US3319572A

US3319572A - Free piston

Info

Publication number: US3319572A
Application number: US502758A
Authority: US
Inventors: Lyles Cecil Ray
Original assignee: UNITEX ENGINEERING SERVICE Inc
Current assignee: UNITEX ENGINEERING SERVICE Inc
Priority date: 1965-10-18
Filing date: 1965-10-18
Publication date: 1967-05-16
Anticipated expiration: 1984-05-16

Description

C. R. LYLES May 16, 1967 FREE PISTON 3 Sheets-Sheet 1 Original Filed June 13, 1960 CECIL RAY LYLES INVENTOR.

ATTORNEY May 16, 1967 c. R. LYLES 3,319,572

FREE PISTON Original Filed June 13, 1960 3 Sheets-Sheet 2 F|G5 3 H7 4 7a AP ///A\ 4 FIG 3 IZO/ Q/Fh

I69[" /H I7 57 99 26 L5: VII

53 v INVENTOR.

ATTORNEY CECIL RAY LYLES y 6 1967 c. R. LYLES 3,319,572

FREE PISTON Original Filed June 13, 1960 3 Sheets-Sheet 5 V CECIL RAY LYLES INVENTOR.

ATTORNEY United States Patent O 3,319,572 FREE PISTON Cecil Ray Lyles, Farmington, N. Mex., assignor to Unitex Engineering Service Inc, Perryton, Tex., a corporation of Texas Continuation of application Ser. No. 35,831, June 13, 1960. This application Oct. 18, 1965, Ser. No. 502,758 Claims. (Cl. 103-52) This application is a continuation of my pending patent application Serial No. 35,831 filed June 13, 1960.

This invention relates to free pistons for raising natural oil and other liquids in wells wherein in a slug of liquid is lifted up an oil eduction pipe to the well surface by gas or oil pressure. According to the invention herein a free piston is made which is adapted to travel up and down in a liquid eduction pipe of a well. Means are provided for reversing its travel at the upper and lower limits of its travel.

In the producing of oil and water wells, free pistons have been employed to provide a solid divider by means of which such liquids have been lifted with a gas. Such gas may be supplied to or exist in the liquid in the eduction pipe. When the gas which lifts the liquid slug up the pipe is in direct contact with the base of the liquid slug to be raised thereby, some penetration of the gas into the column of liquid or liquid slug may take place. This tends to produce breakages in the column and a resultant loss in efiiciency. To prevent this, it is common practice to provide a movable piston adapted to be positioned in the lower end of the eduction pipe while the slug is being collected in the eduction pipe. The piston is then adapted to rise vertically in the pipe beneath the liquid slug. The piston thus isolates the base of the liquid slug from the gas which lifts such slug. The piston is arranged to subsequently fall down the pipe by gravity after the slug of liquor has been delivered to the surface.

Pistons of this type are used to raise liquid through an eduction tubing, with the piston traveling substantially the full length of the eduction tubing. Since the tubing is composed of sections of pipe joined by threaded couplings, the construction of the piston must be such that it will not be caught or jammed when passing over a joint between such tubing sections. However, in order to minimize slippage and consequent loss of oil fluid the piston must maintain a seal with the inside surface of the sectional eduction tubing. The piston construction disclosed according to this invention meets these requirements while also not requiring a large number i of parts.

\Vhile various sealing devices have been proposed for such pistons, such sealing elements have at least one common feature which makes them impractical to be used in some wells. In those wells which produce solids such as wax and paraflin, the free pistons sealing elements heretofore used have generally been unsatisfactory due to accumulation of the solid in the seal. This accumulation sooner or later causes malfunction of the free piston and required attention or maintenance.

Devices of the prior art have had a fixed external diameter as in U.S. Patents 2,762,310; 2,684,633; 2,688,- 923; and 2,001,012. These provide a piston of variable cross-sectional area by moving blocking materials from the center thereof: this permits the well fluid to flow past the interior of the piston. This allows the piston to travel downward against the upward fiow of the well fluid. Such internal by-pass devices, of course, provide considerable turbulence in the flow therethrough, especially at the valve ports of such devices near whereat paraflin accumulates and subsequently interferes with the operation of such devices. It is, therefore, an object of this invention to provide an improved free piston which is not encumbered with such disadvantage.

Furthermore, the paraflin deposition on well tubing, due generally to the cooling of crude oil containing paraifin and the subsequent deposition on the tubing of such paralfin has been a problem in the art. This invention is directed, also, to an improvement in tubing scrapers which will reciprocate in the tubing automatically and remove such deposits. A main difliculty with the previous automatic scrapers has been that they did not fall through the rising oil fluid with suflicient velocity to trip a mechanism which packs off or plugs flow through and around the scraper and cause it to be forced to the surface with well fluid. The device of this invention has suflicient change in cross sectional area to travel downward through the tube with a sufficiently substantial velocity adequate to trip such mechanism. The device of this invention is, also, sufiiciently sturdy to suffer such velocity and impact.

It is, therefore, one object of this invention to provide an improved free piston which automatically reciprocates in oil well tubing.

It is an object of this invention to provide a piston construction of a reduced number of parts which simplifies its procedure of manufacture, assembly, and maintenance.

It is, also, an object of this invention to provide an improved scraper for removing deposits from inside of vertical oil well tubing tube.

