WO1993005366A2

WO1993005366A2 - Mass flow meter

Info

Publication number: WO1993005366A2
Application number: PCT/CA1992/000364
Authority: WO
Inventors: Daniel Guy Pomerleau; Guy Pomerleau; Alain Ducated
Original assignee: TRIDENT CREATIVE TECHNOLOGY Inc
Current assignee: TRIDENT CREATIVE TECHNOLOGY Inc
Priority date: 1991-08-30
Filing date: 1992-08-28
Publication date: 1993-03-18
Anticipated expiration: 1994-02-28
Also published as: AU2472992A; WO1993005366A3

Abstract

The invention relates to an apparatus for continuously determining the variation in weight of fluent bulk material and more particularly, in detritus in drilling fluid discharged during a well drilling operation where drilling fluid discharged from the borehole is passed through a shale shaker (5) to remove the detritus. The apparatus has a plurality of receptacles (82), each of which are supported on a device (84) for sequential movement to and through a detritus receiving position. A mesuring device (90) is operatively connected to measure the weight of detritus collected in a selected receptacle and produces an output in response to the weight of detritus measured. A lock device (92) is operatively associated with the supporting device for maintaining a selected receptacle in the receiving position for receipt of detritus, the lock device being releasable when the weight in the selected receptacle reaches a predetermined weight to allow the support device to move under the weight of detritus in the receptacle away from the receiving position while at the same time a receptacle moves into the receiving position.

Description

MASS FLOW METER

Field of the Invention

This invention relates to a method and system for continuously monitoring the variations in weight of fluent bulk material and particularly where the material is the amount of detritus, including cuttings sloughings or cavings, and other material, including contaminated drilling fluid and lost circulation material picked up by, or entrained in, a water or oil based drilling fluid being circulated in a subterranean well or excavation (Wellbore) during the drilling process into subterranean formations, circulated to the surface, and separated from the drilling fluid by a vibrating screening device ("shale shaker" is the generic term for a line of devices serving this purpose) and subsequently discharged from the fluid circulating system.

Background of the Invention

As is well known, drilling fluids are employed when drilling holes into subterranean formations. The drilling fluid, usually referred to as drilling mud, consists of a mixture of fluids such as water, air hydrocarbons, vegetable oils and other organic and inorganic materials. These materials may be used individually or in admixture and optimized for special properties to better perform some or all of the following functions; though not limited to same:

1. To provide a viscous medium which will facilitate the transport of cuttings to the surface.

2. . To provide a hydrostatic pressure which will control or prevent the uncontrolled entry of subterranean formation fluids into the wellbore.

3. To provide cooling and lubrication to both the drilling bit and the drilling string.

4. To suspend cuttings in the wellbore during the cessation of the drilling and circulating process. 5. To reduce the damage to subterranean formations which may contain hydrocarbons or other fluids of interest.

6. To provide an aid to subterranean formation evaluation.

The drilling fluid is circulated into the wellbore by pumping the fluid down the hollow rods or drill pipes which are lowered into the well during the drilling process. The drill pipes are connected to a drilling "bit" through which the drilling fluid exits. The fluid subsequently returns to the surface through an annular space surrounding the drillpipes and the inner surface of the excavated wellbore (borehole wall). In an alternative mode of drilling circulation the drilling fluid is pumped down the annulus and returns up the drillpipes; this is known as reverse circulation.

During the circulation process detritus, including cuttings, sloughings or cavings and other material, circulating contaminated drilling fluid and lost circulation material is "picked up" by the circulating fluid; either at the face of the drill bit or further up the wellbore; and returned to the surface for separation from the drilling mud and subsequent disposal. The effective removal of such detritus or cuttings, cavings, sloughings and millings from the drilling fluid contributes to the maintenance of the condition of the drilling fluid.

