Patent Application
20080029305
This invention pertains of borided parts for wear surfaces in equipment for use in earth boring, well completion and fluid extraction.
Oil exploration is a specialized process that combines elegant scientific models and brute force prospecting. Seismic prospecting techniques employ sound waves to find probable oil reserves thousands of feet below the Earth's surface, and sophisticated modeling techniques are used to characterize the geology of those locations. Once a likely site is identified, a hole is drilled into the ground until oil or gas is found or the driller decides to abandon the site for a likelier prospect. At some sites, the hole is drilled using a top head drive attached to a length of hollow pipe. As the hole becomes deeper, extra sections are added to the pipe. In addition, a continuous stream of drilling “mud,” an aqueous slurry containing clay and other chemicals, is pumped through the drill pipe and through holes in the drill bit to cool the bit. The mud also coats the side of the hole to prevent collapse and carries crushed rock to the surface. The mud is pumped into the hole by a mud, or slush, pump.
The drill bit has to cut through rock and gradually wears. In addition, the mud and the cuttings traveling to the surface wear not only the drill bit but components of the mud pump. Drilling (and mud pumping) is conducted 24 hours a day, but if any of the parts wear out, the entire operation may need to be halted while the part is repaired. The components of the mud pump, located at the surface, are easily accessible. On the other hand, the entire length of thousands of feet of hollow pipe have to be removed section by section to replace the drill bit. As a result, it is desirable to increase the useable lifetime of all the wearing parts used in oil drilling.
As used herein, the terms “boriding” and “boronizing” are used interchangeably and indicate the development of a boron-containing layer on a metal substrate, such that boron diffuses into the metal and reacts with a component of the metal or a component of the metal diffuses to the boron-containing layer and reacts with the boron, or both.
As used herein, the term “fluid extraction” refers to the removal of oil, natural gas, water, and/or other fluids from underground.
As used herein, the term “metallic” refers to a material that includes at least 50% metal elements (e.g., Fe, Ti, Zn, etc.) in a metallic, intermetallic, or alloy phase. In some embodiment, the material may include at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% metal elements in a metallic, intermetallic, or alloy phase.
As used herein, the terms “mud pump” and “slush pump” are used interchangeably.
The invention is described with reference to the several figures of the drawing, in which,
In one embodiment, at least a first portion of a surface of a component for use in combination with a second component during earth-boring, well completion (e.g., fracturing and cementing the well after drilling), or fluid extraction comprises a metallic material and is borided. In certain embodiments, the borided portion does not wear against a metallic surface of the second component during use. In some embodiments, the component is not a tricone bit. The component may be fabricated from a ferrous or non-ferrous metal or metal alloy. In some embodiments, the metal or metal alloy may be steel, titanium, or a titanium or chromium alloy. In certain embodiments, the first portion is substantially metallic, or may be at least 80% metallic, at least 85% metallic, at least 90% metallic, or at least 95% metallic.
Various equipment for use in earth-boring, well completion, and fluid extraction can benefit from the teachings of the invention. During exploration and drilling for fluids such as oil, natural gas, and water, drilling hardware is subjected to abrasive, erosive, and corrosive conditions. These wear modes reduce the useful life of hardware components and increase drill rig operating costs. The teeth of drill bits used in oil and gas exploration and drilling are often made from cemented tungsten carbide, due to its resistance to abrasion and erosion. However, due to the difficult nature of working with tungsten carbide, fabrication of the teeth for drill bits is complex, labor intensive, and costly. Steel teeth, which are easier and less costly to fabricate, are sometimes used, however they may not be sufficiently wear-resistant for some applications. The surface of the drill bit, the roller cones to which the teeth are secured, and the nozzle from which drilling mud is directed into the drill hole are often fabricated from steel as well. Boriding can increase the wear resistance of all of these components, allowing them to be fabricated from steel or other metals instead of tungsten carbide or other cermets or metal-matrix composites. Wear also is a problem for many other components used in oil and gas drilling, such as, for example, radial and thrust bearings, mechanical couplings, wear pads, flow diverters and restrictors, mud pump liners, and impellers.
