Patent Application
20190264520
The field of invention is manufacturing, storage, transportation and use of downhole tools, including downhole tools with a protective cover. Embodiments of degradable and abradable protective covers closely fitted about downhole tools, and methods and devices for making, packaging and using downhole tools with such covers are disclosed. Protective covers for downhole tools to help protect the downhole tools in storage, shipment and at the well site from humidity and handling and during use downhole are disclosed. The cover may be a sleeve, bag or sheet applied after the tool is manufactured. In an embodiment, the cover is comprised of a material that degrades in acidic aqueous downhole fluids. A device for and method of applying the cover is disclosed, including shrinking the cover onto the assembled tool to create a tool and wrap assembly for transportation and use downhole. A container for transporting cylindrical downhole tools is also disclosed.
Downhole tools for use in oil wells, upon being manufactured, are typically individually stored in cardboard boxes and crated or stacked on a pallet and strapped down for storage and shipment to an end-user at a well site, where the tools are unboxed and then used downhole. Boxed, crated and palleted tools are subject to humidity during storage and transport. This may be particularly disadvantageous for tools which are subject to degradation due to humidity. Well sites are often littered with scores of discarded cardboard boxes, crates and pallets which were used to deliver downhole tools for use at the well. Consumption of boxes, crates and pallets and littering well sites with them degrades the environment. Landowners often complain of discarded boxes, crates and pallets left on their land when the well site crew leaves the well site. Current typical use of typical downhole tool packaging and shipment materials sometimes creates a negative public relations environment for the oil industry.
Multiple embodiments of protective covers that may be pre-formed as sleeves or bags are disclosed. In an embodiment, a sleeve is preformed and open at both ends, or is preformed and open at one end and closed at the other end. In an embodiment, flexible protective cover material is drawn from a roll of the material and formed on the downhole tool by encircling or wrapping the downhole tool with the material, cutting the material to create an edge, and joining the edge with the material wrapped about the tool. In some embodiments, after the cover material is placed about the tool, the wrap is shrunk about the tool to tightly conform the material to the irregular shape of the tool, including its slips, cones and elastomeric seal, and particularly about the slip's sharp inserts and withers. Shrinking may be accomplished with heat or cold shrink processes. Shrinking may be accomplished by stretching an elastic sheet of cover material about the tool, securing it about the tool in a stretched condition, and letting the elastic material shrink. Combinations of the processes and materials may be employed.
The cover may act as a protective layer, protecting, for example, an oil worker who is handling the tool from the tool's outer sharp edges, such as its slip's sharp withers or inserts, or the tool's threads or end edges. The cover also protects the elements of the tool itself. The cover may help protect the tool as it moves downhole from abrasion from the inner surface of the casing of a cased wellbore and from abrasive materials in the drilling fluid or other downhole fluids. The cover may assist in more accurately predicting and controlling time periods for degradable tool degradation and release from the casing.
Covers are provided which snuggly cover at least part of an assembled downhole tool. The cover may be rigid or flexible. The cover may be a circular sleeve or tube used for packaging, safety, convenience, and other downhole advantages. For example, it may keep the tool free of moisture and secure prior to its use downhole and for a predetermined temporary duration downhole. Its ends may be sealed or capped after a tool is inserted in it.
Covers are described herein which are a: (1) pre-formed tube, with both ends open, (2) preformed bag, with one and open, and (3) film (not preformed) In some embodiments, the protective cover or wrap may be degradable, meaning the wrap breaks down and loses its physical integrity and ceases to protect the tool due to contact with the well's downhole fluids. Cover degradation may be caused by reaction of the cover to the heat and chemistry of the downhole fluid, including the fluid's salinity and pH. Degradability may include biodegradability and compostability. A product is compostable if it degrades into non-toxic constituents. A degradable product may be soluble. Processes of degradation and conditions under which they occur may be found in U.S. patent application Ser. No. 15/355,346, filed Nov. 18, 2016; and Ser. No. 16/182,206, filed Nov. 6, 2018, both incorporated herein by reference. These applications describe degradation of polymer elements in downhole tools, such as mandrels, seals, slips and cones. Applicant's covers, in some embodiments, are adapted to degrade in or under the physical and chemical conditions described in these applications, but, in some embodiments, at a rate of degradation that is faster than the rate of degradation of the elements of the downhole tools. For example, where a downhole tool element degrades to cease functioning in a predetermined time period, such as within 10 to 12 hours, or a chosen number of days, Applicant's cover or wrap, in some embodiments, is adapted to initially protect the downhole tool, but then dissolve, degrade or otherwise lose its physical integrity within 1-240 minutes of contact with a downhole fluid. In some embodiments, the cover will degrade and permit substantial tool/downhole fluid contact in as quickly as one minute after being immersed in the downhole fluid. In other embodiments, the cover's degradation occurs within 1-15 minutes; in other embodiments, 16-240 minutes; in other embodiments, greater than 240 minutes.
Different plugs may have different preferable cover degradation periods. For example, a frac plug which is lower in a string may preferably have a cover with a relatively shorter duration before frac plugs which are higher in the string. A frac plug which is higher in a string and which will not be used until after a lower frac plug and which will be subject to more sand infiltration and sand friction due to pumping of fracing fluid past it to frac lower zones, may preferably have a cover longer period to degradation. Additionally, it may be preferable for a cover on a frac plug which is higher in a string to have a thicker or stronger covering for protection against sand infiltration and sand friction than a frac plug which is lower than the string. To help workers at the well site more easily discriminate between frac plugs with covers having different degradation times, different thicknesses and different strengths when adding them to the string, the different covers may have their different degradation times, thicknesses and strengths be a feature of or featured on the covers, such as different covers being comprised of differently colored materials, having different stripes or different markings and the like.
