US2166212A - Apparatus for measuring well depths and well strings - Google Patents

Description

July 18, 1939. J. T. HAYWARD 2,166,212

APPARATUS FOR MEASURING WELL DEPTHS AND WELL STRINGS 4 Sheets-Sheet 1 Filed Dec. 27, 1937 3 9 .QIIIII 2 H w m ..I W" A 7 I I I I l 6 FIG. I

INVENTOR JOHN T. HAYWARD ATTORNEY y 1939- J. T. HAYWARD 2,166,212

APPARATUS FOR MEASURING WELL DEPTHS AND WELL STRINGS Filed Dec. 27, 1937 4 Sheets-Sheet 2 INVENTOR JOHN T. HAYWARD avz ATTORNEY July 18, 1939. .1. T. HAYWARD 2,156,212

APPARATUS FOR MEASURING WELL DEPTKS AND WELL STRINGS Filed Dec. 27, 19:57 4 Sheets-Sheet s INVENTOR JOHN T. HAYWARD evw AT TORN EY July l8, 1939. J. T. HAYWARD 2,166,212

APFARATUS FOR MEASURING WELL DEPTHS AND WELL STRINGS Filed Dec. 27, 1937 4 Sheets-Sheet 4 FIG. 9 4 INVENTOR lOHN T. HAYWARD ATTORNEY Patented July 18, 1939,

UNITED STATES PATENT OFFICE APPARATUS FOR DIEASUBING WELL DEPTHS AND WELL STRINGS This invention relates to well depth measurement and particularly to apparatus for measuring the depths of wells and the lengths of well strings by measurement of the linear movements of a drilling or other well string inserted in the well bore.

In the drilling of wells, particularly oil wells. exact knowledge of the depth of the well at all stages of the drilling operation is extremely important. This is particularly true in the case of wells being drilled by the rotary method, wherein the sub-surface position of the oil producing formation being sought is calculated beforehand, ordinarily, by correlation with he same or other formations in adjacent wells, or

is determined by geologic or geophysical measurements. As the drilling fluids conventionally used in the drilling operation tend to obscure the evidence of oil when the producing formation is penetrated by the drill, it is'highly important that the depth of the well and the position of the drill be known at all times in order that the approach of the drill to the desired formation may be carefully regulated and controlled.

Otherwise, the drill may pass entirely through the desired formation and cause a complete loss of the well, or at best, will .result in additional expense of "plugging-back and of special "cleanout" operations and the like.

fhe extreme imporance of exact measurements is graphically illustrated in the case of certain wells drilled in the Gulf Coast region of Texas and Louisiana, where the oil producing formation is only six feet thick and lies at a depth of over'ten thousand feet below the surface of the ground. In other words, an error of only six one-hundredths of one percent in the measurement of the total depth of such a well could cause the driller to miss theproducing formation 40 altogether. The .failure of such a well will resuit in tremendous financial loss as the 'cost of drilling wells of such great depth ordinarily is considerably more than $100,000.00.

At the present time, well depths are measured by measuring the length of the drill pipe as the drilling proceeds. This is done by measuring with a steel tape each section of drill pipe as it is added to thedrilling string, the cumulative length being taken as the maximum depth of 60 the well. As each section is measured before being added to the string, the stretch" produced in the sections by the great weight of the drill pipe itself and of the drilling tools attached thereto, cannot be measured exactly and is ordinarily calculated and allowed for on the basis of previously determined tensile characteristics of the drill pipe. Such a more or less empirical calculation may result in an error in measurement of the total length of the drilling string,

' which will be sufilcient, in wells of great depth 5 such as those noted above. to cause the driller to miss the producing formation entirely. Other sources of error in this method of measurement arise through the fact that the drilling is never continuous and uninterrupted. The drill bit 10 must be repaired or replaced frequently, which operations require the complete withdrawal of the entire drilling string for each repair or replacement operation. As the drilling string must be removed in sections, very often, many of the sections must be discarded lue to defects, and must be replaced by others. the measurements of which are different from those removed because of the lack of exact uniformity of length of standard drill pipe sections. Each section re- 20 moved and each new section added, therefore, must be individually measured and the full'length of the new string recalculated and corrected for any changes so made, and when it is considered that in the drilling of a very deep well, the en- 25 tire 'drllling' string maylbe removed from the well and re-introduced from fifty to one hundred times before. final completion of the well. the factor of human error, particularly, becomes increasingly great and may oftentimes be disastrous to the success of the drilling operation.