Yet another object of this invention is to provide an automatic tubing scraper which will automatically return to the surface from the bottom of the well or some intermediate point in the well.

These and other objects of the invention will become apparent from the following description, wherein the accompanying drawings, which are a part of the dis closure herein are included and in which:

FIGURE 1 is an overall side View of the device of the invention herein shown in its expanded form;

FIGURE 2 is an overall diagrammatic central longitudinal sectional view of the device of FIGURE 1;

FIGURE 3 is an overall side view of the device of the invention in its contracted form;

FIGURE 4 is an enlarged diagrammatic longitudinal sectional view of the elements and connections of a piston in the device of the invention in its expanded form;

FIGURE 5 is an enlarged diagrammatic longitudinal sectional view of the elements and connections of a piston of the device of the invention in its contracted form;

FIGURE 6 is a diagrammatic side view of the piston of FIGURE 5 generally as seen along the plane VI'VI" of FIGURE 5;

FIGURE 7 is a diagrammatic side view of the expanded piston of FIGURE 4 generally as seen along the plane VIP-VII" of FIGURE 4;

FIGURE 8 is an end view of the device of FIGURE 1 as seen along plane VIIIVIII" of FIGURE 1;

FIGURE 9 is a top view of an alternative form of piston along section IX'IX" of FIGURE 10;

FIGURE 10 is a sectional longitudinal view through plane X-X of FIGURE 9;

FIGURE 11 is a diagrammatic central longitudinal view, partly in section, of a well and tubing wherein the device of the invention herein is employed.

Generally, the device of the invention herein described comprises a hollow steel shell or tube which contains in its walls sealing and scraper elements and, in the hollow of the shell, means for moving such sealing elements radially. The device is particularly adapted for use as a free piston operating in oil and gas wells which produce paraffin or other solids. Reference is made to the drawings for some details and overall views.

As shown in the drawings, the device comprises a hollow tube, 11, having a substantial wall thickness. A series of contiguous wedge plates, as 45, 46, 47, and 48, (as shown in FIGURE 2) is located in the interior chamber, 50, of the tube, 11. Each member of this series of plates is releasably held in one of two positions, depending on the actuation applied to such series by either of the elongated actuating rods, 27 and 28, one of which projects beyond each end of the tube. The wedging plates actuate expansible pistons such as 16, 17, 18, and 19, to move to their expanded positions (shown in FIGURES l, 2, and 4) from their contracted positions (shown in FIG- URES 3 and 5) and vice versa, as below described. Extending between the pistons on the external portion of the hollow tube, 11, are a plurality of ring segments, 19, 20, 21, 22, 23, 24, 25, and 26 which have a peripheral circular outline as shown in FIGURE 8. These segments each are provided with seats in the exterior wall of the tube, 11. When located in such seats the peripheral surface of each such segment lies in or slightly beneath the surface of the outer wall of the tubing, 11. Each end of these segments is slidably attached to a piston near an end of such piston.

Each expansible piston, as 16, 17, 18, and 19, is made of two principal segments. Thus, piston 17 comprises two L-shaped paired segments, 99 and 100 (as shown in FIG- URES 6 and 7). Each piston element, as 99, comprises a transversally extending head, 104, and a vertically extending body, 105. Element 100 is a duplicate of element 99. A pin, 101, extends from head 104 into a slot, 102, therefor in element 100. This pin is provided with a shoulder, 106. A spring, 103 in slot 102 provides a compressive force between the shoulder, 106, of the pin 101 and the base of the cylindrical slot, 102, wherein pin 101 closely but slidably fits. Piston element 100 has a pin, 107, corresponding to pin 101. This pin 107 slidably fits into a slot therefor in element 99. A shoulder on pin 107 is provided as on pm 101 and with a spring as 103. The position of circular slot 102 is similar to slot 202 and 302 shown for one element of

pistons

18 and 16, respectively, in FIGURE 2.

A Wedge plate, as 47, is placed between each of the paired piston elements, as 99 and 100. Each such wedge plate, as 47, is rectangular on side view (FIGURES 2, 4, and 5) and flat except for laterally extending wedging guides, as 47A and 47B, one on each side of the plate 47. Both such wedge guides have equal and uniform thickness. They slope in equal amounts but in opposite directions. Thus guide 47A slopes upwardly and rearwardly while guide 473 slopes downwardly and rearwardly (regarding shaft 27 as the front shaft and top as shown in FIG- URE 2).

Guides

47A and 47B fit into similarly sloped slots 112 and 111, respectively, on

faces

113 and 98, respectively of

piston elements

99 and 100. Accordingly, a

. rearward axial movement of a wedging plate, as 47, causes the

piston elements

99 and 100 associated with such wedge plate to come together; forward motion of the Wedge plate causes the

piston elements

99 and 100 to move away from each other.

