Cementing Tool

Abstract

A cementing tool for providing multiple stage cementing of an oil well has an outer case, a closing sleeve located concentrically therein, upper and lower adapters, a releasing sleeve, an opening sleeve, and a sleeve retainer located within the closing sleeve.

Description

BACKGROUND OF THE INVENTION

In preparing oil well bore holes for oil and/or gas production a most important step involves the process of cementing.

Basically, oil well cementing is a process of mixing a cement-water slurry and pumping it down through steel casing to critical points located in the annulus around the casing, in the open hole below, or in fractured formations.

Cementing a well protects possible productive zones behind the casing against salt water flow and protects the casing against corrosion from subsurface mineral waters and electrolysis from outside.

Cementing eliminates the danger of fresh drinking water and recreational water supply strata from being contaminated by oil or salt water flow through the bore hole from formations containing those substances. It further prevents oil well blowouts and fires caused by high pressure gas zones behind the casing and prevents collapse of the casing from high external pressures which can build up underground.

A cementing operation for protection against the above described downhole conditions is called primary cementing. Secondary cementing includes the cementing processes used on a well during its productive life, such as remedial cementing and repairs to existing cemented areas. The present invention is generally useful in primary cementing.

In the early days of oil field production, when wells were all relatively shallow, cementing was accomplished by flowing the cement slurry down the casing and back up the outside of the casing in the annulus between the casing and the bore hole wall.

As wells were drilled deeper and deeper to locate petroleum products, it became difficult to successfully cement the entire well from the bottom of the casing and multiple stage cementing was developed to allow the annulus to be cemented in separate stages, beginning at the bottom of the well and working up.

This process is achieved by placing cementing tools, which are primarily valved ports, in the casing or between joints of casing at one or more locations in the bore hole, flowing through the bottom of the casing, up the annulus to the lowest cementing tool in the well, closing off the bottom, opening the cementing tool, and then flowing through the cementing tool up the annulus to the next upper stage and repeating this process until all stages are completed.

Cementing tools used for multi-stage cementing usually have two sleeves, both of which are usually shear-pinned initially in an upper position, closing the cementing ports in the tool. To open the cementing ports a plug is flowed down the casing and seated on the lower sleeve. The fluid pressure is then increased in the casing until sufficient force is developed on the plug and sleeve to shear the shear pins and move the lower sleeve to the position uncovering the cementing ports. Cement is then flowed down the casing and out the open ports into the annulus. When the predetermined desired amount of cement has been flowed into the annulus, another plug is placed in the casing behind the cement and flowed down the casing to seat on the upper sleeve. The pressure is increased on the second plug until the shear pins holding it are severed and the upper sleeve is moved down to close the cementing ports.

The difficulty arises when the second plug is flowed in to close the ports and as the ports begin to close a hydraulic lock occurs between the two plugs due to the incompressibility of the cement slurry trapped between them and the second sleeve does not travel the sufficient distance to close and seal off the ports. Thereafter when pressure in the casing is relieved, the upper sleeve may float back open and allow the cement to reverse flow from the annulus back into the casing.

Another difficulty inherent in the prior art devices is that the lower sleeve or the upper sleeve or both may become actuated prematurely causing a misrun and necessitating a large amount of time and expense to correct.

The present invention overcomes these difficulties by providing a cementing tool with positive opening and closing action, with a locking device to prevent premature opening, locking means to prevent opening after the cementing has been completed, and means to prevent a hydraulic lock between the opening and closing plugs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of the cementing tool of this invention.

FIG. 2 is an isometric view of the closing sleeve of the cementing tool of FIG. 1.

FIGS. 3 through 6 are schematic diagrams showing the method of operation of this tool.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the cementing tool 1 has a tubular outer case 2 to which is attached upper adapter 3 and lower adapter 4. These can be connected together by any conventional means such as welding at 5 and 6 as well as threaded connections at 7 and 8. Upper adapter 3 and lower adapter 4 may be threaded at their extreme ends or otherwise arranged to fit between standard sections of casing or other pipe or can be adapted to be welded in place in the casing where the casing must be cut and the cementing tool inserted therein.

Outer case 2 is a cylindrical tubular housing having an inner diameter larger than the inner diameter of the casing or pipe string in which it is inserted. It is made of a tough durable material such as steel or stainless steel. Passing through the wall of case 2 are two or more ports 9. Passing circumferentially around the inner surface of case 2 and intersecting ports 9 is inner annular recess 10.

