Apparatus To Move An Object In An Open Hole Section of A Wellbore

This United States non-provisional patent application is a continuation-in-part of U.S. non-provisional patent application Ser. No. 17/800,252, filed Aug. 17, 2022, which is an application under 35 USC Sec. 371 of PCT/EP2021/055468, filed Mar. 4, 2021. Foreign priority is claimed to GB2003163.9, filed Mar. 5, 2020.

The present invention relates to methods and apparatus for wellbore operations such as fishing, re-completion and abandonment and in particular, though not exclusively, to a method and apparatus for tubing recovery.

In the course of constructing an oil or gas well, a hole is drilled to a pre-determined depth. The drilling string is then removed and a metal tubular or casing is run into the well and is secured in position using cement. This process of drilling, running casing and cementing is repeated with successively smaller drilled holes and casing sizes until the well reaches its target depth. At this point, a final tubular or tubing is run into the well referred to as a completion. The well is produced through the tubing.

In many deviated wells, and particularly in horizontal wells, the target depth represents the build section and the well is then drilled over the horizontal section. This lower section may be referred to as ‘open hole’ as it is too expensive and technically difficult to cement casing or other tubulars here. Thus, outer casing is run and cemented to a casing shoe located at the end of the build section where the well then has a horizontal section. The well is completed by running an inner tubular string into the deviated or horizontal open hole section of the well. The inner tubular string is typically held in place with packers which seal the annulus between the tubular string and the borehole wall. The inner tubular string may include frac sleeves and the like to access the formation in the open hole section.

When production becomes uneconomical in these wells, but there is still recoverable hydrocarbons present in the reservoir, the well can be re-completed. The lower completion in the open hole is removed and replaced. To remove the inner tubular string, it is cut and pulled in sections. The cutting and pulling of tubulars is a known technique in well abandonment. A cutting tool is run into the tubular string and cuts a section of tubing. The cut section of tubing is then gripped by a spear and pulled to surface. The spear can be considered as a pulling tool. Each trip into a well takes substantial time and consequently significant costs. Combined casing cutting and pulling tools have been developed so that the cutting and pulling can be achieved on a single trip. Such a tool is the TRIDENT® System to Ardyne Technologies Limited, UK.

US 2020/0224509 A1, the disclosure of which is incorporated herein in its entirety by reference, describes a cutting and pulling tool which advantageously has a cutting tool which can be operated by rotation of the work string while the pulling tool is anchored to the inside wall of the casing section above the cut to hold the casing in tension and provide stability to the cutting action. The pulling tool may be considered as an anchor or spear.

The casing is cut and pulled in sections to a desired depth and if one can pull long lengths of cut casing from the well this further reduces the number of trips required to achieve casing recovery. However, it is known that the presence of drilling fluid sediments, partial cement, sand, or other settled solids in the annulus between the outside of the casing and the inside of a surrounding outer casing can act as a binding material limiting the ability to free the casing when pulled.

Traditionally, cut casing is pulled by anchoring a casing spear to its upper end and using an elevator/top drive on a drilling rig. However, some drilling rigs have limited pulling capacity, and a substantial amount of power is lost to friction in the drill string between the top drive and the casing spear, leaving insufficient power at the spear to recover the casing.

Consequently, further trips must be made into the well to cut the casing into shorter lengths for multi-trip recovery.

To increase the pulling capability, a downhole power tool (DHPT) available from Ardyne Technologies Limited, UK, has been developed. After the casing has been located and engaged with a casing spear, hydraulically-set mechanically releasable slips anchor the DHPT to the wall of the larger outer casing above. A static pressure is applied to begin the upward movement of the cut casing, with the DHPT downhole multi-stage hydraulic actuator functioning as a hydraulic jack. After the stroke is completed, the anchors are released. The power section can be reset and the anchor re-engaged as many times as required. The DHPT is described in U.S. Pat. No. 8,365,826 B2 to the present Applicants, the disclosure of which is incorporated herein in its entirety by reference.

The combination of a cutting and pulling tool with a hydraulic jack is provided in the TITAN® system available from Ardyne Technologies Ltd, UK. It is described in US 2019/0257168 A1 to the present Applicants, the disclosure of which is incorporated herein in its entirety by reference.

For the removal of the tubing string in the open hole section of a well, a hydraulic jack is required as the tubular is fixed in place by the packers and other debris that has collected around the tubular string in the open hole. Typically, the downhole pulling tool is anchored to the outer cemented casing above the casing shoe and a fishing device in the form of a spear or overshot is connected to the upper end of the cut section of tubular in the open hole. The downhole pulling tool is then used to jack the cut section of tubular free to recover it.

