A permanent pressure measurement system for underground electromagnetic wave transmission

Abstract

The present invention relates to a downhole electromagnetic wave transmission permanent pressure measurement system, comprising: an electromagnetic wave transmission permanent pressure measurement nipple and a wellhead device, wherein the electromagnetic wave transmission permanent pressure measurement nipple is fixedly connected to the oil pipe and is located on the inner side of the casing, and is electromagnetically coupled with the casing, and is used to collect downhole data according to a first electromagnetic wave signal, and generate a second electromagnetic wave signal according to the downhole data; the wellhead device is connected to the wellhead end of the casing, and is electromagnetically coupled with the casing, and is used to generate a first electromagnetic wave signal according to a control instruction, or, receive a second electromagnetic wave signal; the frequency of the first electromagnetic wave signal and the second electromagnetic wave signal is 10mHz~10Hz. The electromagnetic wave transmission permanent pressure measurement nipple and the wellhead device are electromagnetically coupled with the casing, so as to realize the propagation of the first electromagnetic wave signal and the second electromagnetic wave signal between the downhole and the wellhead, thereby realizing the real-time interaction of the control instruction and the downhole data, and meeting the application of complex well conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum well logging, and in particular relates to an underground electromagnetic wave transmission permanent pressure measurement system. Background Art

[0002] During the exploitation of oil and gas wells, it is required to continuously monitor the parameters of the oil and gas wells for a long time, such as the temperature and pressure of the downhole fluid and other important parameters, so as to provide effective data support for understanding the production status of the oil wells, accurately analyzing the dynamic characteristics of downhole oil and gas resources, and reasonably evaluating the development effect of the oil reservoir.

[0003] In the separated space underground, it is impossible to carry out cable operations. At this time, wireless communication technology is needed to transmit data. Acoustic wave communication, high-frequency electromagnetic wave wireless communication, and mud pulse wireless communication technology are three commonly used underground wireless communication technologies. Among them, mud pulse wireless communication technology converts the data to be transmitted into a driving pulse 0 / 1 change through encoding, drives the mud pulse generator to generate mud pulses, and the receiver analyzes the transmission data underground by detecting the change of mud pulse signals. Since the transmission medium of mud pulse wireless communication technology is drilling mud, the viscosity, sand content and other parameters of the mud have a great influence on the communication. Mud pulse wireless communication technology is widely used in drilling measurement, but as time goes by, the drilling mud invested in the early stage can no longer carry this wireless communication method. Acoustic wave communication uses coding technology to convert transmission data into mechanical vibration. The vibration is consistent with the propagation law of sound waves in the medium. If it hits the oil casing according to the coding law, the mechanical vibration will propagate from the impact point to the surroundings. Therefore, this communication method has poor directionality and large attenuation, and it is difficult to apply in deeper wells. High-frequency electromagnetic wave wireless communications are widely used on the ground, such as WIFI, mobile phones, etc., but underground, due to the influence of media such as well fluid, high-frequency electromagnetic waves attenuate quickly and cannot be used.

[0004] In summary, the existing underground wireless communication technology is greatly affected by the transmission medium, signal transmission is difficult in complex well conditions, and its application is limited. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a downhole electromagnetic wave transmission permanent pressure measurement system. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] The present invention provides a downhole electromagnetic wave transmission permanent pressure measurement system, comprising: an electromagnetic wave transmission permanent pressure measurement nipple and wellhead equipment, wherein:

[0007] The electromagnetic wave transmission permanent pressure measurement nipple is fixedly connected to the oil pipe and is located inside the casing. It is electromagnetically coupled to the casing and is used to collect downhole data according to the first electromagnetic wave signal and generate a second electromagnetic wave signal according to the downhole data.

[0008] The wellhead equipment is connected to the wellhead end of the casing and is electromagnetically coupled to the casing for generating a first electromagnetic wave signal according to a control instruction, or receiving the second electromagnetic wave signal; the frequencies of the first electromagnetic wave signal and the second electromagnetic wave signal are 10mHz~10Hz.