Another method of measurement is that wherein a weighted line is lowered into the well until the weight on the end of the line strikes the bottom of the well and the line measured 35 by meansof a calibrated measuring wheel as it descends or is pulled from the well. This method has several disadvantages. One is that the drilling operation must be stopped completely every time the measuring line is run.- Also, as the 40 I weight must ordinarily descend through a column of relatively viscous drilling mud, difilculty is often experienced in running the line. Again. the weight may lodge against an obstruction in the drill pipe or well bore and produce an 4 erroneous result. Stretch of the very long measuring line when the well depth is great is an additional factor which complicates, and often adversely affects, the accuracy of this method of measurement.

well string and only when the string is suspended in the well here and in motion linearly therein.

Briefly this method of measurement is accomplished by attaching a measuring line to the conventional traveling block from which the drilling or casing strings are normally suspended as they are run in and out of the well, and measuring the linear movements of the measuring line, by means of a conventional calibrated measuring wheel. as the line follows the upward and downward movements of the block between the crown and floor of the derrick in raising or lowering the' well string. For recording the movements of the measuring line, an automatic duplex-type counter is providedin cooperation with the measuring wheel. One portion of the counter adds together the measurements of only the progressive downward movements of the measuring line, when the string is supported by the block, and visibly records, non-reversibly, the total of these measurements, this total giving the maximum depth of the well, irrespective of subsequent or intermediate upward movements of the well string. The other portion of the counter adds algebraically the measurements of all the upward and downward movements of the measuring line when the block supports the well string and visibly records this total. The algebraic sum thus obtained, gives the length of the string remaining in the well after any number of reciprocating movements of the string. A means is provided to disconnect the counter from the measuring wheel when the string is not in movement linearly in the well. This method and means of measurement automatically provides the driller with continuous and exact information as to the maximum depth of the well, and the position, i. e., the length,ofthestringinthe well at any time, all as willbe more fully described hereinafter.

Therefore, it is a principal object of this inventionto provide apparatus for measuring well depths. by measuring the linear movements of a well string in a well.

Another: obiect is the provision of apparatus for automatically measuring well depths while the well isbeing drilled.

.Lfurther object is the provision of apparatus for measurement of drilling strings, whereby linear: measurements of the progressive downward movements of the drilling string are selectively" and: non-reversibly added together to thereby obtainzthe maximum depth of the well. and lnadditiom the algebraic sum of the measurements ot allot the linear movements of said string imthe-well is continuously obtained to thereby'measure the-length of the string in the welll at any particular period in the drilling operation;

Amadditlonabobiectisthe provision of apparatusc: suitablefor successfully practicing the method :9; thkinvention.

Otherandzmore-specifln objects will become apparent fronsthe following detailed description- Fig: 3 is a view similar to Fig. 2 showing the relationship of parts of the apparatus when the drilling string is supported directly on the rotary table.

Fig. 4 is a cross-sectional view of the measuring wheel according to this invention as taken along line 4-4 of Fig. 2.

Fig. 5 is a longitudinal sectional view of the mes-curing wheel taken along l ne 5-5 of Fig. 4.

Fig. 6 is a detail of electri'al connections included in certain of the apparatus in accordance with this invention.

Fi s. 7. 8 and 9 are details of various modifications of apparatus in accordance with this invention.

Referring to Fig. I, particularly. it will be seen that a conventional rotary drilling rig is herein illustrated. The principal parts shown consist of a derrick I, mounted on a floor 2, a crown block pulley 2 from which a conventional traveling block is suspended by means of the ordinary wire cables I terminating in the hoisting or drilling line 6, movement of which about crown pulley 3 controls the raising and lowering of traveling block 4. Mounted on derrick floor 2 is the usual rotary table I through which the usual drilling string indicated at l extends into the well bore I. Drilling string 2 consists of a rotary drive member or kelly i0 attached by a swivel Ii to a hook l2 suspended fromtraveling block 4, hollow drill pipe I! connected by a coupling ll to the kelly. and a drill bit ll attached to the lower end of the drill pipe.

