Gas influx monitoring devices and methods for wellbores

Abstract

The embodiment of the present application provides a kind of gas invasion monitoring device and method of wellbore, belong to oil and gas drilling field.The gas invasion monitoring device includes: ultrasonic transducer, for transmitting pulse ultrasonic wave to the annulus pipe of wellbore in emission mode, pulse ultrasonic wave meets the mobile scatterer of set position in annulus pipe and occurs reflection and produces echo signal;And receive echo signal in receiving mode;Data processing device, for processing echo signal, to obtain the doppler amplitude of echo signal;And determination module, for determining whether gas invasion occurs in wellbore according to the doppler amplitude of echo signal.Relative to prior art, the gas invasion monitoring device of the present application has good axial resolution, can measure the fluid of specified position and then extract fluid information.Meanwhile, the present application has good timeliness and accuracy, can timely monitor early warning and increase well control time when gas invasion occurs.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling, and in particular to a gas intrusion monitoring device and method for wellbore. Background Technology

[0002] With increasingly complex geological conditions in oil and gas well development, drilling processes are prone to encountering abnormally high-pressure formations, leading to gas intrusion and various drilling safety accidents such as blowouts, which greatly threaten the lives of workers and environmental protection. Therefore, the prevention and control of blowouts and other accidents are playing an increasingly important role in the drilling process.

[0003] If gas intrusion occurs during drilling, it is difficult to detect in its initial stages using monitoring methods such as fluid increments or flow differential overflows in the drilling fluid pool. Furthermore, as well depth increases, early detection of gas intrusion becomes more challenging, significantly reducing well control time. Downhole monitoring methods are susceptible to downhole conditions, prone to distortion, and poorly adaptable to high-temperature and high-pressure environments.

[0004] Ultrasonic Doppler air intrusion monitoring technology is a non-invasive monitoring method, but current Doppler ultrasound technology has the following drawbacks: First, when there are two or more moving objects in the sampling volume, the echo signals reflected by these moving objects will be recorded, making it impossible to identify the source of the echo signal, lacking axial resolution, and unable to obtain fluid information at a specified location; Second, the ultrasonic signal first increases and then decreases with the increase of gas content, making it impossible to directly use ultrasonic characteristic parameters to determine the air intrusion state.

[0005] Therefore, a gas intrusion monitoring method that can overcome the above-mentioned technical defects is needed to improve the monitoring accuracy of downhole gas flow information, which is of great significance for the prevention and control of accidents such as well blowouts. Summary of the Invention

[0006] The purpose of this invention is to provide a gas intrusion monitoring device and method for wellbore, so as to obtain fluid information at a specified location and directly use ultrasonic features to determine the gas intrusion status.

[0007] To achieve the above objectives, embodiments of the present invention provide a gas intrusion monitoring device for a wellbore. The gas intrusion monitoring device includes: an ultrasonic transducer for transmitting pulsed ultrasonic waves into the annular pipe of the wellbore in a transmitting mode, wherein the pulsed ultrasonic waves are reflected by a moving scatterer at a predetermined position within the annular pipe and generate an echo signal; and receiving the echo signal in a receiving mode; a data processing device for processing the echo signal to obtain the Doppler amplitude of the echo signal; and a determination module for determining whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal.

[0008] Optionally, determining whether gas intrusion has occurred in the wellbore includes: determining the fluid flow pattern of the annulus pipe at the set position based on the Doppler amplitude of the echo signal; and determining whether gas intrusion has occurred in the wellbore based on the fluid flow pattern of the annulus pipe at the set position.

[0009] Optionally, determining the fluid flow pattern of the annular pipe at the set position includes: if the Doppler amplitude is less than a first threshold, determining the fluid flow pattern as bubble flow; if the Doppler amplitude is greater than the first threshold and less than a second threshold, determining the fluid flow pattern as plunger flow; and if the Doppler amplitude is greater than the second threshold, determining the fluid flow pattern as agitated flow.

[0010] Optionally, determining whether gas intrusion has occurred in the wellbore includes: if the ultrasonic transducer is a single ultrasonic transducer, and the fluid flow pattern is bubble flow, then the wellbore is determined not to have experienced gas intrusion; if the fluid flow pattern is plunger flow or agitation flow, then the wellbore is determined to have experienced gas intrusion; or if the ultrasonic transducer is a plurality of ultrasonic transducers, and the fluid flow pattern in the annular pipe at multiple predetermined positions is bubble flow, then the wellbore is determined not to have experienced gas intrusion; if the annular pipe at at least one predetermined position contains plunger flow or agitation flow, then the wellbore is determined to have experienced gas intrusion.

