The present invention relates to an improved apparatus and method for delivering fluid at a high pressure to a predetermined location in a downhole environment and in particular, though not exclusively, to inflate a packer in a wellbore.

Packers are well known in the exploration and production of oil and gas wells and used to form a seal 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. The seal prevents fluid flow in the annulus and can therefore be used to isolate portions of the annulus and allow access to distinct sections of the formation. Packers may also anchor an inner tubular to an outer tubular or borehole wall. One type of packer is the inflatable packer. In an inflatable packer, a bladder, skin or sleeve is inflated by fluid pressure to expand an outer wall of the bladder, skin or sleeve into contact with the borehole wall or another tubular, such as casing, located in the wellbore. Early inflatable packers were formed from a rubber bladder with elastomeric seals being developed later. These materials can degrade particularly in the presence of chemicals injected in the wellbore. Metals are now being used which can expand under hydraulic fluid pressure to morph against the borehole wall or other casing. An example of a packer using this technology is described in WO2016/055775.

There are a number of requirements to achieve successful inflation of a packer downhole. Firstly, inflation must not occur until the packer has reached its location and ^setting' of the packer is needed. Most packers are set when a predetermined pressure is reached in the wellbore and thus the packer must not inflate before this pressure is reached. Secondly, ample fluid pressure must be applied to the inner surface of the outer wall to cause radial expansion sufficient for the outer wall to contact a wellbore wall such as the borehole wall or outer tubular and create a seal. Obviously the fluid pressure needs to be greater than the pressure in the well annulus for expansion to occur, and for eiastomeric packers only a small differential of a few thousand psi would be needed, however to morph metal downhole requires greater setting pressures typically in excess of ten thousand psi. Finally, the setting pressure needs to be maintained in the inflated packer so that the seal is not breached. The need to deliver fluid at high pressures to a deep location in a well poses difficulties. When pumping from surface it is known that fluid pressure decreases with depth which makes calculating pressure at depth inadequate to ensure an accurate setting pressure is reached or the pump pressure at surface needed to ensure setting pressure is reached at depth is beyond the capability of available pumps used at surface. Additionally, for many well designs, it is undesirable to pump high pressure fluid through the tubing string .

Hydraulic fluid delivery tools have been developed which can be run into a string from surface by means of coiled tubing or other suitable method. US 7,017,670 presents such a tool, but this still relies on high pressure fluid being pumped from surface with many of the same disadvantages as described above. To create high fluid pressure in the wellbore, pressure intensifiers are used . WO2016/051169 describes a pressure intensifier for morphing tubulars downhole. An elongate mandrel defines an inner bore, being co- axially located within an elongate hollow outer cylindrical body to form a co-axial annular bore therebetween. Pistons are mounted upon the mandrel with each piston having an annular fluid facing face extending across the annular bore, with fluid communication between the inner bore and the annular bore to act upon each face. Stops are located on an inner surface of the outer cylindrical body to limit travel of each piston. A morph fluid is located in the annular bore between an opposing face of a first piston and a first stop, with the first stop having delivery ports to deliver the morph fluid at a greater pressure than the pressure of fluid delivered through the inner bore. The morph fluid is effectively held in an enclosure and when an operating fluid pressure is applied through the bore, the pistons are released to operate in series, multiplying the pressure applied to the enclosure and consequently to the fluid in the enclosure. The morph fluid can be used to inflate a packer. However, a disadvantage of this arrangement is that the enclosure must be made large enough to hold a sufficient volume of fluid to inflate the packer and achieve the setting pressure in the packer when inflated.

It is an object of an embodiment of the present invention to provide a method of delivering fluid at an increased pressure to a chamber located in a wellbore which mitigates at least some of the disadvantages of the prior art.

It is a further object of an embodiment of the present invention to provide apparatus for delivering fluid at an increased pressure to a chamber located in a wellbore which does not require pumping of fluid at the increased pressure from surface.

According to a first aspect of the present invention there is provided a method of delivering fluid an increased pressure to a chamber located in a wellbore, the method comprising the steps:

(a) locating a tool including a chamber in a wellbore, the chamber being at a first chamber pressure and first chamber volume;

(b) opening the chamber and introducing fluid at a first operating pressure to the chamber;

(c) closing the chamber, the chamber then being at a second chamber pressure and a second chamber volume; (d) activating a pressure intensifier; and

(e) opening the chamber and introducing fluid from the pressure intensifier into the chamber, the chamber then being at a third chamber pressure and a third chamber volume.

By staging the pressure increases in the chamber, the fluid introduced by the pressure intensifier adds to the pressure in the chamber to provide a cumulative pressure and volume increase within the chamber. Preferably, the step of closing the chamber is achieved via a valve. The valve may be a sliding sleeve valve. Alternatively the valve may be a check valve. In this way, the pressure cannot drop within the chamber so that a cumulative pressure increase occurs. Preferably, the third chamber pressure is greater than the second chamber pressure which is greater than the first chamber pressure. This ensures a cumulative pressure increase.