Some-of the principal parts of rotarytable I are shown in somewhat greater detail in Figs. 2 and 3. As illustrated. the table comprises a rotary cylinder ll about the upper edge of which is mounted a bevel gear I], which is adapted to be rotatively driven in the conventional manner by a geared shaft, not shown. Cylinder It is rotatably mounted on roller bearings i. which roll in a race II, and the entire assembly is supportedonabasemember 22 whichis in turn spacedlysupported from derrick floor 2 by beams 2|. A hollow master bushing 22 is supported within cylinder I on shoulders 22 and-the upper section of the interior of bushing 22 is cut away to form a square seat 2 adapted to receive a square rotary bushing 2| which slidably receives kelly II. A section of the interior of master bushing 22 below seat 24 is provided with a downwardly tapering conical surface. generally termed a slip-bowl 20, adapted to receive toothed slips 21 (Fig. 3) into wedging engagement with the drill pipe ii for purposes to be more fully described hereinafter.

A measuring device for measuring the vertical movements of traveling block 4 consists of a measuring line 22, which is attached to traveling .block 4 and is led vertically therefrom to a point that one turn of measuring line 22 thereon will be equivalent toone foot of the line, or in other words. one turn of line 28 about drum 22 will represent one linear foot of vertical movement of traveling block 4. Of course, the dimensions of the drum 32 may be varied for calibration to other lengths of the measuring line. Drum 32 is rigidly mounted on a shaft 33 by means of a key 34 and shaft 33 is Journalled on a supporting frame 33 which is fixedly attached to any suitable support, such as a leg of derrick l, as shown in Fig. l. A portion of the drum about shaft 33 is hollowed out to form an annular space 33 in which is mounted a coil spring 31 surrounding shaft 33. One end of spring 31 is fixedly attached to shaft 33 and the other to frame 33. Spring 31 cooperates with drum 32 and frame 33 to hold tension on measuring line 23 at all times. Measuring line 23 is of at least suiilcient length to follow block 4 from its highest position in the derrick to its lowest position therein, and the peripheral surface of drum 32 is of sufficient area to properly accommodate this length of line.

Fixedly mounted on one end of shaft 33 is clutch member 33 which is adapted to engage a cooperating clutch member 33 which is mounted on a shaft 43 of a registering counter 4|. Shaft 43 is slidably supported in a bearing 42 and a coil expansion spring 43 surrounds shaft 43, and has one end attached to bearing 42 and theother to clutch member 33, and is adapted to hold clutch member 33 normally in engagement with clutch member 33.

A spline connection 44 (Fig. 3) is provided for slidably connecting shaft 43 to counter 4| in order that shaft 43 will be in driving engagement with counter 4|, at all times, while permitting axial movement ofthe shaft. A solenoid 43 surrounds a portion of the shaft 43 between bearing 42 and counter 4|; and an iron core 43a is fixedly attached to this portion of shaft 43 so that when current is applied to the solenoid, it acts to draw core 43a in the right hand direction and thereby cause shaft 43 to move in the direction of counter 4| against the resistance of spring 43 and to pull clutch member 33 out of engagement with clutch member 33, thus disengaging counter 4| from measuring wheel 3|. Suitable current leads 43 and 41 are connected to solenoid 43, lead 43 leading to a ground connection while lead," leads to one terminal of a suitable current source. such as a battery 43.