Outer case 2 also contains inner annular recess 11 having sloping walls 12 and 13. Also located in the case 2 is sloping wall 14 which, in conjunction with wall 12, forms inner annular shoulder 15.

Located near the bottom of outer case 2 is a third inner annular recess 16 having a perpendicular face 17 and a sloping wall 18.

Closing sleeve 20 is a tubular cylindrical sleeve located concentrically within case 2 and having an outer diameter slightly less than that of case 2 so that the sleeve 20 can slide within case 2 without needing undue force to overcome friction between the walls. Sleeve 20 has an inner diameter substantially equal to that of the casing or pipe string in which the cementing tool is located, and is also made of a tough durable material such as steel or stainless steel.

Closing sleeve 20 has two or more ports 19 passing therethrough preferably aligned with ports 9 of case 2. Sleeve 20 also has at its upper end, a collet ring 21 formed by outer annular ridge 22 formed on sleeve 20 and inner annular recess 23 cut in it. Collect ring 21 is comprised of collet fingers 24 (FIG. 2) formed in the upper end of sleeve 20 by equispaced machined grooves 25 cut into sleeve 20 extending through annular ridge 22 and recess 23.

One or more annular recesses 26 located circumferentially about the exterior of sleeve 20, above and below ports 19, retain elastomeric seal means 27, 27a and 27b which provide a fluidic seal between sleeve 20 and case 2, above and below ports 9 and 19.

Sleeve 20 also has an external circumferential grooved channel not shown passing around the sleeve and intersecting ports 19. This channel and recess 10 in case 2 provide fluid communication between ports 9 and 19 should sleeve 20 become rotated within case 2 during the cementing operation.

Channel 29 in sleeve 20 contains expanding lock rings 30 which are compressed into channel 29. When channel 29 moves adjacent to recess 16 in case 2 the lock rings 30 expand into recess 16, and partially out of channel 29 and because of abutment with face 17 and channel 29, sleeve 20 cannot move back upward within case 2. This provides the locked closed feature of the tool which occurs after cementing has been completed. The collet fingers 21 have ridge 22 abutted against face 14 of case 2 to prevent premature movement of sleeve 2 before cementing is completed through the tool.

Sleeve 20 also has an inner annular recess 31 located below ports 19 and having perpendicular faces 32 and 33.

Located concentrically within closing sleeve 20 are releasing sleeve 34, opening sleeve 35 and sleeve retainer 36. Opening sleeve 35 is a cylindrical collar snugly fitting within closing sleeve 20, and having a beveled plug seat 37, and is initially placed to cover ports 19 and 9. Opening sleeve 35 is held in closed position over ports 9 and 19 by shear pins 38 threadedly engaged in closing sleeve 20 and opening sleeve 35 in the same plane as ports 19 and 9. The shear pins have been rotated in FIG. 1 for purposes of illustration only.

Opening sleeve 35 also has annular recesses 40 located above and below shear pins 38 for receiving circular seals 41 which provide fluid sealing between opening sleeve 35 and closing sleeve 20. Opening sleeve 35 also has recess 42 passing circumferentially around it to receive expanding lock ring 43 which is compressed into recess 42 and which ring is capable of expanding partially into recess 31 of sleeve 20 when recess 42 is aligned with recess 31. This provides a locking arrangement between sleeve 35 and sleeve 20 when sleeve 35 has been moved into the open-port cementing position.

Located directly above opening sleeve 35 and abutting the upper face 44 of sleeve 35 is releasing sleeve 34 which is a cylindrical tubular sleeve having a narrowed skirt 45 at its lower end and raised shoulder 46 at its upper end. Narrowed skirt 45 in conjunction with closing sleeve 20 forms annular area 47 communicating from the lower end 48 of skirt 45 to sloping face 49 of the releasing sleeve.

Raised shoulder 46 is an annular shoulder contacting collet fingers 24 maintaining them in their outward position in abutment with case 2 at shoulder 14 which prevents closing sleeve 20 from moving downward and closing off ports 9. Releasing sleeve 34 is attached initially to closing sleeve 20 by shear pins 50, passing through sleeve 20 and sleeve 34. Circular seals 51 in annular recesses in releasing sleeve 34 provide a fluidic seal between the upper part of sleeve 34 and the closing sleeve 20. Plug seat 52 is formed on the upper inner edge of sleeve 34 by beveling the inner edge of the sleeve end.

