A drill collar

Abstract

The present invention relates to the technical field of oil extraction, and specifically to a drill collar, comprising a drill collar body, an excitation coil and a conductor; the excitation coil is coaxially arranged on the outer surface of the drill collar body, and is used to apply an alternating voltage to the drill collar body; one end of the conductor is connected to the lower end of the drill collar body, and the other end of the conductor is extended from the upper end of the drill collar body after bypassing the outside of the excitation coil and connected to a measuring circuit, so that the measuring circuit measures the lower end of the drill collar body through the conductor. In the above manner, the present invention solves the problem that there is a deviation between the actual voltage at both ends of the drill collar and the voltage at both ends of the drill collar obtained by theoretical calculation based on the primary voltage supplied to the excitation coil, thereby causing inaccurate formation resistivity measurement.

Description

Technical Field

[0001] The invention belongs to the field of petroleum exploitation, and in particular relates to a drill collar. Background Art

[0002] During oil extraction, the environment near the wellbore is very harsh. Generally, the drill collar voltage on both sides of the coil is calculated by collecting the primary voltage supplied to the excitation coil. However, due to the influence of factors such as the well environment and the state of the excitation coil, there is often a deviation between the actual voltage across the drill collar and the voltage across the drill collar obtained by theoretical calculation based on the primary voltage supplied to the excitation coil, which leads to inaccurate formation resistivity measurement. Summary of the invention

[0003] In order to solve the above problems, the present invention aims to provide a drill collar, which solves the problem that the voltage at both ends of the actual drill collar deviates from the primary voltage supplied to the excitation coil, thereby causing inaccurate formation resistivity measurement.

[0004] The present invention provides a drill collar, comprising: a drill collar body, an excitation coil and a conductor; the excitation coil is coaxially arranged on the outer surface of the drill collar body and is used for applying an alternating voltage to the drill collar body; one end of the conductor is connected to the lower end of the drill collar body, and the other end of the conductor is extended from the upper end of the drill collar body after bypassing the outside of the excitation coil and connected to a measuring circuit, so that the measuring circuit measures the lower end of the drill collar body through the conductor.

[0005] By connecting one end of the wire to the lower end of the drill collar body, and the other end bypassing the outside of the excitation coil, extending from the upper end of the drill collar body and connected to the measuring circuit, a wire is also connected to the upper end of the drill collar body, connected to the measuring circuit, so that the voltage actually generated at both ends of the drill collar enters the measuring circuit. After the measuring circuit receives the voltage generated at both ends of the drill collar and the electrical signals measured by the electrodes and the magnetic receiving coil, it analyzes and processes the voltage and current, and finally accurately calculates the formation resistivity and transmits the data to the ground.

[0006] In some embodiments, a coil protective sleeve is provided on the drill collar body, and the coil protective sleeve is coaxially mounted outside the excitation coil to isolate the excitation coil and the conductor from the wellbore mud. The coil protective sleeve is used to protect the excitation coil from damage in a harsh external environment.

[0007] In some embodiments, the conductor includes an upper conductor, a conductor outside the coil, and a lower conductor. A first conductor channel and a second conductor channel are provided inside the drill collar body, the upper conductor is provided in the first conductor channel, the lower conductor is provided in the second conductor channel, the conductor outside the coil is provided outside the excitation coil, and the two ends of the conductor outside the coil are respectively connected to the upper conductor and the lower conductor. By respectively providing the upper conductor and the lower conductor in the first conductor channel and the second conductor channel, and connecting the upper conductor and the lower conductor using the conductor outside the coil, the voltage at the lower end of the drill collar body can be accurately input into the measurement circuit through the conductor, and the voltage transmission will not be affected by the alternating magnetic field of the excitation coil, so that the measurement of the formation resistivity is more accurate.

