US2404132A - Apparatus for use in logging wells - Google Patents

Description

y 1946- J. T. HAYWARD APPARATUS FOR USE IN LOGGING WELLS Filed March 15, 1941 2 Sheets-Sheet 1 w wwg mw LO 0 O O O O O O O O O O O O O O O 0 O O O O O O O 0 0 O O O O O O O O O O O O O O O O O O O O O O O O O O O W msk llllllll ll 9 MEQQ EN Q .16. McAsurflNu & ltSTlNG 3mm: Wu

July 16, 1946. 11 HAYWARD 2,404,132

APPARATUS FOR USE IN LOGGING WELLS Filed March 15, 1941 2 She'ets-Sheet 2 VOLUME UNITS /N WELL 1' I 34 v I I TO PUMP I T J Q JOHN 7. HAYWARD uvmvm A TTORNEYS.

$13. MEASURING it TESTING Patented July 16, 1946 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to the logging of wells and particularly to apparatus for the logging of rotary drilled wells during the drilling thereof.

The Hayward Patent No. 2,214,674, dated September 10, 1940, discloses a method for logging wells during the drilling thereof by the employment of a circulating drilling fluid, wherein increments of the drilling fluid passing through the drilling zone and thence to the top of the well are traced in their passage through the well by measuring the depth of the stratum being drilled at the bottom of the well in synchronism with the rise of the increments from that stratum to the top of the well, so that each increment of the drilling fluid reaching the top of the well may be correlated with that stratum responsible for the presence in that increment of materials charac-' terizing that stratum, the increments reaching the top of the well being tested in various ways for the presence in the fluid of such characterizing materials. In such a method it is important that each increment tested be accurately related to the depth of the stratum to which it refers in order to obtain a true and accurate log of the several strata traversed by the wall and it is also very important that the logging take place during the normal course of drilling of the well in order that the driller may be continuously apprised of the character of the strata being drilled to avoid the ever-present danger of missing strata having oil and gas producing potentialities.

The present invention is directed particularly to improvements in the Hayward method by providing improved apparatus whereby the movement of the drilling fluid increments may be continuously traced in their passage through the well and. automatically and continuously recorded on a chart which is driven in synchronism with the progressive downward movement of the drill in the well, and upon which the several tests of the emerging increments, may be continuously plotted so as to bring them in direct correlation with the depths of the strata to which they refer, to thereby eliminate much labor and to provide a greatly simplified and more accurate log of the well continuously during the actual drilling thereof.

In accordance with the present invention, a chart bearing depth indicia is driven in synchronism with the progressive downward movement of the drill, while a marking device such as a pen or the like is driven in accordance with the volumetric fiow of the drilling fluid through the well and is caused to trace or plot, on the moving chart, the passage of the drilling fluid through the well, or through that part of the well extending from the drilling zone to the top of the well through the annular space between the drilling string and the wall of the well bore.

In accordance with one embodiment of this invention, starting with any given depth of the drilling zone, the volume of drilling fluid flowing through the well is continuously measured and the passage of an increment of the drilling fluid from the drilling zone to the top of the well is traced on the chart by causing the pen or other marking device to initiate a graph on the movin chart at the instant the increment passes 18 the drilling zone depth and then tracing the passage through the well of a volume of drilling fluid equal to the volumetric capacity of the annular space between the drilling string and the well bore for that depth, the graph being caused to 20 terminate when that volume of fluid has passed through the well. By this method the terminal point of the graph will indicate the emergence of that increment from the top of the well. To correlate any test made on that increment with the depth of the drilling zone at the time that increment passed through the drilling zone, it is only necessary to follow back along the graph to the depth on the chart opposite the point of initiation of the graph. A new graph is initiated on the chart immediately upon emergence of one volume of fluid, traced as described, and additional volumes are similarly repeatedly traced on the moving chart to produce a continuous record of the entire well or any portion thereof.

The scale upon which each graph is traced is a scale composed preferably of units of volume and the transverse width of the scale is arranged to represent the volumetric capacity of the well or of the annular space between the drilling string and the well bore, as may be desired.