The ability of the drilling fluid to effectively transport the detritus generated by the excavation process is fundamentally critical to the successful completion of a drilling project. Ineffective transport results in, or contributes to, drill pipes becoming stuck in the borehole, increased torque in rotary drilling operations with subsequent "twist off (breakage of a drillpipe) and damage to potential producing reservoirs. As a result an exceptional amount of time and effort has been invested in the study of "Hole Cleaning" and related topics. For instance the rheology of drilling fluids, by the energy exploration industry. This topic is especially important since the advent of the use of horizontal drilling techniques which suffer from severe problems directly associated with the difficulty in effectively removing detritus from the wellbore. The ability to monitor the variance in cuttings discharged at the surface, in response to such parameters as drilling rate, variations in fluid Theological parameters, variations in circulating rate, variations in fluid density, effects of controlled or uncontrolled deviation, or as a result of sloughing or caving, will allow for real time optimization of drilling, or drilling fluid engineering. The ability to monitor the aforementioned variances further enhances the effort to improve the drilling art and to prevent catastrophic failure of a drilling project.

The present invention provides a continuous, qualitative method of determining not only the hole cleaning potential of the drilling fluid, but the effectiveness or result of variations in all parameters involved in cuttings transport; ie. circulating rate or fluid velocity, fluid density, rheology, annular space, deviation, rate of deviation, etc. By using real time monitoring of the effects of these parameters significant steps may be taken towards optimizing these parameters for both vertical and highly deviated excavations.

We are aware of a patent which relates to a similar art, namely U.S.

Patent No. 4,413,511 of John K. Godbey which is assigned to Mobil Oil Corporation, that Patent being entitled "System for Measuring Cuttings and Mud Carryover During the Drilling of a Subterranean Well". Godbey discloses a method and system for continuously measuring the amount of solid cuttings picked up by a drilling mud being circulated in a well being drilled into a subterranean formation and the amount of drilling mud carried over with the cuttings when the cuttings are separated from the drilling mud by a shale shaker. Godbey, by his method and system as described in U.S. Patent No. 4,413,511 seeks to accurately quantify the exact amount of detritus being delivered to the surface during the drilling operation. The system described by Godbey is quite complex and costly to operate; and because of this, its application to drilling operations is very limited. As a result, systems for the continuous monitoring of the delivery of cuttings and other detritus to the surface during drilling operations do not appear to be currrently in use. The present invention, in contrast to that described by Godbey, only monitors trends in delivery of detritus in drilling fluid to the surface i.e. whether the delivery is steady or whether it is increasing or decreasing.

Summary of the Invention

This invention seeks to provide a method and apparatus for continuously monitoring the volume of fluent bulk material being discharged from an industrial process and more particularly detritus being discharged from a well during an excavation or a subterranean well drilling process.

In accordance with this invention there is provided an apparatus for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, the apparatus comprising: means for collecting said bulk material; measuring means operatively connected to measure the weight of bulk material collected by said means for collecting and for producing an electrical output in response to the weight measured; means for selectively discharging said material from said collecting means; and means for monitoring the variation in electrical output from said measuring means, said output being indicative of the variation of material collected.

A further embodiment of the invention provides for a method for continuously deteπnining the variation in weight of fluent bulk material discharged during an industrial operation, the apparatus comprising:

(a) collecting the bulk material in a collecting means;

(b) producing an electrical output in response to the weight measured by measuring means operatively connected to the collecting means;

(d) monitoring the variation in electrical output from the measuring means, the output being indicative of the variation of material collected in the collecting means;

(c) discharging the material from the collecting means; and (e) continuously repeating steps (a) to (d).

In accordance with a further embodimment of this invention there is provided an apparatus for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, the apparatus comprising: a plurality of receptacles; means supporting the receptacles for sequential movement to and through a bulk material receiving position; measuring means operatively connected to measure the weight of bulk material collected in a selected receptacle and for producing an output in response to the weight measured; and lock means operatively associated with the supporting means for maintaining a selected receptacle in the receiving position for receipt of bulk material, the lock means being releasable when the weight in the selected receptacle reaches a predetermined weight to allow the support means to move under the weight of bulk material in the receptacle away from the receiving position while at the same time a subsequent receptacle moves into the receiving position.

