Insulated antenna for electromagnetic wave measurement while drilling

Abstract

The utility model discloses an insulating antenna for electromagnetic wave measurement while drilling, which comprises an upper drill collar joint, a middle drill collar joint and a lower drill collar joint, the upper drill collar joint is of a structure with a female buckle at the upper end and a male buckle at the lower end, the middle drill collar joint is of a structure with female buckles at the two ends, and the lower drill collar joint is of a structure with male buckles at the two ends. Female buckles at the two ends of the middle drill collar joint are in threaded connection with a male buckle at the lower end of the upper drill collar joint and a male buckle at the upper end of the lower drill collar joint respectively, the male buckle at the lower end of the upper drill collar joint and the male buckle at the upper end of the lower drill collar joint are the same in structure and each comprise an inner shoulder at the front end and an outer shoulder at the rear end, and insulating layers are arranged on the inner shoulders, the outer shoulders and the male buckles. An insulating washer is arranged between the inner shoulder and the female buckle of the middle drill collar joint; and an adjusting washer is arranged between the outer shoulder and the female buckle of the middle drill collar joint. The insulated antenna disclosed by the utility model is simple in structural process, large in insulation value, long in transmission distance and high in reliability, and can be widely applied to an electromagnetic wave measurement-while-drilling system, an electromagnetic wave relay-while-drilling system and a wireless short transmission-while-drilling system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil and gas drilling, and particularly relates to an insulating antenna for electromagnetic wave measurement while drilling, belonging to electromagnetic wave measurement while drilling instruments. BACKGROUND

[0002] In the exploration and development of oil and gas, wireless measurement while drilling instruments can monitor and control the well trajectory in real time, continuously and accurately, and have become the most commonly used measurement means in the current drilling process. Wireless measurement while drilling instruments are mainly divided into mud pulse transmission and electromagnetic wave transmission according to different transmission modes.

[0003] Mud pulse measurement while drilling instruments rely on the pressure pulse change of drilling fluid to transmit information, and the transmission depth is relatively deep, but the disadvantages are also obvious. The mud pulse measurement while drilling instruments have high requirements for drilling fluid, and cannot be used normally in underbalanced wells, air drilling and coalbed methane drilling.

[0004] Electromagnetic wave measurement while drilling instruments rely on electromagnetic wave transmission along the drill string and the formation to transmit information, and have no special requirements for drilling fluid. The electromagnetic wave transmission rate is very fast, and the efficiency is higher than that of mud pulse transmission. In addition to being applied in ordinary drilling, electromagnetic wave measurement while drilling instruments are also widely used in underbalanced wells, air drilling and coalbed methane drilling. However, electromagnetic wave transmission is greatly affected by the formation, the signal attenuates quickly, and the anti-noise ability is poor, resulting in a general transmission depth and less application in deep well drilling.

[0005] As a key component of electromagnetic wave transmission, the insulating antenna functions as an insulating medium, which divides the drill string into two sections and constitutes two electrodes for electromagnetic wave transmission. Therefore, the performance of the insulating antenna directly determines the transmission depth and reliability of the electromagnetic wave measurement while drilling instrument. The insulating antenna can also be used as a transceiving antenna of the electromagnetic wave repeater, which can greatly improve the electromagnetic wave transmission depth. At the same time, the insulating antenna connects the upper and lower drill strings and has to withstand high pressure, torque and bending moment and other adverse working conditions in the well. Therefore, the insulating antenna is a key technology of the electromagnetic wave measurement while drilling instrument.

[0006] The traditional insulating antenna for electromagnetic wave measurement while drilling is generally composed of two drill collar joints or three drill collar joints, and an insulating layer is sprayed on the thread and the inner and outer cylindrical surfaces of the joint to achieve the insulating effect between the joints. In the complex downhole conditions, the insulating antenna has to withstand huge complex alternating stress. The insulating layer at the thread will be damaged due to fatigue under long-term alternating stress, and the insulating layer on the inner and outer cylindrical surfaces will also be damaged due to long-term friction with the well wall and erosion by mud, resulting in damage to the insulating antenna and affecting the drilling operation.

[0007] Utility model patent CN201320268809.3 discloses a kind of dipole antenna, by upper and lower drill collar joint, non-metallic material is attached on the thread and shoulder of their connecting place to form insulation layer, once the thread insulation layer fails, antenna cannot work.This insulation antenna of single thread insulation, reliability is low.

