A multi-boundary detection device and method for electromagnetic waves during drilling

Abstract

This invention discloses a multi-boundary detection device and method using electromagnetic waves during drilling, relating to the field of electrical logging technology in oil exploration and development. The device includes a novel six-transmitter, four-receiver multi-boundary detection coil system, providing four resistivity detection modes (RS, RM, RsD, RD) and four source-distance boundary detection modes (GeoN, GeoM, GeoSD, GeoD). This invention constructs multiple detection modes under multiple frequencies and source distances, achieving high-definition multi-boundary detection of formations within 12m around the well. The proposed orthogonal composite antenna effectively increases the proportion of azimuth signals, doubling the detection distance compared to traditional methods, while effectively eliminating dependence on rotary drilling and broadening the instrument's applicability. Furthermore, the azimuth resistivity design allows the instrument to provide resistivity data for each sector for wellbore resistivity imaging and the average resistivity around the well to reflect the overall electrical level of the formation during rotary drilling.

Description

Technical Field

[0001] This invention relates to the field of electrical logging technology for oil exploration and development, and belongs to the category of azimuth electromagnetic wave logging while drilling. In particular, it relates to a multi-boundary detection device and method for electromagnetic waves while drilling. Background Technology

[0002] Azimuth electromagnetic logging while drilling (AWDB) is a crucial tool for geological steering in horizontal wells. By measuring the cross-components of magnetic fields in real time, it enables precise identification and extraction of formation interfaces (such as reservoir top and bottom interfaces and faults). These instruments typically employ tilted antenna designs with a maximum source distance of less than 2.5 meters, allowing for accurate detection of dual interfaces in the surrounding well area. However, my country's oil and gas reservoirs generally exhibit strong heterogeneity and poor continuity, coupled with complex oil-water relationships and the development of interlayers and thin interbedded layers. This makes it difficult for these instruments to detect the presence of multiple electrical interfaces, resulting in low geological steering accuracy and a low target layer encounter rate. In recent years, both domestically and internationally, increasing the instrument source distance has been widely adopted to improve the detection range. However, limited by relatively fixed antenna designs, the detection capability remains insufficient, and the signal is weak with low imaging resolution.

[0003] Therefore, there is an urgent need to study a drilling electromagnetic wave multi-boundary detection device and method. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that existing logging-while-drilling electromagnetic wave technology cannot accurately detect the formation structure around the well, and to disclose a logging-while-drilling electromagnetic wave multi-boundary detection device and method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A drilling electromagnetic wave multi-boundary detection device includes a novel six-transmitter, four-receiver multi-boundary detection coil system and an instrument drill collar. The novel six-transmitter, four-receiver multi-boundary detection coil system includes: axial receiving antennas R1 and R2, axial transmitting antennas T1, T2, T5, and T6, inclined transmitting antennas T3 and T4, and composite receiving antennas R3 and R4. The midpoint of the axial receiving antennas R1 and R2 is the center of the coil system, and the remaining antennas are symmetrically distributed along the center of the coil system in grooves on the surface of the instrument drill collar. According to the order of distance from the center of the coil system from near to far, the antennas are arranged as follows: axial receiving antennas R1 / R2, axial transmitting antennas T1 / T2, inclined transmitting antennas T3 / T4, axial transmitting antennas T5 / T6, and composite receiving antennas R3 / R4.

[0007] Optionally, the composite receiving antennas R3 and R4 are formed by winding a radial antenna and an axial antenna in opposite directions, and can be implemented in two ways:

[0008] (1) Divide an axial antenna into two semi-circular ring antennas, offset them by a certain distance along the axial direction, and reconnect the corresponding interfaces with the antenna to form a composite antenna with the same number of turns and different areas in the axial and radial parts. The two semi-circular ring axial antennas are different source distances and are symmetrical about the midpoint of the entire antenna structure, which is equivalent to a complete axial antenna in the same position as the radial part.

[0009] (2) Place an axial antenna and a radial antenna horizontally, and connect them in opposite directions through electronic circuitry to form a composite antenna in which the area and number of turns of the axial and radial parts are relatively independent.