Sleeve retainer 36 is a circular ring fixedly attached to the lower interior end of closing sleeve 20. As shown, it is attached by a snugly matching threaded connection 53. Retainer 36 is adapted and located essentially to abut opening sleeve 35 in its lowermost position and further aid lock ring 43 in preventing extreme downward movement of opening sleeve 35 in closing sleeve 20. Sleeve retainer 36 also provides an additional force transmitting means from opening sleeve 35 to closing sleeve 20.

It is desirable to make releasing sleeve 34, opening sleeve 35, and sleeve retainer 36 of some easily drilled material such as aluminum, aluminum alloy, brass, bronze, or cast iron, so that these parts may be easily drilled out of the tool after cementing is completed, thereby providing a fully opened passage through the cementing tool.

In typical operation, referring now to FIGS. 3 through 6, the cementing tool 1 is placed in the casing or pipe string 55 before it is run in the hole. It may be inserted between standard threaded sections of the pipe at the desired locations of cementing stages to be performed. A number of cementing stages are possible with this tool as long as each cementing tool in the pipe string has a smaller inner diameter than the cementing tool immediately above it.

After the pipe string or casing is in place in the hole, the first or lowermost stage of cementing may be accomplished through the bottom of the pipe string 56 and up the annulus 57. A wiper plug 58 is inserted behind the first stage of cement slurry, and displacing fluid of approximately the same specific gravity as the cement slurry is pumped behind the wiper plug to displace the cement from the pipe string.

After a precalculated amount of displacing fluid, sufficient to fill the pipe string from the bottom 56 to the next upper cementing tool, has been pumped into the pipe string, an opening plug 54 is inserted in the pipe and flowed down to seat on plug seat 37 of opening sleeve 35, fluidically sealing off the opening through the cementing tool. Alternatively, a bomb or ball can be dropped through the fluid in the pipe to seal it off. A precalculated amount of cement slurry sufficient to complete cementing of the second stage, is flowed behind opening plug 54.

Pressure sufficient to shear the shear pins 38 is then applied to the cement slurry and fluid in the pipeline, which pressure, acting through plug 54, shears pins 38 and forces opening sleeve 35 downward, exposing ports 19 and 9. Cement then flows through the ports and up the annulus 59. The tool is then in the position shown in FIG. 4. Lock ring 42 has engaged in recess 31 thereby preventing any upward shifting of the opening sleeve in the closing sleeve.

When a precalculated amount of cement sufficient to complete the second stage has been pumped into the pipe, a closing plug 59 is pumped behind the cement followed by displacing fluid. Closing plug 59 seats in plug seat 52 closing off the passage therethrough and, when fluidic pressure reaches a predetermined sufficient level on plug 59, the shear pins 50 are sheared allowing sleeve 34 to move downward out of abutting contact with collet ring 21. Recess 47 allows cement trapped between plugs 54 and 59 to continue to exit through ports 19 and 9, thereby preventing a hydraulic lock therebetween. Continued pressure on plug 59 forces sleeve 34 to its lowermost position with shoulder 60 abutting face 61 of sleeve 20.

A sufficient predetermined pressure force transmitted through plug 59 then acts downward on sleeve 34, through shoulder 46, abutting face 60 of sleeve 34 with face 61 of sleeve 20 thereby transmitting force to sleeve 20, overcoming the spring force in collet fingers 24, and allowing collet ring 21 to be compressed inward, moving past shoulder 14 and downward therefrom. This in turn moves ports 19 downward and out of alignment with ports 9 and passes seals 27b below ports 9 thereby fluidically sealing ports 9 from the interior bore of the cementing tool 1. At this point lock rings 30 in recess 29 have come adjacent to recess 16 and expanded part of the way thereinto thereby preventing any movement of sleeve 20 back upwards. Downward travel of sleeve 20 in housing 2 is limited by lower end 62 of sleeve 20 abutting upper end 63 of lower adapter 4. It should be noted that before closing sleeve 20 is moved downward, plugs 54 and 59 have become stationary with respect to each other and there is no more possibility of a hydraulic lock between them.

