Abstract:
A valve for downhole use allows flow of mud or completion fluids but closes when subjected to produced hydrocarbons. The flow through the valve is through an annular passage that features a sleeve preferably made of rubber. The passage remains open during completion operations, but when hydrocarbons are produced the rubber swells and the passage is closed off. Applications include completions involving long horizontal runs and small inside diameter laterals where access to a sliding sleeve with coiled tubing or a wireline run tool is not practical.

Description:
FIELD OF THE INVENTION 
     The field of the invention is downhole valves and more particularly valves that can be operated between an open and closed position using the well fluid that flows through them. 
     BACKGROUND OF THE INVENTION 
     Downhole valves have been used to provide selective access from different strata into a well. Typically these valves employ a sliding sleeve to selectively align or mis-align openings on an inner sliding sleeve mounted concentrically with a housing. The sliding sleeve can have grooves or recesses near its end for engagement by a tool to slide the sleeve in one direction or another. Typically the tool to operate the sliding sleeve is delivered on coiled tubing or wireline, however, rigid tubing could also be used. 
     Many applications in deviated wellbores, particularly those with long horizontal sections, present unique difficulties to the traditional methods of operating sliding sleeve valves with tools delivered on coiled tubing or wireline. Other applications, such as junctions in multi-lateral systems have such small inside diameters so as to make operation of the sleeve using coiled tubing or wireline, virtually impossible. 
     One solution to this problem of lack of access for traditional tools to shift the sleeve has been to provide a local source of power, such as a battery, and use it to power the sleeve between the open and closed positions. However, there are still reliability issues with using battery power and should the valve fail to close, there is no backup way to get access to it to get it to close. 
     The need to use valves in applications where traditional type of access is not available, has spurred the need for the present invention. In seeking a more reliable way to operate a valve that, in effect, cannot be mechanically accessed, the valve of the present invention has been developed. The valve features, in a preferred embodiment, an annular passage lined with a material that is sensitive to some fluids but not to others. It can remain open until contacted by a fluid that makes the liner swell. The swelling closes off the flow path through the valve body to allow subsequent operations to take place. This valve type has particular application to screened main bores used in conjunction with open laterals. In such applications, high mud flow rates are experienced during completion operations making it desirable to bypass screens in the main bore completion. However, when production of hydrocarbons begins, it is desirable to close the bypass for the screens and direct production of hydrocarbons through such screens. The valve of the present invention can do this. Exposure to produced hydrocarbons can result in sufficient swelling to make the valve close. When this happens, the produced fluid can be directed to flow through a screen on the way to the surface. These and other advantages of the present invention will become apparent to those skilled in the art from a review of the description of the preferred embodiment and the drawings and the claims that appear below. 
     SUMMARY OF THE INVENTION 
     A valve for downhole use allows flow of mud or completion fluids but closes when subjected to produced hydrocarbons. The flow through the valve is through an annular passage that features a sleeve preferably made of rubber. The passage remains open during completion operations, but when hydrocarbons are produced the rubber swells and the passage is closed off. Applications include completions involving long horizontal runs and small inside diameter laterals where access to a sliding sleeve with coiled tubing or a wireline run tool is not practical. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of a wellbore showing the main bores completed with screens and the valve of the present invention positioned in the screen assemblies adjacent laterals with no production pipe; 
         FIG. 2  is a detailed view from  FIG. 1 , showing the valve of the present invention in the open position; 
         FIG. 3  is the view of  FIG. 2  with the valve in the closed position; 
         FIG. 4  is a section view through the valve, shown in the open position; 
         FIG. 5  is a section through line  5 - 5  of  FIG. 4 ; and 
         FIG. 6  is a section view through line  6 - 6  of  FIG. 4  with the valve in the closed position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates an application of the present invention. Well  10  has production tubing  12  going to a lateral  14 . At lateral  14  the well  10  splits into branches  16  and  18 , which are respectively cased with casing  20  and  22 . The production tubing  24  and  26  extends respectively through casing  20  and  22  to respectively terminate in screen assemblies  28  and  30 . Branch  16  has several branches  32  and  34  which are left “barefoot”, that is to say there is no production tubing in them and this is their condition during completion and in subsequent production. Similarly branch  18  has several branches such as  36  and  38  that are likewise barefoot. Screen assembly  28  has a valve  40  that allows high flow rates down annulus  42 , represented by arrow  44  shown in  FIG. 2 . These high flow rates of drilling mud or other completion fluids can bypass screen assembly  28  from branch  32  by flowing through screen assembly  28  after passing through open valve  40 . This return flow is represented by arrow  46 . The same flow pattern exists from branches  36  and  38  into branch  18  and branch  32  into branch  16 . The may be an offset between the start of a branch and the valve through which completion fluids or mud will flow. If that is the case the flow will go through the annular space around the screen assembly, such as  28  or  30  until reaching a valve such as  40  or  48 . 