Preferably, the third chamber volume is greater than the second chamber volume which is greater than the first chamber volume. A cumulative increase in volume provides a method for inflating a packer in a wellbore, where the first chamber volume represents an uninflated packer, the second chamber volume represents a partially inflated packer and the third chamber volume represents an inflated or set packer. In this way, the pressure and volume in the final enclosure of the pressure intensifier does not require to be sufficient to fully inflate the packer but merely to top it up as the packer is already partially inflated when the pressure intensifier is activated. In an alternative embodiment, the second and third chamber volumes are the same. This may occur in a metal sleeved packer were inflation is achieved using the fluid introduced at step (b) and the second chamber pressure is sufficient to elastically deform the outer metal sleeve of the packer. The fluid introduced by the pressure intensifier is then used to plastically deform the outer metal sleeve so that it retains its shape in the inflated position.

Optionally, the first, second and third chamber volumes may be constant. In this way, the greatest cumulative pressure can be delivered to the chamber. This fluid pressure may actuate a tool in the wellbore. The first operating pressure may be casing pressure present in the wellbore. Alternatively, the first operating pressure may be a pump pressure delivering fluid from surface.

Preferably the method includes the step of closing the chamber when the third chamber pressure and third chamber volume is reached. In this way, the high pressure is isolated and for a packer, deflation is prevented. Thus the setting pressure can be maintained in an inflated packer so that the seal is not breached . According to a second aspect of the present invention there is provided apparatus for delivering fluid at an increased pressure to a chamber located in a wellbore, being a downhole arrangement comprising :

a first fill mechanism including valve means to control fluid flow into the chamber;

a second fill mechanism including a pressure intensifier and an output, the output arranged to match an input of the chamber;

wherein the first fill mechanism is actuated by fluid flow at a first operating pressure through the downhole arrangement to allow fluid flow into the chamber and the second fill mechanism is actuated at a second operating pressure, wherein the second operating pressure is greater than the first operating pressure. In this way, a cumulative fluid pressure can be achieved in the chamber via the first fill mechanism and then by the pressure intensifier.

Preferably the downhole arrangement comprises a tubular body providing a throughbore. The tubular body has an outer surface and an inner surface. In this way fluid can be pumped down the throughbore to operate the fill mechanisms.

Preferably the chamber is formed between the outer surface of the tubular body and a morphable sleeve arranged around the tubular body. Fastening means may be present at longitudinal ends of the chamber to hold the morphable sleeve to the tubular body. In this way, the downhole arrangement provides a packer with integral pressure intensifier. Preferably the valve means is a check valve. In this way the first fill mechanism is a simple valve which lets valve fluid into the chamber but does not let the fluid exit the chamber. More preferably the valve means includes a rupture disc set to rupture at the first operating pressure. In this way the first stage fill of the chamber can only begin at the first operating pressure. This prevents any inflation of the packer occurring before a desired pressure is reached in the throughbore.

In an embodiment, the valve means comprises at least one fluid passageway through the tubular body and a sliding seal arrangement at an outer surface, the sliding seal having a sealing surface to provide a seal on the outer surface and prevent fluid flow from the throughbore to the chamber and wherein the sliding seal arrangement is operated by the fluid flow via a first fluid passageway through the tubular body. Preferably, the sealing surface is co-linear with a central, longitudinal axis of the tubular body. Preferably, there are first and second fluid passageways through the body. Preferably, the first fluid passageway is a conduit through the body between a first port at an inner surface of the tubular body and a second port at the outer surface of the tubular body. Preferably the second fluid passageway is a conduit through the body between a third port at an outer surface of the tubular body and a fourth port at the outer surface of the tubular body, the third and fourth ports being spaced apart longitudinally on the outer surface of the body. In this way, the throughbore can be kept clear of obstructions only requiring a first port at the outer surface of the throughbore.

There may be a plurality of first fluid passageways. There may be a plurality of second fluid passageways. Preferably the plurality of fluid passageways are equidistantly arranged circumferentially around the longitudinal axis. In this way, the conduits may be narrow in diameter to ease machining thereof but a sufficient volume of fluid flow can be achieved through the body to fill the chamber.

Preferably, a housing is located on the outer surface wherein the second port exits into the housing and the sealing surface is arranged in the housing. The housing may be a sleeve around the body and the sliding seal may be a sliding sleeve. Alternatively the housing may be local to the second port with the sliding seal being a piston arranged in the housing. In this way, the sliding seal is contained so that fluid may act upon it.

Preferably, the third port exits from the housing and fluid exiting the fourth port is used to fill the chamber. The fourth port may exit directly into the chamber. Alternatively, there may be a third fluid passageway from the fourth port to the chamber. In this way, the fill mechanism can be spaced longitudinally apart from the chamber. By separating the housing and the chamber the downhole arrangement can be thin walled to aid deployment into a well bore. Advantageously, the sliding seal is arranged in the housing in a first configuration wherein fluid can flow from the second port to the third port to fill the chamber and a second configuration wherein the sealing surface seals a port to prevent fluid flow to the chamber. Preferably, in the second configuration the sealing surface seals the third port. In this way, a fixed fluid pressure can be retained in the chamber.

More preferably, the sliding seal moves between the first configuration and the second configuration by the action of fluid pressure against an end surface of the sliding seal. Thus the sealing arrangement can be actuated by fluid flow through the first passageway from the throughbore.

Preferably, the fill mechanism includes retaining means to hold the sliding seal in the first configuration. The retaining means may be a shear pin. In this way, the sliding seal can close the passageway to the chamber at a preselected fluid pressure.

