FIELD OF THE INVENTION

This invention generally relates to an inflatable packer and control valve for use on a casing in the annular space between the casing and a well or borehole for sealing off said annular space. The present invention relates to both single use and reusable inflatable packers.

More particularly, the present invention relates to an inflatable packer and control valve for use on the outside of a casing, as used in wells and boreholes, and is operated by differential pressure against shear pins and changes operating conditions by axial displacement of generally cylindrical sleeve valve members. The control valve uses relatively large annular flow passageways for the flow of inflation fluid, especially cementitious slurries, to avoid blockage and allow reliable inflation and thus minimise the risk of under-inflation due to blockage of tubular passageways commonly used in prior art control valves. The control valve also uses a locking mechanism to ensure positive engagement of one of the sleeve valve members to ensure shut-in of the valve to maintain inflation of the inflatable packer.

As a proprietary term the inflatable packer and control valve of the present invention may be referred to as an "inflatable casing packer". This is of the same general kind of packers as "external casing packers" and "casing inflation packers".

The inflatable packer and control valve of the present invention shall hereinafter also be referred to more simply as a "packer and valve assembly".

The packer and valve assembly of the present invention is of the type that does not require manipulation of the casing for its activation, nor does it require an activation tool to be run down the casing to achieve activation. The packer and valve assembly of the present invention requires the use of cementing plugs in operative association with the control valve to effect cementing of the annular space.

The packer and valve assembly of the present invention is of the type that is activated through various modes of operation by changes in pressure differentials within the valve.

TERMINOLOGY

In the fields of well and borehole technology there are a diversity of terminologies used. So as to avoid confusion the following specific terminology is used in the context of the present invention: • "Annular" in the context of the present invention is a term used to refer to the space between two generally coaxial hollow bodies. In the context of the control valve of the present invention "annular" is taken to mean generally annular and may include a situation where part of an annular space is completely annular and another part of the annular space may not be completely annular.

• "Casing" is a term used to refer to any type of pipe casing or the like, used in oil and gas or water well drilling operations. The term "well casing" is often used when referring to casing.

• "Cementing plug" is a term used to refer to a drillable plug often referred to as a wiper, wiper plug or pig.

• "Cementitious slurry" is a term used to refer to any type of curable or settable slurry that may be used in downhole operations, and includes compositions such as cement slurry, curable polymer, curable plastic and / or epoxy or the like.

• "Elastomeric packer element" or "packer element" is a term used to refer to any type of generally tubular expandable element that may be inflated by settable or non- settable slurry, liquid or gas, usually to fill an annular cavity.

• "Inflatable packer" is a term used to refer to an entire packer assembly capable of inflation by settable or non-settable slurry, liquid or gas, and includes an elastomeric packer element.

· "Open hole" is a term used to refer to a well hole or borehole that has not been or is yet to be lined with a casing and cementitious material between the casing and the open hole.

• "Open hole annulus" is as term used to refer to the annular space between the

casing and the open hole.

· "Well fluid" is a term used to refer to any type of slurry, liquid or gas capable of use in inflating an inflatable packer, and includes water, brine, gas (such as nitrogen), resin, gel, cement, drilling mud or the like.

BACKGROUND TO THE INVENTION

In the field of inflatable packers it is well known to use 3 stage valves, as typified by US Patent 4,420,159 for a packer valve arrangement. The first stage of these kinds of valve inhibits inadvertent inflation of the packer during running into the open hole. The second stage of the valve is a backup for the first. The third stage of the valve locks the pressure in the packer once it is fully inflated so that pressure can be removed from the casing string to prepare for other operations. These kinds of valves have narrow diameter ports and flow passages leading from the bore of the well casing to the inflatable packer. The narrow diameter ports and flow passages and their associated valve components are prone to blockage with particles commonly earned in cementitious slurry setting fluid used to inflate the packers. These blockages lead to underinflated packers and result in well annulus cement leaking into the production zone and compromising the operation of the well with severe financial consequences.

Another problem with these kinds of 3 stage valves is that some inflation fluid pumped at high velocity, particularly cementitious materials and drilling mud, tend to rapidly erode metal used in control valves. In the case of narrow diameter ports and flow passages this has the tendency of preventing conventional control valves from functioning correctly. Another kind of control valve for inflatable packers is shown in US Patent 4,941 ,534 which uses an upper sleeve valve held against a spring, to allow the annular space to be filled with cementitious fluid once the packer is inflated, and an intermediate and a lower sleeve valve operating against shear pins and involved in the inflation and shut-in of the packer. The lower sleeve valve has a C-ring arranged to contract radially to fit into a groove to lock the pressure in the packer. The main problem of '534 is that rapid pressurisation of the valve could result in the lower sleeve valve moving downwardly at such a rate that the C-ring does not contract into the groove. Then depressurisation of the valve could cause the lower sleeve valve to move upwardly at such a rate that the C-ring again fails to seat in the groove. The result is that the inflatable packer is not set in properly and can easily deflate and thereby fail to seal off the annular space. That is, '534 assumes that an inflation pressure spike guarantees shut-in of the packer, whereas in truth it does not.

The inflatable packer and control valve of the present invention has the advantage of relatively large flow passages that are not prone to blockage or erosion from inflation and / or setting fluid, and includes a locking mechanism to ensure shut-in of the valve and is therefore more reliable that prior art valve operated inflatable packers.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide an inflatable packer and control valve having large flow passageways for the flow of inflation fluid, especially cementitious slurries, to avoid blockage and erosion, and including means to ensure shut-in of the valve to allow more reliable inflation.

