Self-translating winch and automatic lubricator for well-based potential energy conversion systems

Abstract

A self-translating winch includes a frame providing one or more support surfaces, a grooved drum coupled to a first end of a line and operable to spool the line thereon, and a back-drivable linear guide mounting the drum to the frame between the one or more support surfaces. The self-translating winch further includes a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line, as well as a winch motor mated with the grooved drum and operable to provide torque for spooling the line thereon. The second end of the line is attached to a load to be raised or lowered by the self-translating winch.

Description

Atty. Docket No.: 081088-000030SELF-TRANSLATING WINCH AND AUTOMATIC LUBRICATOR FOR WELLBASED POTENTIAL ENERGY CONVERSION SYSTEMSFIELD

[0001] The present disclosure relates to potential energy conversion systems and, more particularly, to systems and apparatuses for automatic translating and lubrication of components in potential energy conversion systems, and potential energy conversion methods related thereto.BACKGROUND

[0002] According to the U.S. Energy' Information Administration, in 2019, the total energy' generation from wind and solar resources was a collective 8% of all energy generated. Due to the intermittent nature of wind and solar power generation, these sources are unreliable for consistent power generation. By themselves, these power sources are unable to produce electricity7in lockstep with demand, unlike other energy sources such as natural gas, nuclear, or coal power, which have fewer condition-based operational constraints. As a result, there has been growing demand for energy storage technologies to harness renewable and other intermittent energy sources in times of excess production capacity and release the stored energy when there is excess demand or when production capacity' is low.

[0003] Batteries and supercapacitors are increasingly being used for storage of excess energy'. However, these technologies may be expensive, particularly when employed for storage of massive amounts of electricity.

[0004] Gravity-based potential energy' storage is also a feasible approach for addressing intermittent power generation. In such potential energy' storage systems, a mass is suspended and electrical power is input to mechanically elevate the mass to a higher elevation when excess power is available. The stored potential energy’ is then converted back to electricity in response to demand by lowering the mass and driving a mechanical generator. Using modem winches and generators, gravity-based systems can achieve high storage efficiency, with losses often below about 20%. However, winching systems utilized in gravity-based potential energy’ storage systems may include sheaves for wire rope alignment, as well as large platforms for housing both the sheave and the winch. These large platforms may increase a footprint of the gravitybased potential energy storage systems and reduce their practicality in urban environments and other areas where space is constrained. Similarly, the use of a sheave may increase the bending frequency of the wire rope, leading to increased wire rope wear and a shorter lifetime for the system. Further, during operation of gravity -based potential energy storage systems, a failure toAtty. Docket No.: 081088-000030 maintain constant lubrication on any wire rope utilized in the raising and lowering of the mass may lead to premature failure or inefficiency.SUMMARY

[0005] The present disclosure generally relates to systems and apparatuses for automatic translating and lubrication of components in potential energy conversion systems.

[0006] In some aspects, potential energy conversion systems include a movable mass suspended by a line in a non-producing well and a self-translating winch mounted to a winch platform over the non-producing well. The self-translating winch includes a drum coupled to the line and operable to spool the line thereon, a back-drivable linear guide mounting the drum to the winch platform, and a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line. The potential energy conversion system further comprises a motor coupled to the selftranslating winch and operable to spool the line on the drum of the self-translating winch.

[0007] In further aspects, methods of spooling a line include mounting a drum of a winch to a back-drivable linear guide provided on a frame of the winch, mating the drum with a passive lateral translation mechanism provided on the frame of the winch, where the passive lateral translation mechanism is operable to translate the drum along the back-drivable linear guide, and mating a first end of the line to the drum, wherein a second end of the line is mated to a load to be raised and lowered by the winch. The methods may further include rotating the winch via a winch motor to spool the line onto the drum and raise the load, translating the drum along the back-drivable linear guide in response to a lateral component of tension in the line during spooling, and receiving the line on the drum with a fleet angle less than or equal to about 10via the passive lateral translation mechanism.

[0008] In additional aspects, self-translating winches include a frame providing one or more support surfaces, a grooved drum coupled to a first end of a line and operable to spool the line thereon, and a back-drivable linear guide mounting the drum to the frame between the one or more support surfaces. The self-translating winch further includes a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line, as well as a winch motor mated with the grooved drum and operable to provide torque for spooling the line thereon. The second end of the line is attached to a load to be raised or lowered by the self-translating winch.Atty'. Docket No.: 081088-000030BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following figures are included to illustrate certain aspects of the present disclosure and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to one having ordinary skill in the art and having the benefit of this disclosure.

[0010] FIG. 1 is a schematic of a potential energy' conversion system housed in a nonproducing well in accordance with the present disclosure.

[0011] FIG. 2 is a schematic of a potential energy' conversion system housed in a nonproducing well 102 and omitting a sheave pulley in accordance with the present disclosure.

[0012] FIG. 3 is a schematic top view of a self-translating winch in accordance with the present disclosure.

[0013] FIG. 4 is a schematic view of a compact self-translating winch in accordance with the present disclosure.

[0014] FIG. 5 is a schematic view of a chain-drive self-translating winch in accordance with the present disclosure.

[0015] FIG. 6 is a schematic top view of a smart self-translating winch in accordance with the present disclosure.

[0016] FIG. 7 is a schematic top view of a track-based self-translating winch in accordance with the present disclosure.

[0017] FIG. 8 is a schematic top view of a floating self-translating winch in accordance with the present disclosure.

[0018] FIG. 9 is a schematic side view of a labyrinthine self-translating winch in accordance with the present disclosure.

[0019] FIG. 10 is a schematic top view of a rectilinear labyrinth that may' be present in a labyrinthine self-translating winch in accordance with the present disclosure.

[0020] FIG. 11 is a schematic side view of a solar self-translating winch in accordance with the present disclosure.

[0021] FIG. 12 is a schematic of an auto-lubricating potential energy' conversion system housed in a non-producing well in accordance with the present disclosure.Atty. Docket No.: 081088-000030

[0022] FIG. 13 is a schematic of an auto-lubricating cover within a potential energy’ conversion system positioned above a non-producing well in accordance with the present disclosure.

[0023] FIG. 14 is an illustration of a rotationally powered auto-lubricating cover within a potential energy’ conversion system positioned above a non-producing well in accordance with the present disclosure.DETAILED DESCRIPTION

[0024] The present disclosure relates to potential energy’ conversion systems and, more particularly, to systems and apparatuses for automatic translating and lubrication of components in potential energy conversion systems and potential energy conversion methods related thereto. As discussed above, there are limitations to conventional gravity -based potential energy storage approaches.

[0025] The present disclosure provides energy storage approaches that maintain the advantages of gravity-based potential energy storage of excess energy produced from other sources, such as solar and wind energy sources, while also overcoming the challenges of providing large elevation changes to facilitate utilization of smaller masses. Namely, the present disclosure provides potential energy conversion systems that utilize existing infrastructure in the form of inactive (idle) and / or abandoned wellbores that are no longer producing a natural resource (e.g, a hydrocarbon resource or water) to house a suspended mass, possibly within a cased interval thereof above a wellbore plug sealing a lower section of the wellbore, for purposes of storing and releasing potential energy’ as the movable mass travels up and down. Following drilling completions, wells may include a narrow casing extending thousands of feet into the earth (e.g. , a nine-inch diameter casing extending up to 15000 feet or even further into the earth). The large vertical distance may be exploited in the present disclosure for providing a substantial elevation change of a suspended mass in gravity -based potential energy conversion systems disclosed herein.

[0026] The suspended masses of these potential energy conversion systems may be suspended via a line that extends to the surface, where the line is mated to a winch. The winch may be operable to rotate and spool the line thereon while raising the suspended mass, while further operable to unspool the line to lower the suspended mass. However, a fleet angle (an angular offset between the line and the centerline of the drum) may control the compact spooling of the line during rotation of the drum, such that a larger fleet angle may lead to uneven winding,Atty. Docket No.: 081088-000030 increased wear, and possible line failure. As such, significant efforts have been made to reduce the fleet angle of winch drums through the use of additional sheaves, fleet-angle towers, and increased distances between the winch drum and any sheaves. These solutions, however, may significantly increase the footprint of the winch system, while further increasing cost and bending of the line.

[0027] Accordingly, the methods and systems of the present disclosure include passively translating winch drums mounted to back-drivable linear guides, such that the winch drum may spool the line at a near-zero fleet angle (e.g, less than or equal to about 1°) while omitting any additional sheaves or towers. The disclosed embodiments may provide reduced costs, reduced footprints, and increased lifespan for the line, while maintaining consistent spooling on the winch drum. In some embodiments of the present disclosure, actuators may be incorporated into these systems to provide active control of the translation of the winch drums, while maintaining back- drivability to ensure the line spools with the least resistance. In these embodiments, the disclosed systems and methods may further provide lower energy costs and control complexity than traditional, fully active translating systems, and may provide a graceful transition into a passive system after failure that retains similar spooling quality. The disclosed systems and methods may enable the retrofitting of traditional systems without changing the fairlead geometry7used to guide the line, such that existing systems may be provided with a reduced footprint and operational cost without a full workover. The disclosed methods and systems may be utilized in any application that includes a winch drum in a semi-permanent location (e.g., hoists, cranes, mooring systems, etc.), such that the application of the self-translating winch system is not limited to potential energy conversion systems.

