US3446986A - Flow indicator and control system - Google Patents

Description

May 27, 1969 1 cox FLOW INDICATOR AND CONTROL SYSTEM Filed Nov. 28, 1966 FIG. IA

FIG.

JOHN B. COX

INVENTOR.

BY ATTORNEY United States Patent US. Cl. 307-118 18 Claims This specification discloses a positive displacement type fluid flow indicator which comprises a chamber having inlet and outlet openings, a piston slidably disposed within the chamber, and means for producing a signal when the piston is displaced upwardly in the chamber in response to fluid flow through the indicator. The piston includes passageway means therein providing for fluid flow between the working and passive sides of the piston whereby accumulation of deposits within the chamber is alleviated. Also disclosed is a control system which generates a control function such as an alarm signal in response to the frequency of signals from a flow indicator falling outside of a specified range.

This is a continuation-in-part of application Ser. No. 410,975, filed Nov. 13, 1964, and now abandoned.

This invention relates to flow indicators and control systems for use in fluid distribution systems and more particularly fluid distribution systems associated with pumping oil wells.

It often becomes necessary during the life of an oil well to produce the well by artificial lifting means. This usually is accomplished by means of a reciprocating downhole pump which pumps the production fluid through a tubing string to the well head and thence through a gathering line to a header, tank, or other terminal point. The most commonly used reciprocating pump is the suckerrod type of pump in which the plunger of the downhole pump is reciproca'ted by a sucker-rod string extending through the production tubing to a prime mover at the surface.

In many cases, certain undesirable conditions occur while producing an oil well by a reciprocating pump. For example, if the well is pumped at a rate greater than that at which fluid enters the well from the formation, the well becomes dry or pumped off. Continued operation of the pump after the well becomes pumped off is obviously wasteful and, in addition, may cause extensive wear of the pump and producing equipment in the well. In addition to the possibility of becoming pumped off, the well may pump at an abnormally low rate, the production tubing or gathering line may fail, thus causing a leak, or the well may produce under conditions causing high water-oil or gas-oil ratios.

In accordance with the present invention, a control system is provided which is responsive to certain fluid characteristics in a distribution system characterized by pulsating fluid flow and which is particularly adapted to detect the presence of the undesirable conditions noted in the preceding paragraph in an oil well produced by means of a reciprocating pump. The fluids produced from a well by means of a reciprocating pump flow through the production string and gathering line in pulses or surges. The frequency of these surges at any designated point downstream of the pump varies not only with the frequency of the pump, but also with the incompressibility of the fluid. For example, if a well is produced at a high water-oil ratio, the production effluent will be relatively incompressible due to the high percentage of water therein and the frequency of the surges at the downstream point will approach the frequency at which the pump is reciprocating. However, if the water-oil ratio is within normal or acceptable limits, the production eflluent will exhibit a lesser degree of incompressibility and the frequency of the fluid surges at the designated point will be lower. Similarly, if the well is produced at a high gasoil ratio, the production eflluent will become relatively compressible and the frequency of the fluid surges will be still lower. Of course, should the well tend to pump off or should a leak occur in the tubing string or gathering line upstream of the control point, the frequency of the fluid surges will diminish toward the point where no fluid is flowing through the gathering line.

In the present invention, the pulsating nature of fluid flow through a conduit is used to advantage to indicate the compressibility of the fluid. The control system of the invention comprises a flow indicator means in the conduit which generates a biasing signal representative of the character of pulsating flow and therefore of the compressibility of the fluid in the conduit. In addition, a control means is provided which is responsive to the biasing signal and produces a control function when the signal falls outside of a specified range.

In a disclosed preferred embodiment of the invention, a flow indicator means located in a section of the gathering line of an oil well generates a signal each time a fluid surge passes through the section of the line and the control means is responsive to the frequency of these signals. If the signals occur at a frequency above a specified range, the control means generates a control function indicative of a high water-oil ratio. If the signals occur at a frequency below this range, the control means generates a control function which is indicative either of a high gas-oil ratio or a low flow rate, for example, due to the well pumping 01f or loss of fluid from the system through a leak.

In a further aspect of the invention, there is provided a new and improved flow indicator which is particularly well suited for use in combination in control systems of the type described above. This flow indicator comprises a chamber having an inlet opening which is adapted to be placed in fluid communication with a conduit such as the gathering line of an oil well. A piston is slidably disposed in the chamber and is adapted to be displaced, in response to fluid flow through the conduit, from a first position proximate with respect to the inlet opening to a second position which is remote with respect to this opening. The flow indicator also comprises means for generating a signal in response to movement of the piston to this second position. The piston includes passageway means which provide for the flow of fluid from the working side of the piston to the passive side thereof. Such fluid flow exercises a cleansing action on the walls of the chamber and tends to alleviate the accumulation of paraflin or other deposits within the chamber.