[0010] Optionally, the tilted transmitting antenna T3 and the composite receiving antenna R4 are on one working plane, and the tilted transmitting antenna T4 and the composite receiving antenna R3 are on another working plane, with the azimuth angles between the two working planes differing by 90°; the axial transmitting antennas T1, T2, T5, and T6 have no circumferential differences from the axial receiving antennas R1 and R2, and the working planes are not distinguished.

[0011] A second aspect of the present invention provides a method for multi-boundary detection using electromagnetic waves while drilling, employing the above-described device, comprising the following steps:

[0012] A two-layer horizontal layered medium model was established with a well inclination angle of 90°.

[0013] The receiving antenna electromotive force was measured in four resistivity detection modes: RS (Shallow-Resistivity Log), RM (Medium-Resistivity Log), RsD (sub-Deep Resistivity Log), and RD (Deep-Resistivity Log).

[0014] The receiving antenna electromotive force was measured for four source distance boundary detection modes: GeoN (Near-Geosignal Log), GeoM (Medium-Geosignal Log), GeoSD (sub-Distant Geosignal Log), and GeoD (Distant-Geosignal Log).

[0015] Optionally, the four resistivity detection modes, RS, RM, RsD, and RD, are as follows:

[0016] RS resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for axial transmitting antennas T1 and T2 and axial receiving antennas R1 and R2. During detection, the axial transmitting antennas T1 and T2 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , , , These are the coaxial components of the electromotive force at the two source distances, respectively.

[0017] RM resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2. During detection, the tilted transmitting antennas T3 and T4 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , , This is the azimuth angle of the instrument's rotation. , These are the cross components of the electromotive force at the two source distances, respectively;

[0018] RsD resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for axial transmitting antennas T5 and T6 and axial receiving antennas R1 and R2. During detection, axial transmitting antennas T5 and T6 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , ;

[0019] RD resistivity detection mode: A low-to-medium transmission frequency of 400kHz and 100kHz is used, with symmetrical compensation of axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4. During detection, axial transmitting antennas T1 and T2 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , .

[0020] Optionally, under the four resistivity detection modes RS, RM, RsD, and RD, the single-sided amplitude ratio Att and phase difference PS signals are calculated as follows:

[0021] ;

[0022] The average values ​​of the bilateral amplitude ratio and phase difference signals are then input into the apparent resistivity conversion chart to obtain the four levels of apparent resistivity Ra and apparent resistivity Rp around the well, namely shallow-medium-deep-deep.

[0023] Optionally, source distance boundary detection is divided into rotary drilling mode and sliding drilling mode.

[0024] Optionally, in rotary drilling mode, the signal transmission and reception methods for the four source distance boundary detection modes—GeoN, GeoM, GeoSD, and GeoD—are as follows:

[0025] GeoN boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrically compensated tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2, the tilted transmitting antennas T3 and T4 alternately transmit signals during detection. The electromotive force (EMF) at each of the two azimuth angles on a single side is taken as the average of the EMFs of the two receiving antennas, as follows:

[0026] ;

[0027] ;

[0028] In the formula, , These are the coaxial components of the electromotive force at the two source distances, respectively. , These are the cross components of the electromotive force at the two source distances, respectively;

[0029] GeoM boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, the axial transmitting antennas T1 and T2 alternately transmit signals during detection. The electromotive force received at two azimuth angles on one side is as follows:

[0030] ;

[0031] ;

[0032] In the formula, , These represent the coaxial and cross components of the electromotive force measured by the composite receiving antenna. For the structural parameters of the composite antenna, , These represent the number of turns in the axial and radial portions of the composite antenna, respectively. , These are the effective areas of the composite antenna along the axial and radial directions, respectively.

[0033] GeosD boundary detection mode: Employing low-to-medium transmission frequencies of 400kHz and 100kHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, during detection, axial transmitting antennas T1 and T2 alternately transmit signals. The received electromotive force at two azimuth angles on a single side is:

[0034] ;

[0035] ;

[0036] GeoD boundary detection mode: Uses low and medium transmission frequencies of 400kHz and 100kHz, and sets symmetrical compensation for axial transmitting antennas T5 and T6 and composite receiving antennas R3 and R4. During detection, axial transmitting antennas T5 and T6 transmit signals alternately. The electromotive force received under two azimuth angles on one side is the same as GeoD boundary detection mode.

