The present invention relates to an apparatus and method for securing a tubular within another tubular or borehole, and creating a seal across an annulus in a well bore. In particular, though not exclusively, the invention relates to morphing dual sleeves on a tubular to form an isolation barrier which is resistive to collapse.

In the exploration and production of oil and gas wells, packers are typically used to isolate one section of a downhole annulus from another section of the downhole annulus. The annulus may be between tubular members, such as a liner, mandrel, production tubing and casing or between a tubular member, typically casing, and the wall of an open borehole. These packers are carried into the well on tubing and at the desired location, elastomeric seals are urged radially outwards or elastomeric bladders are inflated to cross the annulus and create a seal with the outer generally cylindrical structure i.e. another tubular member or the borehole wall. These elastomers have disadvantages, particularly when chemical injection techniques are used.

As a result, metal seals have been developed, where a tubular metal member is run in the well and at the desired location, an expander tool is run through the member. The expander tool typically has a forward cone with a body whose diameter is sized to the generally cylindrical structure so that the metal member is expanded to contact and seal against the cylindrical structure. These so-called expanded sleeves have an internal surface which, when expanded, is cylindrical and matches the profile of the expander tool. These sleeves work well in creating seals between tubular members but can have problems in sealing against the irregular surface of an open borehole. The present applicants have developed a technology where a metal sleeve is forced radially outwardly by the use of fluid pressure acting directly on the sleeve. Sufficient hydraulic fluid pressure is applied to move the sleeve outwards and cause the sleeve to morph itself onto the generally cylindrical structure. The sleeve undergoes plastic deformation and, if morphed to a cylindrical metal structure, the metal structure will undergo elastic deformation to expand by a small percentage as contact is made. When the pressure is released the metal structure returns to its original dimensions and will create a seal against the plastically deformed sleeve. During the morphing process, the inner surface of the sleeve will take up the shape of the surface of the wall of the cylindrical structure. This morphed isolation barrier is therefore ideally suited for creating a seal against an irregular borehole wall.

Such a morphed isolation barrier is disclosed in US 7,306,033, which is incorporated herein by reference. An application of the morphed isolation barrier for FRAC operations is disclosed in US2012/0125619, which is incorporated herein by reference. Typically, the sleeve is mounted around a supporting tubular body, being fixed at each end of the sleeve to create a chamber between the inner surface of the sleeve and the outer surface of the body. A port is arranged through the body so that fluid can be pumped into the chamber from the throughbore of the body.

In use, the pressure of fluid in the throughbore is increased sufficiently to enter the chamber and force the sleeve outwardly to morph to the generally cylindrical structure. Sufficient pressure has been applied when there is no return of fluid up the annulus which verifies that a seal has been achieved. Though the sleeve has been plastically deformed and will therefore hold its new shape, if a sufficient pressure differential is created across the sleeve wall, there is a possibility that fracture can occur and the seal may be lost. In one application, the pressure of fluid in the throughbore is maintained to keep a high pressure in the chamber. Indeed most sleeves are set by applying maximum pressure to the sleeve. Unfortunately, there is a risk that the pressure could be high enough to rupture the sleeve. Additionally, if the pressure differential acts in the opposite direction by a pressure drop in the throughbore or by an increase in fluid pressure in the annulus below the sleeve, the sleeve can be forced away from the cylindrical structure, causing loss of the seal.

To overcome this, a check valve is used in the port. This check valve is arranged to stop fluid returning to the throughbore. Application of sufficient fluid pressure will cause fluid to enter the chamber through the valve and the sleeve morphs to the cylindrical structure. When the seal is achieved, the pressure can be bled off to leave a trapped pressure within the chamber. This allows an isolation barrier to be created which does not need a constant fluid supply to maintain it in the sealed position.