Electrical connections are provided in rotary table I for completing a circuit including solenoid 43 and battery 43. Referring to Figs. 2, 3 and 6 particularly, the form of connections shown include a contact pin 43, which is reciprocably mounted in an opening 33 in the wall of slip bowl 23 and is provided with a rounded end normally adaptedto protrude into the bowl. The opposite end of contact pin 43 forms an electrical contact point 43a and is fixedly attached to one end of a resilient member suchas a leaf spring 3|, which is an electrical conductor having its other end I fixed to the inner side of the wall of the slip bowl.

and in conducting contact therewith. Spring 3| cooperates withpin 43 and the wall of slip bowl 23 to normally cause pin 43 to protrude into the bowl. A contact switch arm 32 is mounted within master bushing 22 and is positioned in registration with pin 43, so that when pin 43 is depressed or pushed inwardly from the interior of slip bowl 23, and assumes the position shown in dotted out,- line in Fig. 6, contact point 43a will make contact with switch arm 32. Switch arm 32 is attached to a slip ring 33 mounted in the lower face of master bushing 22. Blip ring 33 is made of a suitable electrical conductor metal and is suitably insulated from the metal body of master bushing 22 by insulation 34. Mounted in base member 23 and insulated therefrom by insulation 33a, is a brush 33, which is in registration with slip ring 33, and is held in continuous electrical contact therewith by means of a spring 53, which makes electrical contact with brush 35 and is connected by a lead 31 to the other terminal of battery 43. A lead 33 connects a portion of the rotary table. such as race I3, to ground, although the provision of such a lead to ground is ordinarily unnecessary since the rotary table is generally thoroughly grounded through direct metal-tometal contact with the metal structure of the derrick.

When contact pin 43 is pressed ltno contact with switch arm 32, in a manner to be more fully described hereinafter, the circuit, which includes the several parts of the rotary table, and the solenoid 43, will be closed, and current from battery 43 will flow to the solenoid and actuate core 45a to effect the above described movements of shaft 43.

Counter 4| comprises generally a duplex-type counter having two sets of counting wheels. For purposes of clarity, one of these will be designated a progressive counter and is indicated generally by the numeral 33, and the other, an algebraic counter, designated by the numeral 3|.

The construction of the counters is more or less conventional. 'Algebraic counter 3| is an ordinary revolution counter which is directly connected to shaft 43 and adds all the revolutions of the shaft in one direction and subtracts when reversed, thus always recording the algebraic sum of all the revolutions of the shaft. Progressive counter 33 is a maximum revolution counter, and is also connected to shaft 43, but is adapted to count revolutions of the shaft rotating in one direction only. When the rotation of shaft 43 is reversed, the reading on counter 33 will remain unchanged. and counter 33 will not be actuated again to register additional revolutions until the reading of counter 3| has returned to that appearing on counter 33. Thus counter 33 will count only those revolutions of shaft 43 which are progressively in one direction only, while counter 3| will count all the revolutions of the shaft in either direction of rotation and will al- :vays record the algebraic sum of these revoluions. The apparatus above described is utilized for the measurement of well depth and the length of the well string in the following manner:

Referring to Figs. 1 and 2 in particular, which show the more or less conventional arrangement of a rotary drilling string suspended from traveling block 4 and extending through rotary table 1 into the well 3 being drilled, the measuring operations will be described in connection with the measurement of the movement of a single section of drill pipe during the drilling operation, and it will be readily understood that the method of measurement described will be equally applicable to the movements of the drill pipe throughout the entire drilling operation.

In conventional rotary drilling. the drilling op- ,eration will be conducted more or less continuously until a depth of well equal ,to the length of a section of drill pipe i3 will have been drilled. whereupon the entire drilling string will be drawn upwardly from the bottom of the well by drawing traveling block 4 upwardly through the medium of drilling line 3, until the end of the drill pipe section nextbelow kelly I3 is above rotary table I. Rotary bushing 23 will be removed from master bushing 22 and will be replaced by slips 2! (Fig. 3) which will support the well string while the lrelly is unscrewed therefrom. A new section of drill pipe is then connected to the upper end of the drill pipe in the well. The slips are then removed, and the weight and support of the entire drilling string again transferred to traveling block 4 which will lower the string until the bit is again near the bottom of the, well. The kelly will now be connected again to the upper end of the drilling string, whereupon drilling will be resumed for another interval of depth equal to the length of the kelly.

