Patent Publication Number: US-10787864-B1

Title: Web protectors for use in a downhole tool

Description:
FIELD 
     Embodiments usable within the scope of the present disclosure relate, generally, to apparatus, systems, and methods for protecting one or more components of a downhole tool during activation of the downhole tool. And more particularly, the embodiments relate to systems and methods for using a liner or a web protector to minimize, block, or prevent erosion of a pillar that is adjacent to an opening of the downhole tool. 
     BACKGROUND 
     Many wellbore operations necessitate deploying a downhole tool within a wellbore. Some operations may be accomplished through the use of tools employing brute-force methods such as explosive charges, drill bits, fluid pressurized at the surface of the wellbore, or other high-energy and high-impact methods. Other less-destructive operations may require downhole tools capable of performing precise or delicate jobs. For an increasing number of these operations, a non-explosive downhole tool is preferred. Non-explosive downhole tools include, for example, torches, perforators, setting tools, fracturing equipment, and the like (collectively referred to herein as downhole tools) that can be powered through the use of thermite fuel or fuel derived from a chemical reaction. 
     A need exists, in the oil and gas industry, for the ability to activate non-explosive downhole tools with a controlled expulsion of the molten fuel or chemical fuel, and to maintain accuracy of the sprayed (i.e., projected) molten fuel over multiple uses of the downhole tool. Non-explosive tools are powered by a reaction that is slower and more controlled than explosive-type downhole tools. This can allow for directed blasts of molten fuel forced through nozzles or openings. Over repeated uses, the openings can be worn out and can change shape, causing inaccurate flow during firing. In some embodiments, when the downhole tool wears out, the structural integrity of the downhole tool can be compromised. In such embodiments, the downhole tool may break apart during firing, causing more trouble and potentially additional time taking the remains of the downhole tool out of the wellbore. 
     Additionally or alternatively, a need exists to create a forceful blast or projection of the molten fuel or chemical fuel. Past examples of downhole tools utilizing thermite fuel or chemical fuel have been limited in the size and shape of the nozzles that may be used. The previous tools have used broader nozzles due to the lack of protection to the areas around the nozzles. The nozzles wear out causing a change in the flow of the molten fuel or chemical fuel, and in some instances could cause breakage or premature destruction of the downhole tool. 
     The present embodiments meet these needs. 
     SUMMARY 
     The disclosed embodiments include a downhole tool that is configured to be inserted into a wellbore, wherein the downhole tool comprises: a tool body comprising an external surface and an internal volume that can be configured to store a thermite fuel, wherein the thermite fuel is configured to ignite into a molten thermite fuel. The thermite fuel comprises a metal and an oxidizer that can oxidize the metal. The downhole tool further comprises an opening extending from the internal volume and through the external surface, wherein the opening can be configured to project (i.e., spray) the molten thermite fuel, and a pillar defining one side of the opening. The pillar can comprise an internal side that faces the internal volume, and an opening side that faces the opening. The downhole tool includes a web protector that can abut at least the internal side of the pillar to block the molten thermite fuel from impinging the internal side of the pillar. 
     In an embodiment, the web protector further abuts the opening side of the pillar to also block the molten thermite fuel from impinging the opening side of the pillar. 
     In an embodiment the downhole tool can comprise an additional opening, wherein the pillar further defines a side of the additional opening. The opening and the additional opening can be configured to project (i.e., spray) the molten thermite fuel in a pattern that severs a production tubing. In an embodiment, the opening and the additional opening together can extend around eighty percent (80%) to ninety-nine percent (99%) of a circumference of the downhole tool. 
     Embodiments of the downhole tool include a web protector that comprises polyether ether ketone, another polymer, a ceramic material, a graphite material, or combinations thereof. In an embodiment, the web protector can be attached to the pillar with a securing connector, wherein the securing connector can comprise a chemical adhesive, a magnet, a mechanical fastener, or combinations thereof. 
     In an embodiment, the downhole tool can comprise a liner that can be configured to line the internal volume. The liner can comprise a first material, and the web protector can comprise a second material that is different from the first material. In an embodiment, the web protector is the liner. 