As the slope of wedge guide 47A is the same as that of wedge guide 4713 relative to the longitudinal central axis of tube, 11, and as the slots 112 and 111 for such guides in piston 17 are also rectilinear and have the same slope relative to said axis of tube 11 as the wedge guides 47A and 47B fitting thereinto, the expansion of the components of piston 17 directly depends on the axial forward or backward motion and \position of the wedge plate 47 (with its

guides

47A and 47B) fitting thereinto. The

wedge plates

45, 46, 47, and 48 are all of the same size "and shape. Also, as shown FIGURE 2, each wedging

plates

45, 46, 47, and 48 is in contact with adjacent plate. Thus, movement of one plate moves the entire line of plates and causes all the pistons (and their associated ring segments) to move toward the contracted or expanded position at the same time and in the same amount. The

pistons

15, 16, 17, and 18 are also of the same size and shape. Thus motion of all the pistons is the same on equal movement of the wedge plate and guides therefor relative to such pistons. The

pistons

15, 16, 17, and 18 are slidably yet firmly held in

cylindrical sockets

115, 116, 117, and 118, respectively, located in the wall of the tube, 11, and passing therethrough. The central axes of pistons 15 and 17 are parallel to each other as are those of

pistons

16 and 18. The central axes of pistons 15 and 16 are perpendicular to each other; however, the central axes of all the

pistons

15, 16, 17, and 18, are all normal to the central longitudinal axis of tube 11, and the

wedge plates

45, 46, 47, and 48 fit firmly yet slidably in the cylindrical hollow portion, 50, of tube 11, with the length of said plates lying parallel to the central longitudinal axis of said tube 11. Accordingly, a given axial movement of the

shaft

27 or 28 causes the same radial movement of all of the

pistons

15, 16, 17, and 18.

Slot 57 of piston 17 holds the tongue 69 of the segment 25 and corresponding tongue of segment 23. Corresponding ring segments are held into similar piston slots in all the other pistons, as 15, 16, 17 and 18, and slots as and 57 are also present on each end of all such pistons, as shown in FIGURES 2, 4, S and 7.

The ring segments, 19, 20, 21, 22, 23, 24, 25, and 26, which are each slidably attached near to the end of two of the pistons, as 15, 16, 17, and 18, move radially when the ends of such pistons are caused to move radially to their expanded position (of FIGURES 2, 4, and 7) by the action of the wedge plates. Additionally, these ring segments move centrally when the pistons are moved to their contracted position as shown in FIGURES 5 and 6 by the action of the wedge plates, 45, 46, 47, and 48. This radial motion of the ring segments causes the effective cross sectional area of the device to increase substantially, as shown in FIGURE 8, over the cross sectional area of the tube 11 alone.

It will be noted that each spring element, as 103, serves to provide a smooth fit of each corresponding piston body, as 105, against the central edge of a wedge guide, as 47A, by pressing the piston head, as 104, away from the wedge plate, as 47. This resilient urging avoids rattling between the piston elements, as 99 and 100, and the corresponding wedge plate. Such spring element thus provides for smooth fit of the segment element against the wall of the tubing as 82. Thus fit is a smooth tit and is sufiiciently firm to remove parafiin from the well tubing walls as well as sufiiciently close to form a good seal to prevent gas bypassing such seal, and sufiiciently light to allow a slidable fit of the device in the well tubing, as 82.

The ring segments, as 23, 24, 25 and 26, in cooperation with the pistons associated therewith, as 17 and 18, form a complete ring around the tube 11. Such ring has a larger diameter than the tube, 11. The ring thus formed, as seen in FIGURE 8, has a cross sectional area of 40% larger cross sectional area than the cross sectional area of the tube, 11, for the embodiment whose dimensions are below described in detail. Such a large change in cross sectional area allows such a piston to fall rapidly through even a well tubing through which there is, simultaneously, a rapidly rising flow of oil. This rapid fall provides the energy to trip the mechanism that causes the ring segments to reach their expanded position.

It will be noted that when the ring segments are moved outwardly by the radially expanding pistons (to which pistons each such segment is attached) the circumference of the surface of such segments and piston, as viewed in FIGURE 8 increases from 1rD (D=diameter of the tube, 11) to 1rD (where D is tip-to-ti'p distance across a piston, as 17).

A tongue is provided at each end of each ring segment, as 69 for segment 25. This tongue projects beyond the shoulder, as 169, on each end of each such segment sufliciently far to provide a firm support of each end of the segment in the corresponding slot as 57, in the head of the piston which supports each end of such ring segment, as piston 17, when such piston is expanded, as in FIG- URE 4. When such piston contracts, as in FIGURE 5, the distance between shoulders on each segment is the distance, across the exterior face of such segment, as face 123 of ring segment 23, between the pistons, as 17 and 18, supporting such segment. This arrangement avoids that the radial motion of the pistons as 17 and 18 suffers any interference because of the presence of the associated ring segment, as 23.