Since the width of the chart covered by succeeding graphs would become progressively greater as the depth of the well increased and the volumetric capacities became proportionally greater, another embodiment of this invention provides a means whereby these graphs may be confined within a chart section of fixed width, by varying the effective values of the volume units composing the scale upon which the graphs are plotted, in accordance with the change in the volumetric capacities of the well or of the annular spaced referred to.

By tracing on the same chart the records of the several tests made upon the emerging increments of the drilling fluid, in proper relation to the depths at which the tested increments emerge from the well, the actual depths to which the tests refer may be read directly from the chart and the logging operation thereby greatly simplified and made more accurate.

A still more comprehensive log of a drilling well may be made, embodying the apparatus of this invention, by instrumentally recording on the same moving chart other measurements, such as drilling rate, weight on the bit, torque on the drilling string, power required per foot drilled, etc. Such measurements can be and ordinarily are made at the time the formations to which they refer are drilled, and they will, therefore, appear on the chart at the depths to which they properly refer, and can be correlated directly with the information obtained from the circulating fluid.

The important feature in all of these embodiments is the provision, in accordance with this invention, of apparatus for automatically and continuously tracing the passage of increments of the drilling fluid through the well being drilled travels downwardly through the interior of the drilling string to the drilling zone in the vicinity of the bit 'I and thence upwardly through the annular space S between the drilling string and the wall of the well bore to outlet pipe 3, which discharges the fluid back into pit I2 for recirculation through the well. A valved pipe I5 provides means for withdrawing samples of the drilling fluid emerging from the well through outlet pipe 3.

A strip chart, indicated generally by the numeral I6 and of more or less conventional form, is driven in synchronism with the progressive downward movement of the drill bit I in the well,

being connected to the drilling string for this purpose by a drive mechanism I"I driven from the crown block III. The details of the mechon a chart moving in synchronism with the r progressive downward movement of the drill in the well.

By the terms "progressive downward movement of the drill or progressive movement of the drill downwardly in the well is meant,

movements in the well in the normal course of drilling which do not constitute deepening of the well.

The various objects and advantages of this invention will be more readily understood from the following detailed description when read in conjunction with the accompanying drawings which illustrate, more or less diagrammatically, apparatus suitable for practicing the methods of this invention. It will be understood, however,

that this invention is not limited to any particular apparatus, but that various changes may be made in details within the scope of the appended claims, without departing from the spirit of this invention.

In the drawings:

Fig. 1 illustrates, more or less diagrammatically, an assembly of apparatus whereby the passage of drilling fluid through a drilling Well is traced on a chart driven in synchronism with the downward movement of the drill, in accordance with one embodiment of this invention.

Figs, 2 and 3 illustrate, more or less diagrammatically, some of the details of the apparatus shown in Fig, 1, and

Fig. 4 illustrates a portion of a chart produced in accordance with one embodiment of this in- Vention.

Referring to the drawings and Fig. 1 in particular, there is shown a well I, having the usual surface casing 2 with a fluid outlet pipe 3 con-- nected thereto. The usual drilling derrick 4 is mounted over the well and the usual hollow drilling string 5 extends through a rotary table 6 into the well and is provided with a bit I at its lower end and a water swivel 8 at its upper end. 1

The drilling string is operatively suspended in the well from a traveling block 9 which is swung from the usual crown block I0 by means of cables II. Drilling fluid is circulated from the usual mud pit I2 by the usual mud pump I3 through a pipe I4 to the swivel 8, whence the drilling fluid anism I! for driving the chart I6 in synchronism with the downward movement of the drill do not form a part of this invention and any suitable form of drive mechanism'may be employed for this purpose. One such mechanism is illustrated and described in detail in applicants Patent No. 2,326,219, granted August 10, 1943. As stated, however, any other suitable drive mechanism may be employed, it being important only that the chart I6 be caused to move thereby in synchronism with the progressive downward movement of the drill. The chart I 6 is driven at any suitable rate such as, for example, one inch foreach fifty feet of downward progress of the drill.