[0011] Optionally, in the event of gas intrusion in the wellbore, the determination module is further configured to determine the degree of gas intrusion in the wellbore based on the fluid flow pattern in the annular pipe at the set location. The determination of the degree of gas intrusion in the wellbore includes: if the ultrasonic transducer is a single ultrasonic transducer, and the fluid flow pattern is a plunger flow, then the wellbore is determined to have moderate gas intrusion; if the fluid flow pattern is a stirred flow, then the wellbore is determined to have severe gas intrusion. Alternatively, if the ultrasonic transducer is multiple ultrasonic transducers, if there is both bubble flow and plunger flow in the annular pipe, then the wellbore is determined to have moderate gas intrusion; if there is no bubble flow in the annular pipe, then the wellbore is determined to have severe gas intrusion.

[0012] Optionally, if there are multiple ultrasonic transducers, the multiple ultrasonic transducers are distributed at the bottom, middle and top of the wellbore.

[0013] Optionally, the ultrasonic transducer emits pulsed ultrasonic waves into the annular duct at a set incident angle in emission mode.

[0014] Optionally, the gas intrusion monitoring device further includes a control device for issuing pulse signal control commands, wherein the ultrasonic transducer switches between the transmission mode and the receiving mode at a set time interval according to the pulse signal control commands.

[0015] Optionally, the processing of the echo signal includes: extracting the Doppler signal from the echo signal using orthogonal demodulation technology; performing a short-time Fourier transform on the Doppler signal to obtain a Fourier time-frequency diagram; performing a wavelet transform on the Fourier spectrum in the Fourier time-frequency diagram to obtain an energy distribution spectrum in the time-frequency plane; and obtaining the Doppler amplitude of the echo signal from the energy distribution spectrum.

[0016] On the other hand, the present invention provides a method for monitoring gas intrusion in a wellbore. The method includes performing the following operations using an ultrasonic transducer: transmitting pulsed ultrasonic waves to the annular pipe of the wellbore in a transmitting mode, wherein the pulsed ultrasonic waves are reflected by a moving scatterer at a predetermined position within the annular pipe and generate an echo signal; and receiving the echo signal in a receiving mode; processing the echo signal to obtain the Doppler amplitude of the echo signal; and determining whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal.

[0017] Compared to existing technologies, the present invention, through the above-described technical solution, achieves excellent axial resolution. By setting the ultrasonic transducer and its position, information from a specified location can be acquired, enabling fluid measurement and extraction at that location. Furthermore, the solution of the present invention offers good timeliness and accuracy, allowing for timely monitoring and early warning in the event of gas intrusion, and extending well control time.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of a gas intrusion monitoring device for a wellbore according to an embodiment of the present invention;

[0021] Figures 2a-2b This is a schematic diagram of a bubble flow pattern according to an embodiment of the present invention;

[0022] Figures 3a-3b This is a schematic diagram of a plunger flow pattern according to an embodiment of the present invention;

[0023] Figures 4a-4b This is a schematic diagram of a stirred flow pattern according to an embodiment of the present invention;

[0024] Figures 5a-5cThis is a schematic diagram of fluid flow patterns at different locations within an annular pipe according to an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of a gas intrusion monitoring device for a wellbore according to an embodiment of the present invention;

[0026] Figure 7 This is a schematic flowchart of a gas intrusion monitoring method for wellbore according to an embodiment of the present invention;

[0027] Figure 8 This is a schematic diagram of a wellbore gas intrusion monitoring simulation device according to an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures

[0029] 100. Annular pipe; 200. Ultrasonic transducer; 300. Data processing device; 400. Judgment module;

[0030] 210. Ultrasonic testing instrument; 310. Digital instrument; 320. Computer. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0032] This invention provides a gas intrusion monitoring device for wellbores, such as... Figure 1 As shown. The gas intrusion monitoring device may include: an ultrasonic transducer 200, used to transmit pulsed ultrasonic waves to the annular pipe 100 of the wellbore in transmit mode, wherein the pulsed ultrasonic waves are reflected by a moving scatterer at a set position within the annular pipe 100 and generate an echo signal; and to receive the echo signal in receive mode; a data processing device 300, used to process the echo signal to obtain the Doppler amplitude of the echo signal; and a determination module 400, used to determine whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal.