Preferably, the fill mechanism includes locking means to keep the sliding seal in the second configuration. The locking means may be a locking ring on the sliding seal which engages in a recess in the housing. In this way, the chamber is sealed at a preselected fluid pressure for the life of the well. Advantageously, the housing is formed between the outer surface of the tubular body and an inner surface of a sleeve arranged around the tubular body. An end of the sleeve may abut or include the chamber. In this way, the assembly is simple to construct. Preferably the second fill mechanism is formed from the tubular body and the pressure intensifier comprises: an elongate mandrel defining the throughbore bore into which fluid is delivered, the mandrel being co-axially located within an elongate hollow outer cylindrical body;

at least one annular piston extending inwardly from the cylindrical body across the annular bore to the mandrel and shaped such that a discreet fluid receiving void is created between an active surface of the piston and the elongate mandrel;

at least one input port to enable fluid communication between the inner bore and the fluid receiving void;

at least one stop located on an outer surface of the mandrel to limit travel of each piston;

trapped fluid located in an enclosure of the annular bore between an opposing surface of a first piston and a first stop;

wherein at least one delivery port exits the enclosure to deliver the trapped fluid at a greater pressure than the pressure of fluid delivered through the inner bore.

In this way, a fluid pumped under pressure down the inner bore will create a force used to move the at least one piston which in turn causes delivery of the trapped fluid at increased pressure to the chamber.

Preferably, there is a plurality of pistons arranged along the cylindrical body. In this way, as the total force is the sum of force from all the pistons, the pressure of the trapped fluid can be increased without increasing the pressure of fluid pumped downhole. Additionally, this arrangement allows the trapped fluid to be injected into the chamber on a single stroke.

Preferably the plurality of pistons and the outer cylindrical body are secured together and form a pressure development mechanism which can move relative to the mandrel. By retaining the mandrel in a fixed position and moving the pressure development mechanism, the efficiency of the pressure intensifier is increased by minimisation of the development of leak paths causing pressure loss. In addition, provision of the moving parts mounted in an annular arrangement around a fixed mandrel means that the tool is easier to assemble i.e. it can be constructed in a 'top down' configuration.

Preferably, the delivery ports exiting the enclosure form delivery conduits having an inner diameter less than the inner diameter of the annular bore between each adjacent piston and stop. Having delivery conduits of a narrower bore than that of the annular bore causes a further increase in pressure in the trapped fluid delivered along the delivery conduits.

Preferably, the intensifier includes a locking mechanism, the locking mechanism being arranged to hold the pressure development mechanism in a first position until actuation of the pressure intensifier is required. In this way, the first fill mechanism can operate before the second fill mechanism. Advantageously, the locking mechanism is releasable at a predetermined fluid pressure applied through the mandrel. More preferably, the predetermined fluid pressure for release can be adjustable. In this way, the fluid pressure for release can be set in the field when other operable fluid pressures in the well will be known.

Preferably, the locking mechanism is at least one shear pin which secures the pressure development mechanism in a predetermined position at an entry end of the pressure intensifier. Use of a shear pin locking mechanism enables the pressure development mechanism only to be actuated simply by provision of sufficient hydraulic pressure when actuation is required. Advantageously, the locking mechanism is accessible from an outer surface of the tool. In this way, the pressure to shear the pin and activate the tool, can be selected at any time dependent upon the pressure required to activate other tools being used in the well. 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 schematic view through an apparatus including a first and a second fill mechanism according to an embodiment of the present invention; Figures 2(a) and 2(b) are cross-sectional views through a first fill mechanism first and second configurations, respectively, for the apparatus of Figure 1 according to an embodiment of the present invention;

Figures 3(a) and 3(b) are cross-sectional views through a second fill mechanism first and second configurations, respectively, for the apparatus of Figure 1 according to an embodiment of the present invention; and

Figures 4(a), 4(b) and 4(c) are cross-sectional views through wellbores illustrating the method of the present invention on an (a) uninflated packer, (b) mainly set packer and (c) fully set packer according to an embodiment of the present invention.

Reference is initially made to Figure 1 of the drawings which illustrates a downhole apparatus, generally indicated by reference numeral 10, having a first fill mechanism 12 and a second fill mechanism 14 to deliver fluid at an increased pressure to a chamber 16 in a tool 18 within a wellbore 20 according to an embodiment of the present invention.

Downhole apparatus 10 presents a substantially tubular body 22 with a throughbore 24 arranged on a central axis 26. Throughbore 24 is of sufficient diameter to allow other tools and strings through the apparatus 10. The throughbore 24 also provides access for pumping fluids through the downhole apparatus 10. Downhole apparatus 10 forms part of tool 18 in the preferred embodiment, however apparatus 10 may be a separate tool or sub connected to a further tool including the chamber 16.

The first fill mechanism 12 provides a controlled passageway for fluid to travel into the chamber 16. The fluid will typically be from the throughbore 24 having been pumped from surface or it may be arranged to take fluid from the annulus 28 between the body 22 and the wellbore wall 30. Fluid may also be supplied to the first fill mechanism 12 via a conduit (not shown) in the tool string running to surface or by a hydraulic fluid delivery tool as described in the prior art. The first fill mechanism is actuated to open a port and let fluid enter the chamber 16. Actuation can be by any suitable downhole actuation mechanism known to one skilled in the art. For example it may be by a rupture disc set at a pressure to match the fluid pressure needed to enter the chamber 16. When sufficient fluid has entered the chamber 16 through the first fill mechanism 12, the mechanism 12 will close preventing fluid exiting the chamber and maintaining a second chamber pressure and second chamber volume in the chamber 16. The second chamber pressure and second chamber volume will typically be greater than the initial or first chamber pressure and first chamber volume. Any suitable downhole closure mechanism can be used as would be known by those skilled in the art. For example, a simple check valve set at the desired second chamber pressure can be used. In the preferred embodiment the first fill mechanism 12 is as illustrated in Figures 2(a) and 2(b). Fill mechanism 12 is provided through the tubular body 22, to fill the chamber 16 with fluid from the throughbore 24 of the tubular body 22, as shown in Figure 1. Body 22 has an inner surface 25 which forms the wall of the throughbore 24 and is co-linear with the throughbore of the string. Body 22 also has an outer surface 27 profiled to provide a number of functions.