A still further embodiment of the invention provides for a method for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, the method comprising the steps of: (a) moving a support means which supports a plurality of receptacles for sequential movement of the receptacles to and through a bulk material receiving position;

(b) measuring the weight of bulk material collected in the selected receptacle by a measuring means operatively connected thereto; (c) maintaining the selected receptacle in the receiving position by a locking means operatively associated with the support means;

(d) releasing the locking means when the weight in the selected receptacle reaches a predetermined weight and allowing the support means to move under the weight of bulk material in the receptacle away from the receiving position, while at the same time allowing a subsequent receptacle to move into the receiving position; and (e) continuously repeating steps (a) to (d).

Another embodiment of the invention provides a method for continuously deteπnining the variation in detritus in a drilling fluid discharged during a well drilling operation; comprising the steps of: (a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus;

(b) returning the drilling fluid from which the detritus has been removed by the shale shaker to the well drilling operation;

(c) passing the detritus via a conveyor means over a weighing means connected to at least one load cell, whereby variations in weight of the conveyed detritus cause variations in stress on the at least one load cell; and

(d) continuously monitoring the variation in electrical output produced by the load cell(s) as a function of the variations in weight of the detritus.

A further embodiment of the invention provides for a method for continuously determining the variation in detritus in a drilling fluid discharged during the drilling operation; comprising the steps of:

(a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus; the shale shaker including a spring mounted vibrating screen, at least one load cell being located beneath, and connected to a spring or springs on which the screen is mounted whereby variations in weight of the detritus passed over the screen cause a variation in stress on the load cell(s);

(b) returning the drilling fluid from which the detritus has been removed by the shale shaker to the well drilling operation; and (c) continuously monitoring the variation in electrical output produced by the load cell(s) as a function of the variations in weight of the detritus passed over the screen.

A still further embodiment of the invention provides for a method for continuously determining the variation in detritus in a drilling fluid discharged during a well drilling operation; comprising the steps of: (a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus; the shale shaker including a spring mounted vibrating screen beneath which are positioned a plurality of means for measuring change in rate of velocity and the means for measuring being operatively connected to the vibrating screen;

(b) returning the drilling fluid from which detritus has been removed by the shale shaker to the well drilling operation; and

(c) continuously monitoring the variation in the velocity of the vibrating screen as a function of variations of weight of the detritus passed over the screen.

A still further embodiment of the invention provides for a method for continuously determining the variation in detritus in a drilling fluid discharged during a well drilling operation; comprising the steps of:

(a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus; (b) returning the drilling fluid from which the detritus has been removed by the shale shaker to the well drilling operation;

(c) passing the detritus to a trough means, the trough means including at least one load cell operatively connected thereto, whereby upon the weight of the detritus collected in the trough means reaching a predetermined limit as measured by the load cell, triggering a release means operatively connected to the trough for discharging the detritus from the trough;

(d) continuously monitoring the variation in electrical output produced by the load cells as a function of the variation in weight of the detritus; and (e) continuously repeating steps (a) to (c).

A still further embodiment of the invention provides for an apparatus for continuously determining the variation in detritus in a drilling fluid discharged during a well drilling operation where drilling fluid discharged from the borehole is passed through a shale shaker to remove the detritus, the apparatus comprising: a trough means for receiving the detritus from the shaker; a load measuring means operatively connected to the trough means for producing an output indicative of the weight of detritus collected in the trough means; and release means operatively connected to the trough for discharging the detritus from the trough upon the weight of the detritus reaching a predetermined limit.

Brief Description of the Drawings

In the drawings wherein like numerals indicate like parts, illustrative embodiments of this invention are shown. A listing and brief description of each drawing is given below.

Figure 1 is a diagrammatic vertical cross-section of a drilling rig and excavation or borehole, showing the drilling fluid circulating paths; Figure 2(a) is a top view of a shale shaker; Figure 2(b) is a side view of the shale shaker in Figure 2(a); Figure 2(c) is a side view of a conveyor for use with the shale shaker of figure 2;

Figure 3(a) is a side view of one embodiment of a drilling fluid processing unit according to the present invention;

Figure 3(b) is a top view of the embodiment illustrated in Figure 3(a); Figure 3(c) is a side view of a receptacle according to the present invention;

Figure 4(a) is a top view of a further embodiment of the invention; Figure 4(b) is a side view of a conveyor of Figure 4(a); Figure 5(a) is a top view of a further embodiment of the present invention; and Figure 5(b) is a side view of the embodiment illustrated in Figure 5(a).