[0009] In an achievable manner, the electromagnetic wave transmission permanent pressure measurement nipple comprises: a first joint, a second joint, a first insulation unit, a second insulation unit, an electromagnetic wave transmission unit, a main control unit and a measurement unit, wherein:

[0010] The first joint and the second joint are fixedly connected to the outer wall of the oil pipe in sequence from top to bottom;

[0011] The first insulating unit, the electromagnetic wave transmission unit, the main control unit and the second insulating unit are fixed in sequence from top to bottom between the first connector and the second connector;

[0012] The electromagnetic wave transmission unit is used to generate a first sinusoidal wave coded signal according to the first electromagnetic wave signal, or to generate the second electromagnetic wave signal according to the second sinusoidal wave coded signal;

[0013] The main control unit is used to decode the first sine wave coded signal to generate a control signal, or to encode the downhole data to generate a second sine wave coded signal;

[0014] The measuring unit is arranged inside the second joint, and is used for collecting the downhole data according to the control signal.

[0015] In an achievable manner, the electromagnetic wave transmission permanent pressure measurement short joint further includes: a battery unit, a first electromagnetic shielding block and a second electromagnetic shielding block;

[0016] The first electromagnetic shielding block, the battery unit and the second electromagnetic shielding block are fixed in sequence from top to bottom between the electromagnetic wave transmission unit and the main control unit.

[0017] In one achievable manner, the measuring unit includes: a temperature sensor and a pressure sensor, wherein:

[0018] The temperature sensor is used to obtain the temperature inside the oil pipe and the temperature of the annulus between the casing and the oil pipe;

[0019] The pressure sensor is used to obtain the pressure inside the oil pipe and the annular space pressure between the casing and the oil pipe.

[0020] In one achievable manner, the main control unit includes: a decoding circuit and an encoding circuit;

[0021] The decoding circuit and the encoding circuit are both connected to the electromagnetic wave transmission unit; wherein,

[0022] The decoding circuit is used to reversely modulate the first sine wave coded signal to form a first square wave coded signal, and decode the first square wave coded signal to obtain a control signal;

[0023] The encoding circuit is used to encode the downhole data according to a time period to form a second square wave encoded signal, and to perform sinusoidal wave modulation on the second square wave encoded signal to form a second sinusoidal wave encoded signal.

[0024] In one achievable manner, the electromagnetic wave transmission unit includes a coil sensor.

[0025] In one achievable manner, the electromagnetic wave transmission permanent pressure measurement sub-node further includes: a timing unit;

[0026] The timing unit is electrically connected to the main control unit and is used for timing. When the timing reaches a preset time, a wake-up signal is sent to the main control unit.

[0027] In one practicable manner, it further includes: a plurality of downhole electromagnetic repeater short sections;

[0028] The plurality of downhole electromagnetic repeater short sections are all located between the wellhead equipment and the electromagnetic wave transmission permanent pressure measurement short section, and are sequentially sleeved on the oil pipe from top to bottom for forwarding the first electromagnetic wave signal and the second electromagnetic wave signal.

[0029] In one practicable manner, the electromagnetic wave transmission permanent pressure measurement nipple is threadedly connected to the oil pipe.

[0030] In one achievable manner, both the first joint and the second joint are threadedly connected to the oil pipe.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention discloses a downhole electromagnetic wave transmission permanent pressure measurement system, which realizes the propagation of the first electromagnetic wave signal and the second electromagnetic wave signal between the downhole and the wellhead through electromagnetic wave transmission permanent pressure measurement short joint and wellhead equipment and casing electromagnetic coupling, thereby realizing real-time interaction between control instructions and downhole data. The system can measure downhole data in real time, and the transmission medium of the first electromagnetic wave signal and the second electromagnetic wave signal is the casing, and the signal transmission is stable, which can meet the application of complex well conditions. In addition, the first electromagnetic wave signal and the second electromagnetic wave signal are both low-frequency electromagnetic waves, which are less affected by the propagation medium, and the propagation distance in the well is much greater than that of ultrasonic waves and high-frequency electromagnetic waves, and can directly communicate in deep wells where the mineralization does not change much. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a downhole electromagnetic wave transmission permanent pressure measurement system provided by an embodiment of the present invention;