Between the inner 25 and outer 27 surfaces of the body 22 is arranged a first fluid passageway 31. First fluid passageway 31 extends from a first port 32 on the inner surface 25 to a second port 34 on the outer surface 27. A second fluid passageway 36 is also arranged through the body 22 to provide a conduit between a third port 38 on the outer surface 27 and a fourth port 40, also arranged on the outer surface 27. To achieve the second fluid passageway 36 travelling between two points, ports 38,40 on the outer surface 27, two conduits 42,44 are drilled into the body 22 from each port 38,40 respectively. The conduits are angled to meet at a point 46 in the body 22 where the direction of the second fluid passageway 36 turns. The second 34, third 38 and fourth 40 ports are spaced longitudinally along the outer surface 27 from an upper end 23 to a lower end 21.

Towards the upper end 23 there is a stop 48 being a ring located around the body 22 and attached thereto. At the upper end 50 of the stop 48, the face 52 is sloped while the opposing face has two abutting surfaces 54,56. These surfaces 54,56 are perpendicular to the longitudinal, central axis of the throughbore 24. Abutting the first surface 54 is lower end 58 of an outer sleeve 60. Outer sleeve 60 is arranged around the body 22, extending over the ports 34,38,40 to the chamber 16. In an embodiment, the outer sleeve 60 includes a fastening 62 to hold a morphable sleeve 64 of a packer to the body 22 with the chamber 16 being located between the morphable sleeve 64 and an outer surface 29 of the outer sleeve 60.

The outer sleeve 60 has a profiled inner surface 66. On the surface 66 is an upwardly facing abutting surface 68 arranged between the third 38 and fourth 40 ports. This abutting surface 68 of the outer sleeve 60 together with the downwardly facing abutting surface 56 of the stop 48, the outer surface 26 of the body 22 and the inner surface 66 of the outer sleeve 60 define a housing 70. The second 34 and third 38 ports access the housing 70. Located in the housing 70 is a piston 72. In the embodiment of Figure 2(a), the piston 72 is a sleeve located around the body 14. Piston 72 has a length which is shorter than the distance between the abutting surfaces 56,68 of the housing 70, so that the piston 72 can move longitudinally with respect to the body 14. A shear pin 74, provides retaining means to initially hold the piston 72 in a position wherein its lower end face 76 abuts the surface 68. The shear pin 74 is located between the piston 72 and the outer sleeve 60. This arrangement of the piston 72 at the lower end of the housing 70 and retained by the shear pin 74, is referred to as the first configuration.

The lower end 78 of the piston 72 is narrower than an upper end 80 and the housing 70 is sized at its lower end 82, to provide a sliding fit to the piston 72. The lower end 82 of the housing 70 extends from the downward side of the second port 34 to the abutting surface 68. A seal 84 is arranged between the inner surface 86 of the piston 72 and the outer surface 27 of the body 22. A seal 88 is also arranged between the outer surface 90 of the piston 72 and the inner surface 66 of the outer sleeve 60. Seals 84,88 are located so as to isolate the lower 78 and upper 80 ends of the piston 72 in the housing 70.

The piston 72 has two apertures 92,94 through the lower end 78. The apertures 92,94 are spaced apart longitudinally and substantially align with the second 34 and third 38 ports when the assembly 10 is in the first configuration. At the second port 34, a recess 96 is provided in the body 22 so that fluid can flow from the passageway 30 into the aperture 92 when the aperture 92 is located over the recess 96. As the outer surface 90 of the piston 72 runs against the inner surface 66 of the outer sleeve 60, a channel 98 is provided longitudinally in the outer surface 90 of the piston 72. Channel 98 provides a flow path connecting the first aperture 92 with the second aperture 94 and extending to the lower end face 78 of the piston 72.

Seals 81,83 are arranged on the outer surface 26 of the body 14 at either side of the third port 38. Each seal 81,83 is positioned circumferentially around the body 22 to prevent the flow of fluid between the inner surface 86 of the piston 72 and the outer surface 26 of the body 22 along the lower end 82 of the housing 70.

At the upper end 80 of the piston 72 there is arranged a snap-ring 85 located in a recess on the inner surface 86. A recess 87 is provided on the outer surface 26 of body 14 at the upper end 108 of the housing 70 into which the snap-ring 85 can locate when the piston 72 moves to the lower end 89 of the housing 70. Recess 87 has a depth such that the snap-ring 85 will locate partially therein to lock the piston 72 to the body 22.

At the fourth port 40, the inner surface 66 of the outer sleeve 60 and the outer surface 27 of the body 22 are profiled to provide a fluid flow passageway 91 from the fourth port 40 to the chamber 16. The passageway 91 separates the fill mechanism 12 from the chamber 16 by longitudinally spacing the fill mechanism 12 from the chamber 16.