In accordance with one aspect of the present invention, there is provided an inflatable packer and control valve for use in sealing an annular space between a casing and a borehole surrounding the casing, the inflatable packer and control valve including: a mandrel with threaded ends for connecting into the casing, the mandrel having a plurality of radial inlet ports; an inflatable packer disposed on the outer curved surface of the mandrel, the inflatable packer having an annular inlet port, and the inflatable packer being inflatable with inflation fluid received via the annular inlet port from said radial inlet ports, the packer once inflated sealing off the said annular space; and, a control valve including: a housing fixed and sealed onto the outer curved surface of the mandrel; a substantially annular flow passage defined within the housing for communicating inflation fluid from the said plurality of radial inlet ports to the annular inlet port of the inflatable packer, the annular flow passage being generally coaxial with the mandrel; a first and a second sleeve valve disposed in the annular flow passage for respectively allowing flow of inflation fluid from the plurality of radial inlet ports to the annular inlet port of the inflatable packer and blocking flow of inflation fluid out of the annular inlet port of the inflatable packer subject to respective first and second pressure differentials across said first and second sleeve valves, the second pressure differential being higher than the first pressure differential; and a one way locking means in operative association with the second sleeve valve, the locking means engaging with the second sleeve valve for preventing flow of inflation fluid into and out of the annular inlet port of the inflatable packer once the second predetermined pressure differential has been exceeded.

Preferably, the one way locking means is a ratchet type mechanism that allows movement of the second sleeve valve in the annular flow passage in one direction only, so as to be able to prevent further inflation of the inflatable packer and to inhibit deflation thereof. Also, the ratchet function positively prevents release of the second sleeve valve and so provides an accurate means for shutting inflation fluids into the inflatable packer.

In the context of the present invention "one way" in relation to the locking means refers to allowing motion only in one direction and preventing motion in the return direction.

Also, the control valve could also be mounted either above or below the inflatable packer. Typically, the inflation fluid is cementitious material, such as, for example, settable slurry and may include cement. The inflation fluid could also be non-settable fluid, such as, for example, water, brine, gas (such as nitrogen), resin, gel, drilling mud or the like. BRIEF DESCRIPTION OF THE DRAWINGS

The nature of the invention will be better understood from the following description of a specific embodiment of the present invention, given by way of example only, with reference to the accompanying drawings in which: Figure 1 is a longitudinal cross-section of a single use inflatable packer and control valve in accordance with the present invention;

Figures 2a and 2b are longitudinal cross-sections of the packer and valve assembly of Figure 1a showing greater detail of its mandrel, control valve and inflatable packer, with Figure 2a showing the control valve and Figure 2b showing a sliding end of the inflatable packer, the labels B of the two Figures showing that Figure 2b is an extension of Figure 2a;

Figure 3 is a longitudinal cross-section of the mandrel of the packer and valve assembly of Figures 2a and 2b in greater detail;

Figures 4a to 4c are part longitudinal cross-sections of a control valve of the packer and valve assembly of Figure 1, with centrelines A and B common to the drawings such that overlapping them endwise produces the entire control valve;

Figures 5a to 5c are longitudinal cross-sections of a control valve of the packer and valve assembly of Figure 1 , the drawings respectively showing the control valve firstly, prior to setting in a well or borehole, secondly in an inflation mode of operation, and thirdly in a locked mode of operation; and,

Figure 6 is a longitudinal cross-section of a sliding end of an inflatable packer of the packer and valve assembly of Figure 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the drawings there is shown a single use inflatable packer and control valve 10, which is conveniently hereinafter referred to as the packer and valve assembly 10.

Particularly as shown in Figures 1 and 2 the packer and valve assembly 10 includes a mandrel 12, an inflatable packer 14 and a control valve 16. The inflatable packer 14 and the control valve 16 are located on the outer curved surface of the mandrel 12. The packer and valve assembly 10 is inflatable to seal off an open hole annulus 20 between the mandrel 12 and an open hole 21 of a well or borehole.

The packer and valve assembly 10 of the present invention is made from metals materials and elastomeric materials. The metals material components of the packer and valve assembly 10 are typically relatively high tensile metals materials, such as, high carbon steel and / or alloy steel. The metals materials are typically required to withstand high shear, compression and tensile stresses as well as potentially highly corrosive environments, as well as the erosive effects of cementitious fluid and / or drilling mud. The elastomeric materials are typically rubber as commonly used in inflatable packers. The packer and valve assembly 10 is predominantly made from metals materials, except for elastomeric materials seals and an inflatable packer element, as described in detail hereinafter.

The mandrel 12 is intended to have its upper threaded end 22a and lower threaded end 22b, threaded into a string of casing 23, particularly as shown in Figures 1 a and 1 b, with casing collars 23a. The casing 23 extends upwardly from the upper end 22a of the mandrel 12 to an operations rig (not shown) at the surface above the open hole 21. The casing 23 also extends downwardly from the lower end 22b of the mandrel 12 to other tools conventionally used in borehole applications and typically located adjacent the bottom of the open hole 21.

The mandrel 12 is preferably made from a piece of the casing 23 so as to have the same cross-sectional dimensions and mechanical characteristics. It is important that the mandrel 12 and the casing 23 be similar or the same materials (that is non-dissimilar materials) so as to avoid electrolysis between them and hence corrosion. The internal bore of the mandrel 12 is flush with the internal bore of the casing 23 so that the packer and valve assembly 10 does not produce a constriction to flow of well products. The mandrel 12 has a series of external annular grooves 24 to 28 dimensioned to receive respective elastomeric seals conveniently in the form of o-ring seals 24a to 28a (particularly as shown in Figures 3 and 5a). The mandrel 2 also has an external annular groove 29 dimensioned to receive a D-seal 29a, or the like. The seals 24a to 29a seal against components of the control valve 16. The seal 29a is designed so as to not be susceptible to "wash-out" by high velocity inflation fluid flowing over it and hence care is required in the selection of this seal. We have found so called "D-seals" (which are generally "D" shaped in cross-section and solid) to be suitable since they conform closely to the cross-sectional shape of the annular groove 29.