The peripheral surface of each ring segments is curved so that such peripheral surface, as 119, 120, 123, 124, 125, and 126 (for

segments

19, 20, 23, 24, 25, and 26, respectively) sufficiently closely matches the 2 inch internal diameter surface of a well tubing, as 82, as to form a firm yet slidable seal adequate for improving the efficiency of flow from said well and through said tubing 82. The ring segments (19, 28, 21, 22, 23, 24, and 26), are each provided with corresponding grooves (219, 220, 221, 222, 223, 224, 225, and 226, respectively) in the wall of tube 11 into which these segments each fit on movement of the expansible piston associated with such segments to their contracted form, as in FIGURES 3 and 5; therebly the most radially located portions of each of such segments will lie not beyond the outer surface of the tube 11. These grooves are sufdciently deeper than the thickness of each such segment to allow for that the radius of curvature of the outside of the segment is greater than the outside radius of curvature of the tube, 11. This depth of groove for each segment permits that the peripheral surface of each segment may fit the adjacent inner surface of the well tubing 82 and each of the combinations of all the connected segments with the pistons connected therewith, as

segments

23, 24, 25 and 26 with

pistons

17 and 18, and

segments

19, 20, 21, 22 with the pistons 15 and 16, form a circumferential seal between the tubing 11 of the free piston 81 and the interior surface of the well tubing 82. Each such seal is substantially complete and continuous. The small space between the shoulders of the ring segments and the corresponding piston shown in the embodiment of FIGURES 1 through 8 is avoided in the embodiment of FIGURES 9 and 10.

The tops of each of the pistons, as 17, have a curvature on the tops of the piston heads, as 104, to also fit the interior surface of the well tube, as 82. The dimensions of the wedge plate and the slope of the wedge guide and the corresponding slope of the groove in each of the piston body sections, as 105, of each portion of the expansible pistons, as 99 and 108, is arranged so that each piston and ring segments associated therewith is withdrawn entirely within the outer surface of the hollow tube, 11, when the series of

wedge plates

45, 46, 47, and 48 is moved by the actuating shaft 27 so that the entire device, 81, may travel downwardly through the well tubing.

The wedge plate series positioning element, 72, has an interior surface 73 which is conical shaped, and expands to the rear. This comically shaped interior portion 73 has a front groove 75 for front positioning piston 29 to hold the series of

wedge plates

45, 46, 47, and 48 in a position for holding expansible pistons 15, 1'6, 17 and 18 in their expanded position as shown in FIGURE 2, and a rear groove, 76, for holding the front positioning piston 28 in a location providing for the contracted form of the pistons as shown in FIGURES 3 and 5. A circular groove as 77 is also provided in the rear of tube 11 for holding rear positioning piston 30, as shown in FIGURE 2, in a position that cooperates with the location of front piston 29 in front locking groove 75. The rear locking groove 76 is similarly provided in element 72 to cooperate with the rear locking groove 78 for piston 30 to hold

expansible pistons

15, 16, 17, and 18, in their contracted form. The distance between the locking grooves 75 and 76 (and 77 and 78) is chosen to cooperate with the lengths of the wedge plates (45, 46, 47, and 48) and the slope of the wedging guide element (45A, 46A, 47A, and 48A and 45B, 46B, 47B and 4813) to allow for such amounts of expansion of the ring segments as is required to match the internal diameter of the well tubing 82. The diversion of the conical wall of the surface 73 is slight (about 5) to facilitate snap-locking of the spring loaded locking element 96 and 97 in

pistons

29 and 38 respectively, in one set of locking grooves (as 76 and 78) or the other (as 75 and '77). The spring loaded locking means may be annular springs or diametral springs (passing through holes in pistons 29 and 38) with steel balls of about 7 diameter at the peripheral ends thereof.

Bumper blocks or shoulders, as 129 and 130, are attached to elements as 14 and 12 at the ends of the tubing, 11, to facilitate positive seating of the positioning pistons 29 and 30 in one position or the other. This also avoids the jamming of the

piston elements

15, 16, 17, and 18 on the wedge guide associated with such pistons. Positioning pistons 29 and 30 slid'ably fit into the hollow 50 of tube 11.

In its operation, the free piston, shown as 81 in FIG- URE 11, when in its expanded form fits closely against the interior of the tubing 82 of the oil well (which well is shown generally as 83 with a packer This fit is due to the sealing action of the

ring segments

19, 20, 21, 22, 23, 24, 25, and 26 as above described. The free piston is driven upwardly by the pressure of the fluid in the oil well. The fluid rises to the top of tubing 82 for delivery from the outlet pipe 87. When the free piston 81 approaches the top of tubing 82, a stop, as 85, which is firmly attached to a cap as 86 contacts the extending front activating shaft 27 of the free piston 81. Then the momentum of the piston 81 causes the shaft 27 to be moved from the position shown in FIGURE 1 to that shown in FIGURE 3. Thereupon, as above described, the

segments

19, 20, 21, 22, 23, 24, 25, and 26 move from the expanded position of the segments shown in FIGURE 1 to the contracted position of the segments shown in FIGURE 3. The tripping of the shaft 27 and the rearward movement of the series of the

wedge plates

45, 46, 47, and 48 connected thereto, decreases the outline of cross-sectional area of the piston from that shown in FIGURE 8 to that of the tube 11 alone. This provides a substantial decrease in area (depending on particular dimensions of the device) of the cross sectional area of the piston, as seen along shaft 28 and shown in FIGURE 8. The cross sectional area change may be from 20% to 40% of the cross sectional area of tube 11. The piston then falls through the liquid in the oil well tubing to the bottom of that tubing to the location of a bottom stop, as 88, which may be a collar stop usually located near to the bottom of the well tubing, 82. The collar stop is usually located between two sections of tubing or between tubing and a strainer pipe and fixed in position by a coupling, as 89. Conventionally, a strainer, as 91, is attached below the stop. The momentum of the falling piston provides an impact on the lower end of the pin 28 of the device suflicient to change the position of that pin from that shown in FIGURE 3 to that shown in FIG- URES 1 and 2.

