Bidirectional circulation core guiding coring tool

Abstract

The invention belongs to the technical field of petroleum and natural gas drilling engineering, and discloses a two-way circulation core guiding coring tool which enables part of drilling fluid to flow into an inner barrel from the bottom of a shaft and conduct secondary circulation while achieving original normal major circulation of the drilling fluid. The inner barrel is arranged in the inner barrel, broken rock cores can enter the inner barrel easily, repeated cutting can be reduced, the drilling time needed for coring is shortened, friction between the rock cores entering the inner barrel and the inner barrel can be reduced, the rock cores are lifted to a certain degree, and the situation that the rock cores are accumulated at an inlet of the inner barrel and blocked is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of oil and natural gas drilling engineering, and in particular to a two-way circulation core guiding coring tool. Background Art

[0002] In the existing conventional self-locking coring tool, the flow direction of the drilling fluid is through the annular gap between the inner and outer barrels of the coring tool after the ball is dropped, through the drill bit water hole and the gap between the core claw and the drill bit to reach the bottom of the well. The drilling fluid then carries the cuttings through the annular space between the drill tool and the well wall to the wellhead. At this time, there is no obvious drilling fluid flow in the coring tool.

[0003] This drilling fluid circulation method is commonly used in current self-locking coring tools. It can be used normally when the formation in the coring section is well cemented and the core has good columnar properties. However, it has the following disadvantages when drilling into broken formations: (1) During coring, most of the drilling fluid can only flush and carry the cuttings at the bottom of the drill bit and near the outside of the drill bit back out of the wellhead. Some cuttings near the inside of the drill bit cannot be returned in time during drilling, resulting in repeated cutting during coring, which increases the drilling time required for coring. (2) When coring hard formations, too much cuttings accumulate at the entrance of the inner barrel, making it difficult for subsequent cores to enter the inner barrel, causing blockage. Summary of the invention

[0004] The purpose of the present invention is to provide a two-way circulation core guiding coring tool, which can change the flow direction of part of the drilling fluid, clean up the rock cuttings of the broken formation in time during normal coring, avoid repeated cutting, and prevent the core from accumulating at the inlet of the inner tube to cause core blockage.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A two-way circulation core guiding coring tool comprises an inner cylinder, an outer cylinder, a mandrel, a drill bit and a core claw, wherein the drill bit is axially connected to the outer cylinder, the mandrel and the inner cylinder are both located in the outer cylinder, an annulus is formed between the inner cylinder and the outer cylinder, the core claw is axially connected to the inner cylinder, the outer cylinder can rotate relative to the inner cylinder to drive the drill bit to rotate, and the two-way circulation core guiding coring tool further comprises a circulation mechanism located between the mandrel and the inner cylinder, and the circulation mechanism comprises:

[0007] Injection joints;

[0008] A flow divider joint, wherein the upper end of the flow divider joint is inserted into the injection joint and enclosed with the injection joint to form an injection cavity, and the lower end of the flow divider joint is inserted into the inner tube, and the flow divider joint is provided with a first flow channel and a second flow channel, wherein the first flow channel connects the injection cavity and the annulus, and the second flow channel connects the injection cavity and the inner tube;

[0009] A nozzle, connecting the mandrel and the injection chamber;

[0010] A diversion joint, located in the injection chamber and connected to the upper end of the diversion joint, so as to guide the drilling fluid sprayed from the nozzle into the first flow channel;

[0011] A filter joint is located in the inner tube and connected to the diversion joint, and the filter joint covers the inlet of the second flow channel.

[0012] Preferably, the spindle is rotatably connected to the outer cylinder.

[0013] Preferably, the inner diameter of the nozzle gradually decreases from one end close to the core shaft to the other end.

[0014] Preferably, the nozzle is located in the injection joint, and the injection joint includes a large diameter section and a small diameter section that are interconnected, one end of the small diameter section is connected to the core shaft, one end of the large diameter section is threaded with the diverter joint and encloses the injection chamber, and the nozzle is arranged between the large diameter section and the small diameter section.

[0015] Preferably, the circulation mechanism further comprises a pressure cap, which is located in the injection joint and is threadedly connected to the injection joint, and the pressure cap cooperates with the inner wall of the injection joint to axially limit the nozzle.