[0008] Utility model patent CN201520955929.X discloses a kind of electromagnetic wave measurement while drilling reinforced insulation antenna short section, by upper, middle and lower drill collar joint, insulation adhesive layer is arranged on the thread and shoulder of the connecting place of upper, middle and middle lower two joints, in addition, insulation adhesive layer is also arranged on the inner and outer circumference of drill collar joint.This insulation antenna indeed improves reliability to some extent, but overall process is complex, the insulation layer of inner and outer circumference of drill collar joint is not protected, not wear-resistant and difficult to maintain. SUMMARY

[0009] The technical problem to be solved by the present application is to provide an electromagnetic wave measurement while drilling insulation antenna with simple structure and process, good insulation effect and high reliability, which can work in complex downhole conditions for a long time, is durable and easy to maintain.

[0010] The application adopts the following technical solutions:

[0011] An electromagnetic wave measurement while drilling insulation antenna, improved in that it comprises an upper drill collar joint, an intermediate drill collar joint and a lower drill collar joint, the upper drill collar joint has a female end on the upper end and a male end on the lower end, the intermediate drill collar joint has a female end on each end, and the lower drill collar joint has a male end on each end, the female ends of the intermediate drill collar joint are threadedly connected to the male end of the upper drill collar joint and the male end of the lower drill collar joint, respectively, the male ends of the upper drill collar joint and the lower drill collar joint are identical in structure, each comprising an inner shoulder at the front end and an outer shoulder at the rear end, and an insulation layer is arranged on the inner and outer shoulders and the male ends, an insulation washer is arranged between the inner shoulder and the female end of the intermediate drill collar joint, and an adjusting washer is arranged between the outer shoulder and the female end of the intermediate drill collar joint.

[0012] Further, the upper end of the upper drill collar joint has a standard thread, and the lower end has a special taper thread; the upper end of the lower drill collar joint has a special taper thread, and the lower end has a standard thread.

[0013] Further, the insulation layer is formed by spraying a certain thickness of non-metallic material at high temperature.

[0014] Further, the insulation washer is a non-metallic ring, and the adjusting washer is a metal ring.

[0015] Further, an outer annular groove is arranged on the circumference of the outer wall of the adjacent parts of the upper drill collar joint, the middle drill collar joint and the lower drill collar joint, and a protective outer cylinder is arranged on the outer annular groove between the middle drill collar joint and the upper drill collar joint and the lower drill collar joint.

[0016] Further, the protective outer cylinder is a non-metallic cylinder, and two O-shaped rubber sealing rings are arranged on the lower surface of the protective outer cylinder, one between the protective outer cylinder and the outer wall of the middle drill collar joint, and the other between the protective outer cylinder and the outer wall of the upper drill collar joint or the lower drill collar joint.

[0017] Further, an annular boss is arranged on the outer side of the outer annular groove of the upper drill collar joint and the lower drill collar joint, and two annular bosses are arranged on the inner side of the outer annular groove of the middle drill collar joint.

[0018] Further, a plurality of bosses are arranged on the end surface of the protective outer cylinder on the side of the middle drill collar joint, and grooves corresponding to the positions and shapes of the bosses are arranged on the outer wall of the middle drill collar joint.

[0019] Further, an inner annular groove is arranged on the circumference of the inner wall of the adjacent parts of the upper drill collar joint, the middle drill collar joint and the lower drill collar joint, and a protective inner cylinder is arranged on the inner annular groove between the middle drill collar joint and the upper drill collar joint and the lower drill collar joint.

[0020] Further, the protective inner cylinder is a non-metallic cylinder, and two O-shaped rubber sealing rings are arranged on the lower surface of the protective inner cylinder, one between the protective inner cylinder and the inner wall of the middle drill collar joint, and the other between the protective inner cylinder and the inner wall of the upper drill collar joint or the lower drill collar joint.

[0021] The beneficial effects of the present application are:

[0022] The female buckle of the intermediate drill collar joint of the disclosed insulated antenna is connected with inner and outer double-shoulder structures, which can withstand higher torque and bending moment; a certain thickness of high-strength non-metallic material is sprayed on the inner and outer shoulders and the female buckle by a special process, thereby forming two inner and outer insulation layers between the three drill collar joints, greatly improving the insulation value and reliability; the inner and outer insulation layers are absolutely sealed by high-strength non-metallic protective inner and outer cylinders, and the inner and outer insulation layers are protected from erosion by downhole mud and external damage, making the insulation performance more stable, and the protective inner and outer cylinders have higher material strength than the insulation layers, with the characteristics of long-lasting and convenient replacement.

[0023] The disclosed insulated antenna has simple structure and process, high insulation value, long transmission distance and high reliability, and can be widely applied in electromagnetic wave while-drilling measurement systems, electromagnetic wave while-drilling relay systems and while-drilling wireless short transmission systems. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a front sectional view of the insulated antenna disclosed by the present application;

[0025] Figure 2 is a front sectional view of the upper drill collar joint disclosed by the present application;

[0026] Figure 3 is a front sectional view of the lower drill collar joint disclosed by the present application;

[0027] Figure 4 is a front sectional view of the protective outer cylinder disclosed by the present application;

[0028] Figure 5 is a structural schematic view of the intermediate drill collar joint disclosed by the present application.

