Downhole resistivity instrument and forming method thereof

Abstract

The invention discloses an underground resistivity instrument and a forming method of the underground resistivity instrument, the underground resistivity instrument comprises a drill collar body, and a step groove is formed in the peripheral wall of the drill collar body; the antenna welding ring and the drill collar body jointly define an antenna containing cavity; wherein the step groove is provided with a first outer inclined plane and a second outer inclined plane, the antenna welding ring is provided with a first inner inclined plane and a second inner inclined plane, the first inner inclined plane and the first outer inclined plane are opposite and jointed, and the second inner inclined plane and the second outer inclined plane are opposite and define a filler welding groove. According to the underground resistivity instrument, the antenna can be installed and protected, the first outer inclined face and the first inner inclined face are connected with the second outer inclined face and the second inner inclined face in different welding modes, the connection strength between the drill collar body and the antenna welding ring can be improved, the welding stress can be released, and the reliability of the drill collar body is improved. The possibility of generating cracks at the weld joint is reduced, and the connection reliability between the drill collar body and the antenna welding ring is improved.

Description

Technical Field

[0001] The invention relates to the technical field of resistivity measurement, and in particular to a downhole resistivity instrument and a forming method suitable for the downhole resistivity instrument. Background Art

[0002] In the process of oil and gas development, a drilling electromagnetic wave resistivity instrument is used, which is mainly used to determine the resistivity of underground rock formations, so as to judge the oil, gas and water layers through the resistivity of underground rock formations. Among them, the antenna is a key component for transmitting and receiving electromagnetic wave signals, and it needs to be protected in harsh underground working conditions.

[0003] At present, there are two structures for the installation of resistivity antennas: one is a split outer cover structure, which is mainly connected by screws, but the connection strength of the screw connection is limited. In the case of long-term strong vibration underground, there is a risk of the screws loosening; the other is an integrated welded structure, but the filler is fully welded between the welding ring and the resistivity drill collar body, and the welding stress cannot be released. In the case of high-intensity vibration underground, there is a phenomenon of internal welding cracks, resulting in poor firmness. It is easy to be damaged during the subsequent strong vibration process, and there is room for improvement. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a downhole resistivity instrument, which can install and protect the antenna, improve the reliability and service life of the antenna, and can improve the connection strength between the drill collar body and the antenna welding ring, reduce the possibility of cracks at the weld, and improve the connection reliability between the drill collar body and the antenna welding ring.

[0005] According to an embodiment of the present invention, a downhole resistivity instrument includes: a drill collar body, the outer peripheral wall of the drill collar body is formed with a step groove extending in the circumferential direction; an antenna welding ring, the antenna welding ring is installed in the step groove and defines an antenna accommodating cavity together with the drill collar body; wherein the step groove has a first outer bevel and a second outer bevel relatively distributed in the axial direction, and the antenna welding ring has a first inner bevel and a second inner bevel relatively distributed in the axial direction, the first inner bevel is opposite to and engaged with the first outer bevel, and the second inner bevel is opposite to the second outer bevel and defines a filler welding groove.

[0006] According to the downhole resistivity instrument of an embodiment of the present invention, the antenna can be installed and protected by providing a drill collar body and an antenna welding ring, which can improve the reliability and service life of the antenna. The first outer bevel and the first inner bevel are connected with the second outer bevel and the second inner bevel by different welding methods, which can improve the connection strength between the drill collar body and the antenna welding ring, release the welding stress, reduce the possibility of cracks in the weld, and improve the connection reliability between the drill collar body and the antenna welding ring.

[0007] According to some embodiments of the downhole resistivity instrument of the present invention, the first inner slope is arranged in parallel with the first outer slope; and / or an angle is formed between the second inner slope and the second outer slope, and the width of the filler welding groove is constructed to gradually increase from the inside to the outside.

[0008] According to some embodiments of the downhole resistivity instrument of the present invention, the radial inclination angle of the first outer bevel relative to the drill shank body is A1, the radial inclination angle of the first inner bevel relative to the antenna welding ring is A2, and the following conditions are satisfied: 4°≤A1≤6°, 4°≤A2≤6°; and / or, the radial inclination angle of the second outer bevel relative to the drill shank body is B1, the radial inclination angle of the second inner bevel relative to the antenna welding ring is B2, the inclination directions of the second inner bevel are opposite to those of the second outer bevel, and the following conditions are satisfied: 25°≤B1≤35°, 25°≤B2≤35°.

[0009] According to some embodiments of the present invention, the downhole resistivity tool satisfies: A1=A2; and / or, B1=B2.

[0010] According to some embodiments of the downhole resistivity instrument of the present invention, the outer peripheral wall of the antenna welding ring is provided with a receiving slot, the receiving slot is open toward the step groove, and the inner wall of the receiving slot and the inner wall of the step groove jointly define the antenna receiving cavity.

[0011] According to some embodiments of the downhole resistivity instrument of the present invention, a first outer arc surface is provided in the step groove between the first outer bevel and the second outer bevel, and the antenna welding ring also has a first inner arc surface between the first inner bevel and the accommodating notch and between the second inner bevel and the accommodating notch, and the first outer arc surface is clearance-matched with the first inner arc surface.

