Patent Publication Number: US-10309209-B2

Title: Electric submersible pump suction debris removal assembly

Description:
FIELD OF THE INVENTION 
     The field of the invention is artificial lift systems and more particularly an independently supported and selectively removable modular suction debris removal device for an electric submersible pump (ESP). 
     BACKGROUND OF THE INVENTION 
     Wells that lack the formation pressure to produce to a surface location have used an ESP to boost pressure sufficiently for that purpose. It is desirable to exclude debris from the suction of the ESP and various schemes attached to the suction of the ESP have been proposed in the past. Some examples of such designs are U.S. Pat. No. 7,703,508 where an intake screen has a bypass feature if it clogs with debris and U.S. Pat. No. 7,503,389 FIG. 8 showing concentric screens supported by the suction connection on the ESP. U.S. Pat. No. 6,216,788 shows using a sand separator that includes a hydrocyclone and a bypass line with an intention of using pump pressure to get the captured sand or debris to the surface. Modular porous suction filters supported by the ESP are shown in US 2015/0064034. Suction filtering is mentioned in passing for an ESP in U.S. Pat. No. 9,097,094. A seabed mounted ESP and inlet screen is described in U.S. Pat. No. 8,961,153. 
     A known debris removal and retention device made by Baker Hughes Incorporated and known in the industry as a VACS tool is shown in FIG. 1 of U.S. Pat. No. 7,472,745. This tool typically uses an eductor powered by pumped flow from a surface location to draw debris laden fluid into an intake pipe whereupon the debris is deflected into a surrounding annular debris retention space and the fluid stream continues up the tool through a screen and is drawn by the eductor to outside the tool housing whereupon some flow recycles back down the hole and the rest flows uphole. 
     The currently available ESPs have limits to the weight they can support not only for the weight of the filtration equipment but also the added weight of the captured debris. Some designs have resorted to simply dumping captured debris into the rat hole but this is merely a stopgap solution still limited by the limited weight that can be supported directly from the ESP. The present invention supports a debris removal assembly from a retrievable packer or anchor or other support in the borehole that can be sealed to the borehole wall to allow heavier structures that can capture debris so that the captured debris can be removed from the borehole when the packer is retrieved. A modular design for the debris removal assembly allows selection of the needed volume for debris retention for the anticipated debris load. The ESP provides the motive force to draw fluid into the debris removal assembly which has aspects of the VACS tool but does not use the jet bushing of the VACS tool since the application is on a pump suction as opposed to the eductor based VACS design of the past. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined by the appended claims. 
     SUMMARY OF THE INVENTION 
     An electric submersible pump (ESP) is coupled with a spaced apart debris removal assembly that is independently supported from a retrievable packer. The debris removal assembly is modular to accommodate required debris capacity by adapting the overall length, as well as changing the dimensional diameters for proper flow dynamics, and retains to accommodate required debris capacity by adapting the overall length, as well as changing the dimensional diameters for proper flow dynamics, and retains to accommodate required debris capacity by adapting the overall length, as well as changing the dimensional diameters for proper flow dynamics, and retains and retains the captured debris for subsequent removal from the well with the retrievable packer. The modular design allows for the addition of large debris collections and separation from fine debris collection. The ESP suction draws in well fluids through the debris retention device. The ESP can be pulled to allow removal of the retrievable packer with the debris removal assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of the assembly of an ESP with a single module of a debris removal device; 
         FIG. 2  shows the view of  FIG. 1  with stacked modules for debris removal; 
         FIG. 3  shows the details of a debris removal module and the flow therethrough. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  an ESP  10  is supported in a borehole  12  on a tubing string  14  shown in  FIG. 2 . A retrievable packer  16  supports at least one debris removal module  18 . Module  18  has an inlet tube  20  topped by an open deflecting cap  22  such that debris  24  settles in an annular shaped retention volume  26  that surrounds inlet tube  20 . Flow continues upwardly toward ESP  10  but has to pass through a screen  28  where debris that is finer than  24  will also be stopped as the filtered fluid goes through to either another stage as shown schematically in  FIG. 2  or through the packer  16  and up to the ESP  10 . 
     In  FIG. 3  arrow  30  shows the incoming debris laden flow into the inlet tube  20  which can be centralized with radially extending members  32  with debris entering retention volume  26  able to pass between the extending members  32 . As shown in  FIG. 2  the modules  18 ,  18 ′ and  18 ″ can be stacked in series in any desired number. The screen  28  in each module can have the same opening size or the opening size can get smaller progressively as the flow gets closer to the ESP  10  as debris drops out in each successive stage. The number of modules can be varied depending on the debris capacity that is needed. However many modules are envisioned they are run in and supported when the packer  16  is set so that their empty weight plus the weight of captured debris is not on the ESP  10  that has limited capability to support weight. Simply turning on the ESP  10  draws debris laden flow into the inlet tube(s)  20 . Each module  18  can be directly threaded to an adjacent module directly or through an intervening coupling or by using a quick connect. 
     Those skilled in the art will appreciate that without loading weight on the ESP  10  that it may not be able to support debris collection volume can be tailored to the application by selecting the number and length of modules and connecting them preferably directly or indirectly with a threaded connection. The assembled modules are supported by a retrievable packer that allows removal of all the modules with the packer and the captured debris. The life of the ESP or any other piece of downhole equipment can be lengthened by effective debris removal before well fluids enter a tool with moving components and close clearances that can be damaged by uncaptured debris. The use of a modified design from a traditional VACS tool allows economies of production as the jet bushing from a known VACS tool is removed in favor of modules that can be connected is series each of which features an inlet tube for debris laden flow surrounded by a collection chamber. The inlet tube has a top deflector to direct debris into the chamber while the suction flow continues toward the ESP and passes through a screen before exiting each module. The particles caught on such screens can also drop into the annular shaped retention volume with debris deflected into such volume from the inlet tube. Debris of progressively smaller diameter can be removed in sequence in a stack of such modules. The modules can be connected with threaded connections or quick snap together connections for rapid assembly or disassembly after use. While use with an ESP is a preferred application, use of an independently supported debris removal assembly can be deployed with a variety of other tools having components that would be adversely affected by passing borehole debris if such debris were not removed. Preferably, the ESP can be removed separately from the retrievable packer. Optionally the support string for the ESP can be configured to latch with a linkage onto the packer to release and retain it so that the ESP and the packer with the debris removal modules can be removed in a single trip without the ESP needing to support the weight of the debris laden modules. The debris collection chamber in each module can also have a screened drain hole or holes to avoid having to lift the weight of well fluid during the removal process. 
     The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: