Ultra-short radius drilling flexible power sub and use method thereof

Abstract

The present invention is a flexible power sub for ultra-short radius drilling and a method for using the same. The flexible power sub is provided with a transmission shaft, a turbine housing, rotor blades and stator blades. An upper liquid port and a lower liquid port are provided in the transmission shaft. The turbine housing is fixed to the outside of the shaft body of the transmission shaft; the rotor blades are fixed to the outer wall of the transmission shaft, and the stator blades are fixed to the inner wall of the turbine housing. The rotor blades fixed to the outer wall of the transmission shaft can rotate freely in the stator blades fixed to the inner wall of the turbine housing; a rod body connection joint and a ball connection joint are provided at both ends of the shaft body of the transmission shaft, respectively. The flexible power sub can be matched with drilling tools in ultra-short radius side-drilling horizontal well flexible drilling tools such as existing flexible subs, and can realize the free combination of flexible power subs and flexible subs, as well as between flexible power subs and flexible power subs, and has a significant use effect and can produce significant economic and social benefits.

Description

Technical Field

[0001] The invention relates to a power-assisted drilling device for a horizontal section of an ultra-short radius side-drilling horizontal well in the petroleum industry, in particular to an ultra-short radius drilling flexible power nipple and a use method thereof. Background Art

[0002] As most of my country's oilfield development enters the middle and late stages, oil extraction requires new technical means to achieve an increase in oil reservoir recovery at the lowest possible cost. Implementing side drilling on the basis of old wells can greatly save the initial exploration costs and drilling construction costs, and fully utilize the proven oil reserves. Practice has shown that side drilling can tap the potential of remaining oil in oil fields and improve the injection and production well network. It can especially play the above advantages for the local enrichment of remaining oil in the whole oil field and the loft oil in the fault block oil field. Horizontal wells can maximize the oil leakage area, improve the uniform utilization of the oil reservoir, and increase crude oil production and recovery. Therefore, side drilling horizontal wells have become an important technical means for domestic oil development under the current situation.

[0003] However, conventional sidetracking horizontal wells have the problem of large displacement before the target, resulting in a large amount of invalid footage, and the remaining oil near the wellbore of the old well cannot be effectively mobilized. Ultra-short radius sidetracking horizontal well technology can better solve the above problems. The curvature radius of the deflection section of the ultra-short radius sidetracking horizontal well is usually only within 6 m, which greatly shortens the displacement before the target, reduces the invalid footage, improves the accuracy of hitting the target, and improves the utilization of the remaining oil near the wellbore of the old well. In addition, the ultra-short radius sidetracking horizontal well technology is easy to operate, has a short construction period, and has low construction cost. Therefore, as an emerging domestic oil drilling technology, the ultra-short radius sidetracking horizontal well technology has been increasingly favored, and has a wide range of promotion and application prospects in my country's oil production field in the future, and will also create huge economic value.

[0004] There are two main types of ultra-short radius horizontal well technology, namely ultra-short radius hydraulic jet drilling and ultra-short radius side-drilling horizontal well with casing window; there are four specific technical means, namely open hole ultra-short radius hydraulic jet horizontal well technology, casing hole ultra-short radius hydraulic jet horizontal well technology, casing window ultra-short radius hydraulic jet horizontal well technology and casing window ultra-short radius side-drilling horizontal well technology. Since the wellbore trajectory formed by the first three technologies is difficult to control, the wellbore diameter is too small to implement sand control completion, and it is difficult to meet the actual needs of the oil development field, the domestic oil development field is currently mainly based on ultra-short radius side-drilling horizontal well technology with casing window, and the ultra-short radius side-drilling horizontal well technology involved in this patent application belongs to this type.

[0005] Chinese patent 2015104510629 discloses a specific implementation method of this type of ultra-short radius sidetracking horizontal well technology, which mainly includes the following steps: cleaning the original wellbore to make the wellbore smooth; testing the pressure to ensure that there is no leakage in the wellbore casing; using the drill pipe to lower the whipstock to the specified well depth, calibrating the depth with magnetic positioning, adjusting the normal azimuth of the whipstock slope with a gyroscope to make it consistent with the wellbore design azimuth, and dropping the ball and pressurizing to set the seal; using the drill pipe to lower the window drilling tool assembly, using the milling cone to mill the casing wall, milling out a window, and repairing the window, and then raising the window drilling tool assembly; using the drill pipe to lower the inclination flexible drilling tool assembly, a power drill can be used as a power source, and a guide pipe can be connected to the flexible drill pipe as an auxiliary, and the inclination drill bit drills out a curvature radius of 5 m of the inclination section wellbore; use the drill pipe to lower the flexible drilling tool assembly into the horizontal section, and drill to the bottom of the inclination section wellbore, and use the upper rotary table to provide power to drill the horizontal section. After drilling a certain distance, the horizontal section drilling is completed and the drilling tool is pulled out; use the drill pipe to lower the completion drilling tool, and use the drill pipe to reverse the flexible screen pipe carried by the completion drilling tool to place it in the drilled wellbore to achieve the screen pipe sand control completion.

