While-drilling electromagnetic wave foresight distance detection instrument based on electric dipole antenna

Abstract

The invention discloses a while-drilling electromagnetic wave foresight remote detection instrument based on an electric dipole antenna, which adopts a signal transmitting short section, is equipped with three spiral winding loop antennas which are respectively responsible for transmitting electromagnetic wave signals in the axial direction and two horizontal directions, and is matched with at least one signal receiving short section, each signal receiving short section comprises three magnetic dipole antenna receiving coils, and each signal receiving short section comprises three magnetic dipole antenna receiving coils. The sensor is used for capturing magnetic field signals reflected by strata. The short energy can be freely combined, and the transceiving distance can be adjusted, so that different detection requirements can be met. The spiral coil antenna is composed of an annular magnetic core and a copper wire, so that the signal transmission efficiency is enhanced. Compared with the prior art, not only can the stratum behind the drill bit be detected, but also the stratum condition in front of the drill bit can be detected, the farthest detection distance can reach more than 30 meters, and the detection distance of the lateral stratum boundary is also remarkably increased. And due to the application of the low-frequency electromagnetic waves, the long-distance detection efficiency is further improved, the drilling risk is reduced, and the efficiency and safety of petroleum drilling operation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of geophysical exploration or oil drilling technology, and particularly relates to a downhole electromagnetic wave forward long-range detection instrument based on an electric dipole antenna. Background Art

[0002] In the field of oil exploration and development, drilling equipment is an indispensable important tool. To improve the development efficiency of oil and gas wells, it is particularly important to ensure that the drill bit can drill in the direction of the oil and gas-bearing formation. However, the current technology has certain limitations in detecting formation information, especially it is unable to effectively obtain the formation information in front of the drill bit.

[0003] Although traditional downhole azimuth electromagnetic wave instruments can provide information such as resistivity, wave velocity, and porosity of the formation behind the drill bit, these data mainly reflect the formation conditions behind the drill bit and cannot provide information about the formation in front of the drill bit. This asymmetry of information limits the accuracy and safety of drilling to a certain extent.

[0004] Specifically, existing downhole electromagnetic wave instruments usually use magnetic dipole antennas for signal detection. Although this type of antenna can effectively detect the formation information behind the drill bit, due to the limitations of its detection principle and structure, it cannot effectively detect the formation in front of the drill bit. Therefore, during the drilling process, the operator cannot accurately predict the formation conditions ahead, which increases the risk and uncertainty of drilling to a certain extent.

[0005] Therefore, how to effectively detect the formation information in front of the drill bit has become the technical problem to be solved by the present invention. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a downhole electromagnetic wave forward long-range detection instrument based on an electric dipole antenna to solve the problem that traditional downhole azimuth electromagnetic wave instruments cannot detect the formation information in front of the drill bit as described in the above background art.

[0007] To solve the above technical problem, the technical solution adopted by the present invention is as follows:

[0008] A downhole electromagnetic wave forward long-range detection instrument based on an electric dipole antenna, comprising:

[0009] A signal transmitting sub-section, which includes three helical loop antennas, namely an axial transmitting helical loop antenna, a horizontal x-direction transmitting helical loop antenna, and a horizontal y-direction transmitting helical loop antenna, for transmitting electromagnetic wave signals, and the frequency range of the transmitted electromagnetic waves is from 1 kHz to 100 kHz;

[0010] At least one signal receiving sub-section, each receiving sub-section includes three magnetic dipole antenna receiving coils, namely an axial magnetic dipole coil, a horizontal x-direction coil, and a horizontal y-direction coil, which are used to receive the magnetic field signals reflected by the formation;

[0011] The signal transmitting sub-section and the signal receiving sub-section can be freely combined, and the distance between them can be adjusted according to the formation detection requirements within different detection ranges in front of the drill bit.

[0012] As a further solution of the present invention, the helical loop antenna is composed of a circular magnetic core and copper wires wound around the magnetic core, forming an electric dipole.

[0013] As a further solution of the present invention, a combination form of one signal transmitting sub-section and two or more signal receiving sub-sections is adopted to detect the formation resistivity, formation dip angle, and formation boundary in front of the drill bit.

[0014] As a further solution of the present invention, the distances from the front formation boundary and the side formation boundary are represented by the attenuation of data at different frequencies observed by the antennas in the corresponding directions on the two receiving sub-sections.

