CN108005603B

CN108005603B - flexible closed coring tool

Info

Publication number: CN108005603B
Application number: CN201711381288.1A
Authority: CN
Inventors: 张绍林; 孙强; 明尔扬; 李涛; 黄守志; 韩伟业; 陈强; 李益良
Original assignee: China Petroleum and Natural Gas Co Ltd
Current assignee: China Petroleum and Natural Gas Co Ltd
Priority date: 2017-12-20
Filing date: 2017-12-20
Publication date: 2019-12-10
Anticipated expiration: 2037-12-20
Also published as: CN108005603A

Abstract

the application discloses flexible airtight coring tool includes: the core drill bit mechanism and the flexible drill rod are connected in sequence; a core inner barrel penetrates through the flexible drill rod; the front end of the core inner cylinder is supported in the coring bit mechanism; the coring bit mechanism comprises a coring bit, a sealing head and a core claw; at least part of the obturator head is located within the coring bit; the core claw is positioned in the coring bit and sleeved outside the sealing head; the core gripper is arranged to only allow the sealing head to move backwards when subjected to a backward external force, and is arranged to fix the position of the sealing head when the sealing head is subjected to an external force in other directions or no external force; the flexible drill pipe comprises a first drill pipe joint, a second drill pipe joint and a plurality of drill pipe short sections which are connected end to end and located between the first drill pipe joint and the second drill pipe joint.

Description

Flexible closed coring tool

Technical Field

The application relates to the field of oil field exploration and development, in particular to a flexible closed coring tool.

Background

The exploration and development of oil fields need to accurately obtain important material data such as the original oil saturation of an oil layer, the formation porosity and the like so as to formulate a reasonable exploration and development scheme. In the middle and later stages of oil field development, the water injection effect needs to be checked, the oil-water dynamic of an oil layer, the water-flooded oil layer condition and the water displacement effect need to be quantitatively analyzed, effective potential excavation, synergism and yield increase measures are worked out, and a development scheme is perfected. Coring and core analysis are one of the most direct and main methods for acquiring oil and gas data and recognizing a reservoir, and can provide important basis for making and adjusting a development scheme.

Well drilling coring can be divided into conventional coring and special coring according to the purpose and operation mode of coring. Closed coring belongs to special coring, and means that a closed coring tool and a closed liquid are adopted to take out a rock core which is hardly polluted by free water of a drilling fluid under the condition of a water-based drilling fluid.

At present, the conventional closed coring tool has larger size, and has higher requirements on well track, drilling quality and the like when coring is carried out in horizontal well drilling. All the used closed coring tools of the horizontal well cannot be used in an ultra-short-radius horizontal well or a highly-deviated well with a sidetrack radius smaller than 3m, and the fixed-point and fixed-azimuth coring cannot be realized. In addition, the installation of the sealing head of the existing sealing coring tool needs to be fixed by a positioning pin, the installation structure is complex, and the manufacturing difficulty is high.

Disclosure of Invention

The present invention is directed to a flexible closed coring tool, which is adapted to solve at least one of the above problems.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

A flexible closed coring tool, comprising: the core drill bit mechanism and the flexible drill rod are connected in sequence; a core inner barrel penetrates through the flexible drill rod; the front end of the core inner cylinder is supported in the coring bit mechanism;

The coring bit mechanism comprises a coring bit, a sealing head and a core claw; at least part of the obturator head is located within the coring bit; the core claw is positioned in the coring bit and sleeved outside the sealing head; the core gripper is arranged to only allow the sealing head to move backwards when subjected to a backward external force, and is arranged to fix the position of the sealing head when the sealing head is subjected to an external force in other directions or no external force;

the flexible drill pipe comprises a first drill pipe joint, a second drill pipe joint and a plurality of drill pipe short sections which are connected end to end and are positioned between the first drill pipe joint and the second drill pipe joint; the flexible drill rod is connected with the coring bit mechanism through the first drill rod joint; and a preset angle can be bent between two adjacent drill pipe short joints.

as a preferred embodiment, the inner wall of the core claw is provided with a first latch inclining backwards, and the outer wall of the sealing head is provided with a second latch matched with the first latch; the second latch inclines forwards; the core claw can be radially expanded and reset.

As a preferred embodiment, the cross section of the core gripper is an open circular ring.

As a preferred embodiment, a fixing piece is further fixed at the rear end of the core inner cylinder; the fixing piece is used for keeping the position of the sealing head when the sealing head enters the inner core barrel.

as a preferred embodiment, the fixing member includes a permanent magnet block disposed at the rear end of the core inner cylinder; the closed head is made of a material which can be attracted by a magnet.

