Patent Publication Number: US-2015060042-A1

Title: Electrical submersible pump and pump system including additively manufactured structures and method of manufacture

Description:
BACKGROUND 
     The present disclosure relates to electric submersible pumps. More particularly, the present disclosure relates to electric submersible pumps configured to provide improved contaminant tolerance and resulting increase in life span of the pump and pump components. 
     Electric submersible pump systems are used in a wide variety of environments, including wellbore applications for pumping production fluids, such as water or petroleum. Electric submersible pump systems typically include, among other components, a submersible pump that provides for the pumping of high volumes of fluid, such as for use in oil wells which produce large quantities of water, or high volume water wells and a submersible motor for operating the electric submersible pump. 
     A typical electric submersible pump utilizes numerous stages of diffusers and impellers, referred to as pump stages, for pumping fluid to the surface from the well. During operation, the impellers are configured to rotate within the diffusers. It is known in the art to make impellers and diffusers from a cast alloy by machining operations, such as milling, turning, etc. 
     During operation of these types of submersible pumps, tolerance to contaminants in the pumped fluid, and in particular sand, is of great concern. More particularly, tolerance to contaminants in the pumped fluid is a critical functionality that can enhance the lifespan of the electric submersible pumps. If a fluid being pumped contains a significant amount of contaminants, and more particularly entrained abrasive contaminants, such as sand, the abrasive particles will abrade and/or erode the components, and in particular the pump impellers and diffusers, and thereby shortening the life of the pump. To minimize the detrimental effects of these contaminants, recent developments have provided submersible pumps that include features to reduce material loss due to contaminants. One of these features includes utilizing coatings on the component substrate, such as the cast alloy, thus providing for a harder surface area that is less susceptible to damage by the impact of these contaminants. In addition, the inclusion of other wear resistant pump components, comprised of harder material than the impeller and diffuser, may be utilized such as bearings formed of hardened material. However, inclusion of these coating and or wear resistant components is considerably more expensive than conventional pump stage components. 
     In the field of oil and gas, it is typical to remove a pump from a well for servicing periodically. If contaminants have abraded the pump components severely, the pump may potentially have to be removed earlier than the usual life. The cost for removing an electric submersible pump, including lost production time, can be quite expensive, particularly with regard to wells not easily accessible, such as offshore drilling wells. 
     Accordingly, it is desired to provide for an electric submersible pump, including conventional pump stage components having improved tolerance to contaminants, such as sand, thus providing for an increase in the lifespan of the pump. Further, there is a need for an electric submersible pump that allows continuous operation of the electric submersible pump system for an extended period of time. 
     BRIEF DESCRIPTION 
     These and other shortcomings of the prior art are addressed by the present disclosure, which provides an electric submersible pump, an electrical submersible pump system and a method of manufacturing an electric submersible pump. 
     One aspect of the present disclosure resides in an electric submersible pump. The electric submersible pump comprising: a housing; at least one impeller disposed in the housing; and at least one diffuser disposed in the housing and configured in cooperative engagement with the at least one impeller. At least one of the at least one impeller and the at least one diffuser is configured as a monolithic additively manufactured structure comprised of a metal matrix composite. 
     Another aspect of the present disclosure resides in an electrical submersible pump system. The electrical submersible pump system comprising: an electric submersible pump; and an electric motor configured to operate the electric submersible pump. The electric submersible pump comprises: a housing; at least one impeller; and at least one diffuser. The at least one impeller and the at least one diffuser are disposed within the housing and configured in cooperative engagement. The housing, the at least one impeller, and the at least one diffuser define an internal volume within the housing, said internal volume configured to receive a fluid. At least one of the at least one impeller and the at least one diffuser is configured as a monolithic additively manufactured structure comprised of a metal matrix composite. 
     Yet another aspect of the disclosure resides a method of manufacturing an electric submersible pump. The method comprising: (a) forming at least one impeller disposed in a housing; and (b) forming at least one diffuser disposed in the housing and configured in cooperative engagement with the at least one impeller. At least one of the at least one impeller and the at least one diffuser is configured as a monolithic structure comprised of a metal matrix composite. At least one of steps (a) through (b) is carried out by direct metal laser sintering. 