Description of the Preferred Embodiments The invention relates to methods for monitoring the qualitative variations in the delivery of detritus; from an excavation or wellbore produced during the drilling process, after or during its separation by a shale shaker. By using this invention or method of continuous monitoring of the detritus delivery, a subsequent monitoring of the factors controlling detritus delivery will be achieved, namely; the effects of; Rheology, Fluid Density, Fluid circulating rate, variations in well bore diameter, variations in both hole inclination, rate of change of hole inclination, etc.

Referring to the diagram in Figure 1, a vertical cross-section of a drilling rig and excavation or borehole, along with the drilling fluid circulating paths is indicated generally by numeral 1. A well is drilled or excavated into a subterranean formation 12. Drilling fluid 11 is circulated down the drill pipes or drill string 14. The drilling fluid 11 is then passed through openings or jets in a drill bit or hammer 15 and is returned to the surface through an annular space 16 between the well wall 10 and the drill string 14. The drilling fluid 11 picks up detritus produced by the drill bit 15, along with detritus, cavings, sloughings, and such like from the borehole wall and transports this detritus from the well 10 via a pipeline 18 to a shale shaker 3 shown in Figure 2(a).

Referring to Figures 2(a) and (b), the shale shaker 3 has an adjustable deck angle and is capable of a lateral shaking motion. The drilling fluid 11 and detritus received from line 18 is discharged into the shaker and evenly distributed through channels 4 onto a vibrating screen 5. In the majority of cases virtually all the drilling fluid 11 passes through the screens 5 immediately. A small amount of the fluid is however retained on the detritus. As the detritus and the retained fluids pass along the vibrating screen 5, a significant proportion of the drilling fluid is removed from the detritus and passes through the vibrating screens 5 and into a receiving tank or pit (not shown) that may be located under the shale shaker 3. The drilling fluid is then subsequently processed and then recirculated down the well bore via the drillstring 14, or immediately recirculated depending on the complexity of the drill string in use. The detritus, is discharged onto a low friction surface, sloping ramp 8 and then subsequently slides off to be collected by a suitable receptacle. An embodiment of the present invention is shown in figure 2(c), in which the detritus from the sloping ramp 8 slides onto a conveyor belt 9 which is rotated at a constant or variable velocity X by a belt driver 10. The conveyor belt 9 then transports the detritus down its length at this constant or variable speed to a point directly above an idler pulley 12 as more clearly indicated in Figure 2(c). This pulley is termed a weighing idler. The weighing idler 12 is connected to a load cell 11. Variations in the weight of the detritus as a result of variations in volume of detritus will then be monitored as a result of variations in Stress on the load cell 11 in response to the movement of the weighing idler 12. When the conveyor 9 is operated with a constant velocity then the variations in loading on the load cells 11 may be output directly through a conditioning amplifier to a Chart Recorder, (not shown) personal Computer, or voltmeter or any other device designed to translate the variations in electrical output Δv produced by the load cell 11 to a weight reading. When detritus is delivered to the conveyor 9 at a variable rate the conveyor 9 is operated with a variable speed drive in response to this variable dehvery speed. In this case variations in load cell 11 signal will require not only conditioning but also processing by software or pre-programmed hardware to take into consideration the variance in dehvery rate of detritus to the load cells 11 as a result of conveyor belt velocity changes. The equation which would be used to deal with this is

Dv = Λv/X where

Dv = Variations in load cell electrical output

X = Velocity of the conveyor belt at any time (t_n) when a όv is measured at points 11 on the conveyor 9.

