Patent Publication Number: US-2022213750-A1

Title: Core barrel sealing structure capable of increasing sealing-specific pressure

Description:
TECHNICAL FIELD 
     The present invention relates to the technical field of coring equipment, and especially to a core barrel sealing structure capable of increasing the sealing-specific pressure. 
     BACKGROUND ART 
     At present, in the field of pressure keeping and coring, the upper end of the pressure keeping barrel is generally sealed by a piston, while the lower end of the pressure keeping barrel is usually sealed by a ball valve or a flap valve. The structure of the ball valve is relatively complex and the space occupied is large, which limits the diameter of the drilled core. The processing technology of the ball valve is demanding. When the pressure is high, the liquid in the pressure holding barrel will seep out from the gap between the ball valve and the core barrel, and thus a higher pressure can not be maintained. While, the existing flap valve can maintain a higher pressure, although the structure is simple, but its valve flap is a fixed shape, can not be deformed, and the success rate of matching is low. In addition, the sealing performance of flap valve is poor when the sealing-specific pressure is low. 
     CONTENT OF THE INVENTION 
     The present invention is intended to provide a core barrel sealing structure that can increase the sealing-specific pressure. A flap valve is used to perform lower end sealing, that has a deformable flap and a high success rate of matching. A trigger mechanism is added to increase the sealing-specific pressure and improve the sealing performance of the valve, when the flap valve is closed. 
     In order to realize the above objectives, the technical solutions adopted by the present invention are as follows: 
     A core barrel sealing structure that can increase sealing-specific pressure, that includes a core barrel, a drilling machine outer barrel, a chain mail-type flap valve, and a trigger mechanism. The chain mail-type flap valve includes a valve seat and a chain mail-type valve flap. The valve seat is coaxially installed on the inner wall of the drilling machine outer barrel. One end of the valve flap is movably connected with the outer sidewall of the upper end of the valve seat. The top of the valve seat has a valve opening sealing surface adapted to the valve flap; the valve flap includes an elastic sealing ring, elastic connecting strips, sealings, and a plurality of locking strips arranged in parallel; the elastic connecting strip connects all the locking strips in series, and the elastic sealing ring hoops all the locking strips together, to form an integral structure, and there is a sealing between two adjacent locking strips; 
     The trigger mechanism comprises a trigger inner barrel and a trigger block, and the side wall of the trigger inner barrel is provided with a through hole. The trigger block is arranged in the through hole. The outer sidewall of the bottom of the core barrel is provided with a protrusion that matches the trigger block. The inner wall of the drilling machine outer barrel is fitted with a recessed opening adapted to the trigger block. The trigger block is located above the valve flap, and the recessed opening is located above the trigger block. 
     When the core barrel is located in the valve seat, the trigger inner barrel is located between the core barrel and the drilling machine outer barrel. The lower end of the trigger inner barrel is matched with the valve seat stop, and the trigger block protrudes from the inner sidewall of the trigger inner barrel. 
     The valve flap is opened by 90° and is located between the trigger inner barrel and the drilling machine outer barrel. When the core barrel is lifted upwards to a certain height, the valve flap returns to a top face of the valve seat to make sealing contact with a sealing face of a valve opening, two adjacent locking strips are in sealing contact, and the bottom of the trigger inner barrel is pressed against the valve flap. 
     Further, the trigger mechanism also includes a trigger spring, that is sleeved outside the trigger inner barrel; the outer wall of the trigger inner barrel is provided with a shoulder, the lower end of the trigger spring is pressed against the shoulder, and the upper end of the trigger spring is pressed against the step surface of the drilling machine outer barrel; the trigger spring is located above the trigger block. 
     Wherein, the locking strip is provided with a groove adapted to the elastic sealing ring, and the elastic sealing ring is installed in the groove. 
     Further, when the valve flap is opened 90° , the locking strip is parallel to the axis of the valve seat. 
     Further, when the valve flap is in sealing contact with the valve seat, the valve flap has a circular flat structure. 
     Further, except for the two locking strips at the beginning and the end, one side of the other locking strips has a wedge-shaped through groove, and the opposite side has a convex part that fits with the wedge-shaped through groove; 
     One of the first and last locking strips is provided with a wedge-shaped through groove, while the other locking strip is provided with a convex part; 
     The convex part of one of the two adjacent locking strips is matched with the wedge-shaped through groove of the other, and the sealing element is arranged between the groove wall and the convex part of the wedge-shaped through groove. 