[0006] This technology has realized the implementation of the casing window ultra-short radius side drilling horizontal well technology, but it faces certain technical bottlenecks. The main problem is that as the horizontal section drilling progresses, the length of the horizontal section flexible drill tool becomes longer and longer, the overall gravity becomes greater and greater, and the friction resistance of the well wall on the flexible drill tool increases significantly. On the one hand, the upper power cannot be effectively transmitted to the drill bit, which greatly reduces the rock breaking pressure and torque obtained by the drill bit and makes it impossible to continue drilling; on the other hand, since the flexible drill pipe is composed of multiple flexible short sections connected in series with ball head rods located between them, under the combined action of the lower friction and the upper pressure and torque, the flexible drill pipe is squeezed and twisted, and bends and deforms. This bending deformation makes the flexible drill pipe and the well wall in a "W" shape with multiple points of contact, which will cause the flexible drill pipe and the well wall to produce a carding effect, further increasing the resistance; the strength of the ball head rod connection structure is weaker than that of the integral drill pipe, so the further development of the bending deformation is easy to cause the damage of the flexible drill tool, greatly reducing the service life of the flexible drill tool. The above series of problems greatly limit the mechanical drilling speed and extension length of the horizontal section of ultra-short radius sidetracking horizontal wells, increase the construction cost and reduce the economic benefits of single wells.

[0007] In order to achieve greater economic benefits from the existing ultra-short radius sidetracking horizontal well technology in oilfield development, it is necessary to improve the mechanical drilling speed and extension length of the horizontal section of the ultra-short radius sidetracking horizontal well, and the key to achieving this goal is to solve the problems of wellbore friction and the resulting insufficient drill bit power and short service life of flexible drilling tools. Therefore, it is necessary to manufacture a horizontal section drilling tool that can be used in conjunction to solve the above problems. Summary of the invention

[0008] The purpose of the present invention is to provide an ultra-short radius drilling flexible power short section and a use method thereof, so as to realize the output of the near-drill-bit torque of the ultra-short radius flexible drilling tool, improve the drilling efficiency and extension length of the horizontal section of the ultra-short radius side-drilling horizontal well, and improve the development effect of the side-drilling horizontal well.

[0009] The technical solution of the present invention is achieved in this way:

[0010] An ultra-short radius drilling flexible power sub is provided with a transmission shaft, a turbine housing, rotor blades and stator blades, wherein:

[0011] An upper liquid outlet and a lower liquid outlet are provided in the transmission shaft;

[0012] The turbine housing is fixed outside the shaft body of the transmission shaft;

[0013] The rotor blades are fixed to the outer wall of the transmission shaft;

[0014] The stator blades are fixed to the inner wall of the turbine housing;

[0015] The rotor blades fixed to the outer wall of the transmission shaft can rotate freely in the stator blades fixed to the inner wall of the turbine housing;

[0016] The two ends of the shaft body of the transmission shaft are respectively provided with a rod body connecting joint and a ball connecting joint.

[0017] The upper inner wall of the rod body connecting joint is provided with an internal thread and can be threadedly connected to the rod body limit pin; the middle inner wall of the rod body connecting joint is provided with an internal spline and can be connected to the external spline of the ball head rod; the lower inner cavity of the rod body connecting joint is an upper liquid flow cavity composed of an inverted cone cavity and a cylindrical cavity, and the upper liquid flow cavity is connected with the upper liquid port; at least two upper liquid ports connected with the upper liquid flow cavity are provided and one group of upper liquid ports is evenly distributed along the circumference of the transmission shaft, and the upper liquid port is inclined outwardly in the transmission shaft at 25-35 degrees to the axis of the transmission shaft and is consistent with the direction of the upper inner wall of the turbine casing.

[0018] The rod body limiting pin is composed of two semicircular rings, the outer walls of the two semicircular rings are provided with external threads that can be connected to the inner wall of the upper part of the rod body connecting joint, and the inner circle formed by the two semicircular rings matches the rod body of the ball head rod.

[0019] The upper inner cavity of the ball connection joint is a lower liquid flow cavity composed of a cylindrical cavity and a positive cone cavity, and the lower liquid flow cavity is connected with a lower liquid outlet. There are at least two lower liquid outlets connected with the lower liquid flow cavity, and one group of lower liquid outlets is evenly distributed along the circumference of the transmission shaft. The lower liquid outlet is inclined inwardly at 25-35 degrees with the axis of the transmission shaft and is consistent with the direction of the lower inner wall of the turbine housing; the middle inner cavity of the ball connection joint is an upper arc cavity and a transmission tooth meshing groove is provided below the upper arc cavity; the lower inner cavity of the ball connection joint is provided with an internal thread and can be connected with a ball head limit pin.

[0020] The upper arc surface cavity in the middle part of the spherical connecting joint can be installed with the upper part of the ball head of the ball head rod, and the transmission tooth meshing groove below the upper arc surface cavity can be inserted with the transmission tooth in the ball head; the upper inner cavity of the ball head limit pin is the lower arc surface cavity, which can support the lower part of the ball head; the lower inner cavity of the ball head limit pin is a positive cone movable cavity.

[0021] The taper of the positive conical active cavity of the ball head limit pin is set between 20 degrees and 35 degrees; the height of the transmission tooth meshing groove in the ball head limit pin is greater than the height of the transmission tooth in the ball head; the minimum inner diameter of the ball head limit pin is smaller than the outer diameter of the ball head and larger than the outer diameter of the external spline in the ball head rod.