However, as deeper sections of the inner tubular string are removed, the distance between the cut section of tubular and the outer casing can become significant. Applying the high forces at the downhole pulling tool to move a cut section of tubular results in the drill string between the tubular and the pulling tool to elongate. Sometimes the ‘stretch’ is so long that the stroke of the pulling tool is used up before sufficient force can be generated to release the cut section of tubular. Additionally, operating difficulties are found in pulling the drill string around the deviation or heel.

It is therefore an object of the present invention to provide a method to move an object in an open hole section of a wellbore which obviates or mitigates one or more disadvantages of the prior art.

It is a further object of the present invention to provide apparatus to move an object in an open hole section of a wellbore which obviates or mitigates at least one disadvantage of the prior art.

According to a first aspect of the present invention there is provided a method to move an object in an open hole section of a wellbore, comprising the steps:

In this way, by anchoring the downhole pulling tool in the open hole section it can be close to the object so that the pulling force is directly applied to the object without elongating the drill string between the downhole pulling tool and the object. Preferably the steps are completed in order. More preferably the steps are completed on a single trip in the well. Preferably, in step (b), in running the work string in the wellbore and the downhole assembly into the open hole section, the downhole assembly will be run through cased section of the wellbore. More preferably, the cased section comprises casing cemented in place. The cased section may be considered as the upper completion and the open hole section as the lower completion.

Preferably at step (g) the object is removed from the wellbore on the work string. Preferably, the object is a cut section of tubular. In this way, the inner liner string can be removed for a well to be re-completed or abandoned. Alternatively, the object is a downhole component such as a valve. In this way, any part of the lower completion can be removed using the downhole assembly. The object may be an actuator. In this way, the actuator can be moved to operate a tool such as a valve in a downhole completion. This the method can be used in well procedures such as fishing, re-completion and abandonment.

Preferably, the elastomeric anchor element is a packer element and step (d) comprises inflating the packer element to contact the wall and step (f) comprises deflating the packer element to disengage from the wall of the open hole section. Additionally, step (d) may comprise engaging the wall with at least one gripping element of the downhole assembly and step (f) comprises releasing the gripping element from the wall of the open hole section. In this way, open hole packers can be used. Preferably the open hole packer is retrievable. More preferably, the open hole packer is resettable so that it may be set and unset multiple times on a single trip in the well. As no seal is required between the downhole assembly and the wall of the open hole section, an anchor can be used at step (d). Such an anchor would include the one or more gripping elements. The gripping element may be a slip in a slip assembly. More preferably, the gripping element provides sufficient friction or grip to hold the assembly in place while the packer is set.

Preferably, the downhole assembly is configured for a grip force in anchoring the assembly to the wall of the open hole section to be greater than a pull force of the assembly on the object. The downhole assembly may be operated hydraulically by pumping fluid through the work string from surface. The grip force of the packer used to anchor the assembly and the pull force of the downhole assembly are both proportional to the pressure applied. By configuring the assembly such that the packer grip force is always higher than the pull force, the downhole assembly cannot stroke before the packer gets enough grip to prevent the packer sliding down the hole as you stroke the assembly, instead of the object moving up hole.

Preferably, the method includes an additional step of jetting fluid from the downhole assembly to wash the wall of the open hole section against which the downhole assembly will be anchored. In this way, the wall is prepared so that the packer will have a clean surface, free of debris, to set against. Preferably, the method includes an additional step of jetting fluid from the downhole assembly to wash an inner surface of the object before the fishing device grips the object. In this way, the inner surface of tubing is cleaned of debris so that a spear can engage the tubing more effectively.

Preferably, step (c) is achieved as the fishing device is a spear, a grapple or an overshot.

The method may include the additional steps, between steps (f) and (g), of raising the work string to move the downhole pulling tool until movement is prevented as the object remains stuck; re-anchoring the downhole assembly to the wall of the open hole section; operating the downhole pulling tool to pull the object; and releasing the downhole assembly from the wall of the open hole section. In this way, the downhole pulling tool can be used again on a single trip to sequentially pull the object to obtain a gradual release of the object. In this way, cut sections of tubular which have packers located thereon can be removed from the wellbore. Additionally, if the object sticks at any point as its being POOH, these additional steps can be used to free it so that it can be removed.

