Patent Publication Number: US-8967265-B2

Title: Flow control apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to United Kingdom Patent Application No. GB1012268.7 filed on Jul. 22, 2010, the contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     This invention relates to a flow control apparatus. More particularly, the invention relates to a flow control apparatus for use in a wellbore and a method of cleaning a flow control apparatus in a wellbore. 
     BACKGROUND TO THE INVENTION 
     In unconsolidated formations created for the extraction of oil and gas, horizontal and deviated wells may be provided with integrated sand screens and inflow control device (ICD) completions, such as those described in GB2448069. Such wells are usually drilled using a drilling mud containing solids for bridging purposes and to prevent fluid loss into the formation. Once the well has been drilled, the drilling mud is replaced with a non-damaging fluid, called Drill In Fluid (DIF), which is cleaner than the conventional drilling mud. However, the DIF still contains some solids to form mud cake to prevent fluid loss. 
     Prior to completing the reservoir section of the wellbore with the ICD screen completions, the DIF is either replaced by or conditioned to a low or zero solids system. If, however, the DIF in the wellbore is not replaced by or conditioned to a low or zero solids system, and the ICD screen completions are lowered into an unconditioned section of mud which contains solids, the ICD screen completions may plug and, as a result, well performance and productivity may be poor or significantly decline. Even if the ICD screen completions are introduced into a conditioned well, screen plugging can occur as a result of mud cake and invaded mud solids flow back. 
     It is therefore an aim of the present invention to provide a flow control apparatus and method of cleaning the flow control apparatus, which addresses at least some of the afore-mentioned problems. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a method of cleaning a flow control apparatus in a wellbore comprising: providing in a wellbore a flow control apparatus comprising at least one screen and at least one inflow control device wherein a fluid inflow path is provided through the at least one screen and from an outer portion to an inner portion of the at least one inflow control device; targeting the at least one inflow control device with a treatment fluid; and delivering the treatment fluid such that the fluid flows in a reverse direction along the fluid inflow path. 
     Thus, the treatment fluid may pass through the inflow control device and then through or over the screen and dislodge, dissolve or disperse material on or in the screen. The treatment fluid may be circulated back through another portion of the flow control apparatus, or may flow along an annulus between the apparatus and a surrounding well bore. 
     The step of targeting the at least one inflow control device may comprise inserting a treatment tool into the wellbore for the delivery of the treatment fluid. 
     The method may further comprise the step of locating the treatment tool on a locator provided by the flow control apparatus. 
     According to a second aspect of the present invention there is provided a flow control apparatus for use in a wellbore, the flow control apparatus comprising: a screen; a first inflow control device and a second inflow control device; wherein a fluid inflow path is provided through the screen and from an outer portion to an inner portion of each inflow control device. 
     A further aspect of the invention comprises circulating treatment fluid from an inner portion to an outer portion of the first inflow control device, along the screen, and then through an outer portion to an inner portion of the second inflow control device. 
     Embodiments of the second aspect of the invention provide an improved flow control apparatus which facilitates effective cleanup operations since treatment fluid can be directed along the length of the screen from the first inflow control device (ICD) to the second inflow control device. Accordingly, the treatment fluid will tend to be flowed over or through most or all parts of the screen. Furthermore, embodiments of the present invention may be significantly more efficient at removing near wellbore damage and screen plugging than previous apparatus since treatment fluids can more effectively reach areas of the completion in the targeted vicinity of the ICDs. It is noted that, to date, cleaning of a completion had been attempted by simply pressurising a length of the completion. However, as ICDs are designed to choke or restrict flow, this technique does not effectively result in the cleaning of screens provided in the wellbore. 
     A further advantage of the present invention is that the second ICD can serve as a back-up to the first ICD, should the first ICD become ineffective or inoperable during use. 
     The first inflow control device may be provided at one end of the screen and the second inflow control device may be provided at the opposite end of the screen. The orientation of the first and second screens may be such that they both face inwardly towards the screen. 
     The apparatus may comprise one or more further inflow control devices. Screens may be provided between each inflow control device. 
     The apparatus may further comprise an ICD locator configured for the alignment of a treatment tool to deliver targeted treatment fluid through at least one of the first or second inflow control devices. As such, improved placement of the treatment fluid for use in the flow control apparatus can be achieved. It will be understood that in certain embodiments, a treatment tool can be accurately positioned to straddle the flow control apparatus so that treatment fluid can be forced through an adjacent first ICD before flowing back through the second ICD. In a particular embodiment, the ICD furthest from the surface may be targeted with the treatment tool so that the treatment fluid can flow back through the nearest ICD and up to the surface. 
