Patent Publication Number: US-8118104-B2

Title: Downhole valve with pass through ID

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application, pursuant to 35 U.S.C. §119, claims priority to U.S. Provisional Application Ser. No. 61/021,731 filed Jan. 17, 2008. That application is incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     Embodiments disclosed herein relate generally to downhole drilling components. More particularly, embodiments disclosed relate to apparatus and methods to control fluid communication to bottom hole assemblies. 
     2. Background Art 
     In the drilling, completing, or reworking of oil wells, a variety of downhole tools may be used.  FIG. 1  shows one example of a conventional drilling system for drilling an earth formation. The drilling system includes a drilling rig  10  used to turn a drilling tool assembly  12  which extends downward into a wellbore  14 . Drilling tool assembly  12  includes a drillstring  16 , a bottom hole assembly (“BRHA”)  18 , and a drill bit  20 , attached to the distal end of drillstring  16 . 
     Drill string  16  may comprise several joints of drill pipe  16   a  connected end to end through tool joints  16   b . Drillstring  16  may be connected, or “made-up”, where drill pipe  16   a  is tightened to a certain amount. Drillstring  16  maybe disconnected, or “broken-out”, where drill pipe  16   a  is loosened and taken apart. Drill string  16  transmits drilling fluid (through its central bore) and rotational torque from drill rig  10  to BHA  18 . Drill pipe  16   a  provides a hydraulic passage through which drilling fluid is pumped. The drilling fluid discharges through selected-size orifices in the bit (e.g., “jets”) for the purposes of cooling the drill bit and lifting rock cuttings out of wellbore  14  as it is drilled. 
     Bottom hole assembly  18  includes a drill bit  20  and may also include additional components attached between drill string  16  and drill bit  20 . Examples of additional BHA components include drill collars, stabilizers, measurement-while-drilling (“MWD”) tools, logging-while-drilling (“LWD”) tools, and downhole motors. 
     In some instances, well-intervention operations may be conducted using single-strand or multi-strand wireline or cable for intervention in oil or gas wells. Logging while drilling (LWD) is the measurement of formation properties during the excavation of the hole, or shortly thereafter, through the use of tools integrated into the bottom hole assembly. LWD, while sometimes risky and expensive, has the advantage of measuring properties of a formation before drilling fluids invade deeply. Further, many wellbores prove to be difficult or even impossible to measure with conventional wireline tools, especially highly deviated wells. In these situations, LWD measurement ensures that some measurement of the subsurface is captured in the event that wireline operations are not possible. 
     During downhole operations, for example, drilling, workover, and/or completion, one or more fluids may be present in both the bore of the drillstring and an annulus region formed between the drillstring and casing in the wellbore. When making up or breaking out connections in a wellbore having fluids present in the bore and the annulus region, unwanted fluid flow may occur in that the fluid from the annulus may rush into and up the bore of the drillstring. Such an occurrence is called a “U-tubing” effect and is well known in the industry. The U-tubing effect may be caused by a disturbance in the fluid equilibrium of the wellbore. For example, the fluids in the different volumes (i.e., the bore and the annulus region) may attempt to “level out,” thereby creating equilibrium in the wellbore. Making up and/or breaking out drillstring connections interrupts the equilibrium and causes the unwanted flow of fluid into the bore. 
     Accordingly, there exists a need for a device to control fluid flow through a drillstring bore during downhole operations such as when making up or breaking out connections. Also, a device through which wireline tools and cables may be run downhole with minimal restriction would be well received in industry. 
     SUMMARY OF THE DISCLOSURE 
     In one aspect, embodiments disclosed herein relate to a downhole valve assembly attached to a drillstring, the valve assembly including an upper drillstring connection, a lower drillstring connection, and a tubular body comprising a through bore, and further including a weight activated mechanism configured to close the through bore when the drillstring is lifted. 
     In other aspects, embodiments disclosed herein relate to a method to control fluid flow through a drillstring, the method including providing a downhole valve assembly proximate a bottom hole assembly, wherein the valve has a full bore clearance when in an open position, and further including closing the downhole valve assembly by lifting the drill string. 
     In other aspects, embodiments disclosed herein relate to a downhole valve assembly attached to a drillstring, the valve assembly including an upper drillstring connection, a lower drillstring connection, and a tubular body comprising a through bore, and a weight activated mechanism configured to close the through bore when the drillstring is lifted. The weight activated mechanism includes a fin valve disposed on a lower end of a valve body, the fin valve including a plurality of fin elements configured to provide a seal in the bore in a closed position. 
     Other aspects and advantages of the disclosure will be apparent from the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a drilling system to drill earth formations in accordance with the prior art. 
         FIG. 2A  is a section view of a downhole valve assembly in an open position in accordance with embodiments of the present disclosure. 
         FIG. 2B  is a section view of a fin valve in accordance with embodiments of the present disclosure. 
         FIG. 3  is a section view of a downhole valve assembly in a mid-stroke position in accordance with embodiments of the present disclosure. 