As a preferred embodiment, a first annular channel is arranged between the core inner cylinder and the flexible drill rod; the coring bit is provided with a fluid flow passage in communication with the first annular passage.

As a preferred embodiment, the rear end of the core inner barrel is further provided with a pressure balancing mechanism, and the pressure balancing mechanism is used for balancing the pressure inside the core inner barrel; a water passing sleeve is sleeved outside the rear end of the core inner cylinder; and a water passing channel is arranged on the wall of the water passing sleeve.

As a preferred embodiment, the pressure balance mechanism comprises a relief nut and an inner cylinder pressure balance piston; the fixing piece is arranged at the front end of the inner cylinder pressure balance piston; the unloading nut covers the rear end of the core inner cylinder; the front end of the inner cylinder pressure balance piston is positioned in the core inner cylinder and is in sealing fit with the wall of the core inner cylinder, and the rear end of the inner cylinder pressure balance piston penetrates through the load relief nut.

As a preferred embodiment, the pipe sub comprises:

The side wall of the ball tooth mechanism is provided with a first connecting part; a ball head structure is arranged at one end of the ball tooth mechanism, and a plurality of transmission teeth which are distributed at intervals along the circumferential direction of the ball head structure are arranged on the side wall of the ball head structure; a first sealing outer spherical surface is arranged behind the transmission gear; a second sealing outer spherical surface is arranged in front of the transmission gear;

The gear sleeve mechanism is movably connected with the spherical gear mechanism; the gear sleeve mechanism is provided with a movable space for accommodating the ball head structure; the rear end of the gear sleeve mechanism is sleeved outside the ball gear mechanism and is positioned behind the ball head structure; the lower part of the movable space is provided with a first sealing inner spherical surface matched with the second sealing outer spherical surface, and the upper part of the movable space is provided with a second sealing inner spherical surface matched with the first sealing outer spherical surface; a plurality of track grooves which are in one-to-one correspondence with the transmission teeth are arranged on the wall of the movable space; the transmission tooth part extends into the track groove; the transmission teeth are in contact with the bottom surface of the track groove; the gear sleeve mechanism is provided with a second connecting part which can be connected with the first connecting part.

as a preferred embodiment, the transmission gear and the ball head structure are an integrally formed structure; the transmission teeth extend along an arc line or an envelope line from top to bottom; the track groove is an arc-shaped groove.

In a preferred embodiment, the outer contour of the cross section of the transmission gear is a partial circular arc; the diameter of the outer contour of the cross section of the transmission gear is increased from top to bottom and then reduced.

As a preferred embodiment, the maximum diameter position of the outer contour of the cross section of the driving tooth is closer to the rear end of the driving tooth relative to the front end of the driving tooth; the first sealing outer spherical surface and the second sealing outer spherical surface are positioned on the same sphere; the maximum diameter position and the sphere center of the sphere are positioned on the same cross section.

In a preferred embodiment, at least one of the first sealing outer spherical surface and the first sealing inner spherical surface, and/or at least one of the second sealing outer spherical surface and the second sealing inner spherical surface is provided with an annular lubricating oil groove; and high-temperature-resistant lubricating grease is filled in the lubricating oil groove.

As a preferred embodiment, the gear sleeve mechanism comprises a gear sleeve and an end cover; the gear sleeve is fixedly connected with the front end of the end cover and forms the movable space; the outer wall of the gear sleeve is provided with a first spherical surface structure; the rear end of the gear sleeve is connected with the end cover; the first sealing inner spherical surface and the track groove are arranged on the inner wall of the gear sleeve; the second sealing inner spherical surface is arranged at the front end of the end cover; the end cover is provided with the second connecting part; the rear end of the end cover is sleeved outside the front end of the spherical tooth mechanism and is provided with a second spherical structure matched with the first spherical structure.

Has the advantages that:

As can be seen from the above description, the flexible closed coring tool of the present invention is configured such that the core gripper is only configured to allow the sealing head to move backward when subjected to a backward external force, and is configured to fix the position of the sealing head when the sealing head is subjected to external forces in other directions or no external force, so that the sealing head can be positioned at the front end of the flexible closed coring tool only by matching the core gripper with the sealing head, without positioning a pin and forming a pin hole, and the installation is relatively simple.

Specific embodiments of the present invention are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the invention are not so limited in scope. The embodiments of the invention include many variations, modifications and equivalents within the spirit and scope of the appended claims.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic diagram of a flexible encapsulated coring tool according to one embodiment of the present application;

FIG. 2 is a cross-sectional view of FIG. 1;

Fig. 3 is an enlarged view of the structure of the core gripper and a portion of the sealing head of fig. 1.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1 to 3, a flexible closed core drilling tool according to an embodiment of the present invention is applied to, but not limited to, drilling operations for ultra-short radius sidetrack drilling of horizontal wells. In this embodiment, the flexible closed coring tool comprises a coring bit mechanism and a flexible drill rod which are connected in sequence; a core inner barrel 7 is arranged in the flexible drill rod in a penetrating manner; the front end of the core inner cylinder 7 is supported in the coring bit mechanism.

