GB2041045A - Inflatable Packer Assembly with Control Valve - Google Patents

Abstract

An inflatable packer assembly for a well includes a cylindrical mandrel 18 with a cylindrical valve body 24 concentrically disposed about the mandrel, and arranged for directing fluid under pressure to an inflatable packer element 20 also disposed about the mandrel. A cylindrical outer surface of the mandrel is closely received within a cylindrical inner surface of the valve body with said surface of the mandrel projecting beyond the opposite ends of the valve body. <IMAGE>

Description

SPECIFICATION Inflatable Packer Assembly with Control Valve This invention relates to an inflatable packer assembly for use with a casing or other tubular member of a well.

An inflatable packer is a downhole tool which can be inflated with well fluid to seal off the annular space between, for example, the casing and the wellbore. It may also be used inside a casing.

Inflatable packers may be used in a well for a variety of reasons. They can be used to support a column of cement above a lost circulation zone.

They. can be used to isolate producing zones from cementing operations. Also, they may be used to isolate production and lost circulation zones for gravel pack operations.

Typical prior art control valves for inflatable packers have included both spring loaded check valves, and various forms of sliding sleeve valves, for controlling the flow of well fluid to the inflatable element to inflate the same.

Examples of spring loaded check valves are disclosed in U.S. Patents Nos. 3,437,142 to Conover, No. 3,085,628 to Malone, and No.

2,177,601 to Smith. Examples of sliding sleeve valves are disclosed in U.S. Patent No. 3,524,503 to Baker and No. 3,053,322 to Kiln.

In accordance with the present invention there is provided an inflatable packer assembly, comprising a cylindrical mandrel, a packer disposed about an outer cylindrical surface of said mandrel, said packer including an inflatable element, and valve means, connected to said packer, for directing fluid under pressure to said packer to inflate said element, said valve means including a cylindrical valve body having first and second ends with a cylindrical inner surface connecting said first and second ends, said cylindrical outer surface of said mandrel being closely received within said cylindrical inner surface of said valve means and said cylindrical outer surface of said mandrel extending past each of said first and second ends of said valve means.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic partly sectional elevation illustration of the inflatable packer assembly with control valve, in accordance with the present invention, in place within an oil well borehole; Figures 2A-2C comprise an enlarged sectional elevation view of the inflatable packer assembly with control valve of Figure 1; Figure 3 is an isometric view of the control valve with a portion of the wall thereof removed to show the piston bores and interconnecting ports; Figure 4 is a schematic representation of the piston bores and ports of the valve of Figure 3; and Figure 5 is an enlarged view of the counterbore 96 of second bore 56 of the valve of Figure 3.

Referring now to the drawings, and particularly to Figure 1, the inflatable packer assembly of the present invention is shown and generally designated by the numeral 1 0. The inflatable packer assembly 10, which may more generally be referred to as a downhole tool, is generally connected as an integral part of a casing string 12, which may generally be referred to as a tubular member. The casing string 12 is disposed in a borehole or well hole 14 of an oil well so that there is an annular cavity or space 16 between casing string 12 and well hole 14. It will be understood by those skilled in the art, that the present invention could be equally well applied to a downhole tool connected to a drill string located within a well hole defined by an inner surface of a well casing.

The inflatable packer assembly 10 includes a cylindrical mandrel 18 having an inflatable element which may be referred to as a bladder means or packer 20 connected to the mandrel 1 8 for sealing said annular cavity 1 6. The bladder means 20 and the mandrel 18 define an annular fluid-filled space 22 therebetween when said bladder means 20 is inflated to seal said cavity 16.

A valve means generally designated by the numeral 24 includes an inlet 26 communicating with an interior of tubular member 12 through an interior 28 of said mandrel 18, and an outlet 30 communicating said annular space 22. The valve means 24 communicates said interior 28 of said mandrel 18 with said annular space 22 when a fluid pressure differential between said interior 28 of said mandrel 18 and said cavity 1 6 adjacent a lower end 54 of said valve means 24 reaches a first predetermined level, so that fluid from said interior 28'flows into said annular space 22 to inflate said bladder means 20 as illustrated in Fig.

