A button electrode and collar for borehole resistivity measurement while drilling

Abstract

The application relates to a button electrode and a drill collar for a while-drilling azimuthal resistivity measurement, which comprises a measuring electrode, an electrical unit, an insulator, a seal, an electrode cover plate, a plurality of conductive columns, a cabin body and an insulating pad; the plurality of conductive columns are arranged at the upper end of the measuring electrode; the measuring electrode, the insulator and the electrode cover plate are fixedly connected with the cabin body; the insulator is arranged between the measuring electrode and the electrode cover plate, and the electrode cover plate presses the insulator, and the insulator presses the measuring electrode; the insulator and the measuring electrode are provided with the seal at the matching position, and the insulator and the electrode cover plate are provided with the seal at the matching position; the electrical unit is arranged in a containing cavity formed by the measuring electrode and the cabin body, and the electrical unit is electrically connected with the measuring electrode; and the containing cavity is filled with a fluid medium. Under the conditions of high temperature, high pressure, high erosion and vibration in the well, the structure of the button electrode is more sealed, more insulating, more stable and longer in working time than the structure of the injection-molded button electrode in the prior art.

Description

A button electrode and drill collar for azimuth resistivity measurement while drilling Technical Field

[0001] This invention relates to a button electrode and drill collar for measuring azimuth resistivity while drilling. Background Technology

[0002] With the continuous depletion of easily exploitable oil and gas resources, the development of these resources is becoming increasingly difficult. To develop oil and gas resources more efficiently, it is necessary to obtain more reservoir geological information to more accurately locate oil reservoirs. Reservoir geological parameters generally include drill bit resistivity, azimuth resistivity, gamma ray, and porosity. Among these parameters, azimuth resistivity is directional, accurately determining the direction of the oil layer. Geological engineers use azimuth resistivity to guide directional drilling tools to accurately drill into the target oil and gas layer and remain within the reservoir. Utilizing azimuth resistivity while drilling (WDD) facilitates precise geological guidance during the drilling process, playing a crucial role in improving oil and gas recovery rates and reducing operating costs and risks. Button electrodes are used to measure azimuth resistivity and can also achieve azimuth resistivity imaging, providing data for precise geological guidance and forming an important structure of WDD instruments. Summary of the Invention

[0003] To enrich the types of button electrodes in the existing technology and improve their insulation performance, this invention proposes a button electrode and drill collar for azimuth resistivity measurement while drilling. The technical solution proposed by this invention is as follows:

[0004] In a first aspect, the present invention provides a button electrode for measuring azimuth resistivity while drilling, applied to a drill collar, comprising: a measuring electrode, an electrical unit, a seal, an insulator, an electrode cover plate, multiple conductive posts, a chamber, and an insulating pad;

[0005] The plurality of conductive pillars are disposed at the upper end of the measuring electrode, and at least a portion of the conductive pillars extends out of the outer surface of the measuring electrode;

[0006] The measuring electrode, the insulator, and the electrode cover are all fixedly connected to the cabin body, and the insulating pad is provided between the measuring electrode and the cabin body;

[0007] The insulator is disposed between the measuring electrode and the electrode cover plate, and the electrode cover plate presses against the insulator, and the insulator presses against the measuring electrode;

[0008] The sealing element is provided at the position where the insulator mates with the measuring electrode and at the position where the insulator mates with the electrode cover plate;

[0009] The electrical unit is disposed within the cavity formed by the measuring electrode and the cabin body, and the electrical unit is electrically connected to the measuring electrode;

[0010] The cavity is filled with a fluid medium.

[0011] In some embodiments, the outer surface of the insulator is lower than the outer surface of the measuring electrode and the outer surface of the electrode cover.

[0012] In some embodiments, the outer surface of the measuring electrode and the outer surface of the electrode cover plate are both consistent with the curvature of the outer surface of the cabin.

[0013] In some embodiments, a protruding post is provided at the bottom end of the receiving cavity, and the electrical unit is sleeved on the protruding post.

[0014] In some embodiments, a wire plug is also included;

[0015] The upper end of the measuring electrode is provided with a fluid channel for injecting the fluid medium, and the fluid channel is connected to the receiving cavity;

[0016] The plug seals the end of the fluid channel away from the receiving cavity, and the plug is in contact with the protrusion.