     Various refinements of the features noted above exist in relation to the various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the present disclosure without limitation to the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a side view of an electric submersible pump disposed within a wellbore in accordance with one or more embodiments shown or described herein; 
         FIG. 2  is a schematic sectional view of a portion of an electric submersible pump assembly in accordance with one or more embodiments shown or described herein; 
         FIG. 3  is a schematic sectional view of a portion of the electric submersible pump assembly of  FIG. 2  in accordance with one or more embodiments shown or described herein; 
         FIG. 4  is an isometric view of an electric submersible pump diffuser in accordance with one or more embodiments shown or described herein; 
         FIG. 5  is an isometric view of an electric submersible pump impeller in accordance with one or more embodiments shown or described herein; 
         FIG. 6  is an enlarged view of a portion of a metal matrix composite material of an electric submersible pump component in accordance with one or more embodiments shown or described herein; and 
         FIG. 7  is a flowchart depicting an embodiment of an additive manufacturing method for producing the effusion plate in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure will be described for the purposes of illustration only in connection with certain embodiments; however, it is to be understood that other objects and advantages of the present disclosure will be made apparent by the following description of the drawings according to the disclosure. While preferred embodiments are disclosed, they are not intended to be limiting. Rather, the general principles set forth herein are considered to be merely illustrative of the scope of the present disclosure and it is to be further understood that numerous changes may be made without straying from the scope of the present disclosure. 
     As described in detail below, embodiments of the present disclosure provide a system and method for monolithic design and manufacture of an electric submersible pump. The present disclosure further provides embodiments of a system and method for monolithic design and manufacture of an electric submersible pump manufactured via additive manufacturing techniques. Using such techniques, the monolithic design so produced may provide improved tolerance to contaminants. 
     The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another and intended for the purpose of orienting the reader as to specific components parts. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. The modifier “about” used in connection with a quantity is inclusive of the stated value, and has the meaning dictated by context, (e.g., includes the degree of error associated with measurement of the particular quantity). Accordingly, a value modified by a term or terms, such as “about”, is not limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. 
     In the following specification and the claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. As used herein, the term “or” is not meant to be exclusive and refers to at least one of the referenced components being present and includes instances in which a combination of the referenced components may be present, unless the context clearly dictates otherwise. In addition, in this specification, the suffix “(s)” is usually intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., “the impeller” may include one or more impellers, unless otherwise specified). Reference throughout the specification to “one embodiment,” “another embodiment,” “an embodiment,” and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. Similarly, reference to “a particular configuration” means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the configuration is included in at least one configuration described herein, and may or may not be present in other configurations. In addition, it is to be understood that the described inventive features may be combined in any suitable manner in the various embodiments and configurations. 
     As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances, an event or capacity can be expected, while in other circumstances the event or capacity cannot occur—this distinction is captured by the terms “may” and “may be”. 
     Referring to  FIG. 1 , an exemplary electric submersible pump (ESP) system  10  including portions manufactured via additive manufacturing techniques is illustrated wherein the ESP system is disposed within a wellbore  12 . In one embodiment, the wellbore  12  is formed in a geological formation  14 , for example, an oilfield. The wellbore  12  is further lined by a casing  16 , as indicated in  FIG. 1 . In some embodiments, the casing  16  may be further perforated to allow a fluid to be pumped (referred to herein as “production fluid”) to flow into the casing  16  from the geological formation  14  and pumped to the surface of the wellbore  12 . 
     As illustrated in  FIG. 1 , the ESP system  10  includes an electric submersible pump  20 , an electric motor  22  configured to operate the electric submersible pump  20 , and an electric cable  24  configured to power the electric motor  22 . As noted earlier, the ESP system  10  according to some embodiments of the invention is disposed within a wellbore  12  for continuous operation over an extended period of time. Accordingly, in such embodiments, the ESP system  10  and the components of the ESP system  10  may be subjected to extreme conditions such as high temperatures, high pressures, and exposure to contaminants, such as sand. As further illustrated in  FIG. 2 , in an embodiment, the ESP system  10  further includes a gas separator  26  and a seal  28 . In some embodiments, the ESP system  10  may further include additional components such as bellows or springs (not shown). 