         FIG. 4  is a section view of a downhole valve assembly in a closed position in accordance with embodiments, of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In one aspect, embodiments disclosed herein relate to downhole drilling components. More particularly, embodiments disclosed herein relate to apparatus and methods for controlling fluid communication to a bottom hole assembly. Still further, embodiments disclosed herein relate to a downhole valve assembly for controlling fluid flow through a bore to bottom hole assemblies. A weight activated downhole valve assembly of embodiments disclosed herein may be configured to control fluid flow through a drillstring bore during downhole operations such as when making up or breaking out connections, as well as allow wireline tools and cables to be run downhole through the bore with minimal restriction. 
     Referring to  FIG. 2A , a section view of a downhole valve assembly  100  is shown in accordance with embodiments of the present disclosure. Downhole valve assembly  100  includes an outer tubular body  130  which has a lower cap or sub  115  threadably engaged on its lower end. Further, a valve body  105  having a bore  102  therethrough and threadably engaged with an upper cap  110 , and a spring  120  disposed between valve body  105  and upper cap  110  are enclosed within outer tubular body  130 . Further, a fin valve  125  is attached to a lower end of valve body  105  and in bore  102 . Upper cap  110  is configured to threadably attach to a drillstring (not shown), and lower sub  115  is configured to threadably engage a rotary tool. 
     Referring to  FIG. 2B , a section view of fin valve  125  is shown in accordance with embodiments of the present disclosure. Fin valve  125  is attached to a lower end of valve body  105  through methods known to those skilled in the art. Fin valve  125  includes a plurality of fin elements  126  configured as individual “fingers” or “closing elements” which are configured to expand and allow fluid flow through bore  102 , or compress and restrict fluid flow through bore  102  by forming a seal within. Further, fin elements  126  may seal on a wireline or other generally circular cross-sectioned object run through the bore of valve body  105 . 
     In certain embodiments, fin valve  125  may include between three and six individual fin elements  126  configured to either expand or compress and mesh with each other. Fin elements  126  may be arranged in a circular configuration about a central axis  128  and attached to valve body  105  at “hinge” points  127 . In this way, fin elements  126  may rotate or pivot about hinge point  127  in directions  129 A,  129 B when expanding or compressing. 
     In certain embodiments, fin elements  126  may have a triangular shape similar to that shown in the figures. However, one of ordinary skill in the art will appreciate that fin elements  126  may be configured in any useful shape, such as trapezoidal or rounded triangular, such that adequate sealing may be provided through bore  102 . Further, fin elements  126  may be any polymer material known in the art. Various types of polymers may be selected and used depending upon downhole temperatures, drilling fluid types, or other downhole conditions known to those skilled in the art. In certain embodiments, fin elements  126  may be a polymer/steel combination. For example, fin elements  126  may be co-formed with a polymer material for sealing and a rigid steel backing for support. 
     Referring back to  FIG. 2 , downhole valve assembly  100  includes spring  120  positioned above valve body  105 . The spring  120  may be a coiled spring, Belleville washer spring, or any other biasing mechanism known to those skilled in the art. Further, spring  120  may be formed of high cycle spring steel and other materials known to those skilled in the art. 
     Typically, downhole valve assembly  100  operates between an “open” position, in which fluid flow through bore  102  is allowed, and a “closed” position, in which fluid flow through the bore, is partially or filly restricted. Opening the valve and allowing fluid flow through the bore is accomplished by pushing down on downhole valve assembly  100 , thereby applying weight on the bit (“WOB”) or bottom hole assembly. In contrast, closing the bore is accomplished by lifting up on downhole valve assembly  100 , thereby decreasing weight on the bit. Operation of downhole valve assembly  100  is described in more detail in three different positions: the open position, the closed position, and a “mid-stroke” position. 
       FIG. 2A  shows downhole valve assembly  100  in the open or “free flowing” position which allows fluid flow  102  through the bore of downhole valve assembly  100  while drilling. In the open position, downhole valve assembly  100  may provide a full bore clearance allowing wireline cable or tools to be run downhole with minimal restriction. To configure downhole valve assembly  100  in the open position, weight is applied on the drillstring (not shown) which pushes downhole valve assembly  100  downward. Spring  120  is compressed against valve body  105  which forces fin valve  125  downward, allowing fin elements  126  ( FIG. 2B ) to expand radially outward into an upset region  117  in an inside diameter of lower sub  115 . Fluid flow  102  or wireline cable and tools running through the bore push radially outward on fin elements  126  ( FIG. 2B ) of fin valve  125 , keeping them in upset region  117 . In certain embodiments, other biasing mechanisms may be used to maintain fin elements  126  in upset region  117 , such as spring wire or other devices known to those skilled in the art. 