The drilling fluid being pumped through the well is metered in any suitable way, as by means of a meter I8 mounted in pipe I4, or if pump I3 is of a conventional positive displacement type, it may be employed as a meter for this purpose by suitably connecting thereto a counter I9 to count the stroke cycles of the pump in a manner well understood in this art. The counter I9 may, accordingly, be calibrated to read either units of volume or simply stroke cycles, since with this type of pump, the stroke cycles bear a definite relationship to the volume of fluid pumped, and the number of stroke cycles is equally suitable for the purpose of this invention for measuring the volume of fluid circulated through the well,

The fluid meter, whether meter [8 or counter which is adapted to telemetrically drive a mark- 7 ing device 2I, such as a pen or the like, conventionally used with recorders of the type illustrated generally, which traces a record of the passage of drilling fluid through the well on the moving chart I6, in a manner to be more fully described hereinafter.

The mechanism 20 is illustrated more specifically in Figs. 2 and 3. The fluid meter I8 or counter I9, for example, drives a splined shaft 22 on which is slidably keyed a disk 23,.the rim of which frictionally engages the face of a larger circular plate 24 positioned at right angles to disk 23. Plate 24 is firmly aiiixed to an axial shaft 25 mounted in bearings 26, plate 24 and shaft 25 being rotatable togetherin bearings 26 by the frictional drive imparted thereto from disk 23. The free end of shaft 25 is drivingly connected to the contact arm 21 of a conventional potentiometer 28 to cause the arm 21 to rotate upon a circular resistor 29 (Fig. 3) which is connected in a conventional circuit with a battery 30. The contact arm 21 andresistor 29 are connected by conductors 3|-32 to a conventional recording potentiometer 33a which operates the pen 2| in the conventional manner for electrical recorders, as is well understood by those skilled in the art of these devices. The pen 2| is thus made responsive to the movement of fluid as measured by counter I0, to trace on the moving chart l6 a plurality of graphs G, G1, G2, etc. (Fig. 4), each representing the passage through the well of a volume of fluid equal to the volumetric capacity of the well or of annular space S.

The arrangement of disk 23 on plate 24 constitutes a variable gear ratio connecting shafts 22 and 25, whereby the ratio of the speed of shaft 22 to that of shaft 25 may be varied by varying the radial position of the point of contact of disk 23 with plate 24 relative to the center of the latter. Thus if shaft 22 makes one revolution for each unit accumulated in counter l9, and it is desired to make plate 24 and shaft 25 rotate once for a selected number of units accumulated in counter l9, this may be readily accomplished by selecting a suitable point of contact on plate 24 for disk 23. For this purpose, disk 23 is movable longitudinally along splined shaft 22 by means of an arm 33 which is provided with a pointer 34 which travels along a scale 35 calibrated in units of volumetric capacity of the well. Arm 33 travels along a bracket 36 and is provided with a latch 31 for looking it to the bracket in order to fix the position of disk 23 on plate 24 in accordance with the gear ratio required as determined in terms of the units of scale 35. The units of scale 35 are preferably, though not necessarily, the same as those accumulated in counter l9.

In using this portion of the apparatus, we may assume for purposes of illustration, that the volumetric capacity of annular space S is 500 units of volume. These units may be barrels, gallons, cubic feet, pump cycles, or any other suitable unit. It is desired that the pen 2| make only a single trace across the chart I6 during the passage of a volume of fluid equal to the volumetric capacity of the annular space S and then return to its initial position. The pointer 34 is set at the figure 500 on scale 35, it having been previously determined that at that setting every time 500 units is accumulated in counter I9; the corresponding number of rotations of disk 23 will cause plate 24 to make one complete revolution and this in turn will operate potentiometers 28 and 33a to drive pen 2| across a chart a distance representing the volumetric capacity of annular space S. Completion of a rotation of arm 21 on resistor 29 will operate in the conventional manner to reset pen 2| in its initial position. As the volumetric capacity of space S increases with increasing depth of the well, the position of disk 23 on plate 24 is reset in accordance with the correspondingly increased number of units required to equal this increased capacity. But shaft 25 will still make only one revolution despite the increased number of revolutions required of disk 23. As a result, the width of the scale, that is, the transverse distance over which pen 2| will be driven will remain fixed, the effect of the change in the ratio between the speeds of shafts 22 and 25 being only to change the value of the volume units composing the scale on which the graphs G, G1, etc. are plotted. As a result, the initial and terminal points of each of the graphs will fall on two parallel lines marking the borders of the scale and thereby permit the use of a limited section of the chart for tracing the passage of successive volumes of the drilling fluid through the well, irrespective of any variations in these volumes due to changes in depth of the well.

