DOWNHOLE SEALING TOOL ASSEMBLY AND ASSOCIATED METHODS

Description

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 63/570,954 filed on Mar. 28, 2024, and entitled, “Downhole Sealing Tool Assembly and Associated Methods”, and which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

Aspects of the present disclosure relate to downhole sealing tools, such as oil well packers, as well as methods for assembling, setting, using and retrieving such tools. Other aspects relate to the various associated tools used in combination with the downhole sealing tools.

BACKGROUND

An oil well packer may be defined as a mechanical device for blocking the passage of fluids and or debris in an annular space. Most of this debris emanates from the production zone perforations in a well, can be as large as gravel, but mostly silt and sand coming from the oil-bearing formation.

Downhole packers are well known in the oil and gas industry for sealing an annulus between various weight casings and mandrels at different underground locations in an oil well, for example, to exploit different production zones. Conventional downhole packers include multi-element elastomeric packers, packers including a single elastomeric element having metal or mesh back-ups, and inflatable packers.

Inflatable packers utilize air or other fluid injected into an expandable element to expand the outer shell to reach the interior of the casing. In inflatable packers, the inflation pressure must be higher than the system pressure in order to maintain a positive seal.

SUMMARY

In accordance with the present disclosure, there is provided a Downhole Sealing Tool comprising:

• • a tubular section forming an enclosed channel, the tubular section comprising a cylindrical mounting surface extending at least partially along the length of the channel;
  • a set of multiple rings mounted on the cylindrical mounting surface, wherein the set of multiple rings comprise alternating deflection and deformable rings,
  • wherein each deflection ring has angled sides such that the deflection ring is wider towards the cylindrical mounting surface,
  • wherein each deformable ring has angled sides complementary to the angled sides of the deflection rings such that the deformable ring is wider away from the cylindrical mounting surface; and
  • wherein, in response to the multiple rings being axially compressed from a non-compressed configuration to a compressed configuration, each expandable ring is pushed away from the cylindrical mounting surface by the complementary angled sides.

The cylindrical mounting surface may extend at least partially along the length of the channel from one end.

At least one of the deformable rings and/or deflection rings may be formed from metal. (e.g., J55 or equivalent, K55 or equivalent, L80/4140, brass, copper, aluminium, or any malleable steel). The deformable rings and/or deflection rings may be formed from elastomer.

The Downhole Sealing Tool may comprise multiple deformable rings, wherein the multiple deformable rings comprise at least one elastically deformable ring and at least one plastically deformable ring.

A said cylindrical mounting surface may face outwards away from the channel. A said cylindrical mounting surface may face inwards towards the channel.

The cylindrical mounting surface may be recessed from an outer diameter of the tubular section (e.g., have a smaller inner diameter than the tubular section).

The cylindrical mounting surface may be recessed from an inner diameter of the tubular section (e.g., have a greater inner diameter than the tubular section).

In a non-compressed configuration, the outer surface of the set of multiple rings may be aligned with a surface of the tubular section. This may help the tool pass through the casing while being positioned.

One or more of the deformable rings may be a cut ring. One or more of the deformable rings may be a continuous ring. A ring may be circularly symmetric.

The Downhole Sealing Tool may be a liner hanger. The outer seal may connect to a casing (e.g., a production casing), and the inner seal may connect to a liner.

The inner seal may be activated prior to positioning downhole. The outer seal may be activated after having been positioned downhole.

The Downhole Sealing Tool may comprise only one seal (e.g., an inner seal or an outer seal).

The Downhole Sealing Tool may comprise a ratchet ring housing having an inner core and an outer core connected by a ratchet ring, which allows the inner core to be moved axially in only one permitted direction with respect to the outer core, and wherein one of the cores is aligned with the set of multiple rings, and the other core is connected to the tubular housing such that, when the ratchet ring is activated in the permitted direction, the multiple rings are compressed. This ratchet ring means that when the seal is activated using pressure, when the pressure is released, the seal remains in an axially compressed configuration. It will be appreciated that a ratchet ring may also be used to activate an inner seal. In such embodiments, the inner core may engage with the set of multiple rings, while the outer core is aligned with the tubular housing.

The Downhole Sealing Tool may comprise a tubular sub section which has a threaded connected for connecting to the tubular section, such that when the threaded connection between the tubular section and the sub section is tightened, the multiple rings are axially compressed.

The Downhole Sealing Tool may comprise a spring bed positioned between the threaded connection and the multiple rings.

According to a further aspect, there is provided a method of activating a Downhole Sealing Tool as described herein, the method comprising: axially compressed the multiple rings from a non-compressed configuration to a compressed configuration, thereby pushing each expandable ring away from the cylindrical mounting surface.