[0016] Preferably, a blind cavity is provided in the diverter joint, the blind cavity is open on one side facing the nozzle, the lower end of the drainage joint is inserted into the blind cavity and threadedly connected to the diverter joint, the upper end of the drainage joint protrudes from the diverter joint, and the first flow channel is connected to the blind cavity.

[0017] Preferably, a plurality of second flow channels are arranged around the blind cavity.

[0018] Preferably, it further includes a safety joint, which is connected to the outer tube, an upper stabilizer is connected between the outer tube and the safety joint, a lower stabilizer is connected between the outer tube and the drill bit, and annular protrusions of the same size are arranged on the outer walls of the upper stabilizer and the lower stabilizer.

[0019] Preferably, the filter joint is configured to be in a hollow cylindrical shape, and filter holes are provided on the side wall of the filter joint and on an end surface away from the diversion joint.

[0020] Preferably, during coring, the drilling fluid flow rate in the mandrel is above 30 L / s.

[0021] The beneficial effects of the present invention are as follows: the bidirectional circulation core guiding coring tool of the present invention can realize the original normal large circulation of the drilling fluid while allowing part of the drilling fluid to flow from the bottom of the wellbore into the inner barrel and perform a secondary circulation. In the process of the drilling fluid entering the inner barrel, it helps the broken core to enter the inner barrel, which can reduce repeated cutting and reduce the drilling time required for coring. Moreover, for the core that has entered the inner barrel, it can reduce the friction between the core and the inner barrel, and has a certain lifting effect on the core, thereby avoiding the accumulation of the core at the inlet of the inner barrel to cause core blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 2 is a schematic structural diagram of a bidirectional circulation core guiding coring tool according to an embodiment of the present invention;

[0023] Figure 2 yes Figure 1 Sectional view along AA direction;

[0024] Figure 3 It is a main structural schematic diagram of the circulation mechanism in the embodiment of the present invention.

[0025] In the figure:

[0026] 1. Safety joint; 2. Sealing ring; 3. Bearing box; 4. Mandrel; 5. Bearing; 6. Pressure cover; 7. Injection joint; 8. Pressure cap; 9. Nozzle; 10. Drainage joint; 11. Diverter joint; 11a. First flow channel; 11b. Second flow channel; 12. Filter joint; 13. Upper centralizer; 14. Inner tube; 15. Outer tube; 16. Lower centralizer; 17. Connecting sleeve; 18. Clamp seat; 19. Drill bit. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0028] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0031] refer to Figure 1-Figure 3 As shown, in the embodiment of the present invention, a bidirectional circulation core guiding coring tool is proposed, which is a component of a drilling tool. The tool includes an inner cylinder 14, an outer cylinder 15, a mandrel 4, a circulation mechanism, a drill bit 19 and a core claw (not shown in the figure), wherein the drill bit 19 is axially connected to the outer cylinder 15, the core claw is axially connected to the inner cylinder 14, the inner cylinder 14 is located inside the outer cylinder 15 and forms an annular space (hereinafter referred to as annulus) between the outer cylinder 15, and the outer cylinder 15 can rotate relative to the inner cylinder 14 to drive the drill bit 19 to rotate. The spindle 4 and the circulation mechanism are also located in the outer tube 15, and the circulation mechanism is located between the spindle 4 and the inner tube 14, including a nozzle 9, an injection joint 7, a drainage joint 10, a diverter joint 11 and a filter joint 12. The injection joint 7 is connected to the spindle 4 through the nozzle 9. The upper end of the diverter joint 11 is inserted into the injection joint 7 and enclosed with the injection joint 7 to form an injection chamber, and the lower end is inserted into the inner tube 14. The diverter joint 11 is provided with a first flow channel 11a and a second flow channel 11b. The first flow channel 11a connects the injection chamber and the annulus, and the second flow channel 11b connects the injection chamber and the inner tube 14. The drainage joint 10 is located in the injection chamber and is connected to the upper end of the diverter joint 11. The drainage joint 10 can introduce the drilling fluid sprayed into the injection chamber by the nozzle 9 into the first flow channel 11a. The filter joint 12 is located in the inner tube 14 and is connected to the lower end of the diverter joint 11. The filter joint 12 sets the outlet of the second flow channel 11b therein.