[0037] The formulas for calculating the single-side amplitude ratio and phase difference of geological signals under the four source-distance boundary detection modes (GeoN, GeoM, GeoSD, and GeoD) are as follows:

[0038] ;

[0039] In the formula, , These are the azimuth angles of a single-sided receiving antenna. and( The measured electromotive force is then used; subsequently, the bilateral synthesized signal is symmetrically processed to obtain the amplitude ratio geological signal GA and the phase difference geological signal GP.

[0040] Optionally, in sliding drilling mode, the signal transmission and reception methods for the four source distance boundary detection modes—GeoN, GeoM, GeoSD, and GeoD—are as follows:

[0041] GeoN boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrical compensation for tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2, the tilted transmitting antennas T3 and T4 alternately transmit signals during detection. The average of the two received signals is taken as the electromotive force at two azimuth angles, as follows:

[0042] ;

[0043] In the formula, , and , These are the coaxial and cross components of the electromotive force at two source distances, respectively.

[0044] GeoM boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4 are symmetrically compensated. During detection, axial transmitting antennas T1 and T2 alternately transmit signals, and the two received signals are taken as the electromotive forces at two azimuth angles, as follows:

[0045] ;

[0046] ;

[0047] In the formula, , and , These are the coaxial and cross components of the two received electromotive forces, respectively. For the structural parameters of the composite antenna, , These represent the number of turns in the axial and radial portions of the composite antenna, respectively. , These are the effective areas of the composite antenna along the axial and radial directions, respectively. This refers to the serial number of the composite receiving antenna;

[0048] GeosD boundary detection mode: Employing low-to-medium transmission frequencies of 400kHz and 100kHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, during detection, axial transmitting antennas T1 and T2 alternately transmit signals. The two received signals are taken as the electromotive forces at two azimuth angles, as follows:

[0049] ;

[0050] ;

[0051] GeoD boundary detection mode: Uses low and medium transmission frequencies of 400kHz and 100kHz, sets symmetrical compensation of axial transmitting antennas T5 and T6 and composite receiving antennas R3 and R4, and transmits signals alternately by axial transmitting antennas T5 and T6 during detection. The electromotive force at the two azimuth angles is the same as GeoD boundary detection mode.

[0052] The formulas for calculating the amplitude ratio and phase difference of geological signals under the four source-distance boundary detection modes (GeoN, GeoM, GeoSD, and GeoD) are as follows:

[0053] ;

[0054] In the formula, , Azimuth angles provided by both sides and( The electromotive force is measured under ( ).

[0055] The beneficial effects of this invention are that it constructs multiple detection modes under multi-frequency and multi-source distance conditions, providing rich information on formation electrical properties and interfaces, and achieving high-definition multi-boundary detection of formations within 12m around the well. The orthogonal composite antenna proposed in this invention effectively increases the proportion of azimuth signals, doubling the detection distance compared to traditional methods, while effectively eliminating dependence on rotary drilling and broadening the instrument's applicability. Furthermore, the azimuth resistivity design allows the instrument to provide resistivity data for each sector for wellbore resistivity imaging, as well as the average resistivity around the well to reflect the overall electrical level of the formation, even during rotary drilling. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of a drilling electromagnetic wave multi-boundary detection device according to Embodiment 1 of the present invention;

[0057] Figure 2A This is a schematic diagram of the composite receiving antenna R3 structure shown in Embodiment 1 of the present invention;

[0058] Figure 2B This is a schematic diagram of the composite receiving antenna R4 structure shown in Embodiment 1 of the present invention;

[0059] Figure 2C This is a schematic diagram of the axial transmit / receive antenna structure shown in Embodiment 1 of the present invention;

[0060] Figure 2D This is a schematic diagram of the tilted transmitting antenna structure shown in Embodiment 1 of the present invention;

[0061] Figure 3 This is a schematic diagram of the resistivity detection mode transmit-receive antenna combination shown in Embodiment 2 of the present invention;

[0062] Figure 4 This is a schematic diagram of the transmit-receive antenna combination for boundary detection mode shown in Embodiment 2 of the present invention;

[0063] Figure 5 This is a resistivity detection mode amplitude-to-resistivity conversion chart shown in Embodiment 2 of the present invention;

[0064] Figure 6 This is a resistivity detection mode phase difference resistivity conversion diagram shown in Embodiment 2 of the present invention;

[0065] Figure 7 This is a graph showing the amplitude ratio of the boundary detection mode to the geological signal, as illustrated in Embodiment 2 of the present invention.