     An embodiment of the downhole tool can include: an opening for projecting (i.e., spraying) molten thermite fuel, a pillar that defines one side of the opening, and a web protector that comprises a body that is made from a material that is heat resistant and erosion resistant to the molten thermite fuel. The body of the web protector can further include at least one side that is configured to abut a side of the pillar of the downhole tool to block the molten thermite fuel from impinging the side of the pillar. In an embodiment, two sides of the body of the web protector can abut two sides of the pillar. 
     The material of the web protector can comprise polyether ether ketone, another polymer, a ceramic material, a graphite material, or combinations thereof. In an embodiment, the web protector can further include a securing connector for attaching the web protector to the pillar, wherein the securing connector can comprise a chemical adhesive, a magnet, a mechanical fastener, or combinations thereof. In an embodiment, the non-explosive fuel comprises: a thermite, a thermite mixture, or a chemical. In an embodiment, the chemical is an acid, nitrogen fluoride, a nitrogen fluoride mixture, a nitrogen trifluoride, a bromine trifluoride, or a solid gas. 
     Embodiments of the present invention include a method of using a downhole tool within a wellbore, wherein the downhole tool includes a thermite fuel that can comprise a metal and an oxidizer that can oxidize the metal. The thermite fuel can be contained within an internal volume of the downhole tool. The downhole tool can further comprise an opening for projecting (i.e., spraying) molten thermite fuel and a pillar defining one side of the opening. The steps of the method comprise: attaching a web protector to the pillar of the downhole tool so that at least one side of the web protector abuts a side of the pillar, wherein the web protector comprises a material that is heat resistant and erosion resistant to the molten thermite fuel, and inserting the downhole tool into the wellbore. The steps of the method continue by activating the thermite fuel in the internal volume of the downhole tool to generate the molten thermite fuel, and projecting (i.e., spraying) the molten thermite fuel through the opening of the downhole tool, wherein the web protector blocks the molten thermite fuel from impinging the side of the pillar. 
     The steps of the method can further comprise retrieving the downhole tool from the wellbore, replacing the thermite fuel with a second thermite fuel, inserting the downhole tool into the wellbore a second time, activating the second thermite fuel to generate a second molten thermite fuel, and projecting (i.e., spraying) the second molten thermite fuel through the opening of the downhole tool. In an embodiment, the projecting (i.e., spraying) of the molten thermite fuel can sever a production tubing within the wellbore. 
     In an embodiment, the web protector can be attached to the pillar with at least one of a chemical, a magnetic, and a mechanical connection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of various embodiments usable within the scope of the present disclosure, presented below, reference is made to the accompanying drawings, in which: 
         FIG. 1  illustrates a cross-sectional schematic view of an embodiment of a system located in a possible operating environment. 
         FIG. 2  illustrates a cross-sectional schematic view of the downhole tool of  FIG. 1  firing on a target location. 
         FIG. 3  illustrates a side view of an embodiment of the downhole tool having a liner. 
         FIG. 4  illustrates a cross-sectional top view of the embodiment of the downhole tool illustrated in  FIG. 3 . 
         FIG. 5  illustrates a cross-sectional top view of an embodiment of the downhole tool having a web protector. 
         FIG. 6  illustrates a side view of the embodiment of the downhole tool illustrated in 
         FIG. 5 . 
         FIGS. 7A and 7B  illustrate a side view of an embodiment of the downhole tool having a web protector surrounding pillar connectors. 
         FIG. 8  illustrates a cross-sectional top view of the embodiment of the downhole tool illustrated in  FIGS. 7A and 7B . 
     
    
    
     One or more embodiments are described below with reference to the listed FIGS. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Before describing selected embodiments of the present disclosure in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, means of operation, structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention. 
     As well, it should be understood that the drawings are intended to illustrate and plainly disclose presently preferred embodiments to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views to facilitate understanding or explanation. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention. 
     Moreover, it will be understood that various directions such as “upper”, “lower”, “bottom”, “top”, “left”, “right”, “uphole”, “downhole”, and so forth are made only with respect to explanation in conjunction with the drawings, and that components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting. 