[0032] The circulation flow process of the drilling fluid in the above-mentioned circulating core guiding tool is as follows: the drilling fluid in the mandrel 4 enters the nozzle 9 to form a jet, the jet quickly passes through the injection cavity and is injected into the drainage joint 10, enters the annulus through the first flow channel 11a and reaches the bottom of the drill bit 19 to participate in normal circulation; a negative suction effect can be generated around the jet, under which the drilling fluid entering the inner cylinder 14 continuously flows from bottom to top, enters the injection joint 7 through the second flow channel 11b, and is continuously drawn into the jet to participate in secondary circulation. Since the drilling fluid in the inner cylinder 14 and the core enter the inner cylinder 14 in the same direction, the drilling fluid in the inner cylinder 14 can carry the secondary rock debris generated by the collision between the rock debris inside the drill bit 19 and the crushed rock debris in the inner cylinder 14 and move upward to the upper part of the inner cylinder 14. After being filtered by the filter joint 12, the rock debris with small particle size participates in normal circulation, and the rock debris with large particle size stays in the upper part of the inner cylinder 14, and can be taken out together with the core when the core is taken out.

[0033] The drilling fluid brings the cuttings into the inner tube 14, so that the cuttings can leave the bottom of the well in time, reducing the chance of repeated cuttings by the drill bit 19, and can reduce the friction resistance of the cuttings when entering the inner tube 14 when flowing upward, and has a certain lifting effect on the core, so that the core located at the entrance of the inner tube 14 can smoothly enter the inner tube 14, reducing the probability of core blockage and improving the core recovery rate of broken formations.

[0034] It should be emphasized that in order to prevent core erosion during coring drilling, small displacement drilling is generally adopted. The core of hard and broken formations has poor columnarity and is distributed in independent hard small pieces. Drilling fluid with large displacement and fast flow rate will not cause erosion of broken cores, but has a better effect on cleaning rock cuttings at the bottom of the rock. Therefore, the bidirectional circulation core guide coring tool in this embodiment is more suitable for hard and broken formations.

[0035] In order to generate high-pressure jets, the pump can be turned on normally during the drilling process and before reaching the bottom of the well. When drilling, the displacement of the drilling fluid needs to be increased. Under the premise of stable well wall, a relatively large drilling fluid flow rate can form a larger negative pressure difference, thereby achieving a better two-way circulation effect. In this embodiment, it is necessary to ensure that the drilling fluid flow rate in the mandrel 4 is above 30L / s, so that the cuttings are brought into the inner tube 14 for a better effect.

[0036] refer to Figure 1 As shown, the bidirectional circulation core guiding coring tool in this embodiment further includes a safety joint 1, which is arranged on the side of the outer tube 15 away from the drill bit 19, that is, the upper end of the outer tube 15, for connecting the upper pipe section.

[0037] In this embodiment, the inner cylinder 14 and the spindle 4 are relatively stationary, that is, when the outer cylinder 15 rotates, the spindle 4 is stationary. Then, when the drill bit 19 rotates, the driving member that drives the drill bit 19 to rotate only needs to drive the outer cylinder 15 and the drill bit 19 to rotate, thereby reducing the rotational driving force required for the rotation of the drill bit 19 and reducing the coring cost. Exemplarily, a bearing 5 is arranged between the spindle 4 and the outer cylinder 15 to reduce the friction during rotation. Specifically, the bearing 5 is sleeved outside the spindle 4, and a bearing box 3 is also arranged between the bearing 5 and the outer cylinder 15. The upper end of the bearing box 3 is inserted into the safety joint 1 and is screwed with the safety joint 1. A sealing ring 2 is arranged at the lower end face of the safety joint 1 to be sealed and connected with the bearing box 3. The upper end of the spindle 4 is inserted into the bearing box 3.

[0038] Furthermore, in order to prevent the bearing 5 from being separated from between the spindle 4 and the bearing box 3, the bidirectional circulation core guiding coring tool in this embodiment further includes a gland 6, the upper end of which is inserted into the bearing box 3 and screwed with the bearing box 3, and the upper end face of the gland 6 abuts against the lower end face of the bearing 5. At the same time, a first step surface is also provided on the inner wall of the bearing box 3, and the upper end face of the bearing 5 abuts against the first step surface.