Closing ports 9 completes this cementing stage and the next cementing stage can begin. After the final stage is completed the bore passage obstructions consisting of sleeves 34, 35, and 36, plugs 54 and 59, and the cement between plugs 54 and 59, can be easily drilled out leaving the bore passage completely open and unobstructed for subsequent operations therethrough.

Although a specific preferred embodiment of the present invention has been described in the detailed description above, the description is not intended to limit the invention to the particular forms or embodiments disclosed herein, since they are to be recognized as illustrative rather than restrictive and it will be obvious to those skilled in the art that the invention is not so limited. For example the collet ring locking device of this invention could be replaced with a snap ring type locking device. Also, where seals having polygonal cross sections are revealed, it would be obvious to substitute O-ring seals or other type seal means therefor. Likewise, other shear means than shear pins could be used advantageously. The invention is declared to cover all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration, which do not constitute departures from the spirit and scope of the invention.

Claims

What is claimed is:

1. A cementing tool for cementing through a pipe string or casing comprising:

a. a tubular housing containing one or more outer cementing ports through the wall;

b. means for interposing said tubular housing between pipe sections in a string of pipe and attaching said housing to the pipe;

c. a closing sleeve slidably located within said tubular housing and containing one or more inner cementing ports through the wall; said closing sleeve in one position allowing said outer ports and said inner ports to communicate therethrough and in a second position isolating said inner ports from said outer ports; said closing sleeve having a large unrestricted bore therethrough with a relatively constant inner diameter substantially equivalent to the inner diameter of the pipe string or casing;

d. an opening sleeve slidably located within said closing sleeve and covering said inner ports in a first position and uncovering said ports in a second position; said opening sleeve having a large unrestricted bore therethrough of substantially constant diameter and only slightly smaller in diameter than said closing sleeve;

e. spring means on said closing sleeve engaging said housing, said spring means adapted to retain said closing sleeve in an open-port position until sufficient force is applied downward on said sleeve to overcome said spring means;

f. a releasing sleeve slidably located within said closing sleeve and arranged in a first upper position to maintain said spring means engaged in said housing and in a second position to release said spring means and engage said closing sleeve to move it downward; said releasing sleeve having a large unrestricted bore therethrough with a substantially constant inner diameter which is only slightly smaller than the diameter of the pipestring or casing;

g. a sleeve retainer fixedly located within said closing sleeve and adapted to limit downward movement of said opening sleeve; said retainer having an open unrestricted bore therethrough substantially equal to that of said opening sleeve;

h. first shear means contained in said closing sleeve and said opening sleeve, attaching said opening sleeve to said closing sleeve and arranged to maintain said opening sleeve covering said inner ports;

i. second shear means contained in said releasing sleeve and said closing sleeve and attaching said releasing sleeve to said closing sleeve;

j. means for selectively shearing said first and second shear means further comprising first activating means and second activating means, said first activating means further adapted to fluidically seal the bore of said opening sleeve and said second activating means adapted to fluidically seal the bore of said releasing means, said first activating means arranged to shear said first shear means and said second activating means arranged to shear said second shear means; and

k. and recess means in the exterior surface of the lower end of said releasing sleeve, said recess means arranged to prevent fluid lock between said first activating means and said second activating means by fluidically communicating between said outer and inner cementing ports and the area trapped between said first and second activating means.

2. The cementing tool of claim 1 further comprising first spring locking means between said closing sleeve and said housing for preventing upward movement of said closing sleeve in said housing after said closing sleeve has been moved into closed-port position, and second spring locking means between said opening sleeve and said closing sleeve for preventing upward movement of said opening sleeve in said closing sleeve after said opening sleeve has moved downward into open-port relationship in said closing sleeve.

3. The apparatus of claim 2 further comprising seal means between said closing sleeve and said housing, seal means between said releasing sleeve and said closing sleeve, and seal means between said opening sleeve and said closing sleeve, said seal means between said closing sleeve and said housing comprising relatively elongated cylindrical circular seal means of elastomeric material.