     Further, one of the wedge-shaped through grooves has the limit step surface  1  on the groove wall, while the convex portion of the corresponding locking strip has the limit step surface  2  that matches with the limit step surface  1 ; 
     When the valve flap is in sealing contact with the valve seat, the limit step surface  1  and the limit step surface  2  are located below the elastic sealing ring, the limit step surface  1  and the limit step surface  2  conflict, and the limit step surface  1  is located on the outside of limit step face  2 . 
     Wherein, the sealing element is installed on the groove wall of the wedge-shaped through groove. 
     Further, the valve flap is movably connected to the valve seat through a spring sheet, and the spring sheet includes a rotating shaft and an elastic sheet. The outer sidewall of the top end of the valve seat has a rotating shaft accommodating groove that matches the rotating shaft, in which the rotating shaft is installed. The outer surface of the valve flap is provided with an elastic sheet accommodating groove for accommodating the elastic sheet, in which the elastic sheet is installed. 
     Wherein, a sealing ring is arranged between the outer wall of the valve seat and the inner wall of the drilling machine outer barrel. 
     Compared with the prior art, the present invention has the following beneficial effects: 
     The core barrel sealing structure according to the present invention achieves lower-end sealing by means of the chain mail-type flap valve. When the valve is open, the chain mail-type flap valve is deformed and hidden between the core barrel and the drilling machine outer barrel, saving space and eliminating the restriction on the diameter of the drilled core. When the core barrel is raised to a certain height, the chain mail-type valve flap automatically closes, and the valve flap has a strong deformability, thus can automatically adjust a sealing matching position and has a high success rate of matching, with a reliable sealing performance. Moreover, the valve flap has a reverse self-locking property under pressure when the pressure is maintained. The valve flap also is pressed by the trigger inner barrel that has fallen back, such that the sealing-specific pressure is great, and the sealing performance thereof is reliable. 
    
    
     
       DESCRIPTION OF FIGURES 
         FIG. 1 . The structural diagram of the present invention when the chain mail-type flap valve is opened. 
         FIG. 2 . Enlarged view of A in  FIG. 1 . 
         FIG. 3 . Enlarged view of B in  FIG. 1 . 
         FIG. 4 . The structural diagram of the present invention when the chain mail-type flap valve is closed. 
         FIG. 5 . Enlarged view of A in  FIG. 4 . 
         FIG. 6 . Three-dimensional view of the chain mail-type flap valve with the core barrel in the valve seat. 
         FIG. 7 . The top view of the valve flap in  FIG. 6 . 
         FIG. 8 . A partial enlarged view of A in  FIG. 7 . 
         FIG. 9 . A partial enlarged view of A in  FIG. 8 . 
         FIG. 10 . Three-dimensional view of the valve flap in the natural state. 
         FIG. 11 . Three-dimensional view of the chain mail-type flap valve when the valve flap is closed. 
         FIG. 12 . Three-dimensional view of the valve flap when it is sealed under pressure. 
         FIG. 13 . The front view when the valve flap is sealed under pressure. 
     
    
    
     In Figures:  1 -core barrel,  2 -drilling machine outer barrel,  4 -spring sheet,  6 -drilling bit,  7 -core catcher,  8 - piston,  11 - convex part,  12 -ring groove,  21 -upper outer barrel,  22 -lower outer barrel,  23 - threaded connection sleeve,  24 - recessed opening,  31 -valve seat,  32 -valve flap,  41 -shaft,  42 -elastic sheet,  51 -trigger spring,  52 -trigger inner barrel,  53 -trigger block,  521 -shoulder,  201 -locking strip,  202 - elastic connecting strip,  203 -sealing element,  211 -wedge-shaped through groove,  212 -protruding part,  213 -limit step surface  1 ,  214 - limit step surface  2 ,  231 -sealing strip,  232 -metal seal,  233 -graphite,  234 -auxiliary seal,  311 -valve port sealing surface,  321 -elastic sheet accommodating groove,  322 -elastic sealing ring. 
