Cementing Collar

Abstract

A cementing collar having a body and a valve sleeve therein which is releasably held closing cementing ports, a seat for receiving a plug to move the valve sleeve to cementing position, means for maintaining the valve sleeve in cementing position and means for releasing the maintaining means so that the valve sleeve is moved to a position closing the cementing ports.

Parent Case Text

This application is a continuation of application Ser. No. 715,874 filed Mar. 25, 1968 and now abandoned.

Description

BACKGROUND OF THE INVENTION

In the drilling of well bores it is often desired to cement the lower end of the well bore and also to cement the well bore at a position spaced above the lower end of the well bore. For this purpose, stage-cementing has been developed. Stage-cementing is performed by pumping cement into the pipe string which is placed at the bottom of the well bore, thereafter cementing ports in a cementing collar are opened by a plug which also shuts off the flow through the pipe string so that cement is pumped into the annulus and then a plug is used to close the pipe string and also to close the cementing ports to hold the cement in the annulus. Cementing collars used for stage-cementing have had two sleeves, both of which are initially shearpinned in an upper position closing the cementing ports through the collar. To open the cementing ports a plug is seated on the lower sleeve and the pressure in the pipe string develops sufficient force to shear the shearpins and to move the lower sleeve to the position uncovering the cementing ports. When cementing is completed, a second plug is seated on the upper sleeve and the pressure in the pipe string causes the pins to be sheared and the upper sleeve to be moved to close the cementing ports.

Difficulties have been encountered in stage-cementing with assuring that the cementing ports only open when desired and that the cementing ports close when the cementing is completed.

SUMMARY

The present invention relates to an improved cementing collar which is particularly adapted for use in stage-cementing of a well bore.

A object of the present invention is to provide an improved cementing collar which when moved to cementing position is positively stopped and held in such position.

Another object is to provide an improved cementing collar which may be positively closed and locked in closed position when cementing is completed.

A further object is to provide an improved cementing collar with a sleeve having a high-strength releasable stop to stop and hold the sleeve in cementing position wherein the stop may be released without having to exert excessive force.

Still another object is to provide an improved cementing collar in which the release mechanism allowing the collar to change from cementing position to closed position is not under stress during cementing.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages are hereinafter set forth and explained with reference to the description of the structure illustrated in the drawings wherein:

FIG. 1 is a longitudinal sectional view of the cementing collar of the present invention shown in its running-in position.

FIG. 2 is a similar sectional view showing the cementing collar in its cementing position.

FIG. 3 is another sectional view of the cementing collar showing the release of the retaining ring after cementing is completed.

FIG. 4 is another sectional view of the cementing collar showing it in closed position after completion of cementing.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The cementing collar illustrated in the drawings is adapted to be connected in a casing or pipe string to place cement in the annulus defined between the walls of a well bore and the exterior of the casing string at a location in the well bore above the lower end of the casing string. The cementing collar is run into the well bore on the casing string with its cementing ports closed and is actuated by a plug to open its cementing ports. When cementing of the annulus is completed, the cementing ports are closed by a second plug.

The running-in position of the cementing collar 10 is shown in FIG. 1. The tubular body 12 is threaded at its upper and lower ends for connection into a casing string and defines the cementing ports 14 providing communication between the interior and exterior of the body 12. The sleeve 16 is positioned within body 12 and as shown in FIG. 1, is releasably secured to body 12 to close off the ports 14. The means releasably securing sleeve 16 to body 12 is provided by the shearpins 18. Suitable sealing means is provided to seal between the exterior of sleeve 16 and the interior of body 12 both above and below the ports 14. The seals 20 and 22 positioned in the grooves 24 and 26 extending around the exterior of sleeve 16 illustrate such sealing means. In this position fluid flowing through the casing string flows freely through the collar 10.

In order for the cementing to proceed through the ports 14, the sleeve 16 is moved to a position at which the ports 28 defined in sleeve 16 are in registry with the ports 14 in the body 12. Also, a means should be provided to close the flow of fluids through the collar 10 at a point below the ports 28. The seat 30 defined in the lower end of sleeve 16 by the ring 32 is adapted to receive and seat the port-opening plug 34. With the plug 34 seated on seat 30, the pressure in the string above the plug 34 created by a surface pump provides sufficient force to shear the pins 18 between sleeve 16 and body 12, to move the sleeve downwardly and to close the flow through collar 10.