[0029] Reference signs: 1-upper drill collar joint, 2-intermediate drill collar joint, 3-lower drill collar joint, 4-adjusting washer, 5-insulating washer, 6-protective outer cylinder, 7-protective inner cylinder, 8-inner shoulder, 9-outer shoulder, 10- boss, 11-annular boss, 12-groove. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0031] Example 1 discloses an electromagnetic wave MWD insulated antenna, which is installed in the middle of the drill string, insulates the drill string from the middle, and forms two electrodes for electromagnetic wave transmission at both ends. As shown in Figure 1 , the upper drill collar joint 1, the intermediate drill collar joint 2 and the lower drill collar joint 3 are made of high-strength corrosion-resistant metal materials, the upper drill collar joint has an upper female thread and a lower male thread structure, the intermediate drill collar joint has two female thread structures at both ends, and the lower drill collar joint has two male thread structures at both ends. The two female threads at both ends of the intermediate drill collar joint are threadedly connected with the lower male thread of the upper drill collar joint and the upper male thread of the lower drill collar joint, respectively, as shown in Figure 2 , the lower male thread of the upper drill collar joint and the upper male thread of the lower drill collar joint have the same structure, both including an inner shoulder 8 at the front end and an outer shoulder 9 at the rear end. The inner shoulder is a secondary shoulder that bears secondary stress, and the outer shoulder is a primary shoulder that bears primary stress. The double shoulder structure can effectively optimize the uneven stress problem of the thread, improve the torsional strength, and increase the reliability of the insulation. An insulation layer is arranged on the inner and outer shoulders and the male threads (at the position of the dashed line in Figure 2 , 3), thereby forming two inner and outer insulation layers between the three drill collar joints. An insulating washer 5 is installed between the inner shoulder and the female thread of the intermediate drill collar joint, and an adjusting washer 4 is installed between the outer shoulder and the female thread of the intermediate drill collar joint.

[0032] The upper female thread of the upper drill collar connector is a standard thread, and the lower male thread is a specially made tapered thread; the upper male thread of the lower drill collar connector is a specially made tapered thread, and the lower male thread is a standard thread. The female threads at both ends of the intermediate drill collar connector adopt a large arc design at the tooth tip, which, when matched with the specially made tapered thread of the aforementioned male thread, can effectively reduce the pressure damage to the insulation layer at the connection between the female thread and the male thread under high torque and high bending moment conditions.

[0033] An insulating layer is formed by spraying a certain thickness of high-strength non-metallic material at high temperature using a special process.

[0034] The insulating washer is a high-strength non-metallic ring, which increases the reliability of the insulation; the adjusting washer is a high-strength metal ring, and by reasonably selecting the width of the adjusting washer, the force distribution of the thread teeth and the outer shoulder can be balanced, and the influence caused by the inconsistent thickness of the sprayed insulation layer can be compensated.

[0035] An outer annular groove is provided on the circumference of the outer wall of the adjacent parts (connection points) of the upper drill collar joint, the intermediate drill collar joint, and the lower drill collar joint, and a protective outer cylinder 6 is installed on the outer annular groove between the intermediate drill collar joint and the upper and lower drill collar joints.

[0036] The protective outer cylinder is a high-strength, highly wear-resistant non-metallic cylinder, durable and effectively protecting the outer insulation layer. The protective outer cylinder can be directly replaced after long-term use and damage, making maintenance convenient.

[0037] Below the protective outer cylinder are two O-ring rubber seals. One is located between the outer wall of the protective outer cylinder and the middle drill collar joint, and the other is located between the outer wall of the protective outer cylinder and the upper or lower drill collar joint. That is, they are located on both sides of the outer insulation layer of the upper and lower drill collar joints, respectively. This can prevent downhole mud from entering the outer insulation layer and ensure the stability of the insulation value.

[0038] An annular boss 11 is provided on the outer side of the outer annular groove of both the upper and lower drill collar joints; two annular bosses are provided on the inner side of the outer annular groove of the middle drill collar joint. Positioning the annular bosses on both sides of the protective outer cylinder can effectively reduce the friction between the well wall and the protective outer cylinder and the scouring of the protective outer cylinder by the mud, thereby improving the service life of the protective outer cylinder.

[0039] like Figure 4 As shown in Figure 5, several bosses 10 evenly distributed along the circumference are provided on the end face of the protective outer cylinder located on the side of the intermediate drill collar joint. Grooves 12 corresponding to the positions and shapes of the bosses are provided on the outer wall of the intermediate drill collar joint. After the bosses are inserted into the grooves, they can prevent the protective outer cylinder from rotating when rubbed by the well wall, making the protective outer cylinder more durable.