[0034] Figure 2 It is a structural schematic diagram of an electromagnetic wave transmission permanent pressure measurement nipple provided by an embodiment of the present invention;

[0035] Figure 3 is a schematic diagram of the circuit structure of a main control unit provided by an embodiment of the present invention;

[0036] Figure 4 is a schematic diagram of data signal conversion of a main control unit provided by an embodiment of the present invention;

[0037] Figure 5 This is a working timing diagram of the electromagnetic wave transmission permanent pressure measurement short section provided by an embodiment of the present invention.

[0038] Reference numerals:

[0039] 1: Electromagnetic wave transmission permanent pressure measurement short section; 101: First joint; 102: First insulation unit; 103: Electromagnetic wave transmission unit; 104: First electromagnetic shielding block; 105: Battery unit; 106: Second electromagnetic shielding block; 107: Main control unit; 108: Second insulation unit; 109: Measuring unit; 1091: Temperature sensor; 1092: Pressure sensor; 110: Second joint; 2: Wellhead equipment; 3: Casing; 4: Oil pipe; 5: Downhole electromagnetic repeater short section; 6: Separator; 7: Section hoop. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0041] Embodiment 1

[0042] See also Figure 1 , Figure 1It is a structural schematic diagram of a downhole electromagnetic wave transmission permanent pressure measurement system provided by an embodiment of the present invention.

[0043] The present embodiment provides a downhole electromagnetic wave transmission permanent pressure measurement system, comprising: an electromagnetic wave transmission permanent pressure measurement short section 1 and a wellhead device 2. The electromagnetic wave transmission permanent pressure measurement short section 1 is fixedly connected to the oil pipe 4, and the electromagnetic wave transmission permanent pressure measurement short section 1 is located on the inner side of the casing 3, and is electromagnetically coupled with the casing 3. The electromagnetic wave transmission permanent pressure measurement short section 1 is used to collect downhole data according to the first electromagnetic wave signal, and to generate a second electromagnetic wave signal according to the downhole data. The wellhead device 2 is connected to the wellhead end of the casing 3, and is electromagnetically coupled with the casing 3. The wellhead device 2 is used to generate a first electromagnetic wave signal according to a control instruction, or to receive a second electromagnetic wave signal. The frequencies of the first electromagnetic wave signal and the second electromagnetic wave signal are 10mHz~10Hz.

[0044] In this embodiment, the electromagnetic wave transmission permanent pressure measurement nipple 1 and the oil pipe 4 are threadedly connected. The electromagnetic wave transmission permanent pressure measurement nipple 1 and the wellhead equipment 2 are electromagnetically coupled with the casing 3. The first electromagnetic wave signal and the second electromagnetic wave signal are coupled to the casing 3 through electromagnetic coupling and propagate along the casing 3, thereby realizing the propagation of the first electromagnetic wave signal and the second electromagnetic wave signal between the well and the wellhead, and realizing the real-time interaction of the control command and the downhole data. The system can measure downhole data in real time, and the transmission medium of the first electromagnetic wave signal and the second electromagnetic wave signal is the casing 3. The signal transmission is stable and meets the application of complex well conditions. In addition, the first electromagnetic wave signal and the second electromagnetic wave signal are both low-frequency electromagnetic waves, which are less affected by the propagation medium, and the propagation distance in the well is much greater than that of ultrasonic waves and high-frequency electromagnetic waves, and can communicate directly in deep wells with little change in mineralization.

