CN106609667B

CN106609667B - Electrode in electromagnetic measurement while drilling system

Info

Publication number: CN106609667B
Application number: CN201510690165.0A
Authority: CN
Inventors: 宋朝晖; 陈晓晖; 王立双; 高炳堂; 杨春国; 胡越发; 孙连环
Original assignee: China Petroleum and Chemical Corp; Sinopec Research Institute of Petroleum Engineering
Current assignee: China Petroleum and Chemical Corp; Sinopec Research Institute of Petroleum Engineering
Priority date: 2015-10-22
Filing date: 2015-10-22
Publication date: 2020-07-31
Anticipated expiration: 2035-10-22
Also published as: CN106609667A

Abstract

The invention provides an electrode in an electromagnetic measurement while drilling system, which is used for conducting a coupling assembly in an antenna with an antenna shell. The electrode comprises a plurality of elastic pieces and positioning cylinders for fixing the upper end and the lower end of the elastic pieces, the elastic pieces are arranged at intervals in the circumferential direction of the positioning cylinders, and the middle parts of the elastic pieces protrude outwards relative to the two ends. When the positioning cylinder is sleeved on the coupling assembly, the protruding part of the elastic piece is contacted with the inner wall of the antenna shell. The electrode is formed independently relative to the coupling assembly in the antenna and the antenna shell, can be flexibly disassembled and replaced according to specific requirements, and is convenient to maintain and long in service life.

Description

Electrode in electromagnetic measurement while drilling system

Technical Field

The invention relates to the technical field of petroleum, mines and geological exploration, in particular to an electrode in an electromagnetic measurement while drilling system.

Background

As is well known, an electromagnetic measurement while drilling system can measure underground engineering and geological information in real time during the drilling process, and then send the underground information to the ground in real time by using low-frequency electromagnetic waves. The material and structure of the antenna used for transmitting the electromagnetic signals have a great influence on the performance of the generated electromagnetic signals. At present, one of the widely used antennas is a coupling antenna, which has the advantages of simple structure, easy processing, high strength of the transmitted electromagnetic signal, stable excitation effect, and the like.

The coupled antenna is arranged on the drill collar, the drill collar is divided into an upper pole and a lower pole by a section of insulating section, and the underground transmitter applies two paths of electric signals to two ends of the antenna, so that the corresponding electromagnetic signals can be generated by excitation and sent to the ground. The coupled antenna is composed of a shell and an internal coupling component, and external insulation and internal insulation are respectively realized. The internal coupling component is made of a metal conductor and is divided into an upper pole and a lower pole by a section of solid insulation section. The upper and lower poles of the internal coupling assembly need to be in full contact with the two stages of the shell to successfully excite and generate the electromagnetic signal. Because the internal coupling assembly and underground instruments such as an underground transmitter, a battery, a measuring short joint and the like are fixedly hoisted in the antenna shell in a seat key mode, one pole of the internal coupling assembly is communicated by the contact of the seat key and the shell, and the other pole of the internal coupling assembly needs to be communicated by the contact of measures and the shell.

The contact modes of the internal coupling component of the current mainstream antenna and the shell comprise the following three modes: (1) a groove is formed below the internal coupling component, and the spring piece is fixed by screws to be in contact with the shell. The spring piece in the method has small contact force and is not impact-resistant and easy to damage by erosion. (2) A lateral screw extends from the inner coupling component, and the screw is screwed to realize contact conduction with the shell. Using the above method, the tool needs to be retightened at the wellhead each time it is run into the well. In addition, the drilling fluid tends to erode the housing in the direction of the screw, creating a puncture at this point, compromising drilling safety. (3) A claw-type metal sheet or a bent arc-shaped metal sheet is cast on the inner coupling component, and is pressed by means of tension and the shell. However, such overhanging metal sheets are easily damaged by erosion by the slurry. In addition, the integral structure causes the metal sheet to be undetachable, and once the metal sheet is damaged, the metal sheet must be completely replaced, so that the use cost is high.

Disclosure of Invention

In order to solve some or all of the technical characteristics, the invention provides an electrode in an electromagnetic measurement while drilling system, which is used for conducting a coupling assembly inside an antenna with an antenna shell.

