US3385372A - Flow control float collar - Google Patents

Description

May 28, 1968 L. c. KNOX L I L L v FLOW CN'KIROL FLOAT COLLAR Filed Jan. ll, 1967 VIIIIII' .:Oyo c AfA/0x,

BY .ZM Pm @M114 JMA ML ATTORNEYS United States Patent O 3,385,372 FLOW CONTROL FLOAT COLLAR Lloyd C. Knox, Duncan, Okla., assignor to Halliburton Company, Duncan, Okla., a corporation of Delaware Filed Jan. 11, 1967, Ser. No. 608,632 Claims. (Cl. 166-225) ABSTRACT OF THE DISCLOSURE A valve for limiting the rate of fill-up as a casing string is lowered in a bore hole. The valve is converted to a back pressure valve by pumping fluid down the casing to break a frangible link within the valve.

Background of the invention This invention relates to well apparatus, and more particularly to oat collars for use in cementing operations.

In running a casing string in a bore hole, it is necessary to provide a valve for controlling the rate of flow of uid from the bore hole into the casing. If the fluid is not controlled as it enters the bottom ofthe casing, the fluid pressure in the well may be sufficient to cause the fluid to blow out through the top of the casing. On the other hand, it is, necessary to fill the casing gradually as it is lowered to compensate for the head of fluid on the outside of the casing. Various self-till float valves have been utilized for limiting the rate of flow of uid into the casing, as it is being lowered into the bore hole.

After the casing has reached the desired depth, it is cemented in place by conducting cement down the casing and out through the bottom of the casing, where it ows upwardly through the annular space between the casing and the bore hole wall. Accordingly, it is necessary to provide a valve which will resist the back pressure of the cement slurry in the annulus. The -back pressure valve, however, should prevent ow of the slurry back into the casing, While the self-fill float valve allows a restricted flow into the casing. Since these valves operate under different conditions and during different portions of the casing cementing process, it has been proposed to combine these valves in a single unit and to render the valves operative by various means. It is important that the valves operate effectively and reliably to ensure a successful cernenting operation.

Accordingly, it is an object of this invention to provide an improved flow control valve for casing strings.

Itis a further object of this invention to provide a combined self-fill oat and -back pressure valve that operates effectively for controlling the rate of lling of the casing.

Another object of this invention is to provide a combined float and back pressure valve that may be easily tripped with a conventional rig pump at any time while running the casing in the Well.

Summary of the invention These objects are accomplished in accordance with a preferred embodiment of the inve-ntion 'by a collar having a tubular body with a valve guide in the body. A valve seat is formed in the body above the valve guide. A- movable valve element is mounted in the valve guide in position to move upwardly into engagement with the valve seat and is spring biased toward the valve seat. A fluid reaction surface is mounted on the valve stem below the valve element. The uid reaction surface is biased downwardly by a spring that applies a greater axial force to the valve stem than does the spring biasing the valve element. The uid reaction surface is arranged to exert an upwardly directed force on the valve stem in response to the flow of fluid upwardly through the casing. Thus, the

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lreaction surface restricts or limits the rate of ilow upwardly by displacing the rst valve element against the Valve seat. There is a frangible link joining the reaction surface to the valve stem and upon pumping fluid down the casing at a predetermined rate, the force of the fluid on the reaction surface breaks the frangible link and causes the reaction surface to be displaced downward and thereby rendered ineffective. After the frangible link is broken, the valve element is released and its spring urges the valve element against the valve seat. Therefore, the collar is converted to a back pressure valve.

Description of the drawings lline 4 4 in FIG. 3; and

FIG. 5 is an enlarged cross sectional view of the lower portion of the valve stem.

Description of the preferred embodiment Referring to FIG. l, the valve includes atubular body 2 having an internal threaded portion at the upper end for receiving and being threadedly secured to a joint of casing pipe 4. The lower end -of thetubular body 2 is also threaded .for connection to alower pipe joint 6. A valve housing 8 is secured in thebody 2 by cast concrete 1t). Acentral passage 12 is formed through theconcrete 10 and communicates with an opening in the housing 8. The lower portion of the housing 8 includes avalve guide 14. As shown in FIG. 4, thevalve guide 14 is supported at the -center of the housing 8 by a plurality ofradial ribs 16. The space between theribs 16 permits Huid to pass upwardly and downwardly through the housing 8. A tube 18 is secured to the lower end of the housing 8 and is rigidly held in position by theconcrete 10 which surrounds the tube.