[0022] The shells at both ends of the turbine casing are conical and the inclination angles of the shells at both ends are the same as the inclination angles of the upper liquid outlet and the lower liquid outlet; the maximum outer diameters of the rod connecting joint and the ball connecting joint are both smaller than the outer diameter of the turbine casing; straightening bearings are installed between the shells at both ends of the turbine casing and the shaft bodies at both ends of the transmission shaft; the middle outer wall of the turbine casing is provided with an anti-slip strip and the maximum outer diameter is larger than the outer diameter of the flexible short section.

[0023] Stator blade bases are arranged at equal distances on the inner wall of the turbine housing. The stator blade bases are annular protrusions that protrude from the inner wall surface of the turbine housing and can be fixedly connected to the outer edges of the stator blades. The inner edges of the stator blades are fixedly connected to the stator blade crowns; the stator blade crowns are annular bodies and a gap is provided between the front end and the shaft body of the transmission shaft; at least three anti-slip strips are provided and are axially arranged on the middle outer wall of the turbine housing.

[0024] The transmission shaft is provided with a rotor blade base spaced apart from the stator blade crown on the outer wall of the shaft body between the upper liquid inlet and the lower liquid inlet. The rotor blade base is an annular protrusion protruding from the outer wall surface of the transmission shaft and capable of fixing the rotor blades. The inner edge of the rotor blade is fixedly connected to the rotor blade base and a gap is provided between the outer edge of the rotor blade and the inner wall of the turbine housing; the radial thickness of the stator blade crown is less than the radial height of the rotor blade base.

[0025] The rotor blades and the stator blades have the same blade profile structure and are arranged in opposite directions; a gap is provided between the rotor blades and the stator blades in the axial direction.

[0026] A method for using a flexible power sub for ultra-short radius drilling is as follows: the flexible power sub 1 can be connected in series with the flexible power sub or the flexible sub can be connected in series continuously or intermittently in a flexible drill rod close to a drill bit in a flexible power drilling tool for ultra-short radius drilling through a ball head rod.

[0027] Compared with the prior art, the present invention has the following remarkable effects:

[0028] ① The flexible power sub in the present invention can be matched with drilling tools in ultra-short radius side-drilling horizontal well flexible drilling tools such as existing flexible subs, and can realize the free combination of flexible power subs and flexible power subs, and the number of flexible power subs can be determined according to the actual needs of drilling and the connection order can be freely adjusted.

[0029] ②The external structure of the flexible power sub meets the requirements for running into the deflection section and horizontal section of an ultra-short radius sidetracking horizontal well. By combining with the flexible sub to form a power flexible drill pipe, it can be run into the horizontal section of an ultra-short radius sidetracking horizontal well.

[0030] ③ The power flexible drill pipe in the present invention can output torque directly near the drill bit during the drilling process of the horizontal section of the ultra-short radius side-drilling horizontal well under the condition of drilling fluid circulation, thereby compensating for the power loss caused by friction in the upper pipe string, and preventing the flexible power drill from bending, deforming and damaging, thereby increasing the service life of the flexible power drill. In general, it can greatly increase the power of the drill bit, improve the mechanical drilling speed and extension distance of the horizontal section of the ultra-short radius side-drilling horizontal well, and increase the single well production while reducing costs and improving efficiency.

[0031] ④ The outer diameter of the flexible power short section in the present invention is larger than the outer diameter of the flexible short section, which can support the rotating shaft assembly composed of the transmission shaft, ball head rod and flexible short section of the flexible power short section during the drilling process of the horizontal section of the ultra-short radius side drilling horizontal well, prevent the rotating shaft assembly from contacting the well wall, thereby greatly reducing the circumferential friction of the rotating shaft assembly and improving the power of the drill bit. This structure also increases the pressure on the unit support area, thereby improving the grip and improving the anti-slip performance of the turbine casing of the flexible power short section.

[0032] ⑤ The anti-skid strip can prevent the turbine housing from rotating in the opposite direction, ensuring good power output performance of the flexible power sub. At the same time, the anti-skid strip can support the turbine housing at a certain distance relative to the well wall, thereby generating an annular space gap as a flow channel for the upward return drilling fluid, thereby improving the circulation capacity of the drilling fluid.

[0033] ⑥The two ends of the turbine casing are tapered, which can have two beneficial effects: first, it is conducive to improving the flow performance of the drilling fluid in the process of entering the turbine blade group from the upper liquid port, reducing the hydraulic loss of the drilling fluid, and improving the utilization efficiency of the drilling fluid energy; second, it shortens the length of the middle cylindrical section of the flexible power short section, thereby reducing the contact area between the turbine casing as the supporting body and the well wall, increasing the pressure per unit area, thereby increasing the grip of the anti-slip strip and improving its anti-slip performance.

[0034] In summary, the present invention has significant use effects and can generate significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 It is a schematic diagram of the main structure of the ultra-short radius flexible power drilling tool of the present invention.

[0037] Figure 2 yes Figure 1 Schematic diagram of the structure of the medium-flexible power sub.

[0038] Figure 3 yes Figure 2 Schematic diagram of the structure of A-A.

[0039] Figure 4 yes Figure 1 Schematic diagram of the structure of the middle ball head.