An assembly is disclosed, in some embodiments, comprising a downhole tool whose outer surface is at least partially covered with a shrink wrap sleeve, in some embodiments, a heat shrink sleeve. In some embodiments, the shrink wrap may be a heat shrink sleeve or tubing, heat shrink sheet or heat shrink tape. In other embodiments, the wrap is an elastic sheet or film which wraps around the tool and is elastically held about the tool without the use of heat.
In some embodiments, a tool and wrap assembly is created when the unshrunk wrap is applied to at least partly cover the assembled tool and then heat is applied to shrink the wrap, so the wrap contacts and snuggly conforms to the outer surface of the assembled tool.
In some embodiments, a wrap is comprised of a material that will degrade in a downhole fluid. In some embodiments, the downhole tool is a settable downhole tool for use in isolating a portion of a wellbore, such as during completion and refracing operations. In some embodiments, all or part of the elements of the assembled downhole tool are degradable. In some embodiments, some or all of the elements comprising the assembled downhole tool are made of a polymer acid such as polyglycolic acid or polylactic acid, including Kuredux polyglycolic acid available from Kureha or its equivalent or a hydraulically degradable polymer degradable in a downhole fluid. In some embodiments, some or all of the elements of the tool are degradable metal, such as degradable magnesium or aluminum or alloys thereof. In some embodiments of the elements, the tool may be a composite or a resin or any other material. In some embodiments, the cover is comprised of a polymer acid, polylactic acid or polyglycolic acid and is degradable in downhole fluids. Applicant's wrap may be comprised and configured to slow or delay the degradation time of degradable elements of an at least partially degradable downhole tool for a predetermined time.
Labels made of any materials may be used with the wrap. The labels may include polylactic acid shrink labels, which are biodegradable. A biodegradable film that is heat shrinkable may be used as a wrap, bag or sleeve, such as a heat shrinkable film with a layered structure of lactic acid polymer/glycolic acid or a polymer/succinic acid-based polyester. One biodegradable heat shrinkable multilayer film that may be used is Krehalon® brand multilayer film from Kureha.
In some embodiments, the wrap has indicia on it which is visible from the outside such as instructions, marketing information and/or trademark information on an outer or inner surface thereof. In some embodiments, the wrap is clear, partially clear, or opaque. The color of the cover may be varied to identify the tools' seller or convey information about the tool, such as its type, rating, strength, etc. The cover material may have colored strips and dots of varying sizes, shapes and colors to convey information about the wrapped tool. Heat shrink wrap material can be made in a number of dimensions from thin walled flexible sheets to rigid heavy wall tubing.
Sand often accumulates on the bottom of the casing of a well's horizontal leg. The entire wellbore has sand and it typically falls out of the downhole fluid, ultimately being deposited in the bottom of the horizontal legs. The accumulated sand on the bottom of horizontal legs creates destructive abrasion and friction upon downhole tools as they are forced through the sand filled horizontal leg for completion and recompletion operations. In an embodiment, the covering is adapted to protect the tool from destructive sand friction as the tool slides through sand on the bottom of the wells horizontal leg. The wrap is adapted to make the covered tool smooth and strong enough to enable the covered tool to more easily slide through sand on the bottom of a horizontal leg of the well, namely, the cover, in some embodiments, may be longitudinally long enough to cover the tool's radially protruding portions, namely, upper and lower rings, upper and lower slips, upper and lower cones, and seal, and provide, in some embodiments, a smooth covered tool outer surface, and the cover is, in some embodiments, at least 2.0 mil thick for providing resistance against sand abrasion as the covered tool is run in through the horizontal leg. The smooth covering reduces both rotary friction and longitudinal friction of the tool in the casing. Reduced friction, particularly in a long horizontal leg, provides multiple benefits during completion and recompletion of longitudinal legs.
To provide longitudinal smoothness to best reduce longitudinal friction and help avoid inadvertent preset during run in, in some embodiments, the wrap does not tightly cling to the entire tool outer surface, but rather comprises a smoother outer covering about the tool's radially irregular surface comprised of its rings, slips, cones and elastomeric seal having different radial dimensions. The wrap may, for example, cling to the outer radial edges of rings and slips without extending further inward to inner radial surfaces of the tool. In an embodiment, the protective wrap is attached to at least some larger radial outer surfaces of the slip or slips and cone or cones and is not attached to some smaller radial outer surfaces of the slip or slips and cone or cones, and the protective wrap provides a covered tool outer surface which is smoother than a similar tool without the wrap. A tool with this type of covering is capable of sliding through a horizontal leg of the well having debris on the bottom of the horizontal leg with less friction through debris and thus horizontal force than a similar tool without such a smooth wrap.
Adapting the covering to survive casing caused and sand caused friction, abrasion and tearing requires selection of appropriate covering materials and covering thicknesses. In an embodiment, the covering is between 0.5 to 7 mil thick, in another between 1.5 to 5 mil, and in another between 2 to 3.5 mil thick. Preferable thickness may be a function of anticipated sand friction and erosion on the frac plugs, sand infiltration of the frac plugs, duration between insertion of the frac plug into the downhole fluid and the setting tool setting, sharpness of the slips inserts and withers, manufacturing limitations and conveniences, and other considerations. Protection against abrasion on a tool caused by sliding on the bottom of horizontal leg or by sand in the bottom of horizontal leg when the tool is to be moved through a horizontal leg, and reduction of friction when a tool is to be moved through a horizontal leg having sand or other debris on the bottom of the leg is somewhat obtainable by using a thicker covering. To protect against abrasion and friction a covering may be 5 mil, or 4 mil or 3 mil thick, as the abrasion protection and friction reduction circumstances may require, the more hostile the environment, the thicker the desirable covering. To applicant's knowledge, selecting and using downhole tool coverings with different thicknesses which are most appropriate for different downhole tool conditions and functions is not known in the industry. Such a covering may help protect the tool from sand friction due to the tool sliding through sand on the bottom of the horizontal leg and from sand infiltration during fracing of other zones.
