US2893028A - Piston type soluble plug injector - Google Patents

Description

y 7, l959 D. SCARAMUCCI 2,893,028

PISTON'TYPE SOLUBLE PLUG INJECTOR Filed June 21, 1955 2 Sheets-Sheet 1 FIG. I.

wxwwwmsm INVENTOR ATTORNEYS July 7, 1959 D. SCARAMUCCI PISTON TYPE so'uusuz PLUG INJECTOR 2 Sheets-Sheet 2 Filed June 21, 1955 FIG. 3.

FIG. 7.

INVENTOR ATTORNEYS United States Patent PISTON TYPE SOLUBL'E PLUG INJECTOR Domer Scaramucci, Oklahoma City, Okla.

Application June 21, 1955, Serial No. 517,029

8 Claims. (Cl. 15--104.06)

The present invention relates to a piston type soluble plug injector for paraflin control and is adapted particularly for use in relatively small pipelines transporting crude oil. It is further characterized by utilization of liquid pressure as the operating medium.

The prevention of parafiin deposition in the piping systems of producing oil wells and in crude oil transporting lines is a major factor of expense to the oil trade. Hence considerable time and eifort are expended in operations for effectively controlling deposition of paraffin that would produce restriction of flow and finally cause total plugging of the lines. Such parafiin deposits comprise generally wax, gums, resins and asphaltic materials entrained in crude oil and disposed to crystallize and adhere to pipe walls in'regions of temperature changes.

The various methods employed in combating paraffin deposition include entraining chemicals with the crude oil to inhibit precipitation of wax crystals, continuous heating of oil, and periodic insertion of scrapers or plugs for travel with the flow in oil lines to shear paraflin deposition from wall surfaces before the accumulation reaches the point of substantial obstruction.

Where non-soluble plugs or scrapers are employed, they involve the problem of retrieval near the end of the line. Therefore an increasingly popular improvement has been the introduction of soluble plugs compounded of oil soluble materials. These soluble plugs are cylindrical in shape andof a length suitable for the intended purpose. When such a plug is inserted in a line it acts to shear the deposition during the course of its travel and will in due time dissolve so that there is no need for retrieving. Since the plug insertion operation must be performed every few days and offers quite a problem in the labor involved, there is considerable objection to more extensive application of. soluble plugs. The various injector devices and procedures presently in use also involve additional objections. line to provide an entrance for such plugs, the flow must be stopped and, during the plug insertion operation, considerable spillage occurs. This procedure is accordingly time consuming and generally unpopular. A more common practice comprises providing a by-pa'ss line equipped .with gate valves to divert flow during the plug injection operation. Although this avoids shutdowns, spillage and time consumption are still a problem.

A still further improvement concerns. plug injectors in the form of specially built three-way valves having a built-in by-pass system which enables the operator to rotate the valve port into alignment with the side opening of the valve. The plug can then be inserted while the flow of fluid is directed through the by-pass opening, and rotating the valve to normal position places the plug in the line of flow. This improvement also has inherent disadvantages of a substantial nature. One of these is a tendency for the fluid to move the plug prematurely as the 'valve is rotated to normal setting, which results 'in shearing or distorting of the plug in a way that mini Where a simple T1is installed in a mizes-itscifectiveness for parafiin removal. .Another is 2 the problem of the plug stalling in the port due to flow by-passing therearound in cases of low volume or low velocity flow rate, with the result that the plug dissolves in the valve and is wasted.

The principal object of this invention is to provide a method of injecting soluble control plugs utilizing hydraulic pressure means and operating in a rapid and simple manner without requiring shutting down, by-passing, or interrupting flow.

A more specific object of the invention resides in the provision of a plug injector comprising a plug transfer chamber containing a plug transferring device movable between plug receiving and flow line releasing positions in response to controlled flow line hydraulic pressure.