It will be obvious that any suitable or conventional form of variable gear ratio may be substituted for the elementary form including disk 23 and plate 24 described above.

It will also be understood that where chart space is not a factor, apparatus for mechanically changing the value of the scale units over which pen 2| moves is not necessary and the graphs G, G1, etc. may have difierent lengths corresponding to the particular volumes they represent, it being only necessary to provide more or less conventional means in the recorder mechanism for homing the pen after each volume of fluid, corresponding to a particular depth, has flowed from the well. It will also be understood that various conventional recording mechanisms may be employed for operating the pen, either in a series of strokes all beginning at one side of the chart or passing back and forth across the chart with the passage of consecutive volumes of the fluid, all without departing from the principles or the spirit of this invention.

The complete apparatus above described is employed in the following manner:

For the purposes of this description, counter I9 will be employed, it being understood that meter I8 or any other suitable fluid metering device may be readily substituted therefor, if desired, without altering the principles of the new method. We will assume, for purposes of illustration, that the drill is at a depth of 3000 feet, although it will be evident that the method can be employed from start to finish of the drilling of the well or for any section thereof as may be desired. Since the depth is known, as are the diameters of the well and of the outside and inside of the drilling string 5, the volumetric capacity of the well and of the annular space S can be readily determined for any depth, either by computation or by experimental methods well understood in the art. From these determinations, it can readily be computed how many units must be recorded on counter l9 to represent the passage through v the well of a volume of fluid equal to the volumetric capacity of the well, or of annular space S. For convenience, the latter figure is ordinarily employed, since it is usually desired to trace the movements of increments of the drilling fluid from the drilling zone at the bottom of the well to the top of the well. The total well capacity can also be employed for this purpose by applying to each reading a correction factor corresponding to the volumetric capacity of the hollow drilling string for that depth. Mechanism 20 is then adjusted so that it will cause pen 2| to move once across the chart while that number of units is recorded on counter l9 which represents the passage through, the well of a volume of fluid equal to the volumetric capacity of annular space S for a depth of 3000 feet. The well is filled with fluid and drilling is begun at the same time that circulation of the drilling fluid is started. At the same time, pen 2| will be started on the chart H5 at a point along the depth scale of the chart opposite the figure 3000 and will make its initial impression in (Fig. 4) at that point. This initial impression to will represent the position of an increment of the drilling fluid at the bottom of the well, namely, at a depth of 3000 feet. Now as the drilling and cir- IIVVIII culation of the drilling fluid continue, pen 2| will be actuated by counter I9 operating through the mechanism 20 to move across chart IS in accordance with the displacement of the increment of the drilling fluid upwardly from the bottom of the well through the annular space S and the changing position of the pen will continuously indicate the changing position of the increment relative to the bottom of the well by drawing the graph G. When counter l9 has recorded the passage of the pre-determined number of units, the increment will be emerging from the top of the well and pen 2| will make a final impression g on the chart indicating that point, and by the homing action of the mechanism 20, the penis then caused to swing back to the opposite side of the chart and initiate a new graph G1 tracing the movement of a succeeding volume of fluid through the well. However, during the time required for the increment to move from the bottom to the top of the well, the drill bit I will have progressed some distance below the original 3000 foot depth by a variable distance depending upon the relative hardness of the formations, the rate of drilling, etc. Chart IE will have moved longitudinally a corresponding distance, as a result of which the right hand end of the graph G will appear on the chart opposite some depth figure greater than 3000 feet,

say 3020 feet. A test taken of the increment of the fluid emerging from the well and recorded on the chart at that time will, therefore, appear at the greater depth. However since the graph G now connects the initial and final points a: and y, it is only necessary to follow the graph back from y to a: to determine the true depth to which the test taken at y actually refers.