Referring to Figures 3(a) and 3(b), an embodiment of the invention is shown in which, an apparatus for continuously monitoring the variation in detritus from a well drilling operation is shown generally by numeral 80. The sloping ramp 8 of the shale shaker is shown positioned over a receptacle or tray 82. A pair of spaced apart supports 84 each have a pivot point 86 for pivotally supporting a beam

96 therebetween. Support arms 88 are attached to the beam 96 and extend radially each at approximately 90° to each other. The support arms are arranged in groups of four and with each group spaced on the beam in a plane perpendicular to the length axis of the beam 96. The receptacle or tray 82 is mounted on one side of each of the four arms 88. It can been seen from Figure 3(a) that as the support arms 88 are rotated with respect to the supports 84, each of the trays 82 are sequentially positioned below the outlet of the sloping ramp 8. A control box 90 housing a latching device 92 and a load measure device is also attached between the supports 84, but on a side opposite to that of the shale shaker.

Referring now to Figure 3(b), a top view of the apparatus 80 shows more clearly the locking device 90 and its operation. The latching device 90 comprises a locking pin activated by a solenoid. The locking pin 92, in an extended position, is positioned over a support box 88. The receptacle or tray indicated by numeral 94 receives the detritus from the shale shaker, the weight of the detritus in the tray 94 translates to an upward force on the locking pin 92 with the pin extended and the trays 88 are prevented from rotating. By retracting the pin 92 the trays are allowed to rotate and thus tray 94 discharges its contents. These trays may be made of narrow gauge aluminum sheet or any other suitable material, such as plastics, and are concavely curved to receive the detritus. The brackets 88 are mounted on a rectangular cross-section beam 96.

Referring to Figure 3(c), the rectangular beam and mounting of the brackets 88 can more clearly be seen. Each of the brackets 88 are attached to the beam 96 to radiate from each of the vertices of the beam 96. The beam 96 is pivotally mounted on the support 94 by means of a cylindrical steel axle 98 which inserts into an axle slot 100 in the beam 96. The other end of the axle 98 is fitted into the pivot 86 of the support 84. The support arms 88 are attached to the beam 96 by an L-shaped bracket having holes drilled therethrough. Allan screws may be inserted through these holes to secure the brackets 88 to the beam 96.

Referring back to Figure 3(a), the operation of the device may be more clearly explained. The support 84 is positioned so that a tray 82 is positioned to receive detritus from the ramp 8 of the shaker. As detritus collects in the selected tray 82, a load cell in the control box 90 measures the torque produced on the beam 88 which supports the tray 94. This force exerted on the load cell produces a current variation at the load cell output which may be amplified by an amplifier 106 and subsequently passed to a plotter, a chart recorder, Voltmeter or computer (now shown). A comparator circuit 110 is connected to a seize signal from the amplifier 106. The output of the comparator 110 produces an output signal when the signal at its input reaches a preset value X. This output signal may be used to trigger the solenoid housed in the control box 90 and which maintains one of the trays in the selected position. The solenoid arm 92, as clearly indicated in Figure 3(b), may be retracted to allow the axle carrying the trays to rotate under the weight of the detritus in the tray 82 whereby the detritus in the tray is discharged as it rotates through 90°. It may be seen that in this time the solenoid is released to lock the arm as it rotates through 90° to bring the next empty tray in position to receive detritus from the shaker.

Referring to figures 4(a) and 4(b), the shale shaker 3 is indicated as in Figure 2. The drilling fluid and detritus received from the line 18 is discharged into the shaker and evenly distributed through channels 4 onto the vibrating screen 5. In the majority of cases virtually all the drilling fluid passes through the screens immediately with a small amount retained on the detritus. With regard to the embodiment shown in figure 4(a) load cells 6 are located at the screen damper supports. As the detritus and the retained fluids pass along the vibrating screen 5, the loading on the shaker screens may be detected with these load cells 6, a significant proportion of the drilling fluid is removed from the detritus and passes through the vibrating screens 5 and into a receiving tank or pit (not shown) that may be located under the shale shaker 3. The drilling fluid is subsequently processed and then recirculate down the well bore via the drills tring 14, or immediately recirculated depending on the complexity of the drilling rig in use.