According to a further aspect, there is provided an Entry Guide Assembly comprising:

• • a pipe section;
  • an entry guide section connected to one end of the pipe section, wherein the entry guide section and connected pipe section form a continuous closed channel,
  • wherein the entry guide section has a larger outer diameter than the pipe section, and
  • wherein entry guide comprises an inner flared surface at an end away from the pipe section; and
  • wherein the entry guide comprises axial access channels positioned between the outer diameter of the pipe, and the outer diameter of the entry guide, the access channels being configured to allow push rods to pass through the entry guide to control mechanisms mounted on the pipe.

The access channels may comprise axial elongate channels.

The access channels may comprise slots.

The entry guide may comprise torque lugs, the torque lugs comprising a circularly asymmetric section which can be engaged by a running tool such that the rotation of the Entry Guide about the tubular axis can be controlled.

The entry guide may comprise an annular recess configured to engage with a running tool so that the axial position of the running tool with respect to the Entry Guide is fixed.

The pipe section and the entry guide section may be connected using a threaded connection.

According to a further aspect, there is provided a setting assembly comprising:

• • the entry guide assembly as described herein;
  • a compression activated seal mounted on the outside of the pipe section; and
  • a running tool comprising multiple push rods configured to pass through the enter guide section such that the seal can be controlled by moving the push rods through the access channels.

According to a further aspect, there is provided a Running Assembly comprising:

• • a central tubular sliding sleeve guide with a central channel and a stop positioned on the outside of the sliding sleeve guide,
  • a sliding sleeve mounted around the sliding sleeve guide, wherein the sliding sleeve is configured to be axially moved between a first position at a first end of the sliding sleeve guide and a second position at a second end of the sliding sleeve guide; and
  • a finger collet mounted around the sliding sleeve guide, wherein the finger collet comprises multiple axially aligned deformable fingers arranged around the circumference of a ring, each finger comprising a smooth inner surface which extends along the finger's entire length and an outwardly projecting protuberance on the outer surface at an end distal from the ring,
  • wherein, when the sliding sleeve is in the first position, the sliding sleeve is positioned radially between the sliding sleeve guide and the figure collet, thereby preventing inward deformation of the fingers, and, when the sliding sleeve is in the second position, inward deformation of the fingers is permitted.

The sliding sleeve may be temporarily held in the first position using shear pins.

The running assembly may comprise a sliding sleeve hydraulic chamber at one end of the sliding sleeve, wherein when the sliding sleeve hydraulic chamber is pressurized, a force is exerted on the sliding sleeve along the sliding sleeve guide from the first position to the section position.

The sliding sleeve guide may comprise a closure mechanism for blocking the central channel, thereby allowing the central channel upstream from the closure mechanism to be pressurized.

The closing mechanism may be a ball drop.

The running assembly may comprise multiple axially oriented push rods.

The running assembly may comprise one or more push rod hydraulic chambers for activating the push rods.

The running assembly may comprise torque lugs, the torque lugs comprising a circularly asymmetric section which can be engaged by an entry guide such that the rotation of the entry guide about the tubular axis can be controlled.

According to a further aspect, there is provided a Pawl Grip assembly comprising:

• • a first tubular section having a pawl insert mounted to the inner diameter of the tubular section using a shear ring, and having an inclined surface;
  • a second tubular section, being axially connectable to the first tubular section,
  • a pawl ring positioned between the first and second tubular sections on the inclined surface of the pawl insert, the pawl ring being configured such that, when the second tubular section is axially moved towards the first tubular section, the pawl ring engages with the inclined surface of the pawl insert which pushes the pawl ring inwardly,
  • and wherein, in response to the pawl ring moving away from the second tubular section with sufficient force, the shear ring is sheared which allows the pawl insert to move and the pawl to expand outwardly.

The first tubular assembly may comprise an interior recess for receiving the sheared pawl insert and expanded pawl.

The pawl may comprise serrated inwardly facing gripping surfaces.

The pawl insert may have an annular shape.

The pawl ring may have a gap to allow the pawl ring to bend inwardly as the pawl ring engages with the inclined surface of the pawl insert. The pawl ring may be a split ring.

The deformable rings may be continuous or have a cut (e.g., be a piston, or split ring). The cut may be a skive cut, a butt cut, a step cut, or any other ring cut type.

Using multiple deformable rings within a single seal may help keep the Downhole Packer Tool aligned with the component (e.g., casing and/or liner) to which the Downhole Packer Tool is sealing.

The closing mechanism may comprise a flap valve.

The delivery assembly may comprise three sub-assemblies: a Sacrificial Housing sub-assembly, a Downhole Sealing Tool sub-assembly, and a Running Tool sub-assembly.

