Wellbore gas kick monitoring apparatus and method

Abstract

A wellbore gas kick monitoring apparatus comprises: an ultrasonic transducer (200) used for, when in an emitting mode, emitting pulse ultrasonic waves to an annulus (100) in a wellbore, and used for, when in a receiving mode, receiving echo signals generated by the pulse ultrasonic waves reflected by a moving scatterer in a set position in the annulus (100); a data processing apparatus (300) used for processing the echo signals to obtain the Doppler amplitude thereof; and a determining module (400) used for determining, according to the Doppler amplitude of the echo signals, whether a gas kick has occurred in the wellbore. The present gas kick monitoring apparatus has good axial resolution, measures fluid at designated positions to extract fluid information, and when a gas kick occurs, conducts monitoring and issues early warnings in a timely manner, and prolongs well control time. Also provided is a wellbore gas kick monitoring method.

Description

Wellbore gas intrusion monitoring device and method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202310671506.4 filed on June 7, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of oil and gas drilling, and in particular to a gas intrusion monitoring device and method for a wellbore. Background Art

[0004] As the geological conditions for oil and gas well development become increasingly complex, drilling is prone to encountering abnormally high-pressure formations, leading to gas intrusion and various drilling safety accidents such as blowouts, which pose a significant threat to worker safety and environmental protection. Therefore, the prevention and control of accidents such as blowouts are becoming increasingly important in the drilling process.

[0005] If gas intrusion occurs during drilling, it's difficult to detect in its initial stages using monitoring methods like fluid increments in the drilling fluid pool or flow differential overflow. Furthermore, as wellhead depth increases, early detection of gas intrusion becomes increasingly difficult, significantly reducing well control time. Downhole monitoring while drilling (MWD) methods are susceptible to interference from downhole conditions, prone to distortion, and poor adaptability to high-temperature, high-pressure environments.

[0006] Ultrasonic Doppler gas intrusion monitoring technology is a non-invasive monitoring method, but the current Doppler ultrasonic technology has the following disadvantages: First, when two or more moving objects appear in the sampling volume, the echo signals reflected by these moving objects will be recorded, resulting in the inability to confirm the source of the echo signal, lack of axial resolution, and inability to obtain fluid information at a specified location; second, the ultrasonic signal first increases and then decreases with the increase of gas fraction, resulting in the inability to directly use ultrasonic characteristic parameters to judge the gas intrusion status.

[0007] Therefore, a gas intrusion monitoring method that can solve the above 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 blowouts.

[0008] Summary of the Invention

[0009] The purpose of the embodiments of the present application is to provide a gas intrusion monitoring device and method for a wellbore, so as to obtain fluid information at a specified location and directly determine the gas intrusion status using ultrasonic characteristics.

[0010] In order to achieve the above-mentioned purpose, an embodiment of the present application provides a gas intrusion monitoring device for a wellbore, wherein the gas intrusion monitoring device includes: an ultrasonic transducer for emitting pulsed ultrasonic waves to the annular pipe of the wellbore in a transmitting mode, wherein the pulsed ultrasonic waves are reflected when encountering a mobile scatterer at a set position in 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 judgment module for judging whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal.

[0011] Optionally, determining whether gas intrusion occurs in the wellbore includes: determining the fluid flow pattern of the annular pipe at the set position based on the Doppler amplitude of the echo signal; and determining whether gas intrusion occurs in the wellbore based on the fluid flow pattern of the annular pipe at the set position.

[0012] Optionally, determining the fluid flow type of the annular pipe at the set position includes: if the Doppler amplitude is less than a first threshold, determining that the fluid flow type is a bubble flow; if the Doppler amplitude is greater than the first threshold and less than a second threshold, determining that the fluid flow type is a plunger flow; and if the Doppler amplitude is greater than the second threshold, determining that the fluid flow type is a stirring flow.