For the purposes of this description, it will be assumed that the drill bit is resting on the bottom of the well, and that a new section of drill pipe has been added to the drilling string, thereby again placing traveling block 4 at about its highest normal position in the derrick, and that drilling is about to be resumed. At this point, progressive counter will register a measurement which is that of the depth of the well as measured from the bottom of the well to the point Just above the rotary table. conventionally considered as the top of the well, and known as the measuring point". All measurements are made relative to this point. Since the drill bit is resting on the bottom. the length of the drilling string from the bottom of the well to the measuring point will be equal to the depth of the well and therefore equal totals will be registered on both the algebraic counter GI and progressive counter 60.

The rotary drilling motion of the drilling string is begun and drilling continued until a distance has been drilled which is substantially equal to the full length of the kelly, and at this point, the upper mi of kelly i0 and traveling block 4 will be at about the position illustrated in Fig. 2. As traveling block 4 descends from its high position to its lower position above the rotary table in following the downward movement of the drilling string, both counters will register the length of the downward travel of the block through the medium of measuring line 28 and measuring pulley 3i. As the downward distance moved by the block is now in addition to the sum of the preceding downward movements, the new measurement recorded on progressive counter 60 will be the new depth of the well and likewise. the new figure appearing on algebraic counter 8! will represent the new length of drilling string in the well, and both measurements will still be equal.

To continue drilling, it is now necessary to add still another section of drill pipe. To do this, the rotary table is stopped, rotary bushing 25 removed from the table, and the entire drilling string pulled upwardly from the well by block 4 through pulling force applied to drilling line Ii. until the upper end of the drill pipe section next below the kelly appears above the rotary table in about the position shown in Fig. 3. The upward movement of the traveling block in effecting this withdrawing operation will be measured by measuring wheel 3| which will rotate, however, in the reverse direction, as measuring line 28 is automatically reeled thereon through the action of spring 31. The reverse rotation of measuring wheel 3| will reverse algebraic counter BI and the reverse measurement so obtained will be subtracted from, i. e. algebraically added to, the measurement previously appearing on counter BI and the final figure will represent the oris nal length or the drilling string minus the length withdrawn from the well, and will thus represent the length or the drilling string remaining in the well. Since progressive counter 40 is unafiected by reverse rotations oi measuring wheel II, the measurement recorded thereon will remain unchanged and will continue to show the full depth of the well. Therefore. at the completion or the described withdrawal operation, counter 4| will register two iigures, one the depth of the well and the other the length oi the drilling string remaining in the well. Of course, algebraic counter I will continuously and automatically register the changing length of the drilling string in the well as the string is drawn upwardly in the derrick, and the drill operator will be supplied with continuous information as to the depth 01' the well and the amount of drill pipe in the well at any instant during the upward or downward movement of the drilling string.

As noted. the drilling string has now been drawn upwardly from the bottom oi well to the position shown in Fig. 3 preparatory to addition oi another section of drill pipe, and rotary bushing 25 has been removed. Slips 21 are now dropped into place in slip bowl 2! to supportingly engage .the drill pipe, and the entrance of the slips into the slip bowl will act to push contact pin 48 and its electrical contact point 49a against switch arm 62 and thereby close the circuit which includes the rotary table and solenoid 46. Closing of this circuit will cause current to flow from battery 48 to the solenoid which will be energized thereby to cause disengagement of clutch members 38 and I! and thus disconnect the counters from the measuring wheel. No movements of traveling block 4 can now ailfe'ct the counters, and the traveling block may be utilized in the conventional manner to assist in disconnecting the kelly from the drilling string, drawing into the derrick a new section of drill pipe, swinging the newly connected section into position over the end of the drill pipe protruding above the rotary table. and in connecting the new pipe section and the kelly into the drilling string.-

The new pipe section is now made up into the drilling string and the traveling block, which is now attached directly to the upper end thereof. is moved upwardly very slightly to take the full weight of the drilling string and permit the removal oi the slips preparatoryv to lowering the drilling string back into the well. The removal 01' the slips will permit the return of contact pin 49 to its normal position and thus break the solenoid circuit, causing the counters to be reconnected to the measuring wheel. The kelly is again connected into the drilling string which is now lowered into the well by the traveling block until the bit is again on bottom, and this downward movement will be registered on algebraic counter 4i. Since at this point, the drilling string will move downwardly exactly the same distance it was previously raised, the measurement of the length of the drilling string which will now appear on algebraic counter 8| will be the same as that previously registered, and will be equal to the depth of the well as recorded on progressive counter 80, which, of course, will remain unattected, since it does not change until after the figures on the algebraic counter are the same as those on the progressive counter.

