Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers
  • E21B17/1042—Elastomer protector or centering means
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers

Definitions

• the invention relates to a composite solid centralizer for downhole drilling operations, such as for use in oil or gas wells, which reduces wear and abrasion while the centralizer travels downhole as part of the casing string.
• Oil and gas drilling is a complex process in which a variety of different types of equipment is used.
• a casing typically a cylindrical tube
• This provides structural stability to the well and permits the operator to selectively produce and treat only certain zones.
• a device called a centralizer is positioned around the casing. The purpose of centralizers is at least two-fold.
• the centralizers reduce the torque and drag factors seen by the operator while getting the casing to depth (some are designed to allow the casing string to rotate independently to further reduce friction while running in the hole). Another purpose is to center (or centralize) the casing once it has been run to total depth, so that when the cement is pumped, it can circulate all around the casing string to provide a good cement job. Typically, this means that cement has successfully been placed 360 degrees around the casing without a noticeable“wide” or “narrow” side to the annulus.
• Centralizers are typically formed as hollow-cylindrical tubes, although other types of centralizer geometries are also known.
• cement is pumped around the outer surface of the casing, between the outer surface of the casing and the wall of the well bore, in order to seal the well bore and to structurally support the casing.
• the well can be selectively completed to allow oil to be extracted through the casing in a controlled manner.
• centralizers which are formed of a hollow, cylindrical body having longitudinal blades on an outer surface extending along a length thereof.
• the blades can be solid, or spring-like blades.
• Solid centralizers are typically formed of metal or polymer materials.
• the spring-like blades are typically made of a metal material.
• the invention is directed to a polymer-based solid centralizer with solid polymer blades, where buttons of material specifically designed to reduce wear and abrasion are added to the exterior of the blades to reduce wear and abrasion experienced when running downhole, thereby extending the life of the centralizer and reducing the risk of catastrophic failure of the well.
• One aspect of the invention is a centralizer for use with downhole operations, such as drilling apparatus, which includes a hollow, cylindrical body having an exposed outer surface and formed of a non-metallic material, a plurality of blades formed of non-metallic material, protruding from the outer surface of the hollow cylindrical body, and a plurality of wear buttons positioned on each one of the plurality of blades, each of the wear buttons having a surface designed to reduce friction.
• a centralizer for use in downhole processes which includes a hollow, cylindrical body having an exposed outer surface and formed of a non-metallic composite material, a plurality of non-metallic blades protruding from the outer surface of the cylindrical body and oriented in a parallel or spiral arrangement, and a plurality of substantially cylindrical ceramic wear buttons positioned on each of the plurality of blades, each of the wear buttons having an exposed and smooth curved surface.
• the invention is also directed to a centralizer for use with downhole apparatus, which includes a hollow, cylindrical body having an exposed outer surface and formed of a non-metallic material, a plurality of blades protruding from the outer surface of the hollow cylindrical body, a plurality of wear buttons protruding from each one of the plurality of blades, each of the wear buttons having a surface designed to reduce friction.
• the plurality of blades and plurality of wear buttons are formed of the same non-metallic material.
• the present invention may also provide a non-metallic centralizer for use with a downhole apparatus that comprises a hollow, cylindrical body having an outer surface that has a plurality of blades protruding outwardly from the outer surface, and the plurality of blades are formed of a first non-metallic material.
• a plurality of wear buttons are associated with one or more of the plurality of blades.
• Each of the plurality of wear buttons is formed of a second non-metallic material that has a static coefficient of friction to steel that is equal to or greater than a static coefficient of friction to steel of the first non-metallic material.
• the wear buttons are configured to reduce abrasive forces exerted upon the centralizer when run into the downhole apparatus.
• the static coefficient of friction to steel of the first non- metallic material is about 0.17 and the static coefficient of friction to steel of the second non- metallic material is about 0.3; the static coefficient of friction to steel of the blade’s non- metallic material is less than 0.8 and the static coefficient of friction to steel of the wear buttons’ non-metallic material is greater than the static coefficient of friction to steel of the blade’s non- metallic material and less than 0.8; the first non-metallic material is a polymer or composite polymer; the second non-metallic material is a polymer or composite polymer; and/or the second non-metallic material is polytetrafluoroethylene, polyetheretherketone, dicyclopentadiene polymer, ceramic, carbide, zirconia, or combinations thereof.