[0015] As a further solution of the present invention, the instrument is directly connected behind the drill bit to detect the formation information in front of the drill bit, and when the drill bit changes the drilling direction, the instrument changes the drilling direction along with the change of the drill bit direction.

[0016] As a further solution of the present invention, the received observation data is processed by an inversion method to deduce the parameter information of the formation, including formation resistivity and formation boundary.

[0017] As a further solution of the present invention, the helical loop antenna is fixed on the drill collar, and there is no movable space between the coil and the drill collar.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. It can not only provide the formation information behind the drill bit, but also effectively detect the formation conditions in front of the drill bit, thus providing more comprehensive and accurate data support for drilling operations. It solves the problem that the current electromagnetic wave while-drilling azimuth instrument cannot detect the formation boundary in front of the drill bit. Its detection distance can reach more than 30 meters at most, providing unprecedented forward-looking information for oil drilling operations and greatly reducing the uncertainty and risk during the drilling process.

[0020] 2. There is also a significant improvement in the detection distance of the lateral formation boundary. The detection distance of the lateral formation boundary of traditional azimuthal electromagnetic wave logging-while-drilling instruments is about 6 meters. Through the independent design of the transmitting antenna sub-section and the receiving antenna sub-section in the present invention, the transmitting and receiving distance can be freely combined according to the target detection requirements. Usually, a transmitting and receiving distance of 10 meters or even farther is adopted, thereby further enhancing the far-detection ability.

[0021] 3. Flexible adjustment of the transmitting and receiving distance: In the present invention, the transmitting antenna sub-section and the receiving antenna sub-section are independent, and their spacing can be freely combined according to the target detection requirements, which not only improves the flexibility and adaptability of the instrument, but also enables the instrument to be optimally configured according to the specific drilling environment and requirements, thereby improving the detection efficiency and accuracy.

[0022] 4. Low-frequency electromagnetic waves achieve long-distance detection: The electromagnetic wave frequency adopted in the present invention is lower than that of the prior art, which helps to achieve longer-distance detection. Low-frequency electromagnetic waves have less attenuation in the formation and can penetrate deeper formations, thereby providing richer and more accurate formation information.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a schematic diagram of the spiral loop antenna of the present invention.

[0026] Figure 2 It is a schematic structural diagram of the transmitting sub-section of the present invention, where T1 is the axial transmitting spiral loop antenna, T2 is the horizontal x-direction transmitting spiral loop antenna, and T3 is the horizontal y-direction transmitting spiral loop antenna.

[0027] Figure 3 It is a schematic structural diagram of the receiving sub-section of the present invention, where R1 is the axial receiving coil, R2 is the horizontal x-direction receiving coil, and R3 is the horizontal y-direction receiving coil. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Please refer to Figure 1 —3. In the embodiments of the present invention, a forward-looking far-detection instrument for electromagnetic waves while drilling based on an electric dipole antenna includes:

[0030] A signal transmitting sub-section, which includes three helical loop antennas, namely an axial transmitting helical loop antenna, a horizontal x-direction transmitting helical loop antenna, and a horizontal y-direction transmitting helical loop antenna, for transmitting electromagnetic wave signals, and the frequency range of the transmitted electromagnetic waves is from 1 kHz to 100 kHz; three-direction helical loop antennas are designed in this signal transmitting sub-section, and they can transmit electromagnetic wave signals along the axial direction of the drill bit, the horizontal x-direction, and the horizontal y-direction respectively. The frequency range of these signals is between 1 kHz and 100 kHz. Such a design enables the electromagnetic waves to penetrate the formation better and return useful reflection signals.

[0031] At least one signal receiving sub-section, and each receiving sub-section includes three magnetic dipole antenna receiving coils, namely an axial magnetic dipole coil, a horizontal x-direction coil, and a horizontal y-direction coil, for receiving the magnetic field signals reflected by the formation; the receiving sub-section is equipped with receiving coils corresponding to the transmitting antennas, and these coils can capture the magnetic field signals reflected from different directions, providing rich information for subsequent data analysis.

[0032] The signal transmitting sub-section and the signal receiving sub-section can be freely combined, and the distance between them can be adjusted according to the formation detection requirements within different detection ranges in front of the drill bit. This design provides flexibility. According to different detection requirements, the distance between the transmitting and receiving sub-sections can be adjusted to achieve the best detection effect.