[0008] In some embodiments, the first wire channel and the second wire channel are respectively provided with a first sealing connector and a second sealing connector at one end close to the excitation coil, the first sealing connector is used to connect one end of the upper wire with one end of the wire outside the coil in the first wire channel, and seal the first wire channel, and one end of the lower wire is connected to the other end of the wire outside the coil in the second wire channel through the second sealing connector. By providing the first sealing connector and the second sealing connector, the three sections of wires, namely the upper wire, the wire outside the coil, and the lower wire, can be connected, so that the voltage at the lower end of the drill collar body can be transmitted to the measurement circuit, and the first sealing connector and the second sealing connector can respectively seal the first wire channel and the second wire channel at one end close to the excitation coil, so that the upper wire in the first wire channel and the lower wire in the second wire channel will not be affected by changes in the external environment of the drill collar.

[0009] In some embodiments, a sealing plug is provided at one end of the second wire channel toward the lower end of the drill collar body, and the sealing plug is connected to the other end of the lower wire. By connecting one end of the lower wire to the sealing plug, the voltage of the lower drill collar can be transmitted through the lower wire and finally transmitted to the measurement circuit.

[0010] In some embodiments, an insulating ring is coaxially arranged at one end of the coil protective sleeve, and a lower fixed sleeve is coaxially arranged at the other end of the coil protective sleeve. The lower fixed sleeve, one end close to the coil protective sleeve, the insulating ring, the coil protective sleeve and the drill collar body together form an annular cavity, and the annular cavity is used to accommodate the excitation coil and the outer conductor of the coil. By providing the insulating ring, the coil protective sleeve is insulated from the upper end of the drill collar body, so as not to affect the formation resistivity measurement. In addition, the annular cavity formed by the end of the lower fixed sleeve close to the coil protective sleeve, the insulating ring, the coil protective sleeve and the drill collar body can make the excitation coil and the outer conductor of the coil in a closed environment, and will not be affected by the changes in the surrounding environment of the drill collar and the rotation generated during the operation of the drill collar. The normal operation of the excitation coil and the normal transmission voltage of the outer conductor of the coil will not be affected.

[0011] In some embodiments, an elastic insulating material is sealed in the annular cavity, and the elastic insulating material seals and isolates the excitation coil and the outer conductor of the coil separately, so that the excitation coil, the outer conductor of the coil and the drill collar body are insulated from each other. By filling the annular cavity with elastic insulating material, the excitation coil, the outer conductor of the coil and the drill collar body are insulated from each other, and the coil protective cover is insulated from the upper end of the drill collar body, so that the normal operation of each component in the annular cavity will not affect each other. When the drill collar body is squeezed by external force, the drill collar body will be deformed, thereby compressing other components in the annular cavity. Since the insulating material is elastic, it will produce appropriate deformation to offset the pressure, and will not damage other components in the annular cavity, so that the drill collar can continue to maintain normal operation.

[0012] In some embodiments, the insulating ring is provided with a first protrusion on the surface near one end of the coil protective cover, and the lower fixed cover is provided with a second protrusion on the surface near one end of the coil protective cover, and the two ends of the coil protective cover are respectively sealed on the first protrusion and the second protrusion to form an annular cavity. By providing the first protrusion and the second protrusion, the coil protective cover can be pre-positioned in the installation position during installation, and the coil protective cover can be stably supported. By extending the first protrusion of the insulating ring and the second protrusion of the lower fixed cover into the interior of the coil protective cover, the contact area between the coil protective cover and the insulating ring and the lower fixed cover is increased. When there is liquid outside the coil protective cover, the liquid needs to flow over a longer distance to enter the annular cavity, thereby increasing the sealing performance of the coil protective cover.

[0013] In some embodiments, an annular groove is provided on the end surface of the first convex portion, and an elastic insulating material is filled in the annular groove. By providing an annular groove and filling the elastic insulating material inside the annular groove, the contact area between the elastic insulating material filled in the annular space and the insulating ring is increased, and the overall sealing is better. When the coil protective cover is squeezed by external force, in the absence of the annular groove, the elastic insulating material in the annular cavity will be stressed and deformed, thereby causing the contact surface between the elastic insulating material and the insulating ring to tear. In this embodiment, since an annular groove is provided and the annular groove is filled with elastic insulating material, a part of the deformed elastic insulating material is deformed and acts on the annular groove, reducing the degree of tearing of the contact surface between the elastic insulating material and the insulating ring, thereby protecting the sealing of the elastic insulating material in the annular cavity, and avoiding the elastic insulating material and other structures around the annular cavity due to elastic deformation. Large gaps are generated.

