US2350973A - Pressure-actuated tubing anchor - Google Patents

Description

June 1944- E. c. BRUMLEU ET AL 2,350,973

PRES SURE -ACTUATED TUBING ANCHOR Filed Oct. so, 1943 2 Sheets-Sheet 1 Fig! Invenfors: WaH'on E. G'nlberf Edward C. Brumlcu 59 war Ammmm Patented June 6, 1944 PRESSURE-ACTI ATED TUBING ANCHOR- Edward 0. Brumlen and Walton E. Gilbert, Ins Angeles, Calif.: said Gilbert allll'nor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application October 30, 1943, Serial No. 508,364

11 Claims. (Cl. 103-219) The present invention relates to improved apparatus for use in oil wells which are being produced by rod-actuated well pumps, and pertains more particularly to an apparatus for anchoring tubing or pipe strings in such wells. This application is a continuation-in-part of our application Serial No. 476,124, filed February 16, 1943.

It has long been recognized that the tubing through which a well is being pumped should be anchored near its lower end in addition to being supported at the top, since the cyclical change in fluid load due to the pumping action would otherwise result in an appreciable motion of the lower end of the tubing. Thus operators frequently resort to anchoring the tubing near its lower end in order to eliminate external wear of tubing joints and collars, and to improve pumping efllciency by preventing the partial loss of pump stroke which attends tubing motion.

In the past, this has been accomplished by setting the tubing on a device commonly known as a tubing anchor, which is usually set by putting at least part of the tubing in compression. This conventional method of anchoring tubing has been unsatisfactory in that it depends upon the humanelement to judge the amount of compression in which the pipe is set. Also, the conventional method of setting anchors in compression very frequently results in severe wear of rods and internal wear of tubing by abrasive rubbing in the reverse curves of the section of the tubing under compression, which rubbin action promotes working of tubing joints and results in a concentration of leakage troubles in the compressed tubing section. Devices have likewise been made which would allow the anchoring of tubing in tension, but these devices have again depended on the human element in putting the correct amount of tension in the tubing.

Also, it is not practicable under the best circumstances to set the usual type of tubing anchor without an unnecessary extra length of tubing in compression. In practice, the usual type anchor is set in compression before the rods are installed in the well. Consequently the compression load on the anchor, and the corresponding length of tubing in compression above the anchor, are both materially increased when pumping starts and the tubing is filled with fluid to the surface. Actually, the differential load, which must be supported by the anchor to prevent deleterious reciprocating motion of the tubing, is only a fraction of the total fluid load, being that part of the latter approximately defined by the ratio of the pump-plunger area divided bythe inside area of the tubing. As a result, both the compression load imposed in setting the conventional anchor and the part of thefluid load steadily imposed on the anchor (which is approximately the total fluid load multiplied by one minus the ratio of the pump plunger area over the inside tubing area) represents extra compressive loading which is not needed to prevent motion of the lower end of the tubing but which is normally applied in setting conventional tubing anchors.

It is, therefore, an object of this invention to eliminate compressive loading entirely by running the tool in tension or, alternatively, by'running the tool in compression so that it sets automatically and assumes only a predetermined part of the fluid load.

It is also an object of this invention to provide means of performing the useful functions priorly performed by conventional compression-type tubing anchors and at the same time to obviate the deleterious and harmful effects above mentioned which are consequent upon use of compressiontype anchors of usual types.

It is also an object of this invention to provide an improved positively controlled tubing anchor adapted to be set in a well or removed therefrom by the application of fluid or hydraulic pressure without the necessity of rotating the tubing, thus eliminating the cause of many accidents incidental to use of tubing anchors in the past.

More specifically, it is an object of this invention to provide a tubing anchor which can be set in a well by actuating a gripping mechanism by means of the differential hydraulic pressure existing between the pressure head of the liquid column raised in the tubing by the pump, and the pressure head of the liquid standing in the well.

