Abstract:
The present invention provides an electric submersible pumping assembly that includes an encapsulated pumping device containing a pump, an electric submersible motor, a sealing device at the top, and an opening device at the bottom. The lubricant-filled, initially sealed, encapsulated pumping device allows the pump and motor to be run in the wellbore without contamination and be left intact until operated.

Description:
FIELD OF INVENTION 
     The present invention relates generally to the field of electric submersible pump assemblies, and more particularly, but not by way of limitation, to an electric submersible pump assembly having an encapsulated submersible motor and pump. 
     BACKGROUND OF INVENTION 
     In oil wells and the like from which the production of fluids is desired, a variety of fluid lifting systems have been used to pump the fluids to the surface. It is common to employ various types of downhole pumping systems to pump the subterranean formation fluids to surface collection equipment for transport to processing locations. 
     One such prior art pumping system is a submersible pumping assembly which is supported in the wellbore, the submersible pumping assembly having a pump and a motor to drive the pump to pressurize and pass the fluid through production tubing to a surface location. A typical electric submersible pump assembly includes a submersible pump and an electric motor that are directly in contact with the wellbore fluids. Submersible pumping assemblies are often placed in the wellbore months or years before use, causing extended exposure to scale and corrosion. Additionally, motor lubricant can suffer breakdowns such as the loss of motor oil light ends during this period of inactivity. Long periods of inactivity have become more communon, particularly in deep water drill locations where it is expensive to rework a well. The cost of reworking an offshore well to add a submersible pump can be so expensive as to make the remaining reserves uneconomical to produce. Thus, there is a need for a method of effectively protecting the submersible pumping assemblies that are currently being placed in the wellbore and keeping the submersible pumping assemblies free from contamination. 
     SUMMARY OF THE INVENTION 
     An electric submersible pumping assembly includes, a first sealing device, a first opening device and an encapsulated pumping device. The encapsulated pumping device is disposed between the first sealing device and the first opening device. The encapsulated pumping device includes a pump assembly, a motor assembly and a device body. The motor assembly includes a seal section operably connected to the pump assembly. The device body forms a chamber around the pump assembly and the motor assembly. The encapsulated pumping device transmits production fluids when the first sealing device and the first opening device are open. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a diagrammatical, partially detailed, elevational view of an electric submersible pumping assembly with an encapsulated pumping device constructed in accordance with the present invention. 
     FIG. 2 is a diagrammatical representation in perspective of the encapsulated pumping device of FIG.  1 . 
     FIG. 3 is a diagrammatical, partially detailed, elevational view of the encapsulated pumping device of FIG.  1 . 
     FIG. 4 is a diagrammatical, partially detailed, elevational view of the upper portion of the encapsulated pumping device of FIG.  1 . 
     FIG. 5 is a diagrammatical, partially detailed, elevational view of the lower portion of the encapsulated pumping device of FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     Referring generally to the drawings, and in particular to FIG. 1, shown therein is an electric submersible pumping assembly  10  constructed in accordance with the present invention. The electric submersible pumping assembly  10  has an encapsulated pumping device  12  for use in a wellbore  14  below ground level or surface  16  and extending through a producing zone  18 . Located above the encapsulated pumping device  12  is a first sealing device  20  which can be a pressure sensitive disc, retrievable plug, control valve or other similar device capable of staying closed for a period of time and then being opened. The first sealing device  20  can be mechanically, hydraulically or electrically actuated. Methods of actuating the first sealing device  10  can include use of a pressure sensitive disc or a mechanically actuated plug that is retrieved by wireline or coil tubing. 
     The electric submersible pumping assembly  10  also has a first opening device  22  below the encapsulated pumping device  12  that will allow produced fluids to enter the encapsulated pumping device  12  when operating the encapsulated pumping device  12 . The first opening device  22  can be operated via a control line  24 , and can be hydraulically or electrically actuated. Hydraulic power used to actuate the first opening device  22  can be provided by pump discharge pressure. 
     The encapsulated pumping device  12  has an upper end portion  26  and a lower end portion  28 . Attached to the lower end portion  28  is a tail pipe  30  which can be a piece of standard tubing. Produced fluid  32 , also known as the production stream  32 , can enter the tail pipe  30 , be pressurized, and produced to the surface  16  through production tubing  34 . The tail pipe  30  can have a second sealing device  36  like the first sealing device  20  described above. The second sealing device  36  can act as a back up to a first opening device  22 . 