[0012] According to some embodiments of the downhole resistivity instrument of the present invention, the gap width between the first outer arc surface and the first inner arc surface is L, and satisfies: 0.4mm≤L≤0.6mm.

[0013] According to some embodiments of the downhole resistivity instrument of the present invention, a second outer arc surface is provided in the step groove between the first outer bevel and / or the second outer bevel and the accommodating notch, and the antenna welding ring is further provided with a second inner arc surface between the first inner bevel and / or the second inner bevel and the accommodating notch, and the second outer arc surface is in contact with the second inner arc surface.

[0014] According to some embodiments of the downhole resistivity instrument of the present invention, the antenna welding ring includes at least two sub-welding segments, and the at least two sub-welding segments are spliced ​​in sequence along the circumference of the antenna welding ring.

[0015] According to some embodiments of the downhole resistivity instrument of the present invention, the drill collar body is further provided with an electromagnetic wave releasing slot extending along the axial direction, and the electromagnetic wave releasing slot passes through the step groove and is communicated with the antenna accommodating cavity.

[0016] According to some embodiments of the downhole resistivity instrument of the present invention, the first inner bevel and the first outer bevel are fixed by fusion welding; the second inner bevel and the second outer bevel are fixed by full filler welding.

[0017] The invention also provides a forming method of a downhole resistivity instrument.

[0018] According to the molding method of the downhole resistivity instrument of the present invention, the molding method is applicable to the downhole resistivity instrument described in any one of the above-mentioned embodiments, and the molding method includes: molding a step groove on the drill collar body; installing the antenna welding ring in the step groove, and making the first inner bevel opposite to the first outer bevel, and the second inner bevel opposite to the second outer bevel and defining a filler welding groove; first welding and fixing the second inner bevel and the second outer bevel; and then welding and fixing the first inner bevel and the first outer bevel.

[0019] According to the forming method of the downhole resistivity instrument of the present invention, the forming method comprises: firstly welding and fixing the second inner bevel and the second outer bevel by full welding of filler; and then welding and fixing the first inner bevel and the first outer bevel by fusion welding.

[0020] The forming method of the downhole resistivity instrument has the same advantages as the above-mentioned downhole resistivity instrument over the prior art, and will not be described in detail here.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 Schematic diagram of the structure of a downhole resistivity instrument according to an embodiment of the present invention Figure 1 ;

[0024] Figure 2 is a structural schematic diagram of a drill collar body according to an embodiment of the present invention;

[0025] Figure 3 yes Figure 2 A partial enlarged view of the middle A;

[0026] Figure 4 is a schematic structural diagram of an antenna welding ring according to an embodiment of the present invention;

[0027] Figure 5 is a schematic structural diagram of a sub-welding section according to an embodiment of the present invention;

[0028] Figure 6 is a schematic diagram of assembling a drill collar body and an antenna welding ring according to an embodiment of the present invention;

[0029] Figure 7 yes Figure 6 Schematic diagram of the structure at B in the middle;

[0030] Figure 8 Schematic diagram of the structure of a downhole resistivity instrument according to an embodiment of the present invention Figure 2 ;

[0031] Fig. 9 is a cross-sectional view of a downhole resistivity instrument according to an embodiment of the present invention;

[0032] Fig.10 is a flow chart of a method for forming a downhole resistivity instrument according to the present invention.

[0033] Reference numerals:

[0034] Downhole resistivity instrument 100,

[0035] Drill collar body 1, step groove 11, first outer bevel 12, second outer bevel 13, first outer arc surface 14, second outer arc surface 15, electromagnetic wave release notch 16,

[0036] Antenna welding ring 2, antenna accommodating cavity 21, first inner inclined surface 22, second inner inclined surface 23, filler welding groove 24, accommodating notch 25, first inner arc surface 26, second inner arc surface 27, sub-welding section 28. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying 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 a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] Reference below Figure 1-Figure 10 A downhole resistivity instrument 100 according to an embodiment of the present invention is described. By providing a drill collar body 1 and an antenna welding ring 2, the antenna can be installed and protected, which can improve the reliability and service life of the antenna. The first outer bevel 12 and the first inner bevel 22 are connected with the second outer bevel 13 and the second inner bevel 23 by different welding methods, which can improve the connection strength between the drill collar body 1 and the antenna welding ring 2, release the welding stress, reduce the possibility of cracks in the weld, and improve the connection reliability between the drill collar body 1 and the antenna welding ring 2.

[0041] like Figure 1 As shown, a downhole resistivity instrument 100 according to an embodiment of the present invention includes: a drill collar body 1 and an antenna welding ring 2.

[0042] The outer wall of the drill collar body 1 is formed with a step groove 11 extending in the circumferential direction; the antenna welding ring 2 is installed in the step groove 11 and together with the drill collar body 1 defines an antenna accommodating cavity 21; wherein, the step groove 11 has a first outer bevel 12 and a second outer bevel 13 relatively distributed in the axial direction, and the antenna welding ring 2 has a first inner bevel 22 and a second inner bevel 23 relatively distributed in the axial direction, the first inner bevel 22 is opposite to and engaged with the first outer bevel 12, and the second inner bevel 23 is opposite to the second outer bevel 13 and defines a filler welding groove 24.

