Patent Application
20100252278
The present invention relates to downhole tools used in oil and gas well drilling operations and, more particularly, to an anchor for well liners and other downhole tools and to tools and methods for inserting and setting the anchor.
Hydrocarbons, such as oil and gas, may be recovered from various types of subsurface geological formations. The formations typically consist of a porous layer, such as limestone and sands, overlaid by a nonporous layer. Hydrocarbons cannot rise through the nonporous layer, and thus, the porous layer forms a reservoir in which hydrocarbons are able to collect. A well is drilled through the earth until the hydrocarbon is bearing formation is reached. Hydrocarbons then are able to flow from the porous formation into the well.
In what is perhaps the most basic form of rotary drilling methods, a drill bit is attached to a series of pipe sections referred to as a drill string. The drill string is suspended from a derrick and rotated by a motor in the derrick. As the drilling progresses downward, the drill string is extended by adding more pipe sections.
A drilling fluid or “mud” is pumped down the drill string, through the bit, and into the well bore. This fluid serves to lubricate the bit and carry cuttings from the drilling process back to the surface. As a well bore is drilled deeper and passes through hydrocarbon producing formations, however, the production of hydrocarbons must be controlled until the well is completed and the necessary production equipment has been installed. The drilling fluid also is used to provide that control. That is, the hydrostatic pressure of drilling fluid in the well bore relative to the hydrostatic pressure of hydrocarbons in the formation is adjusted by varying the density of the drilling fluid, thereby controlling the flow of hydrocarbons from the formation.
When the drill bit has reached the desired depth, larger diameter pipes, or casings, are placed in the well and cemented in place to prevent the sides of the borehole from caving in. The casing then is perforated at the level of the oil bearing formation so oil can enter the cased well. If necessary, various completion processes are performed to enhance the ultimate flow of oil from the formation. The drill string is withdrawn and replaced with a production string. Valves and other production equipment are installed in the well so that the hydrocarbons may flow in a controlled manner from the formation, into the cased well bore, and through the production string up to the surface for storage or transport.
This simplified drilling process, however, is rarely possible in the real world. For various reasons, a modern oil well will have not only a casing extending from the surface, but also one or more pipes, i.e., casings, of smaller diameter running through all or a part of the casing. When those “casings” do not extend all the way to the surface, but instead are mounted in another casing, they are referred to as “liners.” Regardless of the terminology, however, in essence the modern oil well typically includes a number of tubes wholly or partially within other tubes.
Such “telescoping” tubulars, for example, may be necessary to protect groundwater from exposure to drilling mud. A liner can be used to effectively seal the aquifer from the borehole as drilling progresses. Also, as a well is drilled deeper, especially if it is passing through previously depleted reservoirs or formations of differing porosities and pressures, it becomes progressively harder to control production throughout the entire depth of the borehole. A drilling fluid that would balance the hydrostatic pressure in a formation at one depth might be too heavy or light for a formation at another depth. Thus, it may be necessary to drill the well in stages, lining one section before drilling and lining the next section. Portions of existing casing also may fail and may need to be patched by installing liners within damaged sections of the casing.
The traditional approach to installing a liner in an existing casing has been to connect or “tie” the liner into an anchor, that is, a “liner hanger.” Conventional anchors have included various forms of mechanical slip mechanisms that are connected to the liner. The slips themselves typically are in the form of cones or wedges having teeth or roughened surfaces. The typical hanger will include a relatively large number of slips, as many as six or more. A running and/or setting tool is used to position the anchor in place and drive the slips from their initial, unset position, into a set position where they are able to bite into and engage the existing casing. The setting mechanisms typically are either hydraulic, which are actuated by increasing the hydraulic pressure within the tool, or mechanical, which are actuated by rotating, lifting, or lowering the tool, or some combination thereof.
Such mechanical slip hangers may be designed to adequately support the weight of long liners. In practice, however, the wedges, cones, and the like that are intended to grip the existing casing may partially extend as the tool is run through existing casing and can cause the hanger to get stuck. They also may break off and interfere with other tools already in the well or make it difficult to run other tools through the casing at a later time. Moreover, separate “packers” must be used with such anchors if a seal, is required between the liner and the existing casing.
One approach to avoiding such problems has been to eliminate in a sense the anchor entirely. That is, instead of tying a liner into an anchor, a portion of the liner itself is expanded into contact with an existing casing, making the liner essentially self-supporting and self-sealing. Thus, the liner conduit is made of sufficiently ductile metal to allow radial expansion of the liner, or more commonly, a portion of the liner into contact with existing casing. Various mechanisms, both hydraulic and mechanical, are used to expand the liner. Such approaches, however, all rely on direct engagement of, and sealing between the expanded liner and the existing casing.
For example, U.S. Pat. No. 6,763,893 to B. Braddick discloses a patch liner assembly that is used, for example, to repair existing casing. The patch assembly comprises a pair of expandable conduits, that is, an upper expandable liner and a lower expandable liner. The expandable liners are connected to the ends of a length of “patch” conduit. The patch assembly is set within the casing by actuating sets of expanding members that radially expand a portion of each expandable liner into engagement with the casing. Once expanded, the expanded portion of the liners provide upper and lower seals that isolate the patched portion of the existing casing. The expanded liners, together with the patch conduit, thereafter provide a passageway for fluids or for inserting other tubulars or tools through the well.
U.S. Pat. No. 6,814,143 to B. Braddick and U.S. Pat. No. 7,278,492 to B. Braddick disclose patch liner assemblies which, similar to Braddick '893, utilize a pair of expandable liners connected via a length of patch conduit. The upper and lower liners are expanded radially outward via a tubular expander into sealing engagement with existing casing. Unlike the expanding members in Braddick '893, however, the tubular expanders disclosed in Braddick '143 and '492 are not withdrawn after the liner portions have been expanded. They remain in the expanded, set liner such that they provide radial support for the expanded portions of the liner.
U.S. Pat. No. 7,225,880 to B. Braddick discloses an approach similar to Braddick '143 and '492, except that it is applied in the context of extension liners, that is, a smaller diameter liner extending downward from an existing, larger diameter casing. An is expandable liner is expanded radially outward into sealing engagement with the existing casing via a tubular expander. The tubular expander is designed to remain in the liner and provide radial support for the expanded liner.