Fig. 4 illustrates a, portion of a chart, made in accordance with this invention, bearing a plurality of successive graphs G, G1, G2, G3, etc., representing the passage of a plurality of successive increments of the drilling fluid from the bottom to the top of the well. The initial points of each of these graphs appear opposite a depth figure which represents the depth of the well at the time each of the increments started from the bottom of the well, while the opposite ends of each graph appear at some greater depth. Of

course, since the graphs represent consecutive volumes of fluid, the end of one graph will coincide with the beginning of the next succeeding graph relative to a depth position recorded on the depth scale. That depth will be the depth at which the preceding increment emerges from the well as a new increment represented by the second graph begins its passage up the well from that depth. Records of the tests made for oil and gas on the emerging increments of the drilling fluid comprise the traces O and H, respectively, drawn on the chart in parallel columns adjacent the terminal ends of the graphs G, G1, etc., since these tests are necessarily made on the emerging increments. Thus, in order to find the true depth of an all show which appeared, for example, at O1 opposite a depth of 3072 feet, which is the depth at which graph G3 terminates, it is only necessary to follow this graph back to the point of its initiation to find that the increment tested for oil at 01 left the bottom of the well at 3045 feet.

With an apparatus of logging in accordance with this invention, it is not necessary that the test of the emerging drilling fluid fall exactly opposite the terminus of one of the graphs G, G1, etc., in order to determine the actual depth to which that test refers. For example, suppose it is desired to find the true depth to which a test 02 refers, which is taken on the emerging fluid when the depth of the well is 3135 feet. This test falls on chart l6 between two of the graphs Gs and G7 and no graph appears on the chart by which the true depth can be directly located. However, the true depth can be located from the chart by drawing a horizontal line corresponding to the depth of 3135 feet opposite 02 until it strikes the graph G7. From the point of intersection with G7 a line is drawn vertically until it intersects the graph G6, whence a horizontal line is drawn to intersect the depth axis, giving the true depth of about 3122 feet as the depth of the well when the tested fluid left the, bottom. By means of the chart, produced by the apparatus of this invention, the emerging fluid can be tested at any time and the test referred directly to the true depth which it represents.

It will be obvious that, as the volumetric capacity of the well and of space S increases with increasing depth, graphs G, G1, etc., will normally lengthen correspondingly. However, by the provision of a scale changing device such as mechanism 20, the graphs will all be confined within a strip on the chart of fixed width, irrespective of the changes in volume and without affecting the accuracy of the record.

By logging wells in the manner described, various logging tests may be plotted on the same chart and all the various characteristics of the formations penetrated by the drill, as determined for logging purposes, will appear directly on the chart in properly correlated relationship. For example, referring to Fig. 4, the drilling rate is continuously traced in a graph D along side the depth index. Since this graph is ordinarily obtained from the mechanical reactions of the drill as it progresses through the earth strata, its values will appear directly opposite the true depths to which these these values refer. Traces O and H, which represent the values of oil and gas, respectively, in the emergin drilling fluid, will appear, as shown, opposite the depths at which the tested increments of the drilling fluid emerge, but as previously described, by means of the graphs G, G1 G2, etc. These values can be directly correlated with the true depths and with the corresponding values of the drilling rates, at each of these depths, and the drilling rates, therefore, become of special value as an additional check of the oil and gas strata, since these are normally softer than other adjacent strata and are generally clearly evidenced in the drilling rate graph. The traces of the Drilling Rate and of Oil and Gas may be placed on the record in any suitable manner.