Drilling is again resumed and both counters begin again to register the descending movement of the traveling block as the drill moves deeper into the'earth, and when the downward movesteam both counters will record the new w'ell depth and the new length of the drilling string below the measuring point. Drilling is again halted and the previously described operations foradding a new drill pipe section repeated and the movements of the traveling block which are significant with respect to well depth and drilling string measurements, recorded as described.

By conducting the measuring operations as above described, from the beginning of the drilling operation and continuing them through the entire drilling operation, progressive counter ill will continuously record, non-reversibly, only the progressive downward movements of the drilling string, while algebraic counter 6| will record the algebraic sum of all the upward and downward movements of the drilling string and the counters will thus provide, automatically, a continuous record of the well depth and of the length of the drilling string remaining in the well at every stage of the drilling operation.

It will be evident from the foregoing description, that the method of the invention comprises the measurement of well depths and of well strings by measuring the linear displacement of a well string support, moving in a zone extending vertically above the well, and selectively measuring those movements of the support when a well string is movably supported thereby in the well. The invention additionally contemplates the steps of adding together cumulatively the measurements of only the downward movements of the support when the well string is movably supported thereby in the well, and adding together algebraically all of the upward and downward movement of the support when the well string is movably supported thereby in the well.

By this method of measurement, the several errors arising in former measuring methods are eliminated. For example, the factor of "stretch of the drilling string is automatically compensated for and included in the measurements recorded,

for, in order to actuate the counters after each addition of a pipe section, the traveling block must lift the entire drilling string upwardly in order to free the slips and thereby break the circult to the solenoid. As the weight of the drilling string is taken on the traveling block, the new section of pipe will begin to stretch in accordance with the weight of the string suspended therefrom, and this will require the traveling block to be moved upward a distance equal to the maximum extent of the resulting stretch before the slips, can be fully released. Therefore, at the instant the slips are fully released and the counters actuated, the traveling block will be spaced section, plus'the amount of the stretch. Then as the traveling block descends with the subsequent downward movement of the drilling string, the counters will record a downward movement of the block which will be equal to the stretched length of the new pipe section, and thus the-measurements recorded on both counters will be in terms of the full length of the drilling string.

By the method and apparatus of this invention, every vertical movement of the traveling block when it supports the well string in the well is automatically measuredand recorded, and since, normally, the drillingstring cannot be moved vertically in the well except when it is movably supported by the traveling block or similar movable support member, it will be evident that no vertical movement of the drilling string which is of significance in the measurement of the well depth or of the length of the string in the well, can escape the measuring and recording apparatus. and the factor of human error is thus largely eliminated. It will also be evident that the measurements may be, and are, made while the drilling operation is in progress, for the rotary movement of the illlng string does not effect the measurin ap tus in any way and since every increment oi downward or upward movement of the drilling string is reflected in an equal movement of the traveling block, every increment of downward or upward movement of the drilling string will be automatically measured and recorded by the counters.

Furthermore, since only the vertical movements of the traveling block are measured and since these movements are limited in length by the vertical distance between the crown and floor of the derrick, only a relatively short measuring line is required, and since the measuring line is not required to support any substantial weight, errors due to stretch of the measuring line are eliminated for all practical purposes.

In the foregoing description, this invention has been applied to the measurements of well depths and well strings during a conventional rotary drilling operation. However, it will be evident that the invention may be applied equally advantageously to the measurement of casing or tubing strings as they are run into and out of a well in the usual manner. a

Frequently casing or tubing strings are run into the well through the. rotary .able and the slips and slip bowl previously described will be utilized, as described, to hold the string while new sections are added to or removed from the string and the measurements of the strings will be obtained in exactly the same manner as in-the case 0! drilling strings. At other times, the master bushing 22 may be removed from the rotary table and the slips and slip bowl therein will be replaced by a conventional tubing or casing spider 62, which is mounted on the rotary table in the manner illustrated in Fig. 7. The measuring operations are conducted in exactly the same way as previously described though the electrical connections are changed slightly by mounting the switch, consisting of contact pin it and switch arlm. 52, on spider 62 rather than'in the rotary ta le.

