A signaling clinograph for service in a well, the well having a channel for a stream of drilling fluid, said clinography including: a mechanism for subterranean operation in saidwell, said mechanism being movable in opposite directions and being adapted to move in one of the opposite directions in response to said uid stream; means cboperative with said mechanism to s end a series of signals to the surface oi the well when said mechanism moves; a gravity-responsive deviation-detector to limit the movement of said mechanism in accord with the degree of the deviation of the well from vertical, thereby to vary the number of signals in said series to indicate such deviation at the surface of the well; a ilrst bearing member to support said gravity-responsive deviation detector for oscillation; and a second bearing member unitary with the gravity-responsive deviation-detector, one of said bearing members being formed with a seat and the other of said bearing members being formed with a pointed projection extending into said seat.

9. A Well-drilling deviation detector for service in a drilling ud stream in a drill pipe, said detector including: a housing adapted for insertion into said drill pipe; a mechanism in said housing, said mechanism being movable in opposite directions and being adapted to move in one of the opposite directions in response to said uid stream, said mechanism having a normal position at one limit of its range of movement; a pendulum in said housing positioned in the path of movement of said mechanism to be held immobile by said mechanism at said normal position of the mechanism; a rst bearing means unitary with said pendulum; a second bearing means carried by said mechanism for cooperation with said first bearing means to pivotally support the pendulum, said two bearing means being positioned for separation at said normal position of the mechanism and for mutual cooperative contact upon movement of the mechanism away from said normal position; signal means responive to movement of said mechanism in one direction; and means cooperative with said pendulum to limit the movement of said mechanism and thereby limit operation of said signal means in accord with deviation of said housing from vertical.

10. In a deviation detector for service in a well bore, the combination of: an indicating mechanism for reciprocative operation in said bore; a gravity-responsive deviation detector to limit the movement of said indicating mechanism at selected positions in accord with deviation of the well bore; and dash-pot means for retarding movement of said indicating means to permit stabilization of said deviation detector prior to limiting action by the deviation detector, said dash-pot means including a body of liquid and a sharp-edged orice to minimize variation in rates of dash-pot flow caused by variations in viscosity of the uid.

l1. A signaling deviation detector for service in a well having a channel for a stream of drilling fluid, said deviation detector including: a

' mechanism movable in opposite directions; a

otal manner when the pendulum is at its relative extended position, the cooperating surfaces ot said bearing means being separated when the pendulum is at its relative retracted position: means to urge said mechanism in one of its directions whenever iiow of said drilling fluid substantially ceases; means cooperative with the pendulum to limit the movement of said mechanism in said one direction in accord with deviation of the well bore from vertical; signal means responsive to movement of said mechanism in said direction to indicate the magnitude of such movement, thereby to indicate the magnitude of deviation from vertical; means actuated by dynamic pressure from the owing drilling uid to move said mechanism in its opposite direction, thereby moving said pendulum longitudinally in said opposite direction; and stop means in the path of said pendulum to cause said movement in the opposite direction to result initially in retraction of the pendulum and subsequently in fluid-derived pressure on the part of said pendulum longitudinally thereof to hold the pendulum normally immobilized during drilling operations.

l2. A signaling deviation detector for service in a Well having a channel for a stream of drilling uid, said deviation detector including: a mechanism movable in opposite directions; a pendulum movable longitudinally relative to said mechanism between a retracted position and an extended position; bearing means to support the pendulum from said mechanism in a freely pivotal manner when the pendulum is at its relative extended position, the cooperating surfaces of said bearing means being separated when the pendulum is at its relative retracted position; means to urge said mechanism in one of its directions whenever flov of said drilling iiuid substantially ceases; means cooperative with the pendulum to limit the movement of said mechanism in said one direction in accord with deviation of the Well bore from vertical; signal means responsive to movement of said mechanism in said direction to indicate the magnitude of such movement, thereby to indicate the magnitude of deviation from vertical; means actuated by dynamic pressure from the flowing drilling fluid to move said mechanism in its opposite direction, thereby moving said pendulum longitudinally in said opposite direction; stop means in the path of said pendulum to cause said movement in the opposite direction to result initially in retraction of the pendulum and subsequently in iluidderived pressure on the part of said pendulum longitudinally thereof to hold the pendulum normally immobilized during drilling operations; and retaining walls positioned to surround said pendulum at its normal position to prevent lateral movement of the pendulum as additional means to immobilize the pendulum.

FRED M. VARNEY.

JUSTIN ARNOLD VARNEY.

CERTIFICATE oF CORRECTION.

Patent No.'2,529,752. september 21, 19M.

Letters Patent should be lreadY with this correction therein that the seme Henry Van Arsdale', (Seal) Acting' lComznissionefz' of Patents.

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