Another important object of this invention is to provide an improved tubing anchoring device, which, when used in tension, automatically adjusts its depth location in response to any increase in pumping loads or increase in the tem-, perature of the tubing, and thus eliminates the' human element in its setting, and which, when used in compression, is automatically set by hydraulic pressure without any need of length adjustment of the tubing at the well head, and effeotively prevents tubing motion with considerably less length of tubing in compression than the minimum necessary in setting conventional types of anchors.

A still further object of this invention is to provide a device of the character described which is safe in operation, simple in construction, economical to build and operate, and which insures reduction of physical depreciation of the tubing and rods and the maintenance of favorable pumpstroke efllciencies.

With the above and other objects and advantages in view, theinvention has particular relation to the arrangement and construction of parts; an example of which. is described in this specification and illustrated in the accompanying drawings, wherein:

Figure l is a view, partly in elevation and partly in section,.of a preferred embodiment of the tubing anchor .01 the present invention.

Figure 2 is a cross-section taken along the line -2 of Figure 1. y

Figure 3 is a cross-section taken along the line 3-3 of Figure 1.

Figures 4 and 5 give a diagrammatic view, partly in elevation and partly in section, of the tubing anchor in position in the bore of a well, together with other equipment pertinent thereto.

Briefly, the tubing anchor of the present in-' vention is pressure-actuated and comprises a tubular mandrel connected into the tubing string as a part thereof, a slidable plunger sleeve surrounding the upper portion of said mandrel, said mandrel and piston sleeve defining a pressure chamber therebetween, a port or ports providing communication between the bore of said mandrel and said pressure chamber, resilient means tending to hold the piston sleeve at or near the upper limit of its travel, a taper element on said mandrel, well-gripping elements or slips adapted to be slidably supported from said sleeve and to be guided into an operative position in engagement with the well casing by said taper element, and resilient connecting means between said gripping means and said piston sleeve, whereby said gripping means are maintained in operative position even when the tubing string is subjected to an elongating stress.

The device may be used with the tubing anchored either in tension or compression. Since words like "upwar and downward are useful in describing the action and parts of such a device, and as a matter of maintaining clarity, the device is depicted and described as it is used with tension loading. The changes consequent upon using the device for compressive loading will be explained hereinbelow.

Referring to Figs. 1 to 3 of the drawings. the tubing anchor includes a tubular mandrel I having externally threaded end portions I I and H. A downwardly diverging tapered member I 3 is fitted over the lower end of the tubular member l3 and is securely held in place against a projecting shoulder M on said mandrel II! by a threaded collar l5. 'I'his'collar 15 may be provided with a lateral port or ports I6 fitted with a closure disc or discs il held in place by means of a bushing l3 for a subsequently described purpose. The gripping elements or slips 23, having toothed or serrated faces 2|, areheld in slidable engagement with the tapered faces of the tapered member l3 by means of keys 22 on slips 23 and keyways 23 in tapered member l3. By-pass spaces 24 are provided on the tapered member I3 to allow maximum practicable cross-sectional areas for passage of fluid up the annular space.

Threadably attached to the upper threaded end portion ll of the tubular mandrel i3 is a tubular member 33 of a slightly larger outside diameter thantubular mandrel l3. Tubular member 33 is provided with an external annular groove 3| adapted to receive a packing element or elements 32. The upper end 33 of the member 33 is threaded with a left hand thread for connection to a substitute 34 which in turn is provided at its upper end with a threaded portion 35 for 'connection to a tubing string.

A tubular sleeve 43 has a thickened lower portion ll fitting slidably about the mandrel l3, and

"an upper portion 42 of larger inside diameter fitting slidably about tubular member 33. The upward travel oi. sleeve 43 is limited by contact of portion 4| with enlarged tubular member 33. An internal annular groove 43 is provided in the thickened lower portion ll of sleeve 43 and carries a sealing element or elements 44. By this arrangement, the tubular sleeve 43, mandrel i3 4 and tubular member 33 form a pressure chamber 46 therebetween. A port or ports 4'! extends laterally through the mandrel l3 and provides fluid communications between the bore of mandrel l3 and the pressure-chamber 46. Resilient means, preferably a coil spring 53, surrounding said mandrel l3 and acting at one end against the upper transverse face of the tapered member l3 and at the other end against the lower transverse face of the sleeve 33 tends to hold the sleeve 43 at or near the upper limit of its travel. With the application of fluid pressure through the lateral port 31 into the pressure chamber 46, the sleeve 43 acts as a piston and is forced downward compressing coil spring 53 as will subsequently be described. A fishing neck 5| may be provided on the upper end of the sleeve 43. Rotation of the sleeve is prevented by means of a key lug 52 on the tubular member 33 riding in a vertical key slot 53 in the sleeve 43.