Fig. 8 shows another modification of apparatus for disconnecting the counters from the measuring wheel when there is no vertical movement of the well string'in the well. In this modification, the counters are dis-connected from the measuring wheel when the weight of the well string is brought to bear on the rotary table, as when the slips 21 support the well string while the traveling block may be engaged in other operations. The same electrical circuit and the ,same general form of switch are employed as described above in the principal modiflcation,,but the position of the switch is changed by placing contact pin 48 in one of the beams 2| and allowing it to protrude slightly above the upper surface oi the beam. The rotary table is spaced slightly above beams 2| and normally out of contact with pin 4! and is supported in this position by means of springs 83, which are adapted to be compressed when a load greaterthan the normal weight of the rotary table is applied thereto. Thus, when the weight of the well string is brought to bear on the rotary table, and normally such circumstancewilloccuronlywhentherswillbenoim- 'mediate further vertical movements at the well stringin thewell,therotarytablewillbedepressed against springs II and base member is will depress contact pin ll into contact with switch arm l2, thereby closing the solenoid circuit and dis-connecting the counters irom the measuring wheel. Upon the lifting of the weight 01 the well string from the rotary table, which action must necessarily occur before the well string can be moved vertically in the wel the springs it will liit the rotary table from beams 2i and allow the contact pin to return to its normal position, thereby breaking the solenoid circuit and permitting reconnection oi the counters to the measuring wheel.

In still another modification, the conventional weight indicator device. which are actuated by the pull applied to drilling line I by the weight oi the well string suspended therefrom, may be employed to connect or disconnect the counters irom the measuring wheel. In this case. when the weight oi the well string is taken on the slips in the rotary table, the pull on the drilling line will be reduced sharply, and the resulting movement of the weight indicator mechanism will be applied to efiect disconnection of the counters. Immediately upon reapplication of the weight of the well string to the drilling line, when the string is lifted from the slips. the opposite movements of the weight indicator. corresponding to the increase in the pull on the drilling line, will be utilized to re-connect the counters to the measuring wheel.

Straight mechanical devices, such as hydraulic tubes and plungers may be used in place 0! the electrical circuit and magnetic clutch heretofore described, for actuating the axial movements of shaft 40 in disconnecting the counters from the measuring devices.

The connection irom mmsin'ing wheel ii to counter 4i may be modified in various ways. One modified arrangement is shown in Fig. 9, which illustrates an arrangement wherein a' sell-synchronoustransmission system, commonly known as a "sol-syn" system. is substituted for the direct,

mechanical connection. such as shaft-l3, irom measuring wheel II to clutch member 3!. thisv arrangement. pulley 2!. overwhich measuring line It isrun.is calibrated to serve'in place or measuring wheel 8! for messurlng'the movements or the line. and the armature or one Belsyn mototllis connected directly to the shaft or pulley" 2st; The armature oi the other Bel-syn motorliisconnecteddirectlytoshattil. By this arrangement. every revolution of pulley I! wilLbetransmitted electrically through leads Ila to. chair It, justaathouglnshait II were connecteddirectlrtopulley- II, in accordance with the-welllknowmflmctio'na ot a Bel-syn system. Also. in.thia arrangement, a weight member a is attachemtotheireeendotthemeasuring line and-.substitutedior the spring reel action or measuringcwheei ll ioeholding tension continu- M ously on measuring line ll.

. varyingtheswitchdetailsslightlysothatwhenit isdesiredto measure movements or the well string,thecirc1ntthroughtheBel-l!nmotorswill beclosedwhenthewellstringismovingvertically invention may be applied in connection with operations other than well drilling operations and particularly to those wherein the linear distance to which a linearly moving elongated member extends beyond a fixed point cannot ordinarily be measured directly with suitable accuracy.

when applied generally, the method of this invention may be said to comprise, indirectly measuring the lineardistance to which one end 0! a linearly moving elongated member extends beyond a fixed point by measuring directly the linear movements 0! the opposite end oi the member on the opposite side of said fixed point.