In a disclosed embodiment of the invention, the chamber and piston are formed of nonmagnetic and magnetic materials, respectively, and the signal generating means comprises a normally open magnetic switch. This switch is connected in a reset circuit which forms part of an electric control circuit. A timer in the control circuit operates to produce a control function upon the expiration of a specified time period. A reset clutch located in the reset circuit sets the timer back to a reference time each time the circuit is closed. The normally open magnetic switch in the reset circuit is mounted extcriorly of the piston-receiving cylinder such that it acts to close the reset circuit and thus energize the clutch each time the piston is displaced to the second position.

For a better understanding of the invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a view partially in section of 'a preferred form of flow indicator embodying the instant invention;

FIGURE 1A is a plan view of the piston in the flow indicator illustrating one form of passageway means;

FIGURE 1B is a plan view of such a piston showing another form of passageway means;

FIGURE 10 is a sectional view of such a piston showing yet another form of passageway means; and

FIGURE 2 is a schematic illustration of a preferred control circuit embodying the invention.

With reference to FIGURE 1, there is shown a flow indicator which functions to produce a signal pulse in response to a surge of fluid passing through a section of a conduit at which the flow indicator is located. The flow indicator comprises a T 2 which is shown as positioned in a conduit 3 such as the gathering line of an oil well. While only a short section of line 3 is shown, it will be understood that it may be connected at its upstream end to the well head of an oil well produced by means of a reciprocating pump and at its downstream end to a suitable terminal point. The T is made of plastic or other nonmagnetic material and preferably will be positioned adjacent the output end of the gathering line so that the pulsing mechanism will respond to leaks at any point in the gathering line. The T 2 comprises upper and lower legs 2a and 2b, respectively, which define a piston chamber and a lateral leg 20 which provides a fluid outlet from this chamber. The upper leg 2a of the T is closed to fluid flow with a cap 4 and forms a piston-receiving cylinder for the hereinafter described piston. The lower leg 2b is open to provide a fluid inlet to the chamber and this leg together with later-a1 leg 2c forms a section of the gathering line 3.

Slidably disposed within the chamber formed by legs 2a and 2b of the T is a piston 5 of steel or other magnetic material. The piston preferably is covered with a frictionreducing material such as Teflon, and is adapted to be displaced from a normal first position shown at which it is intermedial of the inlet and outlet openings of the chamber to a second position in leg 2a at which it is extrarnedial of these openings.

The flow indicator further comprises means for generating a signal in response to movement of the piston 5 to this second position. In the preferred embodiment shown this signal generating means takes the form of a magnetically operated switch 6 which carries a member 8 formed of magnetic material and which normally is biased by a leaf spring 7 to the open position. Switch 6 is in an enclosure 9 formed on the exterior of the chamber formedby legs 2a and 2b. The enclosure is provided with a removable plate 9a in order to provide for access to the switch. Either piston 5 or member 8 is magnetized. Each time a surge of fluid is delivered through the gathering line, piston 5 is moved upwardly at least to the extent necessary to allow fluid to flow from leg 2b to leg 20 and the action of the magnet causes the switch 6 to close. After the fluid surge passes through the pulsing mechanism, the piston returns under the influence of gravity to the position shown where it rests on a shoulder 10.

From an examination of FIGURE 1, it will be recognized that an accumulation of paraflin or other solid or semisolid deposits on the passive face of the piston 5 or on the walls of the upper portion of the piston chamber could seriously hamper the operation of the flow indicator and ultimately cause a stoppage. In a preferred embodiment of the invention, the accumulation of such deposits is prevented or at least significantly retarded through the provision of passageway means in the piston 5 which provides for the flow of fluid from the working side of the piston to the passive side thereof. The modifiers working and passive are used herein and in the appended claims in a conventional sense with reference to the primary movement of the piston under the influence of a fluid surge passing through the flow indicator. Thus, the working side of the piston is the zone of the chamber within which fluid force is applied to move the piston to the aforementioned second position. Similarly, the working face of the piston 5 shown in FIGURE 1 is the lower face against which the fluid acts to move the piston upwardly and the passive face is, of course, the upper face of the piston.

