Patent Publication Number: US-2022213751-A1

Title: Coring device

Description:
TECHNICAL FIELD 
     The present invention relates to the technical field of core drilling, and especially to a coring device. 
     BACKGROUND ART 
     In the process of oilfield exploration, rock core is the key material for discovering oil and gas reservoir, as well as studying stratum, source rock, reservoir rock, cap rock, structure, and so on. Through the observation and study of the core, the lithology, physical properties, as well as the occurrence and characteristics of oil, gas, and water can be directly understood. After the oilfield is put into development, it is necessary to further study and understand the reservoir sedimentary characteristics, reservoir physical properties, pore structure, wettability, relative permeability, lithofacies characteristics, reservoir physical simulation, and reservoir water flooding law through core. Understanding and mastering the water flooded characteristics of reservoirs in different development stages and water cut stages, and finding out the distribution of remaining oil can provide scientific basis for the design of oilfield development plan, formation system, well pattern adjustment, and infill well. 
     Coring is to use special coring tools to take underground rocks to the ground in the process of drilling, and this kind of rock is called core. Through it, various properties of rocks can be determined, underground structure and sedimentary environment can be studied intuitively, and fluid properties can be understood, etc. In the process of mineral exploration and development, the drilling work can be carried out according to the geological design of strata and depth, and coring tools were put into the well, to drill out rock samples. 
     CONTENT OF THE INVENTION 
     The present invention is intended to provide a coring device, to realize the drilling, grasping and transferring of the core to the coring fidelity cabin. In order to realize the above objectives, the technical solutions adopted by the present invention are as follows: 
     A coring device comprises a core drilling tool, a core catcher, a rock core barrel, a drilling machine outer cylinder, a flap valve, and an inner rod for pulling the rock core barrel; the core catcher is provided inside the lower end of the rock core barrel, the core drilling tool includes an outer core tube and a hollow drill bit, the upper end of the outer core tube is connected to the lower end of the drilling machine outer cylinder, and the lower end of the outer core tube is connected to the drill bit; The lower end of the inner rod protrudes into the rock core barrel and is movable axially by a certain distance relative to the rock core barrel, the flap valve comprises a valve seat and a sealing flap, the valve seat is coaxially mounted on the inner wall of the drilling machine outer cylinder, and one end of the sealing flap is movably connected to the outer sidewall of the upper end of the valve seat; the top of the valve seat is provided with a valve port sealing surface matched with the sealing flap; 
     When the rock core barrel is located in the valve seat, the sealing flap opens 90° ; when the rock core barrel is lifted up to a certain height by means of the inner rod, the sealing flap returns to the top surface of the valve seat and is in sealing contact with the sealing surface of the valve opening. 
     Further, the core catcher comprises an annular base and a plurality of claws, the annular base is coaxially installed on the inner wall of the lower end of the rock core barrel, the claws are evenly arranged on the annular base, the lower end of the claws is connected with the annular base, and the upper end of the claws is retracted inward. 
     Further, the claw comprises a vertical arm and a tilt arm which are manufactured in one piece, the lower end of the vertical arm is connected with the annular base, the upper end of the vertical arm is connected with the lower end of the tilt arm, the upper end of the tilt arm is a free end, and the tilt arm tilts inward from bottom to top. 
     Further, the drill bit comprises an inner drill bit and an outer drill bit, the inner drill bit is installed in the outer drill bit, the lower end of the inner drill bit is provided with a first stage blade for drilling, and the outer sidewall of the outer drill bit is provided with a second stage blade for reaming. Further, a spiral groove is arranged on the outer wall of the outer core tube and the outer drill bit, and the spiral groove on the outer drill bit is continuous with the spiral groove on the outer core tube. Further, the first stage blade and the second stage blade on the drill bit are provided with coolant circuit holes. 
