Abstract:
A plug assembly and method for pressure testing a shaft having a generally cylindrical member with a deformable outer surface comprised of alternating soft and rigid ribs and a central void for reception of a sealing component having a sealable central bore, a tubular adapter capable of releasable attachment to a drill pipe and releasably engaged to the cylindrical member, a plurality of ports about the circumference of the member for upward flow of fluid through the member and a receptacle in the member for placement of the sealing component for fixed attachment inside the member for creating a seal for testing pressure. The sealing component may use a ball valve to regulate flow and the cylindrical member may have rigid sections implanted between soft sections during manufacture to facilitate sealing upon pressurization.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on provisional U.S. patent application No. 61/529,356 entitled “Plug and Pressure Testing Method” filed on Aug. 31, 2011, which is hereby incorporated by reference as if fully set forth herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a subsea testing method, and more particularly to a Plug and Pressure Testing Method and Apparatus for use with a Blow Out Preventer (BOP). 
       BACKGROUND OF THE INVENTION 
       [0003]    Numerous devices presently exist for testing pressure on down hole installations used in the extraction of oil and gas. In certain applications, plugs are first inserted into a shaft and after reaching a desired location, the line is pressurized and tested for leakage and pressure readings. It is also required that the shear rams on a BOP must be tested, which means that the drill pipe needs to be disconnected, pulled up above the shear rams and then later latched back into the plug for retrieval. In many instances the devices employed are not easily removed or require extensive downtime for their operation. Thus there exists a need to more easily install and remove a plug and testing apparatus from the hole to maintain and to restore functionality to an oil and gas well. 
       SUMMARY OF THE INVENTION 
       [0004]    In accordance with a preferred embodiment of the invention, there is shown plug assembly for pressure testing a shaft having a generally cylindrical member having a deformable outer surface and a central void for reception of a sealing component having a sealable central bore, the member having a lower end having a circumference; a tubular adapter capable of releasable attachment to a drill pipe and releasably engaged to the sealing component; a plurality of ports about the circumference of the member for selective flow of fluid through the member; and a receptacle in the member for placement of the sealing component for fixed attached inside the member for creating a seal in the shaft. 
         [0005]    In accordance with a preferred embodiment of the invention, there is shown a method for testing pressure on a blow out preventer having the steps of inserting into a shaft a generally cylindrical member having a deformable outer surface and a central void for reception of a sealing component having a sealable central bore, attaching an adapter to a drill pipe and engaging about said sealing component and inserting said sealing component into said member via pressure, pressurizing the shaft through the void to test the pressure in the shaft; removing the adapter from the member; and grinding the cylindrical member and said sealing component in situ and removing any debris from the shaft. 
         [0006]    In accordance with a preferred embodiment of the invention, there is shown an assembly for pressure testing a blow out preventer having a generally tubular member having a deformable outer surface and a notch on the inside diameter of the member, a cylindrical sealing component engaged to an adapter and a lower end for engaging the notch, an adapter capable of releasable attachment to a drill pipe and releasably engaged to the tubular member, a plurality of ports about the circumference of the member for flow of fluid about the member, a plurality of rigid wedges radially disposed about the circumference of the tubular member between deformable regions on the outer surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. 
           [0008]      FIG. 1 , shows cross sectional views of a test plug according to a preferred embodiment of the invention before full insertion into a shaft. 
           [0009]      FIG. 2  shows a perspective view of a test plug according to a preferred embodiment of the invention after full insertion into a shaft. 
           [0010]      FIG. 3  shows a cross sectional view of  FIG. 1  according to a preferred embodiment of the invention after insertion and removal of an adapter. 
           [0011]      FIG. 4  shows a cross sectional view along  4 - 4  of  FIG. 5  of a preferred embodiment of the invention. 