While a single flow path between the throughbore 24 and the chamber 16 has been described, it will be appreciated that any number of flow paths may be incorporated in the mechanism 12. Multiple ports 32 could be arranged circumferentially through the body 22, with a sleeve or multiple individual pistons 72 arranged at the exit port 34. Any number of channels 98 could be arranged around the sleeve with an end gully provided to connect them all around the outer surface 90 of the piston 72. Equally, multiple passageways 36 could be provided and a series of parallel arranged channels 91 on the outer surface 26 of the body 14 could direct fluid through multiple ports into the chamber 16.

In use, the first fill mechanism 12 is arranged on a string as shown in Figure 1. The mechanism 12 is in the first configuration, shown in Figure 2(a). Piston 72 is arranged as a sleeve over the tool body 22 and located against the lower face 68 of the housing 70. Stop 48 is positioned on and fixed to the body 22. Outer sleeve 60 is then placed over the body 22 to form the housing 70 of the fill mechanism 12. Alignment of the shear screw 74 will align the ports 34,38 with the apertures 92,94.

The mechanism 12 is then run-in the well in the first configuration. A rupture disk may be located at the first port 32 to prevent any flow of fluid into the mechanism 12 until desired. When the chamber 16 requires to be filled, fluid pressure at the first port 32 is increased. This increase in fluid pressure may be by increased pumping through the string or may be by running a setting tool to the location of the port 32 and delivering pressurised fluid to the port 32 via the tool.

Fluid flow into port 32 from the throughbore 24 will pass through passageway 30, exit at port 34 into recess 96 and enter aperture 92 in the piston 72. From the aperture 92 fluid will flow down the channel 98 to enter the third port 38 via aperture 94. Piston 72 is held in place by shear pin 74 so the piston 72 will not move. The presence of seals 84 and 88 ensures the fluid is therefore directed to the fourth port 40, through the second fluid passageway 36. At the fourth port 40 there is an uninterrupted flow path through the passageway 110 into the chamber 16. The chamber 16 will therefore be filled with pressurised fluid from the throughbore 24. The chamber 16 will continue to fill until the pressure in the chamber 16 matches the shear rating on the shear pin 74. At this point, fluid acting on the between the seals 84,88 will be sufficient to shear the pin 74 and the piston 72 will move upwards in the housing 70.

Passageway 93 is shown in Figure 2(b) of the drawings. Passageway 93 joins the second port 34 to the aperture 92 and will increase in size as the piston 72 is moved in the housing 70. This flow of fluid through the aperture 92 will travel through channel 98 and fill a lower housing chamber created by the separation of surfaces 76 and 68. As chamber 16 fills, pressure on surface 76 will continue to move the piston 72 through the housing 70 towards the upper end 22. During movement the seals 84,88 on the piston remain sealed to the surfaces 27,66 of the outer sleeve 60 and body 14, respectively, to keep fluid within the lower end 82 of the housing 70.

As piston 72 moves upwards aperture 94 will move away from port 38 and the inner surface 86 of the piston 72 will slide over the port 38. Aperture 94 will pass over the seal 100 and consequently the passageway 36 is blocked, being sealed at the port 38 by the piston 72 acting as a sliding sleeve valve in the longitudinal direction, co-linear with the central axis. Debris is kept from the port 38 by the action of the sealing surface 78 being drawn across the seals 81,83. The sliding sleeve, piston 72, is contained within a housing 70 located between the inner surface 24 of the body 22 and the outer surface 97 of the outer sleeve 60. Sealing the port 38 contains fluid at a fixed pressure within the chamber 16.

To hold the piston 72 in the sealed position, the piston 72 is moved until the snap-ring 85 is free to move inwardly into the recess 87 on the body 14. Snap-ring 85 bridges between the body 14 and the piston 72 to prevent relative longitudinal movement therebetween. A stop 99 is also present in the housing to limit upward movement of the piston 72. In this position, as illustrated in Figure 2(b), the mechanism 12 is considered as locked, being in a second configuration.

The seal at port 38 can be maintained for the life of the well fluid exiting the chamber 16 and maintain the pressure within the chamber 16. The first fill mechanism 12 is as described in WO2015/022552 which is incorporated herein by reference.

Returning to Figure 1, it can be seen that the chamber 16 is also accessed via a further port 11. Port 11 connects to a delivery conduit 152 from the second fill mechanism 14 located towards the end 23 of the tool 18. A check valve 13 is located on the conduit 152 to prevent fluid travelling from the chamber 16 to the second fill mechanism 14. The second fill mechanism 14 comprises a pressure intensifier.

In the preferred embodiment the second fill mechanism 14 is as illustrated in Figures 3(a) and 3(b). The pressure intensifier comprises an outer cylindrical body 112 and an inner tubular body 22 in the form of a mandrel 122. The mandrel 122 is the tubular body 22 of the first fill mechanism 12. The outer cylindrical body 112 is provided with a first end 114, a second end 116 with a central length 117 therebetween formed by an outer cylindrical wall 118.