The coring bit mechanism comprises a coring bit 1, a sealing head 3 and a core claw 4; at least part of the sealing head 3 is located inside the core bit 1; the core claw 4 is positioned in the coring bit 1 and sleeved outside the sealing head 3; the core gripper 4 is arranged to only allow the sealing head 3 to move backwards when subjected to a backwards external force and to fix the position of the sealing head 3 when the sealing head 3 is subjected to an external force in the other direction or no external force.

The flexible drill rod comprises: a first pipe joint 5, a second pipe joint 11, and a plurality of pipe subs connected end-to-end between the first pipe joint 5 and the second pipe joint 11. The flexible drill rod is connected with the core bit mechanism through the first drill rod joint 5; and a preset angle can be bent between two adjacent drill pipe short joints.

As can be seen from the above description, in the flexible closed coring tool of the present embodiment, the core claw 4 is configured to only allow the closed head 3 to move backwards when being subjected to a backward external acting force, and is configured to fix the position of the closed head 3 when the closed head 3 is subjected to external acting forces in other directions or no external acting force, so that the closed head 3 can be positioned at the front end of the flexible closed coring tool only by matching the core claw 4 and the closed head 3, and the installation is relatively simple without positioning a pin and forming a pin hole.

Simultaneously, this flexible airtight coring tool is equipped with flexible drilling rod, and the predetermined angle of flexible between two adjacent drilling rod nipple joints of flexible drilling rod, thereby the crooked of a plurality of drilling rod nipple joints formation stack and make the flexible airtight coring tool of this embodiment can carry out the drilling operation of ultrashort radius sidetracking horizontal well.

Wherein, the maximum bendable angle between two adjacent drill pipe nipples can be 8 degrees. Specifically, the drill pipe sub comprises: the ball tooth mechanism 8 extends lengthways, and a first connecting part is arranged on the side wall of the ball tooth mechanism 8; a ball head structure 24 is arranged at one end of the ball tooth mechanism 8, and a plurality of transmission teeth 21 which are arranged at intervals along the circumferential direction of the ball head structure 24 are arranged on the side wall of the ball head structure 24; a first sealing outer spherical surface is arranged behind the transmission teeth 21; a second sealing outer spherical surface 19 is arranged in front of (below) the transmission teeth 21; the gear sleeve mechanism is movably connected with the spherical gear mechanism 8; the gear sleeve mechanism is provided with a movable space for accommodating the ball head structure 24; the rear end of the gear sleeve mechanism is sleeved outside the ball gear mechanism 8 and is positioned behind the ball head structure 24; the lower part of the movable space is provided with a first sealing inner spherical surface matched with the second sealing outer spherical surface 19, and the upper part of the movable space is provided with a second sealing inner spherical surface matched with the first sealing outer spherical surface; the wall of the movable space is provided with a plurality of track grooves 20 which are in one-to-one correspondence with the transmission teeth 21; the transmission teeth 21 partially extend into the track grooves 20; the transmission teeth 21 are in contact with the bottom surface of the track groove 20; the gear sleeve mechanism is provided with a second connecting part which can be connected with the first connecting part.

When a plurality of drill pipe short sections are connected end to form a flexible drill pipe, as shown in fig. 1, a spherical tooth mechanism 8 of one drill pipe short section extends into a tooth sleeve mechanism of the previous drill pipe short section from the front end of the previous drill pipe short section, so that a first connecting part of the drill pipe short section is matched with a second connecting part of the previous drill pipe short section to carry out transmission; similarly, when this drilling rod nipple is connected with a latter drilling rod nipple, the spherical teeth mechanism 8 of the latter drilling rod nipple is stretched into its tooth sleeve mechanism by this drilling rod nipple front end, makes the first connecting portion of the latter drilling rod nipple cooperate with the second connecting portion of this drilling rod nipple to carry out the transmission.

As can be seen from the above description, the drill pipe short sections form a bendable structure through the movable fit of the spherical tooth mechanism 8 and the tooth sleeve mechanism, so that the drill pipe short sections can be bent by themselves, and the bends formed by the plurality of drill pipe short sections are superposed to perform the drilling operation of the ultra-short radius side drilling horizontal well. Simultaneously, the driving tooth 21 of the drilling rod nipple that this embodiment provided is the fixed knot of ball tooth mechanism 8 constructs to cooperate through driving tooth 21 and orbit groove 20 and carry out the transmission, can reduce stress concentration, improve equipment's reliability.