After the Downhole Sealing Tool sub-assembly is set downhole, only the Running Tool sub-assembly may be returned to surface. The Running Tool sub-assembly may comprise a drop Ball Seat and Ball, which is also returned to the surface. The Running Tool sub-assembly may be used repeatedly for setting multiple Downhole Sealing Tools.

The Downhole Sealing Tool may be deployed using drill pipe or a service rig work string. The Downhole Sealing Tool may be deployed on production tubing (e.g., 5½ inch).

The Delivery System may be activated by surface hydraulic means following a Ball drop procedure.

The Sacrificial Housing Sub-assembly may be able to carry up to 3000 m or more of liner (e.g., 7.0 inch, 23.0 lb/ft) suspended below.

The Delivery Assembly may be configured to fit within a pipe having a diameter between 4-12 inches. The Delivery Assembly may have a length between 40-80 inches. The Downhole Sealing tool may have a length of between 10-25 inches. Each ring may have a width of between 0.5-2 inches. The downhole tool may be capable of sealing to outwardly to a diameter of between 6 and 10 inches. The down hole tool may be cable of sealing to inwardly to a diameter of between 4 and 8 inches. The Downhole Sealing Tool may have a size of 9⅝″×7″, 11¾″×9⅝″ or 7″×4½″, where the first number in each pair represents the inner diameter which the outer seal is sealing against (e.g., the outer casing), and the second smaller number in each pair represents the outer diameter which the inner seal is sealing against (e.g., the liner).

The Sacrificial Housing Assembly may comprise torque lugs. The torque lugs may be used to control axial rotation or twisting of the assembly.

The finger collet may help lock the Running Tool Sub-assembly in place to the entry guide of the Sacrificial Housing sub-assembly.

Shear pins may be used to lock out radial finger collet displacement. A shear sleeve may be used to lock out finger motion.

The shear sleeve shear pins may be arranged in a single or in multiple (e.g., two) rows. Each row may comprise multiple (e.g., 4-10) shear pins.

Activation may be initiated by a ball drop from surface. It will be appreciated that the ball may be pumped to the seat in horizontal applications.

The sliding sleeve may be activated using hydraulic pressure prior to activating the push rods.

Hydraulic chambers of the push rods may be fed with inlet ports equidistantly spaced in the pressure head to deliver fluid directly from the production tubing.

Hydraulic activation volume may be confined between soft seats. The total stroke length of the push rods may be greater than 2 inches. The total stroke length of the push rods may be less than 5 inches.

The operational order of setting the Downhole Sealing Tool may be as follows:

• • 1) Position Downhole Sealing Tool within the wellbore,
  • 2) Ball drop from surface and/or pump into place, if necessary,
  • 3) Build internal pressure-piston activation of the pushrods axially compresses and sets the outer seal of the Downhole Sealing Tool,
  • 4) Continue to increase production string tubing annulus pressure to force the shear sleeve down to shear the shear pins (thereby releasing the collet and disengaging the Running Tool Sub-Assembly from the Sacrificial Housing Sub-Assembly),
  • 5) Pick up weight on production string tubing and return to surface.

The Downhole Sealing Tool may comprise one or more of: a ratchet ring and a pawl brake system.

The internal seal may be dynamically activated by a Spring Bed. The internal seal may be activated by screwing a threaded connection.

The pawl brake system may be actuated at assembly (e.g., at surface); The pawl brake system may serve to hold the Downhole Sealing Tool in place on the Liner during hydraulic piston activation to activate the outer seal.

At peak pressure activation prior to shear sleeve release, a shear ring of the pawl system may release which allows the Downhole Sealing Tool to move slightly down.

The pawl system components can move into an internal recess (e.g., within the bottom sub), thus releasing the grip of the pawl on the liner, allowing floatation of the liner within the internal seal.

The Sacrificial Housing sub-assembly may comprise two parts: an entry guide and a pup joint or piece of piping. The pup joint may be at least 3 ft long.

Multiple torque lugs may be positioned on the inside of the entry guide. The entry guide may comprise one or more recesses for receiving the collet.

The entry guide may comprise multiple through-holes (e.g., slots) spaced (e.g., equally) around the circumference. There may be between 4 and 12 (e.g., 8) access channels. The access channels may be in the form of a dovetail slot.

The Push Rods may be considered to reach around or reach through the Entry Guide to provide longitudinal axial compression to the outer seal.

The Downhole Sealing Tool sub-assembly sits below the Entry Guide. The Downhole Sealing Tool sub-assembly sits above the threaded connection for connecting the liner.

The shear ring of the pawl braking system may be broken in response to thermal expansion of the liner after the Downhole Sealing Tool has been set. The shear plane (engineered weak point/shear point) may be broken in response to thermal expansion of the liner after the Downhole Sealing Tool has been set. A shear plane may also be referred to as a designed point of failure.