Preferably, the passageway means takes the form of a plurality of channels which terminate separately in the passive face of the piston in order to provide for a wide distribution of fluid flow. More particularly and with reference to FIGURE 1A, there is shown a top plan view of piston 5 in which such passageway means comprises a plurality of flow channels 5a which extend longitudinally through the piston. As can be seen from an examination of FIGURE 1A, the channels 5a terminate in the passive face of the piston 5 at locations eccentric of the longitudinal axis of the piston and adjacent the outer periphery thereof. Thus, fluid issuing from the flow channels will travel along the wall of that portion of the chamber generally defined by leg 2a and tend to keep this wall clear of parafiin or other deposits.

In accordance with another embodiment of the invention, illustrated in FIGURE 1B, the passageway means comprises a plurality of open channels for-med in the outer periphery of the piston. More particularly and with reference to FIGURE 1B, there is shown a piston 50 provided with a plurality of longitudinal slots or open channels 5d in the outer wall thereof. The arrangement of the channels 5d ensures that the fluid passing through these channels from the working side to the passive side of the piston directly and effectively contacts the wall of the piston chamber. In addition, the structure shown in FIGURE 1B reduces the surface area of the piston in contact with the wall of the piston chamber and thus the resistance due to friction to movement of the piston.

Turning now to FIGURE 1C, there is illustrated another embodiment of the invention in which the passageway means comprises one or more deviated channels which extend from the side wall of a reduced lower portion of a piston to the passive face of the piston. In FIGURE 1C there is shown in longitudinal section a piston 51 which has a lower portion 5g of reduced diameter which defines an annular shoulder 5h. It will be recognized that shoulder Sit and the bottom surface 5 of the piston form a compound working face against which fluid flowing through the conduit acts to displace the piston from the first to the second position. The piston 51 is provided with deviated channels as indicated by reference numeral 5k which extend inwardly from the surface of reduced portion 5g and thence upwardly where they terminate in the passive face of the piston 51.

The embodiment of FIGURE 1C is of particular advantage where it is desired to reduce the rate of flow through the channels without decreasing the number of channels or reducing their cross-sectional areas to such an extent that they might become easily blocked by paraffin or other material in the oil stream. In this regard, it will be recognized that the change in direction provided by the deviation in the channels will decrease the flow rate for a given pressure gradient across the piston.

It is to be recognized that various combinations of the passageway systems shown in FIGURES 1A, 1B, and 10 may be utilized. For example, the piston 50 shown in FIGURE 1B may be provided with a central internal channel or with a plurality of internal channels spaced similarly as those shown in FIGURE 1A.

Turning now to FIGURE 2, there is shown a preferred control circuit embodying the invention. The switch 6 of the flow indicator is connected in the circuit by means of leads 6a and 6b (FIGURE 1). The control circuit includes means for producing automatically a control func tion such as the energization of an alarm beacon in response to the frequency of the signal pulses falling outside of a predetermined range which is representative of acceptable gas-oil and water-oil ratios.

More particularly, and as shown in FIGURE 2, the control circuit includes a primary timer 11 which acts to produce a control function in response to a low pulse frequency and a secondary timer 12 which acts, in conjunction with the primary timer, to produce a control function in response to a high pulse frequency. Primary timer 11 includes a cam 11a which is driven by a motor 11b and rotates in a clockwise direction to sequentially close contacts 11c and 11d. Cam 11a is shown in the start position in which a further contact He is closed. The active surface of the cam will hold contact 112 closed until after contact 11d is closed. Secondary timer 12 includes a cam 12a which is driven by a motor 12b in a clockwise direction to close contact 120. The timer also includes a contact 12d. Cam 12a holds contact 12d closed until after contact 12c is closed. Timers 11 and 12 also include primary and secondary reset clutches 11 and 12e, respectively, which act to reset their respective timers to the start positions when the clutches are energized. The reset circuit for clutch 122 can be traced through contact 12d, conductor 14, and contact 11c, and the reset circuit for clutch 11 can be traced through contact 11c, conductor 15, and switch 6.

The individual components of the control circuit may be conventional items. For example, suitable primary and secondary timers including the reset clutches are commercially available from Eagle Signal Company, Moline, 111. as Model No. HP501, Off Delay.

The control system operates as follows. The control circuit is energized by closing a switch 16 which connects the circuit across a voltage source E. Immediately upon closure of switch 16, the motor 11b of timer 11 is energized through contact 112. Cam 11a is driven by the motor and immediately begins to rotate in a clockwise direction. The rotational movement of the cam continues until reset clutch 11 is energized by the closing of switch 6 in the pulsing mechanism. The reset clutch then acts to return the timer cam 11a back to a reference time, e.g., the zero time or start position shown.