[0028] Potential energy conversion systems housed in a non-producing well, as disclosed herein, may provide a number of advantages. One advantage is that the non-producing wells maybe converted to afford potential energy storage with little additional infrastructure investment. The main infrastructure investment with a well is already bome by the entity who drilled the well to produce a natural resource therefrom. Thus, the potential energy conversion systems disclosed herein may utilize this existing infrastructure (which may be nearly worthless or even a financial liability) to add new value thereto. Advantageously, utilizing an abandoned, nonproducing well may turn a nuisance asset into an environmentally friendly and socially positive energy- storage resource. According to Enverus, an online database that tracks oil and gas well information, there are about 1.380,000 inactive and unplugged wells across the United StatesAtty. Docket No.: 081088-000030 alone, making up about 40% of all wells. As such, there is a large inventory of non-producing wells available for conversion into potential energy storage systems according to the disclosure herein.

[0029] The potential energy conversion systems disclosed herein may be applicable to both cased and uncased wells, as well as those that are plugged or unplugged. Plugged wells may be desirable due to their lower release rate of methane and other greenhouse gases in comparison to unplugged wells (up to 5000 times less leakage). At the very least, incorporating a potential energy conversion system into an unplugged well may lessen the overall environmental impact of the well by counterbalancing a portion of the impact of the greenhouse gases released therefrom. Even more desirably, retrofitting an unplugged, non-producing well for potential energy storage according to the disclosure herein may provide an economic impetus (incentive) for plugging the well during installation of the potential energy conversion system. Thus, a further advantage of the potential energy conversion systems disclosed herein includes a dual benefit in the reduction of methane leakage with an associated positive environmental impact through an increase in "green" energy storage capacity.

[0030] In the disclosure herein, the terms “potential energy conversion’’ and “potential energy storage” may be used interchangeably depending on context. It is to be appreciated that these terms may reference the point in time at which a given system is operating, z.e., converting potential energy when lowering a movable mass and storing potential energy when raising a movable mass. Thus, even if a given system is referred to by the terms “potential energy conversion system” or “potential energy storage system,” it is to be recognized that these interchangeable terms reference a single system embodiment.

[0031] The terms “mass.” “movable mass,” and “suspended mass” may be used interchangeably herein.

[0032] Potential energy conversion systems of the present disclosure are gravity-based systems that operate by storing or releasing potential energy through vertical movement of a mass suspended within a well. The systems may convert electricity to potential energy as the mass is raised, and the potential energy may be converted back to electricity as the mass is lowered. In non-limiting examples, the mass may be raised in times of excess energy production, and electricity may be generated when energy production capacity is needed to support grid demand. The amount of potential energy storable by the potential energy' conversion systems, and the efficiency thereof, may be defined by a number of factors that include the depth andAtty. Docket No.: 081088-000030 width of the well: the weight of the suspended mass: the presence of deviations, inclinations, or doglegs within the well; and the properties of the contents within the well (if any), such as fluid viscosity, fluid density, pressure, and the like.

[0033] The potential energy' conversion systems may be incorporated within any well extending below the earth’s surface. While the potential energy conversion systems may be located within a well of any depth, the well depth may, more desirably, be about 5000 feet or more, or about 10000 feet or more, or about 15000 feet or more, or about 20000 feet or more, or about 25000 feet or more. Exemplary' ranges include depths within a range of about 5000 feet to about 25000 feet, or about 5000 feet to about 15000 feet, or about 1000 feet to about 10000 feet, or about 10000 feet to about 20000 feet. The mass may be located in a substantially vertical section of the well extending over these vertical distances, such as betw een a w ellhead at the earth’s surface and a plug located at a specified depth within the well. The plug may divide the well into upper and lower sections. The mass may move within the upper section of the wellbore, such as within a cased interval of the wellbore. The upper section of the wellbore may be filled with a fluid that is introduced into the wellbore to facilitate translation of the mass up and down.

[0034] In addition to vertical distance traveled, the weight of the suspended mass is another variable that determines the amount of potential energy' that may be stored by the systems. Systems in which the suspended mass travels over a larger vertical distance may utilize a suspended mass having a lower weight to achieve a given amount of potential energy storage, and those in which the suspended mass travels over a shorter distance may utilize a larger mass to provide a comparable amount of potential energy storage. Thus, for a potential energy storage system featuring a given vertical distance over which the suspended mass may travel, a mass of appropriate size may be chosen to provide a desired amount of potential energy storage (up to the failure point of a cable or similar line suspending the mass). As such, any size mass may be utilized without departing from the present disclosure. In non-limiting examples, the mass may weigh about 10 metric tons to about 300 metric tons. Practical considerations for the mass selection may include the w ell diameter and the carrying capacity of mechanical components of the systems (e. . support lines, winches, re-directs, and the like).

[0035] The physical size of the suspended mass in the wellbore may be determined by the w ellbore diameter, the density7of the material comprising the suspended mass, and the vertical distance over which the bottom of the suspended mass needs to move vertically to store or release a given amount of energy. The maximum amount of energy’ storable or releasable by / from theAtty. Docket No.: 081088-000030 potential energy’ conversion systems is determined by the relationship E = mgh, where E is the stored / released energy, m is the mass, g is the gravitational acceleration constant (e.g., 9.8 m / s2), and h is the maximum displacement (height) over which the suspended mass may move. Thus, the amount of energy' storable / releasable is determined by the mass suspended in a given well, given that the maximum displacement may be fixed in a given well based on the vertical distance the suspended mass may move. If the suspended mass is of insufficient size to store / release a given amount of energy and cannot be made "longer" (extend a larger vertical distance within the well), possible recourses are to increase the diameter of the mass by making the mass extend closer to the walls of the well (e.g., nearer the casing in a cased interval of the well) and / or increase the density of the material comprising the suspended mass.

[0036] The well in which the potential energy' conversion system is located may have substantially the same diameter in a substantially vertical upper section extending from the earth’s surface to a plug in the well or between the earth’s surface and the well bottom. Alternately, the well in which the potential energy conversion system is located may have anon- uniform diameter between the earth’s surface and a plug or the well bottoms. For example, in embodiments, the well may taper and / or undergo stepwise graduations from a larger diameter to a smaller diameter at the plug or the well bottoms. In non-limiting examples, the well may have a minimum diameter of about 4 inches, or about 6 inches, or about 8 inches, or about 10 inches, or about 12 inches at a narrowest location within the well, which may be present in a well having a uniform or non-uniform diameter. These distances may represent the distance between the subterranean formation upon opposite sides of an uncased well or between the surface of a casing upon opposite sides of a cased well. The movable mass need not necessarily be located in a minimum-diameter portion of a well having a non-uniform diameter. Instead, the movable mass may be sized to fit within the minimum diameter of the interval where the movable mass is located.

[0037] The diameter of the suspended mass may have a maximum diameter that is slightly less than the minimum diameter of the interval within which the mass moves. The space between the suspended mass and the walls of the well or the casing is referred to as the annulus. In nonlimiting embodiments, the annulus between the walls of the well or the casing and the suspended mass may be about 6 inches or less, or about 4 inches or less, or about 3 inches or less, or about 2 inches or less, or about 1 inch or less, or about 0.9 inches or less, or about 0.8 inches or less, or about 0.7 inches or less, or about 0.6 inches or less, or about 0.5 inches or less, or about 0.4Atty. Docket No.: 081088-000030 inches or less, or about 0.3 inches or less, or about 0.2 inches or less, or about 0. 1 inches or less. In various embodiments, the annulus between the suspended mass and the walls of the well or the casing may range from about 0.1 inches to about 1 inch, or about 1 inch to about 3 inches, or about 0.3 inches to about 0.8 inches, or about 0.2 inches to about 0.5 inches, or about 0.5 inches to about 1.0 inches. A given annulus size may be chosen to afford a size of the suspended mass sufficient to store or release a specified amount of energy.

[0038] The suspended mass may fill a substantial volume of the available volume within a well or an interval thereof (e.g. , the volume of the interval above a plug), such as about 20% or more of the well volume, or about 30% or more of the well volume, or about 40% or more of the well volume, or about 50% or more of the well volume, or about 60% or more of the well volume, or about 70% or more of the well volume, or about 80% or more of the well volume. A maximum volume occupied by the suspended mass may be dictated by the vertical distance over which the suspended mass needs to move when storing or releasing potential energy. In non-limiting embodiments, the maximum volume occupied by the suspended mass may be about 95% or less of the well volume, or about 90% or less of the well volume, or about 85% or less of the well volume, or about 80% or less of the w ell volume, or about 75% or less of the w ell volume, or about 70% or less of the well volume, or about 65% or less of the w ell volume, or about 60% or less of the well volume, or about 55% or less of the well volume, or about 50% or less of the well volume, or about 45% or less of the well volume, or about 40% or less of the well volume, or about 35% or less of the well volume, or about 30% or less of the well volume, or about 25% or less of the well volume, or about 20% or less of the well volume, or about 15% or less of the well volume, or about 10% or less of the well volume, or about 5% or less of the well volume.