     In an embodiment, the present invention provides an electric submersible pump manufactured via additive manufacturing techniques that is capable of withstanding high temperatures, high pressures, and exposure to contaminants. With reference to  FIGS. 2-4 , the electric submersible pump  20  according to an embodiment is a multi-stage unit with the number of stages being determined by the operating requirements. Each stage consists of a driven impeller and a diffuser manufactured via additive manufacturing techniques (described presently) which directs flow to the next stage of the pump. In an embodiment, the electrical submersible pump  20  is configured as a centrifugal pump comprising one or more pump stages  30 . In the embodiment illustrated in  FIG. 3 , the electric submersible pump  20  is comprised of a plurality of pump stages  30 . Each pump stage  30  is comprised of at least one impeller  34  and at least one diffuser  36 , (as best illustrated in  FIGS. 3 and 4 ) stacked on a common shaft  38  extending at least the length of the pump  20  and cooperatively engaged one with the other. The one or more pump stages  30 , and more particularly the at least one impeller  34  and at least one diffuser  36  are disposed within a housing  40 . The shaft  38  extends concentrically through the housing  40  and is rotated by the electric motor  22 , thus driving the pump  20 . In an embodiment, the electric submersible pump  20  may include one or more rotating impellers  34  and one or more stationary diffusers  36  that can be assembled in either floater or compression configurations to meet performance requirements. 
     In a particular configuration, each of the at least one impellers  34  is configured to rotate within a diffuser  36  during operation of the pump  20 . The diffuser  36  is stationarily mounted within the housing  40 . It has been found that the number of impellers  34  needed to produce a given flow rate at a given pressure is inversely proportional to impeller speed. More particularly, if the impeller speed is increased by a factor of 3, the number of impellers  34  can be reduced by the same ratio and produce the desired flow rate and pressure. In an embodiment, the at least one impeller  34  and the at least one diffuser  36  define an internal volume  42  within the housing  40 , said internal volume  42  configured to receive a fluid  44  as indicated in  FIG. 3 . 
     In an embodiment, the internal volume  42  is configured such that there is fluid communication between the at least one impeller  34 , the at least one diffuser  36  and the fluid  44  that the internal volume  42  may contain. The term “fluid communication”, as used herein, means that the fluid  44  passing through the electric submersible pump  20 , is in contact with the internal volume  42  of the electric submersible pump  20 , and more particularly is in contact with the at least one impeller  34  and the at least one diffuser  36 . Furthermore, in an embodiment, the electric submersible pump  20  and the components of the electric submersible pump  20  have a geometry and configuration such that the fluid  44  when passing through the internal volume  42  is in fluid communication with the at least one impeller  34  and the at least one diffuser  36 . 
       FIGS. 4 and 5  illustrate embodiments of the at least one impeller  34  and the at least one diffuser  36  formed via additive manufacturing techniques. As shown in  FIGS. 4 and 5 , in an embodiment, each of the at least one impeller  34  and the at least one diffuser  36  are configured as a monolithic structure and comprised of a metal matrix composite  50 . As used herein, the term “metal matrix composite” is comprised of a metal matrix having a ceramic material dispersed therein (described presently). These materials are inherently designed to be sand tolerant and highly resistant to other contaminant materials that may result in erosion, abrasion, and corrosion to the pump stage components. More specifically, as illustrated, at least one or both of the cooperating impeller  34  and diffuser  36  are formed as a monolithic structure, and having a single solid, uniform material makeup. During the manufacture process, the monolithic structures may be manufactured by additive manufacturing processes, such Direct Metal Laser Melting (DMLM). In general, additive manufacturing techniques involve applying a source of energy, such as a laser or electron beam, to deposited powder layers in order to grow a part having a particular shape and features. 
     Referring now to  FIG. 6 , illustrated is a portion of a component according to an embodiment, and more particularly a portion of one of the impeller  34  or the diffuser  36  comprised of a metal matrix composite  50 . The metal matrix composite  50  is comprised of a metal matrix  52  and a ceramic material  54 . 
     The term “matrix” as used herein refers to a fine-grained material in which larger materials or objects are embedded. Further the term “metal matrix” as used herein refers to a metal material or a material comprised substantially of a metal material and capable of having other materials embedded therein. In one embodiment, the metal matrix  52  includes a metal in combination with a non-metal. In an embodiment, the metal matrix  52  includes a material selected from the group consisting cobalt, nickel, chromium, iron, copper and combinations thereof. In an embodiment, the metal matrix composite  50  includes the ceramic material  54  dispersed in the metal matrix  52  including chromium. 
     The term “ceramic” as used herein refers to an inorganic, non-metallic material having high hardness, high temperature strength, good electro-thermal insulation, and high chemical stability. Further, the term “ceramic” as used herein refers to a crystalline ceramic material or an amorphous ceramic material. In one embodiment, the ceramic material  54  includes a metal in combination with a non-metal. In one embodiment, the ceramic material  54  includes an oxide, a nitride, a boride, a carbide, a silicide, a silica, or a sulfide. In one embodiment, the ceramic material  54  includes a material selected from the group consisting of alumina, silica, aluminum silicate, zirconium oxide, mica, glass and combinations thereof. In an embodiment, the ceramic material  54  includes tungsten carbide (WC) dispersed in the metal matrix  52 . 