[0043] Specifically, the downhole resistivity instrument 100 is used to determine the resistivity of underground rock formations. The antenna is installed in the downhole resistivity instrument 100 as a key component for receiving and transmitting signals. The downhole resistivity instrument 100 includes a drill collar body 1 and an antenna welding ring 2, wherein the drill collar body 1 is used to provide an installation position for the antenna, and the antenna welding ring 2 is used to fix the antenna. The drill collar body 1 can be connected to the antenna welding ring 2 so that the drill collar body 1 and the antenna welding ring 2 can jointly define an antenna accommodating cavity 21, so that the antenna can be inserted into the antenna accommodating cavity 21 to achieve the installation of the antenna, and the antenna can be fixed and protected by the drill collar body 1 and the antenna welding ring 2 to improve the reliability and service life of the antenna.

[0044] At the same time, if Figure 2 , Figure 4 and Figure 6 As shown, the drill collar body 1 is constructed into a cylindrical shape, the antenna welding ring 2 is constructed into an annular shape, and the drill collar body 1 is formed with a step groove 11, the step groove 11 is used to accommodate the antenna welding ring 2, and the step groove 11 is constructed to extend along the circumference of the drill collar body 1, that is, the step groove 11 can also be constructed into an annular shape, so that the antenna welding ring 2 can be installed in the step groove 11 to achieve the connection between the drill collar body 1 and the antenna welding ring 2, and the step groove 11 is formed on the outer peripheral wall of the drill collar body 1 to open the step groove 11 toward the outside of the drill collar body 1, so as to facilitate the antenna welding ring 2 to be set in the step groove 11 from the outside of the drill collar body 1, which can reduce the difficulty of installation.

[0045] In addition, the step groove 11 has a first outer bevel 12 and a second outer bevel 13, and the antenna welding ring 2 has a first inner bevel 22 and a second inner bevel 23. The first outer bevel 12 is engaged with the first inner bevel 22, and the first outer bevel 12 and the first inner bevel 22 can be connected by a fusion welding process to form a stress release surface, release the welding stress, reduce the possibility of cracks at the weld between the drill collar body 1 and the antenna welding ring 2, and improve the connection reliability between the drill collar body 1 and the antenna welding ring 2. The second outer bevel 13 and the second inner bevel 23 define a filler welding groove 24, and the filler welding groove 24 is used to accommodate solder, so that the second outer bevel 13 and the second inner bevel 23 can be connected by full filler welding to improve the connection strength between the drill collar body 1 and the antenna welding ring 2.

[0046] Therefore, the first outer bevel 12 and the first inner bevel 22 can be connected with the second outer bevel 13 and the second inner bevel 23 by different welding methods, which can improve the connection strength between the drill shank body 1 and the antenna welding ring 2, and release the welding stress to reduce the possibility of cracks at the weld between the drill shank body 1 and the antenna welding ring 2, thereby improving the connection reliability between the two. Among them, the filler full welding method can be a stacking argon arc welding process.

[0047] Furthermore, the first outer bevel 12 and the second outer bevel 13 are relatively distributed axially, and the first inner bevel 22 and the second inner bevel 23 are relatively distributed axially, so that the first outer bevel 12 and the second outer bevel 13 correspond to the first inner bevel 22 and the second inner bevel 23 respectively, and the drill collar body 1 and the antenna welding ring 2 can be connected at two positions in the length direction of the drill collar body 1 at the same time to improve the connection reliability between the two. Moreover, the first outer bevel 12 and the second outer bevel 13 are relatively distributed, so that the first outer bevel 12 and the second outer bevel 13 are distributed separately, and the first inner bevel 22 and the second inner bevel 23 are relatively distributed, so that the first inner bevel 22 and the second inner bevel 23 are distributed separately to avoid interference between the connection between the first outer bevel 12 and the first inner bevel 22 and the connection between the second outer bevel 13 and the second inner bevel 23, resulting in the drill collar body 1 and the antenna welding ring 2 being unable to be connected or the connection strength being reduced.

[0048] According to the downhole resistivity instrument 100 of the embodiment of the present invention, the antenna can be installed and protected by providing the drill collar body 1 and the antenna welding ring 2, which can improve the reliability and service life of the antenna. The first outer bevel 12 and the first inner bevel 22 are connected with the second outer bevel 13 and the second inner bevel 23 by different welding methods, which can improve the connection strength between the drill collar body 1 and the antenna welding ring 2, release the welding stress, reduce the possibility of cracks in the weld, and improve the connection reliability between the drill collar body 1 and the antenna welding ring 2.

[0049] In some embodiments, the first inner bevel 22 is arranged in parallel with the first outer bevel 12; and / or, an angle is formed between the second inner bevel 23 and the second outer bevel 13, and the width of the filler welding groove 24 is configured to gradually increase from the inside to the outside.

[0050] Specifically, the first inner bevel 22 and the first outer bevel 12 can be welded together. The first inner bevel 22 and the first outer bevel 12 can be arranged in parallel so that the distance between the first inner bevel 22 and the first outer bevel 12 can be equal everywhere, so as to ensure that the drill collar body 1 and the antenna welding ring 2 can be evenly heated during the welding process, so as to reduce welding defects caused by uneven heat distribution, such as deformation or incomplete fusion, and can reduce uneven thermal expansion during welding, thereby reducing welding stress, that is, releasing welding stress to reduce the possibility of cracks in the weld.