     The production tubing  34 , above the encapsulated pumping device, can have a second opening device  38  that will allow produced fluids to enter production tubing  34  prior to operating the encapsulated pumping device. The second opening device  38  can include perforations, a sliding sleeve, control valve, or another device that is capable of opening and closing the tubing. The second opening device  38  can be hydraulically, electrically or mechanically actuated such as by wireline or coil tubing. As with the first opening device  22 , the second opening device  38  can be manipulated by hydraulic power provided by pump discharge pressure. There can also be an optional packer  40  positioned above the encapsulated pumping device  12 . 
     FIG. 2 shows the encapsulated pumping device  12  for use in the wellbore  14 . The encapsulated device  12  is in fluid communication with the surface  16  and the production zone  18  (shown in FIG.  1 ). The encapsulated pumping device  12  has a device body  44  forming a chamber  46 , the upper end portion  26  and lower end portion  28  being integral portions of the device body  44 . The upper end portion  26  is in fluid communication with a pup joint  48  and a device outlet  52 . The upper end portion  26  abuts an upper connection device  54  via a pressure seal  56 . The upper connection device  54  provides a means of hanging the encapsulated device  12  by the use of the pup joint  48  screwed into the upper connection device  54 . The production tubing  34  is attached to the pup joint  48 , allowing fluid communication with the surface  16 . 
     The lower end portion  28  abuts a lower connection device  58  and is in fluid communication with a device inlet  60 . The lower connection device  58  provides a connection for tail pipe  30 . Supported inside the device body  44  is a pump assembly  62  which has a multistage submersible pump  64  with a pump inlet  66  in fluid communication with the production zone  18  via inlet device  60 . The pump  64  also has a pump outlet  68 , shown here in a pump discharge head  69 , which is in fluid communication with the device outlet  52 . 
     The encapsulated electric pumping device also includes an electric submersible motor assembly  70  that drives the multistage submersible pump  64 . This motor assembly  70  includes an electric submersible motor  72  supported in the device body  44 . A seal section  74  is disposed between the pump assembly  62  and the motor assembly  70 . The electric submersible motor  72  is produced by companies such as the assignee of the present invention under model numbers WG-ESP TR-4 and TR-5. The device body  44  also includes a means of power transfer, such as a power cable  76 , for transferring power from a power source to the electric submersible motor assembly  70  through a power connector  78  with a pressurized seal. Special provisions can be made in the upper connection device  54  to install a feed-through system for the power cable  76 . Such systems provide means of running cable inside encapsulated systems by providing high pressure sealing connections. These systems, such as ESP No. 145395, are readily available from vendors such as Quality Connections, Inc. in Foxboro, Mass. 
     FIG. 3 shows the encapsulated pumping device  12  of the present invention in more detail. The device body  44  can be made up of a series of casing joints screwed together. The power cable  76  has been removed to make the components of the encapsulated pumping device  12  easier to show. 
     One skilled in the art will recognize that the encapsulated pumping device  12  can have additional components such as a sensor  80  located adjacent the motor  72  for sensing mechanical and physical properties, such as vibration, temperature, pressure and density, at that location. This sensor, such as the commercially available Promore MT12 or MT13 models available from Promore Engineering, Inc. in Houston, Tex., can also be located adjacent to the pump  64 , the motor  72 , the surface  16  or other critical locations. One skilled in the art will understand that one or more of these sensors would be helpful to the operation of the encapsulated pumping device  12  in ways such as using the feedback to optimize production by regulating the encapsulated pumping device  12  and its various components. An example would be to use pump pressure feedback to actuate downhole control valves and operate the opening devices and the sealing devices. It is also well known that the use of a centralizer  82 , as shown in FIG. 3, can optimize performance of the pumping device. 
     FIG. 4 shows the upper connection device  54  of the encapsulated pumping device  12 . The upper connection device  54  of the present invention is preferably a hanger with a hanger body  84  forming a first chamber  86  and a second chamber  88 . The upper connection device  54  has an upper surface  90  and a lower surface  92 . The hanger body  84  of the upper connection device  54  is supported by the device body  44  with fasteners  94  that connect an opening  96  in the device body  44  and an opening  98  in the hanger body  84 . 
     The first chamber  86  has a connection, which in the present invention is a threaded connection  100 , capable of supporting the pump assembly  62  in the hanger body  84 . The second chamber  88  has a connection, which in the present invention is a threaded connection  102 , capable of supporting a cable connection in the hanger body  84 . The hanger body  84 , of the present invention, has the pressure seal  56  disposed between the device body  44  and the hanger body  84 . The pressure seal  56  is isolates the pressure within the encapsulated pumping device  12 . 