- The expansible ring segments are attached to and controlled by the motion of the

expansible pistons

15, 16, 17, and 18. The motion of these pistons is in turn controlled by the action of the guides on the wedging

plates

45, 46, 47, and 48. The action of each of these guides on the wedging plates is in turn controlled by the location of the expansible pistons as 30 (attached to shaft 18) and 29 (attached to shaft 27). When shaft 28 is moved to a location corresponding to the front of the expanded free piston shown in FIGURES 1 and 2, once again the piston outline fits against the inner wall of the oil well tubing 82 and the free piston 81 7 again rises through the tubing under pressure from the liquid therebeneath.

In an exemplary form of the invention, the free piston 81, for use in a 2 inch internal diameter well tubing 82, comprises a hollow steel body tube, 11, which is 15 long, has a inch internal diameter and a 1 inch outside diameter. The conventional top plug and fishing neck, 12, is 4 inches long and is provided with a 1 /8 inch neck diameter and a /2 inch long fishing neck collar, 13, of 1% inch diameter. The end plug, 14, is 1 inch long and has the same outside diameter as the body 11. The expansible pistons, 15, 16, 17, and 18, are each diameter, with a 2 inch expanded length and l V inch contracted length. They support the ring segments, as 19, 21), 21, 22, 23, 24, 25, and 26, in slots as above described. The front actuating shaft or stinger 27 has a inch outside diameter; It projects from top plug 12 about 1 /2 inches when free piston 81 is in its expanded form as shown in FIGURE 1. The rear or bottom actuating shaft 28 inch diameter) then projects inch from rear or bottom plug 14.

Sleeves

93 and 95 provide a firm yet slidable fit for such shafts. The positioning pistons 29 and 30 are driven by

shafts

27 and 28, respectively. It is 21 inches from rear of plug 14 to the front of collar 13. The longitudinal center of expansible piston 15 is 12% inches from rear end of plug 14; the longitudinal center of expansible piston 16 is 10% inches from the rear end of the plug 14;. the longitudinal center of expansible piston 17 is 7% inches from the rear end of plug 14; and the longitudinal center of expansible piston 18 is inches from the rear end of plug 14. (The longitudinal center is the longitudinal central axis.)

Ports, 31, 32, 33, and 34, are J inch in diameter and are provided through wall of tube 11 for pressure release around positioning pistons 29 and 3t).

Guards

35, 36, 37, 38, 39, 4t), 41, and 42 are provided in line with the expansible pistons. The guards are each 1% inches overall length, inch wide, and project laterally inch from the outer wall of tube 11. Center of

guards

35, 36, 37, and 38 are 14% inches from rear end of plug 14. Center of

guards

39, 40, 41, and 42 are 3% inches from the rear end of plug 14. The positioning pistons 29 and 30 are respectively provided with spring loaded expansible lock rings 96 and 97 that fit into

respective locking grooves

75 and 77 or 76 and 78 corresponding, respectively, to the forward and rear positions of

shafts

27 and 28. The centers of the locking grooves 75 and 76 are 1 inch distant from each other as are the centers of

grooves

76 and 78.

Wedge plates

45, 46, 47 and 48 are each 2 /2 inches long and A; inch high, and are each respectively provided laterally with diverging

guides

45A and 4513, 46A and 4613, 47A and 47B, and 48A and 4813. The guides are each /s inch wide and inch high, the height being measured parallel to the face of the wedge plate, which plate is inch thick. The wedge plates are inch high and are each curved at their top and bottom edge so as to slidably fit in the interior of tube 11 (fit of .005 inch to .010 inch). These guides freely fit into grooves, as 111 and 112, in the faces, as 113 and 98, respectively, of L-shaped piston segments as 100 and 99. These grooves are wider and deeper than the guides to provide a freely slidable fit therewith.

The L-shaped elements, 99 and 100, of each expansible piston, as 17, each have a head, as 104, that is 1 8 inch thick. Such head laterally projects inch beyond the flat face of the associated semi-circular section body portion as 105, which body portion is (including the head) 1% inch long; this latter portion, 105, on its fiat face, as 98 for element 99 of piston 17, has a slot, 112, whose top edge runs from about inch at one side to about /a inch at the other side of said face from the base of the head. The bottom edge of said slot correspondingly runs from inch to inch from the base The slope of'these slots match the slopes of the guides, as 47A or 47B as shown in FIGURES 2, 4, and 5. A /s inch diameter pin, 101, projects from the head of each piston head, as 104, into a slot, as 182, in the semi-circular portion of the other piston element, 100, as shown in FIGURES 4 and 5. A spring, 103, therein urges each expansible piston to expand and provide I guide and the slot therefor. The wedge guides are so sloped that a 1 inch axial travel of the

positioning pistons

27 or 28 causes the total desired radial expansion of 7 inch of each of the

expansible pistons

15, 16, 17 and 18. This arrangement also provides that the force which brings the expansion pistons into their final expanded position is the spring therefor, as 103. Accordingly, any initial shock met by the ring segment associated with each expansible piston, as 17, is absorbed by the resilient spring, as 103, and not by the more rigid wedge and wedge guides. Thus, the impact with which the piston hits the stop at the bottom or top of the oil Well does not control the final expansion of the expansible pistons as such is controlled by such spring and is not directly tied to the amount of the impact.