Through flexible drilling rod and with flexible drilling rod adopt universal swing joint's drill bit, form a whole flexible chain, this kind of flexible chain is different with traditional crack elbow, the stand pipe that includes a plurality of trapezoidal pipe constitutions. The traditional gap bent pipe can be bent to be an approximate bent pipe only in one direction, the bent pipe does not show flexibility after being bent, but becomes a section of rigid bent pipe, once the outer edge of the rigid bent pipe is rubbed with the inner side of a well wall, the rigid bent pipe cannot be arched inwards by itself to avoid obstacles.

The flexible drill rod of the reverse viewing mode is characterized in that each section of the drill rod short section is movably connected with the gear sleeve mechanism through the spherical tooth mechanism 8, so that when any section of the drill rod short section is rubbed with a well wall, the section of the drill rod short section can be properly bent, obstacles are avoided, and a drill rod drill bit can smoothly run downwards without obstacles. For the flexible casing for well cementation, two adjacent sections of flexible casings are movably connected through the hinged telescopic pipe, and the flexible casings can be ensured to smoothly descend to a required position along a drilling well.

It should be noted that the front and rear directions and the up and down directions in the present invention are referred to the first tool joint 5, and the part of the two parts close to the first tool joint 5 is in front or below, and the part far from the first tool joint 5 is in back or above; for example, the direction from the first drill pipe joint 5 to the second drill pipe joint 11 is a front-to-rear direction or a bottom-to-top direction.

With continued reference to fig. 1, the button mechanism 8 extends lengthwise and is generally of a tubular structure. The first connecting portion is substantially disposed from the rear end (or rear end) to the ball head position in the length direction of the ball tooth mechanism 8. The ball structure 24 is located behind (or in front of) the first connection portion (with the reader facing fig. 1). The side wall of the ball head structure 24 is provided with a plurality of transmission teeth 21 which are arranged along the circumferential direction at intervals. A first sealing outer spherical surface is arranged behind the transmission teeth 21; and a second sealing outer spherical surface 19 is arranged in front of the transmission teeth 21.

In order to effectively improve the structural strength, the transmission gear 21 and the ball head structure 24 are integrally formed. Of course, the gear teeth 21 may be fixed to the outer surface of the ball head structure 24 by welding or the like. The transmission teeth 21 extend along an arc line or an envelope line from top to bottom; the track groove 20 is an arc-shaped groove. The outer contour of the cross section of the transmission gear 21 is a partial circular arc; the diameter of the outer contour of the cross section of the transmission gear 21 is increased from top to bottom and then reduced.

Through setting up such structure, both ends diameter is little about this driving tooth 21 forms, and the big circular arc envelope structure of middle part diameter is under the condition of receiving the big angle of axial force effect turn, and this driving tooth 21 still can transmit big moment of torsion, and can not produce obvious stress concentration, has the structural reliability of preferred. Meanwhile, the transmission teeth 21 of the arc-shaped structure are matched with the arc-shaped grooves to form a transmission pair, so that the stress area of the transmission pair at any angle of the flexible drill rod is unchanged, and the fatigue wear of a structural part can be effectively reduced.

Further, the maximum diameter position of the outer profile of the cross section of the gear teeth 21 is closer to the rear end of the gear teeth 21 than to the front end of the gear teeth 21. Specifically, the first sealing outer spherical surface and the second sealing outer spherical surface 19 are located on the same sphere; the maximum diameter position and the sphere center of the sphere are positioned on the same cross section.

In the present embodiment, the movable space of the sleeve gear mechanism can accommodate the ball gear mechanism 8. Wherein, the activity space and the ball head structure 24 can be arranged concentrically, so that the ball tooth mechanism 8 can swing universally, thereby forming a bending angle. The outer surface of ball head structure 24 is in abutting contact with the inner surface of the playing space.

For convenient sealing and drilling fluid leakage prevention, the lower part of the movable space is provided with a first sealing inner spherical surface matched with the second sealing outer spherical surface 19, and the upper part of the movable space is provided with a second sealing inner spherical surface matched with the first sealing outer spherical surface. Further, in order to ensure the flexibility of the drill rod in rotating and bending, at least one of the first sealing outer spherical surface and the first sealing inner spherical surface, and/or at least one of the second sealing outer spherical surface 19 and the second sealing inner spherical surface is provided with an annular lubricating oil groove 22; the lubricating oil groove 22 is filled with high temperature grease. As shown in fig. 1, the annular lubricating oil groove 22 has two (may also be referred to as two) coaxially arranged.