       FIG. 1  illustrates a cross-sectional schematic view of an embodiment of a system  10  of the present invention that is located in a possible operating environment. The system  10  may include a tubing string  12  and a downhole tool  14  that have been lowered into production tubing  16  and/or casing  18  within a wellbore  20 . The casing  18  may be cemented or otherwise set within the wellbore  20  to protect the wellbore and to support the surrounding rock structure and prevent a collapse. The wellbore  20  may be located in or through a production zone from which hydrocarbons or other fluid may be pumped out through the production tubing  16 . In some situations during the operation of the system  10 , the production tubing  16 , casing  18 , or other components within the wellbore  20  may need to be cut, severed (i.e., an upper section completely detached from a lower section), or torched to facilitate removal or disposal of a part of the wellbore  20 . For example, the production tubing  16  may be perforated to enable fluid to enter into the production tubing  16 . In other situations, severing the production tubing  16  may facilitate the removal of all the production tubing  16  above the cut. 
     To complete such operations, the downhole tool  14  may hold a non-explosive fuel, such as a thermite fuel  22 , during descent down the wellbore  20 . As shown, an external surface  24  can protect the thermite fuel  22  as the downhole tool  14  descends to a target area  26 . The target area  26  is the location where the downhole tool  14  is meant to perform the operation. The thermite fuel  22  is non-explosive fuel, but once activated, the thermite fuel can burn at a temperature that may exceed 3000 degrees Celsius. The reaction occurs over a long enough period of time that the resultant molten fuel may be directed through a nozzle without causing the external surface  24  to deform due to internal pressure. 
     The thermite fuel includes a combination or a mixture of a metal and an oxidizer. Examples of such metals can include: aluminum, magnesium, chromium, nickel, silver and/or other metals. 
     When the metal is combined or mixed with the oxidizer, a metal oxide is created that can form, or at least partially form, a combustion product(s). Oxidizers that can be used to oxidize the metal can include, for example: cupric oxide, iron oxide, aluminum oxide, ammonium perchlorate, and/or other oxidizers. Applicant incorporates U.S. Pat. No. 8,196,515, having the title of “Non-Explosive Power Source For Actuating A Subsurface Tool” by reference, in its entirety, herein. The ignition point of thermite can vary, depending on the specific composition of the thermite. For example, the metal and the oxidizer may or may not be combined prior to ignition, which can affect the ignition point. As another example and in regard to thermite mixtures, the ignition point of a thermite mixture of aluminum and cupric oxide is approximately 1200 degrees Fahrenheit, while other thermite mixtures or combinations can have an ignition point as low as 900 degrees Fahrenheit. 
     When ignited, the thermite produces a non-explosive, exothermic reaction. The rate of the thermite reaction occurs on the order of milliseconds, while an explosive reaction has a rate occurring on the order of nanoseconds. While explosive reactions can create detrimental explosive shockwaves within a wellbore, use of a thermite-based power charge (non-explosive or deflagration reaction) avoids such shockwaves. 
     The thermite combination can include a polymer, which can be disposed in association with, or as a part of, the thermite combination. The polymer can be of a type that produces a gas responsive to the thermite reaction, which slows the reaction time of the thermite. Usable polymers can include, without limitation, polyethylene, polypropylene, polystyrene, polyester, polyurethane, acetal, nylon, polycarbonate, vinyl, acrylin, acrylonitrile butadiene styrene, polyimide, cylic olefin copolymer, polyphenylene sulfide, polytetrafluroethylene, polyketone, polyetheretherketone, polytherlmide, polyethersulfone, polyamide imide, styrene acrylonitrile, cellulose propionate, diallyl phthalate, melamine formaldehyde, other similar polymers, or combinations thereof. 