[0051] Furthermore, the second inner bevel 23 and the second outer bevel 13 can be welded together, and an angle is formed between the second inner bevel 23 and the second outer bevel 13, that is, there is a certain gap between the second inner bevel 23 and the second outer bevel 13 to form a filler welding groove 24, and the width of the filler welding groove 24 gradually increases from the inside to the outside, so that the width of the filler welding groove 24 on the outside can be larger, so as to facilitate the addition of solder into the filler welding groove 24, and the flow path of the solder can be optimized so that it can be more evenly distributed and filled in the filler welding groove 24, thereby improving the connection strength and connection reliability between the drill collar body 1 and the antenna welding ring 2.

[0052] In some embodiments, the radial inclination angle of the first outer bevel 12 relative to the drill shank body 1 is A1, the radial inclination angle of the first inner bevel 22 relative to the antenna welding ring 2 is A2, and the following conditions are satisfied: 4°≤A1≤6°, 4°≤A2≤6°; and / or, the radial inclination angle of the second outer bevel 13 relative to the drill shank body 1 is B1, the radial inclination angle of the second inner bevel 23 relative to the antenna welding ring 2 is B2, the inclination directions of the second inner bevel 23 and the second outer bevel 13 are opposite, and the following conditions are satisfied: 25°≤B1≤35°, 25°≤B2≤35°.

[0053] Specifically, the antenna welding ring 2 is installed in the step groove 11 on the outer peripheral wall of the drill collar body 1, that is, the radial direction of the drill collar body 1 is parallel to the radial direction of the antenna welding ring 2. Figure 3As shown, the first outer bevel 12 is inclined relative to the radial direction of the drill shank body 1, and the first outer bevel 12 can be constructed to be inclined from the radial direction of the drill shank body 1 toward the direction away from the step groove 11, so that the width of the step groove 11 gradually increases from the inside to the outside, which is convenient for installing the antenna welding ring 2. The inclination angle of the first outer bevel 12 relative to the radial direction of the drill shank body 1 can be set to A1, and A1 is between 4° and 6°, that is, A1 can be 4°, 5° or 6°, etc., and A1 cannot be too large or too small. If it is too large, the welding length will become longer, increasing the risk of welding defects, and then the strength and reliability of the welding will be reduced. If it is too small, it will be not conducive to the installation of the antenna welding ring 2, which will increase the difficulty of installation.

[0054] At the same time, if Figure 7 As shown, the first inner bevel 22 is tilted relative to the radial direction of the antenna welding ring 2 so that the first inner bevel 22 can be close to the first outer bevel 12, so as to facilitate the connection of the first inner bevel 22 and the first outer bevel 12 by welding. The radial inclination angle of the first inner bevel 22 relative to the antenna welding ring 2 can be set to A2, and A2 is between 4° and 6°, that is, A2 can be 4°, 5° or 6°, etc., and A2 cannot be too large or too small. If it is too large, it will easily cause interference between the first inner bevel 22 and the first outer bevel 12, which is not conducive to the installation of the antenna welding ring 2. If it is too small, it will cause the distance between the first inner bevel 22 and the first outer bevel 12 to increase, which is not conducive to connecting the drill collar body 1 with the antenna welding ring 2 by welding.

[0055] Furthermore, the second outer bevel 13 and the second inner bevel 23 can jointly define a filler welding groove 24 for accommodating solder. The second outer bevel 13 is tilted relative to the radial direction of the drill collar body 1, that is, the second outer bevel 13 is constructed to be tilted from the radial direction of the drill collar body 1 toward a direction away from the step groove 11, and the second inner bevel 23 is tilted relative to the radial direction of the antenna welding ring 2, and the inclination direction of the second inner bevel 23 is opposite to that of the second outer bevel 13, so that the second inner bevel 23 can jointly define the filler welding groove 24 with the second outer bevel 13, and the width of the filler welding groove 24 can gradually increase from the inside to the outside.

[0056] Furthermore, the radial inclination angle of the second outer bevel 13 relative to the drill shank body 1 can be set to B1, and the radial inclination angle of the second inner bevel 23 relative to the antenna welding ring 2 can be set to B2, and both B1 and B2 are between 25° and 35°, that is, B1 and B2 can both be 25°, 30° or 35°, etc., so as to form a filler welding groove 24, and both B1 and B2 should not be too large or too small. If it is too large, the required solder will increase, which will lead to increased costs. If it is too small, the solder will not be able to be fully filled into the filler welding groove 24, affecting the connection strength and connection reliability between the drill shank body 1 and the antenna welding ring 2.

[0057] In some embodiments, and: A1=A2; and / or, B1=B2.