[0040] Figure 5 yes Figure 4 Top view of the . DETAILED DESCRIPTION

[0041] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0042] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0044] See also Figures 1 to 5, an ultra-short radius drilling flexible power sub, comprising a transmission shaft 1.1, a turbine housing 1.2, a rotor blade 1.4 and a stator blade 1.3, wherein:

[0045] An upper liquid inlet 1.5 and a lower liquid inlet 1.12 are provided in the transmission shaft 1.1;

[0046] The turbine housing 1.2 is fixed outside the shaft body of the transmission shaft 1.1;

[0047] The rotor blades 1.4 are fixed to the outer wall of the transmission shaft 1.1;

[0048] The stator blades 1.3 are fixed to the inner wall of the turbine housing 1.2;

[0049] The rotor blades 1.4 fixed to the outer wall of the transmission shaft 1.1 can rotate freely in the stator blades 1.3 fixed to the inner wall of the turbine housing 1.2;

[0050] The two ends of the shaft body of the transmission shaft 1.1 are respectively provided with a rod connecting joint and a ball connecting joint.

[0051] The present invention can be connected to the flexible drilling tool of the ultra-short radius side-drilling horizontal well, and lowered into the deflection section and horizontal section of the ultra-short radius horizontal well. When the drilling fluid passes through the flexible power sub 1, the hydraulic energy of the liquid flow can be converted into the mechanical energy of the rotation of the transmission shaft 1.1, and the torque is output and transmitted to the drill bit 4. The flexible power sub 1 can be connected to the flexible drill pipe composed of the ball head rod 2 and the flexible sub 3 through the rod body connection joints and the ball body connection joints at both ends of the shaft body of the transmission shaft 1.1, and can achieve the process of drilling the horizontal section of the ultra-short radius side-drilling horizontal well. Under the condition of the circulation of drilling fluid, the torque can be directly output near the drill bit 4, thereby compensating for the power loss caused by the friction resistance of the upper pipe string, and can also prevent the damage caused by the bending deformation of the flexible power drilling tool, thereby improving the service life of the flexible power drilling tool. The near-drill-bit torque provided by the ultra-short-radius flexible power drill connected to the present invention can make up for the problem of insufficient torque transmission of the upper pipe string due to the friction resistance along the well wall, and can also, with the help of the near-drill-bit power, more easily break through the maximum static friction force, and convert the static friction between the drill tool and the well wall into dynamic friction. Since the dynamic friction force is less than the maximum static friction force, the axial and circumferential friction resistance is reduced, and the possibility of the flexible drill tool being stuck with the well wall is reduced, thereby improving the transmission efficiency of drilling pressure and torque, preventing the flexible drill tool from bending, deformation or even damage, thereby increasing the service life of the flexible drill tool.

[0052] Based on the above embodiment 1, the present invention also has the following embodiments:

[0053] The upper inner wall of the rod body connecting joint is provided with an internal thread and can be threadedly connected to the rod body limit pin 1.8; the middle inner wall of the rod body connecting joint is provided with an internal spline 1.7 and can be connected to the external spline 2.2 of the ball head rod 2; the lower inner cavity of the rod body connecting joint is an upper liquid flow cavity composed of an inverted cone cavity and a cylindrical cavity, and the upper liquid flow cavity is connected with the upper liquid port 1.5; the upper liquid port 1.5 connected with the upper liquid flow cavity is provided with at least two and one group of upper liquid ports 1.5 are evenly distributed along the circumference of the transmission shaft 1.1, and the upper liquid port 1.5 is inclined outwardly in the transmission shaft 1.1 at 25-35 degrees with the axis of the transmission shaft 1.1 and is consistent with the direction of the upper inner wall of the turbine casing 1.2.

[0054] The rod body stop pin 1.8 is composed of two semicircular rings, the outer walls of the two semicircular rings are provided with external threads that can be connected to the inner wall of the upper part of the rod body connection joint, and the inner circle formed by the two semicircular rings is consistent with the rod body 2.1 of the ball head rod 2. That is, the thickness of the inner wall of the rod body stop pin 1.8 protruding from the inner wall surface of the upper part of the rod body connection joint is consistent with the height of the external spline 2.2 protruding from the outer surface of the rod body 2.1. After the outer spline 2.2 at the lower part of the rod body 2.1 is inserted into the inner spline 1.7 of the rod body connection joint, the two semicircular rings of the rod body limit pin 1.8 wrap around the outer surface of the rod body 2.1 between the outer spline 2.2 and the ball head 2.3, and align the corresponding cross-sections of the two semicircular rings. At this time, the rod body limit pin 1.8 surrounds the outer surface of the rod body 2.1 as a whole as a circular ring, and then tightens the thread between the rod body limit pin 1.8 and the rod body connection joint. At this time, the rod body limit pin 1.8 is fixed just above the outer spline 2.2 and close to the upper surface of the outer spline 2.2, thereby limiting the axial displacement of the outer spline 2.2 and the entire ball head rod 2 integrated with it relative to the rod body connection joint of the transmission shaft 1.1. When the flexible power drill needs to be pulled outward during the drilling process or after the drilling is completed, it can prevent the rod body 2.1 from falling off relative to the transmission shaft 1.1 of the flexible power short section 1, ensuring that the entire string of flexible power drills is continuously lifted out.