[0066] Figure 8 This is a phase difference geological signal curve of the boundary detection mode shown in Embodiment 2 of the present invention. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] Example 1

[0069] A drilling electromagnetic wave multi-boundary detection device, such as Figure 1 As shown, the system includes a novel six-transmitter, four-receiver multi-boundary detection coil system and an instrument drill collar. The six-transmitter, four-receiver multi-boundary detection coil system includes: axial receiving antennas R1 and R2, and axial transmitting antennas T1, T2, T5, and T6. The axial transmitting / receiving antenna structure is as follows: Figure 2C As shown, the tilted transmitting antennas T3 and T4 have the following structure: Figure 2D As shown, the composite receiving antennas R3 and R4 have the following structure: Figure 2A , Figure 2B As shown, the midpoint of the axial receiving antennas R1 and R2 is the center of the coil system, and the remaining antennas are symmetrically distributed in the grooves on the surface of the instrument's drill collar along the center of the coil system. According to the order of distance from the center of the coil system from near to far, the antennas are arranged as follows: axial receiving antennas R1 / R2 (about 4 in from the center), axial transmitting antennas T1 / T2 (about 20 in from the center), tilted transmitting antennas T3 / T4, axial transmitting antennas T5 / T6 (about 35 in from the center), and composite receiving antennas R3 / R4 (about 50 in from the center).

[0070] Optionally, the composite receiving antennas R3 and R4 are formed by winding a radial antenna and an axial antenna in opposite directions, and can be implemented in two ways:

[0071] (1) Divide an axial antenna into two semi-circular ring antennas, offset them by a certain distance along the axial direction, and reconnect the corresponding interfaces with the antenna to form a composite antenna with the same number of turns and different areas in the axial and radial parts. The two semi-circular ring axial antennas are different source distances and are symmetrical about the midpoint of the entire antenna structure, which is equivalent to a complete axial antenna in the same position as the radial part.

[0072] (2) Place an axial antenna and a radial antenna horizontally, and connect them in opposite directions through electronic circuitry to form a composite antenna in which the area and number of turns of the axial and radial parts are relatively independent.

[0073] Optionally, the tilted transmitting antenna T3 and the composite receiving antenna R4 are on one working plane, and the tilted transmitting antenna T4 and the composite receiving antenna R3 are on another working plane, with the azimuth angles between the two working planes differing by 90°; the axial transmitting antennas T1, T2, T5, and T6 have no circumferential differences from the axial receiving antennas R1 and R2, and the working planes are not distinguished.

[0074] Example 2

[0075] This embodiment discloses a drilling electromagnetic wave multi-boundary detection method, using the detection device in Embodiment 1, including the following steps:

[0076] A two-layer horizontal layered medium model with a formation resistivity of 100Ω·m:1Ω·m was established, and the well inclination angle was 90°.

[0077] The receiving antenna electromotive force is measured in resistivity detection modes at four scales: RS, RM, RsD, and RD. Figure 3 The diagram shown is a schematic of the transmit-receive antenna combination for resistivity detection modes provided in Embodiment 2 of the present invention, wherein the four resistivity detection modes are RS, RM, RsD, and RD, respectively:

[0078] RS resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for axial transmitting antennas T1 and T2 and axial receiving antennas R1 and R2. During detection, the axial transmitting antennas T1 and T2 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , , , These are the coaxial components of the electromotive force at the two source distances, respectively.

[0079] RM resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2. During detection, the tilted transmitting antennas T3 and T4 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , , This is the azimuth angle of the instrument's rotation. , These are the cross components of the electromotive force at the two source distances, respectively;

[0080] RsD resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for axial transmitting antennas T5 and T6 and axial receiving antennas R1 and R2. During detection, axial transmitting antennas T5 and T6 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , ;

[0081] RD resistivity detection mode: A low-to-medium transmission frequency of 400kHz and 100kHz is used, with symmetrical compensation of axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4. During detection, axial transmitting antennas T1 and T2 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , .

[0082] Based on the electromotive force of the receiving antenna, the single-sided amplitude ratio Att and phase difference PS signals under the four resistivity detection modes RS, RM, RsD, and RD are calculated as follows:

[0083] ;

[0084] The average values ​​of the bilateral amplitude ratio and phase difference signals are then input into the apparent resistivity conversion chart to obtain the four levels of apparent resistivity Ra (RS, RM, RsD, RD) and apparent resistivity Rp (phase difference) around the well. Figure 5 , Figure 6 The figures show the resistivity conversion graphs for amplitude ratio and phase difference resistivity in the resistivity detection mode provided in Embodiment 2 of the present invention. As can be seen from the figures, when given thresholds of 0.02 dB (amplitude ratio) and 0.05 deg (phase difference), the resistivity detection range of the phase difference signal is larger than that of the amplitude ratio signal under the same source-distance combination at the same frequency, and each signal has a good detection range. Furthermore, with increasing frequency and source distance, the resistivity detection range of each signal shows a significant improvement.

[0085] The receiving antenna electromotive force was measured for four source-distance boundary detection modes: GeoN, GeoM, GeoSD, and GeoD. Figure 4 The diagram shown is a schematic of the transmit-receive antenna combination for the boundary detection mode provided in Embodiment 2 of the present invention. The boundary detection mode provides two working states: rotary drilling and sliding drilling. The corresponding mode is selected according to the actual situation.

[0086] (1) In rotary drilling mode, the signal transmission and reception methods for the four source distance boundary detection modes GeoN, GeoM, GeoSD, and GeoD are as follows:

[0087] GeoN boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrically compensated tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2, the tilted transmitting antennas T3 and T4 alternately transmit signals during detection. The electromotive force (EMF) at each of the two azimuth angles on a single side is taken as the average of the EMFs of the two receiving antennas, as follows:

[0088] ;

[0089] ;

[0090] In the formula, , These are the coaxial components of the electromotive force at the two source distances, respectively. , These are the cross components of the electromotive force at the two source distances, respectively;

[0091] GeoM boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, the axial transmitting antennas T1 and T2 alternately transmit signals during detection. The electromotive force received at two azimuth angles on one side is as follows:

[0092] ;

[0093] ;

[0094] In the formula, , These represent the coaxial and cross components of the electromotive force measured by the composite receiving antenna. For the structural parameters of the composite antenna, , These represent the number of turns in the axial and radial portions of the composite antenna, respectively. , These are the effective areas of the composite antenna along the axial and radial directions, respectively.

[0095] GeosD boundary detection mode: Employing low-to-medium transmission frequencies of 400kHz and 100kHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, during detection, axial transmitting antennas T1 and T2 alternately transmit signals. The received electromotive force at two azimuth angles on a single side is:

[0096] ;

[0097] ;

[0098] GeoD boundary detection mode: Uses low and medium transmission frequencies of 400kHz and 100kHz, and sets symmetrical compensation for axial transmitting antennas T5 and T6 and composite receiving antennas R3 and R4. During detection, axial transmitting antennas T5 and T6 transmit signals alternately. The electromotive force received under two azimuth angles on one side is the same as GeoD boundary detection mode.

[0099] Based on the receiving antenna electromotive force, the single-sided amplitude ratio and phase difference geological signals are calculated under the four source-distance boundary detection modes: GeoN, GeoM, GeoSD, and GeoD. The calculation formula is as follows:

[0100] ;

[0101] In the formula, , These are the azimuth angles of a single-sided receiving antenna. and( The measured electromotive force is then used; subsequently, the bilateral synthesized signal is symmetrically processed to obtain the amplitude ratio geological signal GA and the phase difference geological signal GP.

[0102] (2) In sliding drilling mode, the signal transmission and reception methods for the four source distance boundary detection modes, GeoN, GeoM, GeoSD, and GeoD, are as follows:

[0103] GeoN boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrical compensation for tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2, the tilted transmitting antennas T3 and T4 alternately transmit signals during detection. The average of the two received signals is taken as the electromotive force at two azimuth angles, as follows:

[0104] ;

[0105] In the formula, , and , These are the coaxial and cross components of the electromotive force at two source distances, respectively.