     Further, the rock core device also includes a trigger mechanism, that includes a trigger inner barrel and a trigger block. The side wall of the trigger inner barrel is provided with a through hole, the trigger block is placed in the through hole, and the outer sidewall of the bottom of the rock core barrel is provided with a convex part adapted to the trigger block. The inner wall of the drilling machine outer barrel is provided with a recessed opening which is matched with the trigger block. 
     The trigger block is located above the sealing valve flap, and the recessed opening is located above the trigger block; 
     When the rock core barrel is located in the valve seat, the inner trigger barrel is located between the rock core barrel and the drilling machine outer cylinder, the lower end of the inner trigger barrel is matched with the valve seat stop, the trigger block protrudes from the inner sidewall of the inner trigger barrel, and the sealing valve flap is located between the inner trigger barrel and the drilling machine outer cylinder. When the rock core barrel is raised to a certain height, the sealing flap returns to the top surface of the valve seat and is in sealing contact with the sealing surface of the valve opening, and the bottom of the trigger inner barrel presses on the sealing flap. 
     Preferably, 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 cylinder; the trigger spring is located above the trigger block. 
     Wherein, the outer sidewall of the lower part of the inner rod is provided with a limit step  1 , while the inner sidewall of the upper part of the rock core barrel is provided with a limit step  2  adapted to the limit step  1 . When the limit step  1  and the limit step  2  are against each other, the rock core barrel and the inner rod can no longer move axially. 
     Further, the bottom of the inner rod expands, and the outer wall of the expanding part of the inner rod is provided with a sealing ring  1 , which plays a sealing role with the inner wall of the rock core barrel. 
     Compared with the prior art, the present invention has the following beneficial effects: 
     1. The present invention can realize the core drilling, grasping and transferring to the coring fidelity cabin through the mutual cooperation of various parts, and can complete the core drilling with high stability, high performance, and high efficiency; 
     2. In the present invention, the drill bit is divided into two-stage blades, the bottom blade drills a small hole first, and then the upper blade expands the hole, so as to improve the drilling speed and the coring efficiency. The carbide sharp thin bit is used to cut the rock stratum, to reduce the disturbance of coring process to the formation and ensure the integrity and quality of coring; 
     3. A through hole is provided in the blade part as a coolant circuit hole, and the coolant can be sprayed out through the through hole to cool the blade, speed up the cooling rate of the blade, reduce the wear of the tool, and extend the life of the blade; 
     4. The outer wall of the outer core tube is provided with a spiral groove continuous with the drill bit, and as the outer core tube is screwed into the rock formation, the outer core tube creates a closed space for the coring tool, which can prevent the fidelity cabin from being contaminated; 
     5. In the present invention, the core catcher is a mechanical claw that faces upwards and is folded inward. When the claws go down, the claws are easily propped up by the core, so that the core enters the inner barrel; when the claws go up, it is difficult for claws to be stretched by the rock core, and because the rock core cannot resist the greater pulling force and the clamping action of the claws, the rock core is broken at the claws, and the broken core will continue to move up with the claws and remain in the inner barrel. The core catcher according to the present invention is easy to pull off hard rock, and solves the technical problem that the core catcher in the prior art can only take soft rock and is difficult to take hard rock; 
     6. When the flap valve is closed, the sealing flap is pressed by the falling trigger inner barrel, and the sealing-specific pressure is large, which can further improve the sealing performance of the valve. 
    
    
     
       DESCRIPTION OF FIGURES 
         FIG. 1 . Schematic diagram of the present invention before coring. 
         FIG. 2 . An enlarged view of A in  FIG. 1 . 
         FIG. 3 . An enlarged view of B in  FIG. 1 . 
         FIG. 4 . An enlarged view of C in  FIG. 1 . 
         FIG. 5 . Schematic diagram of the present invention during coring. 
         FIG. 6 . An enlarged view of A in  FIG. 5 . 
         FIG. 7 . An enlarged view of B in  FIG. 5 . 
         FIG. 8 . An enlarged view of C in  FIG. 5 . 
         FIG. 9 . Schematic diagram of the present invention after coring is completed. 