[0017] In some embodiments, the measuring electrode is rectangular elliptical in shape.

[0018] In some embodiments, a sealing pin is also included; a stepped inclined hole is provided in the receiving groove of the housing that houses the electrical unit, and the sealing pin is installed in the stepped inclined hole;

[0019] One end of the sealing pin is connected to the electrical unit, and the other end is used to connect to the circuit board of the cabin.

[0020] In some embodiments, screws are also included;

[0021] The electrode cover plate is provided with multiple countersunk holes, and the screws are disposed in the countersunk holes. The electrode cover plate is fixed to the cabin or the drill collar by the screws.

[0022] In some embodiments, the nut of the screw is below the lowest point of the countersunk hole.

[0023] In some embodiments, the measuring electrode is threadedly connected to the insulator, and a thread-bonding adhesive is provided between the measuring electrode and the insulator.

[0024] In some embodiments, the conductive post and the measuring electrode are connected by a threaded connection or an interference fit.

[0025] In some embodiments, the insulator has a predetermined thickness.

[0026] In a second aspect, the present invention provides a drill collar, comprising a button electrode for measuring azimuth resistivity while drilling as described in the first aspect;

[0027] The outer surface of the measuring electrode has the same curvature as the outer surface of the drill collar.

[0028] Thirdly, the present invention provides a method for measuring azimuth resistivity while drilling, using the drill collar as described in the second aspect.

[0029] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0030] This invention provides a button electrode for azimuth resistivity measurement while drilling. The measuring electrode, insulator, and electrode cover are all fixedly connected to the chamber. The insulator is positioned between the measuring electrode and the electrode cover, with the electrode cover pressing against the insulator, and the insulator pressing against the measuring electrode. Pressure is transmitted layer by layer, securely fixing the insulator and measuring electrode. The overall structure is compact, ensuring the button electrode structure is securely fixed to the chamber, guaranteeing the measurement of azimuth resistivity while drilling. By filling the cavity with a fluid medium, the high-pressure static sealing level is improved, effectively preventing high-pressure mud from intruding into the mating surface between the measuring electrode and the chamber. Sealing elements are provided at the mating points of the insulator and the measuring electrode, as well as at the mating points of the insulator and the electrode cover, preventing high-pressure mud from entering the mating surfaces of the insulator and the measuring electrode, ensuring high sealing performance of the button electrode, thereby guaranteeing insulation performance and extending the service life of the insulator. Compared to the injection-molded button electrodes in the prior art, the button electrode structure of this invention has stronger sealing, higher insulation, more reliable stability, and longer working time under the conditions of high temperature, high pressure, high erosion, and vibration in downhole drilling.

[0031] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 is a three-dimensional structural diagram of a button electrode for azimuth resistivity measurement while drilling provided in an embodiment of the present invention.

[0035] Figure 2 is a cross-sectional view of a button electrode for azimuth resistivity measurement while drilling provided in an embodiment of the present invention;

[0036] Figure 3 is a top view of a button electrode for azimuth resistivity measurement while drilling provided in an embodiment of the present invention;

[0037] Figure 4 is a partial structural diagram of the drill collar provided in an embodiment of the present invention;

[0038] Figure 5 is a cross-sectional view of the drill collar provided in an embodiment of the present invention;

[0039] In the diagram: 1 is the measuring electrode, 2 is the electrical unit, 3 is the seal, 4 is the insulator, 5 is the electrode cover, 6 is the fluid channel, 7 is the receiving cavity, 8 is the conductive post, 9 is the chamber, 10 is the insulating pad, 11 is the plug, 12 is the countersunk hole, 13 is the screw, 14 is the sealing pin, 15 is the drill collar, 16 is the circuit board, and 17 is the protrusion. Detailed Implementation

[0040] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Horizontal wells offer the advantage of increased drainage area, and their development is increasing annually, with horizontal sections trending towards larger lengths. Extended reach horizontal wells produce 5-8 times more oil than conventional horizontal wells, but they also present numerous technical challenges. In particular, the tripping process severely damages the wellbore in long horizontal sections, potentially leading to downhole safety accidents. Therefore, there is an urgent need to develop technologies for drilling long horizontal sections in a single trip. The inventors discovered that long horizontal sections require button electrodes to measure azimuth resistivity, providing precise geological guidance to the drilling instrument near the drill bit. These button electrodes, in contact with the wellbore, are subjected to erosion from high-pressure drilling mud. Existing button electrodes exhibit rapid insulation degradation, leading to measurement failure and forced tripping, failing to meet the inventors' expectations. Developing a button electrode that can operate normally downhole for extended periods is a pressing issue that needs to be addressed.