A means is provided to stop this downward movement of sleeve 16 at the position where the ports 28 are in registry with the ports 14 and such means retains the sleeve 16 in such position until cementing through the collar is completed. The snapring 36 provides such stop means and is positioned partially in the recess 38 which is defined around the upper exterior of sleeve 16. The interior of body 12 defines a shallow recess 40 to accommodate the portion of snapring 36 extending outwardly beyond the exterior of sleeve 16. The recess 40 extends downwardly and terminates in the upwardly facing shoulder 42 defined by the recess 44. The recess 44 is sufficiently deep to receive snapring 36. The engagement of the snapring 36 in recess 38 and against shoulder 42 positively stops the downward movement of sleeve 16 and retains sleeve 16 in its cementing position with ports 28 in registry with ports 14. Snapring 36 is preferred to have sufficient strength in shear to retain sleeve 16 in cementing position even though the pressure above the plug 34 reaches the rupture pressure of the casing string. This strength of snapring 36 is easily accomplished because of the large area (the circumference around sleeve 16, times the height of snapring 36) which is in shear. Snapring 36 is biased inwardly so that it remains in engagement within recess 38 until positively moved therefrom as hereinafter described. Snapring 36 or any other stop-and-retaining means such as a plurality of arcuate segments positioned in recess 38 should be biased inwardly and have sufficient strength to stop and retain sleeve 16 in cementing position.

Guiding means is provided by the coaction of pins 46 secured in body 12 extending into longitudinal grooves 48 on the exterior of sleeve 16 to prevent rotation of sleeve 16 within body 12. Such guiding means assures that the ports 14 and 28 are aligned when sleeve 16 is in its intermediate or cementing position. Also sealing means is provided between sleeve 16 and body 12 above and below the cementing ports to prevent the accumulation of cement therebetween. Seal 20 in groove 24 and seal 50 in groove 52 defined around the exterior of sleeve 16 above ports 28 provide such sealing.

Upon completion of the cementing through collar 10, the sleeve 16 is moved downwardly within body 12 so that the ports 28 do not register with the ports 14. To move sleeve 16 downwardly, a means is provided for releasing the holding means. Such release means is adapted to receive the port closing plug 54 and to be responsive to the force exerted by the plug 54 which force is caused by the pressure of fluid pumped into the string above the plug. The cam ring 56 functions as such release means. Cam ring 56 is releasably secured within the upper end of sleeve 16 by shearpins 18 and defines the seat 58 for receiving the plug 54. The cam ring 56 defines the cam surface 60 on its exterior below shearpins 18. The cam surface 60 tapers downwardly and inwardly and terminates in the shoulder 62. When properly assembled with sleeve 16, the pins 64 which extend radially through sleeve 16 are engaged between snapring 36 at their outer end and the cam surface 60 at their inner end and also abut the shoulder 62. A sufficient number of the pins 64 should be used so that as cam ring 56 moves downwardly and the cam surface 64 forces the pins 64 outwardly, the snapring 36 is uniformly forced into the recess 44 as shown in FIG. 3. With snapring in this position, sleeve 16 is free to move downward and the force of plug 54 is exerted by engagement of the downward facing shoulder 66 on the exterior of cam ring 56 with the upward facing shoulder 68 on the interior of sleeve 16 to move sleeve to the position closing the cementing ports as shown in FIG. 4.

The pins 70 positioned in sleeve 16 project into slots 72 defined on the lower exterior of cam ring 56 guide the downward movement of cam ring 56 within sleeve 16 and provide a stop for the movement of cam ring 56. Seals 74 and 76 are positioned in the grooves 78 and 80 extending around the exterior of sleeve 16 and are adapted to seal against the interior of body 12 above and below ports 14.

In the closing of the cementing ports, there is no relative movement between the plugs 54 and 34 after the sleeve 16 has started its downward movement. The relative movement of plug 54 toward plug 34 in cam ring 56 is accomplished while the ports 14 and 28 are still open. Some prior cementing collars required a relative movement between the plugs to complete the closing. Since the cement is noncompressible, the closing movement in these prior devices may not be completed to a sealed position and cement from the annulus may leak back into the collar. This problem is avoided with the cementing collar of the present invention since none of its movements are against a trapped volume of cement.