As shown in fig. 1 and 2, the bottom surfaces of the transmission teeth 21 and the track grooves 20 disposed on the outer wall of the ball head structure 24 both extend in an arc shape along the extending direction of the ball tooth mechanism 8 (or from top to bottom as shown in fig. 1), and the arc shapes of the transmission teeth 21, the track grooves 20 and the bottom surfaces thereof are matched with the contour line of the ball head structure 24 (for example, the transmission teeth, the track grooves 20 and the bottom surfaces thereof are concentrically disposed with different diameters). As shown in fig. 1, the contour line of the bottom surface of the gear 21 and the outer contour line of the ball head structure 24 are concentric circles.

As shown in fig. 1, one end of the driving tooth 21 extends into the track groove 20 and contacts the bottom surface of the track groove 20. When the ball head structure 24 rotates in the activity space, the transmission teeth 21 slide relative to the track groove 20, and in the sliding process, the transmission teeth 21 are always in contact with the bottom surface of the track groove 20, so that the ball head structure 24 and the activity space are concentrically arranged. Specifically, the number of the transmission teeth 21 is two and the transmission teeth are uniformly distributed along the circumferential direction; the number of the track grooves 20 is 6.

Specifically, the gear sleeve mechanism can comprise a gear sleeve 9 and an end cover 10. The gear sleeve 9 is fixedly connected with the front end of the end cover 10 and forms the movable space. The outer wall of the gear sleeve 9 is provided with a first spherical structure 23. The rear end of the gear sleeve 9 is connected with the end cover 10; the end cap 10 is provided with the second connecting portion. The rear end of the end cap 10 is provided with a second spherical structure 18 which is matched with the first spherical structure 23. In order to facilitate the rotation of the ball tooth mechanism 8, a taper hole which is communicated with the movable space is arranged at the rear end of the end cover 10; the end cover 10 is sleeved outside the ball tooth mechanism 8 through the taper hole; the diameter of the taper hole is gradually increased from bottom to top. Preferably, the inclination angle of the taper hole is 8 degrees.

The gear sleeve 9 and the end cover 10 are both of a sleeve type structure or a tubular structure as shown in fig. 1, so that the drill pipe nipple formed by the gear mechanism 8 and the end cover has a central flow passage. The gear sleeve 9 and the end cover 10 are arranged from top to bottom as shown in fig. 1. The gear sleeve 9 and the end cover 10 are matched to form a movable space, and the inner wall of the gear sleeve 9 is provided with the first sealed inner spherical surface and the track groove 20. The gear sleeve 9 is in threaded connection with the end cover 10. As shown in fig. 1, the second sealing inner spherical surface is disposed at the front end of the end cap 10; the rear end of the end cover 10 is sleeved outside the front end of the ball tooth mechanism 8 and is provided with a second spherical structure 18 matched with the first spherical structure 23.

As shown in fig. 1, the ball head structure 24 is interposed between the gear sleeve 9 and the end cap 10, and an upper surface of a reduced diameter protrusion of the end cap 10 forms the second sealing inner spherical surface, and a lower surface of the reduced diameter protrusion forms a step against which the rear end of the ball tooth mechanism 8 abuts. The second spherical structure 18 is disposed at the rear end of the end cap 10 and is an inner spherical surface. The first spherical structure 23 is disposed on the outer wall of the gear sleeve 9 and is an outer spherical surface. The first spherical structure 23 is in contact with the second spherical structure 18, and guides and assists the relative swing between the spherical tooth mechanism 8 and the gear sleeve mechanism, and simultaneously prevents dirt from entering the movable spherical surface between the end cover 10 and the ball head structure 24.

As shown in fig. 1, the end cover 10 is provided with a second connection portion, and both the second connection portion and the first connection portion may be of a threaded structure and be in threaded connection with (of the next drill pipe sub). Wherein, the second connecting part is positioned at the rear of the movable space and the rear of the reducing bulge. The ball tooth mechanism 8 is in threaded connection with the gear sleeve mechanism, so that torque transmission can be stably kept, and bending is conveniently generated between two adjacent drill pipe short sections.

Further, the gear sleeve 9 is in threaded connection with the end cover 10. The track grooves 20 are uniformly distributed along the circumferential direction of the ball head structure 24. Each of the track grooves 20 and the pin holes is provided with one of the transmission teeth 21. All the transmission teeth 21 are positioned on the same plane, so that bending of the drill rod short section can be met, and torque can be transmitted well. The number of the track grooves 20 is not less than 4. As shown in fig. 2, the number of track grooves 20 is 6, and the number of drive teeth 21 is also 6. The first connecting portion is an external thread, and the second connecting portion is an internal thread.