• each of the plurality of wear buttons has an exposed wear face that is smooth and rounded; each of the plurality of blades includes a bevel at each end thereof and at least one of the plurality wear buttons is disposed in the bevel in each end; each of the plurality of blades includes at least four of the wear buttons, each of the wear buttons is spaced equally apart along a length of each of the plurality of blades.; and/or the plurality of wear buttons are disposed in the one or more of the plurality of blades such that the plurality of wear buttons do not extend beyond a maximum outer diameter of the centralizer defined by the plurality of blades.
• the present invention may yet further provide a non-metallic centralizer for use with a downhole apparatus, that comprises a hollow, cylindrical body that has an outer surface and first and second opposite open ends and a plurality of blades protruding outwardly from the outer surface where each of the plurality of blades extends from near or at the first open end to near or at the second open end of the hollow cylindrical body.
• the plurality of blades defining a maximum outer diameter of the centralizer and are formed of a non-metallic material.
• a plurality of wear buttons are disposed in one or more of the plurality of blades such that the plurality of wear buttons do not extend beyond a maximum outer diameter of the centralizer defined by the plurality of blades.
• Each of the plurality of wear buttons being formed of a non-metallic material and are configured to reduce abrasive forces exerted upon the centralizer when run into the downhole apparatus.
• the plurality of wear buttons are positioned below or at an outermost surface of the one or more of the plurality of blades; the one or more of the plurality of blades include recesses in the outer most surface, each recess receives one of the plurality of wear buttons; each of the plurality of wear buttons has a smooth wear face that is exposed at the outermost surface of the one or more of the plurality of blades; each of the smooth wear faces is rounded; each of the plurality of blades has a length between first and second blade ends corresponding to the first and second opposite open ends, respectively, of the cylindrical body, at least one of the plurality of wear buttons is located at each of the first and second blade ends; one or more of the plurality of wear buttons are located between the first and second ends; each of the first and second blade ends includes a bevel and the at least one of the plurality of wear buttons is positioned in the bevel of the first and second blade ends; the non-metallic material of the plurality of wear buttons has a static coefficient of
• FIG. 1 is a perspective view of a centralizer in accordance with an embodiment of the invention.
• FIG. 2 is side plan view of a blade of the centralizer illustrated in FIG. 1 ;
• FIG. 3 is a perspective view of a centralizer in accordance with an embodiment of the invention.
• FIG. 4 is a perspective view of a centralizer in accordance with an embodiment of the invention.
• FIG. 5 is a partial cross-sectional view of a centralizer in accordance with another embodiment of the invention.
• FIG. 6 is an end plan view of the centralizer illustrated in FIG. 5;
• FIG. 7 is a partial perspective view of the centralizer illustrated in FIG. 5.
• the solid centralizer of the invention may be used in downhole applications, such as in oil and gas wells, to help to center the casing in the wellbore.
• cement is poured around the outer surface of the casing, between the outer surface of the casing and the wall of the well bore, in order to seal the well bore and to structurally support the casing. If the casing is not centered in the well bore, the annular cement layer will not form a strong bond in the area where the casing makes contact with the wall of the well bore, thus reducing the mechanical integrity of the well.
• the invention provides a non-metallic solid centralizer that is easy to handle in the field and that reduces wear down caused by the abrasive effect of the run-in-hole and pumping processes.
• the centralizers disclosed herein are preferably formed of a non-metallic material, so as to decrease their weight and make them easier to handle when in use.
• the centralizers of the invention may be formed of, for example, polymers, including plastics, resins, phenolic-based compounds, and nylon-based compounds, composites, such as filament wound composites formed of carbon fiber or fiberglass materials, and injection grade materials. This list is not exhaustive, and any non-metallic material that provides the structural integrity similar to those described may be used to form the centralizers of the invention.
• a centralizer 100 is generally formed of a hollow, cylindrical body 102 (the“body 102”) having an outer surface 104.
• the centralizer 100 includes a plurality of protruding blades 106 extending along a length of the outer surface 104 of the body 102.
• each of the blades 106 extends along the entire length of the outer surface 104 of the body from one end to the other end, i.e. the blades are straight along the longitudinal body 102 of the centralizer 100.
• the blades 106 are oriented such that they are parallel to one another and parallel to an axis A upon which the length of the body 102 extends.
• the blades 106 may be formed integrally with the body 102, or the blades 106 may be coupled to the body 102 using any attachment mechanisms known in the art.