When the sleeve 16 has moved to its closed position, the recess 82 defined in the exterior of sleeve 16 is positioned opposite the recess 44. Snapring 36, which is biased inwardly, moves into engagement with recess 82. Because recess 82 is relatively shallow, snapring 36 remains partially within recess 44 when it moves into recess 82. Snapring 36 thus provides a means-locking sleeve 16 in its closed position to assure that the cement in the annulus does not flow back into the cementing collar.

From the foregoing, it can be seen that the cementing collar of the present invention is positively moved to open position, is held in open position until cementing is completed and is then positively moved to closed position. The means holding the cementing collar in cementing position may be constructed to withstand pressures greater than the rupture pressure of the string in which the collar is connected. Further, this retaining means is simply and easily released from its holding position responsive to pressure when cementing is completed without subjecting the string to excessively high pressures. The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

Claims

What is claimed is:

1. A cementing collar comprising: an elongated tubular body having a central bore extending therethrough and means for connecting said body to a well pipe string and with at least one transversely extending port communicating between the exterior and interior of said tubular body; an elongated tubular sleeve axially received within said bore of said tubular body having a central bore extending therethrough and with at least one transversely extending orifice communicating between the exterior and interior of said sleeve; first frangible securing means for releasably securing said sleeve in an upper position, said upper position registering as solid peripheral portion of said sleeve adjacent said port; first releasing means received within said body for releasing said first securing means such that said sleeve takes an intermediate position, said intermediate position registering said orifice adjacent said port and opening said port into communication with the interior of said sleeve; second securing means which are cooperable with a portion of said first securing means to releasably secure said sleeve in said intermediate position; second releasing means received within said body for releasing said second securing means and said portion of said first securing means such that said sleeve takes a lower position, said lower position registering a solid peripheral portion of said sleeve adjacent said port; and third securing means for releasably securing said sleeve in said third position.

2. A cementing collar as specified in claim 1 wherein when said sleeve is in said upper and lower positions said port is sealed from communication with the interior of said sleeve and the interior of said tubular body and when said sleeve is in said intermediate position said port is sealed from communication with the interior of said tubular body only.

3. A cementing collar as specified in claim 1 wherein said sleeve defines an inner upwardly facing seat within the lower end thereof and said first releasing means includes a plug member sealingly seatable on said seat.

4. A cementing collar as specified in claim 1 wherein said second releasing means includes: a tubular cam member axially received within the upper end of said bore of said sleeve and having a central bore extending therethrough and an inner upwardly facing seat within the upper end thereof; and a plug member sealingly seatable on said seat.

5. A cementing collar as specified in claim 4 wherein said first securing means releasably secures said cam member to said body and said sleeve and said portion of said first securing means releasably secures said cam member to said sleeve only.

6. A cementing collar as specified in claim 5 wherein said second securing means additionally includes: a first peripheral recess around the exterior of said sleeve; a second peripheral recess around the interior of said body and defining a shoulder at the lower end thereof; and a radially inwardly biased radially movable retaining ring positioned in said first recess and adapted to simultaneously engage said shoulder and at least a portion of said first recess to secure said sleeve in the intermediate position thereof.

7. A cementing device as specified in claim 5 wherein said first securing means includes a plurality of shearpins each of which are received within respective ones of aligned bores which extend laterally through said body, said sleeve and said cam member.

8. A cementing device as specified in claim 1 additionally including guiding means to assure said port registers into communication with the interior of said sleeve when said sleeve is in the intermediate position thereof.

9. A cementing collar as specified in claim 6 wherein said second releasing means additionally includes a plurality of pins being slidably received within respective bores extending radially through said sleeves, and said pins adapted to coacting with an outer peripheral cam surface of said cam member to engage said retaining ring and move said retaining ring and move said retaining ring radially outward out of engagement with said portion of said first recess.

10. A cementing collar as specified in claim 6 wherein said third securing means includes: a third peripheral recess around the exterior of said sleeve being spaced axially upwardly from said first peripheral recess, said retaining ring adapted to simultaneously engage said shoulder and at least a portion of said third recess to secure said sleeve in the lower position thereof.