In one embodiment, the first tool joint 5 is also movably connected to the pipe sub, and the second tool joint 11 is also movably connected to the pipe sub. Specifically, as shown in fig. 1, one end of the first drill rod joint 5 is provided with a drill rod male buckle. The rear end of the first drill rod joint 5 is sleeved outside the front end of the ball tooth mechanism 8 and is provided with the second spherical structure 18. Further, as shown in fig. 1, a drill rod box is provided at the rear end of the second drill rod joint 11, and the front end of the second drill rod joint 11 is connected with a ball head structure 24.

In the present embodiment, the drill pipe nipple can be bent, that is, the gear sleeve mechanism and the spherical tooth mechanism 8 can swing relatively. Preferably, the degree of bendability of the drill pipe nipple is up to degree. By the arrangement, the drilling operation of an ultra-short radius sidetrack horizontal well or a highly-deviated well with a deflecting radius not more than 1.8 meters can be smoothly completed in an 51/2' (5 inch half) well.

In the present embodiment, the core inner tube 7 may be made of a titanium alloy. So, rock core inner tube 7 possesses higher elasticity, and the internal diameter is greater than 32mm, based on titanium alloy's resilience performance for rock core inner tube 7 can pass through by the homeotropic bending when making the oblique section, and the entering horizontal segment can kick-back naturally, guarantees that the rock core of getting gets into rock core inner tube 7 smoothly. When the drilling tool is lifted to pass through the deflecting section and the window after coring, the core inner barrel 7 can be bent to enter the main shaft and rebound, so that the lifting resistance and potential damage to the flexible closed coring tool are reduced. Through the core inner barrel 7 with the structure, the single coring length can be larger than 0.8m, and the diameter of the cored core is larger than 32 mm.

With continued reference to fig. 1, at least a portion of the sealing head 3 is within the core drill bit 1. The bit sub connects the rear end of the coring bit 1 with the first tool joint 5. The coring bit 1 is integrally of a pipe body structure, and the outer wall of the coring bit can be in arc transition towards the inner wall of the coring bit, so that drilling is facilitated. The sealing head 3 is inserted into the coring bit 1. The sealing head 3 may be of hollow construction to guide the core being drilled.

In this embodiment, as shown in fig. 3, a first latch 41 inclined backward is provided on an inner wall of the core gripper 4, and a second latch 31 engaged with the first latch 41 is provided on an outer wall of the sealing head 3; the second latch 31 is inclined forward; the core gripper 4 can be radially enlarged and reset. The first latch 41 of the core claw 4 can also anchor the core so as to shear the core off the stratum during coring.

Further, the cross section of the core claw 4 is an open circular ring. Specifically, the core claw 4 is of an open sleeve structure, so that the core claw can be expanded and contracted along the radial direction and reset. When the closing head 3 is subjected to a rearward force (thrust from the core during coring), the first catch 41 of the core gripper 4 is inclined rearward and, in cooperation with the second catch 31, only the closing head 3 is allowed to move rearward. In the process that the sealing head 3 moves backwards, the core claw 4 is subjected to expansion resetting after passing through one first latch 41 in the moving direction until the sealing head 3 enters the core inner cylinder 7 behind.

and a first annular channel is arranged between the core inner cylinder 7 and the flexible drill rod. The core bit 1 is provided with a fluid flow channel communicating with the first annular channel. In particular, the flow channels are provided in the wall of the core bit 1, the bit sub, to facilitate the flow of drilling fluid. As shown in fig. 1, the front end of the bit adapter is provided with external threads and internal threads. The front end of the drill bit joint extends into the coring bit 1 and is in threaded connection with the coring bit 1. In order to prevent drilling fluid from entering the core inner cylinder 7, the sealing head 3 is also sleeved with a sealing gasket 2.

In the present embodiment, the core drill mechanism may further include a suspension mechanism that supports the front end of the core inner tube 7. The suspension mechanism is positioned in the coring bit mechanism; one end of the sealing head 3 extends into one end of the suspension mechanism, and the other end of the suspension mechanism is connected with the coring inner cylinder; the sealing head 3 can slide into the coring inner cylinder; the suspension mechanism can prevent the rotation of the coring bit mechanism from being transmitted to the coring inner cylinder. In particular, the suspension mechanism comprises a bearing assembly 6.

In the present embodiment, the bearing assembly 6 may include a bearing (e.g., a tapered roller bearing), and a bearing housing. The bearing is fixed in the bearing sleeve, and the bearing sleeve is sleeved in the drill bit joint (the coring bit 1) and sleeved outside the front end of the core inner cylinder 7.