[0033] in, Figure 1 The dashed lines in the diagram represent the ultrasonic transducer 200 transmitting and receiving pulsed ultrasonic waves to and from the annular pipe 100, while the solid lines represent the communication relationships between the ultrasonic transducer 200 and the data processing device 300, and between the data processing device 300 and the judgment module 400.

[0034] After the ultrasonic wave enters the annular pipe 100, the received echo signals differ due to the different acoustic intensity reflectivities between the gas and liquid phases. Therefore, the differences in moving scatterers can be distinguished based on the signal differences in the echo signals. Compared to the wave Doppler technology used in the prior art, this invention employs ultrasonic pulse Doppler. Through a self-transmitting and self-receiving ultrasonic transducer 200, ultrasonic waves can be emitted and received at certain time intervals; that is, it switches to receiving mode after emitting ultrasonic waves and to transmitting mode after receiving ultrasonic waves. Since the velocity of ultrasonic waves in the medium is relatively stable, by controlling the pulse repetition frequency, i.e., controlling the time interval between emitting and receiving ultrasonic waves, the echo signals of the desired measurement points can be selectively received (and the received echo signals do not overlap), thus achieving axial resolution. Simultaneously, this invention can acquire information at a specified location by setting the transducer position, enabling fluid measurement at a specified location to extract fluid information and obtain gas flow information at that location. Furthermore, this invention also has good timeliness and accuracy, enabling timely monitoring and early warning in the event of gas intrusion and increasing well control time.

[0035] In one embodiment, the ultrasonic transducer 200 can be installed on the outside of the annulus pipe 100, thereby avoiding any impact on the drilling fluid flow within the annulus pipe 100. Additionally, in transmission mode, the ultrasonic transducer 200 can emit pulsed ultrasonic waves into the annulus pipe 100 at a set incident angle. The purpose of setting the incident angle is to reduce the influence of the wellbore wall on the ultrasonic waves. These influences can be reduced by adjusting the incident angle depending on the wellbore wall material. Preferably, the incident angle is set to 30-60°.

[0036] In one embodiment, one or more ultrasonic transducers 200 can be configured. When using a single ultrasonic transducer, to achieve better detection results, the transducer 200 should be placed in the middle of the outer side of the well casing, thus balancing monitoring accuracy and timeliness. Preferably, when multiple ultrasonic transducers are used, at least one transducer should be located in the middle of the outer side of the well casing. For example, three ultrasonic transducers can be configured, distributed at the upper, middle, and bottom of the outer side of the well casing, respectively. The specific placement can be adjusted adaptively according to the needs of different application scenarios. For example, if the total length of the well casing is L, the distance L1 between the upper ultrasonic transducer and the top of the well casing can be set to 1 / 4-1 / 3L, the distance L2 between the middle ultrasonic transducer and the top of the well casing can be set to 1 / 3-2 / 3L, and the distance L3 between the bottom ultrasonic transducer and the top of the well casing can be set to 2 / 3-3 / 4L. More preferably, the distance between two adjacent ultrasonic transducers is not less than 1 / 6-1 / 4L.

[0037] In one embodiment, the determination module 400 may include: a fluid flow pattern determination module, used to determine the fluid flow pattern of the annulus pipe 100 at a set position based on the Doppler amplitude of the echo signal; and a gas intrusion determination module, used to determine whether gas intrusion has occurred in the wellbore based on the fluid flow pattern of the annulus pipe 100 at the set position.

[0038] In one embodiment, the fluid flow pattern determination module can be used to make the following determinations: if the Doppler amplitude is less than a first threshold, the fluid flow pattern is determined to be bubble flow; if the Doppler amplitude is greater than the first threshold and less than a second threshold, the fluid flow pattern is determined to be plunger flow; and if the Doppler amplitude is greater than the second threshold, the fluid flow pattern is determined to be stirred flow.

[0039] In principle, when gas intrusion occurs, gas enters the annular pipe and flows in a two-phase (gas-liquid) state. Therefore, the magnitude of the gas intrusion can be determined based on the fluid flow pattern. For example, phenomena such as... Figure 2a , 3a The three scenarios shown in 4a are bubble flow, plunger flow, and stirred flow. Among them, Figure 2a , 3a Image 4a is a real-life photo taken with a high-speed camera. Figure 2b , 3b Figure 4b is the time-frequency spectrum of the processed Doppler amplitude.