[0013] Optionally, the determining whether gas intrusion has occurred in the wellbore includes: when the ultrasonic transducer is one ultrasonic transducer, if the fluid flow type is bubble flow, determining that gas intrusion has not occurred in the wellbore; if the fluid flow type is plunger flow or stirring flow, determining that gas intrusion has occurred in the wellbore; or when the ultrasonic transducer is multiple ultrasonic transducers, if the fluid flow type of the annular pipe at multiple set positions is bubble flow, determining that gas intrusion has not occurred in the wellbore; if there is plunger flow or stirring flow in at least one set position of the annular pipe, determining that gas intrusion has occurred in the wellbore.

[0014] Optionally, in the event that gas invasion occurs in the wellbore, the determination module is further used to determine the degree of gas invasion in the wellbore based on the fluid flow pattern of the annular pipe at the set position. The determination of the degree of gas invasion in the wellbore includes: when the ultrasonic transducer is a single ultrasonic transducer, if the fluid flow pattern is a plunger flow, it is determined that moderate gas invasion has occurred in the wellbore; if the fluid flow pattern is a stirring flow, it is determined that severe gas invasion has occurred in the wellbore; or when the ultrasonic transducer is a plurality of ultrasonic transducers, if there is a bubble flow and a plunger flow in the annular pipe, it is determined that moderate gas invasion has occurred in the wellbore; if there is no bubble flow in the annular pipe, it is determined that severe gas invasion has occurred in the wellbore.

[0015] Optionally, when the ultrasonic transducer is a plurality of ultrasonic transducers, the plurality of ultrasonic transducers are distributed at the bottom, middle and upper parts of the wellbore.

[0016] Optionally, the ultrasonic transducer transmits pulsed ultrasonic waves to the annular pipe at a set incident angle in a transmitting mode.

[0017] Optionally, the gas intrusion monitoring device further includes a control device for issuing a pulse signal control instruction, and the ultrasonic transducer switches between the transmitting mode and the receiving mode at a set time interval according to the pulse signal control instruction.

[0018] Optionally, the processing of the echo signal includes: extracting a 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 diagram on the time-frequency plane; and obtaining the Doppler amplitude of the echo signal from the energy distribution spectrum diagram.

[0019] On the other hand, the present application provides a method for monitoring gas intrusion in a wellbore, which includes: performing the following operations through 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 mobile scatterer at a set position in the annular pipe and generate the 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.

[0020] Compared to existing technologies, the present invention achieves excellent axial resolution through the above-mentioned technical solution. By setting the ultrasonic transducer and adjusting its position, information can be acquired at a specific location, enabling fluid measurement at the specified location and extracting fluid information. Furthermore, the present invention's solution also offers excellent timeliness and accuracy, enabling timely monitoring and early warning when gas intrusion occurs, thereby increasing well control time.

[0021] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present application but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0023] FIG1 is a schematic diagram of a gas intrusion monitoring device for a wellbore according to an embodiment of the present application;

[0024] 2a-2b are schematic diagrams showing a fluid flow pattern of bubble flow according to an embodiment of the present application;

[0025] 3a-3b are schematic diagrams showing a fluid flow pattern of plunger flow according to an embodiment of the present application;

[0026] 4a-4b are schematic diagrams showing a fluid flow pattern of stirring flow according to an embodiment of the present application;

[0027] 5a-5c are schematic diagrams of fluid flow patterns at different positions within an annular pipe according to an embodiment of the present application;

[0028] FIG6 is a schematic diagram of a gas intrusion monitoring device for a wellbore according to an embodiment of the present application;

[0029] FIG7 is a flow chart of a method for monitoring gas intrusion in a wellbore according to an embodiment of the present application;

[0030] FIG8 is a schematic diagram of a wellbore gas intrusion monitoring simulation device according to an embodiment of the present application.