         FIG. 10 . An enlarged view of A in  FIG. 9 . 
         FIG. 11 . Sectional view of the drill bit. 
         FIG. 12 . Schematic diagram of the structure of the inner drill body. 
         FIG. 13 . Schematic diagram of the structure of the outer drill body. 
         FIG. 14 . 3D drawing of the core catcher. 
         FIG. 15 . Sectional view of the core catcher. 
         FIG. 16 . Schematic diagram of the flap valve. 
     
    
    
     In Figures:  1 -rock core barrel,  2 -inner rod,  3 -flap valve,  4 -drill bit,  5 -outer core tube,  6 -core catcher,  7 -expand,  8 -sealing ring  2 ,  9 -coolant circuit hole,  10 -spiral groove,  11 -convex part,  12 -sealing ring  1 ,  16 -drilling machine outer cylinder,  21 -limt step  1 ,  22 -limt step  2 ,  24 -spring sheet,  25 -recessed opening,  31 -valve seat,  32 -sealing flat,  41 -inner drill bit,  42 -outer drill bit,  51 -trigger spring,  52 -trigger inner barrel,  53 -trigger block,  61 -annular base,  62 -claws,  63 -ring sleeve,  121 - vertical arm,  122 -tilt arm,  241 -shaft,  242 -spring sheet,  311 -valve port sealing surface,  321 -groove,  322 -sealing ring  3 ,  411 -the first stage blade,  412 -inner drill body,  413 -the first stage blade installation slot,  421 -the second stage blade,  422 -outer drill body,  423 -the second stage blade installation groove,  424 - the first stage blade avoidance notch,  521 -shoulder. 
     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. 1-16 , the coring device disclosed in the present invention comprises a core drilling tool, a rock core barrel  1 , a core catcher  6 , a drilling machine outer cylinder  16 , a flap valve  3 , and an inner rod  2  for pulling the rock core barrel  1 ; the core catcher  6  is provided inside the lower end of the rock core barrel  1 , the core drilling tool comprises an outer core tube  5  and a hollow drill bit  4 , the upper end of the outer core tube  5  is connected to the lower end of the drilling machine outer cylinder  16 , and the lower end of the outer core tube  5  is connected to the drill bit  4 . 
     The lower end of the inner rod  2  protrudes into the rock core barrel  1  and is movable axially by a certain distance relative to the rock core barrel  1 . The bottom of the inner rod  2  is enlarged, and the outer wall of the enlarged portion  7  of the inner rod  2  is provided with a sealing ring  1   12 , which is in sealing engagement with the inner wall of the rock core barrel  1 . The lower outer sidewall of the inner rod  2  is provided with a limit step  1   21 , and the upper inner sidewall of the rock core barrel  1  is provided with a limit step  2   22  adapted to the limit step  1   21 . When the limit step  1   21  and the limit step  2   22  are against each other, the rock core barrel  1  and the inner rod  2  can no longer move axially. 
     In this specific example, the drill bit  4  is a PCD tool. As shown in  FIGS. 11, 12 and 13 , the drill bit  4  includes an inner drill bit  41  and an outer drill bit  42 , and the inner drill bit  41  includes a first-stage blade  411  and a hollow inner drill body  412 . The outer drill bit  42  includes a second-stage blade  421  and a hollow outer drill body  422 . As shown in  FIGS. 11 and 12 , the lower end of the inner drill body  412  is provided with a first-stage blade installation groove  413  for installing the first-stage blade  411 . The first-stage blade installation groove  413  is opened on the lower end surface of the inner drill body  412 , on which the first stage blade installation groove  413  is provided with a coolant circuit hole  9  that is an arc-shaped hole. The arc-shaped hole opens on the front end surface of the drill bit  4  and communicates with the first-stage blade installation groove  413 . The inner drill body  412  is provided with three first-level blade mounting grooves  413  at equal intervals in the circumferential direction, each first-level blade mounting groove  413  is provided with a coolant circuit hole  9 , and a first-stage blade  411  is installed in each first-level blade mounting groove  413 . 
