Patent Publication Number: US-7219736-B1

Title: Externally testable redundant connections for subsea wells

Description:
FIELD 
   The present embodiments relate generally to testable connections. The present embodiments relate specifically to externally testable redundant connections for subsea wells. 
   BACKGROUND 
   The oil and gas industry utilizes a procedure known as “snubbing” in which a string of pipe is forced into a wellhole under pressure for various reasons, such as, to remove an obstruction that might exist in the well. In such cases, the wellhole usually has been drilled and a certain amount of casing has been set and blowout preventors or other ram apparatus have been installed at the wellhead to seal around the drill pipe or other pipe strings being inserted into the wellhole. These blowout preventers and ram-type apparatus seal around the string of pipe being snubbed into the well under pressure to prevent the pressurized fluid from escaping around the outside of the string of pipe. 
   In practice, the body of the individual segments of pipe comprising the string of pipe to be snubbed into the well usually are rack-tested hydrostatically or otherwise prior to use to make certain there are no leaks in the body of the pipe. However, as the connections between the various pipe segments are made-up and snubbed into the well, the connections are usually immediately subjected to high external pressures. The rack testing of the pipe segments will not reveal a leak that exists in a connection between two of the pipe segments. A leak in a connection creates a very hazardous working condition for all personnel involved as high-pressure fluid may flow from the inside of the wellhole, through the leak, upwardly through the string of pipe being snubbed into the well, and out onto the workmen. In addition, if corrective measures are required to correct the leak in a connection between the pipe segments after the string of pipe has been snubbed into the well, such corrective measures are expensive. 
   The oil and gas industry utilizes a procedure known as the work-over of a well in which a string of pipe is forced into a previously drilled well. The well is “live,” that is, contains fluid under pressure, below a certain depth but because of some obstruction, such as sand or concrete or the like, contains little or no pressurized fluid above that depth. When the tool on the end of the string of pipe breaks through the obstruction, the entire drill string, including the connections between the segments, is subject to the pressures of the well, which pressures can be intense. The same problems described above with respect to snubbing pipe into a completely live well, are applicable to this workover procedure. 
   A need exists for testable redundant connections for subsea wells that can sustain very high pressures. A need exists for testable redundant connections that can be safely tested in the field at very high pressures prior to use to ensure a good fluid tight connection 
   The present embodiments meet these needs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present embodiments will be explained in greater detail with reference to the appended Figures, in which: 
       FIG. 1  is a cross sectional view of an embodiment of the externally testable redundant connection with a test port plug. 
       FIG. 2  is a cross sectional view of the embodiment of the externally testable redundant connection depicted in  FIG. 1 , wherein the test port plug has been replaced with a test connector. 
       FIG. 3  is a detail of the inset “A” from  FIG. 1  and  FIG. 2  detailing the primary seal. 
       FIG. 4  is a detail of the inset “B” from  FIG. 1  and  FIG. 2  detailing the secondary seal. 
       FIG. 5  is a schematic depicting an embodiment of a method of use for the externally testable redundant connection. 
   

   The present embodiments are detailed below with reference to the listed Figures. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Before explaining the present embodiments in detail, it is to be understood that the embodiments are not limited to the particular embodiments herein and it can be practiced or carried out in various ways. 
   The present embodiments relate to connections, typically used for subsea wells. The connections are externally testable. The embodied connections utilize two seals to ensure environmental compliance and leak tight sealing. 
   In the embodied connections, the ferrule is crimped the tube to prohibit the rotation of the double jam nut, thereby preventing the double jam nut from vibrating loose from the tube. 
   Further, since the test port has a small diameter, the connection can sustain very high pressures and can be tested at very high pressures in the field prior to use to ensure a good fluid tight connection. 
   The embodied connections are easy to create and simple to install. The embodied connections are fast to manufacture and have high reliability due to the limited number of moving parts. 
   The connections can be used to isolate easily any leaks in a fluid system. Fluid comes out around the jam nut, comes out around the o ring, or goes into the tube for ease of detection during testing. 
