Abstract:
A filter sub apparatus comprising a housing configured to contain a filter and a bypass mechanism is provided. The bypass mechanism may be actuated upon debris buildup on the filter resulting in a load applied to the bypass mechanism rising above a predetermined lower level. A method to prevent chemical injection process failures may also be provided. The method may comprise the steps of providing a filter sub prior to a check valve. The filter sub may include a filter and a bypass mechanism. Another step may be passing fluid through the filter. In addition, the steps may also include containing at least some debris on a side of the filter such that the debris is prevented from reaching the check valve. A further step may be actuating the bypass mechanism after the debris builds up to a level in which a resulting load applied to the bypass mechanism exceeds a lower limit.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/045,139, filed Apr. 15, 2008, the contents of which are herein incorporated by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     Embodiments of the present invention generally relate to inline filter devices used for filtering flowing fluid and more particularly to clog tolerant inline filter devices with a bypass feature such as may be used in a chemical injection system. 
     2. Description of the Related Art 
     The following descriptions and examples are not admitted to be prior art by virtue of their inclusion in this section. 
     In typical wellbore operations, conventional chemical injection systems deploy selected chemicals in oil and gas wells for the purposes of controlling tubing corrosion, paraffin buildup, hydrate plugging, etc. Down-hole injection systems are typically comprised of a fluid reservoir, a surface pumping system, plumbing to the wellhead or sub-sea umbilical, a capillary tube attached to the exterior of the production tubing string, a ported mandrel installed in the tubing string, and a complement of back-check valves that prevent down-hole fluid ingression into or through the injection system. 
     Chemical injection systems generally consist of an injection line run from the surface to a side pocket mandrel in the production tubing string. The mandrel is either equipped with internal check valves or attached to a cartridge which contains check valves that allow injection of treating chemicals from the surface while retaining tubing (reservoir) pressure. 
     By design, all check valves are inherently sensitive to debris. As treating chemicals are pumped from the surface any debris suspended in the treating chemicals will be forced to travel through the check valves. Often debris will be too large to travel through the check valves and may become lodged in the valve. This debris can keep the check valve from properly closing. If the check valves are unable to close, the pressure and fluid in the production tubing will be able to communicate with the injection line, thereby contaminating the injection fluid and otherwise preventing effective chemical injection of a well. In many applications, the use of chemical injection is critical to production. However, an improperly functioning chemical injection system may result in the removal of the completion. 
     In most cases debris related failures in chemical injection systems occur almost immediately after installation. Generally debris is either introduced during the termination of injection lines or it may be present in pumps, tanks, or lines prior to injection. As injection begins the debris is quickly circulated downhole to the check valves, resulting in immediate initial failures. The contamination level present in the treating chemicals of a chemical injection process is generally very low. This low level can be further regulated through the use of surface filtration. As such, if the valves are not damaged due to start up debris, the probability of future debris related failures is relatively low. What is needed is a cost effective way to filter fluid while providing a contingency in cases in which the filter becomes clogged with debris. 
     SUMMARY 
     In accordance with one embodiment of the invention, a filter sub apparatus comprising a housing configured to contain a filter and a bypass mechanism may be provided. The bypass mechanism may be actuated upon debris buildup on the filter resulting in a load applied to the bypass mechanism rising above a predetermined lower level. 
     In accordance with another embodiment of the invention, a method to prevent chemical injection process failures may also be provided. The method may comprise the steps of providing a filter sub prior to a check valve. The filter sub may include a filter and a bypass mechanism. Another step may be passing fluid through the filter. In addition, the steps may also include containing at least some debris on a side of the filter such that the debris is prevented from reaching the check valve. A further step may be actuating the bypass mechanism after the debris builds up to a level in which a resulting load applied to the bypass mechanism exceeds a lower limit. 