     As shown in  FIGS. 11 and 13 , the outer wall of the outer drill body  422  is provided with a second-stage blade installation groove  423  for installing the second-stage blade  421 , and the second-stage blade installation groove  423  on the outer drill body  422  is provided with a coolant circuit hole  9 , the coolant circuit hole  9  is a bar-shaped hole, and the bar-shaped hole communicates with the second-stage blade installation groove  423 . The outer drill body  422  is provided with three second-level blade installation grooves  423  at equal intervals in the circumferential direction, and each second-level blade installation groove  423  is provided with a coolant circuit hole  9 , and a second-level blade  421  is installed in each second-level blade installation groove  423 . 
     As shown in  FIGS. 11, 12, and 13 , the inner drill  41  is installed inside the outer drill  42 , and the outer drill body  422  has a first-stage blade avoidance notch  424  at a position corresponding to the first-stage blade  411 . The first-stage blade avoidance notch  424  opens on the front end of the outer drill  42 . The cutting edge of the first-stage blade  411  is exposed from the outer drill body  422  by the first-stage blade avoidance notch  424 . The inner wall of the inner drill body  412  is provided with a second seal ring  8 , and the second seal ring  8  is located above the first-stage blade  411 . The second seal ring  8  is a highly elastic annular sealing ring. In the present invention, the drill bit is divided into two-stage blades. The first-stage blade  411  at the lower end first drills small holes, and then the second-stage blade  421  at the upper reams the hole, which can increase the drilling speed. A through hole is provided at the blade position as a cooling liquid circuit hole  9 , through which cooling liquid can be sprayed to cool the blade. 
     As shown in  FIGS. 4 and 13 , both the outer core tube  5  and the outer wall of the outer drill body  422  are provided with spiral grooves  10 , and the spiral groove  10  on the outer drill body  422  is continuous with the spiral groove  10  on the outer core tube  5 . The outer core tube  5  with the spiral groove  10  on the outer wall is equivalent to a spiral outer drill. As the outer core tube  5  is screwed into the rock formation, the outer core tube  5  creates a closed space for the coring tool. During the coring process, the second sealing ring  8  wraps the core, to ensure the isolation and quality preservation effect and achieve the goal of moisturizing and quality preservation. The present invention uses a hard alloy sharp thin bit to cut the rock formation, reduces the disturbance to the formation during the coring process, and ensures the integrity and quality of the coring. 
     As shown in  FIGS. 14 and 15 , the core catcher  6  includes an annular base  61  and a plurality of claws  62 . The claws  62  are evenly arranged on the annular base  61 . The lower ends of the claws  62  are connected with the annular base  61 , while the upper ends of the claws  62  are folded inward. There are  8 - 15  claws  62 , preferably  12  claws  62 . The number of claws  62  can be set as required, and is not limited to those listed above. 
     The claw  62  includes integrally manufactured vertical arm  121  and tilt arm  122 . The lower end of the vertical arm  121  is connected with the annular base  61 , while the upper end of the vertical arm  121  is connected with the lower end of the tilt arm  122 , and the upper end of the tilt arm  122  is a free end. The tilt arm  122  is inclined inward from bottom to top, and the inclination of the tilt arm  122  can be adjusted as required. In this example, the tilt angle of the tilt arm  122  is  60 ° , and the width of the claw  62  gradually decreases from bottom to top. 
     Wherein, the thickness of the pawl  62  is equal to the thickness of the annular base  61 , and the pawl  62  is manufactured integrally with the annular base  61 . The annular base  61  is sheathed with an annular sleeve  63 , and both of annular base  61  and annular sleeve  63  are fixedly connected. In particular, an annular groove adapted to the annular sleeve  63  is provided on the inner wall of the rock core barrel  1 , and the annular sleeve  63  is embedded in the annular groove with the free end of the claw  62  facing upward, and the free end of the claw  62  facing upward and inward. When the rock core passes through the hard claw  62  from bottom to top, it is easy to be stretched, while it is hard to be stretched when passing from top to bottom. 