API grade K55 may have the same Chemical composition as grade J55, they both has the same yield, but its minimum tensile strength is about 26% higher compared to J55. J55 has a Yield strength of 379-552 MPa (55-80 ksi), and a Minimum tensile strength of 517 MPa (75 ksi). K55 has a Yield strength of 379-552 MPa (55-80 ksi), and a Minimum tensile strength of 665 MPa (95 ksi).

API 5CT (10th Edition) defines delivery conditions for steel casing and tubing pipes used for oil wells installation, it covers pup joints, coupling stock, coupling material, and accessory materials, and establishes requirements for three product specification levels (PSL-1, PSL-2, and PSL-3). The requirements for PSL-1 are the basis of this standard.

In the context of this disclosure, up and down, top and bottom, above and below are defined with respect to the well and the surface. The top is at or towards the surface of the well and objects are considered to be moving up when moving towards the surface. Likewise, the bottom is at or towards the furthest extent of the well away from the surface, and objections are considered to be moving down when moving towards the bottom.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Detailed Description section below, one or more embodiments of the present technology are described in relation to the attached figures. These embodiments are intended to provide a better understanding of the invention, how the invention may be put into practice, and to demonstrate some of the advantages of the invention. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention. Similar reference numerals indicate similar components.

FIG. 1 is a side cut-through view of an embodiment of a Downhole Sealing Tool.

FIG. 2a is a side cut-through view of an embodiment of a Sacrificial Housing Sub-Assembly.

FIG. 2b is a side transverse cross-section view of an embodiment of the Sacrificial Housing Sub-Assembly.

FIG. 2c is a perspective view of an embodiment of a Sacrificial Housing Sub-Assembly.

FIG. 3 is a perspective view of one side of a further embodiment of a Sacrificial Housing Sub-Assembly connected to the Downhole Sealing Tool of FIG. 1.

FIG. 4a is an enlarged view of the pawl gripping system shown in FIG. 1.

FIG. 4b is a perspective view of the spring bed.

FIG. 5a is a side cut-through view of an embodiment of a Running Tool Sub-Assembly, highlighting the hydraulic components.

FIG. 5b is a side cut-through view of an embodiment of a Running Tool Sub-Assembly, highlighting the finger collet for connecting to the Sacrificial Housing Sub-Assembly of FIG. 2a.

FIG. 6 is a side cut-through view of a delivery assembly comprising the Downhole Sealing Tool of FIG. 1, Sacrificial Housing Sub-Assembly of FIG. 2a, and the Running Tool Sub-Assembly of FIG. 5a-b.

DETAILED DESCRIPTION

Introduction

The present Downhole Sealing Tool may be used as a debris seal packer, for example, to connect a casing to a production liner. The Downhole Sealing Tool may be used as a liner hanger.

The Downhole Sealing Tool may be a Debris Seal Packer which acts as a barrier to large particulate matter that circulates in the wellbore. Most of this debris emanates from the production zone perforations in a well, can be as large as gravel, but mostly silt and sand coming from the oil-bearing formation. The purpose of the Debris Seal Packer is to reduce, or eliminate, particulate matter in circulation below the landing zone where the device is set.

The Downhole Sealing Tool may comprise one or more seals. An outer seal may be a skive-cut seal that expands radially against the bore of the casing. An inner seal adjacent to the outward seal may seal against the outer diameter of the Liner. Activating each seal requires a longitudinal, axial load to compress a set of multiple rings.

It will be appreciated that, for sealing the joint, the rings will most likely bulge on the outside of the cut to crush shut the skive cut, thereby sealing it. For example, if the cut is 0.010″ wide then the bulge may be at least 0.005″ on either side to close the gap.

Advantages of the present system include that the number of components on the Downhole Sealing Tool is relatively small, and it is easy to manufacture and assemble. It is also possible to adjust easily the forces applied by the seals.

Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present invention.

Downhole Sealing Tool—Debris Seal Packer

FIG. 1 shows an embodiment of a Downhole Sealing Tool 100. In this case, the Downhole Sealing Tool is a packer that comprises a tubular section 101 forming an enclosed channel and multiple seals 102, 103 (in this case, an inner seal 103 and an outer seal 102). It will be appreciated that other embodiments may comprise only a single seal on either the inside or the outside of the tubular section.

In this case, the tubular section comprises two cylindrical mounting surfaces: an outer mounting surface 105 which extends partially along the length of the channel from one end, and an inner cylindrical mounting surface 106 which extends partially along the length of the channel from the other end. In this case, in use, the outer mounting surface is towards the top of the Downhole Sealing Tool (closer to the surface within the well), and the inner mounting surface is towards the bottom of the Downhole Sealing Tool (away from the surface within the well).