Additional parts that may benefit from boriding include various fishing tools, apparatus to recover parts from within a bore. Because these components tap a thread in the component to secure themselves to the component, they often can only be used once for a particular size component, after which the tap/thread is too worn to recover a second component of the same size. These tools are often tapered and thus can be used to recover a component having a larger diameter even after the smaller diameter regions become worn. However, boriding can harden the surface sufficiently that the fishing tool can be used two or more times to recover parts from a bore. Exemplary fishing tools include but are not limited to spears, taper taps, and overshots.
Many other components of exploration and drilling equipment are subject to wear by corrosion, abrasion, or erosion, including, for example, radial and thrust bearings, mechanical couplings, wear pads, flow diverters and restrictors, mud and cement pump liners and impellers, drill pipes, valves, directional drilling assemblies, hanger assemblies, fishing tools (e.g., spears, taper taps, and overshots), percussion assemblies, nozzles, and core lifters. Many different coating methods have been tried for improving the abrasion and corrosion resistance of these components. These include thermal spraying and application carbide composite coatings, as well as nickel and chrome plating. While these coatings can improve the life of the part, further improvements can provide dramatic decreases in downtime and replacement costs.
During earth-boring, mud pumps are used to circulate pumping mud in the drill hole as the mud carries cuttings to the surface. The extent and mode of wear to the pump components is determined by the abrasiveness, particle concentration, particle size, velocity, pH, and other characteristics of the particles and the fluid as well as the operating conditions of the pump such as flow rate, pressure, etc. Depending on the site, pumps may need to run continuously for weeks or months at a time. Wear results in part from the flow of particles within the mud abrading the surfaces of the pump's components. As the surfaces of these components wear away even a small amount, the ability of a pump to maintain pressure and convey the pumping mud becomes greatly diminished. When pump components wear beyond a certain limit and begin to perform below acceptable process limits, the pumps and/or process lines must be shut down and the components or entire pumps must be replaced.
In an exemplary embodiment, at least some of the metal bearing surfaces of a mud, or slush, pump are borided.
It is contemplated that other components employed in earth-boring, well completion, and fluid extraction may also benefit from boriding. For example, DTH (down the hole) hammer bits wear against rock as they drill the well, while the internal components of the hammers wear against each other. While these hammer bits often have carbide inserts, it is contemplated that the lifetime of the metallic portions of the hammer bit may also be extended by boriding. Fracturing tubes may be abraded and/or corroded by the fracturing fluid. Valve seats and valve bodies abrade against the pumping mud but also against each other. Drill pipes are initially abraded by the pumping mud, foam (air drilling), brine, and the rock it carries out of the well and later by fluids being extracted by the well and any particulate matter they carry. Drill pipes may also be corroded by fluids such as water that are pumped into the well. Abrasion of core lifters can reduce the length of cores that can be cut and brought to the surface and, in extreme cases, can jeopardize the cohesion of the core sample, making recovery difficult. Directional drilling assemblies may experience uneven wear as a result of the deviation of the drilling direction from the vertical. Plungers for cement pumps abrade against the rocks in the cement and are also chemically eroded by the elevated pH of lime-based materials. Flow diverters and flow restrictors may wear not only from particulates in the extracted fluid but also from the fluid itself. It is contemplated that boriding of radial and thrust bearings may not only reduce wear but may also reduce fatigue by reducing friction during use. Additional parts that may benefit from boriding include but are not limited to mechanical couplings, wear pads, impellers, hanger assemblies, percussion assemblies, nozzles, rollers, cams, and shafts.
As discussed above, the lifetime of drilling and pump parts that are constantly abraded by rock from a well is determined in part by the tribological properties of the components. The use of diffusion-based treatments such as nitriding, carburization, and boriding to increase surface hardness and resistance to wear is well known. Boriding can produce a harder surface than nitriding or carburization and is suitable for some steel alloys for which nitriding or carburization are less optimal. Boriding also improves the corrosion resistance and reduces the coefficient of friction more than carburization, increasing the lifetime of parts. Even a 10% improvement in part life can create immense savings over the course of drilling and completing a single well. Other techniques for increasing surface hardness include the simple deposition of a boron-containing layer at the surface of a material. For example, electrochemistry may be employed to form a layer of iron boride at the surface of a component. Alternatively, superabrasive composites including materials such as diamond or cubic boron nitride may be electroplated onto metallic components, or metal/metal boride mixtures may be thermally sprayed onto components. However, layers formed by these methods may not be chemically or mechanically integrated with the bulk material. Boriding provides greater integration of the boron-containing layer with the substrate. This integration increases the strength of the interface between the boride-containing layer and the substrate, further reducing galling, tearing, seizing, and other forms of wear in which a material flakes from the surface.