           [0012]      FIG. 5  shows a perspective cutaway and half portion of a preferred embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    Referring now to  FIG. 1 , a cross sectional view of test plug  10  is illustrated according to a preferred embodiment of the present application. Test plug  10  is a combination deformable outer shell or housing component  30  and internal sealing component  20  having adaptor  40  for creating a pressurizeable blockage. This also allows fluid to pass through test plug  10  to keep a constant bottom hole pressure and not compromise the well formation. Test plug  10  is attached to the drill pipe by means of adapter  40  for pressurization on the top of the plug. Ports around the periphery of the plug (more fully shown in  FIGS. 4 and 5 ) allow for flow around the plug when inserting. When testing, internal sealing component  20  is pushed into a notched receptacle to form a tight seal to pressure test. In a preferred embodiment, the periphery of the plug is comprised of lower durometer elastomer which expands upon insertion to create a tight seal. A plastic portion inside the softer outer shell has a check ball valve that moves upward if there is any upward pressure. When fully engaged, the ball valve closes and creates a seal. This permits pressure testing of the annulus. After testing, an adapter affixed to the plastic portion is right turned out and removed from the test pipe and the shear rams can be tested. Test pressure increases the seal contact pressure and also increases the bond strength of the grip. The drill bit then can grind the tool plug completely to permit removal of the plug pieces that have been cut up by the drill which will become part of the drilling returns. 
         [0014]    As is illustrated in  FIG. 1 , test plug  10  includes a housing component  30 , an internal sealing component  20 , and adapter  40 . Housing component  30  may be substantially made of a deformable elastomer and plastic combination as further described below. As test plug  10  is inserted into a well shaft, housing component  30  makes contact with the shaft&#39;s inside diameter and is generally cylindrical in shape with a central opening along its length as described below. Test plug  10  is lowered or raised to a desired depth typically below the blowout preventer and the  22 ″ casing hanger away from the casing adapter seal areas. When it becomes desirable to operate test plug  10 , a pipe connected to adapter  40 , which adapter  40  is frictionally engaged to internal sealing component  20 , is pressured downward to force internal sealing component  20  downward into housing component  30 . Internal sealing component  20  engages notch  23  within housing component  30 . As the plug is inserted, radial ports  65 , shown in  FIG. 4  about the periphery of the plug, permit flow upward to equalize pressure. 
         [0015]    A ball check valve  24  shown in  FIG. 2  is included to equalize the external pressure with that inside the drill pipe while running in the hole pressure below internal sealing component  20 . Adapter  40  is provided to establish an annular connection to the internal sealing component  20  for passage of fluid when necessary and insertion of the tool. 
         [0016]    Referring further to  FIG. 2 , test plug  10  is illustrated wherein internal sealing component  20  has been inserted into the preformed opening of housing component  30  and engaged at notch  23  in housing component  30 . A ball check valve  24  rests to keep sealed the opening of internal sealing component  20  so that fluid is not allowed to escape. Adapter  40  remains in the resting position above the opening of internal sealing component  20  As pressure is applied through adapter  40  which is in turn engaged to pipe (not shown), pressure testing is permitted since the downward flow has been blocked by the plug assembly. This activates the internal sealing component  20  which reacts on the lower section of the housing component  30 , gripping the internal walls of the pipe about radial fins  70  and setting seal lip  75  on the inside diameter (ID) as shown in  FIGS. 3 and 4 . The pressure can then be released from the drill pipe and the rams closed around them to allow pressure testing of the wellhead connector and other functions. The annular pressure acts down on internal sealing component  20  which increases the seal and grip on accordance with the increase of test pressure. Ball check valve  24  is now free to allow for any fluid that may bypass the seal to escape up the drill pipe so as not to over pressurize the well bore. 
         [0017]    Upon pressurization, internal sealing component  20  is forced into housing component  30 . Flared head  25  at shoulder  26  engages under notch  23  when inserted fully into housing component  30 . Once plug  10  is seated, internal sealing component  20  is pushed downward and engaged stably under notch  23  in housing component  30  which forms a receptacle for the sealing component. 