   The double jam nut in the embodied connections is locking and cannot be unscrewed because of the ferrule. The ability to lock the double jam nut ensures that the jam nut does not vibrate loose during drilling or production. Further, the jam nut can be unscrewed and moved down the assembly without affecting the connection on the tube 
   An embodiment of an externally testable redundant connection for a subsea well includes a tube, connector assembly, a collar, and a secondary seal. The connector assembly includes a jam nut disposed over the tube; a ferrule disposed over the tube adjacent the jam nut; and a double jam nut. The double jam nut includes a test port and a double jam nut seal. The double jam nut is disposed over the tube adjacent to the ferrule. The test port is between the double jam nut seal and the ferrule. 
   The collar engages the tube and is used to transfer an axial force from the double jam nut. The collar compresses one end of the tube into a female profile, thereby forming a primary seal. The secondary seal is formed from a compression of the ferrule into the double jam nut using the jam nut. The secondary seal comprises a three contact points. 
   The externally testable redundant connection is adapted to receive a test fluid through the test port in order to determine if the primary seal and the secondary seal are providing a leak proof sealing engagement. 
   With reference to the figures,  FIG. 1  and  FIG. 2  depict is a cross sectional view of an embodiment of the externally testable redundant connection. 
   The embodied connections include a tube ( 90 ). The tube ( 90 ) can be comprised of durable materials, such as steel alloy, carbon steel, steel, and combinations thereof. Typically, the tube ( 90 ) has an outer diameter ranging from about ⅛ inch to about 1 inch. The first end ( 95 ) of the tube ( 90 ) can be coned or threaded. 
   The connector assembly is attached to the first end ( 95 ) of the tube ( 90 ). The connector assembly includes a jam nut ( 10 ), a ferrule ( 20 ), and a double jam nut ( 30 ). A jam nut ( 10 ) is disposed over the tube ( 90 ) as depicted in  FIG. 1  and  FIG. 2 . The jam nut ( 10 ) typically has an inner diameter ranging from about ⅛ inch to about 1 inch. The inner diameter provides a compressing engagement with the double jam nut ( 30 ). The compressing engagement is a threadable connection on the jam nut ( 10 ) adapted to engage a threadable connection of the double jam nut ( 30 ). 
   The ferrule ( 20 ) in the connector assembly is disposed over the tube ( 90 ) adjacent the jam nut ( 10 ). The ferrule ( 20 ) typically slidingly engages the double jam nut ( 30 ) and the female profile ( 80 ). An example of a ferrule ( 20 ) is a Swagelok™ or Parker™ model ferrules. The ferrule ( 20 ) can be adapted to crimp onto the tube ( 90 ) once the connector assembly is compressed by the jam nut ( 10 ). 
   The double jam nut ( 30 ) in the connector assembly has a test port ( 35 ) and a double jam nut seal ( 60 ). The double jam nut ( 30 ) is disposed over the tube ( 90 ) adjacent to the ferrule ( 20 ). The double jam nut seal ( 60 ) can be a locking double jam nut or an O-ring.  FIG. 1  and  FIG. 2  depict the embodiment wherein the double jam nut seal ( 60 ) is an O-ring. The double jam nut seal ( 60 ) can be formed by a second ferrule that seals against the double jam nut ( 30 ) and the female profile ( 80 ). 
   The test port ( 35 ) is between the double jam nut seal ( 60 ) and the ferrule ( 20 ). The test port ( 35 ) has an access hole with a diameter ranging from about 1/32 inch to about 1/16 inch. The test port ( 35 ) is typically a threadable engagement using metal to metal seals. The seals form a sealing engagement between a test fluid supply during seal testing and form a leak tight seal with a plug ( 40 ) when testing is complete.  FIG. 1  depicts the embodiment wherein a plug ( 40 ) is inserted into the test port ( 35 ). Alternatively, a removable and re-installable test connector ( 50 ) can be inserted into the test port ( 35 ).  FIG. 2  depicts the embodiment wherein a test connector ( 50 ) is inserted into the test port ( 35 ). 