The mandrel 12 has an external annular recess 30 disposed on its outer curved surface to receive a retaining ring 32 to key the control valve 16 onto the mandrel 12, thereby fixing the control valve 16 to the mandrel 12. The annular recess 30 and retaining ring 32 have sufficient width to ensure that the retaining ring does not shear under the normal operating pressures of the packer and valve assembly 10. The annular recess 30 is sufficiently shallow so as to not unduly weaken the mandrel 12 and thereby avoid failure of the mandrel 12 in the region of the annular recess 30. The retaining ring 32 is disposed towards an upper end 34 of the control valve 16, with a lower end 36 of the control valve 16 being disposed adjacent the inflatable packer 14. Typically the retaining ring 32 is made of the same metals materials as the other components of the control valve 16. That is to say it is not necessary for the retaining ring 32 to be made of spring steel or other resilient metals material.

The mandrel 12 also has a plurality of radial inlet ports 38, only one of which is shown in the drawings, disposed for communicating inflation fluid from the interior of the casing 23 to the control valve 16 and thereby to the inflatable packer 14. Typically, there are three ports 38. Typically, the inlet ports 38 are disposed evenly around the circumference of the mandrel 12 and have axes that are coplanar and at 90 degrees to the axis of the mandrel 12.

The inflatable packer 14, for the purposes of the present invention, may be of conventional construction (see for example US Patent 4,310,161 assigned to Halliburton Services and US Patent 4,253,676 assigned to Halliburton Company). Typically, the inflatable packer 14 has a packer ferrule 40 at its upper end 42, an inflatable packer element 44, and a sliding end ferrule 46 at its lower end 48. The packer ferrule 40 and the sliding end 46 are fixed to the packer element 44 in known manner.

The packer ferrule 40 is threadedly connected to the lower end 36 of the control valve 16 and thereby is fixed to the mandrel 12.

The packer ferrule 40 also has an annular inlet 50, being a narrow clearance formed between the packer ferrule 40 and the mandrel 12, for receiving inflation fluid from the control valve 16. The annular inlet 50 also extends part way into the packer element 44. The cross-sectional area of the annular inlet 50 is preferably greater than the cross-sectional area of the inlet ports 38.

The packer element 44 is cylindrical and is formed of expandable elastomeric material reinforced with cables or the like as is well known in the art. The packer element 44 is capable of expanding under the action of the force of the inflation fluid to expand from a non- inflated condition wherein, the diameter of the exterior curved surface of the packer element 44 is not greater than that of the sliding end 46, to an inflated condition wherein the external curved surface of the packer element 44 expands to meet the internal curved surface of the open hole 21 (as shown by ghosted lines in Figure 1). The elastomeric material of the packer element 44 is capable of expansion against the non-expandable constriction of the cables. As is known in the art, the cables are oriented so as to permit limited expansion of the elastomeric material.

The packer element 44 may be inflated by any fluid commonly used for the purpose, inciuding water, brine, gas (such as nitrogen), resin, gel, cement, drilling mud or the like.

The sliding end ferrule 46 is cylindrical in shape and slides on the external curved surface of the mandrel 12. The sliding end 46, particularly as shown in Figures 2b and 6, also includes a radially disposed priming port 60 and plug 60a for priming the packer and valve assembly 10 with inhibitor or the like prior to running into the open hole 21 so as to avoid corrosion and to displace any air that may otherwise fill the sliding end ferrule 46 and the annular space between the packer element 44 and the mandrel 12 and lead to unpredictable behaviour. The sliding end ferrule 46 also has a channel 62 on its internal curved surface and arranged in communication with the priming port 60. The channel 62 is enclosed at its lower end by a hydraulic seal 64 to inhibit liquids from exiting the packer and valve assembly 10 through the sliding end 46. The sliding end ferrule 46 may also have a bearing 66 at its upper end. The bearing 66 is conveniently made of PTFE or the like.

It is to be understood that the lower end ferrule 46 could be fixed to the mandrel 12 rather than being slideable upon the mandrel 12. A fixed end ferrule 46 requires a suitably designed packer element 44 that can expand without shortening its length.

The control valve 16, particularly as shown in Figures 2a, 4a to 4c and 5a to 5c, includes a valve retaining sub 80, at its upper end 34, a top valve sub 82, an inflation preventer valve 84 (also referred to herein as the "first sleeve valve"), a lower valve sub 86, an inflation shut- in valve 88 (also referred to herein as the "second sleeve valve"), a valve ratchet ring 90 (also referred to herein as the "locking means"), a valve packer crossover 92 and a plurality of shear-off plugs or "carrots" 94, also sometimes referred to as knock-off pins or break-off rods.