       FIG. 2  illustrates a cross-sectional schematic view of the downhole tool  14  of  FIG. 1  firing on the target location  26 . The downhole tool  14  may activate the thermite fuel  22 , which rapidly reacts to produce molten fuel  30  in an internal volume  28  of the downhole tool  14 . As the thermite fuel  22  reacts to form the molten fuel  30 , the molten fuel  30  heats up and expands. As discussed above, the thermite fuel  22  can include polymers or gasifying elements to increase the expansion of the molten fuel  30 . The thermite fuel  22 , in certain embodiments, burns from the center outward, and is naturally heat-insulating. The thermite fuel  22  can thus protect the downhole tool  14  as the thermite fuel  22  burns from the inside toward the outside. To further ensure the external surface  24  does not suffer damage during firing, the downhole tool  14  may include protective elements such as a liner along the internal volume  28 . 
     As the molten fuel  30  continues to expand, the downhole tool  14  projects a molten fuel projection (i.e., spray)  32  at the target area  26 . The molten fuel projection  32  may be shaped by an opening in the downhole tool  14  as described below. A sufficiently focused molten fuel projection  32  may contact the target area  26  with enough force to destroy some or all of the target area  26 . Thus, a hole  34  may be cut or torched through the target area  26  or the production tubing  16 , casing  18 , or further into the formation. Additionally, the hole may include a complete circle of the production tubing  16 , severing the bottom of the production tubing  16  from the top and allowing retrieval of the top production tubing  16 . 
       FIG. 3  illustrates a perspective view of an embodiment of the downhole tool  14  that may be used within the system  10  of  FIGS. 1 and 2 . As illustrated, the downhole tool  14  may include openings  40 . The openings  40  can allow the molten fuel  30  to flow from the internal volume  28  of the downhole tool  14  to the target area  26  where the molten fuel projection  32  can destroy the target  34 . In certain embodiments, the openings  40  are shaped to achieve a specific flow of the molten fuel projection  32 . For example, a round, wide opening  40  would produce a slow molten fuel projection  32  that applies more molten fuel  30  to the inside of the production tubing  16  or the casing  18 . On the other hand, a flat, narrow opening  40  would produce a more focused molten fuel projection  32  that cuts or penetrates through the production tubing  16  or the casing  18 . 
     In certain embodiments, the system  10  may be used to completely sever the production tubing  16 , or other downhole component. In these embodiments, the openings  40  produce molten fuel projection  32  around a significant portion of the circumference of the downhole tool  14 . A significant portion of the circumference means that the molten fuel projection  32  produces a hole  34  in the production tubing  16  such that the target area  26  will be severed substantially completely or completely by pulling on the production tubing  16  from the surface. For such an operation of severing, the downhole tool  14  may include several openings  40  that cover a significant portion of the circumference of the downhole tool  14 . For example, the openings  40  may cover eighty to ninety-nine percent (80%-99%) of the circumference, eighty-five to ninety-five percent (85%-95%) of the circumference, about ninety percent (90%) of the circumference, or some other percentage of the circumference. In the illustrated embodiment, the downhole tool  14  includes four openings  40 . 
     Between the openings  40 , a web protector and/or a pillar  42  can hold the downhole tool  14  together, and can define the shape of the openings  40  by bordering the opening  40  on one side. Additional pillars  42  may border the openings  40  on other sides. As the molten fuel projection  32  projects (i.e., sprays) through the openings  40 , it can weaken the pillars  42  due to heat or contact erosion. For example, heating up pillars  42  made from certain types of steel can make the pillars  42  elastic, and the weight of the downhole tool  14  (i.e., a lower portion  43 ) can stretch the pillars  42 . This can affect the flow of the molten fuel projection  32  by changing the shape of the openings  40 . Additionally, the pillars  42  may, sometimes, be stretched beyond the pillar&#39;s  42  ability to hold the downhole tool  14 , causing the downhole tool  14  to split (i.e., at the openings  40 ). That is, if the pillars  42  are compromised, the lower portion  43  of the downhole tool  14  can break apart from the remainder of the downhole tool  14 . This can cause problems of many types for operation of the system  10 . The lower portion  43  may fall and get stuck within the wellbore  20 , requiring an additional operation for retrieval. Additionally, the breaking of the lower portion  43  may severely hinder the operation of the downhole tool  14  in cutting, destroying, or annihilating the target area  26 . Specifically, if the lower portion  43  splits from the downhole tool  14 , the molten fuel  30  possibly could be poured down the wellbore  20  without contacting, or with minimal contact of, the target area  26 . 