[0033] The helical loop antenna is composed of a circular magnetic core and copper wires wound around the magnetic core, forming an electric dipole. The structure of the helical loop antenna includes a circular magnetic core, and the copper wires are closely wound around this magnetic core. This structure enables the antenna to effectively transmit and receive electromagnetic wave signals.

[0034] A combination form of one signal transmitting sub-section and two or more signal receiving sub-sections is used to detect the formation resistivity, formation dip angle, and formation boundary in front of the drill bit. By using multiple receiving sub-sections, the formation information such as formation resistivity, formation dip angle, and formation boundary can be analyzed more accurately, because multiple receiving points can provide more data for comparison and analysis.

[0035] The distances from the front formation boundary and the side formation boundary are represented by the attenuation of data at different frequencies observed by the antennas in the corresponding directions on the two receiving subsections. By analyzing the attenuation of signals at different frequencies on the two receiving subsections, the distances to the formation boundaries can be estimated, which is crucial for decision-making in drilling operations.

[0036] The instrument is directly connected behind the drill bit and is used to detect the formation information in front of the drill bit. When the drill bit changes its drilling direction, the instrument changes its drilling direction along with the drill bit direction. The instrument is designed to closely follow behind the drill bit to ensure real-time acquisition of the formation information in front of the drill bit. In addition, its directional design enables it to turn along with the rotation of the drill bit, always maintaining synchronization with the drill bit.

[0037] The received observation data is processed by an inversion method to derive the parameter information of the formation, including the formation resistivity and the formation boundary. The received data needs to go through a specialized processing method to extract useful formation information. The inversion method is an effective data processing means that can help us derive important parameters such as the resistivity and boundary of the formation.

[0038] The helical loop antenna is fixed on the drill collar, and there is no movable space between the coil and the drill collar. This design ensures the stability of the antenna during drilling, avoiding signal distortion or data errors caused by vibration or movement. The tight fixation between the antenna and the drill collar makes data collection more accurate and reliable.

[0039] Embodiment 1:

[0040] This embodiment provides a specific application of an electromagnetic wave forward-looking long-range detection instrument while drilling based on an electric dipole antenna. The instrument is directly connected behind the drill bit to detect the formation information in front of the drill bit in real time during drilling.

[0041] The signal transmitting subsection of the instrument includes three helical loop antennas, which are respectively responsible for transmitting electromagnetic wave signals in the axial direction, horizontal x direction, and horizontal y direction. The frequency range of these signals is from 1 kHz to 100 kHz, ensuring effective detection of different formation depths. The helical loop antenna consists of a circular magnetic core and copper wires wound around it, forming an electric dipole, and this structure enhances the signal transmitting and receiving capabilities.

[0042] During drilling, the electromagnetic wave signals transmitted by the signal transmitting subsection penetrate the formation and are reflected when encountering formations with different resistivities. These reflected signals are then captured by the receiving coils of the magnetic dipole antennas in the signal receiving subsection. Each receiving subsection also includes receiving coils in three directions, corresponding to the axial direction, horizontal x direction, and horizontal y direction respectively, so as to comprehensively receive the reflected signals from different directions.

[0043] In order to accurately detect the formation information in front of the drill bit, a combination of a signal transmitting sub-section and two signal receiving sub-sections is adopted. This configuration not only improves the detection sensitivity but also can accurately calculate the distances to the formation boundary in front and the formation boundary on the side by comparing the attenuation of different frequency data observed by the antennas in the corresponding directions on the two receiving sub-sections.

[0044] When the drill bit changes its drilling direction, the instrument can flexibly adjust its detection direction to ensure that it always remains consistent with the direction of the drill bit. This flexibility enables the instrument to provide continuous and accurate formation information in complex drilling environments.

[0045] The received observation data is processed by an inversion method to derive detailed parameter information of the formation, including formation resistivity and formation boundaries, etc. This information is of great significance for guiding drilling operations, improving drilling efficiency and safety.

[0046] In addition, the helical loop antenna is firmly fixed on the drill collar to ensure that it will not move or be damaged during the drilling process, thus ensuring the stability and reliability of the detection data.