The slips 23 are provided with upwardly-extending actuating arm 55 which are resiliently connected to the pressure-actuated sleeve 43 by suitable means. For example, in a preferred arrangement, the upper end of the slip actuating arms 55 is enlarged in a circumferential direction as at 56, as shown in Figures 1 and 2. The external part of the thickened lower portion ll of the sleeve 43 is formed with a radially projecting annular portion 53 having vertical slots 53 radially deeper than the thickness of the slip arms 55 and having a relatively shallow annular groove 63 in the lower portion. The slots 59 are just wide enough to receive the slip arms' 55, but too small to allow the circumferentially enlarged upper end 56 of said arms 55 to pass therethrough. The arms 55 are positioned in these annulariy-spaced slots 59 with the enlarged-ends 56 of the arms 55 resting on the upper transverse face SI of the outwardly-projecting portion 33 of the sleeve 43. Also resting on said face GI and surrounding the enlarged upper ends 56 of the slip arms 55 is a retaining ring 65. Sprung into place in the groove 63 is a split resilient metal retaining ring 66. Thus, the slip arms 55 are slidably connected for a limited vertical travel to the sleeve 43. Surmounting the upper ends 56 of the slip arms 55 and the upper retaining ring 65 and fitting slidably around the pressure-actuated sleeve 43 is a sleeve 73. Also, surrounding the pressure-actuated sleeve 43 and compressed between the sleeve 13 and a retaining nut ll threadedly attached about the upper portion of the pressure-actuated sleeve 43 is a relatively light coil spring 12, which tends to hold the sleeve 13 and the slip arms 55 therebelow at the lower limit of their vertical travel. This connecting arrangement between the slip arms 55 and the pressureactuated sleeve 43 provides means for automatically adjusting the force acting on the slip arms 53. Such adjusting means or resilient connection is necessary, since the sleeve 48 may be forced downward somewhat beyond the point at which .the slips 28 fully engage the casing and since the slip arms 88 are preferably not designed to withstand large compressive loads.

In operation -(see Figures 4 and 5), the tubing anchor is lowered into a well on the lower end of the tubing string 88. A tubing catcher 8| may be attached below the tubing anchor so as to provide means for catching the tubing string 88 in case it should-be inadvertently dropped while lowering or raising. A pump 82 with its standing Valve 88- and a travelling valve 84 is then lowered into the well on the lower end of a sucker rod string 88. Power is transmitted tothe pump 82 through the reciprocating motion of the rod string 85, and the pump 82 raises well fluids to the surface. A packing gland 8'! surrounds the rod string 85 at the well-head to prevent leakage of well fluids thereby. A flow line 88 is provided to conduct the well fluids to storage in the conventional manner. When the pump 82 is started, well fluids are pumped up into the tubing above the pump 82. Each successive pumping stroke of the pump 82 causes the well fluids to rise higher above the pump 82. When the fluid in the tubing has risen to a point where its differential fluid pressure over the annular area at the lower end of the pressure chamber 88 exceeds the compression in spring 58, the movable sleeve 88, slip arms 58 and slips 28 all move downward until the slips 28 engage the walls of the casing 88, as shown in Figure 4. After the slips 28 have engaged the casing 88, the pressure-actuated sleeve 48 continues to move downward to its lower position and the slip arms 55 acting in an upward direction against the sleeve 18 compress the relatively light spring 1-2. Thus, all the compressive load except that due to compression spring I2 is eliminated from slip arms 55. As the fluid head in the tubing 88 rises and the temperature of the tubing increases, the tubing will tend to elongate. However, the compression in spring I2 transmitted continuously against the slips 28 keeps them forced down and outward against the casing 98 at all times permitting the tubing anchor to adjust itself downward to an operative position in response to any elongation of the tubing 88.