     Other or alternative features will become apparent from the following description, from the drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying drawings illustrate only the various implementations described herein and are not meant to limit the scope of various technologies described herein. The drawings are as follows: 
         FIG. 1  is a cross-sectional side view of a filter sub in accordance with an embodiment of the claimed invention; 
         FIG. 2  is an enlarged portion of the cross-sectional side view of  FIG. 1 ; 
         FIG. 3A  is a partial cross-sectional side view of a filter sub in a non-bypass configuration in accordance with an embodiment of the claimed invention; 
         FIG. 3B  is a partial cross-sectional side view of the filter sub of  FIG. 3A  in a bypass configuration in accordance with an embodiment of the claimed invention; and 
         FIG. 4  is a cross-sectional side view showing the application of a resetting tool in a filter sub in accordance with an embodiment of the claimed invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. In the specification and appended claims: the terms “connect”, “connection”, “connected”, “in connection with”, “connecting”, “couple”, “coupled”, “coupled with”, and “coupling” are used to mean “in direct connection with” or “in connection with via another element”; and the term “set” is used to mean “one element” or “more than one element”. As used herein, the terms “up” and ““down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”; “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. 
     Embodiments of the claimed invention may have multiple applications and uses. However, in the interest of simplifying the description, most embodiments will be described as being used in conjunction with downhole chemical injection systems as a non-limiting example. Embodiments of a filter sub may be adapted for use in other hydraulic or fluid systems that are sensitive to debris. 
     Embodiments of a filter sub may be made up in an injection line in the annular space between a casing and production tubing, for example, such as provided directly above a chemical injection valve. The filter sub may comprise externally testable hydraulic connectors. All treating chemicals may initially pass through the filter sub before reaching check valves in the chemical injection mandrel. The filter sub may include a filter or screen that is configured to capture debris capable of impeding check valve functionality. In cases in which the filter becomes plugged, the pressure required to pump fluid across the filter increases. To ensure that the chemical injection is not interrupted or otherwise impeded, an automatic filter bypass may be triggered if the increase in the pressure exceeds a predetermined level. After the filter has been bypassed, the debris that created the plug will generally be retained in a sump located above the filter. The bypass may allow the fluid to continue to flow through the filter sub, thereby facilitating the continuation of the injection process. 
     Referring generally to  FIG. 1 , an illustrative embodiment of a filter sub  10  is shown in a cross-sectional side view. The filter sub  10  may comprise an upper and lower hydraulic dry mate connector  100  (HDMC) respectively coupled to an upper housing  200  and a lower housing  300 . The upper housing  200  may be coupled to the lower housing  300  via a filter housing  400 . Although three separate housings are shown in this exemplary embodiment ( 200 ,  300 , and  400 ), other embodiments of the invention may not be limited to this configuration. Less than three or more than three housings may be used depending upon manufacturing and machining techniques. In addition, the three housings ( 200 ,  300 , and  400 ) and the upper and lower HDMCs  100  may be coupled together via a variety of techniques not limited to the threaded or welded connections shown. Other techniques may include press, snap fit, or interlocking components, or chemical adhesive, among others. In some cases, the three housings ( 200 ,  300 , and  400 ) may be substantially cylindrical in shape and enclose a central bore for fluid flow. 
     The filter housing  400  may comprise an inner sleeve  500  and a filter  600 . One end of the inner sleeve  500  may be substantially sealed to the interior of the intermediate filter housing  400  via one or more seals  700  (only one seal is shown in this non-limiting example). Another end of the inner sleeve  500  may be releasably coupled with a restraint feature  450 . The restraint feature  450  may be coupled with engaging features of the inner sleeve  500 , such as collet fingers (detailed later) for example. The filter  600  may be coupled with the interior bore of the inner sleeve  500  through a variety of non-limiting techniques. 