The electrode comprises a plurality of elastic pieces and positioning cylinders for fixing the upper end and the lower end of the elastic pieces, the elastic pieces are arranged at intervals in the circumferential direction of the positioning cylinders, and the middle parts of the elastic pieces protrude outwards relative to the two ends. When the positioning cylinder is sleeved on the coupling assembly, the protruding part of the elastic piece is contacted with the inner wall of the antenna shell. Preferably, the positioning cylinder comprises an upper positioning cylinder and a lower positioning cylinder which are spaced apart. The elastic pieces are three arched metal sheets, the upper ends of the elastic pieces are fixed on the upper positioning barrel, the lower ends of the elastic pieces are fixed on the lower positioning barrel, and the circumferential interval between every two adjacent elastic pieces is 120 degrees.

In this case, the electrode is formed separately from the antenna housing with respect to the coupling assembly inside the antenna, allowing flexible removal and replacement of the position according to specific needs. The independently formed electrode can effectively avoid the problem that the current repeatedly stimulates the same position of the internal coupling component to cause electric corrosion to damage an instrument; on the other hand, the multifunctional key can be used for instruments with upper seat keys and lower seat keys and has universality. For example, when the seat key is on top, the electrodes are mounted below; when the seat is keyed down, the electrode is mounted above.

Further, the ends of the positioning cylinders are each configured with a 20 ° chamfer. Thus, the drilling fluid only erodes the positioning barrel and does not erode the body.

Further, the inner end of the positioning cylinder is configured with a slope inclined toward the center of the elastic member. Therefore, the condition that the instrument body at the junction of the spring piece and the positioning barrel is eroded by the drilling fluid and damaged due to the vortex effect of the drilling fluid when the instrument works underground can be avoided.

Furthermore, the contact of the convex part of the elastic piece and the inner wall of the antenna shell is in interference fit, and the interference magnitude is 2mm-3.5 mm. Therefore, the elastic piece and the antenna shell can be ensured to be in good electric contact, and the problem that the instrument is difficult to enter the well due to overlarge friction force between the elastic piece and the antenna shell can be avoided.

In this case, when the interference between the elastic member and the antenna housing is 2mm-3.5mm, the corresponding contact friction force between the elastic member and the antenna housing is 110 and 180N. The friction force range is an optimal value determined by correcting experimental data on the basis of multiple times of field experimental data by considering the influence of construction field factors, instrument setting conditions and the gravity of the instrument.

Furthermore, the elastic piece is fixed on the positioning cylinders at the upper end and the lower end of the electrode in a riveting mode. Preferably, a riveting screw hole is formed in the positioning cylinder, and a riveting screw capable of being matched with the riveting screw hole is formed in the elastic piece. Therefore, the firmness of connection between the elastic part and the positioning cylinder can be enhanced, and the situation that the elastic part is eroded by drilling fluid to cause electrode damage is avoided.

Furthermore, the elastic piece is cast in an integrated molding mode. Therefore, the bending radian of the elastic pieces can be consistent, and the elastic pieces can be uniformly contacted with the inner wall of the antenna shell.

Furthermore, the elastic part and the positioning cylinder are both prepared from non-magnetic metal materials, and the non-magnetic metal materials comprise beryllium bronze. The antenna shell is prepared by adopting a non-magnetic drill collar with a standard aperture. In this case, the prepared electrode has high strength, and can not generate electric spark, thereby causing no damage to the circuit of the instrument.

The invention has the advantages that: (1) the electrode is arranged on the internal coupling assembly of the antenna, the position can be flexibly disassembled and replaced according to the requirement, the maintenance is convenient, and the use cost is low. (2) The electrode is designed by adopting a special structure, so that the electric contact performance is good, and the service life is long; and the clamping stagnation phenomenon is avoided when the automobile is driven in. (3) The electrode has simple structure and high reliability, is easy to realize under the domestic prior art level and the processing technology, and has good use effect proved by field construction application.

Drawings

The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:

FIG. 1 is a schematic structural diagram of an electrode according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view A-A of FIG. 1;

fig. 3 is a schematic view illustrating interference between the elastic member of the electrode and the antenna housing according to the embodiment of the invention;

fig. 4 is a schematic view of a measuring and testing tool for interference between an elastic member of an electrode and an antenna housing according to an embodiment of the present invention.

In the drawings, like parts are provided with like reference numerals. The drawings are not to scale.

Detailed Description

The invention will be further explained with reference to the drawings.