     As noted above, additive manufacturing techniques generally allow for construction of custom parts having complex geometries, curvatures, and features, such as at least one impeller  34  and the at least one diffuser  36  discussed herein. Accordingly, additive manufacturing may be used to construct portions of the submersible pump having a variety of shapes and features, such as the at least one impeller  34  and the at least one diffuser  36 . 
     Additive manufacturing may be particularly useful in the construction of at least one impeller  34  and the at least one diffuser  36  for the electric submersible pump, as the at least one impeller  34  and the at least one diffuser  36  may be constructed as a monolithic structure from high-strength materials that may be difficult to machine or tool using traditional methods. In addition, additive manufacturing techniques provide the capability to construct complex solid objects from computer models, without difficult machining steps. In general, additive manufacturing techniques involve applying a source of heat, such as a laser or electron beam, to deposited powder layers (e.g., layer after layer) in order to grow a part having a particular shape. 
     In the exemplary embodiment, the at least one impeller  34  and the at least one diffuser  36  are fabricated using an additive manufacturing process. Specifically, an additive manufacturing process known as direct metal laser sintering (DMLS) or direct metal laser melting (DMLM) is used to manufacture the monolithic components. Although the process is described herein as DMLS, one having ordinary skill in the art would understand that DMLM could also be used. Alternatively, the additive manufacturing method is not limited to the DMLS or DMLM process, but may be any known additive manufacturing process. This fabrication process eliminates joints that would typically be defined within the at least one impeller  34  and the at least one diffuser  36 , thus making them susceptible to contaminants. Rather, DMLS is an additive layer process that produces a component directly from a CAD model using a laser and a fine metal/composite powder. 
     The CAD model is sliced into thin layers, and the layers are then reconstructed layer by layer, such that adjacent layers are laser fused together. The layer thickness is generally chosen based on a consideration of accuracy vs. speed of manufacture. Initially, a steel plate is typically fixed inside the DMLS machine to serve as both a support and a heat sink. A dispenser delivers the powder to the support plate and a coater arm or blade spreads the powder on the plate. The machine software controls the laser beam focus and movement so that wherever the laser beam strikes the powder, the powder forms into a solid. The process is repeated layer by layer until the fabrication of the component, and in this particular instance, the at least one impeller  34  or the at least one diffuser  36  is completed. 
     It will thus be appreciated that using the DMLS method permits the monolithic design and construction of the at least one impeller  34  and the at least one diffuser  36  that were previously not producible in a reliable or economical manner. 
       FIG. 7  is a block diagram illustrating an embodiment of a method  60  for constructing the at least one impeller  34  and the at least one diffuser  36  using additive manufacturing techniques. The method  60  may be performed by an additive manufacturing system, with the acts described herein being performed by a computer. The method  60  includes defining a particular configuration (block  62 ). The configuration may be programmed into an additive manufacturing system by using a specialized or general purpose computer, for example. In some embodiments, the model may be for constructing the at least one impeller  34  or the at least one diffuser  36 , wherein each component has a complex shape. The defined configuration may include any of the shapes and features described above. In step  64 , a powder (e.g., a metal, ceramic, or composite powder) is deposited into a chamber, such as a vacuum chamber. Any of a variety of materials may be used in any suitable combination, including those described in detail above. In step  66 , an energy source, such a laser or electron beam, for example, is applied to the deposited metal powder. The laser or electron beam melts or otherwise consolidates the powder into a layer having a cross-sectional shape  68  corresponding to the configuration defined in step  62 . A computer or operator may determine whether the part is incomplete or complete, in step  708 . If the part is incomplete, then steps  64  and  66  are repeated to produce layers of consolidated powder having cross-sectional shapes  68  corresponding to the defined confirmation or model until construction of the part is complete. In other words, the energy source is applied to melt or otherwise consolidate each newly deposited powder layer until the final product is complete and the at least one impeller  34  and/or the at least one diffuser  36  having the defined configuration is produced. 
     Accordingly, disclosed is a novel electric submersible pump system, and more particularly, a novel electric submersible pump configured to provide improved contaminant tolerance and resulting increase in life span of the pump and pump components. Unlike contaminant tolerant coatings applied to metal alloy components, the lifespan made possible through the use of components manufactured by additive manufacturing techniques and configured as monolithic structures comprised of a metal matrix composite, as disclosed herein, is much longer and not limited by thickness of coating. The resulting system and pump minimize, if not eliminate, the effects of erosion, abrasion, and corrosion on component parts. 