It is ordinarily not necessary to continuously change the scale representing the volumetric capacity as the depth changes, although this may be done if desired. Usually, the scale is changed at some suitable interval of increasing depth, such as at every 20 feet or every 50 feet, or at any other suitable interval, depending upon the depth of the well. For example, if a well is drilling at 3000 feet, an increase in depth of as much as 30 feet will produce a change in volumetric capacity of the well of only one percent, and since the fluid circulates at high rates, often as much as several hundred barrels per foot drilled, the resulting error in correlating the tests of the outgoing fluid with the true depth will ordinarily be only a small fraction of one percent, which is a very high degree of accuracy.

From the foregoing it will be evident that this invention provides apparatus by which a complete and accurate log may be made continuously during the rotary drilling of a well.

What I claim and desire to secure by Letters Patent is:

1. An apparatus for logging the strata of a well while being drilled by the employment of a hollow rotary drill string and a fluid circulated down said string and up outside thereof to the surface, comprising, the combination with means cooperating with the drill string for measuring the depth of a stratum being drilled, of means cooperating with the depth measuring means for measuring the rise ofa selected increment of the fluid from said stratum.

2. An apparatus for logging the strata of a well while being drilled by the employment of a hollow rotary drill string and a fluid circulated down said string and up outside thereof to the surface, comprising, th combination with chart means driven by said drill string to move in synchronism with the progressive downward movement thereof through said strata, of means for measuring the volume of said fluid flowing through the well, and marking means cooperating with said measuring means for tracing on the moving chart the records of the rise of selected increments of said fluidfrom each of said strata to the surface.

3. In combination with rotary well drilling apparatus includin a hollow rotary drill string and means for circulating drilling fluid through the well, depth recording means driven by said drill string to move in synchronism with the progressive downward movement of said drill string, means for measuring the vol me of drilling fluid flowing through the well, mar ing means operatively associated with said recording means and responsive to the flow of the drilling fluid through said measuring means to plot on said recordin means the record of the passage of said fluid through the well relative to the changing depth thereof,

4. In combination with rotary well drilling apparatus including a hollow rotary drill string and means for circulating drilling fluid through the well, depth recording means driven by said drill string to move in synchronism with the progressive downward movement of said drill string, means for measuring the vol of drilling fluid flowing through the well, marki g means operatively associated with said recording means and responsive to the flow of the drilling fluid through said measuring means to plot on said recording means the record of the passage of said fluid through the well relative to the changing depth thereof, and limiting means operatively associated with said marking means and responsive to the passage of a pre-determined volume of said fluid through said measuring means to correspondingly limit the total distance moved by said marking means relative to said recording means.

5. In combination with rotary well drilling apparatus including a hollow rotary drill string and means for circulating drilling fluid through the well, depth recording means driven by said drill string to move in synchronism with the progressive downward movement of said drill string, means for measuring the volume of drilling fluid flowing through the well, marking means having a variable ratio drive connection with said measuring means and respo sive to the flow of the drilling fluid through sai \measuring means to plot on said recording means the record of the passage of said fluid through the well relative to the changing depth thereof, and

limiting means operatively associated with said marking means and responsive to the passage of a pre-determined volwfle of said fluid through said measuring means to correspondingly limit the total distance moved by said marking means relative to said recording means, said drive connection including means for varying the drive ratio between said measuring means and said marking means in proportion to changes in said pre-determined volumes.

6. In combination with rotary well drilling apparatus including a hollow rotary drill string and means for circulating drilling fluid through the well, depth recording means driven by said drill string to move in synchronism with the progressive downward movement of said drill string, means for measuring the vol of drilling fluid flowing through said well, marking means operatively associated with said recording means and responsive to the flow of fluid through said measuring means to successively plot on said recording means relative to the changing depth of the well the records of the passage of successive pre-determined volumes of said fluid through said well.