1.

The valve means 24 also includes a means for isolating said interior 28 from said annular space 22 when said pressure differential reaches a second level higher than said first level, while preventing any loss of fluid from said annular space 22 as said interior 28 is being isolated therefrom.

Referring now to Figs. 2A-2C, the inflatable packer assembly 10 includes an upper body 32 threadedly connected to an upper end 34 of mandrel 18 for connecting mandrel 18 to the casing string 12.

The bladder means 20 is connected at its upper and lower ends to upper and lower packer shoes 36 and 38, respectively.

Upper packer shoe 36 sealingly engages an outer cylindrical surface 40 of mandrel 1 8 with a plurality of O-rings 42. When bladder means 20 is in the uninflated position shown in Fig. 2 the upper packer shoe 36 abuts an upper backup ring 44. Upper backup ring 44 is welded to outer cylindrical surface 40 of mandrel 18 as indicated at 46.

Valve means 24 includes a cylindrical valve body 48 concentrically disposed about outer surface 40 of mandrel 1 8. The cylindrical valve body 48 includes the inlet 26 which is permanently aligned with a hole 50 disposed through a wall of said mandrel 18 and communicating with said interior 28 of mandrel 18.

Valve body 24 also includes the output 30 for directing fluid from the interior 28 to the annular fluid-filled space 22 of bladder means 20. Biadder means 20 may also be referred to as a component of the downhole tool which is to be actuated by said fluid from the interior of mandrel 1 8.

As is best seen in Figs. 3 and 4, the valve body 48 further includes a first axial bore 52 connecting said inlet 26 with an end surface 54 of said cylindrical valve body 48. Valve body 48 also includes a second axial bore 56 communicating with said end 54 of valve body 48. End surface 54 communicates with the annular space 1 6 about outer cylindrical surface 40 of mandrel 1 8.

A first port means, generally designated by the numeral 58, interconnects said first and second bores 52 and 56. First port means 58 comprises a third axial bore 60 which s intersected by first and second crossbores 62 and 64. Crossbores 62 and 64 also intersect first and second axial bores 52 and 56.

A second port means, generally indicated by the numeral 66 interconnects second bore 56 with outlet 30. Second port means 66 comprises a fourth axial bore 68 connecting first end 54 of valve body 24 with outlet 30. Second port means 66 further comprises a third crossbore 70 intersecting second and fourth axial bores 56 and 68.

Those ends of third and fourth axial bores 60 and 68, and of first, second and third crossbores 62, 64 and 70, which communicate with first end 54 of valve body 48 or with radially outer surface 72 of valve body 48 are sealed after being drilled, with pipe plugs 74 as shown in Fig. 4.

A first or primary piston 76 is slidably disposed in first bore 52. First piston 76 has first and second ends 78 and 80, respectively, which are in fluid communication with said inlet 26 and said first end 54 of valve body 48, respectively.

First piston 76 is movable between a first position, illustrated in Fig. 4, blocking said first port means 58 and a second position (displaced to the right from the position shown in Fig. 4 so as to abut lower backup ring 134) allowing fluid communication between said inlet 26 and said first port means 58. When first piston 76 is in said second position, the first end 78 is displaced to the right past first crossbore 62, so that inlet 26 is communicated with first crossbore 62.

Referring to Fig. 20 the first piston 76 is there shown in its first position. First piston or primary piston 76 is connected to valve body 48 by a first shear pin 82. Shear pin 82 may be referred to as a means for holding first piston 76 in said first position until a fluid pressure differential between interior 28 of mandrel 1 8 and said first end 54 of valve body 48, i.e. annular space 16, reaches a first level, and for releasing first piston 76 so that it may be moved to said second position by said pressure differential when said differential reaches said first level.