[0047] Through the application of the above embodiments, the electromagnetic wave forward-looking long-distance detection instrument while drilling of the present invention demonstrates great potential and practical value in the field of oil exploration and development. It can not only provide formation information in front of the drill bit but also guide drilling operations based on this information, improving the accuracy and safety of drilling. The successful implementation of this technical solution provides an effective and practical method for solving the problems proposed in the background technology.

[0048] Embodiment 2:

[0049] In this embodiment, we will describe in detail the practical application of the electromagnetic wave long-distance detection instrument while drilling proposed by the present invention in oil drilling, especially how it realizes the accurate detection of formation information in front of the drill bit through specific sub-section combinations and data processing methods.

[0050] First of all, our instrument includes a signal transmitting sub-section and multiple signal receiving sub-sections. The transmitting sub-section is equipped with three helical loop antennas (i.e., electric dipole antennas), which are respectively responsible for transmitting electromagnetic wave signals in the axial direction, horizontal x direction, and horizontal y direction, with a frequency range from 1 kHz to 100 kHz. These antennas are uniquely designed, consisting of a circular magnetic core and copper wires tightly wound around the magnetic core, forming an efficient electric dipole structure.

[0051] Before drilling operations, a combination of a transmitting sub and two receiving subs may be set according to the characteristics of the target formation. This configuration can provide richer data to more accurately invert formation information. These subs are directly connected behind the drill bit and maintain a fixed combination form throughout the drilling process to ensure data consistency and comparability.

[0052] During the drilling process, the transmitting sub continuously emits electromagnetic wave signals. These signals penetrate the formation and are reflected back when encountering formation boundaries or resistivity changes. The magnetic dipole antenna receiving coils in the receiving subs are responsible for capturing these reflected signals. Importantly, these coils are fixed on the drill collar with no moving space between them, ensuring data stability and accuracy.

[0053] When the drill bit changes the drilling direction, the instrument also flexibly adjusts its direction accordingly to ensure it always remains consistent with the advancing direction of the drill bit. This flexibility enables the instrument to provide accurate formation information in various complex drilling environments.

[0054] The received observation data is processed by advanced inversion methods. This method takes the observation data as input and, through a large number of mathematical calculations, finally derives detailed parameter information of the formation, including formation resistivity, formation boundaries, etc. This information is of crucial significance for guiding drilling operations, optimizing drilling strategies, and improving drilling efficiency and safety.

[0055] Specifically, by comparing the attenuation of different frequency data observed by the antennas in the corresponding directions on the two receiving subs, the distances to the formation boundaries ahead and to the side can be accurately calculated. This quantitative analysis method provides us with valuable formation information, helping us to more accurately predict and evaluate the advancing path of the drill bit and the possible formation conditions encountered.

[0056] Generally speaking, the electromagnetic wave long-range detection instrument while drilling of the present invention achieves precise detection of the formation information in front of the drill bit through a unique sub combination, flexible direction adjustment, and advanced inversion methods. This technical solution demonstrates great application potential and practical value in the field of oil exploration and development.

[0057] Example 3:

[0058] This example will detail the advantages of the electromagnetic wave long-range detection instrument while drilling in detecting side formation boundaries, flexibly adjusting the transceiver distance, and achieving long-range detection using low-frequency electromagnetic waves.

[0059] I. Improvement in the detection distance of side formation boundaries.

[0060] The detection distance of the lateral formation boundary by traditional logging-while-drilling azimuth electromagnetic wave instruments is limited by their antenna design and signal processing technology, usually only about 6 meters. However, through innovative design, the present invention has significantly improved this detection distance.

[0061] Specifically, the transmitting antenna sub-section and the receiving antenna sub-section of the present invention are independently designed, which enables the transmitting and receiving distances to be freely combined according to the target detection requirements. In practical applications, we usually use a transmitting and receiving distance of 10 meters or even farther for detection. This design not only increases the penetration ability of electromagnetic waves but also improves the signal-to-noise ratio of the signal, thereby further enhancing the far-detection ability.

[0062] To verify this, the detection effects at different transmitting and receiving distances were simulated in a laboratory environment. The experimental results show that when the transmitting and receiving distance is increased to 10 meters, the instrument can still clearly detect the presence of the lateral formation boundary, and the signal quality is significantly better than that of traditional instruments. This result fully demonstrates the effectiveness of the present invention in improving the detection distance of the lateral formation boundary.

[0063] II. Flexible adjustment of the transmitting and receiving distance.

