Microwave while-drilling underground communication excitation structure based on protective sleeve

Abstract

The invention discloses a microwave while-drilling downhole communication excitation structure based on a protective sleeve, the microwave while-drilling downhole communication excitation structure comprises a drill rod, a plurality of excitation structures, a plurality of sleeves and a plurality of pins are arranged in the drill rod, the excitation structures are used for exciting a TE11 mode, the sleeves are used for preventing the excitation structures from colliding with other devices, and the pins are used for fixing the positions of the sleeves. According to the invention, a double-excitation structure is adopted, so that the reliability of underground communication of the communication system is enhanced; meanwhile, a sleeve structure is additionally arranged, so that the impact of the measurement-while-drilling tool on excitation when the measurement-while-drilling tool descends a well is avoided while the influence of airflow on the excitation structure is weakened.

Description

Technical Field

[0001] The invention relates to the technical field of downhole communication, and in particular to a microwave downhole communication excitation structure based on a protective sleeve. Background Art

[0002] Microwave communication for downhole while drilling (MCDWD) technology is a new type of measurement while drilling technology data communication method that has emerged in recent years. This technology uses the internal space of the cylindrical drill pipe to transmit electromagnetic waves, and realizes communication between the downhole and the ground through a step-by-step relay method. Compared with traditional measurement while drilling methods such as acoustic waves or mud pulses, microwave transmission is characterized by large data transmission volume, is not easily affected by the external environment, and can achieve real-time transmission.

[0003] Domestic and foreign scholars have conducted a lot of research on microwave communication while drilling, which has led to the rapid development of this technology. Domestic scholars have proposed the microwave transmission while drilling measurement technology in the bore of the drill string. At present, there are also many research results on microwave transmission technology in pipes in China. In 2010, Chen Yijian and others proposed the idea of ​​microwave transmission while drilling measurement technology in the bore of the drill string, regarded the drill pipe as an ideal circular waveguide, and analyzed the transmission characteristics of microwaves in the drill pipe. In 2012, the Underbalanced Laboratory of Southwest Petroleum University successfully developed a microwave transmission test machine, and in the field test, the transmission rate and transmission distance can meet the needs of gas drilling while drilling measurement, and further established a drill pipe joint microwave transmission test platform in 2016, which has guiding significance for the design of microwave transmission while drilling monitoring system.

[0004] However, the existing communication excitation structure cannot meet the needs of complex downhole environments and is easily affected by high-speed airflow downhole, resulting in communication obstruction or interruption. Summary of the invention

[0005] The purpose of the present invention is to provide a microwave downhole communication excitation structure based on a protective sleeve to solve the technical problem of how to improve the reliability of downhole communication.

[0006] The present invention is implemented by adopting the following technical scheme: a microwave downhole communication excitation structure based on a protective sleeve, comprising a drill pipe, wherein a plurality of excitation structures, a plurality of sleeves and a plurality of pins are arranged in the drill pipe, wherein the excitation structure is used to excite TE 11 The mold and sleeve are used to prevent the excitation structure from colliding with other devices, and the pin is used to fix the position of the sleeve.

[0007] Furthermore, two orthogonal excitation structures are arranged in the drill pipe, and the excitation structures include a first annular excitation and a second annular excitation, and sleeves are arranged at both ends of the first annular excitation and the second annular excitation.

[0008] Furthermore, the sleeve includes a first nylon sleeve, a second nylon sleeve and a third nylon sleeve, wherein a first annular excitation is arranged between the first nylon sleeve and the second nylon sleeve, and a second annular excitation is arranged between the second nylon sleeve and the third nylon sleeve.

[0009] Furthermore, the first nylon sleeve is provided with a first metal pin and a second metal pin; the second nylon sleeve is provided with a third metal pin and a fourth metal pin; and the third nylon sleeve is provided with a fifth metal pin and a sixth metal pin.

[0010] Furthermore, the excitation structure adopts a 50Ω coaxial structure for feeding.

[0011] Furthermore, the side surfaces of the first nylon sleeve, the second nylon sleeve and the third nylon sleeve are all provided with inclined surfaces, and the angle between the inclined surfaces and the horizontal direction of the sleeve is θ.

[0012] Furthermore, the first metal pin, the second metal pin, the third metal pin, the fourth metal pin, the fifth metal pin and the sixth metal pin are made of copper.

