US2838008A - Automatic well rocking and kick-off apparatus and process - Google Patents

Description

June 10, 1958 8 R. G. VNISLE ET AL 2,838,008

AUTOMATIC WELL ROCKING AND KICK-OFF APPARATUS AND PROCESS Filed April 13, 1953 3 Sheets-Sheet l INVENTORS F. H. POETTMANN R. G. NISLE BY 21% i/Z ATTORNEYS June 10, 1958 AUTOMATIC WELL R. G. NISLE ET AL 2,838,008

Filed April 13, 1953 FIG. 2

INVENTORS J F. H.POETTMANN ATTORNEYS AUTOMATIC WELL ROCKENG AND KICK-DEF APPARATUS AND PROCESS Robert G. Nisle and Fred 0kla., assignors to Phillips poration of Delaware Application April 13, 1953, Serial No. 348,546 9 Claims. (Cl. 103-232) H. Poettmann, Bartiesville, Petroleum Company, a corand outside thereof, the rise of the liquid inside of the n tubing eventually becomes great enough to lower the level of the liquid on the outside of the tubing to the level of the end of the tubing, or to the level of a gas injection valve in the tubing, so that the pressurizing gas is forced up the tubing, thereby atomizing the oil therein and forming a froth or emulsion which greatly decreases the weight of the hydrostatic head inside the tubing so that the pres surizing gas eventually raises the froth or emulsion inside the tubing to the well head where it can be drawn otf in continuous flow.

The rate at which the pressure must be switched from tubing to annulus and back to the tubing depends upon well factors which are notknown; however, it should be obvious that reversing the gas pressure from the well tubing to the well casing and vice versa should be effected at the instant at which the fluid in the tubing reaches its maximum height in any particular cycle of operation and also when the fluid in the annulus (casing outside of the tubing) reaches its maximum height at the opposite phase of the cycle. It is particularly diflicult to hand-operate the valves which control the flow of pressurizing gas into the casing and tubing of the well and also the flow of fluid from the well, once the flow has reached the well head.

The principal object of the invention is to provide an apparatus and process for automatically rocking a gas lift well. Another objectof the invention is to provide means and method for automatically reversing the How of pressurizing gas into and out of the well tubing and casing at the moment the fluid in the well reaches the maximum and minimum levels. A further object of the invention is to provide means and method of synchronizing the flow of pressurizing gas into and out of the well with fluid flow out of the tubing from the well head. It is also an object of the invention to provide a method and apparatus for terminating the rocking of a gas lift well when flow of liquid in the tubing has reached the efiluent line or production string and automatically applying the pressurizing gas solely to the annulus of the well. Other objects of the invention will become apparent from a consideration of the accompanying disclosure.

The invention utilizes the fact that gas will flow into or out of the tubing or the annulus surrounding the tubing of a well so long as the liquid is in motion therein. When the highest point of liquid flow in any cycle is reached, the gas ceases to flow for an instant and then reverses its direction of flow. This is the instant or point at ates atent 2 which reversal should take place. The invention therefore utilizes the instant of zero rate of gas flow in the conduit or line leading to either the tubing or the annulus, as measured or indicated by difierential pressure across an orifice or choke, to reverse the flow of gas to and from the tubing and the annulus.

The invention provides two embodiments of the rocking apparatus and process. In automatically rocking a well and in terminating the rocking and instituting continuous flow, the invention utilizes three functional elements, (1) a flow rate sensing device, (2) a reversing valve, and (3) a cut-off system. One embodiment of the flow rate sensing device comprises a manometer in combination with an orifice or choke arranged so that the liquid level in the arms of the manometer indicates a pressure differential across the orifice and is uniform in both arms when there is no dilferential pressure across the orifice, thereby indicating zero gas flow rate in the conduit in which it is installed. A suitable light source or beam is focused on a photo-electric cell or other light sensitive tube so that the beam of light passes through the manometer arms just above the liquid level when the liquid stands at the same level in both arms and is cut off by the opaque liquid in either one of the arms when gas is flowing thru the orifice or choke. With this arrangement of apparatus, an electrical impulse or signal is set up in a suitable circuit at the instant the gas flow rate in the conduit is zero. This electrical impulse is amplified and utilized to operate a reversible motor or other equivalent device which in turn operates a reversible 4-way valve so as to change the direction of flow of pressun'zing gas into and out of the tubing and annulus.