     The ICD locator may be constituted by a recess or an inwardly projecting ledge, shoulder or other projection on which the treatment tool can be located. The ICD locator may be retractable or collapsible (for example, by pressure activation or deactivation) so as to allow the treatment tool to pass by. In certain embodiments, the ICD locator may comprise a welding ring, a spring-loaded (e.g. dog) clip, or an inflatable straddle. 
     Each of the first and second inflow control devices may be provided for reservoir management. For example, the first and/or second ICDs may be configured to limit the inflow of oil, gas or water into the production tubing from the surrounding wellbore formations. Accordingly, the first and/or second ICDs may be of the type described in GB2448069 having an inner member and an outer member with a flow path therebetween and an elastomer member disposed within the outer member and adjacent the flow path, the elastomer member being capable of swelling on contact with an actuating agent to thereby restrict the inflow of oil, gas or water. 
     The screen may comprise a tube of mesh configured to restrict the flow of solids, such as sand particles, therethough. 
     The screen may be provided around a base pipe, in a spaced relationship therefrom. 
     The fluid inflow path may comprise the space between the base pipe and the screen. 
     The flow control apparatus may further comprise at least one packer or seal configurable to seal the annulus between the apparatus and the surrounding wellbore. The at least one packer or seal may be extendable or expandable to selectively seal the gap between the apparatus and the surrounding wellbore. 
     In a specific embodiment, a first packer is configured to seal the annulus between the apparatus and the surrounding wellbore in a region above the first ICD and a second packer is configured to seal the annulus between the apparatus and the surrounding wellbore in a region below the second ICD. 
     According to a third aspect of the present invention there is provided a treatment tool for use with the flow control apparatus according to the second aspect of the invention, the treatment tool comprising: an inlet for treatment fluid to flow into the tool; at least one outlet for treatment fluid to flow out of the tool; and a treatment locator configured for the alignment of the at least one outlet with the first inflow control device of the flow control apparatus. 
     The treatment locator may comprise a recess or an outwardly projecting flange, shoulder or other projection. The treatment locator may be retractable or collapsible (for example, by pressure activation or deactivation) so as to allow the treatment tool to pass the first inflow control device. In certain embodiments, the treatment locator may comprise a welding ring, a spring-loaded (e.g. dog) clip, or an inflatable straddle. 
     According to a fourth aspect of the present invention there is provided a system for cleaning a flow control apparatus in a wellbore comprising: the flow control apparatus according to the second aspect of the present invention and the treatment tool according to the third aspect of the present invention. 
     It will be understood that in embodiments of the first aspect of the invention, the treatment tool employed may be in accordance with the third aspect of the present invention and the optional features described above in relation to both the second and third aspects of the invention may, optionally, be included in the apparatus employed in the method of the first aspect of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments of the invention will now be described with reference to the accompanying drawings, in which: 
         FIG. 1  shows a side view of a known flow control apparatus with the upper half of the device shown in cross-section; 
         FIG. 2  shows a side view of a flow control apparatus according to an embodiment of the present invention, with the upper half of the device shown in cross-section; 
         FIG. 3  shows a view similar to that shown in  FIG. 2  but with a treatment tool in place; 
         FIG. 4  shows an enlarged perspective view of the apparatus shown in  FIG. 3 ; 
         FIG. 5A  shows a view similar to that shown in  FIG. 2 , wherein the screen is plugged with mud prior to treatment; 
         FIG. 5B  shows a view similar to that shown in  FIG. 3 , during treatment of the screen; 
         FIG. 5C  shows a view similar to that shown in  FIG. 5A , after the screen has been treated; 
         FIGS. 6A to 6D  show a flow control apparatus according to a further embodiment of the present invention, that is similar to that shown in  FIGS. 2 through 5C , but showing the inflow control devices (ICDs) in greater detail; 
       More specifically,  FIG. 6A  shows a side view of the flow control apparatus; 
         FIG. 6B  shows a view similar to that of  FIG. 6A  but with the upper half of the apparatus shown in cross-section; 
         FIG. 6C  shows an enlarged cross-sectional view of the first ICD of  FIGS. 6A and 6B ; and 
         FIG. 6D  shows an enlarged cross-sectional view of the second ICD of  FIGS. 6A and 6B . 
     
    
    
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS 
     With reference to  FIG. 1 , there is illustrated a known flow control apparatus  10  comprising a tubular metal base pipe  12  having a first end  14  and a second end  16 . A male coupling  17  is provided at the first end and a female coupling  18  is provided at the second end  16  for attachment to further pieces of completion equipment (not shown). Towards the first end  14  there is provided a single inflow control device (ICD)  20  which comprises an inner member  22  constituted by the base pipe  12  and having a series of apertures  23  therein, and an outer member  24  surrounding the inner member  22  and defining part of an inflow path therebetween. A spacer  28  is disposed between the inner member  22  and the outer member  24  and is provided with a series of nozzles  30  therethrough. 