[0039] In order to prevent the spindle 4 from escaping from the bearing box 3, a second step surface is provided on the inner wall of the bearing box 3, and a third step surface is provided on the outer wall of the spindle 4. The upper end surface of the spindle 4 can abut against the second step surface, and the third step surface on the spindle 4 can abut against the upper end surface of the bearing 5.

[0040] refer to Figure 1 and Figure 3 As shown, the injection joint 7 includes a large diameter section and a small diameter section that are interconnected, wherein one end of the small diameter section is connected to the core shaft 4, and one end of the large diameter section is threadedly connected to the diverter joint 11 to enclose a injection chamber, and the nozzle 9 is arranged between the large diameter section and the small diameter section, and the inner diameter gradually decreases from one end close to the core shaft 4 to the other end, so as to increase the pressure of the drilling fluid entering the injection chamber. In order to prevent the nozzle 9 from detaching from the injection joint 7, the inner wall of the connection between the large diameter section and the small diameter section of the injection joint 7 is set to a conical surface matching the shape of the nozzle, and the inner diameter gradually decreases from one end close to the core shaft 4 to the other end. At the same time, the circulation mechanism also includes a pressure cap 8, which is located in the small diameter section and is threadedly connected to the small diameter section. The upper end face of the nozzle 9 abuts against the lower end face of the pressure cap 8. With the cooperation of the pressure cap 8 and the inner conical surface of the injection joint 7, the axial limitation of the nozzle 9 can be achieved, so that the nozzle 9 is fixed relative to the injection joint 7.

[0041] In this embodiment, a blind cavity is provided in the flow diverter joint 11, and the blind cavity opens on one side facing the nozzle 9. The lower end of the drainage joint 10 is inserted into the blind cavity and screwed with the flow diverter joint 11, and the upper end protrudes from the flow diverter joint 11, so that the drilling fluid sprayed from the nozzle 9 can smoothly enter the blind cavity to play a drainage role. One end of the first flow channel 11a is connected to the blind cavity, and the other end passes through the side wall of the drainage joint 10 and is connected to the annulus, while the second flow channel 11b axially passes through the end faces of both ends of the flow diverter joint 11. Exemplarily, multiple first flow channels 11a and second flow channels 11b are provided, and multiple second flow channels 11b are provided around the blind cavity.

[0042] refer to Figure 1 As shown, the inner cylinder 14 and the core claw are connected by a clamp seat 18 to improve the efficiency of disassembly and assembly of the core claw. For example, the upper end of the clamp seat 18 is sleeved on the connecting sleeve 17 provided at the lower end of the inner cylinder 14, and the lower end is clamped with the core claw.

[0043] In order to prevent the drilling tool from deviating from the target direction, an upper stabilizer 13 is connected between the outer tube 15 and the safety joint 1, and a lower stabilizer 16 is connected between the outer tube 15 and the drill bit 19. The outer walls of the upper stabilizer 13 and the lower stabilizer 16 are both provided with annular protrusions that are the same size as the inner diameter of the wellbore.

[0044] In this embodiment, the filter joint 12 is configured to be a hollow cylindrical shape with one end open. The open end of the filter joint 12 is inserted into the diverter joint 11, and there is a gap between the filter joint 12 and the inner tube 14. The side wall of the filter joint 12 and the end face away from the diverter joint 11 are provided with filter holes. Relative to the filter screen, the fluid can pass through the end face of the filter joint 12 away from the diverter joint 11 and the side wall of the filter joint 12 and flow back into the injection chamber, which can increase the speed of the drilling fluid flowing back into the injection chamber, thereby improving the circulation efficiency.

[0045] The entire two-way circulation core guiding coring tool can make part of the drilling fluid flow from the lower end of the inner tube 14 to the upper end of the inner tube 14 and enter the injection chamber for repeated circulation, which helps to break the core into the tube and prevent core blockage. At the same time, it improves the cleanliness near the drill bit 19 and reduces secondary cutting.