[0045] The current research status of this type of button electrode structure is as follows:

[0046] In the invention patent (authorization announcement number: CN 10781634 B), the main electrode and the shielding electrode are filled with high-temperature wear-resistant insulating materials such as fiberglass or rubber. The fiberglass insulation layer is made of high-temperature and high-pressure resistant epoxy resin, and the rubber insulation layer is made of fluororubber. The VARTM technology, which involves vacuuming and then injecting resin with an injection molding machine, is used to wrap the fiberglass insulation layer around the polytetrafluoroethylene coating. The rubber insulation layer is filled by uniformly pressing and molding the rubber layer with a special mold and attaching it to the gap between the shielding electrode and the main electrode.

[0047] The invention patent (application announcement number: CN 111810122 A) discloses a button electrode structure for a logging-while-drilling resistivity imaging instrument, in which the measuring electrode, insulating layer, electrode cover, and electrical pin are all injection molded into one piece through a special process.

[0048] The inventors discovered that the insulation structure of the aforementioned measuring electrodes uses an injection-molded integrated structure. Common defects in the injection molding process include shrinkage cavities and microcracks. Especially with button electrodes, which are small in size and require limited injection space, the irregular internal cavity structure presents challenges to injection quality. Furthermore, the harsh and complex downhole conditions, with severe erosion, pose a threat to insulation. Because there is no sealing structure between the rubber or fiberglass injection molding materials and the measuring electrodes or drill collars, the bonding strength between these materials and the drill collars or electrodes relies primarily on the adhesion strength between the rubber or fiberglass and the metal. Under prolonged high-pressure mud erosion, once the adhesion strength decreases, the seal fails, leading to insulation failure, which does not meet the inventors' expectations. Through further research and development, the inventors created this invention.

[0049] Example 1

[0050] This invention provides a button electrode for measuring azimuth resistivity while drilling, applied to a drill collar. As shown in Figures 1, 2 and 3, it includes: a measuring electrode 1, an electrical unit 2, a sealing element 3, an insulator 4, an electrode cover plate 5, multiple conductive posts 8, a chamber 9 and an insulating pad 10.

[0051] The plurality of conductive posts 8 are disposed at the upper end of the measuring electrode 1, and at least a portion of the conductive posts 8 extends beyond the outer surface of the measuring electrode 1. As a conductive metal, the measuring electrode 1 is in direct contact with the well wall. To improve the wear resistance of the measuring electrode 1, this invention designs wear-resistant conductive posts 8 on the surface of the measuring electrode 1. The conductive posts 8 are made of wear-resistant conductive materials, which improves both wear resistance and conductivity, establishing a wear-resistant conductive protective layer for the measuring electrode 1 and enhancing both conductivity and wear resistance.

[0052] Referring to Figure 2, the measuring electrode 1, the insulator 4, and the electrode cover plate 5 are all fixedly connected to the chamber 9, and an insulating pad 10 is provided between the measuring electrode 1 and the chamber 9. The chamber 9 has a metal rectangular plate structure, and the insulating pad 10 provides insulation between the measuring electrode 1 and the chamber 9.

[0053] The insulator 4 is disposed between the measuring electrode 1 and the electrode cover plate 5, and the electrode cover plate 5 presses the insulator 4, and the insulator 4 presses the measuring electrode 1.

[0054] The sealing element 3 is provided at the mating positions of the insulator 4 and the measuring electrode 1, and at the mating positions of the insulator 4 and the electrode cover plate 5. The sealing element 3 at the mating positions of the insulator 4 and the measuring electrode 1 prevents high-pressure slurry from entering the mating surface between the insulator 4 and the measuring electrode 1; the sealing element 3 at the mating positions of the insulator 4 and the electrode cover plate 5 prevents high-pressure slurry from entering the mating surface between the insulator 4 and the electrode cover plate 5; and the sealing element 3 at the mating positions of the insulator 4 and the chamber 9 prevents high-pressure slurry from entering the mating surface between the insulator 4 and the chamber 9. A composite sealing process is used between the measuring electrode 1, the electrode cover plate 5, the insulator 4, and the chamber 9 to ensure the high sealing performance of the button electrode, thereby guaranteeing its insulation performance. In this embodiment of the invention, the sealing element 3 is composed of a retaining ring and a high-temperature resistant rubber combination, and the assembly method follows the "Mechanical Handbook".