[0106] GeoM boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4 are symmetrically compensated. During detection, axial transmitting antennas T1 and T2 alternately transmit signals, and the two received signals are taken as the electromotive forces at two azimuth angles, as follows:

[0107] ;

[0108] ;

[0109] In the formula, , and , These are the coaxial and cross components of the two received electromotive forces, respectively. For the structural parameters of the composite antenna, , These represent the number of turns in the axial and radial portions of the composite antenna, respectively. , These are the effective areas of the composite antenna along the axial and radial directions, respectively. This refers to the serial number of the composite receiving antenna;

[0110] GeosD boundary detection mode: Employing low-to-medium transmission frequencies of 400kHz and 100kHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, during detection, axial transmitting antennas T1 and T2 alternately transmit signals. The two received signals are taken as the electromotive forces at two azimuth angles, as follows:

[0111] ;

[0112] ;

[0113] GeoD boundary detection mode: Uses low and medium transmission frequencies of 400kHz and 100kHz, sets symmetrical compensation of axial transmitting antennas T5 and T6 and composite receiving antennas R3 and R4, and transmits signals alternately by axial transmitting antennas T5 and T6 during detection. The electromotive force at the two azimuth angles is the same as GeoD boundary detection mode.

[0114] Based on the electromotive force of the receiving antenna, the amplitude ratio geological signal and phase difference geological signal under the four source-distance boundary detection modes (GeoN, GeoM, GeoSD, and GeoD) are calculated using the following formulas:

[0115] ;

[0116] In the formula, , Azimuth angles provided by both sides and( The electromotive force is measured under ( ).

[0117] Figure 7 The amplitude ratio geological signal curve provided in this embodiment shows that, given a threshold of 0.02dB, the amplitude ratio geological signal curve under the 120in-100kHz source distance-frequency combination achieves the maximum exploration distance (11.1m). Figure 8The phase difference geological signal curve provided in this embodiment shows that, given a threshold of 0.05 degrees, the phase difference geological signal curve achieves the maximum probe distance (12.5 m) under the source-frequency combination of 120 in - 400 kHz. This is in conjunction with this embodiment. Figure 7 and Figure 8 As can be seen, the present invention provides multiple geological signal curves under multiple frequency and multiple source distances, and the exploration distances of different geological signal curves are arranged sequentially to form a boundary detection system of different depths around the well from near to far.

[0118] This invention constructs a novel six-transmitter, four-receiver high-definition multi-boundary detection coil system, providing four resistivity measurement modes: shallow (RS), medium (RM), relatively deep (RSD), and deep (RD), and four source-distance boundary detection modes: near (GeoN), medium (GeoM), relatively far (GeoD), and far (GeoD). Combined with three-frequency transmission, it provides 32 curves. Deep (RD) resistivity measurement employs symmetrical axial transmission and symmetrical orthogonal composite antenna reception, while medium source-distance (RM) resistivity measurement employs symmetrical orthogonal tilted transmission and symmetrical axial reception, respectively providing resistivity measurement and imaging of formations within 6m and 2.5m of the well perimeter; shallow (RS)... The deep (RsD) source-distance resistivity measurement employs symmetrical axial transmission and reception, enabling resistivity measurements of formations within 1m and 4m around the well. The far (GeoD) and relatively far (GeoSD) boundary detection modes utilize symmetrical axial transmission and symmetrical orthogonal composite reception, combined with a method for synthesizing azimuth geological signals from sliding and rotary drilling states, achieving detection ranges of 10-12m and 7-9m respectively. The medium (GeoM) distance boundary detection mode employs symmetrical axial transmission and symmetrical orthogonal composite antenna reception, achieving a detection range of 4-6m. The near (GeoN) boundary detection mode is based on symmetrical tilted transmission and symmetrical axial reception, with a detection range of 1-3m. This invention constructs multiple detection modes under multi-frequency and multi-source-distance conditions, providing rich information on formation electrical properties and interfaces, achieving high-definition multi-boundary detection of formations within 12m around the well. The orthogonal composite antenna proposed in this invention effectively increases the proportion of azimuth signals, doubling the detection distance compared to traditional methods, while effectively eliminating dependence on rotary drilling, thus broadening the instrument's applicability.