The method may include the additional steps, between steps (f) and (g), of raising the work string to move the downhole pulling tool until movement is prevented as the object is stuck; re-anchoring the downhole assembly to a wall of outer casing located uphole of the open hole section; operating the downhole pulling tool to pull the object; and releasing the downhole assembly from the wall of outer casing. In this way, the downhole pulling tool can additionally be used to free the object if it sticks when the downhole pulling tool is no longer in the open section. This may be needed when pulling a length of cut section of tubular around the heel or other deviation on the well.

The method may include the additional steps of including a cutting tool in the downhole assembly at step (a) and using the cutting tool to cut the object free from any attachment in the open hole section. When the object is a cut section of tubular, the cutting tool is used to cut the tubular to form the cut section of tubular. The step of cutting the tubular may be performed between steps (b) and (c). Alternatively, the step of cutting the tubular may be performed between steps (c) and (d). In this way fishing device can be used to stabilise the cutting tool during the cut and place the tubular in tension for the cut. Optionally, the step of cutting the tubular may be performed between steps (d) and (e). In this way the work string is anchored to the wellbore to assist in stabilising the structure during the cut and place the tubular in tension for the cut.

According to a second aspect of the present invention there is provided apparatus to move an object from an open hole section of a wellbore, comprising a string for running into the well, the string being arranged to carry a fluid in a throughbore thereof and including a downhole assembly, the downhole assembly comprising:

In this way, the downhole pulling tool can operate as a hydraulic jack in an open hole section of a wellbore to move an object. In an embodiment, the downhole pulling tool can operate as a hydraulic jack in an open hole section of a wellbore to pull a cut section of tubular.

Preferably, the open hole anchor is re-settable. In this way, the downhole pulling tool can be released, moved and re-anchored in the open hole section to operate multiple times on a single trip in the wellbore while being retrievable. Preferably, the anchor comprises an inflatable packer element. More preferably, the packer element is inflated by the fluid in the throughbore. As the packer element does not have to create a seal and does not have to remain in the well, a rubber inflatable sealing element can be used which provides sufficient change in diameter to span the annulus between the work string and the borehole wall. Alternatively or additionally, the anchor comprises at least one gripping element to engage the borehole wall in the open hole section. The gripping element may be a slip in a slip assembly, however sufficient travel is required to move the gripping surface of the element across the annulus between the tool body and borehole wall.

Preferably, the downhole pulling tool includes a housing supported in the well by the string and enclosing a plurality of axially stacked pistons generating a cumulative axial force, each of the plurality of pistons axially movable in response to the fluid increase in the throughbore; and wherein movement of the pistons also moves the inner mandrel.

Preferably, the downhole pulling tool is configured for a grip force in anchoring the pulling tool to the wall of the open hole section to be greater than a pull force of the inner mandrel on the object. The grip force of the packer used to anchor the assembly and the pull force of the downhole assembly are both proportional to the fluid pressure applied. By configuring the pulling tool such that the packer grip force is always higher than the mandrel pull force, the downhole pulling tool cannot stroke before the packer gets enough grip to prevent the packer sliding down the hole as you stroke the assembly, instead of the object moving up hole.

Preferably the fishing device comprises a spear. In this way, the spear can grip an inner surface of a tubular object such as a cut section of tubular. Alternatively, the fishing device may be an overshot. In this way, the overshot encompasses at least part of the object and grips it. An overshot can grip smaller diameter tubing in which a spear may not fit and/or provide sufficient gripping area. A grapple or an anchor may also be used.

In an embodiment, the spear comprises: a sliding assembly mounted on the inner mandrel; at least one gripper for gripping onto an inner wall of a cut section of tubular, the gripper being coupled to the sliding assembly; the sliding assembly being operable for moving the gripper between a first position in which the gripper is arranged to grip onto the inner wall of the cut section of tubular in at least one gripping region of the cut section of tubular and a second position in which the gripper is held away from the inner wall; and a switcher which, when advanced into the cut section of tubular, locks the sliding assembly to the inner mandrel with the gripper in the second position; and, when the casing spear is pulled upward out of the cut section of tubular and the switcher exits the end of the cut section of tubular, automatically allows engagement of the cut section of tubular by the gripper in the first position. In this way, the cut section of tubular is automatically gripped into engagement with the spear when the spear is at the top of the cut section of tubular. Preferably the spear is the FRM Spear supplied by Ardyne AS.