[0039] The suspended mass may be elongated to fit effectively within the well and have a length of up to about 1000 feet, or up to about 2000 feet, or up to about 3000 feet, or up to about 4000 feet, or up to about 5000 feet, or up to about 6000 feet, or up to about 7000 feet, or up to about 8000 feet, or up to about 9000 feet, or up to about 10000 feet, or up to about 11000 feet, or up to about 12000 feet, or up to about 13000 feet, or up to about 14000 feet, or up to about 15000 feet, or up to about 16000 feet, or up to about 17000 feet, or up to about 18000 feet, or up to about 19000 feet, or up to about 20000 feet. To facilitate introduction to the well, the suspended mass may be inserted modularly in smaller sections into the well.

[0040] Potential energy conversion systems disclosed herein may be installed within a nonproducing well, typically after the well has finished its service lifetime for extracting a resourceAtty. Docket No.: 081088-000030 from a subterranean formation. The well may be uncased or cased (completed), and may be capped or uncapped. Uncapped wells may be capped during installation of the potential energy conversion systems disclosed herein, thereby addressing both potential energy storage and environmental releases from the uncapped well. In a first step, an uncapped hydrocarbon well may be selected, preferably a well completed with a production casing extending from the surface down to an oil-bearing formation. The well may include a cased interval and anon-cased interval. Completed wells typically include one or more intervals having perforations about the diameter of the casing to allow the ingress of hydrocarbons from a hydrocarbon-bearing rock (subterranean formation). During installation of the potential energy conversion systems, a plug may be inserted above the perforations, such as a cement plug, packer, or other zonal isolation equipment that closes off the cased interval from ingress of hydrocarbons and other connate fluids into a section of the w ellbore above the plug. A suitable plug may be chosen based upon the well conditions and regulatory requirements where the well is located. The well may be cleaned of hydrocarbons and left void, filled with an inert gas such as nitrogen or argon, or at least partially filled with a fluid. Fluids that may be installed in the well include, for example, aqueous fluids, including any cased- well -compatible aqueous fluids known in the art of wellbore drilling and production. The fluid may be water, optionally including one or more additives. Suitable additives may include those to minimize corrosion and / or modify various rheological properties. For example, a suitable fluid may include additives such as nanosodium silicate at a concentration in a parts-per-million range (ppm, e.g., up to about 100 ppm) to coat steel components of the potential energy conversion systems against corrosion, reduce friction between guide and steel, and to otherwise reduce overall drag as a suspended mass moves up and down. In another example, a fluid in the w ell may include high-density brines or chemicals to maintain hydrostatic pressure to minimize well casing damage and limit inadvertent ingress of hydrocarbons into the wellbore section where the suspended mass resides. In non-limiting examples, the fluid in the well may include one or more of biocides, anti-corrosion chemicals, and scale inhibitors to prevent damage to the potential energy- conversion systems during extended deployment in the well.

[0041] FIG. 1 is an illustration of a potential energy conversion system 100 housed in anon- producing w ell 102 in accordance with the present disclosure. A movable mass 104 is suspended in w ell 102 and travels within a cased interval of well 102 extending between the surface 108 and a plug 103 placed at some depth (e.g., thousands of feet) in well 102. Plug 103 may isolateAtty. Docket No.: 081088-000030 an upper section of well 102 from a lower section, with mass 104 being located in the upper section. Movable mass 104 may include any object of suitable weight dimensioned for emplacement and movement within well 102. In one example, movable mass 104 may be created from steel tubing that is filled with iron ore pellets and fluid to increase the weight and / or density7. Movable mass 104 may also include one or more dense metals (e.g, tantalum or tungsten) and / or high-density fillers, such as depleted uranium, cement, sand, and the like. Movable mass 104 is suspended by a line 106, such as, but not limited to, a cable, wire rope, chain, synthetic rope, or the like. Line 106 connects the movable mass 104 to an electric motor capable of raising and lowering the movable mass 104 during operation, such as winch 112. The connection between movable mass 104 and winch 112 may include one or more sheave pulleys 110 or similar mechanical components that re-direct the force on line 106 as needed. The suspension components, including support line 106, winch 112, and optional sheave pulleys 110, may' also incorporate a number of swivels or other protection devices in-line that prevent damage to support line 106, such as from twisting, binding, abrading, and the like.

[0042] Winch 112 may be a regenerative winch that can expend pow er by spooling up the line 106 to elevate the movable mass 104, and also generate electricity7when operated in reverse as the line 106 is extended to lower movable mass 104 downward under the influence of gravity7. Regenerative winches suitable for use in potential energy7conversion systems may supply electricity as needed (e.g, to the electrical grid), or may be configured to transfer electricity to another storage medium, such as a battery or supercapacitor.

[0043] Alternately, winch 112 may be a standard winch that operates to raise the movable mass 104, while a separate generator (not shown) is mechanically connected to movable mass 104 to generate electricity as movable mass 104 is lowered within well 102. Line 106 may be decoupled between winch 112 and a separate generator to provide raising or lowering capabilities as needed, or a second line 106 may be coupled to the separate generator. For example, a winch 112 and separate generator may be deployed such that the winch 112 drives a spool when elevating the mass 104 and the generator (not pictured) is driven when lowering the mass 104 through gears or other means of interfacing with the spool, such that each task can be performed separately and, if necessary, optimized for efficiency considerations of winching or power generation. It is also within the scope of this disclosure that multiple winches 112 may be used to control one or more movable masses 104, where at least one of the multiple winches 112 is a regenerative winch. Further, while system 100 is shown with sheave pulleys 110 and winchAtty. Docket No.: 081088-000030112, other suitable mechanical devices or electric motors may be used interchangeably, including the use of a hoist, crane, or other suitable lifting device.

[0044] The movable mass 104 may be centered in well 102 using a series of centralizers (not show n) along the length of the movable mass 104. Centralizers suitable for stabilizing movable mass 104 may be designed such that only incidental contact occurs as the movable mass 104 transits vertically within well 102. Centralizers may also serve to mitigate casing wear by providing a sacrificial surface (a softer material than the well walls, for example) and by minimizing friction through other methods such as the shape of the centralizer, and material selection for coefficients of friction with casing material or fluid in the wellbore. By reducing friction, centralizers may also improve energy efficiency and round-trip efficiency of movable mass 104, thereby mitigating energy loss by decreasing casing-to-weight surface friction, viscous drag, and resistive pressure force through shape and material selection. The diameter of the centralizers may vary depending on the application, and may be gauged to account for features within the well, such as overall diameter of the casing in well 102, bends and deviations within well 102, and other factors familiar to those in the art of emplacement of wellbore tools. Centralizers installed on movable mass 104 may be made from any suitable material for use in oil well centralizers, including ultrahigh molecular weight polyethylene, for example.

[0045] Accordingly, various embodiments of potential energy' conversion systems may comprise: a movable mass suspended by a line in a non-producing well, in which the line is coupled to a motor operable to lift the movable mass, and a generator operable to produce electricity7when lowering the movable mass (e.g., under the influence of gravity'). During operation, the potential energy conversion systems may store potential energy by raising the movable mass, or release potential energy and convert the potential energy’ to electricity by lowering the movable mass. The motor may be part of a winch operable to lift the movable mass, such as a regenerative winch.

[0046] Although potential energy conversion system 100 may include sheave pulley 110, excessive bending wear of line 106 may occur when sheave pulley 110 is present. The presence of a sheave pulley 110 may increase maintenance or repairs of potential energy conversion system 100 unless actions are taken to mitigate the excessive bending and wear. Accordingly, an apparatus for increased lubrication of line 106 to reduce wear on sheave pulley 110 or winch 112, an omission of sheave pulley 110. or a combination thereof may be desirable. Various solutions to address wear on line 106 wear are described in reference to FIGS. 2-12. The potentialAtty. Docket No.: 081088-000030 energy conversion systems in FIGS. 2-12 are similar to that depicted in FIG. 1 and may be better understood by reference thereto.

[0047] FIG. 2 is an illustration of a potential energy conversion system housed in a nonproducing well 102 and omitting a sheave pulley in accordance with the present disclosure. Potential energy conversion system 200 may omit a sheave pulleys (e.g.. sheave pulley 110 of FIG. 1), such that line 106 is received within winch platform 202. Winch platform 202 may be located over non-producing well 102, and line 106 may enter through aperture 204 vertically defined through winch platform 202. Winch platform 202 may house thereon self-translating winch 206, described further hereinafter, which may directly receive line 106 without force redirection.

[0048] Winch platform 202 may be similarly installed at surface 108. By omitting a sheave pulley, potential energy conversion system 200 may have a smaller above-ground footprint than does potential energy conversion system 100 of FIG. 1. Accordingly, potential energy conversion system 200 may be more readily utilized in urban environments and other locales with spatial limitations. Winch platform 202, or non-producing well 102. may further include a mechanical guide 208 installed therebetween. Mechanical guide 208 may include a funnel- shaped, or otherwise beveled or chamfered, interior for additional guidance of line 106. Inclusion of mechanical guide 208 may aid in centering of line 106 on self-translating winch 206 through initial centering of line 106 near winch platform 202. The interior of mechanical guide 208 may include a large radius of curvature, as an increased bend radius may increase the lifetime of line 106.