     As mentioned above, the downhole tool  14  may include a liner  44  that protects the inside of the downhole tool  14  from the molten fuel  30 . To ensure that the pillars  42  also remain structurally intact and do not break, the liner  44  may also protect the pillar  42  from the molten fuel  30 , and the liner may have openings that coincide with the openings  40  in the downhole tool  14 . The liner  44  may be constructed from a material that is temperature resistant, and does not react with the thermite fuel  22  or molten fuel  30 . For example, the liner  44  may be constructed from carbon-based materials such as graphite or carbon-fiber. The liner  44  may also include polyetheretherketone (PEEK) a semi-crystalline organic polymer thermoplastic, exhibiting a highly stable chemical structure. The liner  44  may also include other members of the polyaryletherketone (PAEK) polymer group, or other polymers. 
       FIG. 4  illustrates a cross-sectional top view of the embodiment of the downhole tool  14  of  FIG. 3 . The view shows the internal volume  28  and the external surface  24  of the downhole tool  14 , as well as the openings  40  where the molten fuel  30  flows from the internal volume  28  past the external surface  24 . The liner  44 , as illustrated, blocks the molten fuel  30  from impinging on an internal volume face  48  of the downhole tool  14 . The liner  44  also includes liner pillars  46  that block the molten fuel  30  from impinging on the pillars  42 . Without the liner pillars  46 , the molten fuel  30  would be forced against the internal volume face  48  of the pillar  42  during firing. 
     Eventually, the molten fuel  30  and the molten fuel projection  32  flowing past the pillar  42  could erode the internal volume face  48 , and the pillar  42  could fail. The liner pillar  46  can be shaped to direct the molten fuel  30  and the molten fuel projection  32  away from an opening side  50  of the pillar  42 . That is, the liner  44  and the liner pillar  46  may be shaped and/or configured to direct the molten fuel  30  away from all internal sides (i.e., internal volume face  48  and opening side(s)  50 ). For example, the liner pillar  46  may be wider than the pillar  42 , or may have a flare  51 , such that the liner pillar  46  broadens in width further from the internal volume  28 . This broadening can focus the flow of the molten fuel projection  32  away from the opening side  50  of the pillar  42 . 
       FIG. 5  illustrates a cross-sectional top view of an embodiment of a downhole tool  14  that employs web protectors  52  for protection of the pillar(s)  42 . In addition to temperature/heat damage, and erosion just on the internal volume face  48 , the pillars  42  may be eroded from the side due to the molten fuel projection  32 . As the molten fuel projection  32  sprays (i.e., projects) through the openings  40 , the flow may not be laminar. Turbulent eddies of molten fuel projection  32  may curl into the opening sides  50 , causing erosion of the pillars  42 . Therefore, to protect the opening sides  50  and the internal volume face  48  of the pillar(s)  42 , certain embodiments of the downhole tool  14  may employ web protectors  52  to protect the internal volume face  48  and the opening side(s)  50  of the pillar(s)  42 . 
     The web protectors  52  may be constructed of the same material as the liner  44 , or may include different materials. For example, the liner  44  that is lining the internal volume face  48  of the internal volume  28  may include graphite, while the web protector  52  can be made from PEEK material. These types of materials are better suited to resist the heat and erosion of the molten fuel  30  as it passes through the opening  40 . Embodiments tested with web protectors  52  have shown that the pillars  42  suffer much less stretching and weakening, and can therefore be constructed with smaller pillars  42  without breaking. As explained above, having a smaller pillar  42 , and correspondingly larger opening  40  can provide a more thorough cutting of the target area  26 , and thus more efficient and effective use of the downhole tool  14 . 