First piston 76 includes a reduced diameter portion 83, between first and second ends 78 and 80 thereof. It is very difficult to manufacture a long bore of relatively small diameter, such as first bore 52, which is absolutely straight. The bore 52 generally will have some very slight curve or other irregularity from the desired straight line of bore.

The reduced diameter portion 83 of first piston 76 gives piston 76 sufficient flexibility so that it may bend slightly to accommodate such irregularities in bore 52 when piston 76 is moving between its said first and second positions within bore 52.

This provides an advantage over a constant diameter piston which would have more of a tendencytotecorne stuck within an irregular bore.

A second piston 84 is slidably disposed in second bore 56. Second piston 84 includes first and second ends 86 and 88, respectively. The first end 86 is in fluid communication with first port means 58 and second end 88 is in fluid communication with said first end 54 of valve body 48 which communicates with annular space 16.

Second piston 84 is movable between a first position, illustrated in Fig. 4, allowing fluid communication between said first and second port means 58 and 66, respectively, and a second position (displaced to the right from that shown in Fig. 4 so as to block third crossbore 70) blocking said second port means 66.

Second piston 84 includes a middle portion 90 of reduced diameter, so that when second piston 84 is in said first position said first and second port means 58 and 66 are communicated through said second bore 56 around said reduced diameter middle portion 90 of second piston 84.

Second piston 84 is connected to valve body 48, when in the first position illustrated in Fig. 4, by a shear pin (not shown) similar to shear pin 82.

The shear pin connecting second piston 84 to valve body 48 may also be referred to as a means for holding said second piston 84 in said first position until said fluid pressure differential between said interior 28 and said first end 54 of valve body 48 reaches a second level, said second level being higher than said first level, and for releasing said second piston 84 so that it may be moved to its said second position by said pressure differential when said pressure differential reaches said second level.

First and second pistons 76 and 84 each include a plurality of O-rings 92 for sealing against their respective bores 52 and 56.

Second piston 84 includes an outer annular groove containing an expandable metal retaining ring 94. When second piston 84 is displaced to the right from the position shown in Fig. 4 to its second position, retaining ring 94 expands and engages a counterbore 96 which is concentric with second bore 56 and communicates with first end 54 of valve body 24. This locks second piston 84 into said second position, and permanently and automatically isolates interior 28 from the annular space 22 when the pressure differential reaches said second level.

Referring to Fig. 5 the details of construction of counterbore 96 are illustrated. A shoulder 98 between second bore 56 and counterbore 96 is cut at an angle 100 to a plane normal to the longitudinal axis of bore 56. The angle 100 is preferably approximately 200. Shoulder 98 is joined to counterbore 96 by a tapered surface 102 which is tapered at an angle 104 to the longitudinal axis of counterbore 56. The angle 104 is preferably approximately 150. This construction of the counterbore 96 is preferable for aiding expandable retaining ring 94 in locking itself in counterbore 96.

As shown in Fig. 2C a removable knock-out plug 106 is engaged with and blocks hole 50 in the wall of mandrel 1 8. Knock-out plug 106 includes a tubular portion 108 having external threads 110 engaging said hole 50. Knock-out plug 106 also includes an extension 112 projecting radially into said interior 28 of mandrel 18. Knock-out plug 106 is constructed so that extension 112 may be broken or sheared off by a force from above.

The extension 1 2 is generally sheared off by pumping a cement plug down the interior of casing 12 and mandrel 1 8 or by running some other tool on a drill string down the casing 12 so as to strike knock-out plug 106 and shear off extension 112.

The knock-out plug 106 is so constructed that when extension 112 is sheared off it shears at a point within hole 50 so that there are no sharp edges projecting into interior 28 of mandrel 1 8 which might cut swab cups or the like being moved through casing 12.

When extension 112 is sheared off of knockout plug 106 this allows fluid communication between interior 28 and the inlet 26 of valve body 48 through the tubular portion 50 of knock-out plug 106.