[0014] In some embodiments, an upper fixing sleeve is coaxially arranged on one side of the upper end of the drill collar body near the insulating ring, and an upper fixing member and a lower fixing member are respectively arranged on the upper fixing sleeve and the lower fixing sleeve, and the upper fixing member and the lower fixing member are used to fix the upper fixing sleeve and the lower fixing sleeve on the drill collar body. The insulating ring and the coil protective sleeve are fixed by the upper fixing sleeve and the lower fixing sleeve together, so that the insulating ring and the coil protective sleeve will not move. When an external force acts on the surface of the drill collar, the upper fixing member and the lower fixing member fix the upper fixing sleeve and the lower fixing sleeve on the drill collar body, so that the insulating ring and the coil protective sleeve between the upper fixing sleeve and the lower fixing sleeve are fixed on the drill collar body and will not move, thereby ensuring the stability of the internal structure of the drill collar.

[0015] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings:

[0017] Figure 1 A schematic diagram of the drill collar structure provided by an embodiment of the present invention is shown;

[0018] Figure 2 A schematic diagram of a partially enlarged structure of an annular cavity in a drill collar provided by an embodiment of the present invention is shown;

[0019] Figure 3 A schematic diagram of the top view structure of a drill collar provided in an embodiment of the present invention is shown.

[0020] Drill collar 100, drill collar body 110, upper end 111 of drill collar body, lower end 112 of drill collar body, first wire channel 113, upper wire 113a, second wire channel 114, lower wire 114a, excitation coil 120, coil protection sleeve 130, first sealing connector 140, second sealing connector 150, sealing plug 160, insulating ring 170, first protrusion 171, groove 172, upper fixing sleeve 180, upper fixing member 181, lower fixing sleeve 190, lower fixing member 191, second protrusion 192, annular cavity 200, coil outer wire 210. DETAILED DESCRIPTION

[0021] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0023] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] In the description of the embodiments of the present invention, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention.

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

[0029] The drill collar is an important component of the lower drilling tools for oil production. It is mainly used to make the drill bit work smoothly. During drilling, it is necessary to measure the formation resistivity in real time to obtain the situation of the formation around the drill bit. The resistivity of materials with different structures in the formation is generally different. For example, porous formations generally have higher resistivity, which can indicate the presence of hydrocarbons. When porous formations show lower resistivity, it generally indicates the presence of saturated water.

[0030] During oil extraction, the environment near the wellbore is very harsh. Existing drill collars do not have potential monitoring devices. Generally, the voltage of the drill collar on both sides of the coil can only be calculated by collecting the primary voltage supplied to the excitation coil. However, due to the influence of factors such as the well environment and the state of the excitation coil, the actual voltage at both ends of the drill collar often deviates from the primary voltage supplied to the excitation coil, resulting in inaccurate formation resistivity measurement.

[0031] In order to ensure that the formation resistivity can be accurately measured, the present invention provides a drill collar, which opens a wire channel inside the drill collar body, uses the wire to lead the voltage at the lower end of the drill collar body to the upper end of the drill collar body through the wire channel, the upper end of the drill collar body is also connected with a wire, and a measuring circuit is respectively connected to the wire at the upper end of the drill collar body and the wire at the lower end of the drill collar body. The voltage at both ends of the drill collar is measured by the measuring circuit, thereby achieving accurate measurement of the actual voltage at both ends of the drill collar, thereby accurately calculating the formation resistivity.

[0032] See also Figure 1 , Figure 1 A structural schematic diagram of a drill collar 100 is provided for one embodiment, wherein the drill collar 100 includes a drill collar body 110, an excitation coil 120 and a conductive wire; the excitation coil 120 is coaxially arranged on the outer surface of the drill collar body 110, and is used to apply an alternating voltage to the drill collar body 110; one end of the conductive wire is connected to the lower end of the drill collar body 110, and the other end of the conductive wire bypasses the outside of the excitation coil 120 and extends from the upper end of the drill collar body 110 to be connected to a measuring circuit, so that the measuring circuit measures the lower end of the drill collar body 110 through the conductive wire.