In an embodiment and method of use of the coverings, after the first stage of a zone has been fraced at the bottom of the well, sand will typically be present in the well bore. Some operators may try to flush sand out of the wellbore, but current horizontal well practice causes laterals and horizontal legs to be extended further and further out. Longer horizontal legs make the effect of gravity pulling the string and plug down onto the casing greater. This creates more friction between the plug and the casing. Additionally, when the casing has debris in it, radially extending outward portions of a plug will pick up and be held back by the casing's debris. Additionally, to speed completion, some operators may run bottom hole assemblies/frac plugs into the wellbore with more speed than was typical in years' past. However, coil tubing can only push a string so fast on its own power, so to help overcome the friction caused by the string and bottom hole assembly dragging along the bottom of the casing of the horizontal leg as described above, some operators may pump fluid down bore hole while running the bottom hole assemblies/frac plugs down hole. This pumped down fluid can and does move past the bottom hole assembly at a rate faster than coil tubing can push. However, the fluid sometimes bypasses the frac plug may sometimes catch the rear facing rubber elements of the frac plug, causing an umbrella effect which can potentially deploy the frac plug's basketing system into its supporting cone and sometimes preset the frac plug's bottom slips. Preset BHA's/frac plugs can cost an operator hundreds of thousands or millions of dollars in unnecessary expenses. In an embodiment, the described protective sleeves militate against and sometimes entirely prevent these problems. Further, thicker and stronger sleeves provide more protection against destructive frac plug/casing friction which may damage the frac plug and which may cause it to preset and provides protection against the bypassing pumped down downhole fluid catching the rear facing rubber elements of the frac plug and causing an umbrella effect and sometimes pre-setting the frac plug's bottom slips.
Coverings of between 1 mil and 10 mil are functional for the described purposes, and in an embodiment, the coverings are about 2 mil, or about 0.002 inches, thick. However, in other embodiments and methods of manufacturing, other embodiments, including those intended to be used in far laterals as described above and to be used to militate against these above problems, the coverings or sleeves may be stacked during manufacturing of the sleeve and/or during the shrinking process about the frac plug, to provide a final thicker sleeve about the frac plug, which may be about 4 mil to about 8 mil thick, and preferably about 6 mil thick. In addition to stacking thinner sleeves to create a thicker sleeve, thicker sleeves can be used as a precursor material. Thicker sleeves additionally help reduce the biting effect of the frac plugs slip's buttons on the casing wall as the plug is pushed or pulled on the bottom of the casing. Thicker coverings are not limited to use in far laterals, but may also be useful in other downhole situations.
Heat shrink material is rated by its expansion ratio, a comparison of differences in expansion and recovery rates. Heat shrink tubing may be semi-rigid or rigid shrinkable plastic tubing. In some embodiments, it may be of a type that has heretofore been used in insulating wires and providing environmental protection for electrical conductors' joints and terminals. In some embodiments, heat shrink tubing may be made of nylon or polyolefin which shrinks radially (but not longitudinally) when heated, to between ½ and 1/16 of its initial preheated diameter for cylinder with a radius of between three and seven inches. In some embodiments, the wraps can shrink to half of their original size.
Heat shrink or shrink film may be made of thin sheets of polymer plastic film. When heat is applied, it shrinks tightly over the downhole tool. Heat may be applied with a handheld heat gun, or the tool on which the film is wrapped may be passed through a heat tunnel, conveyor, etc. In one embodiment, the shrink film is polyolefin. Shrink film can shrink in one direction (unidirectional) or bidirectionally. Shrink film may be applied over or around tool. It may be applied from flat roll stock or as a sleeve. Heat sealing may be used to tack it together. Centerfold film may be supplied on a roll with the plastic folded in half—the tool is placed in the center portion and the remaining three edges are sealed to form a bag. The tool may be placed in the bag. Preformed shrink bags or sleeves may be used with one end or both ends open, with the tool placed in the bag or sleeve, which is sealed and then heat shrunk.
In some embodiments, after the cover material is placed about the tool, the wrap is shrunk about the tool to tightly conform the material to the irregular shape of the tool, including its slips, cones and elastomeric seal, and particularly about the slip's sharp inserts and withers. This may require the use of a unidirectionally shrinkable material which shrinks radially about the radial tool and does not shrink appreciably longitudinally along the tool. Longitudinal shrinkage of the cover may cause the cover to tear on the slip's sharp inserts and withers and upon the tools of their irregular shapes.
Non-heat shrink plastic tubes may be used to protect the assembled downhole tools. Stretchable cling wrap, degradable or non-degradable may be used to cover or partly cover the downhole tool.
Applicant discloses a transport container for shipping multiple cylindrical downhole tools, each having a cylinder length and a cylinder diameter. The container may comprise: a rectangular body having sidewalls, a bottom wall, and an open top defined by a perimeter. A lid is configured to fit the open top and removably engage at least part of the perimeter when the lid is engaged. The container has an enclosed volume. A rack is configured to fit within the enclosed volume. The rack may have a top plate and a spaced apart bottom plate, the top plate and bottom plate configured with multiple spaced apart hole pairs. The rack's holes have an inner diameter greater than the target downhole tool's outer diameter and the plates are spaced apart a distance less than the cylinder length and at least far enough apart to keep adjacent tools in the container from contacting each other. The rack may be located and configured to hold the downhole tools in a vertical alignment spaced apart from one another when the rectangular body is resting on a horizontal support surface and to key at least a portion of the downhole tools in the rack extending above an upper surface of the top plate.