         [0018]    Referring now to  FIG. 3 , adapter  40  is shown removed from housing component  30  and about internal sealing component  20 . Adapter  40  is preferably attached to housing component  30  via reverse threading to facilitate later removal, meaning that turning to the right loosens and turning to the left tightens. Once the normal BOP testing is complete, adapter  40  may be right screwed and removed from engagement to housing component  30 . Virtually any form of engagement between adapter  40  and housing  30  may alternately be employed including traditional threading, pins, or other releasable engagement. Internal sealing component  20  remains as it is engaged via notch  23  as previously described.  FIG. 3  shows adapter  40  after being removed from test plug  10 . At this time the rig can remove this section from the well and continue operations while shear ram testing can continue with the drillable section remaining in the hole. The test pressure acts on top of the whole area of the plug increasing grip and sealing capability as the test pressure increases. After the bottom hole assembly is made up and the shear ram testing is complete it can run in the hole, drill out the plug and continue on to drill the hole. When one desires to remove test plug  10  from the shaft of a well bore, the test pipe is removed as previously described by right turning adapter  40  and disengaging it from the housing component  30 , permitting a drill bit to go down the hole and drill out the remaining plug, comprised of housing component  30 , internal sealing component  20  and ball check valve  24  which are made of elastomer and plastic. 
         [0019]    Referring now to  FIG. 4 , there is shown a cross sectional view of  FIG. 5 , along lines  4 - 4 . In  FIGS. 4 and 5 , a series of radial ports  65  are depicted. According to the embodiment shown in  FIG. 4 , radial ports  65  extend about the outer circumference to the inside diameter of housing component  30 . These ports permit the upward flow of fluid upon insertion of the plug and allow for pressure equalization before testing. 
         [0020]    Referring now to  FIGS. 4 and 5 , radial fins  70  are disposed about the periphery of the deformable outer portion of housing component  30  and are composed of a soft elastomer material  72  interspersed between smaller hard plastic regions which comprise radial fins  70 , generally in the area between elastomer material  72 , shown in  FIG. 5 . Radial fins  70  are comprised of a region of somewhat stiffer pie shaped wedges of material disposed between softer elastomer material  72 . The stiffer material may be molded into a preferred softer material that comprises a portion of housing component  30  during manufacture and may be situated radially about the central axis of housing component  30  at various lengths depending on user preference and desired stiffness required. The stiffer material may be pie shaped and disposed longitudinally along a length at the end within housing component  30  and in a preferred embodiment covered in part by a softer material. This combination of soft and hard material provides rigidity for pressure testing, but also allows the outer housing to conform to the inner diameter of the casing when inserted. In this way, test plug  10  is seated tight within the casing in a sealed arrangement as shown in  FIGS. 2 and 3 . As test plug  10  is inserted into an annulus, and pressure is disposed about test plug  10 , radial fins  70  extend outward to connect with the inner diameter of an annulus to establish a grip support. As pressure is exerted on the housing component  30 , and radial fins  70 , the housing component  30  is sealably engaged to the inner diameter of the annulus.  FIG. 4  also shows seal lip  75  which provides additional sealing engagement which improves with pressure between the housing component  30  and the inner diameter of the casing or annulus involved as shown in  FIGS. 2 and 3 . It is readily seen that upon engagement into the casing, fluid may flow upward through housing component  30  and expel through radial ports  65  before internal sealing component  20  is engaged and pressure testing is to begin. 
         [0021]    In operation, test plug  10  is lowered into a drill pipe until it reaches a desired location, such as the shear rams. Once test plug  10  has reached the desired location, pressure may be increased inside the drill pipe, preferably through drilling mud or water, preferably between 3,000 and 5,000 p.s.i. As pressure increases inside the drill pipe, radial fins  70  expand allowing test plug  10  to seal about the diameter of drill pipe. While placing the plug into the casing, fluids can flow upward through radial ports  65  shown in  FIG. 5 . Upon pressurization, internal sealing component  20  with flared head  25  and shoulder  26  engages under notch  23  when inserted fully into housing component  30 . Once the plug is seated, the internal sealing component  20  is pushed downward and engaged stably under notch  23  in housing component  30  which acts as a receptacle for internal sealing component  20 . When pressurizing the plug, the ball check valve  24  is forced down into the pocket in internal sealing component  20  to create a tight seal. After pressure testing is completed, adapter  40  is right screwed and removed leaving only destructible components made of elastomers and plastic. These are easily ground or deformed by a drill bit and flushed to the surface and removed. 
         [0022]    It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims. 
         [0023]    All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of various embodiments, it will be apparent to those of skill in the art that other variations can be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the issued claims.