[0033] It should be noted that the measuring circuit is not shown in the figure, and the measuring circuit is used to measure the voltage between the upper end 111 of the drill collar body and the lower end 112 of the drill collar body.

[0034] The excitation coil 120 can be a spiral ring coil, which is coaxially mounted on the drill collar body 110. The two ends of the excitation coil 120 are connected to the transmitting circuit board through a watertight head. The transmitting circuit board is used to provide alternating current to the primary winding of the excitation coil 120, so that an alternating voltage is generated at both ends of the drill collar body 110 on both sides of the excitation coil 120. The drill collar 100 and the soil form an integral loop, which includes the drill collar 100 and the stratum around the drill collar 100.

[0035] The drill collar body 110 is generally also provided with an electrode and a magnetic receiving coil, which are used to measure the electrical signal generated after the current enters the formation from the upper end 111 of the drill collar body and then returns from the lower end 112 of the drill collar body. The voltage measured by the measuring circuit and the electrical signal are analyzed and calculated to obtain the formation resistivity.

[0036] It should be noted that the wire needs to bypass the outside of the excitation coil 120, because if the wire passes directly through the inside of the excitation coil 120, an alternating magnetic field will be generated due to the alternating current applied to both ends of the excitation coil 120, which will in turn affect the voltage in the wire.

[0037] By connecting one end of the wire to the lower end 112 of the drill collar body, and the other end bypassing the outside of the excitation coil 120, extending from the upper end 111 of the drill collar body, and connecting to the measuring circuit, the upper end 111 of the drill collar body is also connected with a wire, which is connected to the measuring circuit, so that the voltage actually generated at both ends of the drill collar 100 enters the measuring circuit. After the measuring circuit receives the voltage generated at both ends of the drill collar 100 and the electrical signals measured by the electrodes and the magnetic receiving coil, the voltage and current are analyzed and processed, and finally the formation resistivity is accurately calculated, and the data is transmitted to the ground.

[0038] Please refer again Figure 1 In some embodiments, a coil protection cover 130 is disposed on the drill collar body 110 , and the coil protection cover 130 is coaxially mounted outside the excitation coil 120 to isolate the excitation coil 120 and the conductor from the wellbore mud.

[0039] The width of the coil protection cover 130 can be set to be wider than the width of the excitation coil 120 to fully protect the coil protection cover 130 .

[0040] The coil protection cover 130 is used to protect the excitation coil 120 from being damaged in a harsh external environment.

[0041] Please continue reading Figure 1In some embodiments, the conductor includes an upper conductor 113a, a coil outer conductor 210 and a lower conductor 114a. A first conductor channel 113 and a second conductor channel 114 are provided inside the drill collar body 110. The upper conductor 113a is provided in the first conductor channel 113, the lower conductor 114a is provided in the second conductor channel 114, the coil outer conductor 210 is provided outside the excitation coil 120, and both ends of the coil outer conductor 210 are respectively connected to the upper conductor 113a and the lower conductor 114a.

[0042] The first wire channel 113 and the second wire channel 114 are used to accommodate the upper wire 113a and the lower wire 114a respectively. The upper wire 113a is used to connect the measurement circuit and the coil outer wire 210. The coil outer wire 210 is arranged outside the excitation coil 120, and is used to connect the upper wire 113a and the lower wire 114a without affecting the voltage accuracy, so as to transmit the voltage of the lower wire 114a to the upper wire 113a. One end of the lower wire 114a is used to connect the coil outer wire 210, and the other end is used to connect the lower end 112 of the drill collar body, so as to transmit the actual voltage of the lower end 112 of the drill collar body to the measurement circuit.

[0043] By respectively arranging an upper conductor 113a and a lower conductor 114a in the first conductor channel 113 and the second conductor channel 114, and connecting the upper conductor 113a and the lower conductor 114a with the coil outer conductor 210, the voltage at the lower end 112 of the drill collar body can be accurately input into the measurement circuit through the conductor, and the voltage transmission will not be affected by the alternating magnetic field of the excitation coil 120, so that the measurement of the formation resistivity is more accurate.