The Downhole Sealing Tool also comprises multiple outer rings 102a,b,c,d,x,y,z mounted on the outer cylindrical mounting surface, and multiple inner rings 103a,b,c,d,e,w,x,y,z mounted on the inner cylindrical mounting surface.

The multiple outer rings comprise alternating outer deflection 102x-z and outer deformable 102a-d rings, and with the outer mounting surface 105, form an activatable outer seal.

The multiple inner rings comprise alternating inner deflection 103w-z and inner deformable 103a-e rings, and with the inner mounting surface 106, form an activatable inner seal.

In this embodiment, each of the inner and outer cylindrical mounting surfaces is bounded by a stop 107, 108 which limits the extent to which the mounted sets of rings can move along the mounting surface.

In the case of the outer seal, the stop 107 is in the form of an angled surface which is abutted by an end deformable ring 102d. When the set of rings are compressed, the end deformable ring 102d can expand away from the mounting surface by riding up on this complementary angled surface of the stop.

On the inner seal, the stop 108 surface abuts a deformable end ring 103e. In this case, the angle of the stop surface around 90° to allow for deformation of the abutting deformable end ring 103e.

It will be appreciated that, in other embodiments, the end ring may be a deflection ring, and the angle of the stop form an acute angle (e.g., less than) 90° with the mounting surface to prevent or restrict deformation of the abutting deflection end ring 103e.

It will be appreciated that either configuration would allow the deformable rings to deform away from the mounting surface under axial compression.

For each of the inner and outer sets of rings, each deflection ring has angled sides such that the deflection ring is wider towards the recessed cylindrical surface. Each deformable ring has angled sides complementary to the angled sides of the deflection rings such that the deformable ring is wider away from the recessed cylindrical surface.

In response to a set of multiple rings being axially compressed, each expandable ring in that set is pushed away from the recessed cylindrical surface by the complementary angled sides. The deflection rings 102x-z, 103w-z will move closer together along the respective cylindrical mounting surface.

As shown in the diagram, each ring is symmetrical about a mirror plane perpendicular to the tubular axis. Each ring is circularly symmetric about the tubular axis. Each ring has a trapezoidal cross-section in a plane through the central tubular axis. Each ring has a cylindrical inner surface. Each ring has a cylindrical outer surface. In the uncompressed configuration, the inner and outer surfaces of the deformable and deflection rings are aligned with each other.

In effect, the axial compression of a set of rings sets the seal. It will be appreciated that the outer rings in this example form an outer seal which can be used to seal the Downhole Sealing Tool to the interior wall of an outer tubular structure such as a well casing. The inner rings in this embodiment form an inner seal which can be used to seal the Downhole Sealing Tool to the exterior wall of an inner tubular structure such as a well liner. These seals will permit fluid to pass between the inner and outer tubular structures via the channel within the tubular section of the Downhole Sealing Tool itself.

In this embodiment, the rings are formed from metal (e.g., J55 or equivalent, K55 or equivalent, L80/4140, brass, copper, aluminium, or any malleable steel). This allows the Downhole Sealing Tool to form metal-to-metal seals which may be particularly important at high temperatures and pressures.

In some embodiments, the deformable rings may be formed from an elastomeric material. In some embodiments, there may be multiple deformable rings.

A deformable ring may comprise a plastically deformable ring. This may be useful where the surface that is being sealed on to is irregular, as the plasticity of the ring may allow it to adapt to the surface.

A deformable ring may comprise an elastically deformable ring. This may be useful where you may wish to repeatedly seal to a surface and then release the seal. Elastic deformation of the deformable rings can be reversed by allowing the set of rings to axially expand.

Sacrificial Housing Sub-Assembly

FIGS. 2a-c shows a sacrificial housing sub-assembly 230. In this example it consists of two components, an entry guide 232 and a piece of piping 231. FIG. 2a is a side cut-through view of an embodiment of a Sacrificial Housing Sub-Assembly. FIG. 2b is a side transverse cross-section view of the entry guide. FIG. 2c is a perspective view of an embodiment of a Sacrificial Housing Sub-Assembly.

In this case, the piece of piping 230 is a pup joint threaded at both ends. The bottom end of the pup joint will be threaded on to the liner when the liner and Downhole Sealing Tool is being installed into the well.

The upper end of the piece of piping is threaded onto the entry guide 232. The upper end of the entry guide has a flared inner surface 235 to help guide objects being passed downhole through the entry guide 232 into the piece of piping 231 and on into the liner. In this case, the entry guide comprises a recess 234 on a cylindrical inner surface 236. This recess will be discussed later with respect to the finger collet of the Running Tool (RT) Sub-assembly.