[0045] In this embodiment, the electromagnetic wave transmission permanent pressure measurement nipple 1 includes: a first joint 101, a second joint 110, a first insulating unit 102, a second insulating unit 108, an electromagnetic wave transmission unit 103, a main control unit 107 and a measuring unit 109. The first joint 101 and the second joint 110 are fixedly connected to the outer wall of the oil pipe 4 from top to bottom. The first insulating unit 102, the electromagnetic wave transmission unit 103, the main control unit 107 and the second insulating unit 108 are fixed between the first joint 101 and the second joint 110 from top to bottom. The electromagnetic wave transmission unit 103 is used to generate a first sinusoidal wave coded signal according to the first electromagnetic wave signal, or to generate a second electromagnetic wave signal according to the second sinusoidal wave coded signal. The main control unit 107 is used to decode the first sinusoidal wave coded signal to generate a control signal, or to encode the downhole data to generate a second sinusoidal wave coded signal. The measuring unit 109 is arranged inside the second joint 110, and is used to collect downhole data according to the control signal.

[0046] In this embodiment, the electromagnetic wave transmission permanent pressure measurement nipple 1 further includes: a battery unit 105, a first electromagnetic shielding block 104, and a second electromagnetic shielding block 106. The first electromagnetic shielding block 104, the battery unit 105, and the second electromagnetic shielding block 106 are fixed in sequence from top to bottom between the electromagnetic wave transmission unit 103 and the main control unit 107.

[0047] Furthermore, the battery unit 105 includes a battery management subunit and a battery compartment. The battery compartment is used to supply power to the electromagnetic wave transmission permanent pressure measurement short section 1, and the battery management subunit is used to obtain the power of the battery compartment and the remaining working time.

[0048] In this embodiment, the measuring unit 109 includes: a temperature sensor 1091 and a pressure sensor 1092. The temperature sensor 1091 is used to obtain the temperature inside the tubing 4 and the annular temperature between the casing 3 and the tubing 4. The pressure sensor 1092 is used to obtain the pressure inside the tubing 4 and the annular pressure between the casing 3 and the tubing 4. It should be understood that the downhole data includes: the temperature inside the tubing 4, the annular temperature between the casing 3 and the tubing 4, the pressure inside the tubing 4 and the annular pressure between the casing 3 and the tubing 4.

[0049] See also Figure 2 , Figure 2 It is a structural schematic diagram of the electromagnetic wave transmission permanent pressure measurement short joint provided by an embodiment of the present invention. The first joint 101, the first insulating unit 102, the electromagnetic wave transmission unit 103, the first electromagnetic shielding block 104, the battery unit 105, the second electromagnetic shielding block 106, the main control unit 107, the second insulating unit 108 and the second joint 110 are arranged in sequence from top to bottom, and the measuring unit 109 is arranged inside the second joint 110. The first joint 101 and the second joint 110 are both threadedly connected to the outer wall of the oil pipe 4, the first insulating unit 102 is used to achieve electrical insulation between the electromagnetic wave transmission unit 103 and the upper oil pipe 4, the first electromagnetic shielding block 104 and the second electromagnetic shielding block 106 are used to avoid electromagnetic wave interference between adjacent units, and the second insulating unit 108 is used to achieve electrical insulation between the electromagnetic wave transmission unit 103 and the lower oil pipe 4. The electromagnetic wave transmission unit 103 and the casing 3 are electromagnetically coupled. The electromagnetic wave transmission unit 103 can generate a first sinusoidal wave coded signal under the action of the first electromagnetic wave signal, or couple the second sinusoidal wave coded signal to the casing 3 through electromagnetic coupling, so that an eddy current is generated on the casing 3 to form a second electromagnetic wave signal. In addition, due to the electrical insulation effect of the first insulating unit 102 and the second insulating unit 108, the micro-current signal can be prevented from propagating along the oil pipe 4, so that the first electromagnetic wave signal and the second electromagnetic wave signal can only propagate along the casing 3, thereby ensuring the signal strength.