As shown in fig. 1 to 3, an electrode 100 in an electromagnetic measurement while drilling system is used for conducting a coupling component 7 inside an antenna with an antenna housing 8. The electrode 100 includes a plurality of elastic members 3 and a positioning cylinder 2 fixing upper and lower ends of the elastic members. As shown in fig. 2, a plurality of elastic members 3 are provided at intervals in the circumferential direction of the positioning cylinder 2. The middle parts of the elastic members 3 protrude outward with respect to the both ends, and as shown in fig. 3, when the positioning cylinder 2 is fitted over the coupling unit 7, the protruding parts of the elastic members 3 contact the inner wall of the antenna housing 8.

In one embodiment of the present invention, the electrode 100 is made of a non-magnetic, high-strength, non-sparking metallic conductor material, such as beryllium bronze. The electrode 100 comprises three elastic members 3 which are fixed up and down on the positioning cylinder 2 and are circumferentially spaced by 120 degrees. The electrode 100 is in close contact with the inner wall of the antenna housing 8 by means of a contact force generated by elastic deformation of the plurality of elastic members 3, thereby communicating the coupling member 7 with the antenna housing 8. Preferably, the elastic member 3 is an arcuate metal sheet. The arched metal sheets are cast in an integrated mode, so that the three arched metal sheets are ensured to be consistent in bending radian, and can be uniformly and tightly contacted with the inner wall of the antenna shell 8. In this case, since the electrode 100 is designed to be completely independent, it can be directly mounted on the cylindrical internal coupling assembly 7 during use, and the electrode 100 can be fixed in a specific position by using a tightening screw, and can be flexibly disassembled and replaced as required. In this way, it is avoided that the current on the electrode 100 repeatedly stimulates the same site of the internal coupling component 7, causing galvanic corrosion, so as to cause damage to the instrument.

In one embodiment of the present invention, as shown in fig. 1, the arched metal sheets are fixed to the positioning cylinders 2 at the upper and lower ends of the electrode 100 by riveting. Preferably, a riveting screw hole 4 is formed in the positioning cylinder 2, and a riveting screw 1 capable of being matched with the riveting screw hole 4 is arranged on the elastic member 3. Therefore, the firmness of connection between the arched metal sheet and the positioning cylinder 2 can be enhanced, and the condition that the electrode is damaged due to the fact that the electrode is eroded by drilling fluid in the using process is effectively avoided.

In an embodiment of the invention, in order to avoid the eddy effect of the drilling fluid causing the erosion damage of the boundary between the arched metal sheet and the positioning cylinder 2 when the instrument works in the well, as shown in fig. 1, the positioning cylinder 2 is provided with a raised part 5 at the inner side and is chamfered 6 by 20 degrees. Thus, the drilling fluid only erodes the positioning cylinder 2, but does not erode the body; the arc-shaped metal sheet is fixed by riveting, the electrode is processed by selecting high-hardness materials, and the like, so that the service life of the electrode 100 can be greatly prolonged, and the requirements of field use are met.

In order to ensure the electrical contact performance of the electrode 100, the contact force between the arcuate metal sheet and the inner wall of the antenna housing 8 should be determined within a proper range, because too small a contact force tends to result in poor electrical contact, but too large a contact force tends to make it difficult to run the instrument downhole. The magnitude of the contact force depends on the interference magnitude a of the interference fit between the elastic member 3 and the inner wall of the antenna housing 8, and as shown in fig. 3, the interference magnitude a is the variation of the arcuate metal sheet 3 in the direction perpendicular to the inner wall of the antenna housing 8 relative to the arcuate metal sheet 9 that is compressed and deformed after being inserted into the instrument. The larger A, the greater the contact force generated, and the greater the friction between the elastic member 3 of the electrode 100 and the inner wall of the antenna housing 8 when the instrument is set in.