     Disposed around the base pipe  12  at one end of the ICD  20  is a tubular wire wrap screen  32 . The screen  32  surrounds and is spaced from the base pipe  12 . In use, a production fluid inflow path  26  extends through the screen  32  into the region between the base pipe  12  and the screen  32 . The inflow path then passes through the nozzles  30 , between the members  22 ,  24  and through the apertures  23 . Although fluid can flow through the screen  32 , sand and other particulates are prevented from passing therethrough and they are therefore prevented from entering the base pipe  12  through the ICD  20 . 
     An end ring  34  is provided at the other end of the screen  32  to secure the screen to the base pipe  12 . 
     In accordance with the first aspect of the invention, the flow control apparatus  10  may be cleaned by targeting and delivering a treatment fluid through the ICD  20  such that it flows in the reverse direction along the inflow path  26 , and thus flows along and through the screen  32 . The treatment fluid thus dislodges, dissolves or disperses material which may have become adhered to or gathered in or on the screen. 
     The treatment fluid and any dislodged or dispersed material may be circulated out of the bore, for example passing along the annulus between the apparatus and the surrounding bore wall, passing back through a further ICD, or through some other port or valve. 
       FIG. 2  illustrates a flow control apparatus  40  according to an embodiment of the second aspect of the present invention. As above, the flow control apparatus  40  comprises a tubular metal base pipe  42  having a first end  44  and a second end  46 . Couplings  47 ,  48  are provided at the base pipe ends  44 ,  46  for attachment to adjacent elements of the completion. Towards the first end  44  there is provided a first inflow control device (ICD)  50  which comprises an inner member  52  constituted by the base pipe  42  and having a series of apertures  53  therein, and an outer member  54  surrounding the inner member  52  and defining an inflow path  56  therebetween. A spacer  58  is disposed between the inner member  52  and the outer member  54  and is provided with a series of nozzles  60  therethrough. 
     Also as described above in relation to  FIG. 1 , a tubular wire wrap screen  62  is disposed around and spaced from the base pipe  42 , adjacent one end of the ICD  50 . However, in accordance with an embodiment of the second aspect of the present invention, a second ICD  70  is provided at the other end of the screen  62 . The second ICD  70  is identical to the first ICD  50  but is orientated in an opposite direction when compared to the first ICD  50  so as to provide a mirror image thereof when viewed from the side as per  FIG. 2 . Accordingly, the second ICD  70  comprises an inner member  72  constituted by the base pipe  42  and having a series of apertures  73  therein, and an outer member  74  surrounding the inner member  72  and defining an inflow path  76  therebetween. A spacer  78  is disposed between the inner member  72  and the outer member  74  and is provided with a series of nozzles  80  therethrough. 
     While a wellbore is producing, production fluid will flow through the screen  62 , along the annulus between the screen  62  and the base pipe  42 , through the nozzles  60 ,  80 , between the inner and outer members  52 ,  72 , and  54 ,  74 , and through the apertures  53 ,  73  and into the base pipe  42 . The production fluid will then flow to surface, co-mingling with production fluid which has passed through other ICDs at other locations on the completion. 
     An ICD locator in the form of a collapsible inwardly projecting annular ledge  82  is provided on the inner surface of the base pipe  42  between the first end  44  and the first ICD  50 . 
       FIGS. 3 and 4  illustrate the flow control apparatus  40  of  FIG. 2  with a treatment tool  90  according to an embodiment of the third aspect of the present invention, located for a cleaning operation which will typically be carried out after a completion incorporating the apparatus  40  has been run into and set in the wellbore. The treatment tool  90  comprises a cylindrical support  92  having a series of five radial jetting nozzles  94  arranged to allow fluid to flow from an interior of the support  92  to an exterior of the support  92 . The treatment tool  90  also comprises a treatment locator (or stop shoulder) in the form of an annular outwardly radially projecting flange  96  configured to abut the corresponding ledge  82  of the flow control apparatus  40  to thereby align the jetting nozzles  94  with the first ICD  50 . 
     First and second expandable annular sealing elements  98  are provided between the treatment tool  90  and the flow control apparatus  40 , to ensure fluid flow from the series of jetting nozzles  94  is directed through the apertures  53  and into the first ICD  50 . It will be understood that in order to arrive at the position shown in  FIG. 3 , the ICD locator  82  must either be collapsed to allow the treatment tool  90  and expanded sealing elements  98  to pass by or the sealing elements  98  themselves must be collapsed and only expanded when the treatment tool  90  is in position. 
