US3372756A

US3372756A - Holddown for well tools

Info

Publication number: US3372756A
Application number: US544204A
Authority: US
Inventors: Louis K Muckleroy
Original assignee: US Industries Inc
Current assignee: AXELSON Inc A DE CORP; US Industries Inc
Priority date: 1966-04-21
Filing date: 1966-04-21
Publication date: 1968-03-12
Anticipated expiration: 1985-03-12

Description

March 12, 1968 K. MUCKLEROY 3,372,756

HOLDDOWN FOR WELL TOOLS Filed April 21, 1966 30a 33 3/ J0 3 7 I V/V/f 100/: K Muck/sway INVENTOR.

ATTOR/VEVJ United States Patent Ofiice 3,372,755 Patented Mar. 12, 1968 3,372,756 HOLDDQWN FUR WELL TOOLS Louis K. Muckleroy, Longview, Tern, assignor to US. Industries, inc, a corporation of New York Filed Apr. 21, 1966, S91. No. 54 mm 4 Claims. (Cl. 1662ilfi) This invention relates to holddowns for Well tools of the type used in oil and gas wells, and in particular, to holddowns or anchors of the releasable type that will hold the well tool in position in a string of Well pipe for the desired operation and which will allow the tool to be retrieved from the well pipe in which the tool is located without having to remove the pipe from the well.

Holddowns or anchors are used with a variety of well tools. For example, in sucker rod operated pumps, a standing valve is used to allow oil to flow into the working barrel of the pump, as the pump plunger and traveling valve are moved upwardly by the sucker rods to lift the oil above the plunger toward the surface. The standing valve then closes to hold the oil in the working barrel as the pump plunger and traveling valve move downwardly in the working barrel.

Preferably, such standing valves are retrievable so they can be removed for repair or replacement Without having to pull the well pipe in which they are located. When retrievable, holddown apparatus must be associated with the valves that will hold the valves again-st movement relative to the pipe under normal operating conditions, but which will release the valves for removal from the pipe, when this is desired. Further, when the holddown apparatus and the standing valve are installed in the pipe all of the fluid flowing through the pipe should flow through the standing valve; therefore, it should also act as a packer or seal.

When unseating a standing valve, it is very important for the operator to know how much upward force is going to be required. The well tubing will be filled with the liquid being pumped, if the standing valve has been functioning properly. To unseat the standing valve, this column of fluid will have to be lifted, along with the weight of the sucker rods and pump. Also resisting upward movement of the rods is the force required to release the hold down. Often the total weight of the fluid and the rods is close to the yield strength of the rods. In these cases, the operator needs to know how much force he must exert to unseat the holddown before he runs it into the well.

It is an object of this invention to provide an improved holddown for a well too] which will hold the tool against movement in the well pipe with a predetermined force and which will release the tool for removal when subjected to an upward force in excess of such predetermined force.

It is another object of this invention to provide an improved holddown for a well tool that employs the frictional force developed between two metal members to hold the tool against upward movement in the well pipe.

It is another object of this invention to provide an improved holddown for a well tool in which a metal seal ring is employed along with a seal ring of elastomeric material to provide the seal between the portion of the holddown that is connected in and forms a part of the well pipe, usually called a seating nipple, and the removable portion of the holddown that is connected to the well tool.

It is another object of this invention to provide an improved holddown of simple construction that employs a relatively low cost easily replaced metal ring to create, with the seating nipple, the holding force and to form a portion of the seal between the removable portion of the holddown and the seating nipple.

It is another object of this invention to provide such a holddown that can be adjusted to provide diiferent holding forces by simply changing the friction ring thereon to one of a different size.

It is another object of this invention to provide a holddown that requires substantially the same force to seat the removable portion thereof in its seating nipple as it does to pull this portion therefrom, and one which requires the seating and pulling force to be exerted over a substantial distance to thereby provide identifiable surface indications of when the holddown is seated and when it is released.

In designing holddowns or anchors, it is desirable to provide as large a flow passage through them as possible. Usually, a holddown is required to not only provide a holding force, but to also serve as a packer and seal the annulus between the well pipe containing the seating nipple and the removable portion of the holddown. The holddown seals should be carried by the removable portion of the holddown, so they can be changed, if damaged, each time this portion is pulled. Providing the required space for the seals between the seating nipple bore and the removable portion of the holddown, however, is one reason for a reduced flow passage through the holddown. The use of an O ring type seal would require the least reduction in the holddown bore. 0 rings tend to be washed out of their grooves, however, when being moved through a liquid.