• each of the blades 106 may have a generally rectangular shape, with beveled edges 112 at either end.
• the blades 106 may not have the beveled edges 112 and may have a purely rectangular shape.
• the blades 106 may be ovular, such that the blade 106 has a slight curvature from one end to the other end.
• the centralizer 100 further includes a plurality of wear buttons 108 that are positioned on each of the blades.
• each of the blades 106 has at least two (2) wear buttons 108, but preferably at least three (3) wear buttons 108, and more preferably at least four (4) wear buttons 108 (as illustrated in FIG. 1). It should be noted, however, that the number of wear buttons 108 on each blade 106, and in total, may vary depending on the size of the centralizer 100 and the particular application.
• the wear buttons 108 are preferably positioned such that there is one at either end of the blade 106, such that they are located at the interface of the maximum outer diameter of the blade 106 and the entry angle of the centralizer, otherwise known as the beveled edge 112.
• the wear buttons 108 are preferably spaced equally apart from one another along each of the blades 106 so as to evenly distribute the load upon any given blade 106.
• each wear button 108 may take a variety of shapes and sizes, as long as their exposed surface 110 (see FIG. 2) has a smooth interface so as not to induce“grabbing” or “biting” into the casing material or formation as the centralizer 100 is run into the hole, which would increase the abrasive forces imposed on the centralizer 100.
• each wear button 108 is generally formed of a substantially cylindrical shape having an exposed surface 100 that takes the shape of a curved face aligned with axis A of the length of the body 102 (see FIG. 1).
• the wear buttons 108 may have a substantially spherical or ovular shape, or any other geometry that is smooth on the exposed surface 110.
• the wear butons 108 are preferably formed of a hard, resilient material that is different than the non-metallic material used to form the rest of the centralizer 100.
• the material used to form the wear butons 108 may include, but is not limited to, ceramic, polyetheretherketone (PEEK), carbides, zirconia, or combinations thereof.
• PEEK polyetheretherketone
• These non-metallic materials will generally have a coefficient of friction to steel that is less than 0.8 (value for steel on steel), preferably with coefficients of friction to steel less than 0.35 (bronze on steel), more preferably with coefficients of friction to steel that are largely similar to 0.05 (PTFE on steel).
• each of the wear buttons 108 is formed of the same material, such as one of those set forth above.
• the wear butons 108 may be formed of a mixture of materials, such as one or more of those set forth above.
• each buton 108 may be made of one of the materials listed above, but the blades 106 may have butons 108 of different materials installed, such as if certain parts of the blades 106 are expected to receive the most wear, potentially higher quality, more expensive material can be used for butons in that area, where less efficient but less expensive material may be used for the remaining butons 108.
• the wear butons 108 are coupled to each of the blades 106 using either chemical or mechanical atachment methods.
• the butons 108 are molded into and made integral with the blades 106. It should be noted that while the preferred embodiments discuss butons 108, the invention could use strips of wear resistant material or other types of configurations of the non-wear material where the material is designed to be in contact with the casing or formation while running in the hole without catching or grabbing so as to redistribute the observed frictional force across the entire strip and not isolate it to a singular buton.
• a centralizer 300 has generally the same shape as centralizer 100, but the blades 306 are oriented in a spiral patern along the length of the body 102.
• the centralizer 300 of FIG. 3 also preferably includes wear butons 108 similar to those illustrated in FIGS. 1 and 2, with similar shape, size and location, or any other geometry contemplated herein.
• the non-wear material could be applied in strips or other configurations to reduce wear and abrasion going in the hole.
• centralizer 400 has generally the same shape as centralizer 100, but the blades 406 are formed of the same material as the wear buttons 108, including those example materials set forth herein.
• each singular pad has the properties of the wear buttons 108, but encompasses the whole blade 406.
• the blades 406 may be formed integrally with the wear buttons 108, or the wear buttons 108 may be attached using the mechanisms set forth herein to each of the blades 406.
• FIGS. 5-7 illustrate a non-metallic centralizer 500 according to a further exemplary embodiment of the present invention that comprises a hollow, generally cylindrical body 502 that has an outer surface 504, a plurality of protruding blades 506 protruding outwardly from outer surface 504, and a plurality of wear buttons 508 associated with the blades 506 configured to reduce abrasive forces exerted upon the centralizer 500 when it is run into the downhole apparatus, similar to centralizer 100 according to the first embodiment.
• the body 502 has a length with opposite first and second opposite open ends 510 and 512.