A disadvantage of this system is in that it cannot compensate for pressure differentials across the sleeve. Pressure inside the sleeve will be fixed at a morph pressure and there will be a pressure within the wellbore annulus above and below the sleeve. This upper and lower annulus pressure may be different and if a sufficient pressure differential exists across the sleeve, the sleeve could collapse causing loss of the seal and the isolation barrier.

As described in US2012/0125619 for fracing, if a check valve is provided within the port, then at least one burst disk is also provided in a port formed all the way through the side wall of the sleeve or through the sidewall of the seal carrier, but is importantly only provided at the end of the sleeve that will be closest to the perforated section of the casing and therefore, will be closest to the end of the sleeve that will see the high pressure of the frac fluid when it is pumped . The burst disk will be arranged to burst and therefore let fluid within the chamber to flow into the annulus in the location of the formation to be frac'd in order to protect the rest of the sleeve, in situations where there is a pre-determined pressure differential across it. In other words, the burst disk can be intentionally sacrificed in order to protect the rest of the sleeve when a certain pressure differential is experienced-say 5,000 psi. Alternatively, and more importantly the burst disk can be intentionally burst to allow the high pressure fluid from the high pressure zone of the annulus into chamber to reinforce the sleeve. This arrangement will likely be used in situations where the isolation barrier must have a substantially higher performance in collapse. In operation, the sleeve will be inflated by for instance an expansion tool such that fluid is pumped through the check valve to inflate the sleeve. However, when the final morph fluid pressure is achieved (say 10,000 psi) the rupture disk is arranged to burst such that fluid can then communicate between the high pressure zone of the annulus and the chamber. After the disk has burst, this therefore means that there is zero differential pressure across the sleeve between the high pressure zone and the chamber and therefore allows the isolation barrier to be maintained as long as the rupture disk is on the high pressure side.

This arrangement has a number of disadvantages: in having to ensure that the isolation barrier is deployed in the correct orientation with the rupture disk arranged on the high pressure side; ensuring that pressure on the 'low' pressure side does not increase to be greater than that on the high pressure side; and only being able to morph a single sleeve at a time between the zones.

It is therefore an object of at least one embodiment of the present invention to provide a morphed isolation barrier which obviates or mitigates one or more disadvantages of the prior art. It is a further object of at least one embodiment of the present invention to provide a method of creating an isolation barrier in a well bore which obviates or mitigates one or more disadvantages of the prior art.

According to a first aspect of the present invention there is provided an isolation barrier, comprising :

a tubular body having a throughbore, the tubular body arranged to be run in and secured within a larger diameter generally cylindrical structure; a valve housing located on the exterior of the tubular body;

a first sleeve member positioned on the exterior of the tubular body with a first end being sealed thereto and a second end being sealed to the valve housing to create a first chamber within the first sleeve;

a second sleeve member positioned on the exterior of the tubular body with a first end being sealed thereto and a second end being sealed to the valve housing to create a second chamber within the second sleeve;

first and second rupturable barrier devices located at the first ends of the first and second sleeves, respectively; and

a valve arrangement located in the valve housing, the valve arrangement having a first position in which fluid flows from the throughbore to the first and second chambers and a second position which prevents the flow of fluid between the throughbore, the first chamber and the second chamber.

In this way, the sleeves can be morphed together and by rupturing the barriers, each side of the barrier is active to pressure and collapse is prevented regardless of the pressure differential across the barrier.

The large diameter structure may be an open hole borehole, a borehole lined with a casing or liner string which may be cemented in place downhole, or may be a pipeline within which another smaller diameter tubular section requires to be secured or centralised. The tubular body is preferably located coaxially within the first and second sleeves and is part of a tubular string used within a wellbore, run into an open or cased oil, gas or water well. Therefore the present invention allows a casing section or liner to be centralised within a borehole or another downhole underground pipe by provision of a morphable sleeve member positioned around the casing or liner. Centralisation occurs as the sleeve will expand radially outwardly at a uniform rate with the application of pressure through the port. Additionally, the present invention can be used to isolate one section of the downhole annulus from another section of the downhole annulus and thus can also be used to isolate one or more sections of downhole annulus from the production conduit.