[0058] Specifically, A1 is the radial inclination angle of the first outer bevel 12 relative to the drill collar body 1, and A2 is the radial inclination angle of the first inner bevel 22 relative to the antenna welding ring 2. When A1=A2, the inclination angles of the first outer bevel 12 and the first inner bevel 22 can be equal, and the first outer bevel 12 and the first inner bevel 22 can be parallel, so as to ensure that the drill collar body 1 and the antenna welding ring 2 can be heated evenly during the welding process, so as to reduce welding defects caused by uneven heat distribution, and reduce uneven thermal expansion during welding, thereby reducing welding stress and reducing the possibility of cracks in the weld.

[0059] Also, B1 is the radial inclination angle of the second outer bevel 13 relative to the drill shank body 1, and B2 is the radial inclination angle of the second inner bevel 23 relative to the antenna welding ring 2. By making B1=B2, the inclination angles of the second outer bevel 13 and the second inner bevel 23 can be made equal, and the filler welding groove 24 can be constructed as a V-shaped groove, so that the filler welding groove 24 is radially symmetrical relative to the drill shank body 1. In this way, the solder can flow into and fill the filler welding groove 24 more easily, and the risk of unfusion or over-strengthening can be reduced, thereby improving the connection reliability between the drill shank body 1 and the antenna welding ring 2.

[0060] It should be noted that a small gap may be left at the bottom of the V-groove to ensure that the bottom is fully melted during welding, thereby improving the welding quality, that is, ensuring the connection reliability between the drill collar body 1 and the antenna welding ring 2.

[0061] In some embodiments, the outer peripheral wall of the antenna welding ring 2 is provided with a receiving slot 25 , which is open toward the step groove 11 , and the inner wall of the receiving slot 25 and the inner wall of the step groove 11 together define the antenna receiving cavity 21 .

[0062] Specifically, the accommodating slot 25 is used to accommodate the antenna. The accommodating slot 25 can be constructed to be recessed inward from the outer peripheral wall of the antenna welding ring 2 so that the accommodating slot 25 can have a certain depth, so that the antenna can be set inside the accommodating slot 25 to achieve the installation of the antenna, and the accommodating slot 25 is opened toward the step groove 11, so that the antenna can be inserted into the accommodating slot 25, so that the inner wall of the accommodating slot 25 can jointly define the antenna accommodating cavity 21 with the inner wall of the step groove 11, that is, the antenna can be set between the accommodating slot 25 and the step groove 11, that is, between the antenna welding ring 2 and the drill shank body 1, so that the antenna can be installed and protected together with the antenna welding ring 2 and the drill shank body 1, thereby improving the reliability and service life of the antenna.

[0063] In some embodiments, a first outer arc surface 14 is provided in the step groove 11 between the first outer bevel 12 and the second outer bevel 13, and the antenna welding ring 2 also has a first inner arc surface 26 between the first inner bevel 22 and the accommodating notch 25 and between the second inner bevel 23 and the accommodating notch 25, and the first outer arc surface 14 and the first inner arc surface 26 are clearance-matched.

[0064] Specifically, the first outer arc surface 14 is arranged between the first outer inclined surface 12 and the second outer inclined surface 13, and the first inner arc surface 26 is arranged between the first inner inclined surface 22 and the second inner inclined surface 23 and the accommodating groove 25, and the first outer arc surface 14 and the first inner arc surface 26 can be arranged relative to each other, so that when the antenna welding ring 2 is installed in the step groove 11, the first outer arc surface 14 can cooperate with the first inner arc surface 26, and the first outer arc surface 14 and the first inner arc surface 26 are clearance-fitted, that is, there is a certain distance between the first outer arc surface 14 and the first inner arc surface 26 to serve as a deformation space for the antenna welding ring 2 to adapt to the deformation of the antenna welding ring 2 during welding, thereby ensuring the connection reliability between the antenna welding ring 2 and the drill collar body 1.

[0065] It should be noted that, Figure 5 As shown, the accommodating notch 25 is located between the two first inner arc surfaces 26 , that is, the first outer arc surface 14 can be gap-matched with the first inner arc surfaces 26 on both sides of the accommodating notch 25 to accommodate the deformation of the antenna welding ring 2 .

[0066] In some embodiments, the gap width between the first outer arc surface 14 and the first inner arc surface 26 is L, and satisfies: 0.4 mm≤L≤0.6 mm.

[0067] Specifically, the first outer arc surface 14 and the first inner arc surface 26 are clearance-fitted, and the clearance between the first outer arc surface 14 and the first inner arc surface 26 can be set to L, and L is between 0.4 mm and 0.6 mm, that is, L can be 0.4 mm, 0.5 mm or 0.6 mm, etc., and L cannot be too large or too small. If it is too large, the structural stability of the drill shank body 1 or the antenna welding ring 2 will be reduced, and the risk of deformation of the drill shank body 1 or the antenna welding ring 2 will be increased. If it is too small, the reserved deformation space will be too small, so that the deformation of the antenna welding ring 2 during welding exceeds the reserved deformation space, affecting the connection reliability between the antenna welding ring 2 and the drill shank body 1.

[0068] In some embodiments, a second outer arc surface 15 is provided in the step groove 11 between the first outer bevel 12 and / or the second outer bevel 13 and the accommodating notch 25, and the antenna welding ring 2 is also provided with a second inner arc surface 27 between the first inner bevel 22 and / or the second inner bevel 23 and the accommodating notch 25, and the second outer arc surface 15 is in contact with the second inner arc surface 27.