     Referring now to  FIG. 3 , a section view of downhole valve assembly  100  in a partially closed, or mid-stroke, position is shown in accordance with embodiments of the present disclosure. When drilling stops and WOB is reduced (i.e., pulling upward on drillstring  101 ), spring  120  is compressed as valve body  105  is pulled upwards. As valve body  105  moves upward, fin valve  125  is pulled upward through a tapered opening  132  in tubular body  130 . Tapered opening  132  provides that increasing forces may be applied to fin elements  126  ( FIG. 2B ) as they travel upward into bore  102  and diameter of tapered opening decreases. The configuration of tapered opening  132  provides a “wedging” action which compresses fin elements  126  ( FIG. 2B ) of fin valve  125  in bore  102 . The wedging action provides the primary sealing force once the fin elements have fully compressed in the bore of downhole valve assembly  100 . As shown in  FIG. 3 , valve body  105  is in the mid-stroke position, which in certain embodiments may be approximately 2.5 inches upward from the open position. In the mid stroke position, bore  102  may have a significant reduction of area, which will restrict fluid communication to the rotary tool (not shown). 
     Referring now to  FIG. 4 , a section view of downhole valve assembly  100  in a fully “closed” position is shown in accordance with embodiments of the present disclosure. In the closed position, spring  120  may be in full compression, or close to full compression, and bottomed against upper cap  110 . Fin elements  126  ( FIG. 2B ) of fin valve  125  may be compressed, completely closing the ID of downhole valve assembly  100  and preventing fluid communication  102  to the BHA (not shown). Further, in alternate embodiments such as high temperature applications, fin elements  126  ( FIG. 2B ) of fin valve  125  may be configured to form a metal-to-metal seal in the bore which will be understood by those skilled in the art. In this instance, sealing forces provided by the wedging action of tapered  132  opening as described previously may be greater to form a sufficient metal-to-metal seal. 
     Further, in this position, when the stroke of downhole valve assembly  100  reaches a maximum, about five inches in certain embodiments, internal components may make shoulder to shoulder contact and allow tensile lifting loads to be transmitted through the outer tubular portion of valve body  105 . For example, an upper end of spring  120  contacts a mating shoulder  111  of upper cap  110  and a lower end of spring  120  contacts a mating shoulder  108  of valve body  120 , as shown in  FIG. 4 . In certain embodiments, in the event of a failure downhole, downhole valve assembly  100  may be configured to “fail” in the open position. The ‘fail open’ feature may be used in the event of a bottom hole assembly (“BHA”) failure, when it may be necessary to pass certain tools through the bore with minimum restriction. This feature provides that downhole valve assembly  100  may never become stuck in the closed position, which may result in a loss of tools downhole. 
     In certain embodiments, downhole valve assembly  100  in a fully closed position may completely seal the bore, preventing any fluid communication to the BHA. In alternate embodiments, downhole valve assembly  100  in a fully closed position may partially seal the bore, reducing fluid communication to the BHA, but not completely shut if off. In still further embodiments, a wireline or other small diameter tubular may be run through the bore when downhole valve assembly  100  is closed, thereby closing the fin valve and sealing about the wireline. Small diameter tubular may include slick line tubing and wireline tools known to those skilled in the art. Further, the seal created in the bore by the fin valve may seal against fluid flow from the annulus attempting to flow up the bore, also called the U-tubing effect. 
     In certain embodiments, the downhole valve assembly may include a spline connection between an outer surface of the valve body and an inner surface of the mandrel. The spline connection may prevent rotation between the two components during the upward and downward movements of the downhole valve assembly, therefore limiting the movement between the two to vertical movement only. In further embodiments, the downhole valve assembly may be configured to allow rotational movement and vertical movement between the valve body and the mandrel which would be known to those skilled in the art. 
     In certain embodiments, downhole valve assembly may include a position indicator which transmits a signal to a drilling operator to indicate the current position of the fin valve. Pressure sensors, visual indicators, or other devices known to those skilled in the art may be used to indicate the position of the fin valve. The drilling operator may have a gauge, various light indicators, or other signaling components known to those skilled in the art to indicate the different positions of fin valve of the downhole valve assembly. 
     Advantageously, embodiments of the present disclosure provide a downhole valve assembly for controlling fluid communication to a BHA. The downhole valve assembly may simplify the downhole tool by replacing hydraulic systems used to seal the bore. The downhole valve assembly may reduce maintenance and improve reliability of the downhole valve assembly. Further, a rubber “fin cone” design of a fin valve may allow drilling operators to maintain a fully open ID while drilling, but a fully closed ID when making up and/or breaking out connections to reduce or prevent the U-tubing effect. Also, using the downhole valve assembly may allow wireline tools to be run through the fall ID of the drillstring with minimal restriction. 
     Still further, embodiments of the present disclosure may provide a shorter stroke that sealing elements must travel before sealing the ID of the drillstring, providing improved response time to seal the ID of the drillstring. Embodiments of the present disclosure further provide a fail open valve, where in the event of a BHA failure, the downhole valve assembly is automatically restored to an open position. This allows tools needed to access the BHA to pass through the ID with minimum restriction. Further, the ability to always access the BHA may decrease chances of losing tools downhole which may result in a loss of the well. 
     While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.