Another modification of the flow rate sensing device utilized in the invention comprises a commercially available differential pressure gage which sends out electrical impulses at any predetermined differential pressure values, such as zero in'the instant application. The arms of the gage are in communication with the conduit in which the gas is flowing on opposite sides of an orifice or choke therein. The electrical impulses which are initiated when the flowrate is zero are amplified and utilized to reverse the 4-way reversing valve in the same manner as set forth relative to the manometer type sensing device. It should be understood that any suitable flow sensing device which operates to initiate an electrical signal or impulse When the flow rate or pressure difierential across an orifice in a gas line reaches zero can be utilized in the invention and is incorporated therein.

The reversing valve may be any suitable commercially availableelectrically operated 4-way valve. Two different types are hereinafter described, one requiring a single impulse to throw it from one position to another while the other is operated by two solenoids acting in opposite directions.

The purpose of the cut-oif system is to terminate the operation of the rocking mechanism when the well starts flowing. The invention provides two modifications of the cut-off system, one comprising a water hammer tube having a diaphragm which operates a switch thereby setting up an electrical impulse which is amplified and the amplified impulse operates a pair of quick-acting valves thereby shutting off flow of pressurizing gas to and from the tubing and opening the effluent line or producing string to the flow of liquid. This leaves the 4-way valve in the position which feeds pressurizing gas continually into the annulus and thereby keeps the well on flow.

The other cut-olf system is combined with the commercial gage utilized in sensing fluid flow in the conduit connected with the well tubing and in sending out electrical impulses. It'comprises a diaphragm and an associated electrical circuit utilizing a Wheatstone bridge to set up electrical impulses which are translated into signals which actuate the electrically operated quick-acting valves controlling flow of pressurizing gas into and from the tubing and liquid flow out of the well head.

A more complete understanding of the invention may be had by referring to the accompanying drawing of which Figure l is a diagrammatic illustration of one arrangement of apparatus for automatically rocking a well and cutting off the rocking when liquid in the tubing reaches the efiluent line; Figure 2 is a circuit diagram of the flow sensing device and reversing mechanism of the apparatus of Figure 1; Figure 3 is a detailed showing partly in section of the water hammer tube of Figure l and the wiring diagram utilized to operate the quickacting valves for terminating the rocking and continuing flow of the well; Figure 4 is a diagrammatic showing of a second modification of apparatus for automatically rocking a well and terminating the rocking to initiate continuous flow of the well; and Figure 5 is a wiring diagram of the flow sensing device and circuit utilized to operate the reversing valve and the quick-acting valves of Figure 4.

Figure 1 shows one arrangement of apparatus for automatically rocking an oil well to initiate flow and to keep it flowing once flow has been initiated. Gas used to rock the well passes through conduit 17 and reversing valve 15 to either of two conduits 13 or 14. In the arrangement shown, gas is being applied to annular space 12 between casing and tubing 11 causing fluid to be lifted inside of tubing 11. During the phase of the rocking cycle shown, gas is flowing through 17, reversing valve 15, conduit 13, orifice or choke 20, and into space 12. Exhaust gas from the well is flowing from tubing 11 to line 14, thru valve 52, and via reversing valve 15 to exhaust conduit 16. Gas continues to flow and lift the oil in the tubing until the weight of the column of the fluid in the tubing equals the force being applied by the gas. At this instance the pressures on either side of orifice become equal and the levels of the mercury in both columns in the manometer 21 are at the same height, allowing light to pass from source 22 to photocell 23. The pulse produced when light strikes 23 is amplified by amplifier 24, rectified by rectifier 26, and applied to relay control box 27. Relay control box 27 permits properly phased voltages to be applied to reversible servomotor 28 via leads 25, 31, and 33. Amplier 24 and relay control box 27 are grounded. Servomotor 28 operates through a mechanical linkage -19 to move crank arm 18 of reversing valve 15 to such a position that the'gas flowing through conduit 17 now flows through conduit 14 and valve 52 into tubing 11 and-the gas in annulus 12 flows thru conduit 13, orifice'Zt), reversing valve 15, and out exhaust conduit 16. Pressure exerted by the gas in tubing 11 forces liquid in the tubing downwardly and liquid in annulus 12 upwardly until the differences in the weights of the columns of liquid equals the force applied by the gas in the tubing. At this time the pressure across orifice 20 becomes zero, allowing light from source 22 to pass through the arms of manometer 21 so as to reverse valve 15 and again introduce gas into annular space 12 and force liquid up tubing 11, thereby causing a rocking of liquid in the two columns.