U.S. Pat. No. 7,387,169 to S. Harrell et al. also discloses various methods of hanging liners and tying in production tubes by expanding a portion of the tubular via, e.g., a rotating expander tool. All such methods rely on creating direct contact and seals between the expanded portion of the tubular and the existing casing.
Such approaches have an advantage over traditional mechanical hangers. The external surface of the liner has no projecting parts and generally may be run through existing conduit more reliably than mechanical liner hangers. The expanded liner portion also not only provides an anchor for the rest of the liner, but it also creates a seal between the liner and the existing casing, thus reducing the need for a separate packer. Nevertheless, they suffer from significant drawbacks
First, because part of it must be expandable, the liner is necessarily is fabricated from relatively ductile metals. Such metals typically have lower yield strengths, thus limiting the amount of weight and, thereby, the length of liner that may be supported in the existing casing. Shorter liner lengths, in deeper wells, may require the installation of more liner sections, and thus, significantly greater installation costs. This problem is only exacerbated by the fact that expansion creates a weakened area between the expanded portion and the unexpanded portion of the liner. This weakened area is a potential failure area which can damage the integrity of the liner.
Second, it generally is necessary to expand the liner over a relatively long portion in order to generate the necessary grip on the existing casing. Because it must be fabricated from relatively ductile metal, once expanded, the liner portion tends to relax to a greater degree than if the liner were made of harder metal. This may be acceptable when the load to be supported is relatively small, such as a short patch section. It can be a significant limiting factor, however, when the expanded liner portion is intended to support long, heavy liners.
Thus, some approaches, such as those exemplified by Braddick '143 and '492, utilize expanders that are left in the liner to provide radial support for the expanded portion of the liner. Such designs do offer some benefits, but the length of liner which must be expander still can be substantial, especially as the weight of the liner string is increased. As the length of the area to be expanded increases the forces required to complete the expansion generally increase as well. Thus, there is progressively more friction between the expanding tool and the liner being expanded and more setting force is required to overcome that increasing friction. The need for greater setting forces over longer travel paths also can increase the chances that liner will not be completely set.
Moreover, the liner necessarily must have an external diameter smaller than the internal diameter of the casing into which it will be inserted. This clearance, especially for deep wells where a number of progressively smaller liners will be hung, preferably is as small as possible so as to allow the greatest internal diameter for the liner. Nevertheless, if the tool is to be passed reliably through existing casing, this clearance is still relatively large, and therefore, the liner portion is expanded to a significant degree.
Thus, it may not be possible to fabricate the liner from more corrosion resistant alloys. Such alloys typically are harder and less ductile. In general, they may not be expanded, or expanded only with much higher force, to a degree sufficient to close the gap and grip the existing casing.
Another reality facing the oil and gas industry is that most of the known shallow reservoirs have been drilled and are rapidly being depleted. Thus, it has become necessary to drill deeper and deeper wells to access new reserves. Many operations, such as mounting a liner, can be practiced with some degree of error at relatively shallow depths. Similarly, the cost of equipment failure is relatively cheap when the equipment is only a few thousand feet from the surface.
When the well is designed to be 40,000 feet or even deeper, such failures can be to costly in both time and expense. Apart from capital expenses for equipment, operating costs for modern offshore rigs can be $500,000 or more a day. There is a certain irony too in the fact that failures are not only more costly at depth, but that avoiding such failures is also more difficult. Temperature and pressure conditions at great depths can be extreme, thus compounding the problem of designing and building tools that can be installed and will function reliably and predictably.
In particular, hydraulic actuators are commonly employed in downhole tools to generate force and movement, especially linear movement within the tool as may be required to operate the tool. They typically include a mandrel which is connected to a work string. A stationary piston is connected to the mandrel, and a hydraulic cylinder is mounted on, and can slide over the mandrel and the stationary piston. The stationary piston divides the interior of the cylinder into two hydraulic chambers, a top chamber and a bottom chamber. An inlet port allows fluid to flow through the mandrel into the bottom hydraulic chamber, which in turn urges the cylinder downward and away from the stationary piston. As the cylinder moves downward, fluid is able to flow out of the top hydraulic chamber via an outlet port. The movement of the cylinder then may be used to actuate other tool components.
Hydraulic actuators, therefore, can provide an effective mechanism for creating relative movement within a tool, and they are easily actuated from the surface simply by increasing the hydraulic pressure within the tool. Such actuators, however, can be damaged by the hostile environment in which they must operate. The hydrostatic pressures encountered in a well bore can be extreme and imbalances between the pressure in the mandrel and outside the actuator are commonly encountered. If the ports are closed while the tool is being run into a well, such pressure differentials will not cause unintended movement of the actuator, but they can impair subsequent operation of the actuator by deforming the actuator cylinder. Such problems can be avoided by immobilizing the cylinder through other means and simply leaving the ports open to avoid any imbalance of hydrostatic pressure that might deform the actuator cylinder. Fluids in a well bore, however, typically carry a large amount of gritty, gummy debris. The ports and hydraulic chambers in the actuator, therefore, typically are filled with heavy grease before they are run into the well. Nevertheless, the tool may be exposed to wellbore fluid for prolonged periods and under high pressure, and debris still can work its way into conventional actuators and impair their operation.
The increasing depth of oil wells also means that the load capacity of a connection between an existing casing and a liner, whether achieved through mechanical liner hangers or expanded liners, is increasingly important. Higher load capacities may mean that the same depth may be reached with fewer liners. Because operational costs of running a drilling rig can be so high, significant cost savings may be achieved if the time spent running in an extra liner can be avoided.
Ever increasing operational costs of drilling rigs also has made it increasingly important to combine operations so as to reduce the number of trips into and out of a well. For example, especially for deep wells, significant savings may be achieved by drilling and lining a new section of the well at the same time. Thus, tools for setting liners have been devised which will transmit torque from a work string to a liner. A drill bit is attached to the end of the liner, and the liner is rotated.
Torque is typically transmitted through the tool by a serious of tubular sections threaded together via threaded connectors. The rotational forces transmitted through the tool, however, can be substantial and can damage threaded connections by over-tightening the threads. In addition, it often is useful to rotate opposite to the threads. Such reverse, or “left-handed” rotation may be useful in the actuation and operation of various mechanisms, but it can loosen the connection. In either event, if connections in the torque transmitting components are impaired, it may be difficult or impossible to operate the tool. Set screws, pins, keys, and the like, therefore, have been used to secure a connector, but such approaches are susceptible to failure.