Preferably the valve arrangement has three branches, the first branch being open to the throughbore, the second branch connecting to the first sleeve member and the third branch connecting to the second sleeve member. More preferably there is a one-way check valve in the second branch and a one-way valve in the third branch. In this way, pressurised fluid in the throughbore can enter the first and second sleeves simultaneously but is prevented from travelling back to the throughbore or between the chambers.

Preferable the ruptureable barrier devices are rupture disks, such as burst disk devices or the like. Preferably the ruptureable barrier devices are set to rupture at pressures around the morphed pressure value so that the sleeves are morphed prior to rupture of the barrier devices.

Optionally, the first branch of the valve arrangement may include a ruptureable barrier device. In this way, fluids can be pumped down the tubing string into the well without fluids entering the sleeves until it is desirous to morph the sleeves. According to a second aspect of the present invention there is provided a method of setting an isolation barrier in a well bore, comprising the steps:

(a) locating first and second sleeve members side-by-side on the exterior of a tubular body and sealing them thereto to create first and second chambers therebetween;

(b) running the tubular body on a tubular member into a wellbore and positioning the sleeve members at a desired location within a larger diameter structure;

(c) pumping fluid through the tubular member and increasing the fluid pressure to provide fluid at a morphed pressure value at the sleeve members;

(d) simultaneously pumping fluid at the morphed pressure value into the chambers causing the sleeves to move radially outwardly and morph against an inner surface of the larger diameter structure;

(f) once morphed, preventing fluid from passing between the tubular member and the chambers, and between the chambers; and

(g) creating an opening at a first end of the first sleeve member and at a second end of the second sleeve member.

In this way, once the morph is complete, fluid can enter each sleeve from the annulus above and below the barrier. Each sleeve thus supports the other sleeve and prevents collapse of the barrier.

The large diameter structure may be an open hole borehole, a borehole lined with a casing or liner string which may be cemented in place downhole, or may be a pipeline within which another smaller diameter tubular section requires to be secured or centralised.

Preferably, step (d) includes the step of pumping fluid through a valve arrangement between the sleeves. The step may also include pumping fluid through two one way check valves, each arranged at an input to each sleeve, respectively.

Preferably, the method includes the step of rupturing a disc at the valve arrangement to allow fluid to enter the chambers when the pressure reaches a desired value. This allows pumping of fluids into the well without fluid entering the sleeve members.

The method may include the steps of running in a hydraulic fluid delivery tool, creating a temporary seal above and below the valve arrangement and injecting fluid from the tool into the chambers via the valve arrangement.

In the description that follows, the drawings are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.

Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein including (without limitations) components of the apparatus are understood to include plural forms thereof.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which :

Figure 1 is a cross-sectional view through an isolation barrier according to an embodiment of the present invention; and

Figure 2 is a cross sectional view through the isolation barrier of Figure 1, following morphing.

Reference is initially made to Figure 1 of the drawings which illustrates an isolation barrier, generally indicated by reference numeral 10, including a tubular body 12, sleeve members 14a, b with chambers 16a, b and a valve arrangement 20, located between the sleeve members 14a, b according to an embodiment of the present invention.

Tubular body 12 is a cylindrical tubular section having at a lower end (not shown), a box section and at an upper end (not shown), a pin section for connecting the body 12 into a tubing string such as casing, liner or production tubing that is intended to be permanently set or completed in a well bore. Body 12 includes a throughbore 30 which is co-linear with the throughbore of the string.

Tubular body 12 is located coaxially within the sleeve members 14a, b which are arranged side by side along the tubular body 12. Sleeve members 14a, b are each a steel cylinder being formed from typically 316L or Alloy 28 grade steel but could be any other suitable grade of steel or any other metal material or any other suitable material which undergoes elastic and plastic deformation. The sleeve members 14a, b are appreciably thin-walled of lower gauge than the tubing body 12 and are preferably formed from a softer and/or more ductile material than that used for the tool body 12. The sleeve members 14a, b may be provided with a non-uniform outer surface 40a, b such as ribbed, grooved or other keyed surface in order to increase the effectiveness of the seal created by the sleeve members 14a, b when secured within another casing section or borehole.