The valve means 24 is so constructed that it may be very easily assembled with the mandrel 1 8. The valve means includes the cylindrical valve body 48 having the first end 54 and a second end 114.

A constant diameter cylindrical inner surface 116 of valve body 48 interconnects said first and second ends 54 and 114, respectively. The cylindrical outer surface 40 of mandrel 1 8 is closely received within said cylindrical inner surface 116 of valve body 48 and such cylindrical outer surface 40 of mandrel 1 8 extends past each of said first and second ends 54 and 114 of said valve body 48.

The outlet 30 of valve means 24 includes an annular axially extending groove 11 8 disposed in said second end 114 of valve body 48. Axially extended groove 11 8 defines radially inner and outer axially extending concentric tongues 1 20 and 122, respectively.

A portion 124 of lower annular packer shoe 38 adjacent said second end 11 4 of valve body 48 is radially spaced from said outer cylindrical surface 40 of mandrel 1 8 forming an annular passage 126 communicating with said annular groove 11 8 of said outlet 30 of said valve means 24.

The inner tongue 120 of first end 114 of valve body 48 is welded to said radially outer surface 40 of mandrel 1 8 as indicated at 128. Radially outer tongue 122 of first end 114 of valve body 48 is welded to said lower annular packer shoe 38 as indicated at 1 30. This construction provides the strength of full 1/4 inch fillet welds at 128 and 130, while also providing a large flow area by the intersection of groove 118 and annular passage 126.

First- end 54 of valve body 48 is welded to outer cylindrical surface 40 of mandrel 1 8 as indicated at 132. First end 54 of valve body 48 engages a lower backup ring 1 34 which itself is welded to mandrel 18 at 136.

An upper portion of lower backup ring 134 is radially spaced from outer surface 40 of mandrel 18 so as to define an annular space 138 which communicates with first end 54 of valve body 48 and with first and second bores 52 and 56. A relief bore 140 communicates annular space 138 with the cavity 1 6 between mandrel 1 8 and borehole 14.

The modular construction of the inflatable packer assembly 10 described above allows a variety of different weight ranges of the packer assembly 10 to be constructed using the same packer or bladder means 20 and the same valve means 24. All that is required to vary the design capacity of the inflatable packer assembly 10 is to vary the weight of the mandrel 1 8. This greatly reduces the cost of manufacture of the inflatable packer assembly 10 as compared to prior art designs wherein the valve means was constructed integrally with a portion of the casing or of the mandrel.

The operation of the inflatable packer assembly 10 is as follows. The inflatable packer assembly 10 is constructed and assembled as illustrated in Figs. 1 and 4 with the first and second pistons 76 and 84 in their first positions with the shear pins in place. The inflatable packer assembly 10 is then attached as an integral part of casing 12 as illustrated in Fig. 1 and is lowered into the borehole 14 until the packer 20 is adjacent the location where it is desired to seal the cavity 1 6 between the casing 12 and the borehole 14.

To prevent premature inflation of the packer or bladder means 20 while running the casing 12 into the hole 14, the hole 50 and inlet 26 are blocked by the knock-out plug 106.

Once the casing is properly positioned and it is desired to inflate the packer 20, the extension 112 is sheared off of the knock-out plug 106 to allow fluid from interior 28 of the mandrel 18 to enter inlet 26.

In a preferred embodiment of the present invention, once the knock-out plug 106 is removed the first piston 76 will remain in its first position until a pressure differential across that first piston, i.e. a pressure differential between the interior 28 of mandrel 18 and the cavity 16, reaches a first predetermined level at which the shear pin 82 is designed to shear. In a preferred embodiment this first level equals a differential pressure of 1480 psi (+150 psi for 99% probability).

When the pressure differential reaches that first level the shear pin 82 shears and allows first piston 84 to move to its second position so that fluid may flow through first port means 58, second bore 56, and second port means 66 to outlet 30. The fluid flows through outlet 30, then through annular passage 126, and then through the narrow annular clearance 142, between lower packer shoe 38 and outer surface 40 of mandrel 18, to the annular space 22 between bladder means 20 and mandrel 18.