Such disadvantages and others inherent in the prior art are addressed by the subject invention, which now will be described in the following detailed description and the appended drawings.
The subject invention provides for anchor assemblies that are intended for installation within an existing conduit. The novel anchor assemblies comprise a nondeformable mandrel, an expandable metal sleeve, and a swage. The expandable metal sleeve is carried on the outer surface of the mandrel. The swage is supported for axial movement across the mandrel outer surface from a first position axially proximate to the sleeve to a second position under the sleeve. The movement of the swage from the first position to the second position expands the sleeve radially outward into contact with the existing conduit.
Preferably, the swage of the novel anchor assemblies has an inner diameter substantially equal to the outer diameter of the mandrel and an outer diameter greater than the inner diameter of the expandable metal sleeve. The mandrel of the novel anchor assemblies preferably is fabricated from high yield metal alloys and, most preferably, from corrosion resistant high yield metal alloys.
The novel anchor assemblies are intended to be used in combination with a tool for installing the anchor in a tubular conduit. The anchor and tool assembly comprises the anchor assembly, a running assembly, and a setting assembly. The running assembly releasably engages the anchor assembly. The setting assembly is connected to the running assembly and engages the swage and moves it from its first position to its second position.
As will become more apparent from the detailed description that follows, once the sleeve is expanded, the mandrel and swage provide radial support for the sleeve, thereby enhancing the load capacity of the novel anchors. Conversely, by enhancing the radial support for the sleeve, the novel anchors may achieve, as compared to expandable liners, equivalent load capacities with a shorter sleeve, thus reducing the amount of force required to set the novel anchors. Moreover, unlike expandable liners, the mandrel of the novel anchor assemblies is substantially nondeformable and may be made from harder, stronger, more corrosion resistant metals.
In other aspects the subject invention provides for novel clutch mechanisms which may be and preferably are used in the mandrel of the novel anchor and tool assemblies and in other sectioned conduits and shafts used to transmit torque. They comprise shaft sections having threads on the ends to be joined and prismatic outer surfaces adjacent to their threaded ends. A threaded connector joins the threaded ends of the shaft sections. The connector has axial splines. A pair of clutch collars is slidably supported on the prismatic outer surfaces of the shaft sections. The clutch collars have prismatic inner surfaces that engage the prismatic outer surfaces of the shaft sections and axial splines that engage the axial splines on the threaded connector. Preferably, the novel clutch mechanisms also comprise recesses adjacent to the mating prismatic surfaces that allow limited rotation of the clutch collars on the prismatic shaft sections to facilitate engagement and disengagement of the mating prismatic surfaces. Thus, as will become more apparent from the detailed description that follows, the novel clutch mechanisms provide reliable transmission of large amounts of torque through sectioned conduits and other drive shafts without damaging the threaded connections.
In yet other aspects, the subject invention provides for novel hydraulic actuators and hydraulic setting assemblies. The novel hydraulic actuators include a balance piston. The balance piston is slidably supported within the top hydraulic chamber of the actuator, preferably on the mandrel. The balance piston includes a passageway extending axially through the balance piston. Fluid communication through the piston and between its upper and lower sides is controlled by a normally shut valve in the passageway. Thus, in the absence of relative movement between the mandrel and the cylinder, the balance piston is able to slide in response to a difference in hydrostatic pressure between the outlet port, which is on one side of the balance piston, and the portion of the top hydraulic chamber that is on the bottom side of the balance piston. Thus, as explained in further detail below, the novel actuators are less susceptible to damage caused by differences in the hydrostatic pressure inside and outside of the actuator. Moreover, the balance piston of the novel actuators is able to prevent the ingress of debris into the actuator.
Those and, other aspects of the invention, and the advantages derived therefrom, are described in further detail below.
Those skilled in the art will appreciate that line breaks along the vertical length of the tool may eliminate well known structural components for inter connecting members, and accordingly the actual length of structural components is not represented.
The anchor assemblies of the subject invention are intended for installation within an existing conduit. They comprise a nondeformable mandrel, an expandable metal sleeve, and a swage. The expandable metal sleeve is carried on the outer surface of the mandrel. The swage is supported for axial movement across the mandrel outer surface from a first position axially proximate to the sleeve to a second position under the sleeve. The movement of the swage from the first position to the second position expands the sleeve radially outward into contact with the existing conduit.
The novel anchor assemblies are intended to be used in combination with a tool for installing the anchor in a tubular conduit. The anchor and tool assembly comprises the anchor assembly, a running assembly, and a setting assembly. The running assembly releasably engages the anchor assembly. The setting assembly is connected to the running assembly and engages the swage and moves it from its first position to its second position.
The anchor and tool assembly is used, for example, in drilling oil and gas wells and to install liners and other well components. It is connected to a work string which can be raised, lowered, and rotated as desired from the surface of the well. A liner or other well component is attached to the anchor assembly mandrel. The assembly then is lowered into the well through an existing conduit to position the anchor assembly at the desired depth. Once the anchor assembly is in position, the swage is moved axially over the mandrel outer surface by a setting assembly. More particularly, the swage is moved from a position proximate to the expandable metal sleeve to a position under the sleeve, thereby expanding the sleeve radially outward into contact with the existing conduit. Once the metal sleeve has been expanded, the tool is manipulated to release the running assembly from the anchor assembly, and the running and setting assemblies are retrieved from the conduit to complete installation of the liner or other well component.
For example,
Hanger 11 includes a hanger mandrel 20, a swage 21, and a metal sleeve 22. A liner 17 is attached to the lower end of tool 10, more specifically to hanger mandrel 20 of hanger 11. Liner 17 in turn is assembled from multiple lengths of tubular sections threaded together through connectors. In addition, liner 17 typically will have various other components as may be need to perform various operations in the well, both before and after setting hanger 11. For example, liner 17 typically will be cemented in place. Thus, tool 10 also will include, or the liner 17 will incorporate various well components used to perform such cementing operations, such as a slick joint, cement packoffs, plug landing collars, and the like (not shown). Operation of tool 10, as discussed in detail below, is accomplished in part by increasing hydraulic pressure within tool 10. Thus, when liner 17 is not cemented in place, tool 10 or liner 17 preferably incorporate some mechanism to allow pressure to be built up in work string 14, such as a seat (not shown) onto which a ball may be dropped. Importantly, liner 17 also may include a drill bit (not shown) so that the borehole may be drilled and extended as liner 17 and tool 10 are lowered through existing casing 15.