The shrink wrapped tool may be delivered on a pallet load of frac plugs to the well site or in a container, typically a pallet-sized, returnable plastic transport container. The individual frac plugs may each be in an individual degradable plastic shrink wrap. The smooth shrink wrap plastic covering about tool irregular parts and, in some embodiments, edges will lessen run-in plug/casing insertion interaction. Use of a shrink wrap about the downhole tools protects moisture sensitive degradable downhole tools, such as degradable frac plugs, from atmospheric and other moisture, eliminates the many cardboard containers which often currently litter well sites, provides cost savings, provides degradable plugs with a longer warehouse and well site shelf life, and makes well into operations more environmentally friendly.
A method for making a tool and wrap assembly comprising a downhole tool having a heat shrink wrap, the assembly is disclosed in which at least a portion of an exterior of an assembled settable downhole tool is covered or wrapped, at least partially, in a heat shrink wrap, to which assembly heat, typically conductive, convective or radiant, is applied creating a shrink wrapped tool.
In their pre-shrunk configuration, shrink wrap sleeves 16 may be open at both ends, and configured to receive the downhole tool therein. The sleeve may be a bag open at one end and closed at the other end. The coverings may be clear and/or include multiple colors, graphics, indicia, and branding. The coverings offer tool tamper protection and evidence of tool tampering, especially when a full body shrink sleeve is used. Some heat shrink products include a vapor corrosion inhibitor (VCI). In some embodiments, the covering is breathable. A sleeve (tube) open at both ends may be subsequently closed at one or both ends following insertion of the tool into the sleeve. A non-rigid sleeve closed at one end (bag) may be closed or party closed at the other following insertion of the assembled tool.
In one embodiment, custom printed shrink sleeves made of degradable polyglycolic or polylactic acid are provided. The sleeves are slid over the downhole tool and, in some embodiments; hot air is applied, in some embodiments, with a hoop shaped heating apparatus or any other suitable device. This causes the wrap to shrink and conform to the plug in a uniform manner. The sleeve, bag or sheet may be printed with a company logo, running instructions, etc. The rate of dissolution of wrap 14 can be selected in part by the number of sleeves used (multiple plies on a single assembled tool), the thickness of an individual sleeve (thicker slows degradation), selection of sleeve materials, or other adjustments to the sleeve.
In one embodiment, sheet 18 is Biolefin 2.0, a biodegradable shrink film about 0.6 mil thick, which may be perforated or not. It is a food grade, acid-free, oxo-biodegradable shrink film. It shrinks clear and is available in 14 to 18″ widths. See www.nationalshrinkwrap.com. Multiple lies (wraps) may be used on one tool.
Another heat shrink sleeve, open at both ends, suitable to wrap downhole tools, in some cases downhole tools with some or all of their elements being degradable in a downhole fluid, is Earth First® PLA. This heat shrink sleeve may be provided and be useful within a range of about 1.2 mil to 6.8 mil, and in some embodiments about 2.8 mil. This heat shrink sleeve is compostable according to ASTM D6400. It is made from non-petroleum material such as renewable resources, for example, cane sugar, tapioca roots and corn. Unlike some other shrink films, this product can be stored at up to 100° F. without instability. It is a polylactic acid film. These films may be shrunk in many types of commercially available heat shrink tunnels including: infrared, hot air, steam flow or any combination thereof. They provide full body or partial body shrinkage in unidirectional or bidirectional. In some embodiments, its ultimate tensile strength is 48 MPA (machine direction) and 130 MPA (transverse direction), ASTM D882. Westrock® provides shrink sleeve packaging for partial or full coverage, including PLA sleeves that are biodegradable and compostable.
Regardless of the heat shrink wrap used, in some embodiments, heat shrink containers or wraps may be between ⅛ and 2 inches greater diameter in their preshrunk configuration than the tool's diameter. More preferably, the preshrunk heat shrink containers or wraps may be between ½ inch and 1½ inches greater in diameter than the tool's diameter. Most preferably, the preshrunk heat shrink containers or wraps may be between three quarters of an inch and 1 inch greater in diameter than the tool's diameter. For example, to contain or wrap a 4 inch diameter downhole tool, a container or wrap that is about 5 to 6 inches in diameter may be used, or containers or wraps otherwise sized as described may be used.
Polyvinyl chloride (PVC) may be used for low cost sleeves. It provides a gloss finish and up to 65% shrinkage. Polyethylene terephthalate films may also be used and can shrink up to 75% of their original size and may encompass even the most intricate shapes. It has good product resistance and high clarity. OPS film is a high clarity, petroleum based shrink film, which shrinks up to 70% of its original size. Polylactic acid (PLA) film is a high clarity, bio-based film made from corn. It may shrink up to 75% of its original size and is 100% compostable, conforming to ASTM 6400. It may be used in conjunction with PLA labels. Some films can combine the use of the PLA biopolymer with OPS and/or PETG. These hybrid films can be designed for varying degrees of degradability in a downhole fluid. In some embodiments, the polylactic acid film will heat shrink between about 157-276 gauge (ASTM D 4321) and may, in some embodiments, have an ultimate tensile strength between 7000 psi-19,000 psi (ASTM D 882) shrinkage may be 5 and 75% at 85° C. (unrestrained 10 seconds circulating water bath).
Heat shrink wrap choices may be made based on the percentage of shrink needed, desired finish (gloss/matte), user requirements, degradation considerations, and sustainability. Shrink percentages may range from 5 to 90% of original size. A cylindrical downhole tool, may be 2½ to 14 inches in diameter and 16 to 46 inches in length.