Expansible piston slot, as 57, holds to tongue, as 69, of two ring segments, as 23 and 25. Corresponding ring segments are held in and moved by ring segment piston slots in the other expansible pistons. as 57, are s inch deep and the center of the depth of each slot is inch below the top of each such piston element, as 99. The ring segments are each inch deep, slightly less than inch Wide and, exclusive of tongues, are each 1% inch long between pistons. These segments each' travel radially inwardly and outwardly about 4 2 inch through inch wide slots, as 225 for segment 25, in tube 11 when so urged by the expansible pistons to which such segments are attached. The spring loaded pistons thus finally urge those ring segments into smooth slidable contact with the oil well tubing wall 82 in the expanded position of those expansible pistons; in the contracted position of the pistons the outer surface of each of the ring segments is withdrawn back into the surface of tube 11 and lies in the slot provided in the tubing wall for such segment. The slots, as 219 for segment 19, slot 220 for segment 20, 223 for

segment

23, 224 for segment 24, etc. are each inch wide and, adjacent the pistons, inch deep, and to provide for that the ring segments are less curved than the tube surface, proportionally (about inch) deeper between the pistons. FIGURE 4 is broken away to illustrate

slots

225 and 226, which slots are not actually visible on a central longitudinal section. All the above elements are made of conventional grades of steel which may be conveniently machined. Special steel can be used Where desirable.

In the embodiment shown in FIGURES 9 and 10, the ring segments, as 70, are each held in place by pins, as 71, each fixed to the head, as 104, of an expansible piston, as 17'. Otherwise, each such piston 17 has the same structure as above described for expansible piston as 17. The ring segments, as 70, in this embodiment each extend into a recess, as 170, on the top of the expansion piston so that the top peripheral surface of said ring segment 713 is coplanare or substantially so with the exterior surface of expansion piston head 104. As shown in FIGURE 9, each ring segment is resiliently held in place by a spring, as 171, which is located in a hole, 174, in the ring segment, in which hole the spring and pin, 71, is located for each such ring segment. This embodiment somewhat improves the seal provided by the ring segments in cooperation with the expansible pistons against passage of oil past such seal during the upward movement of the free piston through the oil well tubing as 82.

It is within the scope of the invention that there be a 20% to 40% increase in cross sectional area of the free piston on movement of the expansible pistons as 15, 16, 17, and 18 (with the ring segments attached thereto) from across that flat face.

a smooth fit between each wedge Such piston slots,

9 their contracted to their expanded positions. Even with a device having a 23% increase in area formed generally as in the embodiment above described, the piston above described falls through a 2 inch tubing in a well while it is producing 400 to 500 barrels of oil per day when such fluid contains 300 to 400 cubic feet of gas per 55 gallon barrel, at a suflicient velocity to result in that the free piston made according to this invention as above described reliably opens to its expanded position, as in FIG- URE l hereinabove described, on contact with a stop at the bottom of a 2 inch internal diameter well tubing, rises to a stop at the top of the tubing where it automatically is brought to its contracted form, as in FIGURE 3 above described, and then repeats its travel to the stop at the bottom of the tubing string.

With larger changes in area such as 25% to 33%, pistons made according to the invention herein which operate even when there are higher rates of flows of fluids may be used.

The external bypass free piston as herein above described allows for a greater change in area than can be obtained by the use of internal bypass pistons as well as providing a more complete removal of the parafi'in which otherwise collects on the outside of the piston and inside of tubing 82. It is to be noted that the free piston according to this invention also acts as a scraper to remove parafiin from the walls of the tubing on its upward travel. It should be noted that during the downward travel of the piston through the warmer zones that paraffin will usually melt off that has not already been flushed off. The positive action of radially extending segments and expansible pistons of the free piston device of this invention in removing the parafiin deposits on the interior well tubing wall during its travel upwards in the tubing permits the free piston to freely fall down through the tubing after its upward passage because, during the upward passage, it has removed paraflin accumulations which might otherwise block or impede its downward passage.

While the above disclosure shows the expansible pistons as 15 and 16, and 17 and 18 at right angles to each other, it is, of course, within the scope of my invention that such pistons could be arranged at 60 degrees from each other or some other angle of 90 degrees or less that would permit similarly controlled radial movement of peripheral movable segments such as 19, 20, 21, 22, 23, 24, 25, and 26 above described from their contracted position in and within the exterior surface of the tube, as 11, to expanded position adjacent the well tubing while carrying corresponding movable peripheral segments radially to produce corresponding increases in cross sectional area of the free piston and a smooth fit against such well tubing wall.

It will be understood that modifications can be made in the invention as herein described without departure from the spirit thereof, and therefore, that the description is to be construed as illustrative only; and I do not wish to be limited to the articular details herein set forth,

and my invention is of the full scope of the appended claims.