This rocking process continues automatically until the liquid in the annulus is lowered to theend of the tubing or to a gas injection valve therein and air enters the tubing so as to atomize the oil and form a froth therein. The density of the froth is low, which facilitates the eventual flowing of the same thru the tubing into discharge line or production string 56.

It will be apparent that'during the rocking processvalve 54 has been kept closed and valve 52 kept open. When the fluid flows into conduit 58, the fluid pressure acts against the lower side of diaphragm switch 60, closing an electric circuit which operates to open valve 54and close valve 52. The detail electric circuits of the schematics shown in Figure 1 are shown in Figures '2 and 3.

Figure 2 shows the detail circuit for automatically rocking the well while Figure 3 shows the detail circuit for opening valve 54 and closing valve 52. It will be apparent from Figure 1 that, once the well starts to flow, the differential gas pressure across orifice 28 is sufiicient that the mercury in the arms of the manometer will always be unequal, thus avoiding interrupting of the flow process. in Figure 2 the mercury in the arms of the manometer tube are shown with one arm higher than the other, that is. the pressure on one arm is greater than on the other. Under this condition no signal is received by photocell 23. When the mercury in the two arms of 21 stand at the same level, a beam of light passes from source 22 to photocell 23. This pulse signal is amplified by amplifier 24, rectified by rectifier 26, and filtered to provide a direct current pulse by filter 28. With the solenoids in the position shown in control box 27, the electric pulse is applied to junction 34, armature core 32, spring contact switch 29, lead 37, and solenoid 35 to ground. Solenoid 35 pulls armature 41 to the right, opening spring contact switch 29 and closing spring contact switch 4i) in preparation for the next cycle of operation. Armature 41 pulls transformer core 39 to the right thus coupling the 60 cycle alternating current into the circuit containing leads 25, 31, and 33 to servomotor 28 to cause the motor to rotate in, say, a clockwise direction and move crank arm 18 of reversing valve 15 thru so as to cause a reversal of gas flowing to the well. Motor control box 44 is mounted on motor 28. Numerals 46 and 48 designate the coils of servomotor 28. The motor control system for motor 28 is basically that shown on page 65 of the book entitled Principles and Methods of Telemetering by Perry A. Borden et al., Reinhold Publishing Corporation, New York City, New York (1948).

It will be apparent from Figure 2 that the armatures of relay box 27 remain in one position or may be held in one position by a center mounted compression spring (not shown) until the next electric pulse is applied to junction 34. The next pulse will be applied to junction 34 when the mercury in the two columns of manometer 21 again stands at the same level and the light signal strikes photocell 23. When the second pulse arrives at junction 34, current flows through transformer core 39, armature 41, spring contact switch 40, lead 42, and solenoid coil 43 to ground. This pulse pulls armature 32, core 39, and armature 41 to the position'shown in Figure 2 thus changing the coupling in the alternating circuit causing servomotor 28 to reverse valve 15 and thus reverse the flow of gas in the conduits leading to the well. This repeated reversal of the flow and attendant up and down movement of liquid in tubing 11 and annulus 12 is termed rocking.

Referring to Figure 3, rocking continues until fluid enters conduit 58, causing diaphragm 62 to be deflected bringing together contacts 64. Contacts 64 connect an electric circuit thru battery 72, diaphragm 62, lead 70, and resistance 74, applying a positive potential to the grid of vacuum tube 76 thereby permitting it to conduct.

When vacuum tube 76 conducts, current flows from battery 82 thru relay coil 80, thru vacuum tube 76 and lead 78 to ground. When tube 76 conducts, it actuates relay switch 84 by means of coil 80, and switch 84 then applies current from battery 86 thru lead 88 to solenoids 90 and 92 which operate valves 52 and 54. Relay switch 84 is held closed by a suitable latching mechanism (not shown), once it becomes closed. It should be noted that valve 54 is opened at the time valve 52 is closed by this electric circuit.