In some embodiments, the downhole tool is a conventional plug such as a zonal isolation tool, bridge plug, packer or the like. The disclosed plastic tube, film, wrap or sleeve is placed about the tool and is sealed about the tool. This may include shrinking the wrap about the tool, or tightly wrapping of the wrap about the tool. Tool instructions, tool identification, RFID Chip tracking label, seller identification and the like may be included on a label located between the tool and the wrap and visually readable through the wrap. The information on the protective cover may include a scannable code, QR or bar code and may allow the tool manufacturer to go paperless—not needing to include paper instructions. Information may include instructions, tool data, and serial number. Such a label or information may be placed or printed on the outside or inside of the wrap. Such a wrap protects the tool from moisture, corrosion and abuse prior to the tool being attached to the drill string and run down hole. If the tool is degradable by moisture, such as a tool having elements made of degradable PGA, PLA, magnesium, aluminum (or their alloys) or other degradable materials, the wrap protects the tool from premature corrosion or degradation due to atmospheric humidity. A degradable setting tool has one or more structural elements which, when they degrade, cause the tool to release from the casing. Typical structural elements are the mandrel, slips or cone.
In some embodiments, the shrink wrap protects handlers and workers from the tool's sharp edges, such as the wickers or inserts of slips or tool threads. In
In some embodiments, the wrap is not a heat shrink wrap. A printable and degradable wrap is EcoSol® a water soluble packaging solution from Cortex Corporation. EcoSol is a polyvinyl alcohol (PVOH) wrap which after a few minutes submerged in water at an elevated temperature leaves a harmless, non-toxic, aqueous solution of polyvinyl alcohol. The mechanical properties of EcoSol® packaging conform to ASTM D 882-02 for breaking factor, tensile strength of break, elongation and strength. Its tear strength is tested according to ASTM D 1922-06a and dart drop impact resistant for ASTM D 1709-04. EcoSol is not heat shrinkable. It may be wrapped tightly around the tool or formed into a bag which will snugly receive the tool. While some of the foregoing embodiments discuss heat shrinkable materials, some of which are degradable, in some other embodiments, the covering may be a water soluble, biodegradable film, wrap or package, such as one made of polyvinyl alcohol (PVOH) which is chemically resistant to mineral, vegetable, and animal oils as well as certain hydrocarbons. PODS (degradable detergent capsules) are sometimes comprised of PVOH. They will degrade in an aqueous solution and may or may not be heat shrinkable. The time required for dissolution varies depending upon the thickness of the film and the temperature of the water. In one embodiment, an EcoSol 1.5 mil thick at 68° F. begins to dissolve within thirty seconds and is fully dissolved in five minutes of contact with an aqueous solution at 72°. Thicker film takes longer to dissolve. In some embodiments, the shrinkable or non-shrinkable film is selected to dissolve between 2 to 240 minutes after immersion in an aqueous solution temperature greater than 20° C. or up to 150° C.
Like heat shrinkable wrap, a biodegradable non-heat shrinkable film is not a coating on the tool per se, but is a bag, sack or wrap for enclosing an assembled tool. However, when sealed, or partially sealed, and snug to the surface of the tool, it provides a delay in degradation of the tool, and also provides protection while the tool is being handled, prior to and after insertion in the well hole casing
Another product, heat shrinkable, is Cortex MilCorr® VpCI shrink film. It provides UV protection for outdoor storage and protects from corrosion multiple metals including steel, aluminum, brass, copper, iron and the like. It may be used to prevent rust on iron and steel parts of the tool. It will protect against salt air and humid environments, moisture, aggressive industrial atmosphere (it includes a phase corrosion inhibitor) and dissimilar metal corrosion. The corrosion inhibitor is vaporized and condensed on all metal surfaces within the enclosed space and diffused to every area of the enclosed tool, protecting the exterior as well as void spaces in recessed areas.
Another non-heat shrinkable plastic sheet embodiment is use of a stretchable cling wrap 40 to at least partially cover the assembled tool, which cling wrap may be clear and degradable. Cling wrap is typically used for sealing food items in containers. Cling wrap can be used in a variety of thicknesses including 0.5 mil. Little stretch is needed to wrap it around the typically cylindrical tool several times. It clings to the tool's edges and remains tight over the tool, even without adhesive. One biodegradable cling wrap is known as BioBag®. In
In some embodiments, a wrap, bag, sleeve or sheet may be starch-based films in bags (typically called a “BioBag”) made of starch of fiber typically corn, soy or potatoes. Oxo-degradable bags are different from BioBags. They are additive-based biodegradable film/bags which include additives to the resin to control degradation upon exposure to different conditions. Oxo-degradable films degrade by oxidation, hastened by chemical additives. Shrink wrap may be Oxo-degradable.
Other types of degradable plastics may be used, such as additive-based wraps, including hydro-biodegradable plastics which degrade by hydrolysis and thermal-based biodegradable plastic which degrades with exposure to heat. Degradation rates for these wraps or bags may be controlled if the environment, such as downhole fluid, is generally known, for example, heat conditions and chemical nature of the fluid (for example, brine).
In another embodiment, a coating is directly applied to the tool, either to the assembled tool or to one or more of the tool's parts prior to assembly. For example, a degradable polymer portion of a downhole tool may be comprised to begin degrading immediately upon contact with the well's downhole fluid. For some well sites and some operations, degradation of the degradable tool immediately upon it entering the wellbore may be desirable. For other well sites and other operations, however, such degradation beginning immediately may be undesirable. In the latter circumstance, either the assembled tool or parts of the tool prior to assembly have a coating applied which coating separates the degradable polymer parts of the tool from the degrading downhole fluid. Application of the coating may be by spraying the tool or parts, brushing the coating on the tool or parts or otherwise. For some applications, multiple layers of coatings may be applied to the tool or parts.