[0040] Specifically, Figure 2a The presence of small air bubbles with a diameter of approximately 5 mm in a pipe is called bubbly flow. In this case, it is generally considered a normal phenomenon of gas in the liquid and is not considered gas intrusion. Meanwhile... Figure 2b This indicates that the amplitude of the Doppler amplitude at the measured bubble location is at a low level.

[0041] Figure 3a Many small bubbles coalesced, forming large bubbles with a diameter close to the pipe's inner diameter, followed by numerous smaller bubbles; this phenomenon is called plug flow. At this point, the bubble velocity significantly increased, exhibiting a certain degree of gas intrusion. Figure 3b This indicates that the measured Doppler amplitude has also increased significantly.

[0042] Figure 4a The gas flow in the pipe becomes more chaotic, and the large bubbles appear more irregular in shape compared to those in plug flow. Smaller bubbles surround the larger bubbles, and there are many of them; this is called turbulent flow. At this point, it can be considered that significant gas intrusion has occurred. Figure 4b This indicates that the measured Doppler amplitude has also increased significantly.

[0043] It is worth noting that, due to different application scenarios, such as the influence of factors like liquid density, pipe diameter, ambient temperature, and ambient pressure, the threshold for determining the transition point of a specific fluid flow pattern (e.g., the first threshold from bubble flow to plunger flow, or the second threshold from plunger flow to stirred flow) is not the same. Those skilled in the art can adapt the threshold according to the actual application situation, and this invention does not impose any specific limitations on it.

[0044] In one embodiment, when the ultrasonic transducer 200 is a single ultrasonic transducer, it is preferably positioned in the middle of the outer side of the wellbore. If the fluid flow pattern is bubble flow, it is determined that no gas intrusion has occurred in the wellbore. If the fluid flow pattern is plunger flow or agitated flow, it is determined that gas intrusion has occurred in the wellbore.

[0045] In one embodiment, when there are multiple ultrasonic transducers 200, for example, three ultrasonic transducers are provided, such as... Figures 5a-5c As shown. Preferably, the plurality of ultrasonic transducers are positioned at the bottom, middle, and top of the outer side of the wellbore. If the fluid flow pattern in the annular pipe 100 at multiple predetermined locations is bubble flow (… Figure 5a If a plunger flow or agitation flow exists in at least one set location in the annulus pipe 100, it is determined that no gas intrusion has occurred in the wellbore. Figure 5b and Figure 5c If the gas intrusion occurs, it is determined that gas invasion has occurred in the wellbore.

[0046] In one embodiment, in the event of gas intrusion in the wellbore, the determination module 400 is further configured to determine the degree of gas intrusion in the wellbore based on the fluid flow pattern of the annular pipe 100 at a set position.

[0047] In one embodiment, when the ultrasonic transducer 200 is a single ultrasonic transducer, it is preferably positioned in the middle of the outer side of the wellbore. If the fluid flow pattern is plunger flow, moderate gas intrusion is determined to have occurred in the wellbore. If the fluid flow pattern is agitated flow, severe gas intrusion is determined to have occurred in the wellbore.

[0048] In one embodiment, when there are multiple ultrasonic transducers 200, for example, three ultrasonic transducers are provided, such as... Figure 5b and Figure 5c As shown. Preferably, the plurality of ultrasonic transducers are positioned at the bottom, middle, and top of the outer side of the wellbore. If bubble flow and plunger flow exist within the annular conduit 100 ( Figure 5b If there is no gas intrusion in the wellbore, it is determined that a moderate gas intrusion has occurred; if there is no gas bubble flow within the annular pipe 100 ( Figure 5c If the gas intrusion is detected, it is determined that the wellbore has experienced severe gas invasion.

[0049] In one embodiment, such as Figure 6As shown, the monitoring device may further include a control device for issuing pulse signal control commands, and the ultrasonic transducer 200 switches between a transmission mode and a reception mode at set time intervals according to the pulse signal control commands. Optionally, the control device may include a computer 320 and an ultrasonic detector 210, the computer 320 being used to control the ultrasonic detector 210 to issue pulse signal control commands.

[0050] In one embodiment, the data processing device 300 may further include a digitizing instrument 310 and a computer 320, wherein the digitizing instrument 310 is used to convert the echo signal into a digital signal, and the computer 320 is used to process the digital signal.