A variety of boriding techniques may be used to improve the tribology of wearing parts for use in earth-boring, well completion, and fluid extraction. In some embodiments, boriding includes two processes: the generation of a thin boride layer at the surface of the material and the growth of that layer by diffusion into the bulk material. In some cases, the depth of the boron-containing diffusion zone may be over seven times thicker than the surface boride layer (ASM Handbook, Volume 4, ASM International, Materials Park, Ohio, 1994). The diffusion layer increases the resistance of the layer to delamination and also helps reduce cracking resulting from differential rates of thermal expansion during processing. In addition, diffusion of the boron into the bulk material may improve the fatigue performance of the component.
An exemplary boriding method is pack boriding. A boron-containing powder is packed around a workpiece in a refractory container and heated. Alternatively, a paste may be applied to the workpiece and heated, or a fluidized bed may be employed. In another embodiment, boriding may be performed with a gas or plasma, allowing the boriding to be performed without annealing the core of the work piece, which can lead to grain coarsening and softening of the base material. Plasma boriding also allows quicker diffusion of reactive elements and higher velocity impact of reactive boron species against the surface of the workpiece. In some embodiments, it may be desirable to have a hardened surface around a more malleable core. The surface heating imposed during plasma boriding allows the difference in mechanical properties between the various regions of the part to be maintained. Exemplary boriding methods are disclosed in U.S. Pat. Nos. 3,926,327, 4,610,437, 4,637,837, and 6,783,794. In another embodiment, a potassium haloborate may be decomposed to the potassium halide salt and the boron trihalide, which is then fed into an inert gas stream for plasma boriding. In one embodiment, the potassium haloborate is potassium fluoroborate. It is contemplated that this technique facilitates boriding of larger parts more cheaply and safely than plasma boriding techniques employing organoborates or boron halides.
It is contemplated that use of boriding to surface harden components allows them to be made from materials that are not traditionally employed in earth-boring. For example, pump liners are often fabricated from chromium-containing steels. However, the use of a borided surface may enable these components to be fabricated from chromium alloys, titanium, and titanium alloys, for example, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-10V-2Fe-3Al, Ti-0.3Mo-0.8Ni, Ti-0.2Pd, etc. TiB2 has a hardness of 3300 vickers, which can greatly improve the lifetime of components fabricated from borided titanium-containing metals.
In another embodiment, a system for preparing a well for fluid extraction includes a first component having a surface, at least a first portion of which comprises a metallic material that is borided. In certain embodiments, the system further includes a second component having a metallic portion, and the first portion does not wear against the metallic portion during use. In certain embodiments, the component is not a tricone bit. In certain embodiments, the system includes a drill, a mud pump, a cement pump, and/or a fracturing tube. The system may also include segments of a well liner.
In a further embodiment, a method of preparing a component for wearing against a material transported during earth-boring, well completion, or fluid extraction, the component having a surface, at least a portion of which comprises a metallic material, includes boriding at least the first portion. In certain embodiments, the component is not a tricone bit.
In a further embodiment, at least a first portion of an interior surface of a pump liner for use in earth-boring, well completion, or fluid extraction is borided. In another embodiment, a first portion of a surface of a component for use in earth-boring, well completion, or fluid extraction includes a substantially metallic material that is borided. According to another embodiment of the invention, the component is a valve seat, valve body, mud pump liner, piston hub, sucker rod, piston rod, fishing tool, or plunger.
A valve seat and valve body were borided by pack boriding. One sample was borided for 8 hours at 1700° F.; the second was treated for 24 hours at 1500° F. Micrographs of the boride layer, showing the sawtooth pattern frequently observed in borided steels, are shown in
Four borided valve bodies and valve seats, with urethane insert, as well as four non-borided valve bodies and valve seats (control), with urethane inserts, were installed on a Continental Emsco DB 550 Duplex mud pump. The pump was run under normal operating conditions for four months, at which point the non-borided parts had to be replaced. The borided parts continued to work effectively.
Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.
This application claims priority to U.S. Provisional patent application Ser. No. 60/745,228, filed Apr. 20, 2006, the entirety of which is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60745228 | Apr 2006 | US |