It is also another object to provide an injector of the character indicated that is semi-automatic in operation and so moves the plug to be injected into the flow line that any tendency to shear, distort, or stall in the injector is prevented.

A further important and specific object of the invention resides in the use of an unbalanced piston as the plug transfer means and by-passing means for moving the piston between its plug receiving and plug injecting positions.

Still another specific object is to provide, a piston type soluble plug injector of the character described that is free from leakage and has self-locking means controlled by fluid pressure for insertion of a plug into the transfer chamber.

These and other more specific objects contributing to efficient operation and reliability in use will appear from the following detailed description of a preferred embodiment and several modifications of the invention when taken in conjunction with the accompanying drawings, in which:

Fig. l is a top plan View of the plug injector of this invention;

Fig. 2 is a vertical longitudinal section of the plug injector of Fig. 1 taken on line 2--2;

Figs. 3, 4 and 5 are semi-diagrammatic side views of the injector of Fig. 1 and respectively showing the positions of normal flow line operation, plug injection operation, and transfer of a control plug from the piston transfer means to the oil flow line to be freed of paraifin deposition;

Fig. .6 is a vertical longitudinal section of a modified form of injector similar to that of Figs. 1 and 2; and

Fig. 7 is a vertical longitudinal section of an additional modified form of the injector illustrated by Figs. 1 and 2.

It is to be observed that the plug injectors to be described. in detail are designed for high pressure application in hydraulic oil well pumping systems in which the pressure is of the order of 3,000 p.s.i. and in which a su'bsurface pump is operated by a fluid power engine connected immediately above the pump. This engine is powered by pressured oil piped from the surface down to the pump in the well. The injector of this invention is installed at the well head on the power oil line' leading down the Well. These injectors are also to be used at the header .or manifold to provide for injection of plugs in the power oil lines leading to various wells being pumped with hydraulic subsurface pumps. It will also be understood that these injectors can be used in other high pressure crude oil lines.

In the drawings and with particular reference to Fig. 1, a piston type soluble plug injector designated generally by reference numeral 10 is shown to comprise an elongated plug transfer chamber 12 having a bored flange 14 on one end and a closed head flange 16 on the other with four stud bolts 18 passing between said flanges and provided at opposite ends with nuts 20. formain;

t-aining the flanges in tight relation over the respective ends of the chamber 12.

At the end of the transfer chamber 12 adjacent the flange 14 an upper flow port 22 and a lower flow port 24 extend through the walls of the chamber in Vertically aligned relation as shown. Adjacent the other end of the transfer chamber 12 a bore 26 adapted to receive a control plug is formed in th wall of chamber 12- with its longitudinal axis parallel to that of the aligned flow ports 22 and 24 at the other end of the chamber. In Fig". 2 there is shown a flow line FL threadedly connected in the flow port 22 and a surface line SL similarly connected in the flow port 24. The plug bore 26 is disposed opposite a much smaller drain port 28 usedto remove small amounts of fluid from the corresponding end of the transfer chamber 12, as will be more fully" explained.

The plug bore 26 extends outwardly of the transfer chamber 12 into an injector bonnet 3h formed as an integral boss and detachably receiving an injecter cap 32. The injector cap 32 is formed to provide an inner plunger end 34 carrying an O ring seal 36 engaging the adjacent portion of the bore 26. The cap 32 is also shaped to provide an enlarged, knurled knob formation 38 on its outer end.

The intermediate portion of the cap 32 within the horn net 34) is provided with diametrically opposite projections or lugs 4t), 40 fitting Within an undercut circumferential channel 42 of the bonnet and sized to pass through a diametrically opposed pair of slots 44, 44 in the top of the bonnet (Fig. 1), and communicating with the undercut channel 42 (Fig. 2). The construction which has been described provides a quickly detachable and self locking injector cap 32. In the relative position shown in Fig. 2 outward movement of the cap 32' in response to fluid pressure applied to its lower end by fluid in the communicating part of the transfer chamber 12 is prevented by the internal abutting relation of the lug projections, 40, in the channel 42. When, however, the external knob formation 48 is manually turned to align said lugs 40, 40 with the respective slots 44;, 44, the cap 32 may be readily removed for insertion of a soluble control plug P as indicated in Fig. 4.