[0051] In one embodiment, processing the echo signal includes: extracting the Doppler signal from the echo signal using orthogonal demodulation technology; performing a short-time Fourier transform on the Doppler signal to obtain a Fourier time-frequency diagram; performing a wavelet transform on the Fourier spectrum in the Fourier time-frequency diagram to obtain an energy distribution spectrum in the time-frequency plane; and obtaining the Doppler amplitude of the echo signal from the energy distribution spectrum.

[0052] Due to the complex operating conditions during drilling, the received echo signals may contain various clutter. Therefore, it is necessary to perform orthogonal demodulation on the received echo signals. After orthogonal demodulation, the useful Doppler signal is extracted and subjected to short-time Fourier transform and empirical wavelet transform to obtain the energy distribution spectrum. For example, the Fourier spectrum of the Doppler echo signal can be adaptively segmented using the EWT algorithm to extract the single component containing the Doppler frequency shift. Then, a Hilbert transform is performed on the single component to obtain the energy distribution spectrum of the signal in the time-frequency plane. By observing the changes in Doppler amplitude and energy distribution, various flow patterns can be identified. In addition, using the Doppler frequency shift signal, pulse Doppler technology can detect the flow direction of the fluid at each location within the annular pipe 100, thereby determining the velocity vector of the fluid at that location. This velocity vector can be used to assist in verifying whether gas intrusion has occurred in the wellbore.

[0053] This invention also provides a method for monitoring gas intrusion in wellbores, such as... Figure 7 As shown. The gas intrusion monitoring method may include: S100, performing the following operations via an ultrasonic transducer: transmitting pulsed ultrasonic waves to the annular pipe in a transmitting mode, wherein the pulsed ultrasonic waves are reflected by a moving scatterer at a predetermined position within the annular pipe and generate the echo signal, and receiving the echo signal in a receiving mode; S200, processing the echo signal to obtain the Doppler amplitude of the echo signal; and S300, determining whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal.

[0054] After ultrasonic waves enter the annular pipe, the received echo signals differ due to the varying acoustic intensity reflectivity between the gas and liquid phases. Therefore, the differences in the echo signals can be used to distinguish the differences in moving scatterers. Compared to existing technologies, this invention employs ultrasonic pulse Doppler. Through a self-transmitting and self-receiving ultrasonic transducer, it can transmit and receive ultrasonic waves at specific time intervals; that is, it switches to receiving mode after transmitting ultrasonic waves and vice versa. Since the velocity of ultrasonic waves in the medium is relatively stable, by controlling the pulse repetition frequency—that is, controlling the time interval between transmitting and receiving ultrasonic waves—the echo signals from the desired measurement points can be selectively received (and the received echo signals do not overlap). Therefore, this invention can achieve axial resolution. Simultaneously, by setting the transducer position, information from a specified location can be acquired, enabling fluid measurement at a specified location to extract fluid information and obtain gas flow information at that location. Furthermore, this invention also has good timeliness and accuracy, allowing for timely monitoring and early warning in the event of gas intrusion and increasing well control time.

[0055] In one embodiment, the ultrasonic transducer can be installed outside the annulus pipe to avoid any impact on the drilling fluid flow within the annulus pipe. Furthermore, in transmission mode, the ultrasonic transducer can emit pulsed ultrasonic waves into the annulus pipe at a set incident angle. The purpose of setting the incident angle is to reduce the influence of the wellbore wall on the ultrasonic waves. These influences can be reduced by adjusting the incident angle depending on the wellbore wall material. Preferably, the incident angle is set to 30-60°.

[0056] In one embodiment, the ultrasonic transducer in step S100 can be one or more. When using a single ultrasonic transducer, to achieve better detection results, it should be placed in the middle of the outer side of the well casing, thus balancing monitoring accuracy and timeliness. When using multiple ultrasonic transducers, at least one should be located in the middle of the outer side of the well casing. Preferably, three ultrasonic transducers can be used, located at the upper, middle, and bottom of the outer side of the well casing, respectively.

[0057] In one embodiment, as shown in FIG4, a control device may be provided for issuing pulse signal control commands. The ultrasonic transducer 200 switches between a transmission mode and a reception mode at a set time interval according to the pulse signal control commands. Optionally, the control device may include a computer 320 and an ultrasonic detector 210, wherein the computer 320 is used to control the ultrasonic detector 210 to issue pulse signal control commands.

[0058] In one embodiment, a digitizing instrument 310 and a computer 320 may also be provided. The digitizing instrument 310 is used to convert the echo signal into a digital signal, and the computer 320 is used to process the digital signal.