[0031] DESCRIPTION OF REFERENCE NUMERALS 100 , annular pipe; 200 , ultrasonic transducer; 300 , data processing device; 400 , determination module; 210 , ultrasonic detector; 310 , digitizing instrument; 320 , computer. DETAILED DESCRIPTION

[0032] The following describes the specific implementation of the embodiment of the present application in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present application and is not intended to limit the embodiment of the present application.

[0033] The present application provides a gas intrusion monitoring device for a wellbore, as shown in FIG1 . The gas intrusion monitoring device may include: an ultrasonic transducer 200 for transmitting pulsed ultrasonic waves toward an annular pipe 100 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 100 and generate an echo signal; and a transducer for receiving the echo signal in a receiving mode; a data processing device 300 for processing the echo signal to obtain the Doppler amplitude of the echo signal; and a determination module 400 for determining whether gas intrusion has occurred in the wellbore based on the Doppler amplitude of the echo signal.

[0034] 1 indicates that the ultrasonic transducer 200 transmits and receives pulsed ultrasonic waves to the annular pipe 100 , and the solid line indicates the communication relationship between the ultrasonic transducer 200 and the data processing device 300 , and between the data processing device 300 and the determination module 400 .

[0035] After the ultrasonic wave enters the annular pipe 100, the echo signals received are different due to the different acoustic intensity reflectivity between the gas and liquid phases. Therefore, the difference in the moving scatterers can be distinguished based on the signal difference of the echo signals. Compared with the wave Doppler technology used in the prior art, the present application adopts ultrasonic pulse Doppler. Through the self-transmitting and self-receiving ultrasonic transducer 200, it can transmit and receive ultrasonic waves at a certain time interval, that is, it switches to the receiving mode after transmitting the ultrasonic wave and switches to the transmitting mode after receiving the ultrasonic wave. Since the speed 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, it is possible to selectively receive the echo signals of the required measurement points (and the received echo signals do not overlap), so it can have axial resolution. At the same time, the present application can achieve the acquisition of information at a specified location by setting the position of the transducer, and can measure the fluid at the specified location and then extract fluid information, and obtain information about the gas flow at the specified location. In addition, the present application also has good timeliness and accuracy, and can timely monitor and warn when gas invasion occurs and increase well control time.

[0036] In one embodiment, the ultrasonic transducer 200 can be installed outside the annular pipe 100 to avoid any impact on the drilling fluid within the annular pipe 100. Furthermore, in transmit mode, the ultrasonic transducer 200 can emit pulsed ultrasonic waves into the annular pipe 100 at a set angle of incidence. This angle of incidence serves to reduce the impact of the wellbore wall on the ultrasonic waves. These impacts can be minimized by adjusting the angle of incidence based on the wellbore wall material. Preferably, the angle of incidence is set to 30-60°.

[0037] In one embodiment, one or more ultrasonic transducers 200 may be provided. When a single ultrasonic transducer is provided, for optimal detection, it should be placed in the middle of the wellbore's exterior. This ensures both accuracy and timeliness of monitoring. Preferably, when multiple ultrasonic transducers are provided, at least one should be located in the middle of the wellbore's exterior. For example, three ultrasonic transducers may be provided, located at the top, middle, and bottom of the wellbore. The specific placement can be adjusted adaptively based on the needs of different application scenarios. For example, if the total length of the wellbore is L, the distance L1 from the top ultrasonic transducer to the wellbore's top can be set to 1 / 4-1 / 3L, the distance L2 from the middle ultrasonic transducer to the wellbore's top can be set to 1 / 3-2 / 3L, and the distance L3 from the bottom ultrasonic transducer to the wellbore's top can be set to 2 / 3-3 / 4L. More preferably, the distance between two adjacent ultrasonic transducers is no less than 1 / 6-1 / 4L.

[0038] In one embodiment, the determination module 400 may include: a fluid flow pattern determination module, used to determine the fluid flow pattern of the annular 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 occurs in the wellbore based on the fluid flow pattern of the annular pipe 100 at a set position.