In order to relieve fluid pressure from the portion of the transfer chamber defined by the adjacent part of the head flange 16 and beneath the bore 26, a standard drain valve 46 is connected with the relatively small discharge port 28 in the wall of chamber 12 so that drainage or discharge of fluid may be readily controlled by a hand wheel 47 with which the valve is provided.

One of the most important parts of the injector device 10 is a transfer piston 48 which reciprocates within the elongated transfer chamber 12 in a manner that will be largely apparent from a consideration of Fig. 2. Although functioning essentially as a free piston in the chamber 12, the transfer piston 48 is provided with an integral rod 50 extending through the head flange 14 in off-center relation to the axis of the cylindrical chamber 12 for the purpose of reducing the effective fluid pressure area at that end and limiting the motion to one of linear reciprocation. The other end of the piston 48 is formed with a spacer abutment 52 of reduced size for limiting contact with the adjacent reduced end 54 of the head flange 16. This end 54 is formed with a sealing groove 56 receiving an O ring seal 58 that acts against the inner wall surface of the transfer chamber 12. Intermediate its length and within the transfer chamber 12 the transfer piston 48 is formed with a bore or port 60 extending transversely therethrough and of a size to receive freely a soluble control plug P of similar shape and dimension. The port 60 is somewhat larger than the flow ports 22 and 24 which are aligned with its respective ends as shown most clearly in Fig. 2. The eccentric arrangement of the piston rod 50 prevents rotation of the transfer plug port 60 out of alignment with the flow ports and24 and also with the injector: bonnetbore 26 when 4 1 the transfer piston 48 is slid to a position of alignment therewith. bore 26 of chamber 12 has its axis parallel to that of said aligned flow ports 22 and 24 and is of a size to receive a control plug with sufficient looseness to insure ready discharge into the plug port 60 of piston 48.

Other means equivalent to the eccentric piston rod 50 may be used to prevent undesired rotational movement of piston 48.

For fluid tightness of the transfer chamber 12 the end of piston 48 adjacent the piston rod Si) is fitted with a spaced pair of composition piston rings 62, 62, as shown in Fig. 2, and outer and inner O ring seals 63 and 64 are fitted in the flange 14 to seal between the transfer chamber 12 and the piston rod 50, respectively.

Operation of the transfer piston 48 within the transfer chamber 12 depends on lay-passing of line fluid from the left end portion of said piston to the side of the piston adjacent the head flange 16, which is to the right as viewed in Fig. 2. For this purpose the lower flow port 24 may be spanned by a by-pass 66 shown as a groove in the bottom of the inner wall of the transfer chamber 12. A similarly arranged and formed groove 68 eX- tends between the inner end of the drain port 28 and inner end S4 of flange 16 to prevent fluid entrapment at that end of the chamber. Thus it will be understood that the piston 48 is of unbalanced design with the smaller area always acting against atmospheric pressure while the large diameter or area can be subjected selectively to atmosphere or line pressure. When the drain valve 47 is closed line fluid flows into the receiving chamber along the groove 66, rendering the piston 48 less effective as a seal means. As the pressure in the receiving chamber equalizes with the line pressure, or builds up suflic'iently to overcome the thrust from the flow line end, the piston 48 is moved into, or stays in ported alignment with, the flow entry and discharge lines FL and SL.