Preferably, the downhole assembly includes a jetting tool, to jet fluid from the downhole assembly. More preferably, the jetting tool has a plurality of circumferentially arranged jetting ports on a tubular body. In this way, the wall of the open hole section can be cleaned to assist in setting the packer without requiring rotation of the work string.

Preferably, the downhole assembly includes a valve for blocking the flow of fluid through the throughbore, the valve being located between the downhole pulling tool and the spear, wherein the valve is closed by raising the downhole pulling tool relative to the spear when the spear engages the cut section of tubular and opened by setting pressure down on the downhole pulling tool. In this way, the fluid pressure can be increased in the throughbore to operate the downhole pulling tool when required. Preferably the valve is the ALO valve supplied by Ardyne AS.

The downhole assembly may further comprise a cutting tool to cut a tubular and form a cut section of tubular as the object. Preferably the cutting tool is a casing cutter as is known in the art.

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.

Reference is initially made to Figure of the drawings which illustrates apparatus, generally indicated by reference numeral, for removing an objectfrom an open hole sectionof a wellboreaccording to an embodiment of the present invention. The apparatusis located in the wellbore.

Wellboremay be a vertical, horizontal or deviated well. In the example shown in, the wellborewas completed using a casing stringwhich is typically run from surface (not shown) to a downhole location at the heelof the wellbore. The casingis cementedin place, as is known in the art of well construction. The wellbore may then have been completed by drilling a boreholeand hanging a liner, or other tubular, from the casing shoeat the heel. The linerwas held in place by packersarranged along the length of the liner. Completion tools such as frac valves or sand screens may have been located between the packers. In, a section of the linerhas already been removed from the well from the heelto the location of the packer. This removal will have been completed by known casing recovery techniques. These casing recovery techniques would rely on anchoring removal apparatus to the inner wallof the casing string. Operating any tools from a distant anchor point can cause elongation or reduced torqueing on the drill string therebetween which limits the operation of such tools. Thus, recovery of the linerbecomes difficult at distances further from the casing. This is further hampered by the packers or other equipment, together with sand and debris, which can be holding the linerin place. While a lower completion of liner and packersis illustrated, it will be appreciated that any arrangement in which a borehole is drilled to form an open hole section, where the boreholewallis exposed i.e. there is no cemented casing string, could be used. The objectis shown as the end of a liner, however, the object may be any objectlocated in the open hole sectionsuch as other downhole components such as a valve, or an actuator of a downhole component for which movement thereof will cause an operation to be performed by the component e.g. moving a sliding sleeve to open a valve.

Referring to, apparatuscomprises a work stringwhich may be a drill string comprised of drill pipe sections run from surface, through which fluid can flow in a throughborethereof. A bottom hole assemblyis located at the endof the work string. The bottom hole assemblymay comprise in order from the end, a fishing device(an overshot), a jetting tool, a valveand a downhole pulling toolmade up of an open hole anchorand an actuator system. Valveis shown in the mandrelof the pulling toolbut could be in the throughboreanywhere below the pulling tool. Adjacent parts of the assemblymay be formed integrally on a single tool body or may be constructed separately and joined together by box and pin sections as is known in the art. Two or more parts may also be integrally formed and joined to any other part. Further parts may be included and drill pipe sections can be inserted between parts to provide a desired spaced apart relationship between the component parts. The work stringis typically run from a rig (not shown) via a top drive/elevator system which can raise and lower the stringin the wellbore.

The downhole pulling toolcan be considered as a hydraulic jack and has an open hole anchorand an actuator systemwhich pulls the inner mandrelup into a housingof the tool. The downhole pulling toolmay be a modification of the DHPT available from Ardyne AS. It is described in U.S. Pat. No. 8,365,826 B2, the disclosure of which is incorporated herein in its entirety by reference.

Referring to, the open hole anchormay be any arrangement of known open hole anchor but is preferably operated by fluid pressure in the throughbore. The open hole anchorincludes an elastomeric anchor element. In a preferred embodiment the elastomeric anchor elementis an inflatable packer which uses fluid from the throughboreto fill a rubber bladder so as to expand and adhere to the borehole wall. By reducing the fluid pressure in the throughborethe packermay be deflated so as to be retrievable and re-settable in the wellbore. The packeris used to hold the assemblyto the borehole walland thus does not need to create a seal. As the packersuse is also temporary, a rubber bladder will be suitable as the packer is not left downhole for isolation purposes.