[0055] The electrical unit 2 is disposed in the cavity 7 formed by the measuring electrode 1 and the cabin 9, and the electrical unit 2 is electrically connected to the measuring electrode 1;

[0056] The receiving cavity 7 is filled with fluid medium 2. The use of an internally filled, pressure-resistant fluid medium improves the high-pressure static sealing level of the button electrode and effectively prevents high-pressure slurry from intruding into the mating surface. The aforementioned liquid medium is a pressure-resistant flowing medium, such as hydraulic oil or silicone oil.

[0057] In this embodiment of the invention, the electrode cover plate 5 is a metal rectangular plate structure, and the outer surface of the electrode cover plate 5 is a cylindrical side with the same arc as the drill collar 15 to prevent it from bumping against the well wall or getting stuck.

[0058] This invention relates to the field of oil and gas drilling technology, specifically to a button electrode for measuring azimuth resistivity while drilling, designed to improve the service life and reliability of the button electrode and meet the requirements for long-term stable operation in oil and gas well drilling environments. The measuring electrode 1, insulator 4, and electrode cover plate 5 are all fixedly connected to the chamber 9. The insulator 4 is positioned between the measuring electrode 1 and the electrode cover plate 5, with the electrode cover plate 5 pressing against the insulator 4, and the insulator 4 pressing against the measuring electrode 1. Pressure is transmitted layer by layer, securely fixing the insulator 4 and the measuring electrode 1. The overall structure is compact, ensuring the button electrode structure is securely fixed to the chamber 9, guaranteeing the measurement of azimuth resistivity while drilling. By filling the receiving cavity 7 with a fluid medium, the high-pressure static sealing level is improved, effectively preventing high-pressure mud from intruding into the mating surface between the measuring electrode 1 and the chamber 9. Sealing elements 3 are provided at the mating positions of the insulator 4 and the measuring electrode 1, as well as at the mating positions of the insulator 4 and the electrode cover plate 5. These seals prevent high-pressure mud from entering the mating surfaces of the insulator 4 and the measuring electrode 1, and between the insulator 4 and the electrode cover plate 5, ensuring the high sealing performance of the button electrode and thus guaranteeing its insulation performance. Furthermore, this extends the service life of the insulator 4. Compared to existing injection-molded button electrodes, where there is no sealing structure between the rubber or fiberglass injection-molded materials and the measuring electrode or drill collar, the bonding strength between these materials and the drill collar or electrode relies primarily on the adhesive strength between the rubber or fiberglass and the metal. Under prolonged high-pressure mud erosion, this adhesive strength decreases, leading to sealing failure and insulation failure. The button electrode provided by this invention, however, maintains its sealing performance even under high temperature, high pressure, high erosion, and vibration conditions downhole, offering higher insulation, more reliable stability, and longer operating time.

[0059] The button electrode for azimuth resistivity measurement while drilling provided in this invention is easier to assemble, disassemble, and maintain than existing technologies, saving time and effort and improving applicability and reliability. The insulator 4 is an independent part, without the need for an integrated injection-molded structure with the measuring electrode 1 and the housing 9, eliminating the need for molds, equipment, and processes associated with injection molding, reducing labor intensity, and improving efficiency. Furthermore, as an independent structure, the button electrode can be arranged individually or in multiples on the measurement-while-drilling instrument, enabling azimuth resistivity imaging logging, fine reservoir evaluation for fracture identification, and geological guidance, providing guidance for the development of complex and unconventional reservoirs. Currently, the structure of this invention has been applied in the field. The button electrode is resistant to high temperatures, high pressures, and erosion, provides accurate measurement data, has stable and reliable performance, and demonstrates good results. This invention has achieved azimuth resistivity imaging, utilizing the imaging logging images provided by the button electrode to improve geological guidance and fine evaluation of complex high-resistivity reservoirs such as fractured, high-density, low-porosity, and low-permeability reservoirs, significantly improving drilling encounter rates and recovery rates.