When the drain valve 47 is opened the pressure in the receiving chamber drops substantially to atmosphere, so

that the unbalanced piston 48 is moved into alignment with the plug injecting bore or port 26. At this time a control plug may be inserted by first removing the injector cap 32 (see Fig. 4). After the injector cap 32 is replaced, the drain valve 47 is again closed to trap the leakage of line fluid passing the piston and flowing into the receiving chamber. As the pressure of the trapped fluid builds up sufficiently in the receiving chamber adjacent the head flange 16, it Will overcome the thrust created by the line pressure so that the piston 48 will move to the left into ported alignment with the flow ports 22 and 24. This return movement results from the fact that the left or rod side of the piston 48 has less effective area exposed to flow line pressure. The constant exposure of the piston rod or small plunger to atmosphere throughout its path of movement thus makes it possible to unbalance the piston 48 to the left or right.

The fact that the leakage or by-passgroove 66 is-interrupted and terminates a substantial distance short of the position of the drain port 28 makes it possible to obtain a better seal with the transfer piston 48 when the latter is in the injection position of Fig. 4, and the piston rings 62 are clear of the groove. Otherwise the fluid leakage would be sufficient to overflow the injection port or bore 26* as plugs are inserted. A perfect seal is undesirable because some fluid must by-pass to fill 'the receiving chamber and build up pressure to return the piston after the drain valve 47 has been closed. After slight movement of the piston 48 to the left exposure of the groove '66 will permit fast leakage to speed the movement of the piston and thus achieve the principal purpose of the groove. The groove as such is not a necessary feature since leakage or by-passing of fluid in order to perform the plug transfer operation can be obtained in other ways, the practical, rather than perfect sealing between It is to be observed that the plug receiving.

3 the right hand head end of the piston 48 and the chamber 12 will suflice for by-passing. The manner represented by the groove 66 has been found to be the most practical.

It should also be noted in this connection that suflicient opening is provided at the flow ports 22 and 24 regardless of the position of the piston 48, and that the piston section carrying the piston rings 62 is sufiiciently narrow to permit flow as it moves across said ports.

By way of summary and elaboration of what has been explained as to the operation of the plug injector of this invention, it is observed that Fig. 3 shows the injector device 10 in normal operating position with the transverse port 60 of the unbalanced piston 48 in line with the line fluid indicated by heavy arrows; Fig. 4 illustrates the operation of inserting a plug P with drain valve 46 open and the injector cap removed; and Fig. 5 illustrates the condition of the injector device after pressure build-up created by controlled leakage past piston 48 forces the piston containing a plug P to return to a normal operating position for releasing the plug into the line denoted by heavy arrows.

Two modifications of the injector device of this invention are shown in the embodiments illustrated somewhat diagrammatically in Figs. 6 and 7 respectively.

' .In Fig. 6, 22a denotes the flow port on the upper side and 24a the flow port on the lower side. The injector cap is 32a, the drain valve is 4611, and the transfer piston isfl48a, and has a transverse plug port 60a. A pilot valve 70 slides in the piston rod 50a and has an outward- 1y extending end 72 for manual operation and an inner enlarged head or valve closure member 74 movable back and forth in an enlarged chamber 76 to open or close a port 78 leading to the plug port 60a. A conduit80 formed in the piston 48a connects the valve chamber 76 with the space on the rod side of the piston 48a. The pilot valve 70 is normally maintained closed, but it can be momentarily opened to divert pressure fluid from the line to produce a pressure balance after the drain valve 46a has been closed. The remaining operation of the injector device of Fig. 6 is substantially the same as described for the principal embodiment.

Even less modification of the injector device of Figs. 1 and 2 is involved in the embodiment of Fig. 7. In this somewhat diagrammatic figure the upper and lower flow ports are designated 22b and 24b respectively, the injector cap is 32b, and the drain valve is 46b. A transfer piston 48b is provided with a piston rod 50b and a transverse plug port 60b as before. Instead of the fluid bypass groove 66 of Fig. 1, an equivalent action is obtained through the use of a small orifice 66b extending between the plug port 60b of the transfer piston 48b through which controlled pressure fluid leakage is permitted.