It will be appreciated, however, that in its broadest embodiments, the anchor and tool assemblies of the subject invention do not comprise any specific liner assemblies or a liner. The anchor assemblies may be used to install a variety of liner assemblies, and in general, may be used to install any other downhole tool or component that requires anchoring within a conduit, such as whipstocks, packers, bridge plugs, cement plugs, frac plugs, slotted pipe, and polished bore receptacles (PBRs). Similarly, while preferred liner hanger tool 10 is exemplified by showing a liner suspended in tension from the anchor assembly, the novel anchor assemblies may also be used to support liners or other well components extending above the anchor assembly, or to secure such components in resistance to torsional forces.
Moreover, as used in industry, a “casing” is generally considered to be a tubular conduit lining a well bore and extending from the surface of the well. Likewise, a “liner” is generally considered to be a tubular conduit that does not extend from the surface of the well, and instead is supported within an existing casing or another liner. In the context of the subject invention, however, it shall be understood that “casing” shall refer to any existing conduit in the well into which the anchor assembly will be installed, whether it extends to the surface or not, and “liner” shall refer to a conduit having an external diameter less than the internal diameter of the casing into which the anchor assembly is installed.
Even more broadly, it will be appreciated that the tool has been exemplified in the context of casings and liners used in drilling oil and gas wells. The invention, however, is not so limited in its application. The novel tool and anchor assemblies may be used advantageously in other conduits where it is necessary to install an anchor by working a tool through an existing conduit to install other tools or smaller conduits.
It also will be appreciated that the figures and description refer to tool 10 as being vertically oriented. Modern wells, however, often are not drilled vertically and, indeed, may extend horizontally through the earth. The novel tool and anchor assemblies also may be used in horizontal wells. Thus, references to up, down, upward, downward, above, below, upper, lower, and the like shall be understood as relative terms in that context.
In
Further details regarding liner hanger 11 may be seen in
As may be seen therefrom, hanger mandrel 20 is a generally cylindrical body providing a conduit. It provides a connection at its lower end to, e.g., a liner string (such as liner 17 shown in
As may be seen from
Swage 21 is supported for axial movement across the outer surface of mandrel 20. In the run-in position, it is proximate to expandable metal sleeve 22, i.e., it is generally axially removed from sleeve 22 and has not moved into a position to expand sleeve 22 into contact with an existing casing. In theory it may be spaced some distance therefrom, but preferably, as shown in
By comparing
Movement of swage 21 under sleeve 22 preferably is facilitated by tapering the lower end of swage 21 and the upper end of sleeve 22, as seen in
The outer surface of swage 21, or more precisely, that portion of the outer surface of swage 21 that will move under sleeve 22 preferably is polished smooth to reduce friction therebetween. Likewise, the inner surface of swage 21 preferably is smooth and polished to reduce friction with mandrel 20. Moreover, once hanger 11 is installed in an existing casing, the upper portion of swage 21 is able to provide a polished bore receptacle into which other well components may be installed.
Preferably, the novel anchor assemblies also include a ratchet mechanism that engages the mandrel and swage and resists reverse movement of the swage, that is, movement of the swage back toward its first position, in which it is axially proximate to the sleeve, and away from its second position, where it is under the sleeve. Liner hanger 11, for example, is provided with a ratchet ring 26 mounted between mandrel 20 and swage 21. Ratchet ring 26 has pawls that normally engage corresponding detents in annular recesses on, respectively, the outer surface of mandrel 20 and the inner surface of swage 21. Ratchet ring 26 is a split ring, allowing it to compress circumferentially, depressing the pawls and allowing them to pass under the detents on swage 21 as swage 21 travels downward in expanding sleeve 22. The pawls on ring 26 are forced into engagement with the detents, however, if there is any upward travel of swage 21. Thus, once set, relative movement between mandrel 20, swage 21, and sleeve 22 is resisted by ratchet ring 26 on the one hand and mandrel shoulder 23 on the other.
It will be appreciated from the foregoing that in the novel anchor assemblies, or at least in the area of travel by the swage, the effective outer diameter of the mandrel and the effective inner diameter of the swage are substantially equal, whereas the effective outer diameter of the swage is greater than the effective inner diameter of sleeve. Thus, for example and as may be seen in
By effective diameter it will be understood that reference is made to the profile of the part as viewed axially along the path of travel by swage 21. In other words, the effective diameter takes into account any protruding structures such as annular bosses which may project from the nominal surface of a part. Similarly, when projections such as annular bosses are provided on mandrel 20 or swage 21, the outer diameter of mandrel 20 will be slightly greater than the inner diameter of swage 21 so that a seal may be created therebetween. “Substantially equal” is intended to encompass such variations, and other normal tolerances in tools of this kind.
Moreover, since hanger mandrel 20 is in a sense the uppermost component of liner 17 to be installed, it will be appreciated that its inner diameter preferably is at least as great as the inner diameter of liner 17 which will be installed. Thus, any further constriction of the conduit being installed in the well will be avoided. More preferably, however, it is substantially equal to the inner diameter of liner 17 so that mandrel 20 may be made as thick as possible.
It also will be appreciated that the mandrel of the novel anchor assemblies is substantially nondeformable, i.e., it resists significant deformation when the swage is moved over its outer surface to expand the metal sleeve. Thus, expansion of the sleeve is facilitated and the mandrel is able to provide significant radial support for the expanded sleeve. It is expected that some compression may be tolerable, on the order of a percent or so, but generally compression is kept to a minimum to maximize the amount of radial support provided. Thus, the mandrel of the novel anchors preferably is fabricated from relatively hard ferrous and non-ferrous metal alloys and, most preferably, from such metal alloys that are corrosion resistant. Suitable ferrous alloys include nickel-chromium-molybdenum steel and other high yield steel. Non-ferrous alloys include nickel, iron, or cobalt superalloys, such as Inconel, Hastelloy, Waspaloy, Rene, and Monel alloys. The superalloys are corrosion resistant, that is, they are more resistant to the chemical, thermal, pressure, and other corrosive conditions commonly encountered in oil and gas wells. Thus, superalloys or other corrosion resistant alloys may be preferable when corrosion of the anchor is a potential problem.