[0119] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A drilling electromagnetic wave multi-boundary detection device, characterized in that, The system includes a six-transmitter, four-receiver multi-boundary detection coil system, which comprises: axial receiving antennas R1 and R2, axial transmitting antennas T1, T2, T5, and T6, tilted transmitting antennas T3 and T4, and composite receiving antennas R3 and R4. The midpoint of the axial receiving antennas R1 and R2 is the center of the coil system, and the remaining antennas are symmetrically distributed along the center of the coil system in the grooves on the surface of the instrument's drill collar. According to the order of distance from the center of the coil system from near to far, the antennas are arranged as follows: axial receiving antennas R1 / R2, axial transmitting antennas T1 / T2, tilted transmitting antennas T3 / T4, axial transmitting antennas T5 / T6, and composite receiving antennas R3 / R4. The composite receiving antennas R3 and R4 are formed by winding a radial antenna and an axial antenna in opposite directions, and can be implemented in two ways: (1) Divide an axial antenna into two semi-circular ring antennas, stagger them along the axial direction, and reconnect the corresponding interfaces with the antenna to form a composite antenna with the same number of turns and different areas in the axial and radial parts. The two semi-circular ring axial antennas are different source distances and are symmetrical about the midpoint of the entire antenna structure, which is equivalent to a complete axial antenna in the same position as the radial part. (2) Place an axial antenna and a radial antenna horizontally, and connect them in opposite directions through electronic circuitry to form a composite antenna in which the area and number of turns of the axial and radial parts are relatively independent. The tilted transmitting antenna T3 and the composite receiving antenna R4 are on one working plane, and the tilted transmitting antenna T4 and the composite receiving antenna R3 are on another working plane, with an azimuth angle difference of 90° between the two working planes; the axial transmitting antennas T1, T2, T5, and T6 have no circumferential difference from the axial receiving antennas R1 and R2, and their working planes are not distinguished.

2. A method for multi-boundary detection using electromagnetic waves while drilling, characterized in that, The apparatus of claim 1 comprises the following steps: A two-layer horizontal layered medium model was established with a well inclination angle of 90°. Measure the receiving antenna electromotive force for four resistivity detection modes: RS, RM, RsD, and RD. The receiving antenna electromotive force was measured for four source distance boundary detection modes: GeoN, GeoM, GeoSD, and GeoD.

3. The drilling electromagnetic wave multi-boundary detection method as described in claim 2, characterized in that, The four resistivity detection modes, RS, RM, RsD, and RD, are as follows: RS resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for axial transmitting antennas T1 and T2 and axial receiving antennas R1 and R2. During detection, the axial transmitting antennas T1 and T2 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , , , These are the coaxial components of the electromotive force at the two source distances, respectively. RM resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2. During detection, the tilted transmitting antennas T3 and T4 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , , This is the azimuth angle of the instrument's rotation. , These are the cross components of the electromotive force at the two source distances, respectively; RsD resistivity detection mode: A medium-high transmission frequency of 400kHz and 2MHz is used, with symmetrical compensation for axial transmitting antennas T5 and T6 and axial receiving antennas R1 and R2. During detection, axial transmitting antennas T5 and T6 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , ; RD resistivity detection mode: A low-to-medium transmission frequency of 400kHz and 100kHz is used, with symmetrical compensation of axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4. During detection, axial transmitting antennas T1 and T2 alternately transmit signals. The electromotive forces of the two receiving antennas on each side are as follows: , .

4. The drilling electromagnetic wave multi-boundary detection method as described in claim 3, characterized in that, Under the four resistivity detection modes RS, RM, RsD, and RD, the single-sided amplitude ratio Att and phase difference PS signals are calculated as follows: ； After averaging the bilateral amplitude ratio and phase difference signals, the apparent resistivity conversion chart is used to obtain the amplitude ratio apparent resistivity Ra and phase difference apparent resistivity Rp under four resistivity detection modes: RS, RM, RsD, and RD.

5. The drilling electromagnetic wave multi-boundary detection method as described in claim 2, characterized in that, Source distance boundary detection is divided into rotary drilling mode and sliding drilling mode.