The attainment of the inventive objects set forth and the advantages of the control plug injector of this invention may be summarized as follows. The pressure line flow through the injector device is neither blanked oif nor interrupted during the operation thereof. The transfer chamber 12 provides a closure for receiving the piston port 60 and thus confines the expanding gaseous fluid and diverts it through the drain port 28 as the piston moves to the plug receiving position. The piston moves the control plug automatically into the pressure line without the necessity for separate manual manipulation.

A novel method of feeding the control plug to the pressure line by utilization of available hydraulic fluid pressure has been provided.

Through this invention there has been provided a dependable and efficient plug injector for paraflin control in oil flow lines, and one which is simple and rapid in operation. The problems of damage to soluble plugs and the tendency of plugs to stall in many of the previously used types of injectors, and dangerous spilling of inflammable fluid or release of expanding gaseous fluid in an objectionable manner have all been overcome.

escapee While the preferred form and several modifications of this invention have been fully disclosed, it is to be understood that various changes may be made in the mode of operation and in the construction and arrange ment of parts that will obtain equivalent results Without departing from the invention as claimed.

Having thus described my invention, What I claim as novel and desire to secure by Letters Patent of the United States is: i

1. An injector for soluble control plugs comprising an elongated plug transfer chamber having a transversely aligned pair of flow ports adjacent one end thereof, a nonturning, free piston biased toward the flow ports end of said chamber by a relatively larger effective end area remote from said flow ports end and having a transverse transfer port arranged to align with said flow ports when the transfer piston is at said flow ports end of the transfer chamber, the plug transfer chamber being formed with a transverse plug receiving bore in the wall thereof adjacent to the opposite and piston end of said chamber and having its axis parallel to that of said flow ports, a removable injector cap detachably secured in the plug receiving bore, the said piston including means for leaking fluid from said flow ports past the piston to act on the larger area head end thereof, and drain means communicating with the plug transfer chamber adjacent the piston end thereof for relieving pressure between said transfer piston and the last-mentioned end of the transfer chamber.

2. An injector for soluble control plugs comprising, an elongated closed piston chamber; a free piston reciprocable in said chamber and formed with a transverse plug receiving port, one end portion of the wall of the piston chamber being provided with a lateral bore having a detachable closure and being adapted to receive a control plug and disposed for alignment with said plug receiving port when said piston is moved to the corresponding end, and the other end portion of the piston chamber wall being provided with opposed flow ports arranged for alignment with said plug receiving port to discharge the plug when said piston is moved adjacent thereto, the said piston having a larger effective end area adjacent said one end portion of the chamber and being thereby biased toward the flow ports end portion and constructed for leakage of pressure fluid from the flow ports into said one end portion of the piston chamber; and drainage means at the end portion of the piston chamber having said plug receiving bore.

3. An injector for soluble control plugs comprising a closed piston chamber; an unbalanced piston freely reciprocable in said chamber and formed with a transverse plug receiving port, one end portion of the lateral wall of the piston chamber being provided with a lateral bore having a detachable closure and being adapted to receive a control plug and disposed for alignment with said plug receiving port when said piston is moved to the corresponding end, and the other end portion of the piston chamber wall being provided with opposed flow ports arranged for alignment with said plug receiving port to discharge the plug when said piston is moved adjacent thereto, the said piston having a larger effective end area adjacent said one end portion of the chamber and being biased toward the flow ports end portion, said chamber being formed with a by-pass groove in its inner wall surface for leakage of pressure fluid from the flow ports into said one end portion of the piston chamber; and valved drainage means at the same end portion of the piston chamber.