In order to determine the size of the interference magnitude A, the invention designs a test tool to measure the friction force F generated by the interference on the inner wall of the shell, as shown in FIG. 4. After the internal coupling assembly 7 and the electrode 100 are connected and fixed, the internal coupling assembly and the pressing tool 12 are assembled to form a test instrument string. The pressing tool is of a T-shaped structure, the connector is matched with the connector of the internal coupling assembly 7 and screwed down by threads, and the upper end of the pressing tool is provided with a pressure gauge 11. A standard-aperture non-magnetic drill collar 13 with the length of 1m is taken as a simulation drilling tool, a test instrument string penetrates through the drill collar 13 in the middle, the reading of a pressure gauge 11 is observed, and then the maximum value is taken, namely the friction force F generated under the interference magnitude A condition. Considering that when the instrument is taken off and put down in the field drilling process, the matching surfaces of the electrode 100 and the inner wall of the antenna shell 8 are provided with the drilling fluid solid-phase particles and rock debris, so that the friction force generated when the instrument is put down is larger than the experimental data obtained in the experiment. After the influence of construction site factors, the setting working condition and the self weight of the instrument is considered, experimental data are corrected on the basis of multiple on-site test data, and finally the friction force F is determined to be an optimal value when the friction force F is in the range of 110N to 180N. And finally, according to the test tool, the optimal interference A of the electrodes made of different materials can be determined by reverse estimation.

In an embodiment of the invention, interference magnitude tests are performed on the beryllium bronze electrode by using the test tool provided in the invention, and the friction forces generated by different interference magnitudes are shown in table 1. Considering the self weight of the instrument and the working condition of running in, according to the standard that the friction force F provided after actual use and correction is an optimal value in the range of 110N to 180N, the optimal value is determined when the interference A is 2mm-3.5 mm.

TABLE 1 relationship data between interference and friction of beryllium bronze electrodes

Interference magnitude A/mm	Friction force (N)	Whether or not stuck
			1-1.5	60	Whether or not
2-2.5	110	Whether or not
			3-3.5	180	Whether or not
4-4.5	260	Whether or not
			5-5.5	350	Whether or not

In summary, the electrode device according to the present invention can be installed in a coupled antenna, and when the electrode device is used, the drill, the drilling tool assembly and the coupled antenna can be connected in sequence to form a tool string. The electrode of the invention has simple structure and high reliability and is easy to realize under the domestic prior art and processing conditions. The electromagnetic measurement while drilling system using the electrode provided by the invention has stable work and continuous data, and the continuous use time of the electrode can exceed 200 hours.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An electrode in an electromagnetic measurement while drilling system is used for communicating a coupling assembly in an antenna with an antenna shell and is characterized by comprising a plurality of elastic pieces and positioning cylinders for fixing the upper end and the lower end of each elastic piece;

the elastic pieces are arranged at intervals along the circumferential direction of the positioning cylinder;

the middle parts of the elastic pieces are outwards protruded relative to the two ends;

the positioning cylinder is of a cylindrical structure, when the positioning cylinder is sleeved on the coupling assembly, the protruding part of the elastic piece is in contact with the inner wall of the antenna shell, and the electrode is sleeved on the coupling assembly and can be detached and replaced;

the positioning cylinder comprises an upper positioning cylinder and a lower positioning cylinder which are spaced apart, the upper end of the elastic part is fixed on the upper positioning cylinder, and the lower end of the elastic part is fixed on the lower positioning cylinder;

the elastic piece is fixed on the positioning cylinders at the upper end and the lower end of the electrode in a riveting mode.

2. The electrode of claim 1,

the elastic piece is an arched metal sheet;

the arch-shaped convex part of the elastic piece is positioned between the upper positioning cylinder and the lower positioning cylinder.

3. The electrode of claim 2, wherein three of the arcuate metal sheets are spaced apart in a circumferential direction of the positioning cylinder, and adjacent two of the arcuate metal sheets are circumferentially spaced apart by 120 °.

4. The electrode as claimed in claim 1, wherein the inner end of the positioning cylinder is configured with a slope inclined toward the center of the elastic member, and both ends of the positioning cylinder are configured with 20 ° chamfers.

5. The electrode of claim 1, wherein the contact of the protruding portion of the elastic member with the inner wall of the antenna housing is an interference fit.

6. The electrode of claim 5, wherein the interference fit has an interference of 2mm to 3.5 mm.

7. The electrode according to claim 1, wherein a rivet screw hole is provided in the positioning cylinder, and a rivet screw capable of being engaged with the rivet screw hole is provided in the elastic member.

8. The electrode of claim 1, wherein the resilient member is molded as a single piece.

9. The electrode of claim 1, wherein the resilient member and the positioning cylinder are both made of a non-magnetic metal material, and the non-magnetic metal material comprises beryllium bronze.