[0055] The upper inner cavity of the ball connection joint is a lower liquid flow cavity composed of a cylindrical cavity and a positive cone cavity, and the lower liquid flow cavity is connected to the lower liquid outlet 1.12; at least two lower liquid outlets 1.12 connected to the lower liquid flow cavity are provided, and one group of lower liquid outlets 1.12 is evenly distributed along the circumference of the transmission shaft 1.1, and the lower liquid outlets 1.12 are inclined inwardly at 25-35 degrees to the axis of the transmission shaft 1.1 in the transmission shaft 1.1 and are consistent with the direction of the lower inner wall of the turbine housing 1.2; the middle inner cavity of the ball connection joint is an upper arc cavity and a transmission tooth meshing groove 1.9 is provided below the upper arc cavity; the lower inner cavity of the ball connection joint is provided with an internal thread and can be connected to the ball head limit pin 1.11. The upper liquid inlet 1.5 and the lower liquid inlet 1.12 are respectively located within the range covered by the turbine housing 1.2 at both ends of the shaft of the transmission shaft 1.1. The same group of liquid inlets are evenly arranged along the circumference of the transmission shaft 1.1. The direction of the liquid flow channel of the upper liquid inlet 1.5 and the lower liquid inlet 1.12 is scattered downward and upward from the axis. The number of openings of the upper liquid inlet 1.5 and the lower liquid inlet 1.12 is at least two, and the specific number can be determined according to the displacement requirement. The upper liquid inlet 1.5 can flow the liquid flow from the upper part from the front waterway through the upper liquid inlet 1.5 into the turbine chamber of the turbine housing 1.2, flow through the turbine blade group composed of the rotor blades 1.4 and the stator blades 1.3 and generate torque, and then merge into the subsequent waterway through the lower liquid inlet 1.12. The direction of the liquid flow channel of the upper liquid port 1.5 and the lower liquid port 1.12 is inclined at an angle of 25-35 degrees relative to the axial direction of the transmission shaft 1.1, which can enhance the flow diversion ability of the liquid flow in the waterway, avoid the liquid flow from the upper waterway into the turbine chamber. The angle is too large, and the liquid flow from the upper liquid port 1.5 is directly directed to the turbine blade group, reducing hydraulic losses. Similarly, the liquid flow after passing through the turbine blade group flows to the lower liquid port 1.12 at a small angle to enter the subsequent waterway, thereby reducing the hydraulic loss of the liquid flow. The direction of the liquid flow channel of the two groups of liquid ports is also consistent with the inner wall direction of the turbine housing 1.2, thereby reducing the hydraulic loss of the liquid flow on the inner wall of the turbine housing 1.2.

[0056] The upper arc surface cavity in the middle of the ball joint can be loaded with the upper part of the ball head 2.3 of the ball head rod 2, and the transmission tooth meshing groove 1.9 below the upper arc surface cavity can be inserted with the transmission tooth 2.4 in the ball head 2.3; the upper inner cavity of the ball head stop pin 1.11 is a lower arc surface cavity, which can support the lower part of the ball head 2.3; the lower inner cavity of the ball head stop pin 1.11 is a positive cone movable cavity. The spherical cavity formed by the upper arc surface cavity in the ball joint and the lower arc surface cavity in the ball head stop pin 1.11 and the positive cone movable cavity provide a movable space for the ball head rod 2.

[0057] The taper of the positive conical movable cavity of the ball stop pin 1.11 is set between 20 degrees and 35 degrees; the height of the transmission tooth meshing groove 1.9 in the ball stop pin 1.11 is greater than the height of the transmission tooth 2.4 in the ball head 2.3; the minimum inner diameter of the ball stop pin 1.11 is smaller than the outer diameter of the ball head 2.3 and larger than the outer diameter of the external spline 2.2 in the ball head rod 2. The spherical connecting joint connected to the ball stop pin 1.11 has a spherical cavity in which the ball head 2.3 of the ball head rod 2 can move, and the surface of the spherical cavity is provided with a transmission tooth meshing groove 1.9 along the circumferential direction that matches the transmission tooth 2.4 on the surface of the ball head 2.3. Figure 3 and Figure 5 It can be seen that in the circumferential direction, the outer contour of the transmission tooth 2.4 matches the transmission tooth meshing groove 1.9, so that the torque can be transmitted; while in the axial direction, Figure 1 As shown, since the height of the transmission tooth meshing groove 1.9 is greater than the height of the transmission tooth 2.4, the transmission tooth 2.4 has a certain upward and downward movable space in the transmission tooth meshing groove 1.9, so that the ball head 2.3 can be bent to a certain angle relative to the spherical connection joint. Similar to the way in which the rod body limit pin 1.8 limits the axial displacement of the rod body 2.1, after the thread between the ball head limit pin 1.11 and the spherical connection joint is tightened, since the ball head limit pin 1.11 is located directly below the ball head 2.3, and the minimum inner diameter of the ball head limit pin 1.11 is smaller than the outer diameter of the ball head 2.3, the axial displacement of the ball head 2.3 placed in the spherical cavity relative to the spherical connection joint can be limited, thereby preventing the ball head 2.3 from detaching from the spherical connection joint during the process of lifting the flexible power drilling tool. In general, the rod body limit pin 1.8 and the ball head limit pin 1.11 provide tensile strength for the flexible power drill, and can ensure the integrity and continuity of the entire string of flexible power drills when stretching the flexible power drill. The upper part of the inner wall of the ball head limit pin 1.11 is a lower arc cavity, which is consistent with the shape of the ball head 2.3, and together with the upper arc cavity in the spherical connection joint, forms a movable space for the ball head 2.3. As mentioned above, the minimum inner diameter of the ball head limit pin 1.11, that is, the circumferential diameter of the lower limit of the lower arc cavity is smaller than the spherical diameter of the ball head 2.3, thereby playing a role in limiting the axial displacement of the ball head 2.3, but the minimum inner diameter of the ball head limit pin 1.11 is larger than the outer diameter of the external spline 2.2 in the rod body 2.1, so that after the ball head 2.3 is placed in the spherical connection joint, the ball head limit pin 1.11 can pass through the external spline 2.2 and directly tighten with the thread corresponding to the spherical connection joint. At the same time, the inner diameter of the ball head limit pin 1.11 gradually increases from the lower limit of the lower arc cavity to become a positive cone movable cavity. Based on this, the ball head rod 2 can turn relative to the spherical connecting joint within a certain angle range, thereby ensuring the bending ability of the flexible power drilling tool.