I claim:

1. A device for lifting fluids through a well pipe including a hollow body, actuating means movable longitudinally within the body and having at least one end thereof protruding from an end of said body, means for releasably holding the actuating means in either of two positions, said actuating means having at least a pair of Wedge elements intermediate its ends, each wedge element being substantially identical and having a face inclined relative to the longitudinal axis of said body, at least a pair of expansible pistons spaced longitudinally in said body and extending normal to its longitudinal axis, each piston being at an angle to the adjacent piston and having two elements longitudinally movable relative to each other and urged away from each other by resilient means located therebetween, the resilient means forcing each piston element into contact with an inclined face of a wedge element whereby each wedge element limits the length of each piston, said body having openings to permit the pistons to extend from said body in a direction normal to its longitudinal axis, and a plurality of longitudinally extending helical segments each attached at either of their ends to one of said pistons, the helical segments cooperating with said pistons to circumscribe said body, said body having recesses for receiving said segments in the contracted position of said pistons, said pistons having outer ends substantially flush with the exterior of said body in said contracted position.

2. A device as set forth in claim 1 wherein the pair of wedge elements includes a pair of superimposed substantially identical plates slidably mounted in the hollow body and movable with the actuating means, each plate having a plurality of divergent guide means, the divergence of the guide means of each plate being in the same amount and direction as measured normal to the longitudinal axis of said body.

3. A device for lifting well fluids through tubing including a hollow body having at least a pair of spaced diametric openings extending at an angle to each other and external recesses extending helically between the ends of adjacent openings, the recesses and openings circumscribing the body, an expansible piston slidably mounted in each opening for radial movement into engagement with the tubing, a ring segment complementary to and slidably mounted in each helical recess for radial movement into engagement with the tubing, the ends of each ring segment being connected to the end portions of adjacent pistons whereby the segments are expansible with the pistons, actuating means slidably mounted in said body for relative longitudinal movement to expand said pistons and ring segments and having at least one end thereof projecting from said body, and means for releasably holding the actuating means in either of two positions, said actuating means having intermediate its ends a wedge portion for each piston, each wedge portion being substantially identical and having a surface inclined with respect to the longitudinal axis of said body, each piston having a pair of sections movable longitudinally relative to each other and resilient means between the sections for urging the same away from each other, the resilient means urging each piston section into contact with an inclined surface of a wedge portion whereby each wedge portion limits the length of each piston.

4. A device as set forth in claim 3 wherein the pair of wedge portions of the actuating means includes at least a pair of superimposed substantially identical plates slidably mounted in the hollow body and movable with said actuating means, each plate having a plurality of divergent guide means, the divergence of the guide means of each plate being in the same amount and direction as measured normal to the longitudinal axis of said body.

5. A device for lifting oil fluids from wells through tubing which comprises:

(a) a hollow tube having a substantial wall thickness,

(bl) a series of wedging elements within the tube, an elongated means within said tube at either end of said series of elements at least one of which means protrudes from an end of said tube, such series of wedging elements being movable by said means as a series within said tube.

(c) means attached to the interior of said hollow tube and releasably contacting the sub-combination comprising the said series of wedging elements and elongated means whereby such sub-combination is releasably held in either of two positions,

(b2) each of said series of wedging elements presenting a face at substantially the same sloped angle to and position with respect to the longitudinal axis of said hollow tube as each of the other wedging elements in series therewith,

(d) a plurality of expansible pistons longitudinally spaced in a series extending along the length of said tube, each such piston being located at least in part within said tubing and extending normal to the longitudinal axis of said hollow tube, each such piston in said series being at an angle to the adjacent piston in series therewith and each said piston comprising two elements longitudinally movable with respect to each other and urged to move away from each other by elastic means located therebetween, said elastic means also forcing each said piston element into contact with a sloped face of a wedging element, whereby each said wedging element limits the length of each said piston,

(e) said hollow tube having orifices therein permitting said pistons to extend from said tube in a direction normal to the axis of said hollow tube, and

(f) a plurality of longitudinally extending helical segment elements, each attached at either of their ends to one of said pistons, said helical segments in cooperation with said pistons, circumscribing said hollow tube, the wall of said hollow tube having recesses therein which receive said helical segments in the contracted position of said pistons, said pistons in said contracted position extending substantially to but not substantially beyond the periphery of said hollow tube.

6. A device as in claim 5 wherein said series of wedging elements further comprises a series of wedging elements comprising a series of substantially identical plates, each of said plates comprising a plurality of diverging guide means, the divergence of all said guide means on each of said plates being in the same amount and direction as measured normal to the longitudinal axis of said tube, said plates each fitting slidably in the interior of said hollow tube, each of said series of plates being contiguous with the nearest plate thereto in said series, and said series of contiguous elements being movable by an elongated rod at either end of said series.

7. A device as in claim 6 wherein the external crosssectional area of said pistons and helical segments in expanded form is between 20% and 40% greater than the maximum external diametral cross-sectional area of said hollow tube alone.