   Continuing with  FIG. 1  and  FIG. 2 , the connection includes a collar ( 70 ). The collar ( 70 ) is typically formed from a durable material, such as carbon steel, steel, or a high nickel alloy steel. The collar ( 70 ) can include left handed threads to ensure that during the installation of the double jam nut ( 30 ) the rotation of the double jam nut ( 30 ) tightens the collar ( 70 ). The collar ( 70 ) engages the tube ( 90 ) and transfers axial forces from the double jam nut ( 30 ). In addition, the collar ( 70 ) compress the first end ( 95 ) into a female profile ( 80 ) forming a primary seal ( 15 ). 
     FIG. 3  is a detail of the primary seal ( 15 ) depicted in  FIG. 1  and  FIG. 2  as inset “A”. The primary seal ( 15 ) is preferably a metal to metal seal. The primary seal ( 15 ) has a primary sealing surface between the first end ( 95 ) and the female profile ( 80 ). The primary seal ( 15 ) is formed by deforming the first end ( 95 ) into the female profile ( 80 ) by compressing the double jam nut ( 30 ) through the collar ( 70 ). The primary seal ( 15 ) can sustain pressure from about 5000 psi to about 40,000 psi, preferably from about 15,000 psi to about 25,000 psi. 
     FIG. 4  is a detail of the secondary seal ( 25 ) depicted in  FIG. 1  and  FIG. 2  as inset “B”. The secondary seal ( 25 ) is formed by compressing the ferrule ( 20 ) into the double jam nut ( 30 ) using the jam nut ( 10 ). The secondary seal ( 25 ) has at least three contact points. The first contact point is between the double jam nut seal ( 60 ), the double jam nut ( 30 ), and the female profile ( 80 ). The second contact point is between the double jam nut ( 30 ) and the outer diameter of the ferrule ( 20 ). The third contact point is between the inner diameter of the ferrule ( 20 ) and the tube ( 90 ). 
   Similar to the primary seal ( 15 ), the secondary seal ( 25 ) is preferably a metal to metal seal. Alternatively, the secondary seal ( 25 ) can be an elastomeric seal. The secondary seal ( 25 ) can sustain pressure from about 5000 psi to about 40,000 psi. 
     FIG. 5  is a schematic depicting an example of making the embodied externally testable redundant connections. The method of making the connection begins by sliding a jam nut onto a first end of a tube (Step  100 ); sliding a ferrule into the tube adjacent the jam nut (Step  105 ); and sliding the double jam nut onto the tube. As discussed, the double jam nut can include a test port and a double jam seal (Step  110 ). 
   An end of the tube is coned and threaded (Step  115 ). A collar is threaded onto the tube (Step  120 ) and the tube is inserted into a female profile (Step  125 ). The double jam nut is threaded into the female profile (Step  130 ), whereby the collar is pushed axially by the double jam nut to deform the cone of the tube into the female profile creating a primary seal (Step  135 ). 
   Continuing with the example depicted in  FIG. 5 , the method continues by threadably engaging the jam nut into the double jam nut while maintaining the ferrule between the jam nut and the double jam nut (Step  140 ). Next, the jam nut is tightened, the ferrule is compressed, and the ferrule is deformed into the double jam nut while deforming the ferrule into the tube creating a portion of a secondary seal (Step  145 ). 
   The test port plug is removed (Step  150 ) and a pressure generating device is connected to the test port (Step  155 ). The pressure generating device can be a test pump that uses a test fluid, such as a Haskell pump or Enerpac pump. Examples of usable test fluids include nitrogen, helium, another gas, water, and hydraulic fluid. 
   The method ends by evaluating integrity of the primary seal and the secondary seal (Step  160 ); bleeding the pressure (Step  165 ); reinstalling the test port plug (Step  170 ); and running the connector into the well (Step  175 ). 
   While these embodiments have been described with emphasis on the preferred embodiments, it should be understood that within the scope of the appended claims the embodiments might be practiced other than as specifically described herein.