     EXAMPLES 
     In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further illustrated hereinafter by combing with the attached Figures. As shown in  FIGS. 1, 2, and 6 , the core barrel sealing structure disclosed in the present invention that can increase sealing-specific pressure includes a core barrel  1 , a drilling machine outer barrel  2 , a chain mail-type flap valve, and a trigger mechanism. The chain mail-type flap valve includes a valve seat  31  and a chain mail-type valve flap  32 . The valve seat  31  is coaxially installed on the inner wall of the drilling machine outer barrel  2 . One end of the valve flap  32  is movably connected with the outer sidewall of the upper end of the valve seat. The top of the valve seat  31  has a valve opening sealing surface  311  adapted to the valve flap  32 . 
     The trigger mechanism comprises a trigger inner barrel  52  and a trigger block  53 , and the side wall of the trigger inner barrel  52  is provided with a through hole. The trigger block  53  is arranged in the through hole. The outer sidewall of the bottom of the core barrel  1  is provided with a protrusion  11  that matches the trigger block  53 . The inner wall of the drilling machine outer barrel  2  is fitted with a recessed opening  24  adapted to the trigger block  53 . The trigger block  53  is located above the valve flap  32 , and the recessed opening  24  is located above the trigger block  53 . 
     As shown in  FIGS. 1 and 2 , When the core barrel  1  is located in the valve seat  31 , the trigger inner barrel  52  is located between the core barrel  1  and the drilling machine outer barrel  2 . The lower end of the trigger inner barrel  52  is matched with the valve seat  31  stop, and the trigger block  53  protrudes from the inner sidewall of the trigger inner barrel  52 . The outer side of the trigger block  53  is in contact with the inner wall of the drilling machine outer barrel  2 , while the inner side of the trigger block  53  is in contact with the outer wall of the core barrel  1 . The valve flap  32  is opened by 90° and is located between the trigger inner barrel  52  and the drilling machine outer barrel  2 . 
     As shown in  FIGS. 4 and 5 , when the core barrel  1  is lifted upwards over the chain mail-type flap valve, the convex part  11  at the bottom of the core barrel  1  drives the trigger block  53  to rise, and then drives the trigger inner barrel  52  to rise. When the bottom of the trigger inner barrel  52  passes the valve flap  32 , the valve flap  32  reverses and returns to the top surface of the valve seat  31  to make sealing contact with the valve opening sealing surface  311 , and the chain mail-type flap valve is closed. 
     When the trigger block  53  reaches the recessed opening  24  of the drilling machine outer barrel  2  along with the core barrel  1 , the trigger block  53  can be displaced radially and then separated from the role of the protruding portion  11  of the core barrel  1 ; when the bottom of the core barrel  1  passes the recessed opening  24 , the trigger block  53  loses the force of the core tube  1  and triggers the inner barrel  52  to slide down under the action of gravity, and finally presses on the valve flap  32  to apply a sealing-specific pressure to the valve flap  32 . 
     In another embodiment, the trigger mechanism further includes a trigger spring  51 , and the trigger spring  51  is sleeved outside the trigger inner barrel  52 . The outer wall of the trigger inner barrel  52  is provided with a shoulder  521 , the lower end of the trigger spring  51  is pressed against the shoulder  521 , and the upper end of the trigger spring  51  is pressed against the step surface of the drilling machine outer barrel  2 ; the trigger spring  51  is located above the trigger block  53 . When the core barrel  1  is lifted upwards over the chain mail-type flap valve, the convex part  11  at the bottom of the core barrel  1  drives the trigger block  53  to rise, and then drives the trigger inner barrel  52  to compress trigger spring  51  and rise. When the bottom of the core barrel  1  passes the recessed opening  24 , the trigger block  53  loses the force of the core tube  1 , and the trigger inner barrel  52  drives the trigger block  53  to slide down under the action of the elastic force of the trigger spring  51  and its own gravity, and finally presses on the valve flap  32  to apply a sealing-specific pressure to the valve flap  32 . 
     Wherein, as shown in  FIG. 5 , the drilling machine outer barrel  2  includes an upper outer barrel  21 , a lower outer barrel  22 , and a threaded connection sleeve  23 . The lower end of the threaded connection sleeve  23  is provided with internal threads, while the upper end of the threaded connection sleeve  23  is provided with external threads. The upper end of the lower outer cylinder  22  is threadedly connected to the lower end of the threaded connection sleeve  23 , and the lower end of the upper outer cylinder  21  is threadedly connected to the upper end of the threaded connection sleeve  23 . 