7. In combination with rotary well drilling apparatus including a hollow rotary drill string and means for circulating drilling fluid through the well, depth recording means driven by said drill string to move in synchronism with the progressive downward movement of said drill string, means for measuring the volume of drilling fluid flowing through said well, marking means having a variable ratio drive connection with said measuring means and responsive to the flow of fluid through said measuring means to successively plot on said recording means relative to the changing depth of the well the records of the passage of successive pre-determined volumes of said fluid through the well, and limiting means operatively associated with said marking means and responsive to the passage of each of said pre-determined vol es of said fluid through said measuring cans, to limit in proportion to each of said pre-determined volumes the distance moved by said marking means relative to said recording means, said limiting means including means for varying the drive ratio of said drive connection between said measuring means and said marking means in proportion to changes in said pre-determined volumes, to thereby uniformly limit said distance moved by said marking means for all of said volumes.

8. In combination with a, well being drilled by the employment of a hollow rotary drill string and a fluid circulated down said string and up outside thereof to the surface, apparatus for plotting the passage of increments of said fluid through said well relative to the changing depth of the well, comprising, a chart driven by said drill string to move in one direction in synchronism with the progressive downward move ment of said drill string, said chart bearing a scale of depth measurement extending in said direction, means for circulating said fluid through the ell, measuring means for measuring the voluxfil of fluid passing through the well, marking eans responsive to the flow of the fluid through said measuring means to move across said chart generally transversely relative to the direction of movement of said chart from a point along said depth scale corresponding to the bottom of the well, drive means operatively connecting said measuring means to said marking means and including means for terminating the transverse movement of said marking means upon passage through the well of a predetermined volume of the fluid required to displace an increment thereof from the bottom of the well to the surface, and for then initiating a new transverse movement for the next succeeding increment.

9. In combination with a well being drilled by the employment of a hollow rotary drillstring and a fluid circulated down said string and up outside thereof to the surface, apparatus for plotting the passage of increments of said fluid through the well relative to the changing depth of the well, comprising, a chart driven by said drill string to move in one direction in synchronism with the progressive downward movement of said drill string, said chart bearing a scale of depth measurement extending in said direction, means for circulating said fluid through the well, measuring means for measuring the volume of fluid passing through said Well, marking means responsive to the flow of said fluid through said measuring means to draw a series of lines across said chart in a direction generally transverse relative to the direction of movement of said chart and initiated from a plurality of points along said depth scale, each of said lines tracing the passage of a'pre-determined volume of said fluid required to displace an increment of the fluid to the surface from the depth represented by the point of initiation of that particular line, drive means connecting said measuring means to said marking means and operative to cause the latter to initiate each of said lines at a point along said depth scale correspondingto the end of the next succeeding line.

10. In combination with a well being drilled by the employment of 3 a hollow rotary drill string and a fluid circulated down said string 12 and up outside thereof to the surface, apparatus for plotting the passage of increments of said fluid through the well relative to the changing depth of the well, comprising, a chart driven by said drill string to move in one direction in synchronism with the progressive downward movement of said drill string, said chart bearing a scale of depth measurement extending in said direction, means for circulating said fluid through the well, measuring means for measuring the volume of fluid passing through said well, marking means responsive to the flow of said fluid through said measuring means to draw a series of lines across said chart in a direction generally transverse relative to the direction of movement of said chart and initiated from a plurality of points along said depth scale, each of said lines tracing the passage of a pre-determined volume" of said fluid required to displace an increment of the fluid to the surface from the depth represented by the point of initiation of that particular line, drive means connecting said measuring means to said marking means and operative to cause the latter to initiate each of said lines at a point along said depth scale corresponding to the end of the next succeeding line, said drive means including a variable gear ratio means for varying the drive ratio between said measuring means and said marking means in proportion to the change in volume of said well due to the change in depth thereof.

11. Apparatus for measuring and recording vnlume's' of well-drilling fluid circulating down a" drill string and upwardly outside thereof, com prising, a fluid flow meter, a recorder having cooperating elements one of which is synchronized with the drill string, and a variable gear ratio for driving the other element of said recorder from 40. the flow meter.

JOHN T. HAYWARD.

Images