4. An injector for soluble control plugs comprising a closed piston chamber; a pressure unbalanced piston having unequal effective end areas freely reciprocable in said chamber and formed with a transverse plug receiving port, one end portion of the wall of the piston chamber being provided with a bore adapted to receive a control plug and disposed for alignment with said plug receiving port when said piston is moved to the corresponding end, and the other end portion of the piston chamber wall being provided with opposed flow ports arranged for alignment with said plug receiving port to discharge the plug when said piston is moved adjacent thereto, the said piston being biased toward said other end portion and having a small orifice therein for leakage of pressure fluid from the flow ports into said one end portion of the piston chamber; a closure for the control plug bore and valved drainage means at said one end portion of the piston chamber.

5. An injector for soluble control plugs comprising an elongated closed piston chamber; a free, pressure unbalanced piston reciprocable in said chamber and provided with a piston rod on one end, a head on the other, and a transverse plug receiving port, one end portion of the wall of the piston chamber being provided with a bore adapted to receive a control plug and disposed for alignment 'with said plug receiving port when said piston is moved to the corresponding end, and the other end portion of the piston chamber wall being provided with opposed flow ports arranged for alignment with said plug receiving port to discharge the plug when said piston is moved adjacent thereto, the said piston being biased toward the flow ports end portion and the piston rod extending through the same end of the piston chamber, and said piston being formed with a valve chamber communicating by ports with the plug 'bore thereof and with its 'rod end; a pilot valve sliding within the piston 'rod to open and close the port to the plug bore; a closure for the control plug bore; and valved drainage means at the end portion of the piston chamber having said -plug receiving bore.

*6. An injector for soluble control plugs comprising an elongated plug transfer chamber having a transversely aligned pair of flow ports adjacent one end thereof, a non-turning, free transfer piston receiprocable in said chamber biased towards the flow ports by a relatively larger effective end area remote from said flow ports end and formed with a projecting abutment on the end remote from the flow ports, a transverse transfer port in the piston arranged to align with said flow ports when the transfer piston is at the flow ports end of said transfer chamber, the plug transfer chamber being -formed with'a transverse plug receiving bore in the lateral wall thereof adjacent to -but spaced from the end of said chamber remote from said flow ports and having its axis parallel to that of said aligned flow ports, an injector cap member detachably secured in the plug receiving bore, means formed between the transfer piston and the transfer chamber for leaking fluid from said flow ports past the piston to act on the abutment end thereof, and drain valve means connected with the plug transfer chamber adjacent the end remote from said flow ports end for relieving pressure between said transfer piston and the last mentioned end of the transfer chamber.

7. The combination as defined in claim 6 in which the injector cap is provided with opposed lugs and the plug receiving bore has slots at its .outer end and is formed with an undercut annular channel communicating with said slots for loosely receiving said lugs, whereby fluid pressure on the inner end of said cap will prevent detachment when the lugs are within said channel.

8.. An injector for soluble control plugs comprising an elongated plug transfer chamber having a transversely aligned pair of flow ports adjacent one end thereof, a non-turning, free piston reciprocable in said chamber biased toward the How ports end of said chamber by a relatively larger effective head end area remote from said flow ports end and having a transverse transfer port arranged to align with said flow ports when the transfer piston is at said flow ports end of said transfer plug chamber, the plug transfer chamber being formed vw'th a transverse plug receiving bore in the lateral wall thereof adjacent to the end of said chamber remote from said flow ports and having its axis parallel to that of said flow ports, a removable injector cap detachably secured in the plug receiving bore, said transfer chamber being formed with means for leaking fluid from said flow ports past the .piston to act on the head .end thereof, and drain means communicating with the plug transfer chamber adjacent the end remote from said flow .ports for relieving pressure between said transfer piston and the end of the transfer chamber.

References Cited in the file of this patent UNITED STATES PATENTS 682,985 Gray Mar. 25, 1902 12,493,504 Roberts Jan. v3, 1950 2,651,325 Lusignan Sept. 8, 1953 2,790,500 Jones Apr. 130, 1957 FOREIGN PATENTS 119,058 Germany ..of 1901 309,344 Great Britain Apr. 11, .1929

436,830 :Italy June 14, 1948

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