[0059] In one embodiment, processing the echo signal S200 includes: S210, extracting the Doppler signal from the echo signal using orthogonal demodulation technology; S220, performing a short-time Fourier transform on the Doppler signal to obtain a Fourier time-frequency diagram; S230, performing an empirical wavelet transform on the Fourier spectrum in the Fourier time-frequency diagram to obtain an energy distribution spectrum in the time-frequency plane; and S240, obtaining the Doppler amplitude of the echo signal from the energy distribution spectrum.

[0060] Due to the complex operating conditions during drilling, the received echo signals may contain various clutter. Therefore, it is necessary to perform orthogonal demodulation on the received echo signals. After orthogonal demodulation, the useful Doppler signal is extracted and subjected to short-time Fourier transform to obtain the time-frequency diagram. For example, the Fourier spectrum of the Doppler echo signal can be adaptively segmented using the EWT algorithm to extract the single component containing the Doppler frequency shift. Then, a Hilbert transform is performed on the single component to obtain the energy distribution spectrum of the signal in the time-frequency plane. By observing the changes in Doppler amplitude and energy distribution, various flow patterns can be identified. In addition, using the Doppler frequency shift signal, pulsed Doppler technology can detect the flow direction of fluid at each location within the annulus pipe, thereby determining the velocity vector of the fluid at that location. This velocity vector can be used to assist in verifying whether gas intrusion has occurred in the wellbore.

[0061] In one embodiment, determining whether gas intrusion has occurred in the wellbore S300 may include: S310, determining the fluid flow pattern of the annulus pipe at a set position based on the Doppler amplitude of the echo signal; and S320, determining whether gas intrusion has occurred in the wellbore based on the fluid flow pattern of the annulus pipe at the set position.

[0062] In one embodiment, the determination of the fluid flow pattern S310 at the set position of the annular pipe may include: S311, if the Doppler amplitude is less than a first threshold, then the fluid flow pattern is determined to be bubble flow; S312, if the Doppler amplitude is greater than the first threshold and less than a second threshold, then the fluid flow pattern is determined to be plunger flow; and S313, if the Doppler amplitude is greater than the second threshold, then the fluid flow pattern is determined to be agitated flow.

[0063] In one embodiment, the determination of whether gas intrusion has occurred in the wellbore S320 may include: S321, when the ultrasonic transducer is a single ultrasonic transducer (preferably the ultrasonic transducer is located in the middle of the outer side of the wellbore), if the fluid flow pattern is bubble flow, it is determined that gas intrusion has not occurred in the wellbore; if the fluid flow pattern is plunger flow or agitation flow, it is determined that gas intrusion has occurred in the wellbore.

[0064] In one embodiment, the determination of whether gas intrusion has occurred in the wellbore S320 may further include: S322, in the case of multiple ultrasonic transducers (e.g., three ultrasonic transducers are provided, such as...). Figures 5a-5c As shown. Preferably, the plurality of ultrasonic transducers are positioned at the bottom, middle, and top of the outer side of the wellbore. If the fluid flow pattern in the annular pipe at multiple predetermined locations is bubble flow (…), Figure 5a If gas intrusion has occurred in the wellbore, it is determined that no gas intrusion has occurred; if a plunger flow or agitation flow exists in the annulus pipe at at least one set location ( Figure 5b and Figure 5c If the gas intrusion occurs, it is determined that gas invasion has occurred in the wellbore.

[0065] In one embodiment, in the event of gas intrusion in the wellbore, the gas intrusion monitoring method may further include: S400, determining the degree of gas intrusion in the wellbore based on the fluid flow pattern of the annulus pipe at a set location.

[0066] In one embodiment, the determination of the degree of gas intrusion in the wellbore S400 may include: S401, when the ultrasonic transducer is a single ultrasonic transducer (preferably the ultrasonic transducer is located in the middle of the outer side of the wellbore), if the fluid flow pattern is plunger flow, then the wellbore is determined to have moderate gas intrusion; if the fluid flow pattern is agitated flow, then the wellbore is determined to have severe gas intrusion.

[0067] In one embodiment, the determination of the degree of gas intrusion in the wellbore S400 may further include: S402, in the case of multiple ultrasonic transducers (e.g., three ultrasonic transducers are provided, such as...) Figure 5b and Figure 5c As shown. Preferably, the plurality of ultrasonic transducers are positioned at the bottom, middle, and top of the outer side of the wellbore. If bubble flow and plunger flow exist within the annular pipe... Figure 5b If there is no gas ingress in the wellbore, it is determined that a moderate gas intrusion has occurred; if there is no gas bubble flow in the annulus pipe ( Figure 5c If the gas intrusion is detected, it is determined that the wellbore has experienced severe gas invasion.