[0049] FIG. 3 is a schematic top view of self-translating winch 206 in accordance with the present disclosure. Self-translating winch 206 may be initially positioned at or near the center of winch platform 202, as shown. Self-translating winch 206 may include line 106 wrapped thereon and protruding through aperture 204 defined within winch platform 202. Self-translating winch 206 may be free to translate in each of the cardinal directions “N,” “S,” “E,” and “W,’’ such that any force applied to self-translating winch 206 by line 106 may cause a complementary motion from self-translating winch 206. Self-translating winch 206 may include frame 302 mounted on winch platform 202, which may include first arm 304a and second arm 304b. Self-translating winch 206 further includes a drum 306 interposed between first arm 304a and second arm 304b, and drum 306 may accordingly rotate within frame 302. In some embodiments, drum 306 may be a grooved drum with a plurality of grooves around an outer circumferential surface of drumAtty. Docket No.: 081088-000030306. In these embodiments, the plurality’ of grooves may be defined with a prescribed groove pitch to establish a desired lay of line 106 around drum 306. The groove pitch may roughly correspond to a diameter of line 106 in order to better capture line 106 during spooling (e.g., the groove pitch is within about + / - 10 percent of the diameter of line 106). In these embodiments, grooves may be tapered or split near each of first arm 304a and second arm 304b to provide smooth reversals of spooling direction and to prevent piling of line 106 at frame 302 during operation.

[0050] During operation of self-translating winch 206, drum 306 may rotate by a motor (not shown) in the raising, or “R,"’ direction to store energy. Conversely, drum 306 may rotate in the lowering, orL‘L,” direction as mass 104 drops and advances towards plug 103 (FIGS. 1-2). The combination of rotational and translational degrees of freedom provided by self-translating w inch 206 may facilitate efficient spooling of line 106 on drum 306 w ithout redirection of the forces by additional components. In some embodiments, drum 306 may be mounted to a back- drivable linear guide, which may enable lateral (e.g.. east to west) travel of drum 306 above winch platform 202 for efficient spooling of line 106 thereon. The back-drivable linear guide may enable passive self-translation of drum 306 under a lateral component of tension within line 106, such that a near-zero fleet angle (e.g., less than or equal to about 1°) is maintained for spooling onto drum 306.

[0051] Various aspects of the self-translating winch 206 are described further hereinafter in reference to FIGS. 4-11, which may be better understood by further reference to FIGS. 2 and 3.

[0052] FIG. 4 is a schematic view of a compact self-translating winch 400 in accordance with some embodiments of the present disclosure. Compact self-translating winch 400 may be provided above well 102 (not shown) and may receive line 106 on drum 306 for spooling while raising a suspended mass. As discussed above, in some embodiments, drum 306 may include a plurality of grooves defined on its exterior circumferential surface to capture line 106 therein and encourage a desired lay of line 106. Compact self-translating w inch 400 may include a drum support 402 for retaining drum 306 thereon while enabling lateral translation during spooling and unspooling. Drum support 402 may be mounted along a drive belt 404 operable to act as a passive lateral translation mechanism for drum 306. In some embodiments, drive belt 404 may include a chain, a belt, a cable, or any other flexible component along which drum 306 may translate. To facilitate translation of drum 306 and drive belt 404, compact self-translating winch 400 may further include a plurality’ of drive sheaves 406 on opposite, lateral ends of drum 306Atty. Docket No.: 081088-000030 and mounted to frame 302. Drive belt 404 may be received within corresponding grooves of each of drive sheaves 406 to retain drive belt 404 therebetween, while further enabling smooth, continuous, lateral motion of drive belt 404. After installation of drive belt 404 through drum support 402 and drive sheaves 406, drum 306 may be free to passively translate laterally within frame 302 as line 106 spools and unspools thereon. In some embodiments, drive belt 404 may include one or more damping elements (not shown), such as a viscous damper, a magnetic eddy- current damper, or fluidic resistor to suppress oscillation and to encourage smooth motion of drum 306 during rotation.

[0053] To aid in stabilizing travel of drum 306, a support rail 408 may be provided on winch platform 202 and offset from drum 306 and drive belt 404. Support rail 408 may include a grooved inset 410 spanning across a width of support rail 408 on a face opposite to drum 306 (or back side), into which one or more support arms 412 may be received and retained. Each end of drum support 402 may include a support arm 412 projected therefrom, and each of these support arms 412 may pass under support rail 408 to be received within grooved inset 410 defined on the back side of support rail 408. The combination of support rail 408 and support arms 412 may provide stable lateral translation of drum 306 (e.g, along drive belt 404) while limiting or eliminating motion in the transverse direction (e.g, toward and away from support rail 408). As such, support rail 408 may define a back-drivable linear guide for guiding lateral translation of drum 306 while restricting motion in further directions.

[0054] In the illustrated embodiments, lateral motion of drum 306 may be limited by vertically protruding portions of frame 302, such that drum 306 interposes these portions of frame 302 and lateral motion of drum 306 is constrained by the span of drive belt 404 therebetween. In further embodiments, however, mechanical stops (not shown) may be provided along support rail 408 within grooved inset 410 to provide further limitations on lateral travel of drum 306. In further embodiments, one or more compression springs (not shown) may be provided within grooved inset 410 and mated to support arms 412. During translation of drum 306 and support arms 412, these compression springs may act as biasing elements and provide a weak restoring force to naturally urge drum 306 to maintain a neutral, centered state.

[0055] As depicted in FIG. 4, the footprint of compact self-translating winch 400 may be significantly reduced in comparison to traditional winch systems. Through the use of a back- drivable linear guide (support rail 408) and a passive lateral translation mechanism (drive belt 404), drum 306 may directly receive line 106 through aperture 204 without intermediate sheavesAtty. Docket No.: 081088-000030 or towers to reduce the fleet angle. Rather, compact self-translating winch 400 may maintain a near-zero fleet angle (e.g., less than or equal to about 1°), with a preferred fleet angle of or less than or equal to about 0.1°, to ensure neat spooling using the lateral component of tension in line 106, which may be provided by suspended mass 104 of FIG. 1, or any other applicable load. As compact self-translating winch 400 directly receives line 106, bending stress of line 106 may be significantly reduced through the elimination of intermediate sheaves. Further, the compact nature and limited bending of compact self-translating winch 400 may enable a reduction in total wraps of line 106 from a standard 8 layers down to a reduced 4 layers. This reduction in layers of line 106 may decrease torque variability in the spooling and unspooling process, while further reducing the footprint of compact self-translating winch 400 through a smaller diameter drum 306.

[0056] FIG. 5 is a schematic view of a chain-drive self-translating winch 500 in accordance with the present disclosure. Chain-drive self-translating winch 500 may include a first, housing frame 502 that provides an enclosure for the remaining components, as well as a second, drum frame 504 that houses translatable components, such as drum 306, to be translated within housing frame 502. In some embodiments, housing frame 502 and drum frame 504 may include substantially similar lengths, while housing frame 502 may include a width greater than that of drum frame 504. To facilitate translation of drum frame 504 within housing frame 502, one or more housing rails 506 may be provided on housing frame 502. Housing rails 506 may define lateral guides on which drum frame 504 may be slidably mounted to enable lateral translation while preventing motion in a transverse direction. In the illustrated embodiment, housing rails 506 are provided as an integral part of housing frame 502, such that housing rails 506 define the outer dimensions of housing frame 502. In further embodiments, however, housing rails 506 may be offset into or out of housing frame 502 without departing from the scope of the present disclosure.

[0057] Drum frame 504 may provide linear slides 508 to enable or encourage lateral translation of drum frame 504 along housing rails 506. Linear slides 508 may include wheels, bearings, or lubricated sleeves to retain drum frame 504 on housing rails 506, while limiting friction or resistance during sliding. As such, housing rails 506 may provide a back-drivable linear guide to limit translation of drum 306 as desired, while linear slides 508 may provide a passive, lateral translation mechanism to be actuated via a lateral component of tension in line 106.Atty. Docket No.: 081088-000030

[0058] In some embodiments, to supplement passive lateral translation of drum frame 504 and drum 306 within housing frame 502, chain-drive self-translating winch 500 may further include one or more active chain drives 510 and one or more passive chain sheaves 512. Active chain drives 510 may be powered to actively drive lateral translation of drum 306 via an added tensile force provided by a chain mated to drum frame 504. In some embodiments, active chain drives 510 may be provided on each of the left- and right-hand sides of housing frame 502 to enable active translation of drum frame 504 in either lateral direction. Each of active chain drives 510 may include a back-drivable actuator, such that motion of drum frame 504 independent of active chain drives 510 is not met with resistance. Passive chain sheaves 512 may be installed on an opposite lateral side of housing frame 502 to balance forces provided by active chain drives 510, and to maintain stability within housing frame 502. In further embodiments, however, active chain drives 510 may be omitted in favor of only passive chain sheaves 512, such that lateral motion of drum frame 504 is controlled only by the lateral component of tension in line 106.

[0059] In some embodiments, chain-drive self-translating winch 500 may include one or more stop rails 514 extending from a lateral side of housing frame 502 towards a center thereof. Stop rails 514 may include a lateral stop 516 mounted thereon and protruding vertically upward from stop rails 514. Lateral stop 516 may provide a travel limit for drum frame 504, such that drum frame 504 and drum 306 are unable to continue lateral translation. In some embodiments, lateral stops 516 may be slidably mounted to stop rails 514 to enable repositioning of lateral stops 516 thereon, such that varied sizes of drum 306 or different travel limits may be set at will. In the illustrated embodiment, drum 306 includes a winch motor 518 mounted thereto to provide a torque for spooling line 106 around drum 306, and winch motor 518 is free to travel along with drum 306 and drum frame 504. In further embodiments, however, winch motor 518 may be statically mounted to housing frame 502, such that drum 306 may translate laterally along an axle extending from winch motor 518 while winch motor 518 remains stationary.