The valve retaining sub 80 is generally cylindrical with an internal curved surface

dimensioned to closely mate with the O-ring seals 24a and 25a of the mandrel 12. The valve retaining sub 80 has an internal annular groove 100 dimensioned to receive the valve retaining ring 32 to fix the control valve 16 to the outer curved surface of the mandrel 26. The valve retaining ring 32 is made of resilient material, such as, for example, metals material, and typically has an outside diameter that is larger than the internal diameter of the valve retaining sub 80. Hence, the valve retaining ring 32 must be compressed in order to fit into the bore of the valve retaining sub 80 and thereby into the groove 100 during assembly. Preferably, the outside diameter of the valve retaining ring 32 is greater than the diameter of the base of the groove 100 so that the ring 32 sits snugly in the groove 100 prior to assembly of the valve retaining sub 80 on the mandrel 12. The valve retaining ring 32 has an open section of sufficient dimension to allow compression of the ring 32 to fit inside the bore of the valve retaining sub 80 (that is the ring 32 is not closed). The valve retaining sub 80 also has a plurality of grub screws 101 received in threaded holes 102. The grub screws are forced against the outer curved surface of the ring 32 to bend it into the external annular recess 30 of the mandrel 12 from the base of the groove 100. The ring 32 is thicker than the depth of the recess 30 and so remains partway in the groove 100 thus fixing the valve retaining sub 80 to the mandrel 12.

Typically, the retaining ring 32 is tightened into the annular recess 30 by first tightening grub screws 101 intermediate of the length of the retaining ring 32, followed by grub screws 101 progressively towards the free ends of the retaining ring 32. Alternatively, tightening of the grub screws 101 can commence at one end of the retaining ring 32 and progressively move towards the other end.

As an option to ensure fixation of the valve retaining sub 80 to the mandrel 12 epoxy or the like setting agent may be forced into the space that remains between the outer curved surface of the valve retaining ring 32 and the base of the internal annular groove 100. For this purpose a port (not shown) is typically provided in the wall of the valve retaining sub 80 between two of the threaded holes 102. The epoxy has the benefit of avoiding loosening of the valve retaining sub 80 in transport and during use. In some situations, however, it is not viable or appropriate to use a setting agent as a backup to the grub screws 101.

The valve retaining sub 80 also has an externally threaded lower end 104 with a groove 106 and an o-ring seal 108 at its base for sealing against the top valve sub 82. The top valve sub 82 is generally cylindrical and forms an annular cavity 118 with the outer curved surface of the mandrel 12. This cavity 118 is referred to as a lift cavity 118 since it is associated with lifting the inflation preventer valve 84, as described hereinafter. The top valve sub 82 has an internally threaded upper end 120 that engages with the externally threaded lower end 104 of the valve retaining sub 80 and terminates at its free end at an O- ring sealing area 122 for sealing against the O-ring seal 106 of the valve retaining sub 80.

The top valve sub 82 also has an upper pressure equalisation port 124 disposed adjacent the inner extent of the upper end 120. The pressure equalisation port 124 allows equalisation of pressure across the inflation preventer valve 84 (between the control valve 16 and the open hole 21) as the packer and valve assembly 10 is lowered into the open hole 21 and during which time the packer and valve assembly 10 may experience abnormal changes in operating pressure. The port 124 also allows upward sliding movement of the inflation preventer valve 84 in the lift cavity 118 by avoiding a fluid lock that could otherwise form as a result of the O-ring seals 25a, 108, 24a and 178a.

The internally threaded upper end 120 of the top valve sub 80 threadedly engages with the externally threaded lower end 104 of the valve retaining sub 80 and is thereby fixed to the mandrel 12.

The top valve sub 82 also has a plurality of threaded holes 126 for receiving one or more shear pins 126a each of which has a pin 126b that engages with the inflation preventer valve 84 to inhibit its rise in the lift cavity 118 for all pressures below a threshold pressure differential across the inflation preventer valve 84 (also referred to herein as the "first predetermined pressure differential"), and above which pressure the pins 126b shear to release the inflation preventer valve 84. Typically, the shear pins 126a are made from relatively soft and shearable material, such as, for example, brass. Typically, the shear pins 126a shear at pressure differentials between 1 and 50 MPa. The number of shear pins 126a used is increased to cope with situations where higher operating pressure differentials are likely to occur. Typically these pressure differentials are measured and the number of shear pins 126a changed according to the expected operating pressure prior to lowering the packer and valve assembly 10 into the open hole 21. Blank plugs without the pins 126b are inserted into the holes 126 that do not require shear pins 126a in a particular instance of use of the packer and valve assembly 10. Typically, 4 or less shear pins 126a are required. These shear pins 126a prevent sliding movement of the inflation preventer valve 84 for all pressures below the first predetermined pressure differential and thereby prevent premature inflation of the inflatable packer 14. That is, the first pressure differential is set to be greater than the pressure differentials expected to be experienced during running in of the packer and valve assembly 10 into the open hole 21.

The top valve sub 82 further has an externally threaded lower end 130, threadedly engaged with the lower valve sub 86, and the lower end 130 having a groove 132 and an o-ring seal 134 at its base for sealing against the lower valve sub 86.

Proximate the lower end 130 of the top valve sub 82 is a top priming port 133 having a tapered thread for receiving a pressure plug 133a. The priming ports 60 and 133 allow for the packer and valve assembly 10 to be primed with inhibitor or the like fluid to avoid corrosion of components of the control valve 16. The inhibitor is also used to expel excess air from the packer and valve assembly 10 which may otherwise behave unpredictably at high operating pressures.

At an upper end of the inner curved surface of the lower end 130 of the top valve sub 82 is a series of flutes 136 disposed to allow flow of inflation fluid from the inlet ports 38 downwardly to an upper annular passageway 140. The inner curved surface defined by spaces between the flutes 136 defines a fluted annular wall 138 which has a small clearance to the outer curved surface of the mandrel 12. The flutes 136 and the outer curved surface of the mandrel 12 form a series of passageways whose combined cross-sectional area is larger than that of the inlet ports 38 which feed inflation fluid from the bore of the casing 23 to inflatable packer 14. Typically, the flutes 136 are semicircular in cross-section and their longitudinal axes are substantially parallel to the axis of the mandrel 12. The top valve sub 82 also has a shoulder 150 defined by the upper end of the fluted annular wall 138. The shoulder 150 supports a lower end 160 of the inflation preventer valve 84.

The inflation preventer valve 84 is substantially cylindrical with an upper end 162 opposite its lower end 160. The inflation preventer valve 84 is in the form of a sleeve valve mounted upon the mandrel 12. The inflation preventer valve 84 defines an annular space 163 with the lower end 104 of the valve retaining sub 80 and into which the pressure equalisation port 124 reaches from the open hole annulus 20 (also referred to herein as the "annular space") above the inflatable packer 14. The inflation preventer valve 84 also has a plurality of radially disposed ports 164 disposable to communicate inflation fluid from the plurality of inlet ports 38 to the lift cavity 118. The ports 164 are situated towards the lower end 160. Typically, there are about 8 ports 164 with a combined cross sectional area that is greater than that of the radial inlet ports 38.

The inflation preventer valve 84 also includes a series of blind holes 170 arranged on its outer curved surface to marry with the shear pin holes 126 so as to receive the pins 126b to fix the inflation preventer valve 84 to the top valve sub 82 for all pressure differentials of operation below the pressure differential that causes the pins 162b to shear off the shear pins 126a (the first predetermined pressure differential).

The inflation valve preventer 84 also has two annular channels 172 and 174 located on its inner and outer curved surfaces respectively, and each surrounding opposite ends of the ports 164. The channels 172 and 174 act as manifolds to enable the ports 164 to communicate with each other and all of the radial inlet ports 38 and the inflation cavity 118. Typically, the cross-sectional area of the ports 164 is greater than that of the inlet ports 38 so as to not inhibit the flow of inflation fluid in the control valve 16. The annular channel 174 is wider than the annular channel 172 and has its upper reaches disposed closer to the upper end 162 than those of the annular channel 172. As a result inflation fluid flowing through the ports 38 urges the inflation preventer valve 84 upwardly toward the valve retaining sub 80 and, when the pressure differential of the inflation fluid across the inflation preventer valve 84 (from the lift cavity 118 to the cavity 163) is sufficient, causes the shear pins 126a to shear and allow the inflation preventer valve 84 to slide upwardly with respect to the top valve sub 82 towards the valve retaining sub 80. The inflation preventer valve 84 also has two circumferential grooves 176 and 78 on its outer curved surface spanning the annular channel 174, and with corresponding O-ring seals 176a and 178a. The seals 176a and 178a allow pressure build up in the lift cavity 118 defined between the channel 174 and the inner circumferential surface of the top valve sub 82. The lift cavity 118 has an end wall 180, conveniently defined by one end of the channel 174. The end wall 180 is disposed substantially parallel to the pins 126b of the shear pins 126a. The area of the end wall 180 is chosen so as to provide sufficient force (force = pressure x area) against the shear pins 126a for reliable shearing thereof at the desired operating pressure differential across the inflation preventer valve 84. The combination of the upper pressure equalisation port 124, the annular space 163 and the O-ring seals 176a and 178a allow there to be a pressure differential across the inflation preventer valve 84 - the pressure differential being from the bore of the mandrel 12 (and thus from the bore of the casing 23), through the inlet ports 38, through the ports 164 into the lift cavity 118 and across the inflation preventer valve 84 to the open hole annulus 20 above the inflatable packer 14.

The inflation preventer valve 84 is moveable against the shear pins 126a from a closed condition, wherein the ports 164 communicate with the inlet ports 38 and the lower end 160 rests against the shoulder 150 of the fluted annular wall 138, to an open condition, wherein the upper end 162 of the inflation preventer valve 84 bears against the lower end 104 of the valve retaining sub 80 and the lower end 160 of the inflation preventer valve 84 moves past the inlet ports 38 to allow further inflation fluid to flow from the inlet ports 38 downwards towards the inflatable packer 14.

It is to be noted that the pins 126b of the shear pings 126a remain encapsulated in the blind holes 170 after shearing off the shear pins 126a. This avoids the possibility of the pins 126b fouling with other moving components of the control valve 16.

Also, it is preferred that a D-seal 29a, or the like, be used on the downstream side of the inlet ports 38 so that inrush and flow of high velocity inflation fluid does not unseat the seal and lift it out of the annular groove 29. The base of the D-seal 29a substantially matches the profile of the annular groove 29 to assist in inhibiting lift out of the seal by the inflation fluid. Also, D-seals have a much higher resistance to stretch than is conventionally the case with O-ring seals. The D-seal 29a is required to seal whilst the inflation preventer valve 84 is in the closed condition and thereafter is not required.

Also, the D-seal 29a is located just above the shoulder 150 of the fluted collar 138. It is to be noted that the flutes 136 in the fluted collar 138 are dimensioned so that even if the D-seal 29a is washed out of its annular groove 29 and lands on the shoulder 150 there is sufficient clearance for good flow of inflation fluid to the inflatable packer 1 and thereby to avoid under-inflation of the packer 14.

The lower valve sub 86 is generally similar in construction, shape and configuration to the top valve sub 82, although with some important differences as described hereinafter.

The lower valve sub 86 is generally cylindrical and has an internally threaded upper end 190 with an O-ring sealing area 192. The internally threaded upper end 190 is threaded onto the externally threaded lower end 130 of the top valve sub 82 and thereby to the mandrel 12. The O-ring sealing area 192 seals against the O-ring 134 to maintain a fluid tight connection between the upper valve sub 82 and the lower valve sub 86.