Figure 4 is an embodiment of the present invention in which the mercury manometer 21 of Figure 1 is replaced with a commercially available differential pressure gage such as the electric pressure strain gage described in Patent No. 2,455,883 (1948) by L. D. Statham. Numeral 20 designates an orifice which is bypassed by conduit 102, diiferential pressure gage .and'conduit 101. A diiferential pressure measurement from the differential pressure gage 100 is transmitted over leads 105 and 106 to relay control box 108. In the present embodiment the difierential pressure gage 100 operates to detect differential pressure measurements and their direction. At the stage of operation shown in Figure 4, the liquid in tubing 11 is below that of the oil in the annulus 12 between casing and tubing 11. Under this condition gas entering conduit 17, passes through reversing valve 15, conduit 14, valve 52, and orifice 20 into tubing 11. Gas continues to flow in this direction until the pressure differential across the orifice or choke 20 approaches zero, at which time gage 100 operates through relay control box 108 and solenoid control 116 to operate reversing valve 15 so as to cause the pressurizing gas to flow from conduit 17 thru reversing valve 15 and conduit 13 into annulus 12. At the same time the gas from tubing 11 is exhausted thru con duit 14, containing orifice 20 and valve 52, thru reversing valve 15, and exhaust conduit 16. Valves 52 and 54 are operated by solenoid 120 whenever the pressure across the differential pressure gage 100 becomes extreme due to oil entering the orifice or choke 20, as will be apparent from the circuit of Figure 5. Numerals 109 and 121 designate brackets for holding control box 108 and solenoid 120.

Figure 5 shows the bridge arrangement of the differential pressure gage 100 which is similar to that shown in Figure 13 of the above mentioned patent to L. D. St-atham. Electrical leads 103 and 104 are connected to battery 115 which supplies a source potential. Electric leads 105 and 106 carry two unbalanced signals from the pressure gage 100 to an amplifier 117. The output of amplifier 117 operates a two-position polarized relay switch 124. When the armature 125 of relay 124 is in its upper position, current flows from battery 136 to armature 125, lead 134, solenoid coil 139 and back to battery 136 causing armatures 138 and 140 to be moved towards the left position as shown in Figure 5. The reversing valve 15 in the position as shown in Figure 5 is for a differential pressure in the opposite direction to that which is described in Figure 4. Armature 125, when made to move to its lower position by a reversal in the pressure differential on gage 100 causes current to flow from battery 136, armature 125, lead 132, solenoid coil 141 and back to battery 136. This causes armatures 140 and 138 to move to the right, reversing valve 15 so as to reverse the flow of gas to the well.

When the differential pressure gage 100 becomes extremely unbalanced as caused by a surge of oil into its chamber or across orifice 20, considerable amount of current is made to flow in the polarized relay in the sense in which it operates and also through resistance 126 and relay coil 130. Relay coil 130 then operates switch 131 closing an electrical circuit from battery 132, solenoid 120, and back to battery 132. Solenoid coil 120 actuates valves 54 and 52 opening the former and closing the latter so that oil will flow out through valve 54 and fiow of gas to the tubing will cease. It will be apparent that as long as extreme pressure is applied to the differential pressure gage that valve 54 will be closed and valve 52 will be open. Switch 131 may be held closed by a suitable latching mechanism not shown.

The sensing device, such as the orifice and manometer and differential pressure gage, may be mounted in the conduit leading to the space between the casing and tubing, as shown in Figure 1, or in the conduit leading to the tubing, as shown in Figure 4. The cut-off system for stopping the rocking process and starting the oil flow at the surface may be separate from the rocking system, as shown in Figure 1, or it may be incorporated as part of the rocking system, as shown in Figure 4.

Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

We claim:

1. Apparatus for rocking a gas lift well to initiate flow, comprising in combination, a well having a tubing and a casing; a pair of conduits, one communicating with the tubing and the other with the casing of said well; a gas pressure supply line adapted to feed pressurizing gas alternately into said conduits thru the hereinafter defined control valve; a control valve intermediate said supply line and said pair of conduits and in communication therewith; control means in said valve for directing the flow of gas from said gas pressure supply line alternately to said conduits and simultaneously exhausting gas from the other of said conduits in each instance; an orifice in one of said. conduits; a differential-pressure-sensitive device in communication with the conduit each side of said orifice including means for sending out electrical impulses in response to a predetermined pressure-differential across said orifice; electrically operated reversing means on said control means; and amplifying means in circuit with said electrically operated reversing means and actuatable by said differential-pressure-sensitive device.