     As shown in  FIGS. 3, 7, 10, and 16 , the flap valve  3  includes a valve seat  31  and a sealing valve flap  32 . The valve seat  31  is coaxially mounted on the inner wall of the drilling machine outer cylinder  16 . A sealing ring is arranged between the outer wall of the valve seat  31  and the inner wall of the drilling machine outer cylinder  16 , and the sealing ring is mounted on the outer wall of the valve seat  31 . One end of the sealing flap  32  is movably connected with the outer side wall of the upper end of the valve seat  31 , and the top of the valve seat  31  has a valve port sealing surface  311  matching the sealing flap  32 . When the rock core barrel  1  is located in the valve seat  31 , the sealing flap  32  is opened 90° and located between the rock core barrel  1  and the drilling machine outer cylinder  16 . When the rock core barrel  1  is lifted up to a certain height by the inner rod  2 , the sealing flap  32  returns to the top surface of the valve seat  31 , and is in a sealing contact with the valve port sealing surface  311 . 
     The outer periphery of the sealing flap  32  is provided with an annular groove for installing the third sealing ring  322 , and the third sealing ring  322  is installed in the annular groove. In the specific example, one end of the sealing flap  32  is hinged with the outer sidewall of the upper end of the valve seat  31  through the spring sheet  24 , in which the spring sheet  24  includes a rotating shaft  241  and an elastic sheet  242 . The top of the side wall of the valve seat  31  has a rotating shaft accommodating groove adapted to the rotating shaft  241 , and the outer surface of the sealing flap  32  has a groove  321  for receiving the elastic sheet  242 . The elastic sheet  242  is a curved steel sheet, which is stuck in the groove  321 , and the curved steel sheet can be straightened under the action of external force, and its curved surface can be turned into a plane and completely fit with the groove  321  on the outer surface of the sealing flap  32 . When the sealing flap  32  is opened by 90° , the inner surface of the sealing flap  32  and the outer wall of the trigger inner barrel  52  are a complete fit, moreover, the outer surface and the outer sidewall of the valve seat  31  are in the same cylindrical surface. The sealing flap  32  is a spatial curved surface obtained by cutting a semicircular tube piece with a conical surface or a spherical surface, and the outer diameter of the semicircular tube piece is consistent with the outer diameter of the valve seat  31 . 
     In another example, the sealing flap  32  is hinged with the outer sidewall of the upper end of the valve seat  31  through a pin shaft and a torsion spring. 
     In order to increase the sealing-specific pressure, the coring device also includes a trigger mechanism, that includes a trigger inner barrel  52 , a trigger spring  51 , and a trigger block  53 . A through hole is provided on the side wall of the trigger inner barrel  52 , and the trigger block  53  is placed in the through hole. The outer sidewall at the bottom of the rock core barrel  1  has a convex part  11  that fits with the trigger block  53 . The inner wall of the drilling machine outer cylinder  16  has a recessed opening  24  adapted to the trigger block  53 . The trigger block  53  is located above the sealing flap  32 , and the recessed opening  24  is located above the trigger block  53 ; the trigger spring  51  is sleeved outside the trigger inner barrel  52 , and the outer wall of trigger inner barrel  52  is provided with a shoulder  521 . The lower end of the trigger spring  51  is pressed against the shoulder  521 , while the upper end of the trigger spring  51  is pressed against the step surface of the drilling machine outer cylinder  16 , and the trigger spring  51  is located above the trigger block  53 . 