Therefore, it is yet another object of this invention to provide a holddown that employs an O ring seal that is positively held in its groove against the washing action of the fluid through which it is traveling by the member against which it seals, when the removable portion is seated in the seating nipple.

These and other objects, advantages, and features of the invention will be apparent to those skilled in the art from a consideration of this specification and attached drawings.

In which:

FIGURE 1 is a vertical sectional view through a down hole sucker rod operated pump with the preferred embodiment of the holddown of this invention being used to hold the standing valve and working barrel of the pump against movement relative to the well tubing, as the pump plunger and traveling valve reciprocate in the working barrel;

FIGURE 2 is a vertical sectional view on an enlarged scale of the holddown of FIGURE 1; and

FIGURE 3 is a cross sectional view taken along line 3-3 of FIGURE 2.

As stated above, the holddown of this invention can be used with a variety of well tools. It can also be used as an anchor type packer for well tubing. One common use of the holddown is to hold various components of sucker rod operated down hole pumps.

The latter situation is shown in FIGURE 1, where the holddown of this invention, generally indicated by the number 10, is used to hold standing valve 11 and working barrel 12 against movement relative to well tubing 13. The rest of the pump comprises plunger 14, which is equipped with traveling valve 15. The plunger and traveling valve are connected directly to the lower end of sucker rod 16, which is connected to a string of sucker rods (not shown) that extend to the surfaw. Means are provided at the surface to reciprocate the sucker rods to move the plunger and traveling valve up and down in the working barrel.

The operation of this type pump is well known. Standing valve 11 opens as the traveling valve and plunger are moved upwardly by the sucker rods to allow oil to fill into the working barrel. The valve closes, when the traveling valve and plunger are moved downwardly, to force the oil in the working barrel through the traveling valve 3 for movement upwardly therewith on the next upward stroke of the plunger.

Standing valve 11 and traveling valve 15 are of similar construction. Traveling valve 15 has an annular seat 17, which is located between valve body 18 and valve cage 19. The valve cage has inwardly extending protrusions 19a. The one shown having three, spaced 120 apart, that limit the upward travel of ball 20 away from the valve seat. Ball 26, of course, when it engages valve seat 17, prevents the flow of fluid downwardly through the valve. In the embodiment shown, valve cage 19 is held in position by downwardly facing annular shoulder 21 on plunger 14. The plunger, in turn, is connected to traveling valve body 18.

Standing valve 11 also has an annular valve seat 22, which located between valve body 23 and cage 24. This cage also has three inwardly extending protrusions 24:: to limit the upward travel of the valve member, ball 25, away from the valve seat, when the valve is opened by upwardlly flowing liquid well fiuid. Standing valve housing 26 is connected to valve body 23 and holds cage 24 in position through downwardly facing annular shoulder 27. The standing valve housing is connected to working barrel 12.

The upper end of the working barrel is provided with rod guide 28. This rod guide restrains the rod to axial movement along the longitudinal axis of the working barrel. It also serves to transmit the upward force of the sucker rods to the working barrel and standing valve to carry these components of the pump, along with the removable portion of the holddown, to the surface when the sucker rods are pulled from the well tubing. The rod guide is provided with vertical openings (not shown) to allow the passage of the oil lifted by the plunger.

A portion of holddown 10 is installed in well tubing 13 and forms a section thereof. This portion of the holddown is seating nipple .30. The bore of the seating nipple has an upper section 30a of uniform diameter to receive the removable portion of the holddown.

The removable portion of holddown 10 includes holddown body 31, which is integrally connected to standing valve body 23 and extends downwardly therefrom. The holddown body is hollow and has a section 32 of reduced outside diameter. Encircling section 32 is friction ring 33. This friction ring is the portion of the holddown that creates, with the seating nipple, the frictional force that holds the standing valve against upward movement relative to the seating nipple. To obtain this frictional force, the outside diameter of friction ring 33 is larger than the inside diameter of the upper section 30a of the bore through the seating nipple. Thus, to locate the friction ring in the upper section of the bore of the seating nipple in the position shown in the drawings, it must be compressed. When compressed, it exerts a normal force outwardly against the bore of the seating nipple. This creates a frictional force that resists movement of the friction ring relative to the bore of the seating nipple. The amount of this normal force can be varied by changing the size and/ or material of the seating nipple and ring to produce the desired holding force.