[0069] Specifically, the second outer arc surface 15 is arranged between the first outer bevel 12 and / or the second outer bevel 13 and the accommodating groove 25, and the second inner arc surface 27 is arranged between the first inner bevel 22 and / or the second inner bevel 23 and the accommodating groove 25, and the second outer arc surface 15 and the second inner arc surface 27 can be arranged relative to each other, so that when the antenna welding ring 2 is installed in the step groove 11, the second outer arc surface 15 can be matched with the second inner arc surface 27 one by one, and the second outer arc surface 15 can be fitted with the second inner arc surface 27 to ensure the connection reliability between the second outer arc surface 15 and the second inner arc surface 27, and thus the connection reliability between the drill shank body 1 and the antenna welding ring 2 can be ensured.

[0070] For example, Figure 3 and Figure 5 As shown, a second outer arc surface 15 is provided between the first outer bevel 12, the second outer bevel 13 and the receiving slot 25, and a second inner arc surface 27 is provided between the first inner bevel 22, the second inner bevel 23 and the receiving slot 25, so that the drill collar body 1 and the antenna welding ring 2 can be fitted and connected at two positions at the same time, thereby improving the connection reliability between the two.

[0071] In some embodiments, the antenna welding ring 2 includes at least two sub-welding segments 28 , and the at least two sub-welding segments 28 are sequentially spliced ​​along the circumference of the antenna welding ring 2 .

[0072] Specifically, the antenna welding ring 2 includes at least two sub-welding segments 28, that is, the number of sub-welding segments 28 can be two, three or more, so that the antenna can be installed and protected together by at least two sub-welding segments 28, thereby improving the reliability and service life of the antenna, and the at least two sub-welding segments 28 are spliced ​​in sequence along the circumference of the antenna welding ring 2, so that the at least two sub-welding segments 28 can be sequentially arranged in the step groove 11 to realize the connection between the drill shank body 1 and the antenna welding ring 2, and by splicing at least two sub-welding segments 28 in sequence, the reliability of the antenna welding ring 2 in protecting the antenna can be improved, and the service life of the antenna can be effectively extended.

[0073] It should be noted that, in Figure 1 In the illustrated embodiment, the antenna welding ring 2 includes two sub-welding segments 28, and the antenna welding ring 2 can be divided into two sub-welding segments 28 by wire cutting, ensuring that the cutting gap is about 0.5 mm to ensure processing accuracy. Setting the sub-welding segments 28 to two can reduce the number of structural parts and reduce assembly steps.

[0074] In some embodiments, the drill collar body 1 is further provided with an electromagnetic wave releasing slot 16 extending along the axial direction, and the electromagnetic wave releasing slot 16 passes through the step groove 11 and is connected with the antenna accommodating cavity 21 .

[0075] Specifically, the electromagnetic wave release slot 16 is a key structure of the antenna for receiving and transmitting signals. In the transmitting mode, the antenna converts the electrical signal into electromagnetic waves and radiates them through the electromagnetic wave release slot 16. In the receiving mode, the antenna receives electromagnetic waves from space through the electromagnetic wave release slot 16 and converts them into electrical signals. Connecting the electromagnetic wave release slot 16 with the antenna accommodating cavity 21 helps to reduce energy loss and improve the radiation efficiency of the antenna. In addition, by passing the electromagnetic wave release slot 16 through the step groove 11, the electromagnetic wave release slot 16 can be extended along the axial direction of the drill collar body 1 to be perpendicular to the setting direction of the antenna, and the antenna can be set in the middle position of the electromagnetic wave release slot 16 to ensure the symmetry of the electromagnetic wave radiation, thereby maximizing the radiation efficiency of the antenna.

[0076] And, if Figure 8-Figure 9 As shown, a plurality of electromagnetic wave release slots 16 can be milled along the circumference of the drill collar body 1, and the plurality of electromagnetic wave release slots 16 can be evenly distributed along the circumference of the drill collar body 1 to increase the radiation area, thereby improving the radiation efficiency, and the smaller the width of the electromagnetic wave release slot 16 and the greater the number of electromagnetic wave release slots 16 set along the circumference of the drill collar body 1, the better the measurement effect of the downhole resistivity instrument 100 can be ensured.

[0077] Also, it should be noted that machining allowances are reserved on the outer circumferential walls of the drill shank body 1 and the antenna welding ring 2 so that the drill shank body 1 and the antenna welding ring 2 can be finely machined to the designed dimensions by a lathe, and the reserved machining allowances can reduce the effects of welding deformation and uneven outer circles.

[0078] In some embodiments, the first inner bevel 22 and the first outer bevel 12 are fixed by fusion welding; the second inner bevel 23 and the second outer bevel 13 are fixed by full filler welding.