     As shown in  FIG. 3 , when the valve  40  moves to a closed position because branch  32  is in production, the flow uphole  50  goes into annulus  42  and through the screen assembly  28 . Essentially the production flow is forced through the screen assemblies  28  and  30  with the valves  40  and  48  closed due to production from the branches below them. This is to be contrasted with the flow pattern bypassing the screen assemblies  28  and  30  when valves  40  and  48  are open during completion with mud or other fluids. 
       FIGS. 4-6  show the operation of one embodiment of the valve  40  or  48 . The valve such as  40  has a circular inlet  52  made of a plurality of smaller openings  54 . Valve  40  has a mandrel  56  with a central passage  58 . An annular path  60  begins near openings  54  and terminates at end wall  62 . A series of openings  64  allow access from annular path  60  into central passage  58 . Connection  66  is secured to the screen assembly  28  to allow returning mud or other completion fluid to pass through the interior of the screen assembly, such as  28 . A sleeve  68  is disposed in annular passage  60  and when drilling mud or completion fluids are flowing has a small enough thickness to allow high flow rates through annular passage  60  and up through the screen assembly  28  to the surface. However, if a branch feeding flow to valve  40  is allowed to come in and produce hydrocarbons, the sleeve  68  comes in contact with the hydrocarbons and proceeds to swell to such an extent so as to block annular passage  60  against further flow. The produced stream can no longer short circuit the screen assembly  28  by flowing through passage  58 . Rather, the produced flow proceeds outside of coupling  66  until it comes upon a screen section from screen assembly  28 . At that time, as desired, the produced fluids are forced through a screen to limit production of sand or other impurities.  FIG. 5  shows sleeve  68  before swelling and  FIG. 6  shows sleeve  68  after swelling toward the closed position. 
     While the preferred material for sleeve  68  is an elastomer, rubber, EPDM or Halobutyl which swells dramatically when exposed to hydrocarbons, the valve of the present invention encompasses other designs that will pass mud and completion fluids and can be triggered to close upon commencement of production flow. Thus the sleeve  68  can be made of other materials than rubber, such as elastomers, and does not need to be uniform along its length. It can comprise of combinations of materials that exhibit swelling or expand to close a flow path when exposed to hydrocarbons. Alternatively, the sleeve material can be sensitive to produced or injected water, such as a clay like bentonite. Alternatively, the material that will close the valve  40  can be sensitive to any downhole fluid but isolated from it during the completion process. Later, when it is desired to put the branches below valve  40  into production such that production from those branches will flow through the screen the layer  70  that is placed over the sleeve can be defeated, in a variety of ways to expose the produced fluids to the sleeve  68  so that it can swell and close the annular passage  60 . For example the sleeve  68  can be made from clays that expand with water such as bentonite or cements or fly ash or other materials that will swell and stay rigid enough to redirect flow. The protective cover  70  can be removed by being dissolved such as by chemical reaction or other form of attack. Alternatively, high flow rates or applied pressure differentials can erode or physically displace the protective covering  70 . Water can be from produced fluids or deliberately introduced from the surface. 
     Those skilled in the art can readily see that the various designs described above allow for a valve to operate reliably in situations where using coiled tubing or wireline is not practical. The design removes the uncertainties of relying on a downhole battery as the power source to operate the valve. Because of its simplicity and reliability of operation, it provides a useful tool when trying to bring in barefoot branches that require high flow rates for completion making it imperative to bypass a screen assembly while still having the flexibility to later direct produced flow from the barefoot branches through a screen assembly, due to the closure of such a valve. Other, more common applications of sliding sleeve valves downhole can also benefit from the valve of the present invention. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the invention.