By monitoring the variation in electrical output of the load cells 6 located either; at all spring damper locations around the shaker box that holds the shaker screens 5, or at the two locations furthest from the channel region 4, where the drilling fluid is distributed onto the shaker screens. It is possible to monitor the variation in delivery rate of detritus from the wellbore or excavation. By monitoring the detritus delivery in this fashion data errors introduced by the sloping ramp 8 of Figure 2 and the sloping ramp 24 in Figure 2 of Godbey's patent 4,413,511 is eliminated, and a clearer picture of detritus delivery rate is monitored. The electrical output variations produced by the load cells 6 will be passed through a conditioning amplifier and may then be output through a chart recorder, volt meter, personal computer or other such device capable of monitoring variations in electrical output.

Referring to the embodiment shown in Figure 4(b), the loading on the shaker screens is detected by accelerometers 7. The accelerometers are located either at all spring damper locations around the shaker box that holds the shaker screens 5, or at the two locations furthest from the channel region 4 where the drilling fluid is distributed onto the shaker screens. By monitoring the variation in electrical output of the accelerometers 7; which will vary their output directly with changes in shaker acceleration resulting from changes in detritus loading on the shaker screen 5, located either at all spring damper locations around the shaker box that holds the shaker screens 5, or at the two locations furthest from the channel region 4 where the drilling fluid is distributed onto the shaker screens; it is possible to monitor the variation in delivery rate of detritus from the wellbore or excavation. By monitoring the detritus delivery in this fashion the data errors introduced by the sloping ramp 8 in Figure 2 and the sloping ramp 24 in Figure 2 of Godbey's patent 4,413,511 is eliminated, and a clearer picture of detritus delivery rates is monitored.

The electrical output variations produced by the accelerometers 7 will be passed through a conditioning amplifier and may then be output through a chart recorder, volt meter, personal computer or other such device capable of monitoring variations in electrical output.

With regard to the embodiments shown in Figures 5(a) and 5(b), a receiving trough 50 is positioned at the outlet of the vibrating screen 5. The trough is mounted at the end of one of the arms of a series of parallel L-shaped bars 50'. A box or support is shown by numeral 65 having a shaft 51 at an upper end thereof The bars 50' are pivotally mounted, at the knee of the L, on the shaft 51, allowing the trough to swing between a receiving and a discharge position. A load cell 53 is attached to the box 65 at a position in proximity to the free arm of the bars 50' and in a region indicated by numeral 55. An electromagnet 52 is rigidly attached to the load cell 53 so as to exert a magnetic force on the bar 50' at the region 55. This force holds the trough in its receiving position.

Detritus discharged into the trough exerts a downward force and an upward force on the bar at point 55. The upward force at 55 initiated by detritus loading at 50 causes an excitation in the load cell 53 this excitation is related as a small current variation which is amplified by an amplifier 56 and plotted or monitored by a chart recorder, voltage meter, or computer 61. An enhancement of the device includes a comparator 58 circuit which eliminates the manual release of detritus from 50. A signal is received from the amplifier 56 and passed through a conditioning filter 57 and on to the comparator 58 which monitors the received voltage for a reference value stored/set in 59. At some preset value Z the electromagnet actuator 60 disconnects current to the electromagnet 52, allowing the detritus to be discharged from 50 by permitting the downward movement of the trough 50 to a point where gravity will allow the detritus to discharge itself. This downward movement of the trough 50 allows the pivoting bar 51 to move its opposite end 55 up to a point in contact with an electromagnet 54 where it may be temporarily held for a preset time, to allow the cuttings to completely discharge from the trough 50. After a time t the current from the actuator 60 to the electromagnet

54 is suspended and the pivoting bar 51 is allowed to return to its receiving position. The cycle is then repeated continuously.

The data collected by these methods can be used not only to provide continuous, qualitative method of determining not only the hole cleaning potential of the drilling fluid, but the effectiveness or result of variations in all parameters involved in cuttings transport; ie. circulating rate or fluid velocity, fluid density, rheology, annular space, deviation, rate of deviation, etc. By using real time monitoring of the effects of these parameters significant steps may be taken towards optimizing these parameters for both vertical and highly deviated excavations. A graph (not shown) of volume of cuttings vs depth may be plotted which may be used to identify areas of the borehole which may be "washed out" (a condition where the diameter of the actual bore hole is substantially larger than the diameter of the excavating drill bit). By identifying such locations in the well during the drilling process, remedial steps may be taken to deal with these troublesome hole sections.