The above sequence of operations will be repeated as long as the gas-oil ratio stays below an acceptable limit and the well produces above a preselected minimum rate as determined by the time interval set into timer 11. However, should the gas-oil ratio rise above the acceptable value, or should the flow rate fall below the minimum because of a leak or for any reason regardless of the gas-oil ratio, the pulsing mechanism will fail to close switch 6 within the time period required for cam 11a to close contact 11d in the circuit of a relay 18. When contact 11d is closed, relay 18 picks up and closes its contact 18a, thus completing a circuit to an alarm beacon 20. Beacon 20 may be merely a lamp or alarm hell, or it may include a telemetering system for sending a signal to a central headquarters by radio, tele phone, etc. Immediately after contact 11d is closed, the continued rotation of the cam will cause contact 112 to open, thus breaking the circuit to the motor and clutch of the timer. The timer cannot thereafter be activated until the reset button 21 is closed. This of course acts to energize the reset clutch which returns the timer cam to the position shown.

The operation of timer 12 is as follows. The reset clutch 12e is energized through the contact 110 of timer 11. During normal operation, when the frequency of signal pulses from the pulsing mechanism is within the normal operating range, contact 110 will be closed periodically by cam 11a, thus energizing reset clutch 12e which acts to return cam 12a to the position shown. However, should the water-oil ratio increase to above the acceptable limit, the frequency of pulses will increase 6 so that reset clutch 11 will be energized and the timer reset to the position shown before the cam has rotated a suflicient amount to close contact 110. Reset clutch He therefore will not be energized within the time limit set into timer 12, and cam 12a will continue its rotational movement to close contact 12c. This completes a circuit through a relay 25 which picks up and closes its contact 25a, thus energizing the alarm beacon 20. Immediately after contact 12c is closed, contact 12d is opened, thus breaking the circuit through motor 12b and clutch 12c and preventing further movement of the cam. The timer will not thereafter operate until it is reset by pushing button 21, thus energizing clutch 126 to return the cam to the position shown.

In the disclosed embodiment, timers 11 and 12 both produce the same control function, i.e., the energization of beacon 20. However, it will be recognized that each timer may operate to produce a separate control function. For example, beacon 20 could be taken out of series with contact 25a so that it responds only to the closing of contact 18a, and a second beacon provided in series with contact 25a, but in parallel with contact 18a. Also, the control function produced by the primary and/ or secondary timer may act to stop or otherwise adjust the action of the well pump.

Having described a specific embodiment of the instant invention, it will be understood that further modifications thereof may be suggested to those skilled in the art, and it is intended to cover all such modifications as fall with in the scope of the appended claims.

I claim:

1. A flow indicator comprising: means forming a chamber having an inlet opening therein and a lateral outlet opening spaced from said inlet opening, a piston slidably disposed in said chamber and adapted to be displaced from a first position intermedial of said inlet and outlet openings to a second position extramedial of said inlet and outlet openings, means for generating a signal in response to said piston being displaced from said first position to said second position, and passageway means in said piston providing :for fluid communication between the working side of said piston and the passive side of said piston.

2. A flow indicator comprising: means forming a chamber having an inlet opening therein, a piston slidably disposed in said chamber and adapted to be displaced from a first position proximate with respect to said inlet opening to a second position remote with respect to said inlet opening, passageway means in said piston providing for fluid flow between the working side of said piston and the passive side of said piston, and means for generating a signal in response to said piston being displaced from said first position to said second position.

3. The flow indicator of claim 2 wherein said passageway means comprises a plurality of channels.

4. The flow indicator of claim 2 wherein said passageway means comprises a plurality of channels terminating in the passive face of said piston at eccentric locations adjacent but spaced inwardly from the outer periphery of said piston.

5. The flow indicator of claim 2 wherein said passageway means comprises a plurality of open channels formed in the outer periphery of said piston.

6. The flow indicator of claim 2 wherein said piston has a reduced lower portion and wherein said passageway means comprises a deviated channel extending from the periphery of said reduced portion of said piston to the passive face of said piston.

7. The flow indicator of claim 6 comprising a plurality of said deviated channels, said channels terminating in the passive face of said piston at eccentric locations adjacent but spaced inwardly from the outer periphery of said piston.

8. In a control system for a fluid distribution system having a fluid carrying conduit, flow indicator means in said conduit for generating a biasing signal comprised of time-spaced pulses whose frequency is inversely proportional to the compressibility of the fluid in said conduit whereby said signal is representative of the compressibility of the fluid in said conduit, and control means responsive to the frequency of said pulses falling outside of the upper and lower limits of a specified frequency range for producing a control function.