[0060] FIG. 6 is a schematic top view of a smart self-translating winch 600 in accordance with the present disclosure. Smart self-translating winch 600 may be actively monitored or controlled to determine an optimal spooling position during operation. Accordingly, smart selftranslating winch 600 may include one or more force sensors 602 mounted within drum 306. Force sensors 602 may be mounted against axle 604 on which drum 306 may rotate, and force sensors 602 may be distributed to sense and signal forces in each cardinal direction. Suitable force sensors 602 may include strain gauges or load cells mounted on or against axle 604.Atty. Docket No.: 081088-000030Alternately, force sensors 602 may be incorporated into axle 604. such that axle 604 is a forcesensing axle that may directly report any experienced forces.

[0061] Force sensors 602 may be in direct communication with control box 606, which may be mounted on frame 302, as illustrated, or in wireless communication with a control box 606 externally located. As such, the location of control box 606 is exemplary and non-limiting. Control box 606 may include controller 608 and memory 610. such that control box 606 may receive signals from force sensors 602 and execute tasks based upon the received signals and instructions housed in memory 610. Controller 608 may be a processor and may be in communication with memory 610, which may be a machine-readable storage medium.

[0062] Smart self-translating winch 600 may further include a plurality of light gates 612 mounted on winch platform 202. Each light gate 612 may include corresponding transmitter 614 and receiver 616, such that light gates 612 may use infrared light to detect interruptions within them. Light gates 612 may similarly be in communication with control box 606, such that light gates 612 may provide signals to control box 606 for determining the location of line 106 during operation. Alternately, light gates 612 may provide signals to control box 606 for further determining the location of frame 302 and drum 306 during operation. Using both the location provided by light gates 612, and the applied forces determined by force sensors 602, control box 606 may be able to finely control motion via one or more actuators (not shown) of smart selftranslating winch 600 during operation to correct positioning of line 106 thereon.

[0063] FIG. 7 is a schematic top view of a track-based self-translating winch 700 in accordance with the present disclosure. Track-based self-translating winch 700 may be actively controlled, and may include one or more components of smart self-translating winch 600 (FIG. 6). Alternately, track-based self-translating winch 700 may be passively controlled, such that track-based self-translating winch 700 naturally responds to the lateral component of tension in line 106 to maintain a near-zero fleet angle for spooling on drum 306.

[0064] Track-based self-translating winch 700 may include a plurality of tracks 702 surrounding winch platform 202, which may provide one or more back-drivable linear guides via which drum 306 may passively or actively translate. Tracks 702 may be grooved to allow wheels 704 to be received therein. Wheels 704 may be positioned on opposing ends of rails 706a and 706b, which are mounted on, or otherwise mated to, frame 302. Frame 302 may be free to slide along rails 706a and 706b, such that during motion of rail 706a (horizontal rails), frame 302 may freely translate vertically along rails 706b (vertical rails). Similarly, during motionAtty. Docket No.: 081088-000030 along rails 706b, frame 302 may freely translate horizontally along rails 706a. Thus, translation along rails 706a and 706b may occur simultaneously. One or more bearings (not shown) may be included within frame 302, such that frame 302 may translate on the rails 706a and 706b with minimal resistance. Rails 706a and 706b may be alternatively shaped to include curved rails, such that rails 706a and 706b may match a contour of a curved winch platform (not shown) to further aid in translating track-based self-translating winch 700. In the illustrated embodiment, the combination of wdieels 704 and rails 706a,b may provide a passive translation mechanism operable to provide linear translation in each lateral direction while riding along the back- drivable linear guides of tracks 702.

[0065] As discussed above, track-based self-translating winch 700 may be actively controlled, and may include therein a control box similar to that of control box 606 (FIG. 6), as well as any sensing components previously discussed. In the case of track -based self-translating winch 700, the control box may receive force or positional data and may accordingly actuate a plurali ty of motors 708 to directly translate frame 302. Motors 708 may be installed on, or mated to, wheels 704. such that wheels 704 may be torqued to move along tracks 702. Alternately, motors 708 may be located on frame 302, such that frame 302 is moved along rails 706a and 706b by motors 708. Further, motors 708 may be embedded within tracks 702, such that wheels 704 may be pulled or pushed along tracks 702 in a desired direction to translate frame 302. Regardless of the location of motors 708, frame 302 may be translated to reduce the force experienced by drum 306, and an optimal position may be determined for wrapping line 106 around drum 306. In these embodiments, while tracks 702 provide the back-drivable linear guides for lateral translation, motors 708 may act as back-drivable actuators operable to supplement passive translation provided by tension in line 106 without interfering with or resisting the forces provided by line 106.

[0066] As an alternative, track-based self-translating winch 700 may be passively controlled, such that components facilitating smart control may be omitted. Further, in the case of passive control, motors 708 may be omitted, such that track-based self-translating winch 700 is translated along the rails 706a and 706b and tracks 702 in response to a force applied by line 106. As line 106 pulls against dmm 306, track -based self-translating winch 700 may be similarly pulled along rails 706a and 706b and tracks 702 to reduce the applied force. Accordingly, as line 106 is retracted in the “R” direction (FIG. 3), line 106 may naturally coil in an optimal pattern or location based upon the direction of the force applied by line 106 to drum 306.Atty. Docket No.: 081088-000030

[0067] FIG. 8 is a schematic top view of a floating self-translating winch 800 in accordance with the present disclosure. Floating self-translating winch 800 may include frame 302 and drum 306 as shown for previous winches herein. However, in the case of floating self-translating winch 800, winch platform 202 may be divided into a floating platform 802 and a flotation platform 804. Floating platform 802 may include frame 302 and drum 306 mounted thereon, such that movement of floating platform 802 may similarly move frame 302 and drum 306. Floating platform 802 may be free to translate in any direction on flotation platform 804 and may be constrained therein by a plurality of guards 806 surrounding flotation platform 804. Aperture 204 through which line 106 travels may similarly include lip 808 to separate aperture 204 from flotation platform 804. As line 106 pulls or pushes against drum 306, floating platform 802 may translate atop flotation platform 804 to compensate for, and reduce, the force of line 106.

[0068] Flotation platform 804 may be formed of a low-friction or lightweight material to facilitate motion of floating platform 802 atop flotation platform 804. Flotation platform 804 may form a basin or otherwise have concavity, such that a fluid may be introduced therein. The fluid may be a grease, oil, or other lubricious fluid, and flotation platform 804 may be filled to create a lubricious fluid bath. Accordingly, floating platform 802 may slide or bob along the fluid within flotation platform 804. The minimal friction provided by the fluid in flotation platform 804 may facilitate translation of floating platform 802 in response to an applied force without wear to line 106 of floating self-translating winch 800. In some embodiments, flotation platform 804 and guards 806 may define a linear or lateral path for floating platform 802 to prevent vertical travel of floating platform 802 during spooling. In these embodiments, guards 806 may provide a back-drivable linear guide for translation of floating platform 802, such that drum 306 may spool line 106 at a near-zero fleet angle using the lateral component of tension in line 106 during spooling.

[0069] Alternately, floating platform 802 may include permanent magnets (e.g, N-pole permanent magnets) embedded therein, and flotation platform 804 may include corresponding electromagnetic coils (e.g.. N-pole electromagnetic coils). During operation, the corresponding polarization may generate magnetic levitation of floating platform 802 atop flotation platform 804. The magnetic levitation of floating platform 802 may provide near-zero friction, such that floating platform 802 may translate on flotation platform 804 in any direction in response to forces applied by line 106. Further alternately, floating platform 802 may be stationary and mayAtty. Docket No.: 081088-000030 include the electromagnetic coils, while flotation platform 804 includes permanent magnets therein. As such, line 106 may push or pull against aperture 204 and direct movement of flotation platform 804 beneath floating platform 802 to reduce the applied force of line 106 on drum 306.

[0070] Floating self-translating winch 800 may optionally incorporate at least some components or concepts of smart self-translating winch 600 (FIG. 6). Floating self-translating winch 800 may include a control box similar to control box 606 of FIG. 6 for controlling the electromagnetic coils discussed above and actively moving floating self-translating winch 800. In these embodiments, active motion of floating self-translating winch 800 may be provided by a back-drivable actuator operable to supplement passive translation of floating platform 802 without interfering with or resisting the forces provided by line 106. Further, floating selftranslating winch 800 may include sensors or positioning systems, also similar to those discussed in reference to FIG. 6, such that the position and condition of floating self-translating winch 800 may be tracked. Floating self-translating winch 800 may replace, or supplement, force sensors 602 of FIG. 6 with an IMU system, including an accelerometer, gyroscope, and magnetometer. Further, floating self- translating winch 800 may replace, or supplement, light gates 612 of FIG. 6 with a LIDAR system to likewise capture the position of floating self-translating winch 800.