While the invention has been described in connection with a specific embodiment thereof and in a specific use, various modifications thereof will occur to those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.

The terms and expressions which have been employed in the specification are used as terms of description and not of limitations, and there is no intention in the use of such terms and expressions to exclude any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims to the invention.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An apparatus for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, the apparatus comprising: means for collecting said bulk material; measuring means operatively connected to measure the weight of bulk material collected by said means for collecting and for producing an electrical output in response to the weight measured; means for selectively discharging said material from said collecting means; and means for monitoring the variation in electrical output from said measuring means, said output being indicative of the variation of material collected.

2. A method for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, the apparatus comprising:

(a) collecting said bulk material in a collecting means;

(b) producing an electrical output in response to the weight measured by measuring means operatively connected to said collecting means;

(d) monitoring the variation in electrical output from said measuring means, said output being indicative of the variation of material collected in said collecting means;

(c) discharging said material from said collecting means; and

(e) continuously repeating steps (a) to (d).

3. An apparatus for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, said apparatus comprising: a plurality of receptacles; means supporting said receptacles for sequential movement to and through a bulk material receiving position; measuring means operatively connected to measure the weight of bulk material collected in a selected receptacle and for producing an output in response to said weight measured; and lock means operatively associated with said supporting means for maintaining a selected receptacle in said receiving position for receipt of bulk material, said lock means being releasable when said weight in said selected receptacle reaches a predetermined weight to allow said support means to move under the weight of bulk material in said receptacle away from the receiving position while at the same time a subsequent receptacle moves into the receiving position.

4. An apparatus for continuously determining the variation in weight of fluent bulk material and more particularly, in detritus in drilling fluid discharged during a well drilling operation where drilling fluid discharged from the borehole is passed through a shale shaker to remove the detritus, said apparatus comprising: a plurality of receptacles; means supporting said receptacles for sequential movement to and through a detritus receiving position; measuring means operatively connected to measure the weight of detritus collected in a selected receptacle and for producing an output in response to said weight of detritus measured; and lock means operatively associated with said supporting means for maintaining a selected receptacle in said receiving position for receipt of detritus, said lock means being releasable when said weight in said selected receptacle reaches a predetermined weight to allow said support means to move under the weight of detritus in said receptacle away from the receiving position while at the same time a receptacle moves into the receiving position.

5. Apparatus as defined in claims 3 or 4, wherein in said means for measuring the weight is a load cell.

6. Apparatus as defined in claims 3 or 4, wherein said receptacle means is a thin concavely shaped aluminum plate.

7. Apparatus as defined in claims 3 or 4, wherein said lock means is an electromagnetic solenoid.

8. A method for continuously determining the variation in weight of fluent bulk material discharged during an industrial operation, said method comprising the steps of:

(a) moving a support means which supports a plurality of receptacles for sequential movement of said receptacles to and through a bulk material receiving position;

(b) measuring the weight of bulk material collected in the selected receptacle by a measuring means operatively connected thereto;

(c) maintaining said selected receptacle in said receiving position by a locking means operatively associated with said support means;

(d) releasing said locking means when said weight in said selected receptacle reaches a predetermined weight and allowing said support means to move under the weight of bulk material in said receptacle away from said receiving position, while at the same time allowing a subsequent receptacle to move into the receiving position; and

(e) continuously repeating steps (a) to (d).

9. A method for continuously deteraiining the variation in weight of fluent bulk material and more particularly, in detritus in a drilling fluid discharged during a well drilling operation; comprising the steps of:

(a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus;

(c) moving a support means which supports a plurality of receptacles for sequential movement of said receptacles to and through a detritus receiving position; (d) measuring the weight of detritus collected in the selected receptacle by a measuring means operatively connected thereto;

(e) maintaining said selected receptacle in said receiving position by a locking means operatively associated with said support means;

(f) releasing said locking means when said weight in said selected receptacle reaches a predetermined weight and allowing said support means to move under the weight of detritus in said receptacle away from said receiving position, while at the same time allowing a subsequent receptacle to move into the receiving position; and

(g) continuously repeating steps (a) to (f).