Avalve stem 20 is mounted for longitudinal movement in thevalve stern guide 14 and avalve element 22 is rigidly secured to the upper end of the stem 2.0. Thevalve element 22 is preferably formed of a resilient, elastomeric material, which effectively seals against the flow of fluid upwardly when the valve element is in engagement with a valve seat 24 formed in the interior of the housing 8. The valve element is urged toward the valve seat 24 by ahelical spring 26 that is compressed between thevalve stem guide 14 and thevalve element 22.

As shown in FIG. 5, the valve stern 2G may be made up of several components which form a bearing portion 28 which has a cylindrical surface of substantially constant diameter to cooperate with thevalve guide 14. At the lower end of the bearing portion 28, aradial shoulder 30 is formed in thestem 20. Anaxial extension 32 projects downwardly from theshoulder 30 and anut 34 is threaded on the lower end of theextension 32. Asleeve 36 is mounted in telescoping relation on theextension 32 and the upper end of thesleeve 36 abuts against theshoulder 30. A shear pin 38 extends through aligned holes in thesleeve 36 and in theextension 32 in order to restrict temporarily axial movement of the sleeve away from theshoulder 30. Thesleeve 36 also has an internal shoulder 40 which projects inwardly from the interior of thesleeve 36.

The lower end of thesleeve 36 is in the form of anorifice plate 42. As shown in FIG. 2, theorifice plate 42 has a plurality of radial webs which extend outwardly in close proximity to the interior surface of the tube 18. An orifice washer 44 is mounted over theorifice plate 42, and is preferably formed of a flexible resilient material, such as rubber. The washer 44 is held in place on theorifice plate 42 by aspring guide 46. As fluid flows upwardly between the washer 44 and the tube 18, the peripheral edge f the washer 44 is deflected upwardly, thereby enlarging the llow area between the tube 18 and washer. A coil spring 48 urges thespring guide 46 toward theorifice plate 42, and thereby clamping the washer 44 against theplate 42. The upper end of the spring 48 bears against the lower side of thevalve guide 14. Preferably, the spring 48 has a higher spring rate than that of thespring 26, so that the stem is normally displaced downwardly to the position shown in FIG. 1.

The shear pin 38 is designed to break when fluid is pumped down the casing at a predetermined rate. The spring rates of thesprings 26 and 48 are selected in relation to the sizes of the tube 18, theorifice plate 42 and the washer 44. The normal resultant force on thestem 20 when there is no fluid llow through thevalve body 2, causes theplate 42 and thevalve element 22 to be posi tioned as shown in FIG. 1. When fluid flows upwardly through thebody 2, at a rate above the maximum rate desired for filling the casing, the force of the fluid on theorifice plate 42 and on the washer 44 exceeds the biasing force of the spring 48 and thevalve element 22 is displaced upwardly against the seat 24.

In operation, thetubular body 2 is made up in a casing string, `as shown in FIG. 1. As the casing string is lowered in the hole, fluid from the bore hole enters thebody 2 through the openings in theorifice plate 42. The fluid pressure acting on the lower surface of the washer 44 tends to deflect the peripheral edge of the washer upwardly, thus increasing the effective cross sectional area of the flow path between the tube 18 and the washer 44. The fluid pressure differential across theorifice plate 42 and the washer 44, due to this flow of fluid upwardly through the tube 18, imposes an axial force on thevalve stem 20. In normal operation, the rate of flow of fluid upwardly through tube 18 Varies and accordingly theorifice plate 42 tends to move up and down in the tube 18. However, since the tube 18 has a uniform internal diameter, the force on thestem 20 due to fluid flow is not affected by the longitudinal position of theorifice plate 42 relative to the tube 18. When the rate of flow is sufficiently high to overcome the force of the spring 48, thevalve element 22 moves upwardly into engagement with the valve seat 24. Thus, theorifice plate 42 and the washer 44 limit the rate at which fluid flows upwardly through thevalve body 2.

Thevalve element 22 engages the valve seat 24 when the llow rate is sufficiently high and remains in engagement with the valve seat 24 as long as a substantial pressure differential exists between the interior of the housing 8 and thepassage 12 above thevalve element 22. This condition may occur when the casing is lowered in the bore hole too fast. In that event, the valve may be reopened by filling the casing from the surface and equalizing the pressure above and below thevalve element 22.