[0060] In one specific embodiment, referring to FIG3, the insulator 4 is a stepped cylinder with a smaller top and a larger bottom, and the insulator 4 has a stepped structure;

[0061] The electrode cover plate 5 is disposed on the stepped structure and presses against the insulator 4.

[0062] Referring to Figure 2, sealing grooves are provided on the stepped surface and the side surface of the stepped structure, and the sealing element 3 is disposed in the sealing groove. A sealing groove is also provided on the side surface of the lower large cylinder, and the sealing element 3 is placed within the sealing groove. This sealing element 3 is used to prevent high-pressure mud from entering from the mating surface between the insulator 4 and the measuring electrode 1.

[0063] In a specific embodiment, referring to Figures 1 and 2, the outer surface of the insulator 4 is lower than the outer surface of the measuring electrode 1 and the outer surface of the electrode cover plate 5. The insulator 4 is a non-metallic, non-conductive material, and compared to metals, it lacks wear resistance. The fact that the outer surface of the insulator 4 is lower than the outer surfaces of the measuring electrode 1 and the electrode cover plate 5 ensures that the insulator 4 will not be worn by the well wall, thus guaranteeing its insulating performance and improving its service life, thereby increasing the overall service life of the button electrode.

[0064] In a specific embodiment, referring to FIG1, the outer surfaces of the measuring electrode 1 and the electrode cover plate 5 are both curved to the same degree as the outer surface of the chamber 9. Since the measuring electrode 1 and the electrode cover plate 5 are in direct contact with the wellbore wall during azimuth resistivity measurement, designing the outer surfaces of both the measuring electrode 1 and the electrode cover plate 5 to be curved to the same degree as the chamber 9 helps protect the measuring electrode 1 from impact with the wellbore wall. The shape of the measuring electrode 1 can be set according to the shape of the electrode cover plate 5 and the chamber 9. For example, the outer surface of the measuring electrode 1 can be a cylindrical side surface with the same outer diameter as the chamber 9 or the drill collar 15, preventing it from bumping against the wellbore wall and getting stuck, while minimizing the distance between the measuring electrode 1 and the formation.

[0065] In one specific embodiment, a protrusion 17 is provided at the bottom of the receiving cavity 7, and the electrical unit 2 is sleeved on the protrusion 17. The receiving cavity 7 is a large groove formed by the bottom groove of the measuring electrode 1 and the chamber 9. The electrical unit 2 is sleeved on the protrusion 17 to fix the electrical unit 2. The plug 11 is made of a conductive metal material. The electrical unit 2 is sleeved on the protrusion 17 and integrated into a ring-shaped electrical integrated block on the protrusion 17. The plug 11 fits closely to the protrusion 17, which can transmit the signal collected by the measuring electrode 1 to the electrical unit 2. All electrical components are integrated into one piece inside the button electrode, which helps to fix the circuit assembly of the button electrode. The circuit assembly has the shortest wiring and greatly reduces the internal power consumption of the circuit.

[0066] In a specific embodiment, referring to FIG2, a plug 11 is further included. A fluid channel 6 for injecting the fluid medium is provided at the upper end of the measuring electrode 1, and the fluid channel 6 communicates with the receiving cavity 7. The plug 11 seals the end of the fluid channel 6 away from the receiving cavity 7, and the plug 11 is in contact with the protrusion 17. The fluid channel 6 is tightened using a plug 11 with sealing properties.

[0067] In one specific embodiment, referring to FIG1, the measuring electrode 1 is rectangular elliptical in shape. The shape of the measuring electrode 1 is designed as a rectangular ellipse with semi-circular transitions at both ends, which facilitates the assembly of the sealing element 3 and improves the sealing reliability.

[0068] In one specific embodiment, referring to Figures 4 and 5, a sealing pin 14 is also included; a stepped inclined hole (not shown in the figure) is provided in the receiving groove of the housing 9 that accommodates the electrical unit 2, and the sealing pin 14 is installed in the stepped inclined hole;

[0069] One end of the sealing pin 14 is connected to the electrical unit 2, and the other end is used to connect to the circuit board 16 of the cabin 9.