[0079] Specifically, the antenna welding ring 2 can be installed in the step groove 11 to realize the connection between the antenna welding ring 2 and the drill collar body 1. When the antenna welding ring 2 is set in the step groove 11, the first inner bevel 22 can be opposite to and fit with the first outer bevel 12, and the second inner bevel 23 can be opposite to the second outer bevel 13 and define a filler welding groove 24. The first inner bevel 22 and the first outer bevel 12 can be welded and fixed by a fusion welding process to realize the connection between the first inner bevel 22 and the first outer bevel 12, and the second inner bevel 23 and the second outer bevel 13 can be welded and fixed by a filler full welding method, that is, solder can be added to the filler welding groove 24, and then the second inner bevel 23 and the second outer bevel 13 are welded and connected by a filler full welding method to realize the connection between the second inner bevel 23 and the second outer bevel 13.

[0080] Therefore, the first outer bevel 12 and the first inner bevel 22 can be connected to the second outer bevel 13 and the second inner bevel 23 by different welding methods, which can improve the connection strength between the drill shank body 1 and the antenna welding ring 2, and release the welding stress to reduce the possibility of cracks in the weld between the drill shank body 1 and the antenna welding ring 2, thereby improving the connection reliability between the two.

[0081] Among them, it should be noted that the first outer bevel 12 and the first inner bevel 22 can adopt materialless welding with a small penetration depth to ensure that the penetration depth does not exceed 1.2 mm, so as to avoid excessive penetration depth, which may lead to overheating of welding, make the weld brittle, and increase the risk of welding defects such as cracks and pores. Moreover, the drill shank body 1 and the antenna welding ring 2 can both adopt non-magnetic, highly corrosion-resistant P550 stainless steel material to reduce the impact on the antenna and improve the reliability of the antenna. The solder can also be selected from the same material as the drill shank body 1 and the antenna welding ring 2 to ensure welding quality and efficiency.

[0082] The invention also provides a forming method of a downhole resistivity instrument.

[0083] like Fig.10 As shown, according to the molding method of the downhole resistivity instrument of the present invention, the molding method is applicable to the downhole resistivity instrument 100 of any of the above embodiments, and the molding method includes:

[0084] S10: forming a step groove 11 on the drill collar body 1 .

[0085] Specifically, the downhole resistivity instrument 100 is used to determine the resistivity of underground rock formations. The antenna is installed in the downhole resistivity instrument 100 as a key component for receiving and transmitting signals, and the antenna welding ring 2 can jointly define an antenna accommodating cavity 21 with the drill collar body 1 for installing the antenna. That is, the drill collar body 1 can be connected to the antenna welding ring 2 so that the two can jointly define the antenna accommodating cavity 21. When the antenna welding ring 2 is installed on the drill collar body 1, a step groove 11 can be first formed on the drill collar body 1. The step groove 11 is used to provide an installation position for the antenna welding ring 2. The antenna welding ring 2 can be installed in the step groove 11 to achieve the coordination between the antenna welding ring 2 and the drill collar body 1, and the step groove 11 can be formed on the drill collar body 1 using a lathe.

[0086] S20: Install the antenna welding ring 2 in the step groove 11 , and make the first inner bevel 22 face the first outer bevel 12 , and the second inner bevel 23 face the second outer bevel 13 to define a filler welding groove 24 .

[0087] Furthermore, after the step groove 11 is formed on the drill shank body 1, the antenna welding ring 2 can be installed in the step groove 11 to achieve the cooperation between the drill shank body 1 and the antenna welding ring 2. At this time, the first inner bevel 22 can be opposite to the first outer bevel 12, and the second inner bevel 23 can be opposite to the second outer bevel 13 to define a filler welding groove 24, so as to facilitate the first inner bevel 22 and the first outer bevel 12 to be connected with the second inner bevel 23 and the second outer bevel 13 respectively by welding.

[0088] S30: First, the second inner bevel 23 and the second outer bevel 13 are welded and fixed.

[0089] Specifically, after the antenna welding ring 2 is placed in the step groove 11, the second inner bevel 23 can be opposite to the second outer bevel 13 and define a filler welding groove 24. At this time, the second inner bevel 23 can be welded and fixed to the second outer bevel 13 to achieve the connection between the antenna welding ring 2 and the drill shank body 1, so that the antenna welding ring 2 and the drill shank body 1 can define an antenna accommodating cavity 21 for installing the antenna.

[0090] S40: The first inner bevel 22 and the first outer bevel 12 are welded and fixed.

[0091] Moreover, after the antenna welding ring 2 is placed in the step groove 11, the first inner bevel 22 can be opposite to the first outer bevel 12. At this time, after the second inner bevel 23 and the second outer bevel 13 are welded and fixed, the first inner bevel 22 and the first outer bevel 12 can be welded and fixed, so that the antenna welding ring 2 can be connected to the drill shank body 1 at two spaced-apart positions, which can effectively improve the connection strength between the two.

[0092] like Fig.10 As shown, according to the molding method of the downhole resistivity instrument of the present invention, the molding method comprises:

[0093] S30: First, the second inner bevel 23 and the second outer bevel 13 are fixed by welding using a filler full welding method.

[0094] Specifically, after the antenna welding ring 2 is placed in the step groove 11, the second inner bevel 23 can be opposite to the second outer bevel 13 and define a filler welding groove 24. At this time, the second inner bevel 23 and the second outer bevel 13 can be welded and fixed to achieve the connection between the antenna welding ring 2 and the drill shank body 1, and the second inner bevel 23 and the second outer bevel 13 can be welded and fixed by full welding of filler to improve the connection strength between the two.