When the casing string has been lowered t0 the desired depth, the tool may be converted to a float collar by pumping fluid down the easing and through the body 2.The pressure of the fluid on the upper side of the washer 44 maintains the washer flat against theorifice plate 42. Since the peripheral edge of the washer 44 is close to the tube 18 when the washer is flat, the flow of fluid downwardly through the tube 18 is restricted. When a predetermined pressure differential is established across the washer 44, sufficient axial force is applied to thesleeve 36 to shear the pin 38. The action of the downwardly flowing fluid on the washer 44 and the force of the spring 48 displace thesleeve 36 downwardly until the internal shoulder 40 engages the upper end of thenut 34. As soon as the pin 38 has sheared, the upper portion of thestem 20 is released and thespring 26 displaees thevalve element 22 upwardly into engagement with the valve seat 24. Theorifice plate 42, the washer 44, and the spring 48 no longer control the position of thevalve element 22, and therefore, the valve functions as a back pressure valve, biased toward a closed position by thespring 26.

The tool of this invention performs effectively as a flow rate control valve while the casing is being lowered in the bore hole, and may be readily converted to a back pressure valve merely by pumping fluid down the casing at a sufficiently great rate to break the shear pin 38. Since thesleeve 36 is retained on the lower end of theextension 32, there are no loose pieces which might interfere with the operation of the valve, as there would be if the lower portion of the valve completely separated upon breaking of the frangible link 38. Also, the arrangement of the tube 1S with respect t0 theorifice plate 42, and washer 44 provides an approximately uniform response to upward fluid flow, regardless of the longitudinal position of the orifice plate in the tube 18.

While this invention has been illustrated and described in one embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.

I claim:

1. Valve apparatus for controlling fluid flow through a pipe string in a well comprising:

a tubular body adapted for connection in a pipe string, means in said tubular body forming a valve guide, means forming a valve seat in said body, said valve seat being spaced upwardly from said valve guide,

a valve element movable upwardly into engagement with said valve seat, first means for biasing said valve element upwardly relative to said valve guide,

a fluid reaction surface spaced downwardly yfrom said valve guide, said surface being movable relative to said valve guide, second means for biasing said reaction surface downwardly relative to said valve guide, and

frangible link means joining together said valve element and said lluid reaction surface, whereby upward flow of fluid tends to displace said valve element toward said valve seat and downward flow greater than a predetermined rate breaks said link causing said valve element and said surface to be movable independently.

2. Valve apparatus according to claim 1 wherein said first biasing means includes a coil spring between said valve element and said valve guide, and said second biasing means includes a coil spring between said reaction surface and said valve guide.

3. Valve apparatus according to claim 1 wherein said frangible link means includes a valve stern, said valve stem extending through said valve guide, and a breakable connection between said reaction surface and said valve stem.

4. Valve apparatus according to claim 1 wherein said reaction surface includes an orifice plate, and wall means surrounding the periphery of said orifice plate, said wall means and said valve seat means forming a continuous fluid passage through said body.

5. Valve apparatus according to claim 4 wherein said wall means is in the form of a tube, said frangible link means includes a valve stem, said valve stem extending through said valve guide, said tube being coaxial with said valve stem.

6. Valve apparatus according to claim 5 wherein said reaction surface includes a flexible washer overlying said orifice plate, said washer being on the upper side of said orifice plate, the peripheral edge of said washer being free to bend upwardly in response to fluid flow upwardly between said tube and said washer.

7. Valve apparatus according to claim 5 wherein said second biasing means includes a coil spring mounted coaxially on said valve stern, said spring imposing a biasing force on said orifice plate.

8. Valve apparatus according to claim 7 wherein said valve stem includes a sleeve and an extension arranged in telescoping relation, a rangible pin extending transversely through said sleeve and said extension, said orice plate being secured on said sleeve, whereby a downward force on said plate breaks said pin and displaces said sleeve downwardly relative to said extension.

9. Valve apparatus according t0 claim 8 including shoulder means on said extension limiting said downward displacement of said sleeve.

10. Valve apparatus according to claim 8 wherein said orifice plate is displaced out of said tube after said fran- 1 gible pin is broken.

References Cited UNITED STATES PATENTS Tilbury 166-224 X Baker 137-515 Pryor 137-68 X Brown 166-225 Baker 166-225 Baker et al. 166-225 Clark et al 166-225 X Lolacano 166-224 n CHARLES E. OCONNELL, Primary Examiner. a DAVID H. BROWN, Examiner.

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