     As shown in  FIGS. 5 and 6 , the outer wall of the valve seat  31  is provided with an annular groove  12  for installing a sealing ring, and the annular groove  12  is equipped with a sealing ring to realize the sealing cooperation between the valve seat  31  and the drilling machine outer barrel  2 . 
     The structure of the chain mail-type flap valve in this example is shown in  FIG. 6 . As shown in  FIGS. 7 and 8 , the valve flap  32  includes an elastic sealing ring  322 , an elastic connecting strip  202 , a sealing element  203 , and a plurality of parallel locking strips  201  in sequence. There are at least three locking strips  201 , and the number and size of the locking strip  201  are determined according to the size of the sealing surface of the valve port. The elastic connecting strip  202  connects all the locking strips  201  in series, and the elastic sealing ring  322  hoops all the locking strips  201  together to form an integral structure. The locking strip  201  is provided with a groove adapted to the elastic sealing ring  322 , in which the elastic sealing ring  322  is installed. A sealing element  203  is provided between two adjacent locking strips  201 . Since the multiple locking strips  201  arranged in parallel are connected in series by the elastic connecting strip  202  and tightly clamped by the elastic sealing ring  322 . When the valve flap  32  or the locking strip  201  receives an external force, the locking strip  201  and the elastic sealing ring  322  can be elastically deformed, and then two adjacent locking strips  201  can undergo relative displacement and rotation, so the valve flap  32  can be deformed when subjected to an external force. 
     As shown in  FIGS. 2, 6, and 7 , when the core barrel is located in the valve seat  31 , the valve flap  32  is opened 90° due to the force of the trigger inner barrel  52  on the core barrel  1 , and the double-sided force of the trigger inner barrel  52  and the drilling machine outer barrel  2  makes two adjacent locking strips  201  be opened. The valve flap  32  is deformed and finally hidden between the trigger inner barrel  52  and the drilling machine outer barrel  2 , and the inner surface of the valve flap  32  is completely attached to the outer side wall of the trigger inner barrel  52 , to save space and eliminate the restriction on the drilled core diameter. At this time, the locking strip  201  is parallel to the axis of the valve seat  31 . 
     As shown in  FIGS. 4 and 5 , when the core barrel  1  is lifted up to a certain height, the valve flap  32  returns to the top surface of the valve seat  31  and is in sealing contact with the valve port sealing surface  311 . Two adjacent locking strips  201  are also in sealing contact, thereby blocking the medium. 
     As shown in  FIGS. 7 and 8 , except for two locking strips  201  at the beginning and the end, one side of the other locking strips  201  has a wedge-shaped through groove  211 , and the opposite side has a convex portion  212  that is adapted to the wedge-shaped through groove  211 . One of the first and last locking strips  201  is provided with a wedge-shaped through groove  211 , and the other locking strip  201  is provided with a convex portion  212 ; the convex portion  212  of one  201  of two adjacent locking strips  201  is trapped in the wedge-shaped through groove  211  of the other locking strip  201 . The sealing element  203  is installed on the groove wall of the wedge-shaped through groove  211 . 
     As shown in  FIGS. 8 and 9 , the sealing element  203  is installed on one of the groove walls of the wedge-shaped through groove  211 , and the other groove wall of the wedge-shaped through groove  211  has the limit step surface  1   213 , while the convex portion  212  of the corresponding locking strip  201  has the limit step surface  2   214  that matches with the limit step surface  1   213 . When the valve flap  32  is in sealing contact with the valve seat  31 , the limit step surface  1   213  and the limit step surface  2   214  are located below the elastic sealing ring  322 , as well as the limit step surface  1   213  and the limit step surface  2   214  conflict, and the limit step surface  1   213  is located on the outside of limit step face  2   214 , to prevent the withdrawing of protrusion  212  from the wedge-shaped through groove  211  when the valve flap  32  is under pressure, so that it can be reversely self-locked when the pressure is maintained. 