Numerous modifications and alterations may be made in the size. tom and arrangement 01 the details oi apparatus in accordance with this invention without departing from the scope of the invention as defined in the appended claims. What I claim and desire to secure by Letters Patent is: y

1. In apparatus for registering movements of objects relative to a well. a relatively fixed support member adjacent a well and having an opening therein registering with the well, a register for registering movements 0! objects relative to said well, an electro-magnetically releasable clutch member normally placing said register in movement-registering connection with said objects, a normally open electrical circuit connecting said clutch member :with said support member. and circuit-cloeing-means positioned in said support member to close said circuit to thereby release said clutch member. said circuit-closing means comprising a normally open switch member positioned adjacent said opening and adapted to be closedby a compressive force laterally applied irom within said opening. and means removably insertable in said opening ior applying lateral compression therein for closing said switch member. I

2. In an apparatus for registering movements '0! obiects relative to a well, a rotary table adjacent the'top oi said well, a'register ior registerlog movements or objects relative to said well. an

electromsgnetically releasable clutch member normally placing said register in movementregistering connection with said objects. a slip bowl in said rotary table, slips insertable in said slip bowl. an electric circuit connecting said clutch member with said slip bowl, and normally open switch means in said circuit positioned in said slip'bowhsaidswitch means being adaptedto be closed upon the insertion oi said slips insaid slip bowl to thereby close said circuit and release said clutch member.

8. In apparatus (or registering movements of objects relative to a well. a rotary table adjacent the top 0;! said well, a register ior registering movements 01 objects relative to said well. an electro-magnetically releasable clutch member normally piecing said register in movementregistering connection with' said objects, a slip bowl in said rotary taole, slips insertable in said slip bowl. an electric circuit connecting said clutch member with said slip bowl. and normally open switch means in said circuit positioned in said slip bowl. said switch means being adapted tobe' closed uponinsertion oi said slips in said slip bowl to thereby close said circuit and release said clutch member, said circuit including a slipringandbrushconnectiontosaidslip bowl to maintain electrical connection therewith while the rotary table is in motion.

4. In apparatus for registering movements 01 objects relative to a well, a rotary table adjacent the top of said well, a slip bowl mounted in said rotary table and having an opening therein registering with thebore of said well, a register for registering movements of objects relative to said well, an electro-magnetically releasable clutch member normally placing said register in movement-registering connection with said objects, a normally open electrical circuit connecting said clutch member with said slip bowl, and circuitcloslng means positioned in said slip bowl to close said circuit to thereby release said clutch member, said circuit-closing means comprising a normally open switch member mounted in said slip bowl and having one contact arm thereof yieldably projecting into said opening and adapted to be urged into circuit-closing contact with the other contact arm of said switch member, and slips insertable in said opening in the slip bowl to urge said one contact arm into circuit-closing contact with said other contact arm of the switch member.

5. In apparatus for registering movements of objects relative to a. well, a rotary table adjacent the top of said well, a slip bowl mounted in said rotary table and having an opening therein registering with the bore of said well, a register .for registering movements of objects relative to said well, an electro-magnetically releasable clutch member normally placing said register in movement-registering connection with said objects, a normally open electrical circuit connecting said clutch member with said slip bowl, and circuit-closing means positioned in said slip bowl to close said circuit to thereby release said clutch member, said circuit-closing means comprising a normally open switch member mounted in said slip bowl, said switch member including a first contact an: yieldably projecting into said opening, a second contact arm in circuit-closing relationship to said first contact arm, a; slip ring carried in said slip bowl and connected to said second contact arm, a fixed brush member in said circuit positioned externally of said slip bowl and in electrical contact with said slip ring, and slips insertable in said opening in the slip bowl to urge said first contact arm into circuit-closing contact with said second contact arm.

JOHN T. HAYWARD.

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