[0040] In the adjacent parts (connection) of the upper, middle and lower drill collar joints, an inner annular groove is arranged on the circumference of the inner wall, and a protective inner cylinder 7 is arranged in the inner annular groove between the middle drill collar joint and the upper and lower drill collar joints.

[0041] The protective inner cylinder is a high-strength and high-wear-resistance non-metal cylinder, which is durable and can effectively protect the inner insulation layer. The protective inner cylinder can be directly replaced after long-term use and damage, and the maintenance is convenient.

[0042] There are two O-shaped rubber sealing rings under the protective inner cylinder, one of which is located between the protective inner cylinder and the inner wall of the middle drill collar joint, and the other is located between the protective inner cylinder and the inner wall of the upper or lower drill collar joint. That is, it is located on both sides of the inner insulation layer of the upper and lower drill collar joints, which can prevent the mud from entering the inner insulation layer and ensure the stability of the insulation value.

Claims

1. An insulated antenna for electromagnetic wave measurement while drilling, characterized in that: The system includes an upper drill collar connector, an intermediate drill collar connector, and a lower drill collar connector. The upper drill collar connector has a female thread at the top and a male thread at the bottom. The intermediate drill collar connector has female threads at both ends, and the lower drill collar connector has male threads at both ends. The female threads at both ends of the intermediate drill collar connector are threaded to the lower male thread of the upper drill collar connector and the upper male thread of the lower drill collar connector, respectively. The lower male thread of the upper drill collar connector and the upper male thread of the lower drill collar connector have the same structure, both including an inner shoulder at the front end and an outer shoulder at the rear end. Insulating layers are provided on the inner and outer shoulders and the male threads. An insulating washer is installed between the inner shoulder and the female thread of the intermediate drill collar connector, and an adjusting washer is installed between the outer shoulder and the female thread of the intermediate drill collar connector.

2. The insulated antenna for electromagnetic wave measurement while drilling according to claim 1, characterized in that: The upper female thread of the upper drill collar connector is a standard thread, and the lower male thread is a special tapered thread; the upper male thread of the lower drill collar connector is a special tapered thread, and the lower male thread is a standard thread.

3. The insulated antenna for electromagnetic wave measurement while drilling according to claim 1, characterized in that: An insulating layer is formed by spraying a non-metallic material of a certain thickness at high temperature.

4. The insulated antenna for electromagnetic wave measurement while drilling according to claim 1, characterized in that: The insulating washer is a non-metallic ring; the adjusting washer is a metallic ring.

5. The insulated antenna for electromagnetic wave measurement while drilling according to claim 1, characterized in that: An outer annular groove is provided on the circumference of the outer wall of the adjacent parts of the upper drill collar joint, the intermediate drill collar joint, and the lower drill collar joint. A protective outer cylinder is installed on the outer annular groove between the intermediate drill collar joint and the upper and lower drill collar joints.

6. The insulated antenna for electromagnetic wave measurement while drilling according to claim 5, characterized in that: The protective outer cylinder is a non-metallic cylinder; there are two O-ring rubber seals at the bottom of the protective outer cylinder, one between the outer wall of the protective outer cylinder and the middle drill collar joint, and the other between the outer wall of the protective outer cylinder and the upper or lower drill collar joint.

7. The insulated antenna for electromagnetic wave measurement while drilling according to claim 5, characterized in that: An annular boss is provided on the outer side of the outer annular groove of the upper and lower drill collar joints; two annular bosses are provided on the inner side of the outer annular groove of the middle drill collar joint.

8. The insulated antenna for electromagnetic wave measurement while drilling according to claim 5, characterized in that: Several bosses are evenly distributed in the circumferential direction on the end face of the protective outer cylinder located on the side of the intermediate drill collar joint, and grooves corresponding to the positions and shapes of the bosses are provided on the outer wall of the intermediate drill collar joint.

9. The insulated antenna for electromagnetic wave measurement while drilling according to claim 1, characterized in that: Inner annular grooves are provided on the circumference of the inner walls of adjacent parts of the upper drill collar joint, the intermediate drill collar joint, and the lower drill collar joint, and a protective inner cylinder is installed on the inner annular groove between the intermediate drill collar joint and the upper and lower drill collar joints.

10. The insulated antenna for electromagnetic wave measurement while drilling according to claim 9, characterized in that: The protective inner cylinder is a non-metallic cylinder; there are two O-ring rubber seals at the bottom of the protective inner cylinder, one between the inner wall of the protective inner cylinder and the middle drill collar joint, and the other between the inner wall of the protective inner cylinder and the upper or lower drill collar joint.

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