The friction ring should provide the desired holding force throughout the time it is located in the bore of the seating nipple. Also preferably, the ring can be inserted and removed from the bore of the seating nipple and then re-inserted without the holddown suffering a loss in holding power. Therefore it should be made of a resilient metal that has suificient ductility to be compressed suiticiently to enter the bore of the seating nipple without suffering permanent deformation and which will exert the the desired normal force against the seating nipple. A material such as lead or babbit obviously will not meet this requirement. Also, the materials for the ring and seating nipple should be compatible in that they will not gall or tend to freeze which would change the force required to remove the ring from the seating nipple.

One combination of materials that has been found to be satisfactory is a low-carbon steel, such as 1015, and a Monel friction ring. With this combination each .010 inch of interference between the ring and the bore of the seating nipple produces about 2,000 lbs. of holding force. This relationship holds up to 10,000 lbs. and appears to be independent of the diameter of the ring. With this combination of materials there is very little galling between the engaging surfaces and the holddown can be seated and unseated several times with little if any reduction in its holding power.

The friction ring also preferably has a length longer than its wall thickness with a relatively fiat outer surface to engage the upper section of the bore of the seating nipple. A lead-in taper should be provided, as shown, to start the ring into the bore of the seating nipple.

Means are provided to limit the relative axial movement of holddown body 31 relative to friction ring 33. In the embodiment shown, annular shoulder 34 limits the upward movement of the holddown body relative to the friction ring. Lower end 35 of standing valve housing 26 limits the downward movement of the holddown body relative to the friction ring.

Means are also provided to limit the distance the holddown body and friction ring can be inserted into the bore of the seating nipple. In the embodiment shown, the bore of the seating nipple is provided with a section 36 of reduced diameter to provide an inclined upwardly facing annular shoulder 37. This shoulder engages the tapered lower end of the holddown body and limits the downward travel of the body in the bore of the seating nipple.

It is one of the features of this invention that a surface indication of the seating of the holddown is obtained. In the embodiment shown, shoulder 37 on the seating nipple is located so that friction ring 33- will move a considerable distance into the bore of the seating nipple before the downward travel of the holddown is stopped. When running the pump then the weight of the rod string will decrease, when the friction ring first engages the seating nipple, until a suificient amount of the weight of the string has been transferred to the friction ring to force it into the seating nipple. The rods are lowered at this reduced weight until further downward travel of the rods is prevented and the weight of the rod string drops off again. These changes in the weight of the string plus the lowering of the string at the reduced weight indicate that the removable portion of the holddown is indeed seated in the seating nipple. Conversely this same surface indication is obtained when the pump is to be pulled from the well tubing. The upward force needed to pull the holddown will be the weight of the rods plus the force required to move the friction ring in the bore of the seating nipple. Also affecting the force required to pull the friction ring out of the seating nipple is the weight of the column of well liquids in the well tubing above the standing vaive. Whatever the total force required it will have to be exerted over the distance required to move the friction ring out of the seating nipple. This will indicate at the surface that the holddown had been in position functioning as desired. When the friction ring clears the end of the seating nipple, of course, there will be a considerable drop in the force required to move the rods upwardly.

In the holddown of this invention, friction ring 33 not only creates, with the seating nipple, the frictional force to hold the standing valve and its associated components in position in the well tubing, but it also forms a metal-to-metal, fluid tight, seal with the seating nipple. Thus, it provides a portion of the seal between the holddown and the seating nipple required to cause all the well fluid to pass through the standing valve. The metalto-metal seal results from the normal force created between the members, when the friction ring is compressed by the seating nipple.

To complete the seal, seal ring 38 is located in groove 39 in the section of reduced diameter on the holddown body. In this embodiment, the seal ring is an O'ring of elastomeric material. The O-ring seals between the inside surface of friction ring 33 and the holddown body. With this arrangement, O-ring 38 is held in groove 39 by the friction ring. Thus, the removable portion of the holddown can be moved through the well tubing and the liquid therein without any danger of the O-ring being washed out of its groove.

The outside diameter of section 32, the section of the holddown body of reduced diameter, is designed to allow friction ring 33 to be compressed sufliciently to enter the seating nipple. It is also designed so that the clearance between section 3-2 and the inside surface of the friction ring, when the friction ring is compressed within the seating nipple, is the proper clearance for O-ring 38.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure.

It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within. the scope of the claims.