Cylindrical body 112 is of metal construction and is a substantially hollow tubular having a cylindrical wall 118 with an inner surface 119 defining a bore 120 therethrough. Within bore 120 is arranged co-axially a cylindrical mandrel 122, also of metal construction, having an outer surface 123 and an inner surface 124 that defines an inner bore 126. The mandrel 122 forms the tubular body 22 and is further provided with a first end 130 having a suitable fitting as are known in the art for connecting the mechanism 14 into a string not shown for running the downhole apparatus 10 into a wellbore. Suitable strings may be coiled, tubing, drill pipe, liner and the like. The mandrel 122 is thus fixed on a string. The second end 132 forms the tubular body 22 of the first fill mechanism 12. The inner bore 126 aligns with and forms the throughbore 24 of the downhole apparatus 10.

Arranged within bore 120 at first end 114 of the cylindrical body 112 is a locking mechanism 134 which in this case comprises shear pins that extend through openings 133 in the cylindrical wall 118 and are received in recesses 135 formed in the first end 130 of mandrel 122. The shear pins 134 secure the cylindrical body 118 and mandrel 122 relative to one another. The shear pins can be removable inserted into the recesses 135 through openings 133 such that the pins 134 used can be provided at different strengths so that a suitable pin is used depending on the environment in which the apparatus 10 is deployed and the level of fluid pressure which will pass through the bore 126 in general operation as well as the level of fluid pressure required to actuate the pressure intensifier 14.

A pressure development mechanism 137, which may be considered as a low pressure housing, is formed from the first end 114 along the central length 117 of the cylindrical body 112 with pistons 140 provided at intervals along the central length 117. A pressure application mechanism 136 is formed at the second end 132 of the mandrel 122. The pressure application mechanism 136 may be considered as a high pressure housing.

In the pressure development mechanism 137, the central mandrel 122 continues co-axially through cylindrical body 112. The cylindrical body 112 is provided along its central portion 117 with actuating pistons 140. In the embodiment show, the mechanism 137 is provided with two actuating pistons 140a, b and a high pressure piston 140c with each piston 140a, b, c associated with a segment of mandrel 122a - c respectively. The pistons 140a, b, c are spaced apart along, and project perpendicularly inwards from the cylindrical wall 118. Each piston 140a, b, c is substantially annular and extends across bore 120 such that a movable seal is formed between internal piston surface 142 and recessed portion 125 of outer surface 123 of mandrel 122.

The pressure development mechanism 137 further includes annular stop mechanisms 144 which are spaced equidistantly apart and project from the outer surface 123 of mandrel 122. In the embodiment shown, two annular stop mechanisms 144a, b are provided projecting from the from the outer surface 123 of mandrel portions 122a and 122b respectively such that a movable seal is formed between inner surface 119 of the cylindrical body 112 and the projected surfaces 145a, 145b of the mandrel stops 144a, 144b. The third annular stop mechanism 144c is formed by the active surface 145c of the pressure application mechanism 136.

The mandrel 122 is further provided with ports 146 spaced apart along the length of the mandrel. In this case, three ports 146a, 146b and 146c are provided. The ports 146a, b,c enable fluid communication between the mandrel bore 126 and voids 148a, 148b, 148c defined between an active surface 149 of pistons 140, a void defining surface 150 and recess surface 125 of outer surface 123 of the mandrel 122. Between the leading face 143a, b, c of the pistons 140a, b, c, stop mechanisms 144a, b, c, recessed outer surface 125 of mandrel 122 and inner surface 119 of cylindrical body 122, there are further defined annular voids 120a, 120b, 120c. Each of annular voids 120a, 120b is provided with a port 127 which extends through wall 118 of body 112.

In the pressure application mechanism 136 the mandrel 122 is provided with a segment 122d having a cylindrical wall 121d that overlaps cylindrical wall 121c of segment 122c in a manner which causes it to extend annularly across bore section 120c such that a movable seal is formed between surface 123d and 119d. The thickness of the mandrel wall 123 where segments 122c and 122d overlap provides additional resilience to pressure created by the pressure intensifier. A delivery conduit 152 is defined longitudinally through cylindrical wall 121d of pressure application mechanism 136 such that it is parallel to bore 126. A delivery port 154 allows fluid communication between void 120c and delivery conduit 152. The delivery conduit 152 is operable then to provide fluid communication between annular void 120c and a desired the chamber 16. The diameter of the fluid delivery conduit 152 is less than the diameter or annular void 120c which, in turn, is less than the diameter of annular voids 120a and 120b. The annular void 120c is provided with application fluid 156, which may be any suitable fluid including, for example, clean water.

The second fill mechanism 14 is operable to have two states. In the first state, the components of the second fill mechanism 14 are arranged in a first position as is shown in the embodiment illustrated in Figure 1. The second fill mechanism 14 is in a first state prior to actuation of the mechanism 136 to apply fluid under pressure to the chamber 16.

In the first state, the first end 114 of the body 112 is arranged such that it extends longitudinally away from first end 130 of mandrel 122 and is secured in position by retaining mechanism 134. End 130 is attached to a sting providing a continuous central bore 126 through the pressure intensifier of the second fill mechanism 14. The pressure application mechanism 136 extends longitudinally beyond the second end 16 of cylindrical body 112.

The inner surface 119, outer surface 124, actuating piston 140a and mandrel void defining surface 150a co-operate in the first state so as to form a chamber 148a. The first actuating piston 140a is arranged so that it is spaced remotely along the bore 120 from stop 144a. The actuating piston 140a, inner surface 119, outer surface 125 and stop 144a co ^¬ operate in the first state to form a chamber 120a.