[0050] See also Figure 3 , Figure 3 1 is a schematic diagram of the circuit structure of the main control unit provided in an embodiment of the present invention. Specifically, the main control unit 107 includes: a decoding circuit and an encoding circuit. The decoding circuit and the encoding circuit are both connected to the electromagnetic wave transmission unit 103. Among them, the decoding circuit is used to reversely modulate the first sinusoidal wave coded signal to form a first square wave coded signal, decode the first square wave coded signal, and obtain a control signal. The encoding circuit is used to encode the downhole data according to the time period to form a second square wave coded signal, and perform sinusoidal wave modulation on the second square wave coded signal to form a second sinusoidal wave coded signal. In this embodiment, the electromagnetic wave transmission unit 103 includes a coil sensor. Under the action of the second sinusoidal wave coded signal, the coil sensor generates an electromagnetic field, and couples on the casing 3 to generate a second electromagnetic wave signal. When the first electromagnetic wave signal is transmitted to the coil sensor along the casing 3, the coil sensor induces an electromagnetic field under the action of the first electromagnetic wave signal and outputs a first sinusoidal wave coded signal. The time period is a preset time period of the sending clock.

[0051] Furthermore, the decoding circuit includes a dual-way switch, a differential amplifier, a multi-order filter, an amplifier and an analog-to-digital converter connected in sequence, and one end of the dual-way switch is used as the input end of the decoding circuit and connected to the coil sensor. The output end of the analog-to-digital converter is used as the output end of the decoding circuit. The first electromagnetic wave signal is transmitted along the sleeve 3 to the coil sensor, and the first sinusoidal wave coded signal is coupled on the coil sensor. The first sinusoidal wave coded signal enters the decoding circuit through one end of the dual-way switch, and the multi-order filter reversely modulates the first sinusoidal wave coded signal to form a first square wave coded signal. The analog-to-digital converter converts the first square wave coded signal into a digital signal to obtain a control signal. The control signal and the control instruction contain the same information.

[0052] Furthermore, the encoding circuit includes transistors Q1~Q4 and a low-pass filter, wherein transistors Q1~Q4 constitute a full-bridge drive circuit. The control end of the full-bridge drive circuit is connected to the MOS tube drive signal, the power end is connected to the DC / DC power supply, the first output end is connected to the first end of the low-pass filter, and the second output end is connected to the second end of the low-pass filter. The output end of the low-pass filter is connected to the coil sensor. When sending the code, the encoding circuit works, and when receiving the code, the decoding circuit works. The measurement system provided in this embodiment does not need to set up an additional antenna, and uses the same coil sensor as a sensitive element for sending and receiving. Compared with the coil structure that uses dual coils for simultaneous sending and receiving, the length and weight are greatly reduced, and it is easier to construct on site. In this embodiment, the MOS tube drive signal includes Q1, Q4 control signals and Q2, Q3 control signals. The Q1, Q4 control signals are used to control transistors Q1 and Q4, and Q2, Q3 are used to control signal transistors Q2 and Q3.

[0053] See also Figure 4 , Figure 4: This is a schematic diagram of data signal conversion of the main control unit provided by an embodiment of the present invention. Taking the code sending process as an example, the main control unit 107 divides the downhole data into MOS tube drive signals (Q1, Q4 control signals and Q2, Q3 control signals) for controlling the full-bridge drive circuit according to the sending clock according to the time period of the sending clock. The full-bridge drive circuit outputs a second square wave coded signal in the form of positive and negative square waves according to the MOS tube drive signal. Since the positive and negative square wave signals contain high-order harmonics, direct input to the coil sensor will produce greater losses. Therefore, this embodiment converts the second square wave coded signal in the form of positive and negative square waves into a second sinusoidal coded signal in the form of a sine wave through a low-pass filter, and drives the coil sensor with the second sinusoidal coded signal in the form of a sine wave to generate a second electromagnetic wave signal on the casing 3.

[0054] In one achievable manner, the measuring unit 109 includes two temperature sensors 1091 and two pressure sensors 1092, wherein one temperature sensor 1091 is used to obtain the temperature inside the tubing 4, the other temperature sensor 1091 is used to obtain the annular space temperature between the casing 3 and the tubing 4, one pressure sensor 1092 is used to obtain the pressure inside the tubing 4, and the other pressure sensor 1092 is used to obtain the annular space pressure between the casing 3 and the tubing 4.