[0071] FIG. 9 is a schematic side view of a labyrinthine self-translating winch 900 in accordance with the present disclosure. As discussed above, drum 306 may be a grooved drum with a groove pitch approximately equal to a diameter of line 106, such that spooling of line 106 is facilitated by the grooves shown in FIG. 9. Similar to floating self-translating winch 800, discussed above, labyrinthine self-translating winch 900 may include winch platform 202 divided into moving platform 902 and stationary platform 904. Moving platform 902 may include frame 302 and drum 306 mounted thereon, and may be translatable atop stationary platform 904 via post 906 projecting downward from moving platform 902. Stationary platform 904 may include labyrinth 908 defined therein, such that post 906 may enter and translate within labyrinth 908 as forces are applied to drum 306 via line 106. Labyrinth 908 may provide a back- drivable linear guide operable to define a path of translation for drum 306 to maintain a nearzero fleet angle for line 106 during spooling. The shape of labyrinth 908 is not believed to be particularly limited. FIG. 10 shows an exemplary shape for labyrinth 908.

[0072] FIG. 10 is a schematic top view' of stationary' platform 904 with rectilinear labyrinth 1002 included therein. Rectilinear labyrinth 1002 may snake back and forth across stationary' platform 904. such that post 906 (FIG. 9) is limited in motion to the rectilinear directions shownAtty. Docket No.: 081088-000030 in FIG. 10. As line 106 (not shown) pulls against drum 306 (FIG. 9), moving platform 902 may translate in the pattern of rectilinear labynnth 1002 to coil line 106 in a desired pattern on drum 306.

[0073] In further embodiments, labyrinth 1002 may be replaced by any eccentric mechanism operable to convert rotational energy into lateral motion without departing from the scope of the present disclosure. As non-limiting examples, the eccentric mechanism may include any of a scotch yoke mechanism, a cam and follower mechanism, an eccentric shaft, compliant linkages, a spring-biased floating cam follower, and any combination thereof. In these embodiments, post 906 of FIG. 9 may be mated to one or more of these eccentric mechanisms to enable smooth lateral translation of drum 306 (not shown in FIG. 10) during spooling, such that these eccentric mechanisms provide a passive lateral translation mechanism for drum 306. Further, the eccentric mechanism may be defined to provide a constant translation velocity during spooling, as well as a smooth reversal of direction at the limits of lateral travel.

[0074] FIG. 11 is a schematic side view of a solar self-translating winch 1100 in accordance with the present disclosure. Solar self-translating winch 1100 may incorporate any of the components of winches 300, 400, 500, 600, 700, 800, or 900 to promote active centering thereof. Solar self-translating winch 1100 may form a closed power system, such that any sensors, motors, controllers, or positioning systems may be powered directly by one or more solar panels 1102. Solar panels 1102 may be mounted atop a plurality of risers 1104, which project solar panels 1102 above drum 306. As shown, risers 1104 may be installed atop frame 302, such that solar panels 1102 may be translatable with frame 302 during operation. Alternately, risers 1104 may project from winch platform 202, such that solar panels 1102 are held in a stationary position, which may or may not overlay drum 306 during operation.

[0075] FIG. 12 is a schematic of an auto-lubricating potential energy conversion system 1200 housed in a non-producing well 102 in accordance with the present disclosure. Autolubricating potential energy conversion system 1200 may include both winch 112 and sheave pulley 110, as illustrated, or may incorporate any of the designs of FIGS. 2-11 in which a sheave pulley is omitted. As with potential energy conversion system 200, auto-lubricating potential energy conversion system 1200 may include a mass 104 lowered on line 106 within well 102 between surface 108 and plug 103. Well 102 for auto-lubricating potential energy’ conversion system 1200 may be partially filled with a fluid 1202, as discussed above.Atty. Docket No.: 081088-000030

[0076] Fluid 1202 may include, for example, aqueous fluids, including any cased- wellcompatible aqueous fluids known in the art of wellbore drilling and production. Suitable fluids 1202 may include water, optionally containing one or more additives, including additives to minimize corrosion and / or modify various rheological properties. Alternately, fluid 1202 may include high-density brines or chemicals to maintain hydrostatic pressure to minimize well casing damage and limit inadvertent ingress of hydrocarbons into the interval where mass 104 resides. In non-limiting examples, fluid 1202 may further include one or more of biocides, anticorrosion chemicals, and scale inhibitors to prevent damage to the potential energy conversion systems during extended deployment in the well.

[0077] As line 106 is raised and lowered, and travels across both sheave pulley 110 and winch 112, the wire rope comprising line 106 may begin to wear and degrade. Accordingly, lubrication of line 106 may extend the lifetime of the wire rope and auto-lubricating potential energy conversion system 1200. In auto-lubricating potential energy conversion system 1200, lubrication fluid 1204, such as a mineral oil-based lubricant, may be installed atop fluid 1202 present in the well 102. Lubrication fluid 1204 possesses a densify lower than that of fluid 1202 and is immiscible with fluid 1202, such that lubrication fluid 1204 naturally rests atop fluid 1202 without mixing. Lubrication fluid 1204 may be highly stable to enable a longer lifetime within well 102 and may be chosen to limit or eliminate any negative environmental impact. Further, lubrication fluid 1204 may be of a low viscosity, such that lubrication fluid 1204 may enter the wire rope of line 106 without externally applied pressure as line 106 passes through lubrication fluid 1204. Thus, as mass 104 is raised and lowered, line 106 will naturally pass through and passively receive lubrication fluid 1204 to increase efficiency and lifetime of the line 106. Lubrication fluid 1204 may be provided atop fluid 1202 in sufficient quantify for long-term use or may be supplemented with further lubrication fluid 1204 during operation if quantify of lubrication fluid 1204 drops below desired levels.

[0078] Alternatives of the auto-lubricating potential energy conversion system 1200 are described hereinafter in reference to FIGS. 13 and 14, in which a lubrication fluid is supplied internally within sheave pulley 110.

[0079] FIG. 13 is a schematic of a first configuration of an auto-lubricating cover 1300 within a potential energy conversion system positioned above a non-producing well 102 in accordance with the present disclosure. Auto-lubricating cover 1300 may encase sheave pulley 110, and may receive line 106 during operation. Alternately, auto-lubricating cover 1300 mayAtty. Docket No.: 081088-000030 encase winch 112 of FIG. 1 or any of winches 300, 400, 500, 600, 700, 800. or 900. particularly in systems omitting sheave pulley 110. Auto-lubricating cover 1300 may include, or be coupled to, lubricant tank 1302, which supplies lubrication fluid 1304 to auto-lubricating cover 1300. Alternately, lubricant tank 1302 may be externally located and in fluid communication with autolubricating cover 1300 without departing from the scope of this disclosure. Lubrication fluid 1304 may be similar to lubrication fluid 1204 of FIG. 12, or may be a traditional grease, oil. or other lubricating agent that is readily dispensed from lubricant tank 1302.

[0080] Auto-lubricating cover 1300 may include main body 1306, which encases sheave pulley 110 and limits exposure of lubrication fluid 1304 to the surrounding environment. Main body 1306 may include well-side aperture 1308 that enables passage of line 106 from sheave pulley 110 into well 102. Main body 1306 may further include winch-side aperture 1310 that enables passage of line 106 from sheave pulley 110 towards the winch (not shown). Main body 1306 may include dispenser 1312 therein, which receives lubrication fluid 1304 from lubricant tank 1302 and dispenses lubrication fluid 1304 to line 106 as line 106 passes over sheave pulley 110. Dispenser 1312 may include nozzle 1314 for targeted application of lubrication fluid 1304 to line 106.

[0081] Dispenser 1312 may be a pump that is configured to slowly dispense lubrication fluid 1304 at a specified flow rate. The flow- rate of lubrication fluid 1304 may be limited, such that line 106 is gradually and continuously lubricated without over-dispensing. Dispenser 1312 may be mated to, or in communication with, motor 1316 that pow ers dispenser 1312 to control the flow rate. Alternately, dispenser 1312 may be self-driven and may be in communication with an internal or external pow er source to provide the energy for operation.

[0082] FIG. 14 is an illustration of a rotationally -powered auto-lubricating cover 1400 within a potential energy conversion system positioned above a non-producing well 102 in accordance with the present disclosure. Rotationally-powered auto-lubricating cover 1400 may include similar features to auto-lubricating cover 1300 of FIG. 13 and may be better understood by reference thereto. Rotationally powered auto-lubricating cover 1400 may include main body- 1306 around the sheave pulley 110 and may utilize dispenser 1312 for dispensing a lubrication fluid to line 106 as line 106 passes over the sheave pulley 110. As above, rotationally powered auto-lubricating cover 1400 may alternately encase winch 112 of FIG. 1 or any of winches 300, 400, 500, 600, 700, 800, or 900, particularly in systems omitting sheave pulley 110. In place ofAtty. Docket No.: 081088-000030 a motor 1316 or a power source, sheave-powered auto-lubricating cover 1400 utilizes the rotation of sheave pulley 110 or winch 112, to power dispenser 1312.

[0083] Hence, rotationally -powered auto-lubricating cover 1400 may include one or more gearboxes 1402 and one or more axles 1404, which enable transfer of torque from sheave pulley 110 to dispenser 1312. As line 106 passes over sheave pulley 110, sheave pulley’ 110 may rotate around a central axis. Sheave gearbox 1402a may be rotationally mated to sheave pulley 110, such that rotation of sheave pulley 1 10 may rotate the internal gears of gearbox 1402. Sheave gearbox 1402a may be mated to dispenser gearbox 1402b via axle 1404 to transfer the torque between gearboxes 1402a,b. Dispenser gearbox 1402b may transfer the torque to dispenser 1312 to power any pumping mechanisms included therein. Accordingly, any rotational motion of sheave pulley 110 may power dispenser 1312 and enable a closed system for powering rotationally powered auto-lubricating cover 1400.