• Each of the blades 506 may extend the length of the body 502 such that each blade 506 extends from near or at the first open end 510 to near or at the second open end 512, as seen in FIG. 7.
• the blades 506 may extend along a length of the body’s outer surface 504 in a straight or spiral pattern orientation, similar to the above embodiments.
• the blades 506 may be formed integrally with the body 502 or the blades 506 may be coupled to the body 502 using any attachment mechanisms known in the art.
• Each of the blades 506 may have a generally rectangular shape, with opposite ends 514 and 516 that generally correspond to the body’s open ends 510 and 512, respectively.
• Each blade end 514 and 516 may have a bevel or beveled edge 518. In an alternative embodiment, each blade end 514 and 516 may be curved instead of beveled.
• the wear buttons 508 are disposed in at least one and preferably all of the blades 506 such that the wear buttons 508 are flush with or just under the outermost surface 520 of each blade 506, as seen in FIG. 5, with each wear button 508 having a wear face 530 that is exposed near or at outermost surface 520. That is, the wear buttons 508 preferably do not extend beyond the outermost surface 520 of the respective blade 506.
• Each of the blades 506 may have a plurality of the wear buttons 508 disposed therein with at least one wear button 508 positioned in the bevel 518 at each of the blade ends 514 and 516.
• the wear buttons 508 are preferably positioned at either end 514 and 516 of the blade 506, such that they are located at the interface of the maximum outer diameter D and entry angle (into the downhole) of the centralizer 500. Like in the above embodiments, the wear buttons 508 may be spaced equally apart from one another along each of the blades 506 so as to evenly distribute the load upon any given blade 506.
• the blades 506 are formed of a first non-metallic material and the wear buttons 508 are formed of a second non-metallic material where the second non- metallic material has a static coefficient of friction to steel that is equal to or greater than the static coefficient of friction to steel of the first non-metallic material.
• the static coefficient of friction of a material to steel is the friction force between an object made of that material and an object made of steel, respectively, when neither object is moving.
• the wear buttons 508 may be formed of any non-metallic material as long as the non-metallic material of the wear buttons 508 has a static coefficient of friction to steel that is equal to or greater than the static coefficient of friction to steel of the non-metallic material of the blades 506. This ensures that the wear buttons 508 will still provide wear protection to the centralizer 500 even if or when the blades 506 wear down.
• the static coefficient of friction to steel of the blades’ non- metallic material is about 0.17 and the static coefficient of friction to steel of the wear button’s non-metallic material is about 0.3.
• the static coefficient of friction to steel of the blade’s non-metallic material is less than 0.8 and the static coefficient of friction to steel of the wear buttons’ non-metallic material is greater than the static coefficient of friction to steel of the blade’s non-metallic material and also less than 0.8.
• Table 1 lists exemplary non-metallic materials for either the blades 506 or the wear buttons 508. These non- metallic materials will generally have a coefficient of friction to steel that is less than 0.8 where a value of 0 means there is no friction at all between the objects.
• each wear button 508 has a generally spherical shape with an exposed wear face 530 that takes the shape of a curved or rounded face generally aligned with the length of the body 502.
• the blades 506 extending outwardly from the body’s outer surface 504 and their outermost surfaces 520 define the maximum outer diameter D of the centralizer 500, as seen in FIG. 6.
• the wear buttons 508 are disposed in each blade 506 such that they do not extend beyond the maximum outer diameter D of the centralizer 500. As such, the exposed wear faces 530 of the wear buttons 508 may be at or just underneath the outermost surface 520 of the blades 506.
• each blade 506 includes one or more recesses 532 that are each positioned and sized to receive a corresponding wear buttons 508.
• the wear buttons 508 may be chemically fastened, e.g. glued or adhered in place in the recesses 532, or mechanically fastened, i.e. molded in the recesses 532.
• the wear buttons 508 can be embedded in the blades 506, such as by insert molding them into the blades 506.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
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• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)

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Citations (2)

• 2020
  • 2020-05-13 WO PCT/US2020/032699 patent/WO2020256859A1/en active Application Filing
  • 2020-05-13 NO NO20210109A patent/NO20210109A1/en unknown
  • 2020-05-13 BR BR112021001897A patent/BR112021001897A2/pt unknown
• 2021
  • 2021-02-01 SA SA521421164A patent/SA521421164B1/ar unknown

Patent Citations (2)

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