     The sealing element  203  includes a sealing strip  231  for providing a soft seal, a metal seal  2032  for providing a hard seal, and two auxiliary seals  234 . The sealing strip  231  is installed between two auxiliary seals  234 , which fix the position of the sealing strip  231  and protect the sealing strip  231 . Preferably, the sealing element  203  also includes graphite  233 . The sealing strip  231  is located between graphite  233  and the metal seal  2032 , while graphite  233  is located inside the sealing strip  231 , and the graphite material can reduce the sliding resistance between the locking strips  201 . As the wall of wedge-shaped through groove  211  has a certain inclination, as shown in  FIGS. 7-13 , when closing, the locking strip  201  at the rear first contacts graphite  233  part of the locking strip  201  at the front, which reduces the friction and is conducive to the closing movement. Then, the sealing strip  231  performs the first sealing function, and the softer sealing strip  231  first meets the initial sealing conditions. The sealing strip  231  is a long strip with a circular cross section, and its length is consistent with the contact length of two adjacent locking strips  201 . As the pressure increases, the outer metal seal  2033  also realizes sealing, wherein the wedge-shaped through groove  211  can be V-shaped or trapezoidal, etc. 
     When the valve flap  32  contacts the valve port sealing surface  311 , the elastic sealing ring  322  is located in the middle of the valve flap  32 , the seal  203  is located above the elastic sealing ring  322 , and the elastic connecting strip  202  is located above the seal  203 . Due to the pressure of the elastic connecting strip  202  and the elastic sealing ring  322 , the valve flap  32  tends to become a flat plate structure in the natural state. However, due to the blocking effect of the seal  203 , the valve flap  32  is a micro-arc plate structure in the natural state, as shown in  FIG. 10 . However, when the valve flat  32  is pressurized and in sealing contact with the valve seat  31 , as shown in  FIGS. 11, 12, and 13 , two adjacent locking strips  201  squeeze the sealing element  203  to achieve their sealing contact, and the valve flap  32  is deformed into a circular flat structure. At the same time, the elastic sealing ring  322  realizes the sealing between the valve flat and the valve seat. 
     As shown in  FIGS. 2 and 11 , the valve flat  32  is movably connected to the valve seat  31  through a spring sheet  4 , which comprises a rotating shaft  41  and an elastic spring sheet  42 . The outer side wall of the top end of the valve seat  31  is provided with a rotating shaft holding groove matched with the rotating shaft  41 , and the rotating shaft  41  is installed in the rotating shaft holding groove. The outer surface of the valve flap  32  is provided with a spring sheet holding groove  321  containing the spring sheet  42 , and the spring sheet  42  is installed in the spring sheet holding groove  321 . The spring sheet  42  is a curved steel sheet, which is stuck at the spring sheet holding groove  321 . Under the action of external force, the curved steel sheet can be straightened, and its curved surface can be changed into a plane and fully fit with the spring sheet holding groove  321  on the outer surface of valve flat  32 . 
     In another embodiment, the valve flat  32  is hinged with the outer side wall of the upper end of the valve seat  31  by a pin and a torsion spring. 
     As shown in  FIGS. 1 and 3 , the inner wall of the lower end of the core barrel  1  is provided with a core catcher  7 , the upper part of the core barrel  1  is provided with a piston  8 , and the lower end of the drilling machine outer barrel  2  is connected with a drill bit  6 , as shown in  FIGS. 1 and 2 . In the core drilling stage, the lower end of the core barrel  1  passes through the valve seat  31  and extends to the bottom of the drilling machine outer barrel  2 , and at this time, the valve flap  32  opens 90° , the triggering inner barrel  52  is in a close contact with the valve flap  32 , which can limit the rotation of the valve flap  32 . With the drilling of bit  6 , the core enters into core barrel  1  from the lower end of core barrel  1  and is grasped by core catcher  7 . At this time, the in-situ water environment can invade into core barrel  1 . 
     When the core barrel  1  is lifted up, the core catcher  7  grabs the core and moves upward with the core barrel  1 . When the core barrel  1  is lifted to a certain height, the trigger inner barrel  52  loses the restriction effect on the valve flap  32 . Under the action of the spring, the valve flap  32  returns to the top surface of the valve seat  31  and is in sealing contact with the valve port sealing surface  311 , and thus the valve closes. Finally, the falling trigger inner barrel  52  presses on the valve flap  32  and applies the sealing-specific pressure to the valve flap  32 , so as to effectively avoid the liquid loss in core barrel  1 . 
     Of course, there are still many other examples of the present invention. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the invention, but these corresponding changes and deformations shall belong to the protection scope of the claims of the present invention.