     Turning now to  FIG. 2 , this figure illustrates an enlarged portion of the filter housing  400  in a cross-sectional side view in order to more easily identify exemplary aspects of an embodiment of the claimed invention. As shown in the figure, inner sleeve  500  is contained within the filter housing  400 . Included within the inner sleeve  500  is the filter  600 . In some embodiments, the filter  600  may be a metallic screen sized to capture any debris that can not pass freely through standard chemical injection check valves. The filter  600  may be equipped with external threads configured to engage internal threads in the inner sleeve central bore  510 . In some embodiments, prior to installation of the filter  600 , the threads on both the filter  600  and the inner sleeve  500  may be coated with a high temperature and high strength chemical formula, such as Loctite® 272 for example. In other embodiments, the filter  600  may comprise non-metallic, permeable, or coated materials configured to accommodate the expected flow rate of the fluid through the filter sub  10 . Alternatively, one or more additional components may be used to fix the filter  600  in relation to the inner sleeve  500  (e.g., such as a retention ring or set screws, among others), while in other embodiments, the filter  600  may be fixedly attached directly to the inner sleeve  500 . The filter  600  may be used for the life of the inner sleeve  500  or may be configured to be replaceable. 
     One or more seals  700  may be used to establish a pressure tight seal between the inner sleeve  500  and the filter housing  400 , thereby forcing fluid such as injected chemicals to pass through the central bore  510  of the inner sleeve  500  and the filter  600 . Debris that can not pass through the filter  600  may be retained in the central bore  510  of the inner sleeve  500  on the upstream side of the filter  600  (the top as shown in  FIG. 2  for an injection system). The central bore  510  above the filter  600  may serve as a debris sump. The one or more seals  700  may be in the form of an o-ring. The seal  700  may provide a substantially fluid tight seal between the outer circumference of one end of the inner sleeve  500  and the inner circumference of the filter housing  400 . 
     In addition to the one or more seals  700 , one end of the inner sleeve  500  may comprise an inner sleeve protruding interface  520 . The inner sleeve protruding interface  520  may be configured to abut against a corresponding feature in the filter housing  400 , such as a filter housing protruding interface  420 , although embodiments of the invention may not be limited to this example. In this case, both the inner sleeve and filter housing protruding interfaces  520  and  420  may be configured to be substantially conical in shape. In other cases, the protruding interfaces  520 ,  420  may be configured to provide a secondary or primary seal between the inner sleeve  500  and the filter housing  400 . During assembly, the inner sleeve protruding interface  520  may provide an axial limit to the insertion of the inner sleeve  500  into the filter housing  400 . This limit should be designed such that the engaging features of the inner sleeve  500  are able to be coupled to the engaging features of the filter housing  400 . 
     In this illustrative embodiment, the inner sleeve  500  comprises one or more collet fingers  530  including raised finger profiles  540 . The raised finger profiles  540  may be configured to engage with raised restraint profiles  440  provided in the restraint feature  450  (e.g., such as a retaining ring, among other examples of restraint features). The engagement between the finger profiles  540  and the restraint profiles  440  may be configured to release at a desired axial load range. Of course, other embodiments may not be limited to this configuration for providing a releasable coupling between the inner sleeve  500  and the filter housing  400 . For example, snap rings, shear screws, and/or increased frictional surfaces, among others, may be used to releasably retain the inner sleeve  500  in axial position with the filter housing  400  until subjected to an axial load exceeding a predetermined amount. Alternatively, the housing  400  may comprise the collet fingers and the inner sleeve  500  may comprise a restraint profile. Although the profiles of the collet fingers  530  and the restraint feature  450  are both shown in this illustrative embodiment as raised protrusions, this should be considered as a non-limiting example. One or both of the components may contain a recessed profile, a combination of profiles, or other methods designed to releasably retain the inner sleeve  500  in axial position relative to the filter housing  400  until an axial load limit applied to the inner sleeve  500  is exceeded. 
     The inner sleeve  500  may surround an inner sleeve central bore  510  to filter fluid flowing there through. (See  FIG. 3A ) In the event that a large amount of debris  900  (see  FIG. 3B ) is captured by the filter  600 , pressure may build up on the inner sleeve  500 , thereby applying an axial load to the component. When the load exceeds a predetermined lower limit, the finger profiles  540  of the inner sleeve  500  may be disengaged from the restraint profiles  440  of the filter housing  400 . As the inner sleeve  500  is released, the one or more seals  700  on the inner sleeve  500  may be pulled out of the seal bore on the housing  400 . The inner sleeve  500  may then be free to move axially downstream until it occupies a lower space  350 . Upon reaching the lower space  350 , the interaction between the ends of the collet fingers  530  and the configuration of the lower space  350  may prevent or inhibit further axial movement of the inner sleeve  500 . The debris  900  that created the original plug may be retained in the sump or inner sleeve central bore  510  above the filter  600 . With the one or more seals  700  disengaged from the seal bore of the interior circumference of the housing  400 , the treating chemicals would then be free to flow around, or bypass, the inner sleeve  500 . 