Adjacent the threaded end 190 the lower valve sub 86 has a plurality of circumferentially disposed threaded holes 194 each capable of receiving a shear pin 196 with pins 196a. Typically, there are 8 shear pins 196. The number of shear pins 196 is varied depending upon the operating pressure differential of the control valve 16 (and hence the depth of the well). When less than, say, 8 shear pins 96 are to be used the remaining holes 194 receive blanks which can be made from the same material as the shear pins 196.

It is preferred that the shear pins 196 be of the same size, shape, material and construction as the shear pins 126a - so as to avoid the possibility of inserting the wrong shear pins into the wrong holes.

The lower valve sub 86 also has a lower pressure equalisation port 198 disposed from the open hole annulus 20 to the upper annular passageway 140. The lower pressure equalisation port 198 is described in more detail hereinafter.

The lower valve sub 86 further has an externally threaded lower end 210 with an annular groove 212 at its base and receiving an O-ring seal 214.

The entire extent of the lower valve sub 86 is in spaced relation to the mandrel 12 and contains within its bounds the majority of the inflation shut-in valve 88.

The inflation shut-in valve 88 is substantially cylindrical and is in the form of a sleeve valve mounted upon the mandrel 12. The inflation shut-in valve 88 has a base ring 220 which rests upon the O-ring seals 27a and 28a in sliding manner and is slideable from a first, open condition, wherein the shear pins 1 6 are whole, to a second, closed condition, wherein the pins 196a of the shear pins 196 have sheared off. The base ring 220 has a pair of annular grooves 221 on its outer curved surface with corresponding D-seals 221a, or the like. The D- seals 221a engage with and seal against the inner curved surface of the lower valve sub 88 when in the closed condition, and when the inflation shut-in valve 88 is in the open condition the D-seals do not engage with the lower valve sub 86. D-seals have been chosen for this application so that high velocity inflation fluid does not unseat the seals - as would be the case if O-ring seals were used in their place. An upper end 224 of the inflation shut-in valve 88 has an annular groove 226 disposed on its outer curved surface, receiving an O-ring seal 226a for sealing against an inner curved surface of the lower valve sub 86. The upper end 224 bears against the lower end 130 of the upper valve sub 82 when in the open condition of operation of the inflation shut-in valve 88. The upper end 224 rests in the upper annular passageway 140. Located on the outer curved surface of the upper end 224 of the inflation shut-in valve 88 is a plurality of circumferentially disposed blind holes 230 disposed for receiving the pins 196a of the plurality of shear pins 196.

Formed between the inflation shut-in valve 88 and the lower valve sub 86 is a shutting-in cavity 236 into which the lower pressure equalisation port 198 reaches. The port 198 allows fluid to pass out of the cavity 236 when the inflation shut-in valve 88 moves from the open condition to the closed condition. Another annular groove 240 and associated O-ring seal 240a is provided on the outer curved surface of the inflation shut-in valve 88 opposite the cavity 236 from the O-ring 226a. The cavity 236 and the port 198 allow for equalisation of the pressure of the inflation shut-in valve 88 during running into the well and inflation of the packer 14. The combination of the lower pressure equalisation port 198, the shutting-in cavity 236 and the O-ring seals 226a and 240a allow there to be a pressure differential across the inflation shut-in valve 88 - the pressure differential being from the upper annular passageway 140 to the open hole annulus 20 above the inflatable packer 14. When the pressure differential cross the shut-in valve 88 exceeds the second predetermined pressure the pins 196a shear off the shear pins 196 and allow the shut-in valve 88 to move from its open condition to its closed condition to prevent any further inflation of the inflatable packer 14. Also, once the shear pins 196 shear off the cavity 236 closes off and the inflation shut-in valve 88 moves- to its full extent towards the sliding end 46. This provides an absolute limit to the movement of the valve 88 and ensures positive feedback that the valve 10 is in the shut- in mode of operation.

The upper annular passageway 140 includes an annular space 249 between the upper end 224 of the inflation shut-in valve 88 and the mandrel 12. The annular space 249 terminates at its lower end at a port 250 which leads from the inner curved surface to the outer curved surface of the inflation shut-in valve 88 just above the base ring 220. The outer curved surface of the base ring 220 and the inner curved surface of the lower valve sub 86 define an intermediate annular passageway 260 which terminates at its lower end at a port 266 which leads from the intermediate annular passageway 260 to the inner curved surface of the inflation shut-in valve 88 on the opposite end of the base ring 220 from the port 250. The inflation shut-in valve 88 has an annular groove 270 and an associated O- ring seal 270a on its outer curved surface adjacent the port 266. The O-ring seal 270a is disposed for sealing engagement with the inner curve surface of the lower valve sub 88 substantially opposite the O-ring seal 214.

The inflation shut-in valve 88 also has an annular male ratchet component 272 located proximate its lower end 274. The ratchet component 272 is conveniently made with saw tooth ridges 276 and an annular skirt 278, both disposed circumferentially around the outer curved surface of the inflation shut-in valve 88 proximate its lower end 274. The saw tooth ridges 276 are disposed so as to allow the inflation shut-in valve 88 to move in a direction towards the inflatable packer 14 but not in a direction away from the inflatable packer 14. That is, the saw tooth ridges 276 are disposed to allow the inflation shut-in valve 88 to ratchet in a direction towards the inflatable packer 14 but not in a direction away from the inflatable packer 14. The annular skirt 278 slides into and is received by the female ratchet ring 90.

The inflation shut-in valve 88 further has an annular groove 280 and an associated O-ring seal 280a located on its outer curved surface adjacent the lower end 274. The O-ring seal 280a is disposed to seal against an inner curved surface of the valve packer crossover 92 and is capable of sliding thereagainst.