When the fluid under pressure from the interior 28 of mandrel 18 flows into the annular space 22 it inflates the bladder 20 from the uninflated position shown in Figs. 2A and 2B to the inflated position shown in Fig. 1.

The annular space 22 will remain in fluid communication with the interior 28 of mandrel 18 until the pressure differential between the interior 28 and the cavity 1 6 reaches a second level at which the shear pin of second piston 84 is designed to shear and allow the second piston 84 to move to its second permanently locked position. When second piston 84 is in its second position the second port means 66 is permanently isolated from the interior 28 of mandrel 1 8 so that the bladder means 20 remains permanently inflated. The second level, at which the shear pin of the second piston shears, is higher than said first level of said pressure differential, and in a preferred embodiment of the present invention said second level is equal to 2000 psi (i200 psi for 99% probability).

An important feature of the present embodiment is that when the second valve 84 moves from its first position to its second position, to block second port means 66, there is no loss of fluid from annular space 22. The volume of second port means 66 when second piston 84 is in the first position of Fig. 4 is equal to a volume of said second port means 66 when second piston 84 is in its second position blocking port means 66. Automatic control valves for inflatable packers of the prior art have included means for automatically shutting off the supply of fluid to the inflatable packer, but those prior art control valve means have typically included a structure such as that of U.S. Patent No.

3,524,503 to Baker having a sliding piston with one end in fluid communication with the annular space 22 so that when a certain pressure is reached within that annular space 22 the piston is moved to a closed position. However with such prior art designs the movement of the piston to the second closed position causes that end of the piston in communication with the annular space 22 to be moved away therefrom so as to allow a smail amount of fluid to be lost from the annular space 22.

In the applications of the present invention where the fluid is typically a substantially incompressible fluid such as water or drilling mud and is under very high pressure in a deep oil well, the loss of even a very small amount of fluid, e.g.

one cubic centimeter, can create a considerable loss of pressure within the annular space 22.

Since the ability of the inflated packer 20 to support a column of fluid above packer20 within the annular cavity 1 6 is directly related to the inflation pressure of the annular packer 20, this loss of pressure within the annular space 22 directly results in a lower design capacity of the inflatable packer.

Claims (6)

Claims

1. An inflatable packer assembly, comprising a cylindrical mandrel, a packer disposed about an outer cylindrical surface of said mandrel, said packer including an inflatable element, and valve means, connected to said packer, for directing fluid under pressure to said packer to inflate said element, said valve means including a cylindrical valve body having first and second ends with a cylindrical inner surface connecting said first and second ends, said cylindrical outer surface of said mandrel being closely received within said cylindrical inner surface of said valve means and said cylindrical outer surface of said mandrel extending past each of said first and second ends of said valve means.

2. An assembly as claimed in claim 1, wherein said cylindrical inner surface of said valve means has a constant internal diameter.

3. An assembly as claimed in claim 1 or 2, wherein said packer further includes an annular shoe connected to an end of said inflatable element and said valve means further includes an inlet communicating with an interior of said mandrel, an outlet disposed in one of said ends of said valve body, said one end of said valve body being connected to said annular shoe of said packer, and a port, disposed in said valve body, connecting said inlet and outlet.

4. An assembly as claimed in claim 3, wherein said outlet of said valve means includes an annular axially extending groove disposed in said one end of said valve body, said groove defining radially inner and outer axially extending concentric tongues.

5. An assembly as claimed in claim 4, wherein a portion of said annular shoe adjacent said one end of said valve body is radially spaced from said outer cylindrical surface of said mandrel, forming an annular passage between said shoe and said mandrel, said annular passage communicating with said annular groove of said outlet of said valve means.

6. An assembly as claimed in claim 5, wherein said radially inner tongue of said one end of said valve body is welded to said radially outer surface of said mandrel and said radially outer tongue of said one end of said valve body is welded to said annular shoe of said packer.