[0070] Electrical unit 2 is a current transformer that senses the current flowing into the button electrode. Sealing pin 14 connects to both electrical unit 2 and circuit board 16 inside the cabin 9, collecting the azimuth resistivity signal acquired by electrical unit 2 onto circuit board 16, which then transmits the signal to the ground. Sealing pin 14 provides isolation, preventing mud from flowing out of the button electrode and into the cabin 9's tank, and preventing mud from flowing into the button electrode's interior, thus providing dual protection. Sealing pin 14 is selected for its high pressure resistance.

[0071] In one specific embodiment, referring to FIG1, a screw 13 is also included;

[0072] The electrode cover plate 5 is provided with a plurality of countersunk holes 12, and the screws 13 are provided in the countersunk holes 12. The electrode cover plate 5 is fixed to the cabin 9 or the drill collar 15 by the screws 13.

[0073] Screws 13 are used to fasten the electrode cover plate 5. Tightening the screws 13 to a certain torque ensures that the electrode cover plate 5 presses against the insulator 4. The electrode cover plate 5 presses against the insulator 4, and the insulator 4 presses against the measuring electrode 1, transmitting pressure layer by layer to safely fix the insulator 4 and the measuring electrode 1. The overall structure is compact and ingenious, ensuring the button electrode structure is safely fixed to the chamber 9, guaranteeing the safety and sealing of the button electrode structure. The number of countersunk holes 12 can be set according to actual needs; this invention does not impose a specific limitation. Referring to Figure 1, the electrode cover plate 5 is provided with seven countersunk holes 12. Screws 13 are installed in the countersunk holes 12 and fixed together with the chamber 9 or the drill collar 15. The screws 13 in this invention are internal hexagonal head screws 13, which are easy to disassemble.

[0074] In one specific embodiment, the nut of the screw 13 is lower than the lowest point of the countersunk hole 12. This lowering of the nut of the screw 13 below the lowest point of the countersunk hole 12 solves the problem of the screw 13 becoming loose or difficult to disassemble due to it hitting the well wall, and ensures that the nut is not worn.

[0075] In one specific embodiment, the measuring electrode 1 is threadedly connected to the insulator 4, and a thread-locking adhesive is provided between the measuring electrode 1 and the insulator 4. The measuring electrode 1 has an external thread, and the insulator 4 has a corresponding internal thread. The connection between the measuring electrode 1 and the insulator 4 prevents the threads from loosening due to vibration. Applying thread-locking adhesive before connection further improves the sealing between the measuring electrode 1 and the insulator 4.

[0076] In one specific embodiment, the conductive post 8 and the measuring electrode 1 are connected by a threaded connection or an interference fit.

[0077] In one specific embodiment, the insulator 4 has a preset thickness. The insulator 4 is a prefabricated component, and based on the design principle of button electrodes, the thickness of the insulator 4 can be set according to actual needs to ensure the insulation performance of the insulator 4.

[0078] The button electrode of this invention has azimuth characteristics and must be used in conjunction with a sensor for measuring azimuth, such as an accelerometer. The azimuth sensor is also mounted on the cabin 9. The azimuth is determined based on the data signal from the accelerometer, and then the azimuth resistivity is determined based on the current signal obtained from the button electrode at that azimuth.

[0079] In this embodiment of the invention, the insulator 4 is made of a special high-polymer solid insulating material for aerospace applications, such as PTFE and polyimide. PTFE and polyimide materials have good electrical insulation properties; they possess mechanical properties, exhibiting rigidity and toughness, and are particularly outstanding in their fatigue resistance under alternating stress; they are corrosion resistant, with stable performance under acidic and alkaline conditions; and they have very low shrinkage and high dimensional stability.

[0080] Example 2

[0081] Based on the same inventive concept, this embodiment of the invention also provides a drill collar 15, as shown in Figures 4 and 5, which includes a button electrode for measuring azimuth resistivity while drilling as described in any of the foregoing embodiments, wherein the outer surface of the measuring electrode 1 has the same curvature as the outer surface of the drill collar 15.