The female ratchet ring 90 is generally cylindrical and is made in a manner to complement the shape of the saw tooth ridges 276 of the male ratchet component 272. Accordingly, the female ratchet ring 90 has saw tooth ridges 290 on its inner curved surface. The saw tooth ridges 290 are disposed to engage with the saw tooth ridges 276 of the inflation shut-in valve 88. The saw tooth ridges 290 are dimensioned so as to press against the annular skirt 278 when the inflation shut-in valve 88 is in the open condition. Particularly as shown in Figure 5c the two sets of saw tooth ridges 276 and 290 engage when the inflation shut-in valve 88 is in the closed condition.

The ratchet ring 90 conveniently has a cut or slit across its longitudinal width to allow it to expand as the two sets of saw tooth ridges 276 and 290 engage and ride over each other.

The valve packer crossover 92 has an internally threaded upper end 300 with an O-ring sealing area 302 outermost. The valve packer crossover 92 also has an externally threaded lower end 304 with an annular groove 306 and O-ring 306a at its base.

The upper end 300 threadedly engages with the lower threaded end 210 of the lower valve sub 86 and the lower end 304 threadedly engages with the sliding end 46 of the inflatable packer 14. The valve packer crossover 92 defines a cavity 308 with the lower end 210 of the lower valve sub 86 in which the female retaining ring 90 is housed and can expand radially outwardly as the male ratchet component 272 slides through it towards its closed condition.

The lower end 274 of the inflation shut-in valve 88 and the valve packer crossover 92 are in spaced relation to the mandrel 12 and define a lower annular passageway 310 which communicates from the port 266 to the annular inlet 50 of the sliding end 46 of the inflatable packer 14.

The combination of the upper annular passageway 140, the intermediate annular passageway 260 and the lower annular passageway 310 constitute a "generally annular flow passage" of the present invention, extending from the radial inlet ports 38 (and hence the bore of the casing 23) to the annular inlet 50 of the inflatable packer 14.

The shear-off plugs 94 are conveniently made from shearable plastics material, although they could be made of brass or other shearable metals materials. Each shear-off plug 94 has a threaded hollow head 320 for threaded engagement with one of the inlet ports 38 of the mandrel 12. Each plug 94 also has a hollow body 322 with a blank end 324. Each plug 94 further has an annular groove 326 adjacent the head 320. The groove 326 produces a weakness in the plug 94 at which it can readily shear when a cementing plug or wiper pig or the like is pumped down the core of the casing 23 and through the mandrel 12 for the purpose of shearing-off the plugs 94.

The operation of the packer and valve assembly 10 requires the use of a cementing plug (also called a wiper plug or pump-down plug) or ball (also called a pig) which is pumped into the casing 23 and settles on a float collar or the like situated in the casing 23 below the packer and valve assembly 10. Typically, the cementing plug is of the non-rotating type.

Once the packer and valve assembly 10 is inflated and the open hole annulus 20 is filled with cementitious slurry and set hard the plug is drilled out and the well is ready for testing prior to production. Detail of a typical setup and operation of cementing plugs is provided in

US Patent No 4,836,279 assigned to Halliburton Company and US Patent No 5,842,517 assigned to Davis-Lynch Inc.

It is to be noted that if a ball is to be used it is not suitable for shearing off the plugs 94 and in such case it is known to break off the plugs 94 before running the packer and valve assembly 10 into the open hole 21.

Typically, the pressure equalisation ports 124 and 196 are provided in pairs so as to avoid negative effects should a single port become blocked. USE

In use, the packer and valve assembly 10 of the present invention is most well suited to the challenges often encountered when using cementitious slurries, such as, for example, cement, to inflate inflatable packers to seal the open hole annulus 20. In some cases the cement inflated packer is used to support a column of cement to seal of the entire annular space 20 above the packer and valve assembly 10 to the surface to prevent fluids communicating along the well casing 23 at differing depths. In other cases the cement inflated packer is used for multiple zone isolation, such as, for example, as used in long horizontal wells, and does not support additional cement in the open hole annulus 20.

The packer and valve assembly 10 of the present invention is intended to be threaded into a string of casing 23 and lowered thereby into the open hole 21 with a drilling rig (in known manner) and inflated to seal off the open hole annulus 20. The packer and valve assembly 10, as shown in the accompanying drawings, does not include means to enable it to be deflated once inflation is complete - however the valve assembly 16 could be used with such further apparatus as to allow for subsequent deflation. When the packer and valve assembly 10 has been lowered to the desired depth typically a cementing plug or the like is pumped down the bore of the casing 23. As the cementing plug passes through the bore of the mandrel 12 it reaches the shear-off plugs 94 and the pumping force shears-off the plugs 94 thus revealing the inlet ports 38 and allowing inflation fluid to flow into the channel 72, through the ports 164 and into the channel 174 and thus into the lift cavity 118. In some cases the plugs 94 are manually removed from the packer and valve assembly 10 prior to its connection into the casing 23.

The inflation prevention valve 84 and the shear-off plugs 94 prevent inadvertent premature inflation of the inflatable packer 14 during lowering into the open hole 21 and prior to commencement of pumping of inflation fluid.

A pump at the drill rig is connected to the casing 23 and inflation fluid is pumped into the bore of the casing 23. Inflation fluid can be directed into the radial inlet ports 38 in a number of different ways, including using:

a landing collar to receive a cementing ball; a solid cement baffle collar or shoe to be drilled out later; a retrievable bridge plug; floating or cementing equipment to function as a temporary plug; or, a drillable plug or ball seat designed to shear at a predetermined pressure. These methods of directing inflation fluids into the inflatable packer 10 are well known in the field of cementing with inflatable packers.