Further, in order to prevent the closed head 3 from falling under the action of an external force or gravity in the process of lifting the drilling tool and causing impact on the collected rock core, even the rock core foundation rock core inner cylinder 7 is fixed with a fixing piece 12 at the rear end of the rock core inner cylinder 7; the fixing element 12 is used to maintain the position of the sealing head 3 when the sealing head 3 enters the core inner barrel 7.

Specifically, the fixing piece 12 comprises a permanent magnet block arranged at the rear end of the core inner cylinder 7; the sealing head 3 is made of a material that can be attracted by a magnet. After the sealing head 3 enters the rock core inner cylinder 7, the permanent magnet blocks are adsorbed on the permanent magnet blocks due to the magnetic force of the permanent magnet blocks, so that the position of the sealing head 3 is relatively fixed, and the rock core cannot be pushed in the lifting process.

As shown in fig. 1, a pressure balancing mechanism is further disposed at the rear end of the core inner cylinder 7, and the pressure balancing mechanism is used for balancing the pressure inside the core inner cylinder 7; a water passing sleeve 14 is sleeved outside the rear end of the core inner cylinder 7; the wall of the water passing sleeve 14 is provided with a water passing channel. The water jacket 14 can effectively filter the circulating drilling fluid. A sliding bearing 15 can be arranged between the water passing sleeve 14 and the core inner cylinder 7, so that the core inner cylinder 7 is righted through the sliding bearing 15.

Specifically, the pressure balance mechanism comprises a load relief nut 16 and an inner cylinder pressure balance piston 13. The fixing piece 12 is arranged at the front end of the inner cylinder pressure balance piston 13; the unloading nut 16 covers the rear end of the core inner cylinder 7; the front end of the inner cylinder pressure balance piston 13 is positioned in the core inner cylinder 7 and is in sealing fit with the wall of the core inner cylinder 7, and the rear end of the inner cylinder pressure balance piston 13 penetrates through the load relief nut 16. In order to further balance the pressure of the core inner cylinder 7, the rear end of the pressure balance piston 13 is provided with an overflow valve 17 (fig. 1 is only schematic in nature).

The coring process using the flexible closed coring tool of the above embodiment will be described in detail below: (1) windowing and sidetracking at the design position of the shaft, and drilling to the design coring position; (2) lowering the flexible closed coring tool of the present embodiment to a coring position; (3) circulating drilling fluid outside the well, slowly starting rotary power, and cleaning rock debris precipitated at the bottom of the well by the drilling fluid through a first annular channel and a fluid flow channel; (4) increasing the bit pressure outside the well, and starting to drill a coring bit mechanism; (5) the sealing head 3 is pushed into the inner core barrel 7 by the core; (6) the core enters the core inner cylinder 7 under the guidance of the sealing head 3, meanwhile, the sealing head 3 extrudes sealing liquid in the core inner cylinder 7, the sealing liquid overflows to the core position through the sealing head 3, and the core is wrapped; (7) the coring bit mechanism continuously drills a core, and the sealing liquid in the core inner cylinder 7 continuously wraps the core until the core with enough length is drilled; (8) a drilling tool is lifted from a well mouth, the whole flexible closed coring tool is separated from a working surface of a drill bit, at the moment, a core claw 4 can hold the core tightly under the action of lifting force, the first latch 41 (barb structure) of the core claw 4 is contracted under tension force, the core is more and more tightly pulled until the core is fractured, and core cutting is realized; (9) continuously lifting the drilling tool, and lifting the rock core out of the wellhead; (10) and taking out the core inner cylinder 7 filled with the core, and packaging the core for later use.

Any numerical value recited herein includes all values from the lower value to the upper value that are incremented by one unit, provided that there is a separation of at least two units between any lower value and any higher value. For example, if it is stated that the number of a component or a value of a process variable (e.g., temperature, pressure, time, etc.) is from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, it is intended that equivalents such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also expressly enumerated in this specification. For values less than 1, one unit is suitably considered to be 0.0001, 0.001, 0.01, 0.1. These are only examples of what is intended to be explicitly recited, and all possible combinations of numerical values between the lowest value and the highest value that are explicitly recited in the specification in a similar manner are to be considered.

Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. The use of "about" or "approximately" with a range applies to both endpoints of the range. Thus, "about 20 to about 30" is intended to cover "about 20 to about 30", including at least the endpoints specified.

All articles and references disclosed, including patent applications and publications, are hereby incorporated by reference for all purposes. The term "consisting essentially of …" describing a combination shall include the identified element, ingredient, component or step as well as other elements, ingredients, components or steps that do not materially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, or steps herein also contemplates embodiments that consist essentially of such elements, components, or steps. By using the term "may" herein, it is intended to indicate that any of the described attributes that "may" include are optional.