[0013] The beneficial effects of the present invention are as follows: the present invention adopts a dual excitation structure to enhance the reliability of the communication system in underground communication; at the same time, a sleeve structure is added to reduce the impact of airflow on the excitation structure and avoid the impact of the while-drilling measurement tool on the excitation when it is lowered into the well. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0015] Figure 1 It is a side view of the present invention; Figure 2 It is a front view of the present invention; Figure 3 This is a comparison chart of the effect of sleeve length on the copper pin excitation structure; Figure 4 This is a comparison chart of the effect of sleeve slope on the copper pin excitation structure; Figure 5This is a comparison chart of the effect of sleeve diameter on the copper pin excitation structure; Figure 6 A comparison chart showing the effect of sleeve position on the copper pin excitation structure; Figure 7 This is a comparison chart of the best results for a single copper pin excitation structure; Figure 8 Comparison of the best results for two copper pin excitation structures; In the figure, 1-first nylon sleeve, 2-first input signal, 3-first annular excitation, 4-second nylon sleeve, 5-second input signal, 6-third nylon sleeve, 7-fifth metal pin, 8-second annular excitation, 9-first metal pin, 10-third metal pin, 11-second metal pin, 12-fourth metal pin, 13-sixth metal pin. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0017] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0018] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0019] See also Figure 1 , Figure 2 A microwave downhole communication excitation structure based on a protective sleeve comprises a drill pipe, wherein a plurality of excitation structures, a plurality of sleeves and a plurality of pins are arranged in the drill pipe, wherein the excitation structure is used to excite TE 11 The mold and sleeve are used to prevent the excitation structure from colliding with other devices, and the pin is used to fix the position of the sleeve.

[0020] In this embodiment, the drill pipe is based on the 5-inch API standard drill pipe. The overall structure mainly includes three parts: the excitation structure, the sleeve and the pin. The excitation structure is used to excite the TE 11 Each excitation structure has a circular nylon sleeve structure on both sides, which can play a certain buffering role to prevent the excitation structure from colliding with other devices. Each sleeve has several pins to stabilize the position of the sleeve. 11The mode is linearly polarized, so two orthogonal excitation structures are designed in a relay. Even if the drill pipe rotates underground, it can be guaranteed that at least one excitation structure receives the signal. If one of the structures is damaged, the existence of the other excitation structure can also ensure the continuity of communication.

[0021] Specifically, two orthogonal excitation structures are arranged in the drill pipe, and the excitation structures include a first annular excitation 3 and a second annular excitation 8. One end of the first annular excitation 3 is connected to the first input signal 2, and one end of the second annular excitation 8 can be connected to the second input signal 5. The sleeve includes a first nylon sleeve 1, a second nylon sleeve 4 and a third nylon sleeve 6, wherein the first annular excitation 3 is arranged between the first nylon sleeve 1 and the second nylon sleeve 4, and the second annular excitation 8 is arranged between the second nylon sleeve 4 and the third nylon sleeve 6.

[0022] The first annular excitation 3 and the second annular excitation 8 are fed by a 50 Ω coaxial structure. The inner core of the coaxial line extends into the waveguide through a metal cuboid and then passes through the circular waveguide wall from the other end. The outer conductor diameter of the coaxial line is 4 mm and the inner core diameter is 1.5 mm.

[0023] Furthermore, the first nylon sleeve 1 is provided with a first metal pin 9 and a second metal pin 11, wherein the first metal pin 9 and the second metal pin 11 are arranged opposite to each other; the second nylon sleeve 4 is provided with a third metal pin 10 and a fourth metal pin 12, wherein the third metal pin 10 and the fourth metal pin 12 are arranged opposite to each other; the third nylon sleeve 6 is provided with a fifth metal pin 7 and a sixth metal pin 13, wherein the fifth metal pin 7 and the sixth metal pin 13 are arranged opposite to each other.

[0024] The first nylon sleeve 1, the second nylon sleeve 4 and the third nylon sleeve 6 have the same structure. The first nylon sleeve 1 is taken as an example for explanation: the outer diameter of the first nylon sleeve 1 is 40 mm, the inner diameter is 24 mm, and the sleeve length is L1. At the same time, in practical applications, the side of the sleeve needs to be processed into a bevel, so as to ensure that other downhole measurement devices can smoothly enter the drill pipe. The angle between the bevel and the horizontal direction of the sleeve is the inclination angle θ. The first metal pin 9 has a diameter of b and a length of a, and the distance from the edge of the pin to the edge of the sleeve is L2. The addition of sleeve and pin structures will produce discontinuous parasitic parameters in the circular waveguide, thereby affecting the return loss and transmission efficiency. When selecting the material of the pin, copper is mainly considered.

[0025] Simulation experiment The sleeve length will affect the excitation effect. By changing only L1, the simulated S 22 like Figure 3 As shown in Figure 1, when L1 increases within a certain range, the return loss will also increase.