4. The apparatus of claim 1 wherein said first activating means comprises a plug member adapted to be flowed into the pipe string through said releasing sleeve, and seated on said opening sleeve, said opening sleeve having a beveled inwardly and upwardly facing plug seat arranged to receive said plug member in fluidically sealing arrangement; said plug member having a plurality of resilient wiper elements thereon capable of engaging the casing wall and further having a beveled sealing surface located thereon to sealingly engage said opening sleeve plug seat; and said second activating means comprises a second plug member adapted to be flowed into the pipe string to seat on said releasing sleeve, with said releasing sleeve having a beveled inwardly and upwardly facing plug seat arranged to receive said plug member in fluidically sealing arrangement; said second plug member having a plurality of resilient wiper elements thereon capable of engaging the casing wall and further having a beveled sealing surface located thereon to sealingly engage said releasing sleeve plug seat; and said plug seat in said opening sleeve having smaller diameter than said plug seat in said releasing sleeve.

5. The apparatus of claim 4 wherein said housing further comprises an inner annular recess intersecting and providing fluid communication between said outer ports, and said closing sleeve further comprises an outer circumferential channel intersecting and providing fluid communication between said inner ports, said inner annular recess and said outer circumferential channel arranged to conjoin and provide fluid communication between said inner ports and said outer ports should they become radially misaligned when said closing sleeve is in the uppermost, open-port position and said opening sleeve is in its lowermost, open-port position.

6. A cementing tool adapted to be interposed between adjoining sections of pipe and having an inner bore portion, comprising:

a. a cylindrical hollow outer casing having a bore portion passing longitudinally therethrough and one or more outer cementing ports passing through the wall thereof;

b. first sleeve means mounted within said outer casing and having one or more inner cementing ports arranged to communicate with said outer ports in a first position of said first sleeve means and said first sleeve means adapted to be movable to a second position wherein said outer ports are fluidically sealed from the bore portion of said cementing tool;

c. second sleeve means located within said first sleeve means, attached to said first sleeve means by first shear means, and arranged to cover said inner and outer ports in a first, closed position and arranged to uncover said ports in a second open position;

d. third sleeve means also located within said first sleeve means and attached to said first sleeve means by second shear means;

e. spring means located on said first sleeve means between said third sleeve means and said casing for maintaining said first sleeve means in said first position of said first sleeve means, said spring means adapted to be released by said third sleeve means when said third sleeve means moves to a lower position within said first sleeve means;

f. means for engaging said second sleeve means and for shearing said first shear means;

g. means for engaging said third sleeve means, moving said third sleeve means downward, shearing said second shear means, and releasing said spring means;

h. locking spring means between said first sleeve means and said casing and arranged to mechanically lock said first sleeve means in its lowermost position within said casing;

i. locking means between said second sleeve means and said first sleeve means and adapted to lock said second sleeve means in its lowermost position in said first sleeve means;

j. seal means located between said casing, said first sleeve means, said second sleeve means, and said third sleeve means, and arranged to fluidically seal between the walls thereof;

k. retaining means located within said first sleeve means and adapted to further limit downward travel of said second sleeve means in said first sleeve means; and

l. fluidic lock prevention means between said first sleeve means and said third sleeve means for preventing the trapping of hydraulic pressure between said means for engaging said second sleeve means and said means for engaging said third sleeve means.

7. The cementing tool of claim 6 wherein said spring means comprises a collet ring formed of collet fingers extending upwardly from said first sleeve means, said collet fingers each having an inner and outer projected shoulder, which said shoulders on said fingers act in conjunction to form a collet ring in abutment with said casing and said third sleeve means, and adapted to remain locked in abutment with said casing until said third sleeve means is moved downward, out of abutment with said collet ring.

8. The cementing tool of claim 7 wherein said means for engaging said second sleeve means and for shearing said first shear means comprises a first plug member adapted to be pumped into the pipeline under pressure, said second sleeve means having a beveled upper inner edge forming a plug member seat wherein said first plug member seats and fluidically seals off said second sleeve means.

9. The cementing tool of claim 8 wherein said means for engaging said third sleeve means and for shearing said second shear means comprises a second plug member having a larger diameter than said first plug member and also adapted for being pumped into a pipeline under pressure, said third sleeve means having a beveled upper inner edge forming a plug member seat wherein said second plug member seats and fluidically seals off said second sleeve means, said plug member seat in said third sleeve means having a larger inner diameter than said seat in said second sleeve means, sufficient to allow said first plug member to pass through said third sleeve means relatively unhindered.