[0084] Embodiments disclosed herein include:

[0085] A. Potential energy conversion systems comprising: a movable mass suspended by a line in a non-producing well; a self-centering winch installed on a winch platform over the nonproducing well; a motor coupled to the self-centering winch and operable to spool the line on a drum of the self-centering winch; and a generator coupled to the self-centering winch and operable to produce electricity when lowering the movable mass.

[0086] B. Potential energy conversion systems comprising: a movable mass suspended by a line in a non-producing well; a winch; a motor coupled to the winch and operable to spool the line on a drum of the winch; a generator coupled to the winch and operable to produce electricity' when lowering the movable mass; a sheave pulley interposed between the non-producing well and the winch and operable to guide the line while spooling onto the drum of the winch; and an auto-lubricating cover comprising a main body encasing the sheave pulley or winch, wherein the auto-lubricating cover is operable to dispense a lubrication fluid to the line as the line passes over the sheave pulley or winch.

[0087] C. Self-centering winches, the self-centering winches comprising: a frame comprising a first arm and a second arm; a drum interposed between the first arm and the second arm of the frame; a line attached to and spooling around the drum of the self-centering winch; a winch platform upon which the frame is installed; and a conveyor operable to translate the frame on the w inch platform.Atty. Docket No.: 081088-000030

[0088] D. Auto-lubricating covers comprising: a main body sized to encase a sheave pulley or winch and defining a plurality of apertures as a path for a line passing over the sheave pulley or winch; a lubricant tank mounted on the main body; a powered dispenser installed within the main body and in fluid communication with the lubricant tank; and a nozzle installed on the powered dispenser for dispensing a lubrication fluid from the lubricant tank to the path for the line.

[0089] E. Potential energy conversion systems comprising: a movable mass suspended by a line in a non-producing well; a winch: a motor coupled to the winch and operable to spool the line on a drum of the winch; a generator coupled to the winch and operable to produce electricity when lowering the movable mass; a sheave pulley interposing the non-producing well and the winch and operable to guide the line while spooling onto the drum of the winch; a fluid at least partially filling the non-producing well; and a lubrication fluid of low er density than the fluid at least partially filling the non-producing well, wherein the lubrication fluid is immiscible with and lower density than the fluid at least partially filling the non-producing well.

[0090] Each of embodiments A. B, C, D. and E may have one or more of the following additional elements in any combination:

[0091] Element 1: wherein the self-centering winch comprises one or more of a force sensor, a gy roscope, an accelerometer, a magnetometer, or any combination thereof within the drum.

[0092] Element 2: wherein the winch platform comprises one or more light gates, a LIDAR system, or any combination thereof installed thereon and operable to track a position of the self- centering winch, the line, or a combination thereof.

[0093] Element 3: wherein the self-centering winch comprises: a frame surrounding the drum; one or more first rails mounted on the frame in a horizontal direction and one or more second rails mounted on the frame in a vertical direction; one or more wheels mated to an end of each of the one or more first rails and the one or more second rails; and one or more tracks installed on the winch platform and sized to receive the one or more wheels.

[0094] Element 4: wherein the self-centering winch further comprises: a plurality of motors operable to translate the one or more wheels within the one or more tracks; and a control box comprising a controller and a memory, wherein the memory stores instructions readable by the controller to control the plurality7of motors.Atty. Docket No.: 081088-000030

[0095] Element 5: wherein the winch platform comprises: a flotation platform comprising a lip surrounding a perimeter of the flotation platform; and a floating platform atop the flotation platform, wherein the self-centering winch is installed thereon.

[0096] Element 6: wherein the flotation platform and floating platform comprise corresponding permanent magnets and electromagnetic coils, and wherein the floating platform is magnetically levitated over the flotation platform.

[0097] Element 7: wherein the flotation platform is at least partially filled with a fluid, and the floating platform translates upon the fluid over the flotation platform.

[0098] Element 8: wherein the floating platform comprises a post projecting downward from the floating platform, wherein the flotation platform comprises a labyrinth, and wherein the post is receivable within the labyrinth to guide movement of the floating platform across the flotation platform.

[0099] Element 9: wherein the auto-lubricating cover comprises a lubricant tank mounted thereon.

[0100] Element 10: wherein the main body defines a well-side aperture and a winch-side aperture as a path of travel for the line through the auto-lubricating cover.

[0101] Element 11: wherein the auto-lubricating cover comprises a powered dispenser for actively dispensing the lubrication fluid.

[0102] Element 12: further comprising one or more gearboxes and one or more axles connecting the powered dispenser and the sheave pulley or winch, wherein rotation of the sheave pulley or winch provides power to the powered dispenser.

[0103] Element 13: wherein the conveyor comprises: one or more first rails mounted on the frame in a horizontal direction and one or more second rails mounted on the frame in a vertical direction; one or more wheels mated to an end of each of the one or more first rails and the one or more second rails; and one or more tracks installed on the winch platform and sized to receive the one or more wheels.

[0104] Element 14: wherein the conveyor comprises: a flotation platform comprising a lip surrounding a perimeter of the flotation platform; and a floating platform atop the flotation platform, wherein the self-centering winch is installed thereon, wherein the flotation platform and floating platform comprise corresponding permanent magnets and electromagnetic coils, and wherein the floating platform is magnetically levitated over the flotation platform.Atty. Docket No.: 081088-000030

[0105] Element 15: further comprising one or more gearboxes and one or more axles operable to connect the powered dispenser to the sheave pulley or winch, wherein rotation of the sheave pulley or winch provides power to the powered dispenser.

[0106] By way of non-limiting example, exemplary combinations applicable to A and B include, but are not limited to, 1 and any one or more of 2 to 15; 2 and any one or more of 1 and 3 to 15; 3 and any one or more of 1 to 2 and 4 to 15; 4 and any one or more of 1 to 3 and 5 to 15; 5 and any one or more of 1 to 4 and 6 to 15; 6 and any one or more of 1 to 5 and 7 to 15; 7 and any one or more of 1 to 6 and 8 to 15; 8 and any one or more of 1 to 7 and 9 to 15; 9 and any one or more of 1 to 8 and 10 to 15; 10 and any one or more of 1 to 9 and 11 to 15; 11 and any one or more of 1 to 10 and 12 to 15; 12 and any one or more of 1 to 11 and 13 to 15; 13 and any one or more of 1 to 12 and 14 to 15; 14 and any one or more of 1 to 13 and 15 to 15; 15 and any one or more of 1 to 14. Additional combinations applicable to A and B include, but are not limited to: 3 and 4; 5 and 6; 5 and 7; 5 and 8; and 11 and 12.

[0107] Additional embodiments disclosed herein include:

[0108] Embodiment 1 ’. A potential energy conversion system comprising: a movable mass suspended by a line in a non-producing well; a self-translating winch mounted to a winch platform over the non-producing well, the self-translating winch including: a drum coupled to the line and operable to spool the line thereon, a back-drivable linear guide mounting the drum to the winch platform, and a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line; and a motor coupled to the self-translating winch and operable to spool the line on the drum of the self-translating winch.

[0109] Embodiment 2‘ . The potential energy conversion system of Embodiment 1’, wherein the back-drivable linear guide is a support rail to enable lateral translation of the drum while preventing translation in a transverse direction.

[0110] Embodiment 3’. The potential energy conversion system of Embodiment 2’, wherein the passive linear translation mechanism is a linear drive including a drive belt and one or more drive sheaves, and wherein the drum is mounted to the drive belt for lateral translation.

[0111] Embodiment 4’. The potential energy conversion system of any one of Embodiments l’-3’, wherein the drum is a grooved drum including a groove pitch of about a diameter of the line.Atty. Docket No.: 081088-000030

[0112] Embodiment 5’. The potential energy conversion system of any one of Embodiments l’-4’, wherein the back-drivable linear guide includes one or more rails mounted on the frame in a lateral direction, and wherein the passive lateral translation mechanism includes linear slides mounted on the one or more rails to enable lateral motion of the drum along the one or more rails.

[0113] Embodiment 6’. The potential energy' conversion system of Embodiment 5’, further comprising: one or more back-drivable actuators operable to supplement passive translation of the drum without resisting motion against the one or more back-drivable actuators from tension in the line.

[0114] Embodiment 7’. The potential energy conversion system of any one of Embodiments l’-6’, wherein the self-translating winch further includes a sensing element selected from the group consisting of a force sensor, a gyroscope, an accelerometer, a magnetometer, and any combination thereof.

[0115] Embodiment 8'. The potential energy conversion system of any one of Embodiments l’-7’, wherein the winch platform comprises one or more light gates, a LIDAR system, or any combination thereof installed thereon and operable to track a position of the self-translating winch, the line, or a combination thereof.

[0116] Embodiment 9’. The potential energy conversion system of any one of Embodiments 1 ’-8’, wherein the back-drivable linear guide is a flotation platform comprising a lip surrounding a perimeter of the flotation platform, and wherein the passive lateral translation mechanism is a floating platform housing the drum and floating atop the flotation platform.