[0026] When the sleeve's tilt angle is different, the return loss is also different. Figure 4 is S for different sleeve inclination angles 22 From the comparison diagram, it can be seen that the return loss increases as the tilt angle decreases, but at the same time, the decrease in the tilt angle will also cause the frequency to decrease.

[0027] The effect of pin thickness on return loss is as follows: Figure 5 As shown, b is the diameter of the pin. Within a certain range, the larger the diameter, the thicker the pin and the smaller the return loss.

[0028] The effect of pin position change on return loss is as follows: Figure 6 As shown, within a certain range, the smaller L2 is, the closer the pin is to the excitation structure, and the smaller the return loss is.

[0029] Considering that the operating frequency of the excitation structure is 2.4-2.5 GHz, the best result of a single copper pin is finally obtained. Figure 7 As shown, at 2.42-2.5 GHz the return loss S 22 Less than -10 dB.

[0030] Another pin is set at the symmetrical position of each sleeve pin to enhance the fixing effect. The best result obtained by optimization is as follows Figure 8 As shown, the return loss S in the 2.44-2.5 GHz frequency band 22 In addition, due to the asymmetric structure of transmission in two directions, S 12 With S 32 The amplitude difference is large. Although this will reduce the transmission efficiency, it is far less than the attenuation of the signal in the drill pipe and is within an acceptable range. Figure 7 and Figure 8 The results show that the signal transmission efficiency S 12 With S 32 There are large fluctuations in the working frequency band. Since underground communication requires low data transmission volume and low bandwidth, it is not sensitive to amplitude fluctuations.

[0031] The present invention designs a new dual excitation structure suitable for gas drilling environment around microwave downhole communication while drilling, and uses a nylon sleeve to reduce the influence of airflow on the excitation structure, so as to avoid the impact on the excitation when the downhole measurement tool is lowered into the well.

[0032] It should be noted that the terms "connection" and "setting" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "connection" and "setting" may explicitly or implicitly include one or more of the features. Moreover, the terms "connection", "setting" and the like are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. And for the aforementioned embodiments, for the sake of simple description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited to the described order of actions, because according to the present application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification belong to preferred embodiments, and the actions involved are not necessarily required by the present application.

[0033] The above embodiments describe the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the changes and modifications made by those skilled in the art shall be within the scope of protection of the appended claims of the present invention without departing from the spirit and scope of the present invention.

Claims

1. A microwave downhole communication excitation structure based on a protective sleeve, characterized in that: The drill rod comprises a plurality of excitation structures, a plurality of sleeves and a plurality of pins, wherein the excitation structure is used to excite the TE 11 The mold and sleeve are used to prevent the excitation structure from colliding with other devices, and the pin is used to fix the position of the sleeve.

2. A microwave downhole communication excitation structure based on a protective sleeve as claimed in claim 1, characterized in that: Two orthogonal excitation structures are arranged in the drill rod, the excitation structures comprising a first annular excitation (3) and a second annular excitation (8), and sleeves are arranged at both ends of the first annular excitation (3) and the second annular excitation (8).

3. A microwave downhole communication excitation structure based on a protective sleeve as claimed in claim 2, characterized in that: The sleeve comprises a first nylon sleeve (1), a second nylon sleeve (4) and a third nylon sleeve (6), wherein a first annular excitation (3) is arranged between the first nylon sleeve (1) and the second nylon sleeve (4), and a second annular excitation (8) is arranged between the second nylon sleeve (4) and the third nylon sleeve (6).

4. A microwave downhole communication excitation structure based on a protective sleeve as claimed in claim 3, characterized in that: The first nylon sleeve (1) is provided with a first metal pin (9) and a second metal pin (11); the second nylon sleeve (4) is provided with a third metal pin (10) and a fourth metal pin (12); and the third nylon sleeve (6) is provided with a fifth metal pin (7) and a sixth metal pin (13).

5. The microwave downhole communication excitation structure based on the protective sleeve according to claim 4, characterized in that: The excitation structure adopts a 50Ω coaxial structure for feeding.

6. A microwave downhole communication excitation structure based on a protective sleeve as claimed in claim 5, characterized in that: The side surfaces of the first nylon sleeve (1), the second nylon sleeve (4) and the third nylon sleeve (6) are all provided with inclined surfaces, and the angle between the inclined surfaces and the horizontal direction of the sleeves is θ.

7. A microwave downhole communication excitation structure based on a protective sleeve as claimed in claim 6, characterized in that: The first metal pin (9), the second metal pin (11), the third metal pin (10), the fourth metal pin (12), the fifth metal pin (7) and the sixth metal pin (13) are made of copper.

Images