[0044] Please continue reading Figure 1 In some embodiments, the first wire channel 113 and the second wire channel 114 are respectively provided with a first sealing connector 140 and a second sealing connector 150 at one end close to the excitation coil 120. The first sealing connector 140 is used to connect one end of the upper wire 113a with one end of the coil external wire 210 in the first wire channel 113 and seal the first wire channel 113. One end of the lower wire 114a is connected to the other end of the coil external wire 210 in the second wire channel 114 through the second sealing connector 150.

[0045] The first sealing connector 140 and the second sealing connector 150 can be connectors with sealing functions, such as watertight heads. The first sealing connector 140 and the second sealing connector 150 respectively seal one end of the first wire channel 113 and the second wire channel 114, and one end of the upper wire 113a and one end of the coil outer wire 210 are connected through the first sealing connector 140, and the other end of the coil outer wire 210 is connected to one end of the lower wire 114a through the second sealing connector 150.

[0046] By setting the first sealing connector 140 and the second sealing connector 150, the three sections of wires, namely the upper wire 113a, the coil outer wire 210, and the lower wire 114a, can be connected, so that the voltage at the lower end 112 of the drill collar body can be transmitted to the measurement circuit, and the first sealing connector 140 and the second sealing connector 150 can respectively seal the first wire channel 113 and the second wire channel 114 at one end close to the excitation coil 120, so that the upper wire 113a in the first wire channel 113 and the lower wire 114a in the second wire channel 114 will not be affected by changes in the external environment of the drill collar 100.

[0047] Please continue reading Figure 1 In some embodiments, a sealing plug 160 is disposed at one end of the second wire channel 114 facing the lower end 112 of the drill collar body, and the sealing plug 160 is connected to the other end of the lower wire 114a.

[0048] The sealing plug 160 is used to seal the second wire channel 114. One end of the lower wire 114a is connected to the sealing plug 160. The sealing plug 160 has the function of making the electric potential of the lower end 112 of the drill collar body equivalent to the lower wire 114a. By doing so, the voltage of the lower drill collar 100 can be transmitted through the lower wire 114a and finally transmitted to the measuring circuit.

[0049] See also Figure 1 and Figure 2 , Figure 2 A locally enlarged structural schematic diagram of the annular cavity 200 in the drill collar 100 provided in an embodiment of the present invention. In some embodiments, an insulating ring 170 is coaxially arranged at one end of the coil protection sleeve 130, and a lower fixing sleeve 190 is coaxially arranged at the other end of the coil protection sleeve 130. The lower fixing sleeve 190 is close to one end of the coil protection sleeve 130, the insulating ring 170, the coil protection sleeve 130 and the drill collar body 110 together constitute an annular cavity 200, and the annular cavity 200 is used to accommodate the excitation coil 120 and the coil outer conductor 210.

[0050] The insulating ring 170 is adjacent to the coil protection cover 130 and is used to insulate the drill collar 100 from the surrounding strata. The lower fixing cover 190 is adjacent to the coil protection cover 130 and is used to fix the coil protection cover 130 .

[0051] By providing the insulating ring 170, the coil protection sleeve 130 is insulated from the upper end 111 of the drill collar body, thereby not affecting the measurement of the formation resistivity. In addition, the annular cavity 200 formed by the lower fixing sleeve 190 close to one end of the coil protection sleeve 130, the insulating ring 170, the coil protection sleeve 130 and the drill collar body 110 can keep the excitation coil 120 and the coil outer conductor 210 in a closed environment, and the normal operation of the excitation coil 120 and the normal voltage transmission of the coil outer conductor 210 will not be affected by changes in the environment around the drill collar 100 and the rotation generated during the operation of the drill collar 100.

[0052] Please refer again Figure 2 In some embodiments, an elastic insulating material is sealed in the annular cavity 200, and the elastic insulating material seals and isolates the excitation coil 120 and the coil outer conductor 210 separately, so that the excitation coil 120, the coil outer conductor 210 and the drill collar body 110 are insulated from each other and the coil protection cover 130 is insulated from the upper end 111 of the drill collar body.