In this case, the flared surface 235 of the entry guide is axially traversed by multiple access channels 233a,b adjacent to the outer diameter of the entry guide. The access channels in this embodiment are in the form of slots or open channels on the outside of the entry guide. In this embodiment, as shown in FIG. 2b, the channel has a dovetailed cross section. The inwardly sloping sides of the channel help retain the pushrods within the channel. It will be appreciated that, in other embodiments, the access channels may be closed channels or holes. The flared surface 235 has a diameter greater than the outer diameter of the piece of piping 231. The access channels allow access to the outer diameter of the piece of piping 231 from within the flared surface 235 of the entry guide 232. These access channels will be discussed later with respect to the push rods (see FIG. 5a) of the Running Tool (RT) Sub-assembly which are used to activate the outer seal.

FIG. 3 shows a perspective view of the front half of a further embodiment of a sacrificial housing sub-assembly connected to the Downhole Sealing Tool. Like the embodiment of FIG. 2a, this embodiment comprises and entry guide 332 and a piece of piping. The entry guide in this case comprises a flared surface 335 to help guide objects through into the piece of piping. As with the embodiment of FIG. 2a, the entry guide also includes a series of access channels 333a,b through the flared surface to allow a push rod to access and activate the outer seal 102 from above the flared surface.

Attaching the Sacrificial Housing Sub-Assembly to the Downhole Sealing Tool

To attach the sacrificial housing sub-assembly to the Downhole Sealing Tool, the piece of piping 231 of the sacrificial housing sub-assembly 230 is inserted through the channel 109 of the Downhole Sealing Tool. This positions the outer surface of the piece of piping 231 within the inner seal 103.

For clarity, the bottom sub 121 and the end cap 122 of the Downhole Sealing Tool 100 of FIG. 1 is shown separately in FIG. 4a. In this embodiment, each of these components performs a distinct function.

In this embodiment, when the bottom sub 121 is screwed onto the Downhole Sealing Tool, the inner wall 127 of the bottom sub moves a spring bed 104 (shown in FIG. 1) along the cylindrical mounting surface 106 of the inner seal compressing the inner set of rings 103. This deforms the deformable rings 103a-e inwardly away from the mounting surface 106 to grip the outer surface of the piece of piping 231. The spring bed 104 is used in this embodiment to allow for the piece of piping to have a degree of ovality rather than being perfectly circular in cross section. As shown in FIG. 1, the spring bed 104 is mounted on the same mounting surface 106 as the rings 103.

In this case, as shown in FIG. 4b, the spring bed comprises two axially aligned rings connected with a plurality of springs. In other embodiments, the spring bed could also be an elastomer like a rubber bumper.

In this embodiment, as shown in FIG. 4a, as the end cap 122 is screwed onto the bottom sub 121, a split ring pawl 123 (in this case with serrated inner gripping edges) is moved along an angled inner surface of a pawl insert 124 which is mounted to the bottom sub 121. The pawl insert is in the form of a ring with a cylindrical outer surface and an inclined inner surface.

In this embodiment, when the pawl is driven into the outside surface of the piece of piping 231, this pawl 123 grips the outer surface of the piece of piping 231, in this embodiment, more tightly than the inner seal 103. The pawl insert 124 which is used to guide the pawl 123 and hold it in place is itself held in place using a shear ring 125 to prevent the pawl insert from moving axially within the bottom sub. It will be appreciated that other shear elements (e.g., a series of shear pins) may be used to hold the pawl insert in other embodiments.

As discussed below, this pawl shear ring 125 is configured to shear after the Downhole Sealing Tool has been fixed in place within the well, to release the more powerful pawl grip and allow the piece of piping to move up and down within the inner seal.

Running Tool Sub-Assembly

FIGS. 5a and 5b show different components of an embodiment of a Running Tool Sub-assembly 550 which is used to deliver the Downhole Sealing Tool 100 to the correct position within the well, and to set the outer seal 102, and then be removed. FIG. 5a highlights the hydraulic components of the Running Tool Sub-assembly, and FIG. 5b highlights mechanical connectors of the Running Tool Sub-assembly.

Regarding the mechanical connection, as shown in FIG. 5b, the Running Tool Sub-assembly comprises a finger collet 551 comprising multiple aligned fingers (e.g., 552) arranged around and attached to the circumference of a ring, each finger extending along a finger axis parallel to the tubular axis. Each finger comprises a smooth inner surface which extends along the finger's entire length. Each finger comprises a protuberance (e.g. 552a) on the outer surface at a distal end opposite the ring. When not engaged, the fingers are configured to be deformable (e.g. elastically) inward and/or outwards about the attached ends.