[0055] Furthermore, the temperature sensor 1091 is a thermistor, and the temperature is measured by a bridge plus differential circuit. The pressure sensor 1092 adopts a piezoresistive pressure sensor with a balanced bridge, and is amplified by a low-noise instrument amplifier, and outputs high-resolution and high-precision measurement data through temperature compensation. The coil sensor is an electromagnetic coil with a closed canned high-permeability material as the skeleton. The first insulating unit 102 and the second insulating unit 108 are both designed with non-magnetic stainless steel and high-strength organic materials, and are filled with magnetic shielding materials.

[0056] In an achievable manner, the electromagnetic wave transmission permanent pressure measurement nipple 1 further includes: a timing unit. The timing unit is electrically connected to the main control unit 107 and is used for timing. When the timing reaches a preset time, a wake-up signal is sent to the main control unit 107.

[0057] Specifically, see Figure 5The electromagnetic wave transmission permanent pressure measurement short section 1 is time-driven. In the initial state, the electromagnetic wave transmission permanent pressure measurement short section 1 is in a low power consumption state, and only the timing unit is in a working state. When the timing unit reaches the preset time, it wakes up the time and sends a wake-up signal to the main control unit 107. After receiving the wake-up signal, the main control unit 107 enters the data command waiting mode. The decoding circuit in the main control unit 107 works, waits to receive the handshake instruction sent by the wellhead equipment 2, and determines whether the handshake is successful. After the handshake is successful, the encoding circuit works, and the main control unit 107 obtains the downhole data collected by the measurement unit 109 (i.e. Figure 5 The main control unit 107 receives the downhole data from the measuring unit 109 (i.e., the power of the battery compartment and the remaining working time). At this time, the downhole data obtained by the main control unit 107 from the measuring unit 109 is the downhole data collected by the measuring unit 109 in the previous cycle. The encoding circuit converts the downhole data and the power data into a second sinusoidal wave encoding signal, inputs the second sinusoidal wave encoding signal into the electromagnetic wave transmission unit 103, generates a second electromagnetic wave signal and transmits it to the wellhead device 2. The wellhead device 2 receives the second electromagnetic wave signal and decodes it to complete the data collection. When the wellhead device 2 receives the second electromagnetic wave signal, it sends the reply data, and the main control unit 107 receives the reply data. Furthermore, the main control unit 107 determines whether the data is sent successfully based on whether the reply data is received. If the data fails to be sent, the data is sent repeatedly five times until the data is sent successfully. After the data is successfully sent, the main control unit 107 controls the timing unit to calibrate the time according to the time synchronization command issued by the wellhead equipment 2, and controls the measuring unit 109 to collect and store downhole data according to the control instruction issued by the wellhead equipment 2. The data collected by the measuring unit 109 this time is used for the next transmission. After the measurement unit 109 completes the collection, the electromagnetic wave transmission permanent pressure measurement short section 1 re-enters the low power consumption state and waits for the timing unit to wake up again. In this embodiment, if the handshake fails, it is determined whether the handshake time reaches five minutes. If it does not reach five minutes, it continues to wait for the handshake instruction to be received. If it reaches five minutes, it skips the data sending step and directly enters the time calibration and data collection step.

[0058] In an achievable manner, the downhole electromagnetic wave transmission permanent pressure measurement system further includes: a plurality of downhole electromagnetic repeater short sections 5. The plurality of downhole electromagnetic repeater short sections 5 are all located between the wellhead equipment 2 and the electromagnetic wave transmission permanent pressure measurement short section 1, and are sequentially sleeved on the oil pipe 4 from top to bottom, and are used to forward the first electromagnetic wave signal and the second electromagnetic wave signal.