An elastomer or other deformable material may bonded to the outer surface 40a, b of the sleeves 14a, b; this may be as a single coating but is preferably a multiple of bands with gaps therebetween. The bands or coating may have a profile or profiles machined into them. In this way, the elastomer bands are spaced such that when the sleeves 14a, b are being morphed the bands will contact the inside surface 82 of the open borehole 80 first. The sleeve members 14a, b will continue to expand outwards into the spaces between the bands, thereby causing a corrugated effect on the sleeve members 14a, b. These corrugations provide a great advantage in that they increase the stiffness of the sleeve members 14a, b and increase their resistance to collapse forces.

The sleeves 14a, b are arranged oppositely so that a first end 42a, b of each sleeve 14, b is at the centre of the barrier 10. The first ends 42a, b are attached to a stop 44 machined in the outer surface 36 of the body 12. Attachment is via pressure-tight welded connections to provide a seal. An O-ring seal (not shown) may also be provided between the inner surfaces 46a, b of the sleeves 14a, b and the outer surface 36 of the body 12 to act as a secondary seal or backup to the seal provided by the welded connection at the stop 44. Attachment could also be by means of a mechanical clamp. Stop 44 is an annular ring formed around the circumference of the outer surface 36 of the body 12. Second stops 48a, b are arranged at second ends 50a, b of the sleeves 14a, b. The second stops 48a, b may be clamped to the body 12 so that the sleeves 14a, b can be slid onto the body 12 over the ends during assembly. A seal 52a, b is provided at the outer surface 36 of the body 12 forward of the stop 48a, b so that the seal 52a, b is between the sleeve 14a, b and the body 12. This provides a sliding o-ring seal so that the second end 50a, b of each sleeve 14a, b is permitted to move towards the first stop 44 relative to the body 12. Thus when the sleeve members 14a, b are caused to move in the radially outward direction, this causes simultaneous movement of the sliding seals 52a, b towards each other, which has the advantage in that the thickness of the sleeves 14a, b is not further thinned by the radially outwards expansion.

Stop 44 together with the inner surface 46a, b of each sleeve 14a, b and the outer surface 36 of the body 12, define chambers 16a, b, one in each sleeve 14a, b. While in Figure 1, the chambers 16a, b have a distinct volume, this can be made near negligible by arranging the sleeves 14a, b and body 12 close together. However, following morphing the chamber 16a, b will have a volume within the void created between the body 12 and the sleeves 14a, b.

Located in a portion of the stop 44 is a valve housing 22. Valve housing 22 has three branches 24, 26a, b which meet at a junction 18 in the housing 22. A first branch 24 provides a path, from a port 32 on the inner surface 38 of the body 12 through the side wall 34 of the body 12, to provide a fluid passageway between the throughbore 30 and the junction 18. A second branch 26a provides a path from the junction 18 to the outer surface 36 of the body 12 within the first chamber 16a. Similarly, a third branch 26b provides a path from the junction 18 to the outer surface 36 of the body 12 within the second chamber 16b. Thus a path exists between the throughbore 30 at the port 32 to both of the chambers 16a, b.

Branches 24, 26a, b form a valve arrangement 20. One way check valves 28a, b are located in the branches 26a, b so that fluid can only pass in a direction from the throughbore 30 into the chambers 16a, b. Fluid is prevented from escaping into the tubular body 12 or the other chamber 16b, a. Thus the chambers 16a, b can be filled simultaneously from fluid in the throughbore 30. The check valves 28a, b also close when the pressure within the chambers 16a, b reaches a predetermined level, this being defined as the morphed pressure value. Also arranged at the port 32 is a rupture disc 56. The rupture disc 56 is rated to a pressure below, but close to the morphed pressure value. In this way, the rupture disc 56 can be used to control when the setting of the sleeves 14a, b is to begin. The disc 56 can be operated by increasing pressure in the throughbore 30 towards the morphed pressure value, but will prevent fluid exiting the throughbore 30 into the chambers 16a, b until this pressure value occurs.