When it is necessary to remove the tubing 88 from the well, the pump 82 and the standing valve 83 is unseated and removed from the well by lifting the rod string 85. This allows the fluid in the tubing 88 above the pump 82 to fall back down the tubing 88 and into the annular space 9| between the tubing 88 and the casing 98 until such time as the levels and fluid pressures in the tubing 88 and annular space 9| become equalized. This equalization of pressures removes the downward force held against the spring 58 so that the spring 88 moves the sleeve 48 upward until its outwardly projecting portion 58 contacts the radially enlarged upper ends 58 of the slip'arms 55. Since the teeth 2| of slip 28 have bitten into the walls, it is then only necessary to lower the tubing 88 a few inches at the level of the tubing anchor, thus lowering the tapered member I8 and permitting radial contraction of the slips 28, whereby the tubing anchor is freed from its hold on the casing 88. The spring 58 is then free to force the sleeve 48 back to the upper limit of its travel with the slips 28 fully retracted radially.

To facilitate release of the tubing anchor, a special arrangement of surface connections at the well-head such as shown in Figure 4 is preferred. The handling procedure at the well-head is as follows: The sucker rod packing gland 81 is removed, the pump 82, standing valve 88 and rod string 85 are withdrawn from the well, a conventional lifting nipple is then inserted and attached to the internal threads 88 at the upper end of the substitute 84- which connects the tubing 88 to'the supporting flange 85. The flange bolts 96 are removed, allowing the flange 85 to be unscrewed from substitute 88 and to be lifted clear of its packing ring 81. By using a lifting nipple of appropriate length, the tubing 88 is then free to be lowered enough to provide a few inches (for example, 5 inches) of downward movement of the tubular mandrel l8 of the tubing anchor. This is sufilcient to free the gripping engagement of the slips 28 on the casing 98 as previously described.

In case the pump 82 has become, for any reason, stuck or sanded to such an extent that it cannot be pulled loose so as to allow equalization of pressure in thetubing with that in the annular space 8|, discs I! (Figure 1), which are formed of a metal of predetermined bursting strength, can be blown out by the addition of excess pressure in the tubing 88 at the top of the well. The bursting of the discs I! will allow the fluid pressures in tubing 88 and in the annular space 8| to equalize, thereby allowing the tubing anchor to be released by a short downward movement of the tubing 88 and the tubular mandrel l8. If under extraordinary circumstances both of these procedures for release of the tubing anchor should prove ineffective, right hand rotation of the tubing 88 will cause the unscrewing of the left hand thread 33 which connects the substitute 38 to the upper tubular member 38. The tubing 88 may then be removed and a suitable fishing tool run in to grip the fishing neck 5|, whereby removal of the tubing anchor and appended tubing is insured.

It will be seen that the tubing anchor of the present invention is simple in structure and operation and eliminates complicated operations in setting the tubing anchor at the proper position in the well. There is no need for rotating the tubing 88 in the ordinary procedure for setting or releasing the present tubing anchor. Thus an operation which has proven hazardous in the setting and releasing of tubing anchors is eliminated. Since the tubing anchor of the present invention automatically adjusts itself ,to the varying conditions existing in each individual well, there can be no error in the amount of tension carried in the tubing string 88.

It is desired to make particular mention of the fact that the device may be run with tubing in compression rather than in tension, as above described. When used in this alternative manner, the anchor is connected in a position upside down to that described. It may be released by collapse of the hydraulic pressure or may be pulled out of the hole without releasing, if necessary, because the spring 12 is light enough to permit relative motion between slips "and conical member l3 without iniuring slip arms 55. Further, when run in this manner, the flshing neck 5|, the discs l1, and the left-hand thread 33 may be, if desired, eliminated as unnecessary. Also, when the tool is run in compression, no special arrangement of surface connections, such as shown in Fig. 4, is necessary.