[0059] In this embodiment, the oil well system is composed of a casing 3, an oil pipe 4, a plurality of separators 6 and a plurality of hoops 7. The casing 3 is coaxially sleeved on the periphery of the oil pipe 4, and there is a gap between the casing 3 and the oil pipe 4, namely, the annular space. A plurality of separators 6 are sleeved on the oil pipe 4 in sequence from top to bottom, and are used to separate the upper and lower well sections to achieve stratified fracturing and stratified water injection. A plurality of hoops 7 are sleeved on the casing 3 in sequence from top to bottom, and are used to connect the upper and lower sections of the casing 3. Among them, the casing 3 is preferably made of carbon steel. Carbon steel has good electrical conductivity. It should be understood that the electromagnetic wave signal generated by the electromagnetic wave transmission permanent pressure measurement short section 1, the wellhead equipment 2 and the downhole electromagnetic repeater short section 5 on the casing 3 through electromagnetic coupling is actually the eddy current generated by the coupling of the casing 3 under the action of the electromagnetic field. Therefore, the casing 3 made of carbon steel has a good transmission effect on the first electromagnetic wave signal and the second electromagnetic wave signal.

[0060] In this embodiment, the wellhead equipment 2 is a slip-type structure, which can be clamped on the outer wall of the casing 3 and connected to the casing 3. The wellhead equipment 2 is arranged in the casing 3 section below the oil tree. The wellhead equipment 2 is electrically connected to the host computer. The wellhead equipment 2 decodes the second electromagnetic wave signal to obtain downhole data. The host computer is used to store and process downhole data and generate control instructions according to the downhole data. Optionally, the control instructions can also be manually input into the host computer. The electromagnetic wave transmission permanent pressure measurement short section 1 is a hollow cylindrical structure, which is arranged on the periphery of the oil pipe 4 through a threaded sleeve. The structure of the wellhead equipment 2 and the downhole electromagnetic repeater short section 5 is different from the internal structure of the electromagnetic wave transmission permanent pressure measurement short section 1 only in that the wellhead equipment 2 does not include a measurement unit, and the downhole electromagnetic repeater short section 5 can choose whether to include a measurement unit according to actual needs. The principle of mutual conversion between data and electromagnetic wave signals in the wellhead equipment 2, the downhole electromagnetic repeater short section 5 and the electromagnetic wave transmission permanent pressure measurement short section 1 is the same. The number of downhole electromagnetic repeater short sections 5 is set according to the number of isolation areas and the number of high-mineralization well sections. The downhole electromagnetic repeater short section 5 can forward the first electromagnetic wave signal and the second electromagnetic wave signal propagated in the lower layer to the upper layer, thereby realizing the relay of the first electromagnetic wave signal and the second electromagnetic wave signal. The inner diameter of the measurement system provided in this embodiment is slightly larger than the oil pipe 4, and can be integrally sleeved on the outside of the oil pipe 4 through a threaded structure without affecting the internal construction of the oil pipe.

[0061] The downhole electromagnetic wave transmission permanent pressure measurement system provided in this embodiment realizes the electromagnetic coupling of the electromagnetic wave transmission permanent pressure measurement short section 1 and the wellhead equipment 2 with the casing 3, realizes the propagation of the first electromagnetic wave signal and the second electromagnetic wave signal between the downhole and the wellhead, thereby realizing the real-time interaction of the control command and the downhole data, and can obtain the pressure and temperature values ​​of the measurement point in real time, and provide a basis for fracturing, oil testing, and the water injection volume of the water injection layer, so as to prevent the occurrence of layer cross-layer, resulting in oil recovery failure and fracturing failure. The measurement system can be placed in the well for a long time and continuously monitor the pressure changes in the well for a period of time. The system can measure downhole data in real time, and the transmission medium of the first electromagnetic wave signal and the second electromagnetic wave signal is the casing 3, which does not rely on the external medium of the system, and the signal transmission is stable, which meets the application of complex well conditions. In addition, the first electromagnetic wave signal and the second electromagnetic wave signal are both low-frequency electromagnetic waves, which are less affected by the propagation medium, and the propagation distance in the well is much greater than that of ultrasonic waves and high-frequency electromagnetic waves, and can communicate directly in deep wells with little change in mineralization. In wells spanning multiple mineralizations, increasing the number of downhole electromagnetic repeater short sections 5 can achieve full well measurement.