       FIG. 5A  shows a view similar to that shown in  FIG. 2 , wherein the screen  62  of the flow control apparatus  40  is plugged with mud prior to a cleaning treatment.  FIG. 5B  shows a view similar to that shown in  FIGS. 3 and 4 , with the treatment tool  90  located within the flow control apparatus  40  (by engagement of the flange  96  with the ledge  82 ) and with fluid treatment being dispensed from the treatment tool  90  to clean the screen  62 . Accordingly, it can be seen that treatment fluid  100 , which in this case is a mixture of water with surfactants, anticoagulants and the like, is introduced via the treatment tool  90  and is dispensed through the jetting nozzles  94  into a chamber defined by the sealing elements  98  and then into the first ICD  50  through apertures  53 . The treatment fluid  100  then flows through the nozzles  60  to the exterior of the ICD  50  before flowing along the length of the screen  62  to dislodge, dissolve or disperse the mud and other solids plugging the screen  62  and disperse these materials in the treatment fluid before it enters the second ICD  70  through the nozzles  80  and returns to the interior of the flow control apparatus  40  via the apertures  73 . Accordingly the treatment fluid  100  is encouraged to flow along a treatment fluid flow path  102  from the interior to the exterior of the first ICD  50 , along the length of the screen  62 , and from the exterior to the interior of the second ICD  70 . As such, the present invention provides an improved apparatus for the efficient cleaning of an ICD screen completion. 
       FIG. 5C  shows a view similar to that shown in  FIG. 5A , after the fluid treatment has been completed and the treatment tool  90  has been removed. Thus, it can be seen that the screen  62  is no longer plugged with mud and the cleaning operation has been successful. 
       FIGS. 6A to 6D  show a flow control apparatus  100  according to another embodiment of the present invention. The flow control apparatus  100  is similar to that shown in  FIGS. 2 through 5C  and so like reference numerals will be used where appropriate. Thus, the flow control apparatus  100  comprises a tubular metal base pipe  42  having a first inflow control device (ICD)  102  and a second inflow control device (ICD)  104  provided at opposite ends of a tubular wire wrap screen  62  disposed around the base pipe  42 . Although only the ends of the screen  62  are specifically depicted in  FIGS. 6A and 6D , it will be noted that the screen  62  is continuous between the first and second ICDs  102 ,  104 . 
     As best shown in  FIGS. 6C and 6D , the first and second ICD&#39;s  102 ,  104  are identical but are orientated so that they each face inwardly towards the screen  62 . Each ICD  102 ,  104  comprises a inner member  52  constituted by the base pipe  42  and having a series of apertures  53  therein, and an outer member  54  surrounding the inner member  52  and defining an inflow path  56  therebetween. A spacer  58  is disposed between the inner member  52  and the outer member  54  and is provided with a series of nozzles  60  therethrough. The nozzles  60  continue the inflow path  56  from an annulus  106  between the screen  62  and the base pipe  42 , through the ICDs  102 ,  104  and into the base pipe  42  via the apertures  53 . At the ends of each ICD  102 ,  104  opposite to the screen  62  there is provided a sealing mechanism  108  to seal the gap between the outer member  54  and the inner member  52  so that fluid is only permitted to flow through each ICD  102 ,  106  and into base pipe  42  from the annulus  106 . 
     As above, when a wellbore is producing, the production fluid will flow through the screen  62 , along the annulus  106  between the screen  62  and the base pipe  42 , through the nozzles  60  between the inner and outer members  52 ,  54  and through the apertures  53  into the base pipe  42 . The production fluid will then flow to surface, co-mingling with production fluid which has passed through other ICDs at other locations on the completion. 
     Should the screen  62  ever become plugged with mud or other particulates, either prior to commencement of production or at a later point in the life of the well, it is possible to clean the flow control apparatus  100  by targeting one of the ICDs  102 ,  104  and delivering treatment fluid through the apertures  53  so that the treatment fluid is forced in reverse direction along the flow path  56  and along the annulus  106  to the other ICD  102 ,  104  before re-entering the base pipe  42  and flowing to the surface. Gradually pressure will build up along the annulus  106  and this will help to force the mud or other particulates outwardly from the screen  62  to thereby unblock the screen  62 . 
     It will be appreciated by persons skilled in the art that various modifications may be made to the above embodiments without departing from the scope of the present invention. For example, embodiments of the invention may be utilised to deliver stimulation fluid to a wellbore section adjacent the apparatus. The fluid may be targeted to a specific well bore section.