9. In a control system for a fluid distribution system having a conduit and means in fluid communication with said conduit for causing pulsating fluid flow through said conduit, flow indicator means at a section of said conduit for generating a signal in response to a surge of fluid flowing through said section whereby the signal output from said flow indicator means is comprised of timespaced pulses under conditions of pulsating fluid flow, and control means responsive to the frequency of said pulses falling outside of the upper and lower limits of a specified frequency range for generating a control function.

10. The system of claim 9 wherein said control means comprises a control circuit including a first timing circuit for producing a control function in response to a signal pulse frequency below the ower limit of said frequency range and a second timing circuit for producing a control function in response to a signal pulse frequency above the upper limit of said specified frequency range.

11. The control system of claim 9 wherein said flow indicator means comprises means forming a chamber having an inlet opening in fluid communication with said conduit, a piston slidably disposed in said chamber and adapted to be displaced from a first position proximate with respect to said inlet opening to a second position remote with respect to said inlet opening in response to fluid flow through said conduit, and signal means for generating a signal each time said piston is displaced from said first position to said second position.

12. The control system of claim 11 further comprising passageway means in said piston providing for fluid flow from the working side of said piston to the passive side of said piston.

13. The control system of claim 11 wherein said chamber and said piston are formed of nonmagnetic material and magnetic material, respectively, and said control means comprises a control circuit including normally open first and second reset circuits, primary timing means in said control circuit for closing said normally open second reset circuit upon the expiration of a first specified time period and for producing a control function upon the expiration of a second specified time period, secondary timing means in said control circuit for producing a control function upon the expiration of a specified time period, said last-named time period being greater than the first time period for said primary timer, primary reset means in said first reset circuit for resetting said primary timing means to a reference time when said first reset circuit is closed, secondary reset means in said second reset circuit for resetting said secondary timing means to a reference time when said second reset circuit is closed, and said signal means comprising a normally open magnetic switch mounted exteriorly of said chamber adjacent said second position and connected in said primary reset circuit for closing said primary reset circuit in response to the displacement of said piston from said first position to said second position.

14. In a control system for a fluid distribution system having a conduit and means in fluid communication with said conduit for causing pulsating fluid flow through said conduit, means forming a chamber having an inlet opening in fluid communication with said conduit, a piston slidably disposed in said chamber and adapted to be displaced from a first position proximate with respect to said inlet opening to a second position remote with respect to said inlet opening in response to fluid flow through said conduit, a control circuit including a normally open reset circuit, timing means in said control circuit for producing a control function upon the expiration of a specified time, reset means in said reset circuit for resetting said timer to a reference time when said reset circuit is closed, and a normally open switch mounted exteriorly of said chamber and connected in said reset circuit for closing said reset circuit in response to the displacement of said piston from said first position to said second position.

15. The control system of claim 14 further comprising passageway means in said piston providing for fluid flow from the working side of said piston to the passive side of said piston.

16. A flow indicator comprising means forming a chamber having an inlet opening therein and a lateral outlet opening spaced from said inlet opening, a piston slidably disposed in said chamber and adapted to be displaced from a first position intermediate of said inlet and outlet openings to a second position extramedial of said inlet and outlet openings; passageway means in said piston providing for fluid communication between the passive side of said piston and said outlet opening when said piston is in said second position, and means for generating a signal in response to said piston being displaced from said first position to said second position.

17. The flow indicator of claim 16 wherein said passageway means comprises at least one channel extending from the passive face of said piston and terminating in the side of said piston.

18. In a control system for a well installation having a conduit and a reciprocating downhole pump for delivering oil from said well through said conduit, flow indicator means in said conduit for generating a biasing signal comprised of time-spaced pulses whose frequency is directly proportional to the amount of water in said oil and inversely proportional to the amount of gas in said oil whereby said signal is representative of the amount of gas and water in said oil, and control means responsive to the frequency of said pulses falling outside of a specified range for generating a control function.

References Cited UNITED STATES PATENTS 2,628,297 2/1953 Grauer ZOO-84.3 2,791,657 5/1957 Bloxsom et a1 200-84.3 2,927,175 3/1960 Booth et al. ZOO-84.3 2,406,099 8/1946 Penick 137246.13 X 2,419,942 5/ 1947 Brewer.

2,433,208 12/1947 Evans 137238 2,853,575 9/1958 Reynolds ZOO-81.9 3,057,977 10/1962 Caswell 340239 X 3,247,499 4/1966 Dumpleton et al. 340239 ROBERT K. SCHAEFER, Primary Examiner.

T. B. JOIKE, Assistant Examiner.

US. Cl. X.R.

73-208, 224; ZOO- 81.9, 82; 340239

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