Gripping elementsmay also be present to assist in anchoring the assemblyto the borehole wallof the open hole sectionto allow the open hole packerto set. While traditional slips could be used, it is likely that the gripping elementswill require to have a greater degree of travel to be able to span the annulusand contact the borehole wall. As the open hole anchoris to be retrievable, the gripping elementsneed to be retractable and also preferably fluid operated. If used with a packer, the gripping elementsneed not fully anchor to the borehole wall, but just provide sufficient hold for the packerto be set.

Referring to, the downhole pulling toolalso has an actuator system. This is as described in U.S. Pat. No. 8,365,826 B2, the disclosure of which is incorporated herein by reference. The actuator systemhas an outer housingconnected to the work stringand an inner mandrelextending from the tool. Inside the housing, the mandreland housinghave an array of stacked pistonsarranged therebetween. Fluid from the throughboreenters a chamberbetween each pair of pistons and causes movement of the inner mandrelrelative to the static housing(anchored to the borehole wallby virtue of the anchor) to move the inner mandrelinto the housingand so raise or pull any object connected to the mandrel. In, the remaining elements of the bottom hole assemblyare connected to the inner mandrel. The movement of a piston across a chamber to meet a neighbouring piston constitutes a stroke of the pulling tool. As there are multiple stacked pistons, the combined cross-sectional areas of the end faces when fluid pressure is applied generates a considerable lifting force via the inner mandrel.

The pulling toolis configured to operate the open hole anchorahead of the actuator system. This creates the pulling action. The downhole pulling toolis configured such that the grip force of the anchor is greater than the pull force on the object. The grip force of the packer used to anchor the assembly and the pull force of the downhole assembly are both proportional to the fluid pressure applied. By configuring the pulling tool such that the packer grip force is always higher than the mandrel pull force, the downhole pulling tool cannot stroke before the packer gets enough grip to prevent the packer sliding down the hole as you stroke the assembly, instead of the object moving up hole.

When fluid pressure is reduced, the anchor will unset, by virtue of the packerbeing retrievable, and the fluid will exit the chambers so as to allow the pistons to return to their initial positions, at the opposite end of the stroke as the work stringis raised. The raising of the work stringrepositions the pulling toolat a location higher up in the wellbore. Fluid pressure in the throughborecan be increased again and the process repeated to sequentially anchor the tooland pull an object attached to the inner mandrel, any number of times, to move the object. Once the object is free, pulling the work stringshould be able to pull the bottom hole assemblyand the object, in this case a cut section of liner, to surface for recovery.

Referring to, to provide the increase in fluid pressure in the throughbore, a valveis located below the pulling tool, in the mandrel. In, the valveis illustrated as sitting directly below the housing, however the valvemay be positioned in any part of the mandrel below the pulling tool, its position being determined by other tools on the string. A suitable valveis described in U.S. Pat. No. 8,365,826 B2 being a ball valve operated via a drop ball. In a preferred embodiment, an ALO valve as supplied by Ardyne AS is used. The ALO valve is designed to form part of mandrel, and in which a valve is provided with a passage for fluid, the passage including an opening and closing mechanism. In use: a first valve portion is connected to the mandrel; second valve portion telescopic relative to the first valve portion is connected to a fishing device(overshot); in an initial position, the first valve portion and the second valve portion are held together under the force of a spring and arranged so that the opening and closing mechanism is open; pulling the mandrelmoves the first valve portion relative to the second valve portion thereby extending the valve to close the opening and closing mechanism. Thus the valveadvantageously can be cycled between open and closed positions by applying tension to the mandrelon which the upper portion of the valve is attached. The ALO valve is described in US 2016/0273307 A1, the disclosure of which is incorporated herein in its entirety by reference.

In embodiments shown in, the fishing deviceis an overshot. These are known and comprise a barrel arrangement which fits over the object, typically a tubular. A friction device in the overshot, usually either a basket or a spiral grapple, firmly grips the outer surface of the tubular, allowing the tubular to be pulled. The fishing devicemay be any known device such as a grapple, anchor or spear.

Also shown inis a jetting tool. Jetting toolhas a tubular body and a plurality of portsthrough which washing fluid passed down the throughboreis ejected. The portsare arranged around the tool body to provide 360 degree coverage. Nozzles may be located in the portsto increase the speed of the fluid, so that it crosses the annulusand impacts the inner wallof the open hole section. This allows the wallto be cleared of sand and other debris which may prevent the packermaking a strong contact to the wall.