Although the present invention has been described in relation to a particular embodiment well, a string of tubing, a pump at the lower end thereof ior raising a column oi liquid in said tubing, a plunger sleeve surrounding said tubfining therebetween a pressure chamber, port means in said tubing, whereby said plunger sleeve is moved by applying thereto the hydrostatic pressure or the liquid raised by the pump within the tubing, spring means adapted to oppose said motion, gripping means attached to said sleeve, a taper element carried by said tubing, said gripping means being adapted to be guided by said taper element into engagement with the well casing upon a pressure-responsive motion of said sleeve, and out of engagement therewith upon a spring-responsive motion of said sleeve.

2. In awell-pumping installation for a cased well, a string of tubing, a pump at the lower end thereof ior raising a column of liquid in said tubing, a plunger sleeve slidably surrounding said tubing above said pump, spring means adapted to ur e said plunger sleeve in one axial direction, means .comprisinglateral ports in said tubing for moving said plunger sleeve in the opposite axial direction against the action of said spring by applying thereto the hydrostatic pressure of th liquid raised by the pump within the tubing, gripping means attached to said sleeve, a taper element carried by said tubing, said gripping means being adapted to be guided by said taper element into engagement with the well cas ing upon a motion of said sleeve in said second direction, and out of engagement therewith upon a motion of said sleeve in said first direction.

3. In a well-pumping installation for a cased well, a string of tubing, a pump at the lower end thereof for raising a column of liquid in said tubing, a plunger sleeve slidably surrounding said tubing above said pump, spring means adapted to urge said plunger sleeve in one axial direction, means comprising lateral ports in said tubing for moving said plunger sleeve in the opposite axial direction against the, action of said spring by in above the pump, said tubing and sleeve desaid sleeve, a taper element carried by said tubing, said gripping means being adapted to be guided by said taper element into engagement with the well casing upon a pressure-responsive motion ofsaid sleeve, and out 01' engagement therewith upon a spring-responsive motion of said sleeve.

5. In a well-pumping installation for a cased well, a string of tubing, a pump atthelower end thereof for raising a column or liquid in said tubing. a plunger sleeve slidably surrounding said tubing above saidpump, an annular pressure chamber defined between the tubing and said sleeve, spring means adapted to urge said plunger sleeve in one, axial direction, means comprisns ports between the inside oi the tubing and said chamber for. moving said plunger sleeve in the opposite axial direction against the action of said spring by applying the hydrostatic pressure of the liquid raised by the pump within the tubing to said chamber, gripping means slidably supported by said sleeve, a taper element carried b said tubing, said gripping means being guided by said taper element into engagement with the well casing upon a pressure-responsive motion of said sleeve, and second spring means adapted to move said gripping means with regard to said sleeve in the direction of the pressure-responsive motion of said sleeve.

6. In a well-pumping installation comprising a cased well and a pump lowered thereinto at the end of a tubing string, an anchor for said tubing, said anchor comprising a tubular mandrel adapted to be connected into said tubing string above the pump, a plunger sleeve slidably surrounding said mandrel, an annular pressure chamber defined between said mandrel and said sleeve, means comprising lateral ports in said mandrel in communication between the inside of the string and said chamber for moving said plunger sleeve by applying the hydrostatic pressure of the liquid raised by the pump to said chamber, spring mean adapted to oppose said motion, gripping means attached to said sleeve. and a taper element attached to said mandrel. said taper element being adapted to guide said gripping means into engagement with the well app ying thereto the hydrostatic pressure of the I liquid raised by the pump within the tubing, gripping means slidably supported by said sleeve, a taper element carried by said tubing, said gripping means being guided by said taper element into engagement with the well casing upon a pressure-responsive motion of said sleeve, and second spring means adapted to move said gripping means with regard to said sleeve in the direction of the pressure-responsive motion of said sleeve.