[0068] In summary, the gas intrusion monitoring device and method for wellbore provided by this invention employs pulse Doppler technology, which can not only monitor the flow velocity of gas-liquid two-phase flow but also acquire fluid information at a specified location in real time, enabling real-time monitoring of the gas content and flow pattern of gas intrusion in the well. Furthermore, it only requires the installation of a single ultrasonic transducer to achieve both transmission and reception functions, resulting in relatively low cost and adaptability to most environments.

[0069] To further illustrate the present invention, the following description is provided. Figure 8 An embodiment is provided to simulate the gas intrusion monitoring device of the present invention.

[0070] like Figure 8The system shown includes: a drilling fluid pool, a water tank, a pump, an annular pipe, ultrasonic transducers (1, 2, 3), an ultrasonic testing instrument, digital instruments, a computer, an air compressor, and gas and liquid flow meters. The annular pipe consists of drill pipe and wellbore wall. Drilling fluid from the drilling fluid pool is injected into the annular pipe via a pump to simulate the working environment of a real drill pipe.

[0071] In addition, a gas intrusion simulation device is composed of an air compressor, a water tank, a gas flow meter, a liquid flow meter, and a bubble pulverizer. The gas flow meter can control the rate at which the air compressor injects gas to simulate gas intrusion occurring under underbalanced conditions and different degrees of gas intrusion.

[0072] Three ultrasonic transducers can be installed, at the bottom, middle, and top of the outer side of the well casing. The computer can control the ultrasonic detector to send pulse signal control commands. The ultrasonic transducers emit pulse waves with an incident angle of 45° into the annular pipe according to the pulse signal control commands. Then, the ultrasonic transducers switch to receiving mode to receive the echo signals. The digital instrument converts the echo signals into digital signals and stores them in the computer.

[0073] The drilling process involves complex conditions, and the received echo signals contain various clutter. Therefore, orthogonal demodulation is first used to demodulate the received echo signals and extract the Doppler signal. After orthogonal demodulation, the useful Doppler signal is extracted and subjected to a short-time Fourier transform to obtain the Fourier time-frequency plot. Then, a wavelet transform (e.g., empirical wavelet transform) is performed on the Fourier spectrum in the Fourier time-frequency plot to obtain the energy distribution spectrum in the time-frequency plane. Finally, the Doppler amplitude of the echo signal is obtained from the energy distribution spectrum.

[0074] By combining the changes in the time-frequency spectrum, and observing the changes in Doppler amplitude and energy distribution, various flow patterns can be identified. Combined with the air intrusion monitoring method described above in this invention, the occurrence and degree of air intrusion can be measured and verified in real time.

[0075] Simulation tests have shown that the gas intrusion monitoring method of this invention can identify different types of gas intrusion in a timely and accurate manner. It is evident that the gas intrusion monitoring device and method of this invention have excellent timeliness and accuracy in the oil and gas drilling field, significantly improving the monitoring precision of downhole gas flow information. Therefore, it has significant technical advantages and is of great importance for the prevention and control of accidents such as well blowouts.

[0076] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0077] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A gas invasion monitoring device for a wellbore, applied to early gas invasion monitoring in the drilling process of oil and gas well development, characterized in that, The air intrusion monitoring device includes: An ultrasonic transducer is used to transmit pulsed ultrasonic waves into the annular pipe of the wellbore in a transmitting mode. The pulsed ultrasonic waves are reflected by a moving scatterer at a set position within the annular pipe, generating an echo signal. In a receiving mode, the echo signal is received. The echo signal is selectively received from desired measurement points by controlling the pulse repetition frequency of the pulsed ultrasonic waves and the time interval between transmitting and receiving the ultrasonic waves, thereby achieving axial resolution. Furthermore, based on the position of the transducer, fluid information can be extracted from the set position to obtain gas flow information at that location. A data processing device is configured to process the echo signal to obtain the Doppler amplitude of the echo signal; and The determination module is used to determine whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal. In the case where there are multiple ultrasonic transducers, the multiple ultrasonic transducers are distributed at the bottom, middle and top of the outer side of the wellbore. The determination of whether gas intrusion has occurred in the wellbore includes: if the fluid flow pattern in the annular pipe at multiple predetermined locations is bubble flow, then the wellbore is determined not to have experienced gas intrusion; if the annular pipe at at least one predetermined location contains plunger flow or agitated flow, then the wellbore is determined to have experienced gas intrusion. In the event of gas intrusion in the wellbore, the determination module is further configured to determine the degree of gas intrusion based on the fluid flow pattern in the annular pipe at the set location. The determination of the degree of gas intrusion in the wellbore includes: if bubble flow and plunger flow exist in the annulus, the wellbore is determined to have moderate gas intrusion; if no bubble flow exists in the annulus, the wellbore is determined to have severe gas intrusion. The gas intrusion monitoring device further includes a control device for issuing pulse signal control commands, and the ultrasonic transducer switches between the transmission mode and the receiving mode at a set time interval according to the pulse signal control commands.