[0058] The shells at both ends of the turbine casing 1.2 are conical and the inclination angles of the shells at both ends are the same as the inclination angles of the upper liquid port 1.5 and the lower liquid port 1.12; the maximum outer diameters of the rod connecting joint and the ball connecting joint are smaller than the outer diameter of the turbine casing 1.2, which is convenient for lowering; stabilizing bearings 1.6 are installed between the shells at both ends of the turbine casing 1.2 and the shaft bodies at both ends of the transmission shaft 1.1; the middle outer wall of the turbine casing 1.2 is provided with an anti-slip strip 1.10 and the maximum outer diameter is larger than the outer diameter of the flexible short section 3.

[0059] Stator blade bases are arranged at equal distances on the inner wall of the turbine casing 1.2. The stator blade bases are annular protrusions that protrude from the inner wall surface of the turbine casing 1.2 and can be fixedly connected to the outer edges of the stator blades 1.3. The inner edges of the stator blades 1.3 are fixedly connected to the stator blade crowns; the stator blade crowns are annular bodies and a gap is provided between the front end and the shaft body of the transmission shaft 1.1; the anti-slip strips 1.10 are provided with at least three strips and are axially arranged on the middle outer wall of the turbine casing 1.2. The outer wall surface of the turbine casing 1.2 is provided with anti-slip strips 1.10 and are evenly arranged along the circumference of the turbine casing 1.2 and the fixed direction is consistent with the axial direction of the transmission shaft 1.1, which can provide circumferential resistance for the turbine casing 1.2, and prevent the turbine casing 1.2 from rotating in the opposite direction due to the reverse effect of the liquid flow on the stator blades 1.3, ensuring that the flexible power short section 1 has good power output performance, and can also support the turbine casing 1.2 at a certain distance relative to the well wall, thereby creating a larger annular space gap for the drilling fluid flow channel and improving the circulation capacity of the drilling fluid. The turbine casing 1.2 is tapered at both ends, and the inner wall of its turbine chamber has an inclination angle consistent with the setting direction of the upper liquid port 1.5 and the lower liquid port 1.12, which is beneficial to improving the flow guidance performance of the liquid flow from the upper liquid port 1.5 into the turbine blade group and from the turbine blade group into the lower liquid port 1.12, reducing the hydraulic loss of the liquid flow, making full use of the liquid flow energy, and shortening the length of the middle cylindrical section of the turbine casing 1.2, thereby reducing the contact area between the turbine casing 1.2 as the supporting body and the well wall, increasing the pressure per unit area, thereby increasing the grip of the anti-slip strip 1.10 and improving its anti-slip performance.

[0060] The outer diameter of the turbine casing 1.2 is larger than the flexible short section 3, thereby supporting the rotating shaft assembly composed of the transmission shaft 1.1, the ball head rod 2 and the flexible short section 3, preventing the rotating shaft assembly from contacting the well wall, thereby greatly reducing friction resistance. This supporting structure can also increase the pressure of the turbine casing 1.2 on the unit area of ​​the bottom well wall, improve the grip of the anti-slip strip 1.10, and provide greater circumferential friction resistance for the turbine casing 1.2.

[0061] The transmission shaft 1.1 is provided with a rotor blade base spaced apart from the stator blade crown on the outer wall of the shaft body between the upper liquid port 1.5 and the lower liquid port 1.12. The rotor blade base is an annular protrusion protruding from the outer wall surface of the transmission shaft 1.1 and capable of fixing the rotor blade 1.4. The inner edge of the rotor blade 1.4 is fixedly connected to the rotor blade base and a gap is provided between the outer edge of the rotor blade 1.4 and the inner wall of the turbine housing 1.2; the radial thickness of the stator blade crown is smaller than the radial height of the rotor blade base, thereby playing a role in straightening and thrusting the shaft body of the transmission shaft 1.1.

[0062] The rotor blades 1.4 and the stator blades 1.3 have the same blade profile structure and are arranged in opposite directions; a gap is provided between the rotor blades 1.4 and the stator blades 1.3 in the axial direction, so that the rotor blades 1.4 and the stator blades 1.3 can rotate freely.