[0117] Embodiment 10‘. The potential energy' conversion system of any one of Embodiments 1’ -9', wherein the passive lateral translation mechanism is selected from the group consisting of a scotch yoke mechanism, a cam and follower mechanism, an eccentric shaft, a compliant linkage, a spring-biased floating cam follower, and any combination thereof.

[0118] Embodiment 11’. A method of spooling a line, the method comprising: mounting a drum of a winch to a back-drivable linear guide provided on a frame of the winch; mating the drum with a passive lateral translation mechanism provided on the frame of the winch, the passive lateral translation mechanism operable to translate the drum along the back-drivable linear guide; mating a first end of the line to the drum, wherein a second end of the line is mated to a load to be raised and lowered by the winch; rotating the winch via a winch motor to spool the line onto the drum and raise the load; translating the drum along the back-drivable linearAtty. Docket No.: 081088-000030 guide in response to a lateral component of tension in the line during spooling; and receiving the line on the drum with a fleet angle less than or equal to about 1° via the passive lateral translation mechanism.

[0119] Embodiment 12’. The method of Embodiment 11’, wherein the passive lateral translation mechanism maintains a fleet angle less than or equal to about 0. 1°.

[0120] Embodiment 13’. The method of Embodiment 11’ or Embodiment 12’. wherein the drum is a grooved drum, and wherein receiving the line on the drum includes receiving the line within a groove pitch about equal to a diameter of the line.

[0121] Embodiment 14'. The method of any one of Embodiments ll’-13’, further comprising: supplementing passive translation of the drum on the back-drivable linear guide with a back-drivable actuator operable to translate the drum in a first direction without resisting motion in a second direction.

[0122] Embodiment 15’. The method of Embodiment 14’, further comprising: sensing a position of the drum, the line, or a combination thereof via a sensing element installed on the frame of the winch; and activating the back-drivable actuator to translate the drum to a desired location based upon the position sensed by the sensing element.

[0123] Embodiment 16’. A self-translating winch, the self-translating winch comprising: a frame providing one or more support surfaces; a grooved drum coupled to a first end of a line and operable to spool the line thereon; a back-drivable linear guide mounting the drum to the frame between the one or more support surfaces; a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line; and a winch motor mated with the grooved drum and operable to provide torque for spooling the line thereon, wherein a second end of the line is attached to a load to be raised or lowered by the self-translating winch.

[0124] Embodiment 17’. The self-translating winch of Embodiment 16’, wherein the passive lateral translation mechanism is selected from the group consisting of a scotch yoke mechanism, a cam and follower mechanism, an eccentric shaft, a compliant linkage, a spring-biased floating cam follower, and any combination thereof.

[0125] Embodiment 18’. The self-translating winch of Embodiment 16’ or Embodiment 17’, wherein the winch motor is statically mounted to the frame of the winch, and wherein the grooved drum is free to translate within the frame independently of the winch motor.Atty. Docket No.: 081088-000030

[0126] Embodiment 19’. The self-translating winch of any one of Embodiments 16’-18’, wherein the passive linear translation mechanism is a linear drive including a drive belt and one or more drive sheaves, and wherein the drum is mounted to the drive belt for lateral translation.

[0127] Embodiment 20’. The self-translating winch of any one of Embodiments 16’-19’, wherein the grooved drum receives the line directly from the load without any intermediate sheaves or compensators interposing the grooved drum and the line.

[0128] The use of directional terms such as above, below, upper, lower, upward, downward, left, right, and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure.

[0129] All documents described herein are incorporated by reference herein for purposes of all jurisdictions where such practice is allow ed, including any priority documents and / or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the disclosure be limited thereby. For example, the compositions described herein may be free of any component or composition not expressly recited or disclosed herein. Any method may lack any step not recited or disclosed herein. Likewise, the term “comprising” is considered synonymous with the term “including.” Whenever a method, composition, element, or group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[0130] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary' depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine ofAtty. Docket No.: 081088-000030 equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0131] Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, "‘from about a to about b," or, equivalently, “from approximately a to b,” or. equivalently, “from approximately a-b’?) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary’ meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,"’ as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0132] One or more illustrative embodiments are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment of the present disclosure, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related, and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for one of ordinary’ skill in the art and having the benefit of this disclosure.

[0133] Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to one having ordinary skill in the art and having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as descnbed in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified, and all such variations are considered within the scope and spirit of the present disclosure. The embodiments illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and / or any optional element disclosed herein.

Claims

1. Atty. Docket No.: 081088-000030CLAIMSWhat is claimed is:

1. A potential energy conversion system comprising: a movable mass suspended by a line in a non-producing well; a self-translating winch mounted to a winch platform over the non-producing well, the self-translating winch including: a drum coupled to the line and operable to spool the line thereon, a back-drivable linear guide mounting the drum to the winch platform, and a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line; and a motor coupled to the self-translating winch and operable to spool the line on the drum of the self-translating winch.

2. The potential energy conversion system of claim 1, wherein the passive lateral translation mechanism is selected from the group consisting of a scotch yoke mechanism, a cam and follower mechanism, an eccentric shaft, a compliant linkage, a spring-biased floating cam follower, and any combination thereof.

3. The potential energy conversion system of claim 1, wherein the back-drivable linear guide is a flotation platform comprising a lip surrounding a perimeter of the flotation platform, and wherein the passive lateral translation mechanism is a floating platform housing the drum and floating atop the flotation platform.

4. The potential energy conversion system of claim 1, wherein the back-drivable linear guide includes one or more rails mounted on the w inch platform in a lateral direction, and wherein the passive lateral translation mechanism includes linear slides mounted on the one or more rails to enable lateral motion of the drum along the one or more rails.Atty. Docket No.: 081088-0000305. The potential energy conversion system of claim 1. wherein the back-drivable linear guide is a support rail to enable lateral translation of the drum while preventing translation in a transverse direction.

6. The potential energy conversion system of claim 5. wherein the passive linear translation mechanism is a linear drive including a drive belt and one or more drive sheaves, and wherein the drum is mounted to the drive belt for lateral translation.

7. The potential energy conversion system of any one of claims 1-6, wherein the drum is a grooved drum including a groove pitch of about a diameter of the line.

8. The potential energy conversion system of any one of claims 1-6, further comprising: one or more back-drivable actuators operable to supplement passive translation of the drum without resisting motion against the one or more back-drivable actuators from tension in the line.

9. The potential energy conversion system of any one of claims 1-6, wherein the self-translating winch further includes a sensing element selected from the group consisting of a force sensor, a gyroscope, an accelerometer, a magnetometer, and any combination thereof.

10. The potential energy conversion system of any one of claims 1-6, wherein the winch platform comprises one or more light gates, a LIDAR system, or any combination thereof installed thereon and operable to track a position of the self-translating winch, the line, or a combination thereof.

11. A method of spooling a line, the method comprising: mounting a drum of a winch to a back-drivable linear guide provided on a frame of the winch; mating the drum with a passive lateral translation mechanism provided on the frame of the winch, the passive lateral translation mechanism operable to translate the drum along the back-drivable linear guide;Atty. Docket No.: 081088-000030 mating a first end of the line to the drum, wherein a second end of the line is mated to a load to be raised and lowered by the winch; rotating the winch via a winch motor to spool the line onto the drum and raise the load; translating the drum along the back-drivable linear guide in response to a lateral component of tension in the line during spooling; and receiving the line on the drum with a fleet angle less than or equal to about 1° via the passive lateral translation mechanism.

12. The method of claim 11, further comprising: supplementing passive translation of the drum on the back-drivable linear guide with a back-drivable actuator operable to translate the drum in a first direction without resisting motion in a second direction.

13. The method of claim 12, further comprising: sensing a position of the drum, the line, or a combination thereof via a sensing element installed on the frame of the winch; and activating the back-drivable actuator to translate the drum to a desired location based upon the position sensed by the sensing element.

14. The method of any one of claims 11-13, wherein the passive lateral translation mechanism maintains a fleet angle less than or equal to about 0.1°.1 . The method of any one of claims 11-13. wherein the drum is a grooved drum, and wherein receiving the line on the drum includes receiving the line within a groove pitch about equal to a diameter of the line.

16. A self-translating winch, the self-translating winch comprising: a frame providing one or more support surfaces; a grooved drum coupled to a first end of a line and operable to spool the line thereon; a back-drivable linear guide mounting the drum to the frame between the one or more support surfaces;Atty. Docket No.: 081088-000030 a passive lateral translation mechanism coupled to the drum and operable to translate the drum along the back-drivable linear guide in response to tension of the line; and a winch motor mated with the grooved drum and operable to provide torque for spooling the line thereon, wherein a second end of the line is attached to a load to be raised or lowered by the self-translating winch.

17. The self-translating winch of claim 16, wherein the passive lateral translation mechanism is selected from the group consisting of a scotch yoke mechanism, a cam and follower mechanism, an eccentric shaft, a compliant linkage, a spring-biased floating cam follower, and any combination thereof.

18. The self-translating winch of claim 16, wherein the passive lateral translation mechanism is a linear drive including a drive belt and one or more drive sheaves, and wherein the drum is mounted to the drive belt for lateral translation.

19. The self-translating winch of any of claims 16-18, wherein the winch motor is statically mounted to the frame of the winch, and wherein the grooved drum is free to translate within the frame independently of the winch motor.

20. The self-translating winch of any of claims 16-18, wherein the grooved drum receives the line directly from the load without any sheaves or compensators interposing the grooved drum and the line.

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