[0053] Specifically, the elastic insulating material may be rubber.

[0054] By filling the annular cavity 200 with elastic insulating material, the excitation coil 120, the coil outer conductor 210 and the drill collar body 110 are insulated from each other, and the coil protective cover 130 is insulated from the upper end 111 of the drill collar body, so that the normal operation of each component in the annular cavity 200 will not affect each other. When the drill collar body 110 is squeezed by external force, the drill collar body 110 will deform, thereby pressing other components in the annular cavity 200. Since the insulating material is elastic, it will produce appropriate deformation to offset the pressure, and will not damage other components in the annular cavity 200, so that the drill collar 100 can continue to maintain normal operation.

[0055] Please continue reading Figure 2 In some embodiments, a first protrusion 171 is provided on the surface of the insulating ring 170 near one end of the coil protection cover 130, and a second protrusion 192 is provided on the surface of the lower fixing cover 190 near one end of the coil protection cover 130. Both ends of the coil protection cover 130 are sealed on the first protrusion 171 and the second protrusion 192 to form an annular cavity 200.

[0056] By providing the first protrusion 171 and the second protrusion 192, the coil protective cover 130 can be pre-positioned during installation, and the coil protective cover 130 can be firmly supported. The first protrusion 171 of the insulating ring 170 and the second protrusion 192 of the lower fixing cover 190 extend into the interior of the coil protective cover 130, thereby increasing the contact area between the coil protective cover 130 and the insulating ring 170 and the lower fixing cover 190. When there is liquid outside the coil protective cover 130, the liquid needs to flow over a longer distance to enter the annular cavity 200, thereby improving the sealing performance of the coil protective cover 130.

[0057] When the drill collar 100 is working, a large amount of mud will be produced with the surrounding soil. The external environment of the drill collar 100 is harsh, and mud and other impurities wrap the outer surface of the drill collar 100. Since the insulating ring 170 and a part of the lower fixed sleeve 190 extend under the coil protection sleeve 130, the distance between the mud outside the drill collar 100 and the annular cavity 200 is relatively far, making it more difficult for mud and other impurities to enter the annular cavity 200, thereby improving the overall sealing of the drill collar 100.

[0058] Please continue reading Figure 2 In some embodiments, an annular groove 172 is provided on the end surface of the first protrusion 171 , and the elastic insulating material is filled in the annular groove 172 .

[0059] By providing an annular groove 172 and filling the annular groove 172 with elastic insulating material, the contact area between the elastic insulating material filled in the annular space and the insulating ring 170 is increased, and the overall sealing is better. When the coil protection cover 130 is squeezed by external force, in the absence of the annular groove 172, the elastic insulating material in the annular cavity 200 will be stressed and deformed, thereby causing the contact surface between the elastic insulating material and the insulating ring 170 to tear. In this embodiment, since the annular groove 172 is provided and the annular groove 172 is filled with elastic insulating material, a part of the deformed elastic insulating material is deformed in the annular groove 172, thereby reducing the degree of tearing of the contact surface between the elastic insulating material and the insulating ring 170, thereby protecting the sealing of the elastic insulating material in the annular cavity 200, and avoiding the generation of a large gap between the elastic insulating material and other structures around the annular cavity 200 due to elastic deformation.

[0060] See also Figure 1 and Figure 3 , Figure 3A top view of a drill collar 100 is provided in an embodiment of the present invention. In some embodiments, an upper fixing sleeve 180 is coaxially arranged on one side of the upper end of the drill collar body 110 close to the insulating ring 170, and an upper fixing member 181 and a lower fixing member 191 are respectively arranged on the upper fixing sleeve 180 and the lower fixing sleeve 190. The upper fixing member 181 and the lower fixing member 191 are used to fix the upper fixing sleeve 180 and the lower fixing sleeve 190 on the drill collar body 110.