[0063] Based on this, when the liquid flows through the rotor blades 1.4, the pressure energy and kinetic energy of the liquid flow are converted into mechanical energy for the rotation of the transmission shaft 1.1, and its flow direction changes at the same time. When the liquid flows through the stator blades 1.3, since the layout direction of the stator blades 1.3 is opposite to that of the rotor blades 1.4, it plays a guiding role on the liquid flow, so that its flow direction is restored to the direction when it enters the previous rotor blades 1.4, so that it can act on the rotor blades 1.4 again. By analogy, on each level of rotor blades 1.4, the pressure energy and kinetic energy of the liquid flow can be converted into mechanical energy for the rotation of the transmission shaft 1.1, thereby greatly improving the output torque of the flexible power short section 1. The blade structure of the rotor blades 1.4 and the stator blades 1.3 can be designed in any specific way under the premise of meeting the expected function. There is a certain distance between the rotor blades 1.4 and the stator blades 1.3 in the axial direction, so that while the drilling fluid can pass smoothly, there is no jamming between the turbine blade group composed of the rotor blades 1.4 and the stator blades 1.3. This is achieved by adjusting the axial height of the rotor blade base, stator blade crown, and the height of the rotor blade 1.4 and stator blade 1.3, that is, the axial height of the rotor blade 1.4 and the stator blade 1.3 is required to be smaller than the axial height of the rotor blade base and the stator blade crown. The axial distance between the rotor blade 1.4 and the stator blade 1.3 will also affect the power output performance of the turbine blade group. The axial distance between the rotor blade 1.4 and the stator blade 1.3 is designed in combination with the turbodrill design theory to optimize the comprehensive performance of the turbine blade group.

[0064] A method for using a flexible power sub for ultra-short radius drilling, which is: the flexible power sub 1 can be connected in series with the flexible power sub 1 or the flexible sub 3 through the ball head rod 2 in a flexible drill pipe close to the drill bit 4 in the ultra-short radius drilling flexible power drill tool continuously or intermittently. The existing flexible drill pipe for ultra-short radius side drilling horizontal wells is composed of multiple sections of flexible subs 3 connected in series through the ball head rod 2, and the sections of flexible subs 3 are connected end to end through the ball head rod 2. Among them, the ball head rod 2 is provided with a center hole 2.5, and the surface of the ball head 2.3 is circumferentially distributed with transmission teeth 2.4, which match the transmission tooth meshing grooves in the spherical cavity at the lower end of the flexible sub 3, and can realize the transmission of torque while deflecting a certain angle, forming a ball tooth universal shaft mechanism; the lower end of the rod body 2.1 of the ball head rod 2 has an external spline 2.2, which matches the internal spline at the upper end of the flexible sub 3 to form a spline mechanism for transmitting torque. The inner wall of the rod body connecting joint in the flexible power short section 1 has an inner spline 1.7 that matches the outer spline 2.2 on the lower end surface of the rod body 2.1 of the ball head rod 2, and can be plugged into each other to transmit torque. The method of using the present invention can be:

[0065] 1. The flexible power sub 1 and the flexible power sub 1 are connected in series continuously or intermittently in the flexible drill rod through the ball head rod 2 to form a power flexible drill rod;

[0066] 2. It is also possible that the flexible power sub 1 and the flexible sub 3 are connected in series continuously or intermittently in the flexible drill rod through the ball head rod 2 to form a power flexible drill rod;

[0067] 3. It is also possible that the flexible power subsection 1 and the flexible subsection 3 are connected in series through the ball head rod 2 in the flexible drill pipe close to the drill bit 4 in the ultra-short radius drilling flexible power drill; the flexible power subsection 1 and the flexible subsection 3 are connected in series through the ball head rod 2 in an interval manner, which can be a manner in which more than two flexible subsections 3 connected in series through the ball head rod 2 and one flexible power subsection 1 are connected in series, or a manner in which one flexible subsection 3 connected in series through the ball head rod 2 and more than two flexible power subsections 1 connected in series through the ball head rod 2 are connected in series, and the flexible power subsection 1 and the flexible subsection 3 are mixedly connected to form a power flexible drill pipe.

[0068] The ultra-short radius drilling flexible power drilling tool is also provided with a drill bit 4, a variable buckle joint 6 connected to the upper end of the flexible drill rod, and a drill rod joint 5.

[0069] The embodiments described above are only typical embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and enlightenment of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. An ultra-short radius drilling flexible power sub, characterized in that: A transmission shaft (1.1), a turbine housing (1.2), rotor blades (1.4) and stator blades (1.3) are provided, wherein: an upper liquid inlet (1.5) and a lower liquid inlet (1.12) are provided in the transmission shaft (1.1); the turbine housing (1.2) is fixed to the outside of the shaft body of the transmission shaft (1.1); the rotor blades (1.4) are fixed to the outer wall of the transmission shaft (1.1); the stator blades (1.3) are fixed to the inner wall of the turbine housing (1.2); the rotor blades (1.4) fixed to the outer wall of the transmission shaft (1.1) can be fixed to the inner wall of the turbine housing (1.2); The stator blades (1.3) in the inner wall of the turbine housing (1.2) rotate freely; a rod body connection joint and a ball body connection joint are respectively provided at both ends of the shaft body of the transmission shaft (1.1); the upper inner wall of the rod body connection joint is provided with an internal thread and can be threadedly connected to the rod body limit pin (1.8); the middle inner wall of the rod body connection joint is provided with an internal spline (1.7) and can be connected to the external spline (2.2) of the ball head rod (2); the lower inner cavity of the rod body connection joint is an upper liquid flow cavity composed of an inverted cone cavity and a cylindrical cavity, and the upper liquid flow cavity is connected to the upper liquid port (1.5).