For example, if a particular tool part is comprised of a degradable polymer, such as a degradable PLA or PGA, which will begin hydrolytic degradation immediately upon being immersed in the aqueous downhole fluid, then a water impermeable coating on that part will delay the onset of that part's degradation. A part or tool with a water impermeable coating will initially separate the water degradable part from the aqueous downhole fluid when the downhole tool enters the downhole fluid. However, as the tool is lowered into the wellbore it will rub and bump against the casing, the rubbing and bumping scratching through the coating. The scratched areas of the tool will then be in direct contact with the aqueous downhole fluid. The parts of the tool opened to contact with the downhole fluid by the scratches will then begin to degrade.
This use of a water impermeable coating to delay the initiation of water degradable parts in the downhole tool, and then use of casing/downhole tool scratches through the coating to initiate degradation provides an additional element of control to the tool's degradation. A degradable tool which, without the coating would degrade too quickly, becoming too soft too quickly for reliable use in fracing operations, by use of a described coating, can have its degradation delayed so the tool is more useful in the particular target fracing operation. Thereafter, the tool degrades, degradation beginning at the places where the coating has been scratched or otherwise abraded off of the tool.
This ability to delay onset of degradation of the tool permits use of degradable materials in the tool which are more rapidly degradable than would be possible without use of the coating. Use of a described coating protecting a degradable tool permits use of degradable tool materials that will more quickly degrade and will more quickly open the wellbore after the tool's intended use in the fracing operation. In some embodiments, such a tool may produce an unobstructed borehole more quickly than a similar tool without such a coating and which is comprised of a degradable material which degrades more slowly due to the need for the similar tool to not soften too much prior to the fracing operation
Not all possible impermeable coatings are as useful for the described purpose as others. For example, many paints or coatings will not sufficiently adhere to a tool made of degradable polymer such as PGA and PLA. Normal wear and tear during transportation, handling, making up the drill pipe etc. may prematurely remove such coatings. In addition to sufficient adherence to the tool being a requirement, in some embodiments, the coating must be hard enough and thick enough to not so completely abrade off of the tool during initial insertion into the borehole that too much downhole fluid/degradable tool contact occurs immediately upon the tool entering the borehole. On the other hand, the coating must be sufficiently frangible and abradable that it will incur sufficient through coating scratches, cuts and abrasions and permit sufficient downhole fluid/degradable tool contact as the tool approaches its targeted area in the cased borehole or is used for the tool's intended functions. For example, it has been found that Krylon primer paint adheres to degradable polymers sufficiently to decrease degradation of the degradable tool in the downhole fluid, but also scratches and abrades sufficiently as it approaches its target fracing operation downhole for it to be a useful coating for the described purposes. Other hard tough coatings, such as ceramics coatings, are useful for this purpose.
As described above, some parts of a degradable tool may be more degradable than other parts. Some parts of a downhole tool have different structural requirements. Accordingly, some parts of a degradable downhole tool may have a cover or coating applied, while other parts of the tool may not. In other embodiments, different parts may have a different cover or coating. In other embodiments, different parts may have coatings with different thicknesses. Parts that are coated, choice of coatings, thickness of coatings and the like may be adjusted to provide a degradable tool which retains sufficient structural strength at downhole operation point to complete its intended operation, and for the tool to then quickly degrade, release from the casing, and thereafter substantially completely degrade.
As can be seen in
The shipping system for the tools may include: transport container and protective wrap, and/or outer bag for the tool or tool and wrap combination. All of the foregoing may be “green” in that all of these may be comprised of biodegradable materials. Moreover, it has been seen that the shipping system may be “paperless,” thereby further reducing the carbon footprint.
This application discloses and assembly for use in a cased hydrocarbon well, the assembly comprising: a settable downhole tool having multiple elements entrained upon a mandrel thereof, the downhole tool having an outer surface, the tool in the preset configuration; and, a degradable protective wrap at least partly covering the outer surface of the tool in a snug fashion. In some embodiments the wrap is heat shrink wrap, the protective cover further includes indicia on an outer surface thereof, at least some of the multiple elements of the downhole tool are degradable in a downhole fluid, the protective wrap is compostable, a label is included between the protective wrap and the outer surface of the tool, at least part of the protective wrap is clear, a label on an outer surface of the protective wrap, the label is biodegradable, the protective wrap is comprised of a polymer acid film, the polymer acid film is comprised of polyglycolic acid or polylactic acid, the polymer acid film is degradable, a sealed outer wrap adapted to sealingly enclose the settable downhole tool with the protect wrap thereon.
This application discloses method of making a tool and wrap assembly, the method comprising: providing a downhole tool; placing a protective wrap about the tool, the wrap being a shrinkable plastic wrap comprised and configured to when shrunk around the tool; shrinking the wrap material about the tool; the shrunk wrap encasing the tool and comprised so the wrap helps protect the tool from atmospheric humidity, and the wrap does not interfere with the tool's use downhole; wherein the protective wrap is degradable in a downhole fluid.
This application discloses a tool and cover assembly, the assembly comprising: a downhole tool; and a cover located closely about the tool, the cover not being laminated to the tool or an integral layer of any part of the tool, the cover comprised and configured to encompass at least part of an outer surface of the tool, and protect the tool from atmospheric humidity, and to not interfere with the tool's intended use downhole; and wherein the cover is comprised of one of the following: fluorinated ethylene propylene (PEP), polyolefin, PVC tubes, polyvinylidene fluoride (PVDF), silicone rubber, PLA, PGA, PVOH, PTFE (fluoropolymer) or Viton and is between 0.5 to 8 mil in thickness. This application discloses an assembly for use downhole in a hydrocarbon well, the assembly comprising: a downhole tool; and a protective cover located closely about the tool, the cover not being laminated to the tool or an integral layer of any part of the tool, the cover comprised and configured to encompass the tool, and to protect the tool from atmospheric humidity and other conditions, and which does not interfere with the tool's intended use downhole; and wherein the protective cover is degradable in an aqueous downhole fluid.