     FIG. 5 shows the lower connection device  58  of the encapsulated pumping device  12 . The lower connection device  58  of the present invention has a base body  104  forming a chamber  106  having an upper surface  108  and a lower surface  110 . The base body  104  of the lower connection device  58  is supported by the device body  44 . The device body  44  can be attached by welding to the base body  104 . The device body  44  can also be held by fasteners, such as screws, or a design feature, such as a lip, coupled with external forces. The base body  104  has an outer surface  112  and an inner surface  114  such that the outer surface  112  has a connection means, such as threads  116 , capable of supporting other objects, such as joints of tubing or other devices. The lower surface  110  is in fluid communication with the device inlet  60  for accepting the flow of production stream  32 . 
     Tail pipe  30  can be screwed onto the base  104  using the threads  116  of the lower connection device  58  and this tubing can sting into a second packer (not shown). A control valve can be installed with the packer so that when the control valve actuates, the produced fluids  32  communicate with the pump  64 . 
     It will be clear to those skilled in the art that more than one encapsulated pumping device  12  could be used in one wellbore. It will also be clear that additional separators, pumps and/or motors can be used in conjunction with the encapsulated pumping device  12  as well as permanent and semipermanent packers. 
     The electric submersible pumping assembly  10  with an encapsulated pumping device  12  can be incorporated as one part of a larger pumping device to perform other essential downhole functions. For instance, a gas separator can be attached to the electric submersible pumping assembly  10  with an encapsulated pumping device  12  to handle excess gas before the gas passes through a separator. 
     The encapsulated pumping device  12  is initially lubricant-filled and sealed, thereby increasing the life expectancy, efficiency, and reliability of the pump and motor portions thereof. The choice of a fluid to be run in the encapsulated pumping device  12  involves a number of considerations related to the storage and operation of the encapsulated pumping device  12 . For instance, if a mechanical shock is anticipated prior to start up, a high viscosity fluid would be chosen to minimize the effects of the mechanical shock on the encapsulated pumping device  12 . 
     The production tubing  34 , also known as discharge tubing, can be blocked with a sealing device, such as a rupture disc, a retrievable plug or similar device, before the encapsulated pumping device is run in the wellbore  14 . The tail pipe  30 , also known as intake tubing, can be blocked with a conventional sliding sleeve, as discussed above, before the encapsulated pumping device is run in the wellbore  14 . 
     Prior to operating the encapsulated pumping device, the production stream  32  enters the wellbore  14  from the production zone  18  and flows past the encapsulated pumping device  12 . The production stream  32  is produced to the surface  16  through the annulus and enters the production tubing  34  through the second opening device  38 , which can be a sliding sleeve, located above the sealing device  20 . The optional packer  40  can be added to prevent the fluid from entering the casing annulus for a variety of reasons that would be well known to one skilled in the art. At this time the lubricant filled sealed encapsulated pumping device  12  remains protected from wellbore contaminants. 
     Before the pump is operated, the second opening device  38  is closed and the first opening device  22  is opened using hydraulic or electrical power. The motor powered pump  64  is started, pressurizing the encapsulated device  12  to a preset level, so that the first sealing device  20  ruptures allowing fluids to be pulled into the encapsulated pumping device  12  through the tail pipe  30  and the first opening device  22 . Cooling of the motor  72  can be achieved by maintaining a minimum flow rate velocity of 1 ft/sec of the production stream  32  past the motor  72 . 
     In another embodiment, the encapsulated pumping device  12  is run in the hole with production tubing  34  that has a first sealing device, such as a rupture disc or similar device, and tail pipe that has a second sealing device  36 , which can also be a rupture disc. The method of rupturing the first sealing device  20  is to pressure up on tubing  34  from the surface  16  to cause a pressure differential across the disc sufficient to burst the rupture disc. This pressure could also rupture the second sealing device  36  located below the encapsulated pumping device  12 . Other surface activated techniques, as are known by those skilled in the art, could also be used to open the first sealing device  20  and the second sealing device  36 . These include, for example, the use of wireline or coil tubing activated techniques used to open a mechanically actuated plug. One skilled in the art would be aware of other mechanical, hydraulic or electrical methods of opening the first sealing device  20  and the second sealing device  36 . 
     In operation, when the production stream  32  enters the wellbore  14  the fluid is drawn by the motor powered pump  64  to the pump intake section  66 , enters the pump  64 , and is pressurized and pumped to the surface  16 . If there is significant gas present in the fluid stream, it can be advantageous to use a gas separator-type pump intake or other known methods to handle the gas expansion. 
     It is clear that the present invention is well adapted to carry out the objectives and to attain the ends and advantages mentioned as well as those inherent therein. While the present invention has been described in varying detail for purposes of the disclosure, it will be understood that numerous changes can be made which will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention disclosed in the above text and in the accompanying drawings.