     In one embodiment, the electric motor  22  is configured to operate a pump  20  in a borehole, or wellbore  12 , as indicated in  FIG. 1 . In one embodiment, the electric motor  22  is configured to operate an electric submersible pump  20  including the impeller  34  and the diffuser  36 , as indicated in  FIGS. 3-5 . In one particular embodiment, at least one of the impeller  34  and the diffuser  36  is configured as a monolithic structure, or component, comprised of the metal matrix composite  50  to allow long term operation of the at least one of the impeller  34  and the diffuser  36  in the presence of contaminants, such as sand, in the wellbore  12 . 
     In one embodiment, an ESP system  10  is provided. Referring to  FIG. 1 , in one embodiment, the ESP system  10  is configured to be installed in a wellbore  12 . In one embodiment, the ESP system  10  is configured to be installed in a geological formation  14 , such as an oilfield. In some embodiments, the ESP system  10  may be capable of pumping production fluids from a wellbore  12  or an oilfield. The production fluids may include hydrocarbons (oil) and water, for example. 
     In some embodiments, the ESP system  10  is installed in a geological formation  14 , such as an oilfield, by drilling a hole or a wellbore  12  in a geological formation  14 , for example an oilfield. The wellbore  12  maybe vertical, and may be drilled in various directions, for example, upward or horizontal. In one embodiment, the wellbore  12  is cased with a metal tubular structure referred to as the casing  16 . In some embodiments, cementing between the casing  16  and the wellbore  12  may also be provided. Once the casing  16  is provided inside the wellbore  12 , the casing  16  may be perforated to connect the geological formation  14  outside of the casing  16  to the inside of the casing  16 . In some embodiments, an artificial lift device such as the ESP system  10  of the present disclosure may be provided to drive downhole well fluids to the surface. The ESP system  10  according to some disclosed embodiments is used in oil production to provide an artificial lift to the oil to be pumped. 
     An ESP system  10  may include surface components, for example, an oil platform (not shown) and sub-surface components (found in the wellbore). In one embodiment, the ESP system  10  further includes surface components such as motor controller surface cables and transformers (not shown). In one embodiment, the sub-surface components may include pumps, motor, seals, or cables. 
     Referring again to  FIG. 1 , in one embodiment, an ESP system  10  includes sub-surface components such as the electric submersible pump  20  and the electric motor  22  configured to operate the pump  20 . In one embodiment, the electric motor  22  is a submersible two-pole, squirrel cage, induction electric motor. In one embodiment, the electric motor  22  is a permanent magnet motor. The motor size may be designed to lift the desired volume of production fluids. In one embodiment, the pump  22  is a multi-stage unit with the number of stages being determined by the operating requirements. In one embodiment, each stage of the electric submersible pump  20  includes a driven impeller  34  and a diffuser  36  which directs flow to the next stage of the electric submersible pump  20 . On one embodiment, the electric submersible pump  20  includes a first pump stage and a second pump stage. 
     In one embodiment, as indicated in  FIG. 1 , the electric motor  20  is further coupled to an electrical power cable  24 . In one embodiment, the electrical power cable  24  is coupled to the electric motor  22  by an electrical connector. In some embodiments, the electrical power cable  24  provides the power needed to power the electric motor  22  and may have different configurations and sizes depending on the application. In some embodiments, the electrical power cable  24  is designed to withstand the high-temperature wellbore environment. 
     Further, as noted earlier, in one embodiment, the electric submersible pump  20  includes a housing  40 , the impeller  34  and the diffuser  36 , the impeller  34  and the diffuser  36  are disposed within the housing  40 , as indicated in  FIG. 3 . As noted earlier, the housing  40 , the impeller  34  and the diffuser  36  define the internal volume  42  within the housing  40 , said internal volume  42  containing the fluid  44 , as indicated in  FIG. 3 . 
     In the disclosed embodiments, the impeller  34  and the diffuser  36  are configured as monolithic structures manufactured utilizing additive manufacturing techniques and comprised of the metal matrix composite  50 , thus enabling operation in the presence of damaging contaminants, where the system  10  is exposed to these types of conditions. The metal matrix composite  50  advantageously allows for the electric submersible pump  20 , and more particularly the impeller  34  and the diffuser  36  to continuously operate in environments in which contaminants are present. 
     This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.