This application discloses a method of working on a hydrocarbon well having a vertical leg and a horizontal leg extending into a hydrocarbon bearing formation, the horizontal leg including a heel and a toe, the well having casing in the horizontal leg with an at least a 4½ inch outer diameter (O.D.) and not more than a 6½ inch outer diameter (O.D.), the casing having an inner diameter (I.D.) in the horizontal leg, and the casing having a series of casing patches reducing the ID of the casing in the horizontal leg, the method comprising: providing at least five retracted settable downhole tools, each having a protective cover, selecting five such retracted tools, each retracted tool narrow enough to be run through and past a 0.125 inch thick casing patch in the horizontal leg, and each tool having slips which are expandable enough so after the tool passes through the casing patch the slips can be expanded to an expanded slip configuration having an O.D. within the range of a radial inner limit of a 15% expansion of the retracted tool's O.D. and the inner diameter the casing and the expanded tool's slips are capable of setting against the casing of the horizontal leg and holding the tool to the casing during refracing to isolate an upper zone in the horizontal leg above the tool from a lower zone below the tool; the method further comprising: the steps of running the five tools with the protective cover thereon into the well and immersing the tools in a wellbore fluid in the well, produced from formation flow in the well having a pH less than 7, running the tools past the casing patch, setting the tools within the casing, and using the tools in isolating and refracing zones in the horizontal leg past one or more of the casing patches; the first tool being run in and set and used in isolating and refracing, then the second tool being run in and set above the first tool and used in isolating and refracing, then the third tool being run in and set above the second tool and used in isolating and refracing, then the fourth tool being run in and set above the third tool and used in isolating and refracing, then the fifth tool being run in and set above the fourth tool and used in isolating and refracing; waiting until after the tools are immersed in the downhole fluid in the well for the tools to degrade in the wellbore fluid enough to permit production of hydrocarbons from the well; and producing hydrocarbons from the horizontal leg after the tools are immersed in the downhole fluid in the well, without milling out or retrieving the five tools, the downhole fluid has a pH of 7 or less, or greater than 7.
This application discloses a transport container for shipping multiple cylindrical downhole tools, each having a cylinder length and a cylinder diameter, the container comprising: a rectangular body having sidewalls, a bottom wall, and an open top side defined by a perimeter; a lid, configured to fit within the open top side and to removably engage at least part of the perimeter when the lid is engaged, the container having an enclosed volume; and a rack located within the container, the rack configured to fit within the container's enclosed volume, the rack having a top plate and a spaced apart bottom plate, the top plate and bottom plate configured with multiple spaced apart hole pairs; wherein the holes have an inner diameter greater than the downhole tool's diameters, and the plates are spaced apart a distance less than the length of the downhole tools, the rack configured to hold the downhole tools in vertical alignment and the downhole tools spaced apart when the rectangular body is resting on a support surface, and wherein at least a portion of the each of the downhole tools extend above an upper surface of the top plate, wherein the lid or the body includes weather-stripping and the rack includes locators.
This application discloses a method of shipping cylindrical downhole tools including: providing a container; placing cylindrical downhole tools in the container; delivering the container containing the downhole tools to a well site; removing the downhole tools from the container for use at the well site; removing the container from the well site; and reusing the container by again placing tools in the container, delivering the loaded container to a well site and removing the container from a well site.
This application discloses fracing in oil and gas well are well known in the art. These methods use settable downhole tools, in some cases bridge or ball drop plugs. Tools used in completion and fracing may be degradable in a downhole fluid or may be nondegradable (millable). Applicant's protective wrap may be used on either degradable or nondegradable tools when they are run in and set downhole. The embodiments disclosed herein are modifications of known methods of completing and refracing oil and gas wells by using tool and wrap assemblies and transporting and using them as disclosed herein.
This application discloses a degradable assembly for use in a cased hydrocarbon well comprising: a settable downhole tool, the tool having a mandrel, a slip, and a cone; a protective coating for use about a settable downhole tool having a mandrel, slip or slips and cone or cones, comprising: the coating is degradable in the well's downhole fluid and covering an outer surface of at least the slip or slips and cone or cones, the coating adapted to degrade in a well's acidic aqueous downhole fluid and not interfere with running the tool into the well or interfere with the tool setting or sealing against the casing, the coated tool is adapted to be run into the well's casing, and then the coating to at least partially degrade in the well's downhole fluid, and then the tool to be set into and sealed against the casing; and, a moisture impermeable outer shell, the shell entirely enclosing the covered tool, and adapted to be easily removable from the covered tool prior to inserting the covered tool into the casing.