4. In a well-pumping installation for a cased well, a string-of tubing, a pump at the lower end thereof for raising a column of liquid in said tubing, a plunger sleeve slidably surrounding said tubing above said pump, an annular pressure chamber defined between the tubing and said sleeve, spring means adapted to urge said plunger sleeve in one axial direction, means comprisms Po s between the inside 01' the tubing and said chamber for moving said plunger sleeve in the opposite axial direction against the action of said spring by applying the hydrostatic pressure of the liquid raised by the pump within the tubing to said chamber, gripping means attached to 15 casing upon a pressure-responsive motion of said sleeve, and out 0! engagement therewith upon a spring-responsive motion of said sleeve.

7. In a well-pumping installation comprising a cased well and a pump lowered-thereintoat the end of a tubing string, an anchor for said tubing, said anchor comprising a tubular mandrel member adapted to be connected into said tubing string above the pump, a plunger sleeve slidably surrounding said mandrel, an annular pressure chamber defined between said mandrel and said sleeve, spring means adapted to urge said sleeve in one axial direction, means comprising ports in said mandrel in communication between the inside of the string and said chamber for moving said plunger sleeve in the opposite axiall-direction against the action of said spring by applying the hydrostatic pressure of the liquid raised by the pump to said chamber, gripping means slidably attached to said sleeve, a taper element attached to said mandrel, said taper element being adapted to guide said gripping means into engagement with the well casing upon a pressure-responsive motion of said sleeve, and second spring means adapted to move said gripping means with regard to said sleeve in the direction. oi the pressureresponsive motion of said sleeve.

8. A pressure-actuated tubing anchor comprisan operative position upon a pressure-responsive ing a tubular mandrel adapted to be connected into a tubing string, a plunger sleeve member slidably surrounding said mandrel, an annular pressure chamber defined between said mandrel and said plunger sleeve, spring means urging said plunger sleeve in one axial direction, means comprising ports in communication between the inside of said tubular mandrel and said chamber for moving said plunger sleeve in the opposite axial direction against the action of said spring by applying to said chamber the fluid pressure within said mandrel, gripping means slidably attached to said sleeve, a taper element carried by said mandrel, said gripping means being adapted to be guided by said taper element into an operative position upon pressure-responsive motion of said sleeve and into an inoperative position upon a spring-responsive motion of said sleeve.

9. A pressure-actuated tubing anchor comprising a tubular mandrel adapted to be connected into a tubing string, a plunger sleeve member slidably surrounding said mandrel, an annular pressure chamber defined between said mandrel and said plunger sleeve, spring means urging said plunger sleeve in one axial direction, means comprising ports in communication between the inside of said tubular mandrel and said chamber for moving said plunger sleeve in the opposite axial direction against the action of said spring by applying to said chamber the fluid pressure within said mandrel, gripping means slidably attached to said sleeve, a taper element carried by said mandrel said grippi means being adapted to be guided by said taper element into motion of said sleeve and into an, inoperative position upon a spring-responsive motion of said sleeve, and second spring means adapted to move said gripping means with regard to said plunger sleeve, in the direction of the pressure-responsive motion of said sleeve.

10. In the apparatus of claim 6, second lateral port means in said mandrel in communication between the inside of said string and the well, and a; frangible closure element for said port means adapted to be broken by the application of excess fluid pressure to the tubing string from the surface, whereby the liquid column within the tubing is drained into the well through said second port means, and the hydrostatic pressures within and without the tubing are equalized.

11. A pressure-actuated tubing anchor comprising a tubular mandrel, a slidable sleeve piston surrounding said mandrel at one end thereof,

, said mandrel and sleeve piston defining a pressure chamber therebetween, ports in communication between the bore of said mandrel and said pressure chamber, resilient means tending to hold said mandrel and sleeve piston in a position whereat the chamber defined therebetween has a minimum volume, a downwardly-diverging taper on the lower end of said mandrel, gripping elements adapted to move slidably on said taper, actuating arms attachedto said gripping elements, and resilient? connecting means between said actuating arms and said sleeve piston. I

EDWARD C. BRUMLE'U. WALTON E. GIHBERT.

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