[0046] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A two-way circulation core guiding coring tool, comprising an inner cylinder (14), an outer cylinder (15), a mandrel (4), a drill bit (19) and a core claw, wherein the drill bit (19) is axially connected to the outer cylinder (15), the mandrel (4) and the inner cylinder (14) are both located in the outer cylinder (15), an annulus is formed between the inner cylinder (14) and the outer cylinder (15), the core claw is axially connected to the inner cylinder (14), the outer cylinder (15) can rotate relative to the inner cylinder (14) to drive the drill bit (19) to rotate, and is characterized in that: The bidirectional circulation core guiding coring tool further comprises a circulation mechanism located between the mandrel (4) and the inner cylinder (14), wherein the circulation mechanism comprises: Injection connector (7); A flow dividing joint (11), the upper end of the flow dividing joint (11) is inserted into the injection joint (7) and enclosed with the injection joint (7) to form an injection cavity, the lower end of the flow dividing joint (11) is inserted into the inner tube (14), and the flow dividing joint (11) is provided with a first flow channel (11a) and a second flow channel (11b), the first flow channel (11a) connects the injection cavity and the annulus, and the second flow channel (11b) connects the injection cavity and the inner tube (14); A nozzle (9) connected between the mandrel (4) and the injection chamber; a diversion joint (10), located in the injection chamber and connected to the upper end of the diversion joint (11), so as to guide the drilling fluid sprayed by the nozzle (9) into the first flow channel (11a); A filter joint (12) is located in the inner tube (14) and connected to the flow diversion joint (11), and the filter joint (12) covers the outlet of the second flow channel (11b) therein.

2. The bidirectional circulation core guiding coring tool according to claim 1, characterized in that: The core shaft (4) is rotatably connected to the outer cylinder (15).

3. The bidirectional circulation core guiding coring tool according to claim 1, characterized in that: The inner diameter of the nozzle (9) gradually decreases from one end close to the core shaft (4) to the other end.

4. The bidirectional circulation core guiding coring tool according to claim 3 is characterized in that: The nozzle (9) is located in the injection joint (7), and the injection joint (7) comprises a large diameter section and a small diameter section which are interconnected, one end of the small diameter section is connected to the core shaft (4), and one end of the large diameter section is screwed to the diverter joint (11) to enclose the injection cavity, and the nozzle (9) is arranged between the large diameter section and the small diameter section.

5. The bidirectional circulation core guiding coring tool according to claim 4, characterized in that: The circulation mechanism further comprises a pressing cap (8), wherein the pressing cap (8) is located inside the injection joint (7) and is threadedly connected to the injection joint (7), and the pressing cap (8) cooperates with the inner wall of the injection joint (7) to axially limit the nozzle (9).

6. The bidirectional circulation core guiding coring tool according to claim 4, characterized in that: A blind cavity is provided in the diverter joint (11), the blind cavity is open on one side facing the nozzle (9), the lower end of the drainage joint (10) is inserted into the blind cavity and is screwed to the diverter joint (11), the upper end of the drainage joint (10) protrudes from the diverter joint (11), and the first flow channel (11a) is connected to the blind cavity.

7. The bidirectional circulation core guiding coring tool according to claim 6, characterized in that: A plurality of second flow channels (11b) are arranged around the blind cavity.

8. The bidirectional circulation core guiding coring tool according to any one of claims 1 to 6, characterized in that: It also comprises a safety joint (1), wherein the safety joint (1) is connected to the outer tube (15), an upper centralizer (13) is connected between the outer tube (15) and the safety joint (1), a lower centralizer (16) is connected between the outer tube (15) and the drill bit (19), and annular protrusions of the same size are arranged on the outer walls of the upper centralizer (13) and the lower centralizer (16).

9. The bidirectional circulation core guiding coring tool according to any one of claims 1 to 6, characterized in that: The filter joint (12) is configured in a hollow cylindrical shape, and filter holes are provided on the side wall of the filter joint (12) and on an end surface away from the diversion joint (11).

10. The bidirectional circulation core guiding coring tool according to any one of claims 1 to 6, characterized in that: When coring, the flow rate of the drilling fluid in the mandrel (4) is above 30 L / s.

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