This application discloses a method of making a tool and wrap assembly for use at a cased well having acidic aqueous downhole fluid, comprising: providing a settable downhole tool, the tool having a mandrel, a slip and a cone; selecting a wrap material which is hydrolytically degradable in acidic aqueous downhole fluid, and which when shrunk about the tool, will provide a tool and wrap combination insertable within a casing and will provide a wrap about the tool which will not interfere with setting or sealing the tool against the casing; placing the wrap material about the outer surfaces of at least the slip and the cone; shrinking the wrap material about the tool so the wrap material becomes a shrunk wrap material about an outer surface of the slip and the cone, and provides a protective cover about the slip and the cone; and placing a moisture impermeable outer shell about the tool and wrap combination, the shell entirely enclosing the tool and wrap combination, and the shell being easily removable from the tool and wrap combination prior to insertion of the tool and wrap combination into the casing, providing a tool structural element which is degradable in acidic neutral or basic aqueous downhole fluids, the degradable structural element being at least one of a mandrel, cone or slip; wherein the resulting tool and wrap are comprised so the tool and wrap will degrade in the well's aqueous downhole fluids, and degradation of the tool's degradable structural element will release the tool from the casing, wherein the wrap material of the selecting step is a heat shrinkable wrap material, wherein the placing step includes placing the heat shrinkable wrap material about the entire outer surface of the tool's slips and cones; moving the wrapped tool through a thermal tunnel; using the thermal tunnel to apply enough heat to the wrap material as the wrap tool moves through the thermal tunnel to shrink the wrap material about the tool so the wrap material is secured to the tool and the wrap material provides a covered tool outer surface which is smooth enough to enable the covered tool to slide through sand on the bottom of a horizontal leg of the well with less friction than a similar tool without the wrap, namely, the wrap is longitudinally long enough to entirely cover the tool's slips and cones, and the wrap provides a covered tool outer surface which is smoother than a similar tool without the wrap, wherein the selecting step includes the step of selecting a wrap material between 0.5 to 7 mil thick, wherein the selecting step includes the step of selecting a wrap material between 1.5 to 5 mil thick, wherein the selecting step includes the step of selecting a wrap material between 0.2 to 3.5 mil thick, wherein the selecting step includes the step of: selecting a wrap material which will shrink unidirectionally; wherein the placing step includes applying the unidirectional wrap material about the tool so when the material is shrunk, it primarily shrinks radially about the tool and not longitudinally along the tool; and wherein the shrinking step includes shrinking the wrap material about the tool to produce a wrap covering at least the tool's cone and slip without the shrinking causing inserts or withers on the slip to penetrate the wrap material, wherein the selecting step includes selecting a wrap is comprised of a preformed tube having an inner diameter which is less than 1.5 inches larger than the outer diameter of the tool, the tube having a first end and a second end, both first and second ends being open, wherein the selecting step includes selecting a comprised of a preformed tube having an inner diameter which is less than one inch larger than the outer diameter of the tool, the tube having a first end and a second end, the first end being open and the second end being closed, wherein the selecting step includes selecting a comprised of a preformed bag having an inner diameter which is less than one half inch larger than the outer diameter of the tool, the tube having a first end and a second end, the first end being open and the second end being closed, wherein the selecting step includes selecting a wrap material which is primarily unidirectionally shrinkable and arranging the wrap material about the tool so wrap shrinkage primarily reduces the wrap's radius about the tool and does not primarily reduce the wrap's length along the tool, and so the wrap material's shrinkage does not cause the wrap to tear at the slip's inserts or withers.
This application discloses a method of making an assembly for use at a cased hydrocarbon well, the method comprising: providing a settable downhole tool, the tool having at least a mandrel, a slip, and a cone; providing a protective coating which is hydrolytically degradable in an acidic aqueous downhole fluid; covering outer surfaces of at least the slip and the cone with the protective coating, the coated tool adapted to be insertable within the well's casing, and the wrap adapted to degrade in the well's acidic, basic or neutral downhole fluid and not interfere with the tool setting or sealing against the casing; and, providing a moisture impermeable outer shell, the shell adapted to be easily removable from about the covered tool prior to inserting the covered tool into the casing.
This application discloses a transport container for shipping multiple cylindrical downhole tools, each tool having a cylinder length and a cylinder diameter, the container comprising: a container having sidewalls, a bottom wall, and an open top side defined by a perimeter; a lid, configured to fit within the open top side and to removably engage at least part of the perimeter when the lid is engaged, the container having an enclosed volume; a rack located within the container, the rack configured to fit within the container's enclosed volume, the rack having a top plate and a spaced apart bottom plate, the top plate and bottom plate configured with multiple spaced apart hole pairs; each hole has an inner diameter greater than each tool's outer diameter; the top and bottom plates are spaced apart a distance less than the length of the shortest downhole tool; the holes are configured and located and the container is sized to hold the tools in static spaced apart horizontal and vertical positions and alignment relative to the other tools and to the container; at least a portion of the each of the tools extends above an upper surface of the top plate; the container has a lid which may be opened and closed for access to the tools within the container; and wherein the container is adapted to be sealed against entry of moisture from outside the container to inside the container when the lid is closed, the container is configured and comprised of materials strong enough so the container is capable of being used to transport downhole tools to a well site, retrieved multiple times from wells, and reused multiple times to transport downhole tools to wells; and the container is comprised of recyclable materials.
This application discloses a method of transporting multiple assemblies, the method comprising: providing a shipping container containing a rack, the rack having a top plate and a spaced apart bottom plate, the top plate and bottom plate configured with multiple spaced apart hole pairs; wherein each hole has an inner diameter greater than each covered tool assembly's outer diameter, and the top and bottom plates are spaced apart a distance less than the length of the shortest downhole tool, wherein the holes are configured and located to hold the covered tool assemblies in horizontal and vertical alignment, keeping the covered tool assemblies apart, and wherein at least a portion of the each of the covered tool assemblies extends above an upper surface of the top plate; placing multiple covered tool assemblies into the shipping container and delivering the shipping container with the multiple covered tool assemblies to the well; removing the multiple covered tool assemblies from the shipping container at the well; and reusing the container to contain and transport additional downhole tools to the same or other wells.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. On the contrary, various modifications of the disclosed embodiments will become apparent to those skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover such modifications, alternatives, and equivalents that fall within the true spirit and scope of the invention.
This application claims the benefit of, priority to, and incorporates herein by reference U.S. Provisional Application No. 62/635,713, filed Feb. 27, 2018 and U.S. Provisional Application No. 62/658,736, filed Apr. 17, 2018. U.S. patent application Ser. No. 15/355,346, filed Nov. 18, 2016, and Ser. No. 16/182,206, filed Nov. 6, 2018, are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62635713 | Feb 2018 | US | |
| 62658736 | Apr 2018 | US |