     The web protector  52  may be customized and manufactured to be installed in specific downhole tools  14 . For example, the web protector  52  may include a body  53  and a contacting side  54  that is shaped to completely contact the pillar  42  on all of the internal sides (e.g., internal volume face  48 , and two opening sides  50 ). The web protectors  52  may be manufactured separately from any liner  44  within the internal volume  28 . The liner  44  may thus be advantageously manufactured as a simple cylinder matching the dimensions of the internal volume  28 . Separate manufacture of the liner  44  and the web protectors  52  may further enable the web protectors  52  to be replaced individually, based on need, and replaced more often or less often than the liner  44 . 
     The web protectors  52  may be held in place around the pillar(s)  42  with a securing connector  56 . The securing connector  56  may include a chemical, magnetic, or mechanical connection that keeps the web protector  52  from moving during descent of the downhole tool  14 , and firing. For example, the connector  56  may include an epoxy that semi-permanently secures the web protector  52  in place. Additionally or alternatively, the connector  56  may include a magnet within the web protector  52  that enables an operator to remove the web protector  52  by hand, without requiring a tool. In certain embodiments, the connector  56  may include a snapping feature that locks or pinches into a corresponding feature on the pillar  42 . Additionally or alternatively, the web protectors  52  may be held in place by inserting the liner  44  after the web protectors  52  have been placed around the pillars  42 . The liner  44  can push the web protectors  52  tightly against the pillars  42  so that the web protectors  52  do not shift or dislodge. 
       FIG. 6  illustrates a perspective view of the embodiment of the downhole tool  14  illustrated in  FIG. 5 . As illustrated, the downhole tool  14  includes the web protectors  52  surrounding the pillar(s)  42 . With the web protectors  52  protecting the pillars  42 , the openings  40  may be narrower or wider without risking damage to the pillars  42 . This enables the molten fuel projection  32  to exit through the opening  40  with more force. A more forceful molten fuel projection  32  penetrates further, which saves time, for example, by using fewer tool runs to complete an operation, and/or using less thermite fuel  22 /molten fuel  30  to complete the required operation. 
       FIGS. 7A and 7B  illustrate a side view of an embodiment of the downhole tool  14  having a web protector  52   a  surrounding pillar connectors  60 . The illustrated embodiment of the downhole tool  14  includes separate pieces for a bottom  62  and a top  64  of the downhole tool  14 . The pillar connectors  60  connect the bottom  62  to the top  64  by threading pillar threads  66  (see  FIG. 7B ) into threaded holes  68 . The threaded holes  68  may be located in the bottom  62  and the top  64 , and may be oppositely threaded such that rotating the pillar connector  60  in a single direction simultaneously screws the pillar threads  66  into the bottom  62  and the top  64 . The pillar connectors  60  may be protected over the entire surface by a cylindrical web protector  52   a  that can be slid around the outside of the pillar connector  60  before it is threaded in place. The web protector  52   a  may further enhance the protection of the pillar connector  60  by being counter sinked within a counter-sink hole  70  in a surface  72  of the opening  40 . Though not illustrated, the top  64  may also include the countersink holes  70  and the threaded holes  68 .  FIG. 8  illustrates a cross-sectional top view of the bottom  62  of the downhole tool  14  shown in  FIGS. 7A and 7B .  FIG. 8  shows the web protector  52   a  surrounding pillar connectors  60  on the surface  72  of the opening  40 . 
     The downhole tool  14  discussed above may be a tool that contains thermite fuel  22 . In other embodiments, the downhole tool  14  may include other non-explosive fuels, such as chemicals that are activated by mixing the chemicals to form a resultant chemical fuel. The resultant chemical fuel may be directed through the nozzle without causing the external surface  24  to deform due to internal pressure. The liner  44  and the web protectors  52  may protect the inside of the downhole tool  14  and the pillars  42  from the chemical fuel in the same manner as discussed above. Some examples of the chemical used to form the resultant chemical fuel include: acids, nitrogen fluoride and mixtures (e.g., nitrogen fluoride and molecular fluoride), nitrogen trifluoride, bromine trifluoride, or solid gases (e.g., nitrogen). 
     While various embodiments usable within the scope of the present disclosure have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention can be practiced other than as specifically described herein.