[0062] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A downhole electromagnetic wave transmission permanent pressure measurement system, characterized in that: include: Electromagnetic wave transmission permanent pressure measurement nipples and wellhead equipment, among which, The electromagnetic wave transmission permanent pressure measurement nipple is fixedly connected to the oil pipe and is located inside the casing. It is electromagnetically coupled to the casing and is used to collect downhole data according to the first electromagnetic wave signal and generate a second electromagnetic wave signal according to the downhole data. The electromagnetic wave transmission permanent pressure measurement nipple comprises: a first joint, a second joint, a first insulation unit, a second insulation unit, an electromagnetic wave transmission unit, a main control unit and a measurement unit, wherein: The first joint and the second joint are fixedly connected to the outer wall of the oil pipe in sequence from top to bottom; The first insulating unit, the electromagnetic wave transmission unit, the main control unit and the second insulating unit are fixed in sequence from top to bottom between the first connector and the second connector; The electromagnetic wave transmission unit is used to generate a first sinusoidal wave coded signal according to the first electromagnetic wave signal, or to generate the second electromagnetic wave signal according to the second sinusoidal wave coded signal; The main control unit is used to decode the first sine wave coded signal to generate a control signal, or to encode the downhole data to generate a second sine wave coded signal; The measuring unit is arranged inside the second joint and is used to collect the downhole data according to the control signal; The wellhead equipment is connected to the wellhead end of the casing and is electromagnetically coupled to the casing for generating a first electromagnetic wave signal according to a control instruction, or receiving the second electromagnetic wave signal; the frequencies of the first electromagnetic wave signal and the second electromagnetic wave signal are 10mHz~10Hz.

2. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: The electromagnetic wave transmission permanent pressure measurement short section also includes: a battery unit, a first electromagnetic shielding block and a second electromagnetic shielding block; The first electromagnetic shielding block, the battery unit and the second electromagnetic shielding block are fixed in sequence from top to bottom between the electromagnetic wave transmission unit and the main control unit.

3. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: The measuring unit includes: a temperature sensor and a pressure sensor, wherein: The temperature sensor is used to obtain the temperature inside the oil pipe and the temperature of the annulus between the casing and the oil pipe; The pressure sensor is used to obtain the pressure inside the oil pipe and the annular space pressure between the casing and the oil pipe.

4. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: The main control unit includes: a decoding circuit and an encoding circuit; The decoding circuit and the encoding circuit are both connected to the electromagnetic wave transmission unit; wherein, The decoding circuit is used to reversely modulate the first sine wave coded signal to form a first square wave coded signal, and decode the first square wave coded signal to obtain a control signal; The encoding circuit is used to encode the downhole data according to a time period to form a second square wave encoded signal, and to perform sinusoidal wave modulation on the second square wave encoded signal to form a second sinusoidal wave encoded signal.

5. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 4, characterized in that: The electromagnetic wave transmission unit includes a coil sensor.

6. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: The electromagnetic wave transmission permanent pressure measurement short section also includes: a timing unit; The timing unit is electrically connected to the main control unit and is used for timing. When the timing reaches a preset time, a wake-up signal is sent to the main control unit.

7. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: Also includes: Several downhole electromagnetic repeater subs; The plurality of downhole electromagnetic repeater short sections are all located between the wellhead equipment and the electromagnetic wave transmission permanent pressure measurement short section, and are sequentially sleeved on the oil pipe from top to bottom for forwarding the first electromagnetic wave signal and the second electromagnetic wave signal.

8. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: The electromagnetic wave transmission permanent pressure measurement nipple is threadedly connected to the oil pipe.

9. The downhole electromagnetic wave transmission permanent pressure measurement system according to claim 1, characterized in that: The first joint and the second joint are both threadedly connected to the outer wall of the oil pipe.

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