At each end 50a, b of each sleeve 14a, b there is provided a rupturable barrier device in the form of a burst disk 54a, b. For ease of construction the burst disks 54a, b are shown mounted in the end portions of the sleeves 14a, b, sometimes referred to as seal carriers, but they may be located through the thinner portions if desired. Mounting through the end portions ensures that they are not morphed outwards and prevented from operating. Each disk, when burst, provides a direct passageway for fluid to pass between each chamber 16a, b and the annulus 42 between the outer surface 36 of the tubular body 12 and the wall 82 of the borehole 80.

Reference will now be made to Figure 2 of the drawings which provides an illustration of the isolation barrier once set and is used to describe a method for setting an isolation barrier within a well bore according to an embodiment of the present invention. Like parts to those in the earlier Figures have been given the same reference numerals to aid clarity.

In use, the barrier 10 is conveyed into the borehole by any suitable means, such as incorporating the barrier 10 into a casing or liner string (not shown) and running the string into a wellbore 78 until it reaches the location within the open borehole 80 at which operation of the barrier 10 is intended. This location is normally within the borehole at a position where the sleeves 14a, b are to be expanded in order to, for example, isolate the section of borehole 80a located above the sleeves 14a, b from that below 80b in order to provide an isolation barrier between the zones 80a, 80b. It will be appreciated that a further barrier can be run on the same string 76 so that zonal isolation can be performed across a zone in order that an injection, frac'ing or stimulation operation can be performed on the isolated formation located between the two barriers.

Each sleeve 14, a, b can be set by increasing the pump pressure in the throughbore 30 to a predetermined value which represents a pressure of fluid at the port 32 being the morphed pressure value. The morphed pressure value will be calculated from knowledge of the diameter of the body 12, the approximate diameter of the borehole 80 at each sleeve 14a, b, the length of each sleeve 14a, b and the material and thickness of the sleeve 14a, b. The morphed pressure value is the pressure sufficient to cause the sleeve 14a, b to move radially away from the body 12 by elastic expansion, contact the surface 82 of the borehole and morph to the surface 82 by plastic deformation.

When the morphed pressure value is applied at the port 32, the rupture disc 56 will have burst as it is set below the morphed pressure value. Fluid will enter the first branch 24 and reach junction 18 whereupon it will divide and enter the second 26a and third 26b branches simultaneously. The check valves 28a, b are arranged to allow fluid from the throughbore 30 to enter each of the chambers 16a, b. This fluid will increase pressure in each chamber 16a, b so as to cause each sleeve 14a, b to simultaneously move radially away from the body 12 by elastic expansion, contact the surface 82 of the borehole and morph to the surface 82 by plastic deformation. When the morphing has been achieved, the check valves 28a, b will close and trap fluid at a pressure equal to the morphed pressure value within the chambers 16a, b. The check valves 28a, b prevent fluid from escaping from either chamber 16a, b back to the throughbore or to the other chamber 16b, a.

The sleeves 14a, b will each have taken up a fixed shape under plastic deformation with an inner surface 46a, b matching the profile of the surface 82 of the borehole 80, and an outer surface 86a, b also matching the profile of the surface 82 to provide a seal which effectively isolates the annulus 84a of the borehole 80 above the barrier 10 from the annulus 86 below the sleeve 14.

When morphed pressure is reached in the sleeves 14a, b the burst disks 54a, b are set to rupture. This may be at 10,000psi, say. This opens a fluid passageway between the lower annulus 84a and the chamber 16b, and between the upper annulus 84b and the chamber 16a. Thus each chamber 16a, b becomes active to the fluid pressure on that side of the barrier 10. In this way, a pressure differential is prevented from being established between the annulus and the chamber on either end of the barrier 10. Collapse of either sleeve 14a, b is therefore prevented.