       FIG. 3A  shows an embodiment of the invention in an initial position. The arrow demonstrates the initial pre-bypass flow of the fluid through the central bore  510  of the inner sleeve  500  and filter  600  to exit out of the bottom of the device.  FIG. 3B  shows the embodiment of  FIG. 3A  when the inner sleeve  500  is in a bypass position due to a collection of debris  900  on the upstream side of the filter  600 . As shown by the arrows in  FIG. 3B , the inner sleeve  500  moves to a location within the filter housing  400  such that fluid is able to flow around the inner sleeve  500 , as opposed to through it. Of course, the fluid is no longer completely subjected to the screening effect of the filter  600  while in the bypass configuration. However, the debris  900  collected in a sump formed by the inner sleeve central bore  510  above the filter  600  is not released into the fluid stream during the activation of the bypass mechanism. In most cases, such as in a chemical injection process in which the majority of debris  900  is present and collected during the initial stages of the injection process, the bypass configuration should not result in a large amount of additional debris passing to the check valves of the system. 
     Referring generally to  FIG. 4 , after assembly a completed filter sub  10  there may be instances in which the assembly is dropped or otherwise subjected to a force that releases the engagement between the inner sleeve  500  and the filter housing  400 , placing the filter sub  10  in a bypass configuration. The inner sleeve  500  may be reset to an initial, non-bypassed position in an assembled device through the use of a resetting tool. The resetting tool may comprise a coupling device  950  and a resetting device  955 . The coupling device  950  may be threadably attached to the lower housing  300  and provide a threaded orifice to attach and support the resetting device  955 . The resetting device  955  may then be threaded into the filter sub  10  until one end of the resetting device  955  engages the filter  600 . By rotating the resetting device  955  relative to the coupling device  950 , the end of the resetting device  955  may axially translate the inner sleeve  500  relative to the filter housing  400  until there is engagement between the collet fingers  530  and the restraint feature  450  (see  FIG. 2 ). At this point, the one or more seals  700  may sealingly couple the inner sleeve  500  to the seal bore of the filter housing  400  such that fluid will be directed to flow through the central bore  510  and filter  600  of the inner sleeve  500 . 
     In an alternative embodiment, a rupture disc (not shown) may be incorporated in the upper housing  200  (see  FIG. 1 ). The rupture disc may enable the testing of the integrity of the injection line and hydraulic connectors above the disc prior to and during installation. 
     Both the upper and lower housings  200 ,  300  (see  FIG. 1 ) may have female profiles configured to couple with appropriate hydraulic connectors, such as the HDMC  100 , among others. The HDMC  100  may create a seal between the fluid lines (not shown) and the filter sub  100 . 
     The filter sub  10  (see  FIG. 1 ) may protect the check valves or other downhole tools from debris related failures, such as with the check valves in downhole chemical injection applications. The system may be completely autonomous and may not require an intervention. The filter  600  (see  FIG. 1 ) may be bypassed in the event that it becomes clogged. The bypass mechanism may not reintroduce debris into the system. In the even that the filter  600  is bypassed, the debris that created the plug may be retained in the central bore  510  of the inner sleeve  500  (see  FIG. 2 ). The system may be re-settable at the surface. In some embodiments, the collet fingers  530  (see  FIG. 2 ) on the lower end of the inner sleeve  500  may be replaced with a resilient mechanism such as a spring to allow the inner sleeve  500  to reset downhole. 
     While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations there from. It is intended that the appended claims cover such modifications and variations as fall within the true spirit and scope of the invention.