The swage of the novel anchors also is preferably fabricated from such materials. By using such high yield alloys, not only is expansion of the sleeve facilitated, but the mandrel and swage also are able to provide significant radial support for the expanded sleeve and the swage may be made more resistant to corrosion as well.
On the other hand, the sleeve of the novel anchor assemblies preferably is fabricated from ductile metal, such as ductile ferrous and non-ferrous metal alloys. The alloys should be sufficiently ductile to allow expansion of the sleeve without creating cracks therein. Examples of such alloys include ductile aluminum, brass, bronze, stainless steel, and carbon steel. Preferably, the metal has an elongation factor of approximately 3 to 4 times the anticipated expansion of the sleeve. For example, if the sleeve is required to expand on the order of 3%, it will be fabricated from a metal having an elongation factor of from about 9 to about 12%. In general, therefore, the material used to fabricate the sleeve should have an elongation factor of at least 10%, preferably from about 10 to about 20%. At the same time, however, the sleeve should not be fabricated from material that is so ductile that it cannot retain its grip on an existing casing.
It also will be appreciated that the choice of materials for the mandrel, swage, and sleeve should be coordinated to provide minimal deformation of the mandrel, while allowing the swage to expand the sleeve without creating cracks therein. As higher yield materials are used in the mandrel and swage, it is possible to use progressively less ductile materials in the sleeve. Less ductile materials may provide the sleeve with greater gripping ability, but of course will require greater expansion forces.
Significantly, however, by using a ductile, expandable metal seal, and a nondeformable mandrel, it is possible to provide a strong, reliable seal with an existing casing, while avoiding the complexities of other mechanical hangers and the significant disadvantages of expandable liners. More specifically, the novel hangers do not have a weakened area such as exists at the junction of expanded and unexpanded portions of expandable liners. Thus, other factors being equal, the novel hangers are able to achieve higher load ratings.
In addition, expandable liners must be made relatively thick in part to compensate for the weakened area created between the expanded and unexpanded portions. The expandable sleeves of the novel hangers, however, are much thinner. Thus, other factors being equal, the expandable sleeves may be expanded, more easily, which in turn reduces the amount of force that must be generated by the setting assembly.
Ductile alloys, from which both conventional expandable liners and the expandable sleeves of the novel hangers may be made, once expanded, can relax and cause a reduction in the radial force applied to an existing casing. Conventional tools have provided support for expanded liner portions by leaving the swage or other expanding member in the well. The nondeformable mandrel of the novel liner hangers, however, has substantially the same outer diameter as the internal diameter of the swage. Thus, both the mandrel and the swage are able to provide radial support for the expanded sleeve. Other factors being equal, that increased radial support reduces “relaxation” of the expanded, relatively ductile sleeve and, in turn, tends to increase the load capacity of the anchor. At the same time, the mandrel is quite easily provided with an internal diameter at least as great as the liner which will be installed, thus avoiding any further constriction of the conduit provided through the well.
Expandable liner hangers, since they necessarily are fabricated from ductile alloys which in general are less resistant to corrosion, are more susceptible to corrosion and may not be used, or must be used with the expectation of a shorter service life in corrosive environments. The mandrel of the novel hangers, however, may be made of high yield alloys that are much more resistant to corrosion. The expandable sleeve of the novel hangers are fabricated from ductile, less corrosion resistant alloys, but it will be appreciated that as compared to a liner, only a relatively small surface area of the sleeve will be exposed to corrosive fluids. The length of the seal formed by the sleeve also is much greater than the thickness of a liner, expanded or otherwise. Thus, the novel hangers may be expected to have longer service lives in corrosive environments.
The expandable sleeve of the novel anchor assemblies also preferably is provided with various sealing and gripping elements to enhance the seal between the expanded sleeve and an existing casing and to increase the load capacity of the novel hangers. For example, as may be seen in
As noted above, the novel anchor assemblies are intended to be used in combination with a tool for installing the anchor in a tubular conduit. For example, running tool 12 is used to releasably engage hanger 11 and setting tool 13 is used to actuate swage 21 and set sleeve 22. There are a variety of mechanisms which may be incorporated into tools to provide such releasable engagement and actuation. In this respect, however, the subject invention does not encompass any specific tool or mechanism for releasably engaging, actuating, or otherwise installing the novel anchor assemblies. Preferably, however, the novel anchors are used with the tools disclosed herein. Those tools are capable of installing the novel anchors easily and reliably. Moreover, as now will be discussed in further detail, they incorporate various novel features and represent other embodiments of the subject invention.
Running tool 12 and setting tool 13, as will be appreciated by comparing
Tool mandrel 30 is connected at its upper end to a work string 14 (see
Tool mandrel 30 is a generally cylindrical body. Preferably, as illustrated, it comprises a plurality of tubular sections 31 to facilitate assembly of tool 10 as a whole. Tubular sections 31 may be joined by conventional threaded connectors. Preferably, however, the sections 31 of tool mandrel 30 are connected by novel clutch mechanisms of the subject invention.
The novel clutch mechanisms comprise shaft sections having threads on the ends to be joined. The shaft sections have prismatic outer surfaces adjacent to their threaded ends. A threaded connector joins the threaded ends of the shaft sections. The connector has axial splines. A pair of clutch collars is slidably supported on the prismatic outer surfaces of the shaft sections. The clutch collars have prismatic inner surfaces that engage the prismatic outer surfaces of the shaft sections and axial splines that engage the axial splines on the threaded connector. Preferably, the novel clutch mechanisms also comprise recesses adjacent to the mating prismatic surfaces that allow limited rotation of the clutch collars on the prismatic shaft sections to facilitate engagement and disengagement of the mating prismatic surfaces.
Accordingly, mandrel 30 of tool 10 includes a preferred embodiment 32 of the novel clutch mechanisms. More particularly, mandrel 30 is made up of a number of tubular sections 31 joined by novel connector assemblies 32. Connector assemblies 32 include threaded connectors 33 and clutch collars 34.
Tubular sections 31 have prismatic outer surfaces 35 adjacent to their threaded ends. That is, the normally cylindrical outer surfaces of tubular sections 31 have been cut to provide a plurality of flat surfaces extending axially along the tubular section such that, when viewed in cross section, flat surfaces define or can be extended to define a polygon. For example, as seen best in
It will be appreciated, therefore, that the novel clutch mechanisms provide for reliable and effective transmission of torque in both directions through a sectioned conduit, such as tool mandrel 30. In comparison to conventional set screws and the like, mating prismatic surfaces and splines on the connector and collars provide much greater surface area through which right-handed torque is transmitted. Thus, much greater rotational forces, and forces well in excess of the torque limit of the threaded connection, may be transmitted in a clockwise direction through a sectioned conduit and its connector assemblies without risking damage to threaded connections. The novel clutch mechanisms, therefore, are particularly suited for tools used in drilling in a liner and other applications that subject the tool to high torque. In addition, because the collars cannot rotate in a counterclockwise direction, or if recesses are provided can rotate in a counterclockwise direction only to a limited degree, left-handed torque may be applied to a tool mandrel without risk of significant loosening or of unthreading the connection. Thus, the tool may be designed to utilize reverse rotation, such as may be required for setting or release of a liner or other well component, without risking disassembly of the tool in a well bore.
At the same time, however, it will be appreciated that mandrel 30 may be made up with conventional connections. Moreover, the novel liner hangers may be used with tools having a conventional mandrel, and thus, the novel clutch mechanisms form no part of that aspect of the subject invention. It also will be appreciated that the novel clutch mechanisms may be used to advantage in making up any tubular strings, in mandrels for other tools, or in other sectioned conduits or shafts, or any other threaded connection where threads must be protected from excessive torque.
Running tool 12 includes a collet mechanism that releasably engages hanger mandrel 20 and which primarily bears the weight of liner 17 or other well components connected directly or indirectly to hanger mandrel 20. Running tool 12 also includes a releasable torque transfer mechanism for transferring torque to hanger mandrel 20 and a releasable dog mechanism that provides a connection between running tool 12 and tool mandrel 30.
Tubular section 31g of mandrel 30 provides a base structure on which the various other components of running tool 12 are assembled. As will be appreciated from the discussion follows, most of those other components are slidably supported, directly or indirectly, on tubular section 31g. During assembly of tool 10 and to a certain extent in their run-in position, however, they are fixed axially in place on tubular section 31g by the dog mechanism, which can be released to allow release of the collet mechanism engaging hanger mandrel 20.
More particularly, as seen best in
As may be seen best in
As may be appreciated from
Although not shown in their entirety or in great detail, it will be appreciated that dog housing 47 and tubular section 31g of mandrel 30 have cooperating recesses that entrap a plurality of dogs 48 as is common in the art. Those recesses allow dogs 48 to move radially, that is, in and out to a limited degree. It will be appreciated that the inner ends (in this sense, the bottom) of dogs 48 are provided with pawls which engage the recess in tubular section 31g. The annular surfaces of those pawls and recesses are coordinated such that downward movement of mandrel 30 relative to dog housing 47, for reasons to be discussed below, urges dogs 48 outward. In the run-in position, as shown in
Thus, dogs 48 are able to provide a translational engagement between mandrel 30 and running tool 12 when tool 10 is in the run-in position. This engagement is not typically loaded with large amounts of force when the tool is in its run-in position, as the weight of tool 10 and liner 17 is transmitted to tool mandrel 30 primarily through collet ends 41 and bottom collar 41 and torque is transmitted from mandrel 30 through thrust cap 45 and hanger mandrel 20. The engagement provided by dogs 48, however, facilitates assembly of tool 10 and will bear any compressive load inadvertently applied between hanger 11 and tool mandrel 30. Thus, dogs 48 will prevent liner hanger 11 and running tool 12 from moving upward on mandrel 30 such as might otherwise occur if tool 10 gets hung up as it is run into an existing casing. Release of dogs 48 from that engagement will be described in further detail below in the context of setting hanger 11 and release of running tool 12.
It will be appreciated that running tool 12 described above provides a reliable, effective mechanism for releasably engaging liner hanger 11, for securing liner hanger from moving axially on mandrel 30, and for transmitting torque from mandrel 30 to hanger mandrel 20. Thus, it is a preferred tool for use with the liner hangers of the subject invention. At the same time, however, other conventional running mechanisms, such as mechanisms utilizing a left-handed threaded nut or dogs only, may be used, particularly if it is not necessary or desirable to provide for the transmission of torque through the running mechanism. The subject invention is in no way limited to a specific running tool.
Setting tool 13 includes a hydraulic mechanism for generating translational force, relative to the tool mandrel and the work string to which it is connected, and a mechanism for transmitting that force to swage 21 which, upon actuation, expands metal sleeve 22 and sets hanger 11. It is connected to running tool 12 through their common tool mandrel 30, with tubular sections 31a-f of mandrel 30 providing a base structure on which the various other components of setting tool 13 are assembled.
As will be appreciated from
As is common in such actuators, they comprise a mandrel. Though actuators for other applications may employ different configurations, the mandrel in the novel actuators, as is typical for oil well tools and components, preferably is a generally cylindrical mandrel. A stationary sealing member, such as a piston, seal, or an extension of the mandrel itself, extends continuously around the exterior of the mandrel. A hydraulic barrel or cylinder is slidably supported on the outer surfaces of the mandrel and the stationary sealing member. The cylinder includes a sleeve or other body member with a pair of dynamic sealing members, such as pistons, seals, or extensions of the body member itself, spaced on either side of the stationary sealing member and slidably supporting the cylinder. The stationary sealing member divides the interior of the cylinder into two hydraulic chambers, a top chamber and a bottom chamber. An inlet port provides fluid communication into the bottom hydraulic chamber. An outlet port provides fluid communication into the top hydraulic chamber. Thus, when fluid is introduced into the bottom chamber, relative linear movement is created between the mandrel and the cylinder. In setting tool 13, this is downward movement of the cylinder relative to mandrel 30.