[0061] like Figure 1 and Figure 3 As shown, the upper fixing sleeve 180 and the lower fixing sleeve 190 may be provided with grooves matching the upper fixing member 181 and the lower fixing member 191, and the upper fixing member 181 and the lower fixing member 191 are connected to the drill collar body 110 by screws, so that the upper fixing sleeve 180 and the lower fixing sleeve 190 are fixed on the drill collar body 110. The number of the upper fixing member 181 and the lower fixing member 191 can be multiple, which can be evenly distributed along the outer circumference of the drill collar 100 or symmetrically distributed.

[0062] When external force acts on the surface of the drill collar 100, the upper fixing member 181 and the lower fixing member 191 fix the upper fixing sleeve 180 and the lower fixing sleeve 190 on the drill collar body 110, so that the insulating ring 170 and the coil protection sleeve 130 between the upper fixing sleeve 180 and the lower fixing sleeve 190 are fixed on the drill collar body 110 and will not move, thereby ensuring the stability of the internal structure of the drill collar 100.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A drill collar, characterized in that: include: Drill collar body, excitation coil and conductor; The excitation coil is coaxially arranged on the outer surface of the drill collar body and is used to apply an alternating voltage to the drill collar body; One end of the wire is connected to the lower end of the drill collar body, and the other end is extended from the upper end of the drill collar body after passing the outside of the excitation coil to be connected to the measuring circuit, so that the measuring circuit measures the lower end of the drill collar body through the wire.

2. The drill collar according to claim 1, characterized in that: The drill collar body is provided with a coil protection sleeve, which is coaxially mounted outside the excitation coil and is used to isolate the excitation coil and the conductor from the wellbore mud.

3. The drill collar according to claim 2, characterized in that: The conductors include an upper conductor, a coil outer conductor and a lower conductor; A first wire channel and a second wire channel are provided inside the drill collar body, the upper wire is provided in the first wire channel, the lower wire is provided in the second wire channel, the outer wire of the coil is provided outside the excitation coil, and the two ends of the outer wire of the coil are respectively connected to the upper wire and the lower wire.

4. The drill collar according to claim 3, characterized in that: The first wire channel and the second wire channel are respectively provided with a first sealing connector and a second sealing connector at one end close to the excitation coil; The first sealing connector is used to connect one end of the upper wire with one end of the coil outer wire in the first wire channel and seal the first wire channel; One end of the lower wire is connected to the other end of the coil outer wire in the second wire channel through the second sealing connector.

5. The drill collar according to claim 4, characterized in that: A sealing plug is arranged at one end of the second wire channel facing the lower end of the drill collar body, and the sealing plug is connected to the other end of the lower wire.

6. The drill collar according to claim 3, characterized in that: An insulating ring is coaxially arranged at one end of the coil protection cover, and a lower fixing cover is coaxially arranged at the other end of the coil protection cover; An end of the lower fixing sleeve close to the coil protection sleeve, the insulating ring, the coil protection sleeve and the drill collar body together form an annular cavity, and the annular cavity is used to accommodate the excitation coil and the outer conductor of the coil.

7. The drill collar according to claim 6, characterized in that: The annular cavity is sealed with an elastic insulating material; The elastic insulating material seals and isolates the excitation coil and the coil outer conductor separately, so that the excitation coil, the coil outer conductor and the drill collar body are insulated from each other and the coil protection sleeve is insulated from the upper end of the drill collar body.

8. The drill collar according to claim 7, characterized in that: The insulating ring is provided with a first convex portion on a surface close to one end of the coil protection cover, and the lower fixing cover is provided with a second convex portion on a surface close to one end of the coil protection cover; The two ends of the coil protection cover are respectively sealed and arranged on the first convex part and the second convex part to form the annular cavity.

9. The drill collar according to claim 8, characterized in that: An annular groove is arranged on the end surface of the first protrusion, and the elastic insulating material is filled in the annular groove.

10. The drill collar according to claim 6, characterized in that: An upper fixing sleeve is coaxially arranged on one side of the upper end of the drill collar body close to the insulating ring. An upper fixing piece and a lower fixing piece are respectively arranged on the upper fixing sleeve and the lower fixing piece, and the upper fixing piece and the lower fixing piece are used to fix the upper fixing sleeve and the lower fixing sleeve on the drill collar body.

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