If two barriers 10 are set together then zonal isolation can be achieved for the annulus 84 between the barriers. At the same time the sleeves 14a, b have effectively centered, secured and anchored the tubing string 76 to the borehole 80. An alternative method of achieving morphing of the sleeve 14a, b is shown in Figure 1. This method uses a hydraulic fluid delivery tool 88. Once the string 76 reaches its intended location, tool 88 can be run into the string 76 from surface by means of a coiled tubing 90 or other suitable method. The tool 88 is provided with upper and lower seal means 92a, b, which are operable to radially expand to seal against the inner surface 94 of the body 12 at a pair of spaced apart locations in order to isolate an internal portion of body 12 located between the seals 92a, b; it should be noted that said isolated portion includes the fluid port 32. Tool 88 is also provided with an aperture 96 in fluid communication with the interior of the string 76.

To operate the tool 88, seal means 92 are actuated from the surface to isolate the portion of the tool body 12. Fluid, which is preferably hydraulic fluid, is then pumped under pressure, which is set to the morphed pressure value, through the coiled tubing such that the pressurised fluid flows through tool aperture 96 and then via port 32 through the valve arrangement 20 and into chambers 16a, b and acts in the same manner as described hereinbefore.

A detailed description of the operation of such a hydraulic fluid delivery tool 88 is described in GB2398312 in relation to the packer tool 112 shown in Figure 27 with suitable modifications thereto, where the seal means 92a, b could be provided by suitably modified seal assemblies 214, 215 of GB2398312, the disclosure of which is incorporated herein by reference. The entire disclosure of GB2398312 is incorporated herein by reference.

Using either pumping method, the increase in pressure of fluid directly against the sleeves 14a, b causes the sleeves 14a, b to move radially outwardly and seal against a portion of the inner circumference of the borehole 80. The pressure within the chambers 16a, b continues to increase such that the sleeves 14a, b initially experience elastic expansion followed by plastic deformation. The sleeves 14a, b expand radially outwardly beyond their yield point, undergoing plastic deformation until the sleeves 14a, b morph against the surface 82 of the borehole 80 as shown in Figure 2. If desired, the pressurised fluid within the chamber 16a, b can be bled off following plastic deformation of the sleeves 14a, b. Accordingly, the sleeves 14a, b have been plastically deformed and morphed by fluid pressure without any mechanical expansion means being required .

When the morphing has been achieved, the check valves 28a, b will close and trap fluid at a pressure equal to the morphed pressure value within the chambers 16a, b. At the same time, the burst disks 54a, b will rupture allowing annulus fluid to enter each chamber 16a, b or morph fluid to escape into the annulus until there is zero pressure differential at the first ends 50a, b of each sleeve 14a, b. Any change in the pressure within the chambers 16a, b or in the annulus 84a, b is transmitted between between the two to maintain a zero differential pressure.

The principle advantage of the present invention is that it provides an morphed isolation barrier in a well bore which is resistive to collapse.

A further advantage of the present invention is that it provides a method for setting a morphed isolation barrier in a well bore which allows multiple barriers to be set simultaneously in the well bore.

A yet further advantage of the present invention is that it provides an isolation barrier in a well bore in which pressure within a morphed sleeve is matched to that of the neighboring annulus so that the thickness of the sleeve can be reduced to improve the sealing contact during morphing. It will be apparent to those skilled in the art that modifications may be made to the invention herein described without departing from the scope thereof. For example, while a morphed pressure value is described this may be a pressure range rather than a single value to compensate for variations in the pressure applied at the sleeves in extended well bores. Each sleeve 14a, b may be independently morphed. There may be a fluid exclusion means located between the sleevesl4a,b to prevent hydraulic lock at the centre during morphing .