A plurality of elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step may be divided into separate plural elements, components, parts or steps. The disclosure of "a" or "an" to describe an element, ingredient, component or step is not intended to foreclose other elements, ingredients, components or steps.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego such subject matter, nor should the inventors be construed as having contemplated such subject matter as being part of the disclosed subject matter.

Claims

1. a flexible closed coring tool, comprising: the core drill bit mechanism and the flexible drill rod are connected in sequence; a core inner barrel penetrates through the flexible drill rod; the front end of the core inner cylinder is supported in the coring bit mechanism;

the flexible drill pipe comprises a first drill pipe joint, a second drill pipe joint and a plurality of drill pipe short sections which are connected end to end and are positioned between the first drill pipe joint and the second drill pipe joint; the flexible drill rod is connected with the coring bit mechanism through the first drill rod joint; the two adjacent drill pipe short sections can be bent by a preset angle; the inner wall of the core claw is provided with a first clamping tooth inclining backwards, and the outer wall of the sealing head is provided with a second clamping tooth matched with the first clamping tooth; the second latch inclines forwards; the core claw can be radially expanded and reset.

2. The flexible closed core tool according to claim 1, wherein: the cross section of the core claw is an open circular ring.

3. The flexible closed core tool according to claim 1, wherein: a fixing piece is also fixed at the rear end of the core inner cylinder; the fixing piece is used for keeping the position of the sealing head when the sealing head enters the inner core barrel.

4. The flexible closed core tool according to claim 3, wherein: the fixing piece comprises a permanent magnet block arranged at the rear end of the core inner cylinder; the closed head is made of a material which can be attracted by a magnet.

5. The flexible closed core tool according to claim 1, wherein: a first annular channel is arranged between the core inner cylinder and the flexible drill rod; the coring bit is provided with a fluid flow passage in communication with the first annular passage.

6. The flexible closed core tool according to claim 4, wherein: the rear end of the core inner barrel is also provided with a pressure balance mechanism, and the pressure balance mechanism is used for balancing the pressure intensity inside the core inner barrel; a water passing sleeve is sleeved outside the rear end of the core inner cylinder; and a water passing channel is arranged on the wall of the water passing sleeve.

7. The flexible closed core tool according to claim 6, wherein: the pressure balance mechanism comprises a load relief nut and an inner cylinder pressure balance piston; the fixing piece is arranged at the front end of the inner cylinder pressure balance piston; the unloading nut covers the rear end of the core inner cylinder; the front end of the inner cylinder pressure balance piston is positioned in the core inner cylinder and is in sealing fit with the wall of the core inner cylinder, and the rear end of the inner cylinder pressure balance piston penetrates through the load relief nut.

8. the flexible closed core tool according to any one of claims 1 to 7, wherein: the drill pipe sub comprises:

9. The flexible closed coring tool of claim 8, wherein the gear teeth are integrally formed with the ball head structure; the transmission teeth extend along an arc line or an envelope line from top to bottom; the track groove is an arc-shaped groove.

10. The flexible closed coring tool of claim 9, wherein the outer profile of the cross-section of the drive teeth is a partial arc; the diameter of the outer contour of the cross section of the transmission gear is increased from top to bottom and then reduced.

11. The flexible encapsulated coring tool of claim 10, wherein the maximum diameter location of the outer profile of the drive tooth cross-section is closer to the rear end of the drive tooth than to the front end of the drive tooth; the first sealing outer spherical surface and the second sealing outer spherical surface are positioned on the same sphere; the maximum diameter position and the sphere center of the sphere are positioned on the same cross section.

12. The flexible encapsulated coring tool of claim 11, wherein at least one of said first seal outer spherical surface and said first seal inner spherical surface, and/or at least one of said second seal outer spherical surface and said second seal inner spherical surface is provided with an annular lubrication groove; and high-temperature-resistant lubricating grease is filled in the lubricating oil groove.

13. The flexible closed core tool according to claim 8, wherein the gear sleeve mechanism comprises a gear sleeve, and an end cap; the gear sleeve is fixedly connected with the front end of the end cover and forms the movable space; the outer wall of the gear sleeve is provided with a first spherical surface structure; the rear end of the gear sleeve is connected with the end cover; the first sealing inner spherical surface and the track groove are arranged on the inner wall of the gear sleeve; the second sealing inner spherical surface is arranged at the front end of the end cover; the end cover is provided with the second connecting part; the rear end of the end cover is sleeved outside the front end of the spherical tooth mechanism and is provided with a second spherical structure matched with the first spherical structure.