Similarly, the actuating piston 140b is arranged spaced remotely along the bore 120 from stop 144b. The actuating piston 140b, void defining surface 150b, outer surface 125 and stop 144a co-operate in the first state to form an enclosure 148b. The actuating piston 140b, inner surface 119, outer surface 125 and stop 144b co-operate in the first state to form an enclosure 120b.

High pressure piston 140c is arranged mounted projecting inwardly from cylinder 112 such that in a first state it is closely adjacent to stop 144b and defines enclosure 148c. The high pressure piston 140c, outer surface 125, void defining surface 150c and fluid facing face 154 of bore stop 144c co-operate in the first state to form a sealed enclosure 120c which is filled with operating fluid 156.

Each co-operating mandrel and cylindrical body or piston surface is provided with a resilient seal ring 160 such as a rubber or elastomeric o- ring or similar, that provides a resilient seal between the adjacent surfaces. The seal rings 160 allow lateral movement between the mandrel surfaces and the inner wall and piston surfaces whilst preventing the passage of fluid therebetween.

Each piston 140 may be integrally formed with mandrel 122 or is attached to the cylindrical body segments by a screw mechanism such that the pistons 140 act as joining mechanisms between adjacent cylindrical body segments. This enables the cylindrical body and piston arrangement to be constructed, and built up from the bottom of, a mandrel secured in position. Upon actuation, the moveable components of intensifier, namely, the components of the cylindrical body 112 and piston arrangement, through the process of receiving and applying fluid under pressure, move to a second state. The arrangement of the components in the second state is shown in Figure 3(b).

In use, the second fill mechanism is connected on a string at end 130 and the first fill mechanism 12 with the chamber 16 is connected at end 136 of the mandrel 122. As both the first and the second fill mechanisms 12,14 are actuated by fluid pressure through the throughbore 24, a determination is made as to the maximum fluid pressure which is likely to be applied through the string when the apparatus 10 is in the wellbore and activation is not required. This is the pressure rating set for the rupture disc of the first fill mechanism 12. The shear pins 134 are then selected to shear at a greater pressure than the maximum fluid pressure calculated to actuate the first fill mechanism 12. The shear pins 134 can then be arranged in the locking mechanism. The selection of the shear pin rating can be done in the field.

The apparatus 10 is then run in the wellbore whereupon fluid in the bore 126 enters ports 146 to fill the enclosures 148. Additional fluid outside the string will fill the enclosures 120. The second fill mechanism 14 will not activate and no components will move until the pressure of fluid entering the ports 146 is sufficient to shear the pins 134. The hydraulic fluid pressure entering the ports 146 acts on the active surface 150 of the pistons 140 and when this is greater than the shear pressure on the pins 134, these will shear releasing the cylindrical body 112 and piston arrangement 140. Consequently the voids 148 will increase in size as the pistons 140 move longitudinally downwards over the mandrel 122.

As the pistons 140 move downwards, enclosures 120 will reduce in size as the volume of each void decreases. Fluid in the enclosures 120 will be forced out of the mechanism 14 through ports 127. Enclosure 120c does not include a port 127 and instead, the exit of fluid is through the delivery conduit 152. The fluid is the operating fluid sealed in the enclosure 120c before activation. High pressure piston 144c thus acts upon the application fluid 156 and forces the fluid 156 into the delivery conduit 152, passing through the check valve 13 and adding to the fluid under pressure in the chamber 16. In Figure 3(b), the arrangement of the components of the second fill mechanism 14 are shown in a second state, subsequent to activation according to an embodiment of the invention. In this embodiment, outer cylindrical body 112 has been driven forward as has pistons 140a, b such that they now abut against stops 144a, b respectively and high pressure piston 144c has been driven forward to abut against wall end stop 154. The force created by hydraulic pressure acting upon pistons 140a, c cumulatively acts upon application piston 144c such that the fluid 156 is driven through delivery conduit 152 with a much greater force than that in the throughbore 24.

The cumulative pressure against pistons 140a, b creates a total force applied to the operating fluid 156 by the movement of piston 144c which is the sum of force from all the pistons 140a, be. The increased thickness of overlapped walls 122c, 122d, 118c enables the force of pressure applied through to the conduit 152 to be directed to the chamber without damaging or causing deformation of the second fill mechanism 14.

The number of pressure development segments used in the pressure intensifier can be varied depending upon the level of pressure required for a particular use of the intensifier; the more pressure development segments in the form of pistons 140, outer cylindrical segments 112 and stops 148 included in the intensifier, the more pressure will can be applied from the second fill mechanism 14. Fewer segments and pistons will result in a lower pressure being applied by the second fill mechanism 14.

The second fill mechanism 14 is a pressure intensifier. While one embodiment of a pressure intensifier has been described, it will be appreciated by those skilled in the art that other pressure intensifiers exist which could be used, for example, the pressure intensifier described in WO2016/051169 which is incorporated herein by reference. Additionally, pressure intensifiers which contain motors which may be electrically driven can also be used.

Returning to Figure 1, it can be seen that the first fill mechanism 12 is arranged at the chamber 16. In this embodiment, the tool 18 is a packer and a morphable sleeve 64 is fastened to the body 22 with the chamber 16 being located between the morphable sleeve 64 and the outer surface 29 of the outer sleeve 60. The morphable sleeve 64 is located around a portion of the tubular body 22 with the body 22 located coaxially within the morphable sleeve 64. Morphable sleeve 64 is 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 morphable sleeve 64 is appreciably thin-walled of lower gauge than the tubing body 22 and is preferably formed from a softer and/or more ductile material than that used for the tool body 22. The morphable sleeve 64 may be provided with a non-uniform outer surface such as ribbed, grooved or other keyed surface in order to increase the effectiveness of the annular seal created by the morphable sleeve 64 when secured within another casing section or borehole.