The Running Tool Sub-Assembly also comprises torque lugs (e.g., 553a) which correspond to corresponding torque lugs (234a,b) on the entry guide 232. When engaged, these torque lugs prevent or restrict axial rotation of the Running Tool Sub-Assembly with respect to the entry guide. This allows the rotation of the entry guide to be controlled by controlling the rotation of the Running Tool Sub-Assembly. In this embodiment, the torque lugs on the entry guide are recesses, and the torque lugs on the Running Tool Sub-Assembly are protuberances. It will be appreciated that, in other embodiments, the recesses may be provided on the Running Tool Sub-Assembly, with complementary recesses provided on the entry guide. Or in other embodiments, other complementary circularly asymmetric shapes may be used.

This finger collet 551 is inserted into the entry guide 232 (as shown in FIG. 2) and the protuberances 552a are configured to engage with the recess 234 within the entry guide.

The protuberances are trapped within the recess by inserting a cylindrical shear sleeve 554 (as shown in FIG. 5a) inside the finger collet 551 which abuts the smooth inner surfaces of the fingers, thereby restricting inward motion of the fingers. By trapping the figures, the Running Tool Sub-assembly can now carry the weight of the Downhole Sealing Tool, Sacrificial Housing Sub-assembly, and any connected components (e.g., such as the liner attached to the Sacrificial Housing Sub-assembly).

In this embodiment, the shear sleeve 554 is mounted towards the top of a tubular cylindrical shear sleeve guide 560 in a first position (as shown in FIG. 5a), and is connected to the shear sleeve guide using shear pins 561 to restrict movement of the shear sleeve down the shear sleeve guide towards a second position.

At the bottom end of the shear sleeve guide, this embodiment comprises a closeable seat 555. In this case, the seat is configured to receive a ball 556 which allows the interior of the Running Tool Sub-assembly to be pressurized upstream from the ball.

Using a sealable component, means that the release tool can allow the drilling fluid to flow through it to run in the liner. The ball will seal off the flow path which enables the use of drilling fluid to hydraulically set the seal stake and release off the tool. In other embodiments, a dart could also be used.

The seat 555, in this embodiment, also acts as a stop to prevent the sliding sleeve 554 coming off the sliding sleeve guide 560. It will be appreciated that, in other embodiments, other stops may be used to retain the sliding sleeve on the sliding sleeve guide.

As shown in FIG. 5a, the interior of the Running Tool Sub-assembly is connected to two hydraulic chambers: a pushrod hydraulic chamber 559 and a shear sleeve hydraulic chamber 562.

The pushrod hydraulic chamber 559 is configured to move pushrods 557a,b downwards to expand the deformable rings of the outer seal 102. The pushrods are elongate members, each pushrod extending in a direction along the tubular axis. When the Running Tool Sub-assembly 550 is connected to the Sacrificial Housing Sub-assembly 230 (as shown in FIG. 2), the pushrods 557a,b pass through the access channels 233a,b in the flared portion of the entry tool such that the ends engage with the upper surface of the outer set of rings 102.

Positioning and Setting the Tool

FIG. 6 shows the Delivery Assembly 190 which includes the connected Running Tool Sub-assembly 550, the Sacrificial Hoisting Sub-assembly 230 and the Downhole Sealing Tool 100. At the well site, this Delivery Assembly will, in this case, be connected to the liner at the bottom end, and to a delivery mechanism, such as coiled tubing or a production coil, at the top end to allow the Delivery Assembly to be lowered into the well. While the liner is being lowered, the weight of the liner is supported by the downhole tool through a combination of the inner seal and the pawl grip system.

When the Delivery Assembly is in position within the well, the interior of the Running Tool Sub-assembly 550 is sealed (e.g. using a ball 556 drop), and the pressure within the interior is increased to a first pushrod pressure (e.g., 2,000-5,000 psi). This pushrod pressure drives the pushrods 557a,b downwards onto the outer core 112 of the ratchet ring assembly. The reaction force to the pushrods moving downward is generated because the tubular section of the Downhole Sealing Tool 100 is rigidly attached to the piece of piping 231 (which cannot move down) by the pawl 123 which is engaged to the outer surface of the piece of piping. The push rods 557a,b move the outer core 112 of the ratchet ring downwards with respect to the inner core 113 of the ratchet ring which is connected to the tubular section 101. In this way, the outer core of the ratchet ring axially compresses the set of multiple outer rings. The ratchet ring 111 prevents the outer rings 102 from expanding when the pushrods 557a,b are subsequently removed.

In response to the multiple outer rings 102 being axially compressed, each outer deformable ring 102a-d is pushed away from the outer mounting surface 105 by the complementary angled sides of the deformable and deflecting rings 102a-d, 102x-z. This sets the outer seal as the outer deformable rings engage with the inner surface of the casing.