2. Apparatus for rocking a'gas lift well to initiate How and automatically terminating the rocking when flow is started, comprising in combination, a pair of conduits, one adapted to connect with the tubing and the other with the casing of a well; a gas pressure supply line adapted to feed pressurizing gas alternately into said conduits thru the hereinafter defined control valve; a control valve intermediate said supply line and said pair of conduits and in communication therewith; control means in said valve for directing the flow of gas from said gas pressure supply line alternately to said conduits and simultaneously ex hausting gas from the other of said conduits in each instance; an orifice in one of said conduits; a differentialpressure-sensitive device in communication with the conduit each side of said orifice including means for sending out electrical impulses in response to a predetermined pressure-diiferential across said orifice; electrically oper-" ated reversing means on said control means; amplifying means in circuit with said electrically operated reversing means and actuatable by said differential-pressure-sensitive device; a pressure-sensitive device in communication with a line connected to the upper end of said tubing including means for sending out electrical impulses when liquid flows into said last-named line; at producing string in communication with the upper end of said tubing; a pair of quick-acting valves, 21 first one ins'aid producing string and a second one in the conduit communicating with said tubing; electrical operating means for opening the first and closing the second of said valves; and amplifying means in circuit with said pressure-sensitive device and with said electrical operating means.

3. Apparatus for rocking a gas lift well to initiate flow, comprising in combination, a pair of conduits, one adapted to connect with the tubing and the other with the casing of a well; a gas pressure supply line adapted to feed pressurizing gas alternately into said conduit thru the hereinafter defined control valve; a control valve intermediate said supply line and said pair of conduits and in communication therewith; control means in said valve for directing the flow of gas from said gas pressure supply line alternately to said conduits and simultaneously exhausting gas from the other of said conduits in each instance; flowsensing means in one of said conduits for sensing fiuid flow rate therein and sending out electrical impulses at a predetermined fluid flow rate; electrically operated reversing means on said control means; and amplifying means in circuit with said electrically operated reversing means and actuatable by said flow-sensing means.

4. Apparatus for rocking a gas lift well to initiate flow and automatically terminating the rocking when flow is started, comprising in combination, a well having a tubing and a casing; a pair of conduits, one communicating with the tubing and the other with the casing of said well; a gas pressure supply line adapted to feed pressurizing gas alternately into said conduits thru the hereinafter defined control valve; a control valve intermediate said supply line and said pair of conduits and in communication therewith; control means in said valve for directing the flow of gas from said gas pressure supply line alternately to said conduits and simultaneously exhausting gas from the other of said conduits in each instance; flowsensing means in one of said conduits for sensing fluid flow rate therein and sending out electrical impulses at a predetermined fluid flow rate; electrically operated re versing means on said control means; amplifying means sensitive to said flow-sensing means in circuit with said electrically operated reversing means; a pressure-sensitive device in communication with a line connected to the upper end of said tubing including means for sending out electrical impulses when liquid flows into said last-named line; a producing string in communication With the upper end of said tubing; a pair of quick-acting valves, a first one in said producing string and a second one in the conduit communicating with said tubing; electrical operating means for opening the first and closing the second of said valves; and amplifying means in circuit with said pressure-sensitive device and with said electrical operating means.

5. The apparatus of claim 1 in which said differentialpressure-sensitive device comprises a mercury manometer having arms connected with the conduit each side of said orifice, a light-sensitive cell, and a light source focused on said cell, both disposed in relation to said manu ometer so that the line of sight from said source to said cell passes thru the arms of said manometer just above 8 the liquid level therein when the pressure difierential is zero.

6. The apparatus of claim 1 in which said differentialpressure-sensitive device comprises a difierential-pressure strain gage.

7. Apparatus for terminating the rocking of a gas lift well and initiating continuous flow of the well, which comprises a conduit adapted to connect to a Well head; a pressure-sensitive device connected to said conduit; electrical means in actuable connection with said device for sending out electrical impulses when liquid flows into said conduit; a first quick-acting valve having electrical operating means for opening same on a given electrical impulse from said electrical means, aforesaid valve being adapted for insertion in a conduit carrying a production stream from said well head; a second quick-acting valve having electrical operating means for closing same on a given impulse from said electrical means, aforesaid valve being adapted for insertion in a pressuriZing-gas supply line adapted to connect to said well head; and an amplifier and current source in operative circuit with said device and with the operating means of said valves.

8. The apparatus of claim 7 in Which said device comprises a flexible diaphragm in combination with an electrical switch which completes said circuit when fluid pressure is applied to said diaphragm.

9. The apparatus of claim 7 in which said device comprises a conduit having a choke therein and an enclosed diaphragm in communication with said conduit either side of said choke and sensitive to liquid flow therein.

No references cited.

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