10. A method for continuously determining the variation in detritus in a drilhng fluid discharged during a well drilling operation; comprising the steps of:

(b) returning the drilhng fluid from which the detritus has been removed by the shale shaker to the well drilling operation;

(c) passing said detritus via a conveyor means over a weighing means connected to at least one load cell, whereby variations in weight of said conveyed detritus cause variations in stress on said at least one load cell; and

(d) continuously monitoring the variation in electrical output produced by said load cell(s) as a function of said variations in weight of the detritus.

11. A method for continuously determining the variation in detritus in a drilling fluid discharged during the drilling operation; comprising the steps of:

(a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus; said shale shaker including a spring mounted vibrating screen, at least one load cell being located beneath, and connected to a spring or springs on which said screen is mounted whereby variations in weight of said detritus passed over said screen cause a variation in stress on said load cell(s);

(b) returning the drilling fluid from which the detritus has been removed by the shale shaker to the well drilling operation; and (c) continuously monitoring the variation in electrical output produced by said load cell(s) as a function of said variations in weight of the detritus passed over said screen.

12. A method for continuously determining the variation in detritus in a drilling fluid discharged during a well drilhng operation; comprising the steps of:

(a) passing the drilling fluid discharged from the borehole through a shale shaker to remove the detritus; said shale shaker including a spring mounted vibrating screen beneath which are positioned a plurahty of means for measuring change in rate of velocity and said means for measuring being operatively connected to said vibrating screen;

^• (c) continuously monitoring the variation in the velocity of said vibrating screen as a function of variations of weight of the detritus passed over said screen.

13. A method for continuously determining the variation in detritus in a drilling fluid discharged during a well drilling operation; comprising the steps of:

(a) passing the drilhng fluid discharged from the borehole through a shale shaker to remove the detritus;

(c) passing said detritus to a trough means, said trough means including at least one load cell operatively connected thereto, whereby upon the weight of the detritus collected in said trough means reaching a predetermined limit as measured by said load cell, triggering a release means operatively connected to said trough for discharging said detritus from said trough;

(d) continuously monitoring the variation in electrical output produced by^' said load cells as a function of said variation in weight of the detritus; and

(e) continuously repeating steps (a) to (d).

14. An apparatus for continuously determining the variation in detritus in a drilling fluid discharged during a well drilling operation where drilling fluid discharged from the borehole is passed through a shale shaker to remove the detritus, said apparatus comprising: a trough means for receiving said detritus from said shaker; a load measuring means operatively connected to said trough means for producing an output indicative of the weight of detritus collected in said trough means; and release means operatively connected to said trough for discharging said detritus from said trough upon the weight of said detritus reaching a predetermined limit.

15. Apparatus as defined in claim 14, wherein in said load measuring means is a load cell.

16. Apparatus as defined in claim 14, wherein said trough means is pivotable between a receiving position and a discharge position.

17. apparatus as defined in claim 14, said load measuring means including an attachment means for selectively attaching said load measuring means to said trough means.

18. Apparatus as defined in claim 17, wherein said attachment means is an electromagnet.

19. An apparatus for continuously determining the variation in detritus in a drilling fluid discharged during a well drilling operation where drilling fluid discharged from the borehole is passed through a shale shaker to remove the detritus, said apparatus comprising: support means; trough means for receiving said detritus from said shaker, said trough means being pivotally supported on said support means; load cell attached to said support means; electromagπetic attachment means for selectively fixing said trough means to said load cell; release means having an input electrically connected to the output of said load cell means and having an output electrically connected to said electromagnet for de-energising said electromagnet when the weight of the detritus in said trough means reaches a predetermined limit; and recorder means electrically connected to the output of said load cell for continuously recording the variation in electrical output produced by said load cell as a function of said variation in weight of the detritus.