2. The gas intrusion monitoring device of a wellbore of claim 1, wherein, The determination of whether gas intrusion has occurred in the wellbore includes: Based on the Doppler amplitude of the echo signal, the fluid flow pattern in the annular pipe at the set location is determined; and Based on the fluid flow pattern of the annular pipe at the set location, it is determined whether gas intrusion has occurred in the wellbore.

3. The gas intrusion monitoring device for wellbore according to claim 2, characterized in that, The determination of the fluid flow pattern in the annular pipe at the set position includes: If the Doppler amplitude is less than the first threshold, the fluid flow pattern is determined to be bubble flow; If the Doppler amplitude is greater than the first threshold and less than the second threshold, then the fluid flow pattern is determined to be plug flow; and If the Doppler amplitude is greater than the second threshold, the fluid flow pattern is determined to be a stirred flow.

4. The gas intrusion monitoring device of a wellbore of any one of claims 1-3, wherein, In the transmission mode, the ultrasonic transducer emits pulsed ultrasonic waves at a set incident angle into the annular duct.

5. The gas intrusion monitoring device of a wellbore of any one of claims 1-3, wherein, The processing of the echo signal includes: The Doppler signal is extracted from the echo signal using orthogonal demodulation technology; Perform a short-time Fourier transform on the Doppler signal to obtain a Fourier time-frequency diagram; Perform wavelet transform on the Fourier spectrum in the Fourier time-frequency plot to obtain the energy distribution spectrum in the time-frequency plane; and The Doppler amplitude of the echo signal is obtained from the energy distribution spectrum.

6. A method for gas invasion monitoring of a wellbore, applied to early gas invasion monitoring in the drilling process of oil and gas well development, characterized in that, The gas intrusion monitoring method includes: The ultrasonic transducer performs the following operations: in transmit mode, it transmits pulsed ultrasonic waves into the annular pipe of the wellbore; the pulsed ultrasonic waves are reflected by a moving scatterer at a set position within the annular pipe, generating an echo signal; and in receive mode, it receives the echo signal. The echo signal is selectively received from desired measurement points by controlling the pulse repetition frequency of the pulsed ultrasonic waves and the time interval between transmitting and receiving the ultrasonic waves, thereby achieving axial resolution. Furthermore, based on the position of the transducer, fluid at the set position can be measured to extract fluid information and obtain gas flow information at the set position. The echo signal is processed to obtain the Doppler amplitude of the echo signal; and Based on the Doppler amplitude of the echo signal, it is determined whether gas intrusion has occurred in the wellbore. In the case where there are multiple ultrasonic transducers, the multiple ultrasonic transducers are distributed at the bottom, middle and top of the outer side of the wellbore. The determination of whether gas intrusion has occurred in the wellbore includes: if the fluid flow pattern in the annular pipe at multiple predetermined locations is bubble flow, then the wellbore is determined not to have experienced gas intrusion; if the annular pipe at at least one predetermined location contains plunger flow or agitated flow, then the wellbore is determined to have experienced gas intrusion. In the event of gas intrusion in the wellbore, the gas intrusion monitoring method further includes: determining the degree of gas intrusion in the wellbore based on the fluid flow pattern in the annular pipe at the set location. The determination of the degree of gas intrusion in the wellbore includes: if bubble flow and plunger flow exist in the annulus, the wellbore is determined to have moderate gas intrusion; if no bubble flow exists in the annulus, the wellbore is determined to have severe gas intrusion. The gas intrusion monitoring method further includes: issuing a pulse signal control command, causing the ultrasonic transducer to switch between the transmission mode and the receiving mode at a set time interval according to the pulse signal control command.

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