2. The ultra-short radius drilling flexible power sub as claimed in claim 1, characterized in that: At least two upper liquid ports (1.5) are provided and are evenly distributed along the circumference of the transmission shaft (1.1); the upper liquid ports (1.5) are tilted outwardly in the transmission shaft (1.1) at an angle of 25-35 degrees to the axis of the transmission shaft (1.1) and are aligned with the direction of the upper inner wall of the turbine housing (1.2).

3. The ultra-short radius drilling flexible power sub as claimed in claim 2, characterized in that: The rod body limiting pin (1.8) is composed of two semicircular rings matched together, the outer walls of the two semicircular rings are provided with external threads that can be connected to the inner wall of the upper part of the rod body connecting joint, and the inner circle formed by the two semicircular rings is consistent with the rod body (2.1) of the ball head rod (2).

4. The ultra-short radius drilling flexible power sub as claimed in claim 1, characterized in that: The upper inner cavity of the ball connection joint is a lower liquid flow cavity composed of a cylindrical cavity and a positive cone cavity. The lower liquid flow cavity is connected to a lower liquid outlet (1.12). At least two lower liquid outlets (1.12) are provided and are evenly distributed along the circumference of the transmission shaft (1.1). The lower liquid outlets (1.12) are inclined inwardly in the transmission shaft (1.1) at an angle of 25-35 degrees to the axis of the transmission shaft (1.1) and are consistent with the direction of the lower inner wall of the turbine housing (1.2); the middle inner cavity of the ball connection joint is an upper arc cavity and a transmission tooth meshing groove (1.9) is provided below the upper arc cavity; the lower inner cavity of the ball connection joint is provided with an internal thread and can be connected to the ball head limit pin (1.11).

5. The ultra-short radius drilling flexible power sub as claimed in claim 4, characterized in that: The upper arc surface cavity in the middle of the spherical connecting joint can accommodate the upper part of the ball head (2.3) of the ball head rod (2), and the transmission tooth meshing groove (1.9) below the upper arc surface cavity can be inserted with the transmission tooth (2.4) in the ball head (2.3); the upper inner cavity of the ball head stop pin (1.11) is a lower arc surface cavity, and the lower arc surface cavity can support the lower part of the ball head (2.3); the lower inner cavity of the ball head stop pin (1.11) is a positive conical movable cavity.

6. The ultra-short radius drilling flexible power sub as claimed in claim 5, characterized in that: The taper of the positive conical active cavity of the ball head stop pin (1.11) is set between 20 degrees and 35 degrees; the height of the transmission tooth meshing groove (1.9) in the ball head stop pin (1.11) is greater than the height of the transmission tooth (2.4) in the ball head (2.3); and the minimum inner diameter of the ball head stop pin (1.11) is smaller than the outer diameter of the ball head (2.3) and larger than the outer diameter of the outer spline (2.2) in the ball head rod (2).

7. An ultra-short radius drilling flexible power sub as claimed in claim 1, 2 or 4, characterized in that: The shells at both ends of the turbine housing (1.2) are conical and the inclination angles of the shells at both ends are the same as the inclination angles of the upper liquid port (1.5) and the lower liquid port (1.12); the maximum outer diameters of the rod body connection joint and the ball connection joint are both smaller than the outer diameter of the turbine housing (1.2); stabilizing bearings (1.6) are installed between the shells at both ends of the turbine housing (1.2) and the shaft bodies at both ends of the transmission shaft (1.1); and the middle outer wall of the turbine housing (1.2) is provided with an anti-slip strip (1.10) and the maximum outer diameter is larger than the outer diameter of the flexible short section (3).

8. The ultra-short radius drilling flexible power sub as claimed in claim 7, characterized in that The inner wall of the turbine housing (1.2) is provided with stator blade bases at equal distances, the stator blade bases being annular protrusions protruding from the inner wall surface of the turbine housing (1.2) and capable of being fixedly connected to the outer edges of the stator blades (1.3), the inner edges of the stator blades (1.3) being fixedly connected to the stator blade crowns; the stator blade crowns are annular bodies and a gap is provided between the front end and the shaft body of the transmission shaft (1.1); the anti-slip strips (1.10) are provided with at least three strips and are axially arranged on the middle outer wall of the turbine housing (1.2).

9. The ultra-short radius drilling flexible power sub as claimed in claim 8, characterized in that: The outer wall of the shaft body of the transmission shaft (1.1) between the upper liquid inlet (1.5) and the lower liquid inlet (1.12) is provided with a rotor blade base spaced apart from the stator blade crown; the rotor blade base is an annular protrusion protruding from the outer wall surface of the transmission shaft (1.1) and capable of fixing the rotor blade (1.4); the inner edge of the rotor blade (1.4) is fixedly connected to the rotor blade base, and a gap is provided between the outer edge of the rotor blade (1.4) and the inner wall of the turbine housing (1.2); the radial thickness of the stator blade crown is less than the radial height of the rotor blade base.

10. The ultra-short radius drilling flexible power sub as claimed in claim 9, characterized in that: The rotor blades (1.4) and the stator blades (1.3) have the same blade profile structure and the blade profile structures are arranged in opposite directions; and a gap is provided between the rotor blades (1.4) and the stator blades (1.3) in the axial direction.

11. A method for using the ultra-short radius drilling flexible power sub as claimed in claim 10, characterized in that: The flexible power sub (1) can be connected in series with the flexible power sub (1) or the flexible sub (3) via a ball head rod (2) in a flexible drill rod close to a drill bit (4) in an ultra-short radius drilling flexible power drilling tool, either continuously or intermittently.

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