The operation of any packer and valve assembly is conducted by people referred to as "operators". If the operator is inexperienced or inattentive there can be pressure spikes during the setup of the packer and valve assembly 10 in the open hole 21. Sometimes when the inflation fluid pump is first started it places a large pressure spike on the packer and valve assembly 10 which can lead to premature opening of ports in prior art packers. In the packer and valve assembly 10 of the present invention such pressure spikes are resisted by the shear-off plugs 94 and the pressure equalisation ports 124 and 198 thus avoiding inadvertent and / or premature inflation of the inflatable packer 14. Where a cementing plug is used, the inflation fluid cannot pass the plug in the bore of the casing 23 and so fills the casing 23 and is forced under pressure through the ports 38 and into the lift cavity 118. The pressure differential across the inflation preventer valve 84 produced by the pump increases and produces increased force at the end 180 of the lift cavity 118. When the force exceeds the shear strength of the pins 126b of the shear pins 126a the pins 126b shear off and the inflation preventer valve 84 is forced upwardly to the valve retaining sub 80 closing off the cavity 163 and ejecting any fluids therein out via the pressure equalisation port 124.

Further inflation fluid pumped into the casing 23 flows through the radial inlet ports 38, over the D-seals 29a, through the flutes 136 in the annular collar 138 of the upper valve sub 82, along the upper annular passageway 140, through the port 250, into the intermediate annular passageway 260, through the port 266, along the lower annular passageway 310, into the annular inlet 50 of the ferrule end 46 of the inflatable packer 14 and into an annular space between the elastomeric packer element 44 and the mandrel 12. The pressure of the inflation fluid builds up in the packer element 44 and causes it to expand until it reaches the bore of the open hole 21. The packer element 44 can then no longer expand ignificantly under increasing pressure of the inflation fluid.

Continued pumping of inflation fluid increases the pressure differential in the control valve 16 across the inflation shut-in valve 88 (from the cavity 140 to the shutting-in cavity 236, which increases an imbalance in upward and downward forces experienced by the inflation shut-in valve 88. This imbalance forces the inflation shut-in valve 88 downward towards the inflatable packer 14. This movement causes the saw tooth ridges 276 of the male annular ratchet component 272 to engage with the saw tooth ridges 290 of the female retaining ring 90. Increased pumping pressure forces the cavity 236 shut, expelling its contents out via the lower pressure equalisation port 198. The inflation shut-in valve 88 is thus in the locked condition and inflation fluid cannot leave the inflatable packer 14 and further increases in pumping pressure cannot reach the packer element 44 which is therefore safe from over- inflation and possible rupture. It is to be noted that the shut-in valve 88 may work effectively without the pressure equalisation port 198, provided the cavity 236 does not contain any incompressible liquid, paste or slurry from the assembly process.

It is also to be noted that when the valve 88 is fully shut-in the cavity 236 disappears as the radial shoulders defining the two longitudinal ends of the cavity meet and press against each other. At the same time the saw tooth ridges 276 engage with the ratchet component 272 to ensure positive locking of the valve 88 in the shut-in condition.

Once the shut-in valve 88 has moved to the closed condition the pump pressure can then be removed and the packer element 44 will remain inflated. Also, the operation of the collapse of the cavity 236 ensures that an operator of the tool detects a sharp increase in operating pressure indicating shut-in of the valve has been achieved and that de-pressurisation of the valve may commence.

It is known in the art of inflatable packers to assess the operation of control valves and inflatable packers by changes in pressure experienced by the pump used to pump fluid to inflate the packer 14.

In the case of use of cementitious inflation fluid pumping continues and the open hole annulus 20 filled with cement via a port collar, in known manner (such as in US Patent No 5,443,124 assigned to CTC International).

Upon completion and setting of said cement the bore plug and landing ring are drilled out and the well is ready for testing and other completion operations. ADVANTAGES

The packer and valve assembly 10 of the present invention has the advantage that it has relatively large annular flow passages internally of the control valve 16 so as to avoid blockage and erosion with packer inflation fluid such as cement. The use of sleeve valves provides a more reliable mode of change of state of the control valve 16 and is not prone to blockage or erosion as plagues prior art valves that rely upon narrow ports with sliding plugs operated against springs and shear pins, run in holes or bores.

Also, the one way locking mechanism ensures a positive engagement in the shut-in mode that can be detected by an operator and relied upon as proof of a definite lock.

Further, the collapse of the cavity 236 guarantees that the shut-in valve 88 reaches the limit of its travel into its shut-in mode of operation.

Still further, the packer and valve assembly 10 of the present invention has pressure equalisation ports 124, which together with the shear-off plugs 94 and the inflation preventer valve 84 avoid inadvertent inflation of the packer element 44 which may otherwise occur due to transient pressure spikes during the installation and setting up of the packer and valve assembly 10. The use of annular flow passages allows these equalisation ports 124 to be relatively large and so more effective than prior art equalisation ports.

MODIFICATIONS AND VARIATIONS

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. For example, a guide bush could be fixed to the outer curved surface of the mandrel 12 below the sliding end 46 of the inflatable packer 14, so as to avoid damage to the inflatable packer 14 during running in hole. Also, the plug or ball used to block the bore of the casing 23 during cementing could be used to break off the bodies 322 of the plugs 94 - in which case the plug would not be spherical in shape, but would have cylindrical sides capable of sharp engagement with the shear-off plugs 94. Further, other forms of locking means could be used to lock the inflation shut-in valve 88 into its closed condition, instead of the female ratchet ring 90 and male ratchet component 272. Still further, the sliding end ferrule 46 could be shear pinned to the mandrel 12 during running in and the pins sheared during inflation of the packer element 44.