As many possible embodiments may be made of the invention Without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. A holddown for well tools comprising, a seating nipple having a longitudinal bore with a section thereof having a uniform diameter throughout its length, a hollow holddown body for connecting to a well tool for insertion into the bore of the seating nipple, means limiting the distance the holddown body can be inserted into the seating nipple bore, a friction ring comprising a continuous annular body of resilient material encircling a section of the holddown body, said ring having a length longer than its wall thickness with a flat outer surface to engage said section of uniform diameter of the bore of the seating nipple, said ring having an outside diameter greater than the diameter of said section and made of a material having non-galling compatibilty with the material of the seating nipple and sufficient ductility and yield strength to be compressed into said section of the seating nipple without suffering permanent deformation whereby said ring is radially compressed in the bore of the seating nipple to form a metal-to-metal fluid tight seal between the ring and the bore of the seating nipple and create a frictional force therebetween, said section of the holddown body upon which the ring is located having a diameter sufliciently less than the inside diameter of the ring to allow the desired compression thereof, means. holding the ring on the body for limited longitudinal movement relative to the body, and a seal ring positioned between the friction ring and the body to provide a seal therebet-ween when the ring is compressed by the bore of the seating nipple whereby said seal ring and the metal-to-metal seal between the friction ring and the seating nipple combine to provide a fluid seal between the seating nipple and the body.

2. The combination of claim 1 in which the seal ring is located in a groove in the section of the body which the annular friction ring encircles.

3. The combination of claim 2 in which the seal ring is of elastomeric material and is of circular cross section.

4. The combination of claim 1 in which the friction ring has a length substantially less than the upper section of the bore of the seating nipple and is located on the holddown body to be moved a substantial distance into the bore of the seating nipple before the travel of the body into the bore is stopped whereby there will be a reduction at the surface in the indicated weight of the sucker rod string when the ring first encounters the seating nipple and again when the body is fully seated in the seating nipple.

References Qited UNITED STATES PATENTS 215,951 5/1879 May "166-105 278,751 6/1883 Shaw 166-105 2,885,968 5/1959 Wagner 166206 FOREIGN PATENTS 1,094,591 12/ 1960 Germany.

JAMES A. LEPPINK, Primary Examiner.

Claims

1. A HOLDDOWN FOR WELL TOOLS COMPRISING, A SEATING NIPPLE HAVING LONGITUDINAL BORE WITH A SECTION THEREOF HAVING A UNIFORM DIAMETER THROUGHOUT ITS LENGTH, A HOLLOW HOLDDOWN BODY FOR CONNECTING TO A WELL TOOL FOR INSERTION INTO THE BORE OF THE SEATING NIPPLE, MEANS LIMITING THE DISTANCE THE HOLDDOWN BODY CAN BE INSERTED INTO THE SEATING NIPPLE BORE, A FRICTION RING COMPRISING A CONTINUOUS ANNULAR BODY, OF RESILIENT MATERIAL ENCIRCLING A SECTION OF THE HOLDDOWN BODY, SAID RING HAVING A LENGTH LONGER THAN ITS WALL THICKNESS WITH A FLAT OUTER SURFACE TO ENGAGE SAID SECTION OF UNIFORM DIAMETER OF THE BORE OF THE SEATING NIPPLE, SAID RING HAVING AN OUTSIDE DIAMETER GREATER THAN THE DIAMETER OF SAID SECTION AND MADE OF A MATERIAL HAVING NON-GALLING COMPATIBILITY WITH THE MATERIAL OF THE SEATING NIPPLE AND SUFFICIENT DUCTILITY AND YIELD STRENGTH TO BE COMPRESSED INTO SAID SECTION OF THE SEATING NIPPLE WITHOUT SUFFERING PERMANENT DEFORMATION WHEREBY SAID RING IS RADIALLY COMPRESSED IN THE BORE OF THE SEATING NIPPLE TO FORM A METAL-TO-METAL FLUID TIGHT SEAL BETWEEN THE RING AND THE BORE OF THE SEATING NIPPLE AND CREATE A FRICTIONAL FORCE THEREBETWEEN, SAID SECTION OF THE HOLDDOWN BODY UPON WHICH THE RING IS LOCATED HAVING A DIAMETER SUFFICCIENTLY LESS THAN THE INSIDE DIAMETER OF THE RING TO ALLOW THE DESIRED COMPRESSION THEREOF, MEANS HOLDING THE RING ON THE BODY FOR LIMITED LONGITUDINAL MOVEMENT RELATIVE TO THE BODY, AND A SEAL RING POSITIONED BETWEEN THE FRICTION RING AND THE BODY TO PROVIDE A SEAL THEREBETWEEN WHEN THE RING IS COMPRESSED BY THE BORE OF THE SEATING NIPPLE WHEREBY SAID SEAL RING AND THE METAL-TO-METAL SEAL BETWEEN THE FRICTION RING AND THE SEATING NIPPLE COMBINE TO PROVIDE A FLUID SEAL BETWEEN THE SEATING NIPPLE AND THE BODY.