[0095] S40: The first inner bevel 22 and the first outer bevel 12 are fixed by welding using a fusion welding process.

[0096] Moreover, after the antenna welding ring 2 is placed in the step groove 11, the first inner bevel 22 can be opposite to the first outer bevel 12. At this time, after the second inner bevel 23 and the second outer bevel 13 are welded and fixed, the first inner bevel 22 and the first outer bevel 12 can be welded and fixed, so that the antenna welding ring 2 can be connected to the drill shank body 1 at two spaced-apart positions, which can effectively improve the connection strength between the two. The first inner bevel 22 and the first outer bevel 12 can be welded and fixed by a fusion welding process to form a stress release surface here, release the welding stress, reduce the possibility of cracks at the weld between the drill shank body 1 and the antenna welding ring 2, and improve the connection reliability between the two.

[0097] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0098] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A downhole resistivity instrument, characterized in that: include: A drill collar body, wherein the outer peripheral wall of the drill collar body is formed with a step groove extending in the circumferential direction; An antenna welding ring, the antenna welding ring is installed in the step groove and defines an antenna accommodating cavity together with the drill collar body; Among them, the step groove has a first outer bevel and a second outer bevel relatively distributed in the axial direction, and the antenna welding ring has a first inner bevel and a second inner bevel relatively distributed in the axial direction, the first inner bevel is opposite to and engaged with the first outer bevel, and the second inner bevel is opposite to the second outer bevel and defines a filler welding groove.

2. The downhole resistivity instrument according to claim 1, characterized in that: The first inner inclined surface is arranged parallel to the first outer inclined surface; And / or, an included angle is formed between the second inner bevel and the second outer bevel, and the width of the filler welding groove is configured to gradually increase from the inside to the outside.

3. The downhole resistivity instrument according to claim 2, characterized in that: The radial inclination angle of the first outer bevel relative to the drill collar body is A1, the radial inclination angle of the first inner bevel relative to the antenna welding ring is A2, and the following conditions are satisfied: 4°≤A1≤6°, 4°≤A2≤6°; And / or, the radial inclination angle of the second outer bevel relative to the drill shank body is B1, the radial inclination angle of the second inner bevel relative to the antenna welding ring is B2, the inclination direction of the second inner bevel is opposite to that of the second outer bevel, and satisfies: 25°≤B1≤35°, 25°≤B2≤35°.

4. The downhole resistivity instrument according to claim 3, characterized in that: And satisfy: A1=A2; And / or, B1=B2.

5. The downhole resistivity instrument according to any one of claims 1 to 4, characterized in that: The outer peripheral wall of the antenna welding ring is provided with a receiving notch, the receiving notch is open toward the step groove, and the inner wall of the receiving notch and the inner wall of the step groove jointly define the antenna receiving cavity.

6. The downhole resistivity instrument according to claim 5, characterized in that: A first outer arc surface is provided in the step groove between the first outer bevel and the second outer bevel, and a first inner arc surface is provided between the first inner bevel and the accommodating notch and between the second inner bevel and the accommodating notch of the antenna welding ring, and the first outer arc surface and the first inner arc surface are clearance-matched.

7. The downhole resistivity instrument according to claim 6, characterized in that: The gap width between the first outer arc surface and the first inner arc surface is L, and satisfies: 0.4mm≤L≤0.6mm.

8. The downhole resistivity instrument according to claim 5, characterized in that: A second outer arc surface is provided in the step groove between the first outer bevel and / or the second outer bevel and the accommodating notch, and a second inner arc surface is provided in the antenna welding ring between the first inner bevel and / or the second inner bevel and the accommodating notch, and the second outer arc surface is in contact with the second inner arc surface.

9. The downhole resistivity instrument according to any one of claims 1 to 4, characterized in that: The antenna welding ring includes at least two sub-welding segments, and the at least two sub-welding segments are spliced ​​in sequence along the circumference of the antenna welding ring.

10. The downhole resistivity instrument according to any one of claims 1 to 4, characterized in that: The drill collar body is also provided with an electromagnetic wave release slot extending along the axial direction, and the electromagnetic wave release slot passes through the step groove and is communicated with the antenna accommodating cavity.

11. The downhole resistivity instrument according to any one of claims 1 to 4, characterized in that: The first inner bevel and the first outer bevel are fixed by welding using a fusion welding process; The second inner bevel and the second outer bevel are fixed by welding in a filler full welding manner.

12. A method for forming a downhole resistivity instrument, characterized in that: The molding method is applicable to the downhole resistivity instrument according to any one of claims 1 to 11, and the molding method comprises: A step groove is formed on the drill collar body; Installing the antenna welding ring in the step groove, with the first inner bevel facing the first outer bevel, and the second inner bevel facing the second outer bevel, to define a filler welding groove; Firstly, the second inner bevel and the second outer bevel are welded and fixed; The first inner bevel and the first outer bevel are then fixed by welding.

13. The method for forming a downhole resistivity instrument according to claim 12, characterized in that: The molding method comprises: Firstly, the second inner bevel and the second outer bevel are fixed by welding with filler; The first inner bevel and the first outer bevel are fixed by welding using a fusion welding process.

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