When the outer seal is set, the pressure within the interior is increased to a second sliding sleeve pressure (e.g., 3,500-10,000 psi). It will be appreciated that the sliding sleeve pressure may be at least 1,500 psi greater than the pushrod pressure to ensure that the components are activated in the correct sequence. This sliding sleeve pressure exerts a sufficient downward pressure on the sliding sleeve 554 (via the sliding sleeve hydraulic chamber) to shear the shear pins 561, thereby allowing the sliding sleeve 551 to move downwards along the sliding sleeve guide 560. This releases the fingers of the finger collet 552a such that they can move inwards away from the recess 234 of the entry guide of the Sacrificial Housing Sub-assembly 230.

The Running Tool 550 is now no longer connected to the Sacrificial Housing Sub-assembly 230, and the outer seal 102 holds the Downhole Sealing Tool 100 in position with respect to the casing. The Sacrificial Housing Sub-assembly is now free to be removed from the well.

In this configuration, the Downhole Sealing Tool 100 is rigidly connected to the outer casing using the outer seal 102, and to the piece of piping 231 using the inner seal 103 and the pawl grip 124.

To allow for thermal expansion and/or contraction of the liner, the pawl grip must be released. After being inserted, the liner will initially expand as the temperature downhole is always greater than at surface. In this case, as shown in FIG. 4, thermal expansion of the liner will force the pawl grip 124 upwards which will shear the shear ring 125 holding the pawl insert in place. With the pawl insert 124 free to move upwards, the pawl grip 123 will no longer be held inwards, and the pawl grip will release the grip on the liner. With this pawl grip being released, the liner will continue to be held and sealed by the inner seal rings.

After the shear ring 125, the shear ring, the pawl insert and/or the pawl grip may be received in a recess 126 within the pawl grip assembly 120.

Other Options

In the embodiment described above, the pawl system provides the reaction force to the push rods by fixing the tubular section of the Downhole Sealing Tool to the Sacrificial Housing Sub-Assembly (e.g., the piece of piping, the entry guide and/or the liner). An alternative to this is to have a releasable connection between the tubular section of the Downhole Sealing Tool and a component of the Sacrificial Housing Sub Assembly (e.g., the entry guide). The connection may be releasable as a result of an upward force being exerted on the Sacrificial Housing Sub-Assembly while the Downhole Sealing Tool is rigidly sealed to the inner diameter of the casing (e.g. through thermal expansion of the liner).

The releasable connection may comprise a threaded tubular connection which connects, for example, the inner core of the ratchet ring and the entry guide (e.g., at or adjacent to the bottom surface of the entry guide). When the push rods are activated, this threaded connection prevents the inner core of the ratchet ring (or the connected tubular section) from moving, while the outer core of the ratchet ring is moved downward to compress the outer seal.

Release may be effected in several ways. For example, the connection between the inner core of the ratchet ring and the entry guide may comprise a shear plane (e.g., a portion of a tube with a groove or serrations around it to weaken it at that position).

The shear plane may be sufficiently strong to hold the weight of the liner as the tool is being inserted into the well. The shear plane/weak point is there to hold the hanger in position while running into the hold and crushing the seals. It will be the connection between the re-entry guide and hanger. After the hanger is set and the running tool is removed from the well, the force from thermal expansion will shear the connection between the two allowing for the liner to slide through the hanger.

Other embodiments may comprise other release mechanisms based on: one or more of: rotation and/or translation of the string from the surface; and wireline control.

Other Uses

A packer comprising an axially activatable seal such as those described above may be used in a variety of packers including those configure to perform one or more of the following:

• • Prevent downhole movement of the tubing string, generating considerable axial tension or compression loads on the tubing string;
  • Support some of the weight of the tubing where there is significant compressive load on the tubing string;
  • Allows the optimum size of well flow conduit (the tubing string) to meet the designed production or injection flowrates;
  • Protect the production casing (inner casing string) from corrosion from produced fluids and high pressures;
  • Can provide a means of separating multiple producing zones;
  • Provided the tubing string and packer maintain integrity, well control is focused on the tubing flow, allowing the downhole safety valve to shut-off flow from the reservoir;
  • Hold well-servicing fluid (kill fluids, packer fluids) in the casing annulus; and
  • Facilitate artificial lift, such as continuous gas lifting through the A-annulus.

The downhole sealing tool may be used in one or more of: flow control device deployment, casing patch, liner patch, cement retainer, bridge plug, abandonments. The downhole sealing tool may be used for any application where one must hang or secure a pipe inside a pipe.

In Use

In this embodiment, the outer seal is configured to set at a greater pressure than the inner seal. This means that when the liner axially expands and contracts through temperature changes, the liner will slide within the Downhole Sealing tool preventing bending or collapse of the liner due to thermal deformation not having a controlled outlet.

It will be appreciated that, after the outer seal has been set, thermal expansion may cause the shear pin holding the pawl in place to be sheared, thereby permitting controlled thermal expansion and contraction of the liner within the inner seal.

Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.