An elastomer or other deformable material may be bonded to the outer surface of the morphable sleeve 64; this may be as a single coating but is preferably a multiple of bands with gaps therebetween.

Thus the tool 18 can be considered as a packer with integral fill and intensifier features 10.

In use, tool 18 is constructed with the sleeve 64 against the outer surface 29 of the tubular body 22 providing a chamber 16 therebetween which will have an initial or first chamber pressure and a first chamber volume. The packer will be uninflated . The rupture disc of the first fill mechanism 12 is set at a value at which it is desired for the packer 18 to start inflating in the wellbore 20. Shear pin 74 is set to a value at which the packer 18 will be partially set and will typically reflect a pressure value which is easily achievable by pumping fluid from surface. In the second fill mechanism 14, the shear pins 134 are set at a higher pressure rating than shear pin 74. Shear pins 134 can advantageously be set in the field so that adjustment can be made depending on the pressure of fluids which may have to be pumped down the throughbore 24. The packer 18 is then run to a desired location in the wellbore 20. As long as pressure in the throughbore 24 is kept below the disc rupture pressure, the packer 18 will remain uninflated. This is shown in Figure 4(a).

When the packer requires to be inflated or set, fluid pumped through the throughbore 24 would be increased to a low pressure value sufficient to rupture the disc in the first fluid mechanism 12. As described hereinbefore, this will fill the chamber 16. If, for example, we pressure up to a low pressure, say 4,000psi, this will start the setting process on the packer 18. Fluid introduced to the chamber 16 will increase the pressure in the chamber 16 until it is sufficient to elastically expand the packer sleeve 64 and thus move it radially outwards across the annulus 28 and contact the wellbore wall 30. Once the packer 18 is mainly set with the 4,000psi, we pressure up to 4,500psi which will shear pins 74 in the first fill mechanism 12 and the piston 72 will close and lock the 4,000psi in the packer 18. Consequently the chamber 16 is now at a second chamber pressure, 4,000psi, and a second chamber volume, representing the mainly set packer 18. Thus the second chamber pressure and volume is less than the first chamber pressure and volume. This is shown in Figure 4(b). Then we pressure 5,000psi, which is the rating of the shear pins 134 of the second fill mechanism 14. This will activate the pressure intensifier as described herein before, the mandrel 122 will stroke down with the piston 144 pushing the application fluid 156 past the check valve 13 and into the chamber 16. Application fluid 156 at a multiple of the 5,000psi pressure is delivered to the chamber 16. The volume of application fluid 156 is relatively small e.g. less than one litre, so the mainly set packer 18 is fully set by the great increase in pressure in the chamber 16. Typically, this pressure increase will be sufficient to plastically deform the packer sleeve 64 so it permanently sets against the wall of the wellbore 20 or another tubular in which the packer 18 is located. The check valve 13 holds this new pressure inside the packer 18. The chamber 16 will now be at a third chamber pressure and volume, with the volume being only slightly greater than or equal to the second chamber volume, while the pressure is significantly greater than the second chamber pressure, say 10,000psi depending on the number and surface area of pistons in the second fill mechanism 14. This allows you to set the packer 18 with 5,000psi but get effectively 10,000psi into the packer 18. Those skilled in the art will appreciate that these pressures could be adjusted based on what is needed for the well, it could be 3,000psi with a 3x multiple or whatever is required. This is shown in Figure 4(c). In particular, as the volume of application fluid 156 can be kept small the second fill mechanism can be kept appreciable small. Thus by providing a two stage fill process, the packer can be inflated to a high pressure without requiring a large void of fluid to be stored downhole.

The embodiment described refers to a packer, but it will be appreciated by those skilled in the art that any chamber can be filled to a high pressure downhole using the apparatus and method of the present invention. For example, the chamber may be a void at a piston face and the piston is actuated by the delivery of high pressure fluid. The principle advantage of the present invention is that it provides a method and apparatus for delivering fluid at a first pressure and then at an increased pressure to a chamber located in a wellbore which does not require pumping of fluid at the increased pressure from surface.

The further advantage of the present invention is that it provides a method and apparatus for delivering fluid to a chamber located in a wellbore where the delivery is staged and the fluid pressure is cumulatively increased at each stage.

A further advantage of at least one embodiment of the present invention is that is that it provides a method and apparatus for delivering fluid at a first pressure to mainly set and then at an increased pressure to fully set an inflatable packer located in a wellbore which does not require a fluid reservoir at the increased pressure to entirely inflate the packer to be stored in the apparatus.

It will be appreciated by those skilled in the art that modifications may be made to the invention herein described without departing from the scope thereof. For example, in the second fill mechanism the ports are shown in the above embodiments as small round holes through the mandrel. However, the instead of a single hole, each port may comprise a plurality of holes, or the port may be shaped as a slit, a slot or a plurality of slots formed around the circumference of the mandrel. The pistons and stops may also have different shapes and configurations. Additionally, the fill mechanisms may be arranged at one or both sides of the chamber. The fill mechanisms may be arranged to fill more than one chamber.