[0064] Another significant advantage of the present invention is the flexibility of the transmitting and receiving distance. Since the transmitting antenna sub-section and the receiving antenna sub-section are independent, they can be optimally configured according to the specific drilling environment and requirements. This flexibility enables the instrument to adapt to different drilling scenarios, thereby improving the detection efficiency and accuracy.

[0065] For example, in a complex drilling environment, if more detailed detection data is required, the transmitting and receiving distance can be appropriately reduced to improve the signal resolution and sensitivity. In scenarios where long-distance detection is needed, the transmitting and receiving distance can be increased to achieve detection at a farther distance. This flexible ability to adjust the transmitting and receiving distance makes the present invention have a wider applicability and higher practical value in practical applications.

[0066] III. Low-frequency electromagnetic waves for long-distance detection.

[0067] The electromagnetic wave frequency adopted by the present invention is lower than that of the prior art, which is the key to achieving long-distance detection. Low-frequency electromagnetic waves have less attenuation during propagation in the formation and can penetrate deeper formations, thereby providing richer and more accurate formation information.

[0068] To verify the advantages of low-frequency electromagnetic waves in long-distance detection, a series of field tests were conducted. The test results show that when using low-frequency electromagnetic waves for detection, the signal can penetrate deeper formations, and the attenuation rate is significantly slower than that of high-frequency electromagnetic waves. This means that using low-frequency electromagnetic waves can obtain information about farther formations, thereby improving the detection depth and accuracy.

[0069] In summary, this embodiment specifically demonstrates the beneficial effects of the present invention in terms of improving the detection distance of the lateral formation boundary, flexible adjustment of the transceiver distance, and achieving long-distance detection with low-frequency electromagnetic waves. These advantages make the present invention have higher practical value and wider applicability in practical applications.

[0070] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", "swivel connection", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A forward-looking long-range detection instrument for electromagnetic waves while drilling based on an electric dipole antenna, characterized in that: Include: A signal transmitting short section, which comprises three spiral ring antennas, namely an axial transmitting spiral ring antenna, a horizontal x-direction transmitting spiral ring antenna, and a horizontal y-direction transmitting spiral ring antenna, for transmitting electromagnetic wave signals, wherein the frequency range of the electromagnetic wave transmitted is from 1 kHz to 100 kHz; At least one signal receiving short section, each receiving short section comprises three magnetic dipole antenna receiving coils, namely, an axial magnetic dipole coil, a horizontal x-direction coil, and a horizontal y-direction coil, for receiving magnetic field signals reflected by the formation; The signal transmitting short section and the signal receiving short section can be freely combined, and the distance between them can be adjusted according to the formation detection requirements within different detection ranges in front of the drill bit.

2. The electromagnetic wave forward-looking long-range detection instrument for drilling based on electric dipole antenna according to claim 1, characterized in that: The spiral ring antenna is composed of a circular magnetic core and a copper wire wound on the magnetic core to form an electric dipole.

3. The electromagnetic wave forward-looking long-range detection instrument for drilling based on electric dipole antenna according to claim 1, characterized in that: A combination of a signal transmitting short section and two or more signal receiving short sections is used to detect the formation resistivity, formation dip and formation boundary in front of the drill bit.

4. The electromagnetic wave forward-looking long-range detection instrument for drilling based on electric dipole antenna according to claim 1, characterized in that: The distances from the front stratum boundary and the lateral stratum boundary are expressed according to the attenuation of data of different frequencies observed by antennas in corresponding directions on the two receiving short sections.

5. The electromagnetic wave forward-looking long-range detection instrument for drilling based on electric dipole antenna according to claim 1, characterized in that: The instrument is directly connected to the rear of the drill bit and is used to detect the formation information in front of the drill bit. When the drill bit changes the drilling direction, the instrument changes the drilling direction along with the change of the drill bit direction.

6. The electromagnetic wave forward-looking long-range detection instrument for drilling based on electric dipole antenna according to claim 1, characterized in that: The received observation data are processed by the inversion method to derive the parameter information of the formation, including the formation resistivity and formation boundaries.

7. The electromagnetic wave forward-looking long-range detection instrument for drilling based on electric dipole antenna according to claim 1, characterized in that: The helical coil antenna is fixed on the drill collar, and there is no movable space between the coil and the drill collar.

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