8. A free piston for lifting oil fluids from wells through tubing which comprises (a) a hollow tube having a subtantial wall thickness and a central longitudinal axis,

(b1) a series of contiguous similar wedging element within the tube, an elongated rod within said tube at either end of said series of wedging elements,

(0) means attached to the interior of said hollow tube and releasably contacting the sub-combination comprising the said series of wedging elements and rod whereby such sub-combination is releasably held in either of two positions,

(b2) each of said series of wedging elements presenting a face at substantially the same sloped angle to and position with respect to the longitudinal axis of said hollow tube as each of the other wedging elements in series therewith, said series of contiguous elements being movable by an elongated rod at'either end thereof, each of which elongated rods protrudes from an end of the tube,

(d) a series of piston each located in part within said tubing and with its length normal to the longitudinal axis of said hollow tube, each such piston in said series being at the same angle to the adjacent piston in series therewith, said pistons being in a series extending along the length of said tube and each said piston comprising two portions and an elastic means therebetween, and compressed thereby, said two portions being lengthwise separable from each other and being urged apart lengthwise by said elastic means, each said wedging element comprising a central portion with portions projecting laterally therefrom on each side thereof and extending lengthwise of each 12 7 said wedging element at an angle to the longitudinal axis of said tubing, said lateral projecting portions on each side of said wedging element being sloped oppositely to the slope of the portion on the opposite side of said wedging element, each said piston element contacting a lateral projecting portion of's'aid' wedging element and being held thereby toward the other portion. of said piston element, said elastic means forcing each said piston element into contact with a sloped face of said wedging element, whereby each said wedging element limits the length of each said piston (e) said hollow tube having orifices therein permitting each of said pistons to expand from said tube in a direction normal to the axis of said hollow tube, and

(f) a plurality of longitudinally extending helical segments each movably attached at their ends to one of said pistons and movable radially with the ends of said pistons, said helical segments in cooperation with said pistons circumscribing said hollow tube, and said helical segments extending in a substantially unbroken surface from the periphery of said tube to the periphery of said segments in the expanded position of said pistons, the outside wall of said hollow tube having recesses therein whichreceive entirely said helical segments in the contracted position of said pistons, said pistons in said contacted position extending substantially to but not substantially beyond the periphery of said hollow tube.

9. A device as in claim 8, wherein the external cross sectional area of said pistons and helical segments in expanded form is between 20% and 40% greater than the external maximum diametral cross sectional area of said hollow tube alone.

10. A free piston for lifting fluids from 'wells through a cylindrical tubing which comprises (a) a hollow cylindrical tube having a substantial wall thickness,

(b') a series of contiguous similar wedging elements within the tube, an elongated rod within said tube at either end of said series of wedging elements,

(c) means attached to the interior of said hollow tube and releasably contacting the sub-combination comprising the said series of wedging'elements and rod whereby such sub-combination is releasably held in either of two positions, I 7

(b2) each of said series of wedging elements presenting a face at substantially the same sloped. angle to and position with respect to the longitudinal axis of said hollow tube as each of the other wedging elements in series therewith, said series of wedging elements comprising a series of similar plates, each said plate containing a plurality of diverging guide elements, the divergence of all said elements being in the same direction and amount, said plates each slidably fitting in the'interior of said hollow tube, an elongated rod within said tube at either end of said series of wedging elements, said series 'of contiguous elements being movable by said elongated rod at either end thereof, each of which elongated rods protrudes from an end of the tube, and

(d) a series of similar pistons each located in part within said tube and having a longitudinal axis which extends normal to the longitudinal axis of said hollow tube, each such piston in said series being at right angles to the adjacent piston in series therewith, said pistons being in a series extending along the length of said tube and each said piston comprising two portions and a compressed elastic means therebetween and contacting said portions, said two portions being lengthwise separable from each other and being urged apart lengthwise by said elastic means, each said wedging element comprising a central portion with portions projecting laterally therefrom on each side thereof and extending lengthwise of each said wedging element at an angle to the axis of said tubing, said lateral projecting portions on each side of said wedging element being sloped oppositely to the slope of the portion on the opposite side of said wedging element, each said piston cOntacting a lateral projecting portion of said wedging element and being held thereby toward the other portion of said piston element, said elastic means forcing each said piston element into contact with a sloped face of said wedg-ing element, whereby each said wedging element limits the length of each said piston,

(e) said hollow tube having a series of orifices therein along the length of said tube permitting said pistons to expand outward therethrough from the surface of said tube in a direction normal to the axis of said hollow tube, and

(f) a plurality of longitudinally extending helical segments each movably attached at each of their ends to one of said pistons near an end of said piston and movable radially with such ends of said pistons, each segment being attached to said pistons by a projection on the end of said helical segment, said helical segments in cooperation with said pistons circumscribing said hollow tube and said helical segments extending laterally in a substantially unbroken surface from the periphery of said tube to the lateral periphery of said segments in the expanded position of said pistons, the outside wall of said hollow tube having recesses therein which receive entirely said helical segments in the contracted position of said pistons, said pistons in said contracted position extending substantially to but not substantially beyond the periphery of said hollow tube and the cross sectional area of said piston and helical segments in expanded position being substantially greater than the maximum external diametral cross sectional area of said hollow tube alone.

References Cited by the Examiner UNITED STATES PATENTS 2,674,951 4/1954 Zaba 103-52 2,714,855 8/1955 Brown 10352 2,762,310 9/1956 Eklund 103-52 2,838,005 6/1958 Garrett et a1 103-52 2,937,909 5/1960 Garrett et al. 10352 X References Cited by the Applicant UNITED STATES PATENTS 2,684,633 7/ 1954 Knox.

2,688,928 9/ 1954 Vin-cent.

2,789,645 4/1957 Curnu-tt.

ROBERT M. WALKER, Primary Exa'miner.