     As shown in  FIGS. 1, 3, 5, and 7 , when the rock core barrel  1  is located in the valve seat  31 , the trigger inner barrel  52  is located between the rock core barrel  1  and the drilling machine outer cylinder  16 . The lower end of the trigger inner barrel  52  matches the stop of the valve seat  31 , and the trigger block  53  protrudes outside from the inner side wall of the trigger inner barrel  52 . The outside of the trigger block  53  is in contact with the inner wall of the drilling machine outer cylinder  16 , while the inside of the trigger block  53  is in contact with the outer wall of the rock core barrel  1 . The sealing flap  32  is opened by 90° and is located between the inner trigger barrel  52  and the drilling machine outer cylinder  16 . 
     As shown in  FIGS. 9 and 10 , when the rock core barrel  1  is lifted up over the flap valve  3 , the convex part  11  at the bottom of the rock core barrel  1  drives the trigger block  53  to rise, and then drives the trigger inner barrel  52  to rise, and then drives the trigger inner barrel  52  to compress the trigger spring  51  and rise. When the bottom of the trigger inner barrel  52  passes the sealing flap  32 , the elastic sheet  242  clamped between the drilling machine outer cylinder  16  and the sealing flap  32  releases its elastic force, and the sealing flap  32  reverses under the elastic force of the elastic sheet  242  and its own gravity, and returns to the top surface of the valve seat  31 , and is in sealing contact with the valve port sealing surface  311 . A sealing fit is achieved with the valve seat  31 . When the trigger block  53  continues to rise with the rock core barrel  1  and reaches the recessed opening  25  of the drilling machine outer cylinder  16 , the trigger block  53  can be displaced radially and then separated from the role of the convex part  11  of the rock core barrel  1 . When the bottom of the rock core barrel  1  passes the recessed opening  25 , the trigger block  53  loses the force of the rock core barrel  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 sealing flap  32 , applying the sealing-specific pressure to the sealing flap  32 . 
     As shown in  FIGS. 1-4 , before the coring work starts, the rock core barrel  1  is located in the valve seat  31 , the lower end of the rock core barrel  1  extends into the drill bit  4 , and the lower end of the inner rod  2  extends toward the bottom of the rock core barrel  1 . At this time, the sealing flap  32  opens 90° , and the tight contact between the trigger inner barrel  52  and the sealing flap  32  can restrict the rotation of the sealing flap  32 . 
     As shown in  FIGS. 5-8 , as the drilling machine is lowered and runs, the rock core barrel  1  moves down with the drilling machine outer barrel  16 . As the drill bit  4  is drilled, the core enters the core barrel  1  and passes through the core catcher  6 . When the core gets through the hard claw  62 , the claw  62  will open and thus hold it tightly. Once the first limit step  21  and the second limit step  22  are against each other, the core barrel  1  and the inner rod  2  can no longer move relative to each other in the axial direction. The inner rod  2  moves to the top dead center relative to the core barrel  1 . 
     After stopping drilling, the inner rod  1  is pulled upwards. Because the first limit step  21  and the second limit step  22  conflict, the core tube  1  lifts up with the inner rod  1 , and the claw  62  moves upward with the core tube  1 . At this time, because the free end of the claw  62  is retracted, the claw  62  is difficult to be opened by the core. Because the core cannot resist larger pulling force and the free end of the claw  62  clamped inwards, the core is pulled and broken by the claw  62 . The broken core will continue ascending with the core catcher  6 , and thus remain in the core barrel  1 . As a preference, the inner wall of the core barrel  1  has a graphene coating. 
     When further rising to a certain height, the trigger inner barrel  52  loses its restrictive effect on the sealing flap  32 . Under the action of the spring, the sealing flap  32  returns to the top surface of the valve seat  31  and is in a sealing contact with the valve port sealing surface  311 , and the valve is closed. Finally, the falling trigger inner barrel  52  presses against the sealing flap  32  and applies a sealing-specific pressure to the flap valve  3 , thereby effectively avoiding the loss of liquid in the core barrel  1 . 
     The present invention can realize the core drilling, grasping and transferring to the coring fidelity cabin through the mutual cooperation of various parts, and can complete the core drilling with high stability, high performance, and high efficiency. 
     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.