6. The drilling electromagnetic wave multi-boundary detection method as described in claim 5, characterized in that, In rotary drilling mode, the signal transmission and reception methods for the four source distance boundary detection modes—GeoN, GeoM, GeoSD, and GeoD—are as follows: GeoN boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrically compensated tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2, the tilted transmitting antennas T3 and T4 alternately transmit signals during detection. The electromotive force (EMF) at each of the two azimuth angles on a single side is taken as the average of the EMFs of the two receiving antennas, as follows: ； ； In the formula, , These are the coaxial components of the electromotive force at the two source distances, respectively. , These are the cross components of the electromotive force at the two source distances, respectively; GeoM boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, the axial transmitting antennas T1 and T2 alternately transmit signals during detection. The electromotive force received at two azimuth angles on one side is as follows: ； ； In the formula, , These represent the coaxial and cross components of the electromotive force measured by the composite receiving antenna. For the structural parameters of the composite antenna, , These represent the number of turns in the axial and radial portions of the composite antenna, respectively. , These are the effective areas of the composite antenna along the axial and radial directions, respectively. GeosD boundary detection mode: Employing low-to-medium transmission frequencies of 400kHz and 100kHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, during detection, axial transmitting antennas T1 and T2 alternately transmit signals. The received electromotive force at two azimuth angles on a single side is: ； ； GeoD boundary detection mode: Uses low and medium transmission frequencies of 400kHz and 100kHz, and sets symmetrical compensation for axial transmitting antennas T5 and T6 and composite receiving antennas R3 and R4. During detection, axial transmitting antennas T5 and T6 transmit signals alternately. The electromotive force received under two azimuth angles on one side is the same as GeoD boundary detection mode. The formulas for calculating the single-side amplitude ratio and phase difference of geological signals under the four source-distance boundary detection modes (GeoN, GeoM, GeoSD, and GeoD) are as follows: ； In the formula, , These are the azimuth angles of a single-sided receiving antenna. and( The measured electromotive force is then used; subsequently, the bilateral synthesized signal is symmetrically processed to obtain the amplitude ratio geological signal GA and the phase difference geological signal GP.

7. The drilling electromagnetic wave multi-boundary detection method as described in claim 5, characterized in that, In sliding drilling mode, the signal transmission and reception methods for the four source distance boundary detection modes (GeoN, GeoM, GeoSD, and GeoD) are as follows: GeoN boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, with symmetrical compensation for tilted transmitting antennas T3 and T4 and axial receiving antennas R1 and R2, the tilted transmitting antennas T3 and T4 alternately transmit signals during detection. The average of the two received signals is taken as the electromotive force at two azimuth angles, as follows: ； In the formula, , These are the coaxial components of the electromotive force at the two source distances, respectively. , These are the cross components of the electromotive force at the two source distances, respectively; GeoM boundary detection mode: Employing a medium-high transmission frequency of 400kHz and 2MHz, axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4 are symmetrically compensated. During detection, axial transmitting antennas T1 and T2 alternately transmit signals, and the two received signals are taken as the electromotive forces at two azimuth angles, as follows: ； ； In the formula, , These are the coaxial components of the two received electromotive forces, respectively. , These are the cross components of the two received electromotive forces, respectively. For the structural parameters of the composite antenna, , These represent the number of turns in the axial and radial portions of the composite antenna, respectively. , These are the effective areas of the composite antenna along the axial and radial directions, respectively. This refers to the serial number of the composite receiving antenna; GeosD boundary detection mode: Employing low-to-medium transmission frequencies of 400kHz and 100kHz, with symmetrically compensated axial transmitting antennas T1 and T2 and composite receiving antennas R3 and R4, during detection, axial transmitting antennas T1 and T2 alternately transmit signals. The two received signals are taken as the electromotive forces at two azimuth angles, as follows: ； ； GeoD boundary detection mode: Uses low and medium transmission frequencies of 400kHz and 100kHz, sets symmetrical compensation of axial transmitting antennas T5 and T6 and composite receiving antennas R3 and R4, and transmits signals alternately by axial transmitting antennas T5 and T6 during detection. The electromotive force at the two azimuth angles is the same as GeoD boundary detection mode. The formulas for calculating the amplitude ratio (GA) and phase difference (GP) of the geological signal under the four source-distance boundary detection modes (GeoN, GeoM, GeoSD, and GeoD) are as follows: ； In the formula, , These are the azimuth angles of the two-sided receiving antennas. and( The electromotive force is measured under ( ).

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