For example, what may be viewed as the lowermost hydraulic actuator 60e is shown in
In the run-in position shown in
Floating piston 61e, on the other hand, is distant from stationary piston 63e, and a top hydraulic chamber 66e is defined therebetween. One or more outlet ports 67e are provided in floating piston 61e to provide fluid communication between top hydraulic chamber 66e and the exterior of cylinder sleeve 62e. Alternately, outlet ports could be provided in cylinder sleeve 62e, and it will be appreciated that the exterior of cylinder sleeve 62e is in fluid communication with the exterior of the tool, i.e., the well bore, via clearances between cylinder sleeve 62e and swage 21. Thus, fluid flowing through inlet ports 65e into bottom hydraulic chamber 64e will urge floating piston 61f downward, and in turn cause fluid to flow out of top hydraulic chamber 66e through outlet ports 67e and allow actuator 60e to travel downward along mandrel 30, as may be seen in
Setting tool 13 includes another actuator 60d of similar construction located above actuator 60e just described. Parts of actuator 60d are shown in
Setting tool 13 engages swage 21 of liner hanger 11 via another hydraulic actuator 60c which is located above hydraulic actuator 60d. More particularly, as may be seen in
It will be noted that the upper portion of sleeve 62c extends above swage 21 while its lower portion extends through swage 21, and that upper end of sleeve 62c is enlarged relative to its lower portion. An annular adjusting collar 68 is connected to the reduced diameter portion of sleeve 62c via, e.g., threaded connections. An annular stop collar 69 is slidably carried on the reduced diameter portion of sleeve 62c spaced somewhat below adjusting collar 68 and just above and abutting swage 21. Adjusting collar 68 and stop collar 69 are tied together by shear pins (not shown) or other shearable members. It will be appreciated that in assembling tool 10, rotation of adjusting collar 68 and stop collar 69 allows relative movement between setting tool 13 and running tool 12 on the one hand and liner hanger 11 on the other, ultimately allowing collet ends 41 of running tool 12 to be aligned in annular recesses 29 of hanger mandrel 20.
Setting tool 13 includes what may be viewed as additional drive actuators 60a and 60b located above engagement actuator 60c shown in
It will be appreciated that hydraulic actuators 60 preferably are immobilized in their run-in position. Otherwise, they may be actuated to a greater or lesser degree by differences in hydrostatic pressure between the interior of mandrel 30 and the exterior of tool 10. Thus, setting tool 13 preferably incorporates shearable members, such as pins, screws, and the like, or other means of releasably fixing actuators 60 to mandrel 30.
In accordance with another aspect of the subject invention, the hydraulic actuators also may include a balance piston. The balance piston is slidably supported within the top hydraulic chamber of the actuator, preferably on the mandrel. The balance piston includes a passageway extending axially through the balance piston. Fluid communication through the piston and between its upper and lower sides is controlled by a normally shut valve in the passageway. Thus, in the absence of relative movement between the mandrel and the cylinder, the balance piston is able to slide in response to a difference in hydrostatic pressure between the outlet port, which is on one side of the balance piston, and the portion of the top hydraulic chamber that is on the bottom side of the balance piston.
For example, as may be seen in
Balance piston 70a has a passageway 72a extending axially through its body portion, i.e., from its upper side to its lower side. Passageway 72a is thus capable of providing fluid communication through balance piston 70a, that is, between hydraulic chamber 71a and the rest of top hydraulic chamber 66a. Fluid communication through passageway 72a, however, is controlled by a normally shut valve, such as rupturable diaphragm 73a. When diaphragm 73a is in its closed, or unruptured state, fluid is unable to flow between hydraulic chamber 71a and the rest of top hydraulic chamber 66a.
Actuator 60b also includes a balance piston 70b identical to balance piston 70a described above. Thus, when tool 10 is in its run-in position shown in
Moreover, by not allowing ingress of significant quantities of fluid from a well bore as tool 10 is being run into a well, balance pistons 70a and 70b further enhance the reliability of actuators 60a and 60b. That is, balance pistons 70a and 70b greatly reduce the amount of debris that can enter top hydraulic chambers 66a and 66b, and since they are located in close proximity to outlet ports 67a and 67b, the substantial majority of the travel path is maintained free and clear of debris. Hydraulic chambers 66a and 66b preferably are filled with clean hydraulic fluid during assembly of tool 10, thus further assuring that when actuated, floating pistons 61a and 61b and sleeves 62a and 62b will slide cleanly and smoothly over, respectively, tubular sections 31a and 31b and stationary pistons 63a and 63b.
It will be appreciated that for purposes of balancing the hydrostatic pressure between the top hydraulic chamber and a well bore the exact location of the balance piston in the top hydraulic chamber of the novel actuators is not critical. It may be spaced relatively close to a stationary piston and still provide such balancing. In practice, the balance piston will not have to travel a great distance to balance pressures and, therefore, it may be situated initially at almost any location in the top hydraulic chamber between the external opening of the outlet port and the stationary piston.
Preferably, however, the balance piston in the novel actuators is mounted as close to the external opening of the outlet port as practical so as to minimize exposure of the inside of the actuator to debris from a well bore. It may be mounted within a passageway in what might be termed the “port,” such as ports 67a shown in the illustrated embodiment 60a, or within what might otherwise be termed the “chamber,’ such as top hydraulic chamber 66a shown in the illustrated embodiment 60a. As understood in the subject invention, therefore, when referencing the location of a balance piston, the top hydraulic chamber may be understood as including all fluid cavities, chambers, passageways and the like between the port exit and the stationary piston. If mounted in a relatively narrow passageway, such as the outlet ports 67a, however, the balance piston will have to travel greater distances to balance hydrostatic pressures. Thus, in the illustrated embodiment 60a the balance piston 70a is mounted on tubular sections 31a in the relatively larger top hydraulic chamber 66a.
It also will be appreciated that, to provide the most effective protection from debris, the normally shut valves in the balance position should be selected such that they preferably are not opened to any significant degree by the pressure differentials they are expected to encounter prior to actuation of the actuator. At the same time, as will be appreciated from the discussion that follows, they must open, that is, provide release of increasing hydrostatic pressure in the top hydraulic chamber when the actuator is actuated. Most preferably, the normally shut valves remain open once initially opened. Thus, rupturable diaphragms are preferably employed because they provide reliable, predictable release of pressure, yet are simple in construction and can be installed easily. Other normally shut valve devices, such as check valves, pressure relief valves, and plugs with shearable threads, however, may be used in the balance piston on the novel actuators.