[0082] Button electrodes are arranged on drill collar 15. The button electrodes on drill collar 15 are used to realize the azimuth resistivity measurement while drilling to form imaging logging images, which improves the geological guidance and fine evaluation of complex high-resistivity reservoirs such as fractures, high-density layers, low porosity, and low permeability, and greatly improves the drilling encounter rate and recovery rate.

[0083] Example 3

[0084] This invention provides a method for measuring azimuth resistivity while drilling, using the drill collar 15 as described in the foregoing embodiments.

[0085] The drill collar 15 provided in the above embodiments can be used to measure the azimuth resistivity while drilling. The specific measurement process can be referred to the specific description in the prior art, which will not be repeated here.

[0086] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "upper," "lower," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0087] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. This invention is not limited to any single aspect, nor to any single embodiment, nor to any combination and / or substitution of these aspects and / or embodiments. Each aspect and / or embodiment of this invention can be used alone, or in combination with one or more other aspects and / or other embodiments.

[0088] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A button electrode for measuring azimuth resistivity while drilling, applied to a drill collar, characterized in that, include: Measuring electrode (1), electrical unit (2), sealing element (3), insulator (4), electrode cover plate (5), multiple conductive posts (8), chamber (9), insulating pad (10), and plug (11); the multiple conductive posts (8) are disposed at the upper end of the measuring electrode (1), and at least a portion of the conductive posts (8) extends out of the outer surface of the measuring electrode (1); the measuring electrode (1), the insulator (4), and the electrode cover plate (5) are all fixedly connected to the chamber (9), and the insulating pad (10) is disposed between the measuring electrode (1) and the chamber (9); the insulator (4) is disposed between the measuring electrode (1) and the electrode cover plate (5), and the electrode cover plate (5) presses the insulator (4), and the insulator (4) presses the measuring electrode (1); the mating position of the insulator (4) and the measuring electrode (1), and the insulating pad (11) are also specified. The insulator (4) and the electrode cover plate (5) are both provided with the sealing element (3); the electrical unit (2) is provided in the cavity (7) formed by the measuring electrode (1) and the chamber (9), and the electrical unit (2) is electrically connected to the measuring electrode (1); the cavity (7) is filled with a fluid medium; the outer surface of the insulator (4) is lower than the outer surface of the measuring electrode (1) and the outer surface of the electrode cover plate (5); a protrusion (17) is provided at the bottom end of the cavity (7), and the electrical unit (2) is sleeved on the protrusion (17); a fluid channel (6) for injecting the fluid medium is provided at the upper end of the measuring electrode (1), and the fluid channel (6) is connected to the cavity (7); the plug (11) seals the end of the fluid channel (6) away from the cavity (7), and the plug (11) is in contact with the protrusion (17).

2. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, The outer surface of the measuring electrode (1) and the outer surface of the electrode cover plate (5) are both consistent with the curvature of the outer surface of the cabin (9).

3. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, The measuring electrode (1) is rectangular elliptical in shape.

4. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, It also includes a sealing pin (14); the compartment (9) has a stepped inclined hole in the receiving groove for accommodating the electrical unit (2), and the sealing pin (14) is installed in the stepped inclined hole; one end of the sealing pin (14) is connected to the electrical unit (2), and the other end is used to connect to the circuit board (16) of the compartment (9).

5. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, It also includes screws (13); the electrode cover plate (5) is provided with multiple countersunk holes (12), the screws (13) are provided in the countersunk holes (12), and the electrode cover plate (5) is fixed to the cabin (9) or the drill collar by the screws (13).

6. The button electrode for azimuth resistivity measurement while drilling according to claim 5, characterized in that, The nut of the screw (13) is below the lowest point of the countersunk hole (12).

7. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, The measuring electrode (1) is threadedly connected to the insulator (4), and a thread adhesive is provided between the measuring electrode (1) and the insulator (4).

8. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, The conductive post (8) and the measuring electrode (1) are connected by a threaded connection or an interference fit.

9. The button electrode for azimuth resistivity measurement while drilling according to claim 1, characterized in that, The insulator (4) has a preset thickness.

10. A drill collar, characterized in that, Includes a button electrode for measuring azimuth resistivity while drilling as described in any one of claims 1-9; the outer surface of the measuring electrode (1) has the same curvature as the outer surface of the drill collar.

11. A method for measuring azimuth resistivity while drilling, characterized in that, Use the drill collar as described in claim 10.

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