The setting assemblies of the subject invention also preferably include some means for indicating whether the swage has been fully stroked into position under the expandable metal sleeve. Thus, as shown in
It will be appreciated that setting tool 13 described above provides a reliable, effective mechanism for actuating swage 21, and it incorporates novel hydraulic actuators providing significant advantages over the prior art. Thus, it is a preferred tool for use with the anchor assemblies of the subject invention. At the same time, however, there are a variety of hydraulic and other types of mechanisms which are commonly used in downhole tools to generate linear force and motion, such as hydraulic jack mechanisms and mechanisms actuated by explosive charges or by releasing weight on, pushing, pulling, or rotating the work string. In general, such mechanism may be adapted for use with the novel anchor assemblies, and it is not necessary to use any particular setting tool or mechanism to set the novel anchor assemblies.
Moreover, it will be appreciated that the novel setting assemblies, because they include hydraulic actuators having a balance piston, are able to balance hydraulic pressures that otherwise might damage the actuator and are able to keep the actuator clear of debris that could interfere with its operation. Such improvements are desirable not only in setting the anchor assemblies of the subject invention, but also in the operation of other downhole tools and components where hydraulic actuators or other means of generating linear force are required. Accordingly, the subject invention in this aspect is not limited to use of the novel setting assemblies to actuate a particular anchor assembly or any other downhole tool or component.
The description of running tool 12 and setting tool 13 thus far has focused primarily on the configuration of those tools in their run-in position. When in its run-in position, tool 10 tool may be lowered into an existing casing, with our without rotation. If a liner is being installed, however, a drill bit preferably is attached to the end of the liner, as noted above, so that the liner may be drilled in. It also will be appreciated that tool mandrel 30 provides a conduit for circulation of fluids as may be needed for drilling or other operations in the well. Once tool 10 has been positioned at the desired depth, the liner hanger 11 will be set and released, and running tool 12 and setting tool 13 will be retrieved from the well, as now will be described in greater detail.
In general, liner hanger 11 is set by increasing the fluid pressure within mandrel 30. Increased fluid pressure actuates setting tool 13, which urges swage 21 downward and under expandable sleeve 22. At the same time, increasing fluid pressure in mandrel 30 causes a partial release of running tool 12 from mandrel 30. Once tool 10 is in this set position, running tool 12 may be released from liner hanger 11 by releasing weight on mandrel 30 through work string 14. Alternately, in the event that release does not occur, running tool 12 may be released from liner hanger 11 by rotating mandrel 30 a quarter-turn counterclockwise prior to releasing weight.
More particularly, once tool 10 has been run in to the desired depth, liner 17 may be cemented in place. The cementing operation will allow fluid pressure to be built up within work string 14 and mandrel 30. If a cementing operation will not first be performed, for whatever reason, it will be appreciated that other means will be provided, such as a ball seat, for allowing pressure to be built up.
As fluid pressure in mandrel 30 is increased to set tool 10, fluid enters bottom hydraulic chambers 64 of actuators 60 through inlet ports 65. The increasing fluid pressure in bottom hydraulic chambers 64 urges floating pistons 61b through 61f downward. Because floating pistons 61 and sleeves 62 are all interconnected, that force is transmitted throughout all actuators 60, and whatever shear members have been employed to immobilize actuators 60 are sheared, allowing actuators 60 to begin moving downward. That downward movement in turn causes an increase in pressure in top hydraulic chambers 66 which eventually ruptures diaphragms 73, allowing fluid to flow through balance pistons 70. Continuing flow of fluid into bottom hydraulic chambers 64 causes further downward travel of actuators 60. Since fluid communication has been established in passageways 72, balance pistons 70 are urged downward along mandrel 30 with floating pistons 61, as may be seen by comparing
As actuators 60 continue traveling downward along mandrel 30, as best seen by comparing
Finally, as noted above, the increasing fluid pressure within mandrel 30 not only causes setting of liner hanger 11, but also causes a partial release of running tool 12 from mandrel 30. More specifically, as understood best by comparing
That movement of locking piston 50 uncovers recesses in dog housing 47. As discussed above, dogs 48 are able to move radially (to a limited degree) within those recesses. Once uncovered, however, dogs 48 will be urged outward and out of engagement with tubular section 31g if mandrel 30 is moved downward. Thus, running tool 12 is partially released from mandrel 30 in the sense that mandrel 30, though restricted from relative upward movement, is now able to move downward relative to running tool 12. Other mechanisms for setting and releasing dogs, such as those including one or a combination of mechanical or hydraulic mechanisms, are known, however, and may be used in running tool 12.
Once liner hanger 11 has been set and any other desired operations are completed, running and setting tools 12 and 13 are retrieved from the well by first moving tool 10 to a “release” position.
As best seen by comparing
Finally, as best seen by comparing
In the event running tool 12 is not released from mandrel 30 as tool 10 is set, it will be appreciated that it may be released by rotating mandrel 30 a quarter-turn counterclockwise and then releasing weight on mandrel 30. That is, left-handed “J” slots (not shown) are provided in tubular section 31g. Such “J” slots are well known in the art and provide an alternate method of releasing running tool 12 from hanger mandrel 20. More specifically, dogs 48 may enter lateral portions of the “J” slots by rotating mandrel 30 a quarter-turn counterclockwise. Upon reaching axial portions of the slots, weight may be released onto mandrel 30 to move it downward relative to running tool 12. That downward movement will re-engage running tool 12 and remove radial support for collet ends 41 as described above. Preferably, shear wires or other shear members are provided to provide a certain amount of resistance to such counterclockwise rotation in order to minimize the risk of inadvertent release.
While this invention has been disclosed and discussed primarily in terms of specific embodiments thereof, it is not intended to be limited thereto. Other modifications and embodiments will be apparent to the worker in the art.
This nonprovisional application claims priority of prior provisional application of Michael J. Harris and Marty Stulberg, entitled “Anchoring Device,” U.S. Ser. No. 61/166,169, filed Apr. 2, 2009.
| Number | Date | Country | |
|---|---|---|---|
| 61166169 | Apr 2009 | US |