[0039] In one embodiment, the fluid flow type determination module can be used to make the following determinations: if the Doppler amplitude is less than a first threshold, the fluid flow type is determined to be a bubble flow; if the Doppler amplitude is greater than the first threshold and less than a second threshold, the fluid flow type is determined to be a plug flow; and if the Doppler amplitude is greater than the second threshold, the fluid flow type is determined to be a stirring flow.

[0040] In principle, when gas intrusion occurs, gas invades the annular pipe and exhibits a gas-liquid two-phase flow state. Therefore, the amount of gas intrusion can be determined based on the fluid flow pattern. For example, three scenarios may occur, as shown in Figures 2a, 3a, and 4a: bubble flow, plunger flow, and stirring flow. Figures 2a, 3a, and 4a are actual images captured by a high-speed camera, while Figures 2b, 3b, and 4b are processed Doppler amplitude time-frequency spectra.

[0041] Specifically, Figure 2a shows the presence of small, dispersed bubbles with a diameter of approximately 5 mm in the pipe, known as bubbly flow. This is generally considered a normal phenomenon of gas in the liquid and is not considered to be a gas intrusion. Figure 2b also indicates that the Doppler amplitude measured at the bubble location is relatively low.

[0042] Figure 3a shows the aggregation of many small bubbles, forming a large bubble with a diameter close to the inner diameter of the pipe, followed by many smaller bubbles. This is known as plug flow. The bubble velocity increases significantly, indicating a certain degree of gas intrusion. Figure 3b also shows a significant increase in the measured Doppler amplitude.

[0043] Figure 4a shows that the gas flow in the pipeline has become more chaotic. The large bubbles appear irregular in shape compared to those in plug flow. Smaller bubbles surround the larger bubbles and are numerous, a phenomenon known as stirring flow. This indicates clear gas intrusion. Figure 4b also indicates a significant increase in the measured Doppler amplitude.

[0044] It is worth noting that due to different application scenarios, such as the influence of factors such as liquid density, pipe diameter, ambient temperature, ambient pressure, etc., the transition nodes for determining a specific fluid flow type (for example, the first threshold from bubble flow to plunger flow, or the second threshold from plunger flow to stirring flow) are not the same. Those skilled in the art can adaptively set them according to actual application conditions, and this application does not make specific limitations on this.

[0045] In one embodiment, when 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 plug flow or stirring flow, it is determined that gas intrusion has occurred in the wellbore.

[0046] In one embodiment, when the ultrasonic transducer 200 is a plurality of ultrasonic transducers, for example, three ultrasonic transducers are provided, as shown in Figures 5a-5c. In this case, the plurality of ultrasonic transducers are preferably provided at the bottom, middle, and upper portions of the outer side of the wellbore. If the fluid flow pattern of the annular pipe 100 at multiple set positions is bubble flow (Figure 5a), it is determined that no gas intrusion has occurred in the wellbore. If the annular pipe 100 has plug flow or stirring flow in at least one set position (Figures 5b and 5c), it is determined that gas intrusion has occurred in the wellbore.

[0047] In one embodiment, when gas invasion occurs in the wellbore, the determination module 400 is further configured to determine the extent of the gas invasion in the wellbore based on the fluid flow pattern of the annular pipe 100 at a set position.

[0048] In one embodiment, when 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 plug flow, moderate gas intrusion is determined to have occurred in the wellbore. If the fluid flow pattern is stirring flow, severe gas intrusion is determined to have occurred in the wellbore.

[0049] In one embodiment, when the ultrasonic transducer 200 comprises multiple ultrasonic transducers, for example, three ultrasonic transducers are provided, as shown in Figures 5b and 5c. In this case, the multiple ultrasonic transducers are preferably positioned at the bottom, middle, and upper portions of the wellbore. If bubble flow and plunger flow are present within the annular pipe 100 (Figure 5b), moderate gas intrusion is determined to have occurred in the wellbore. If bubble flow is absent within the annular pipe 100 (Figure 5c), severe gas intrusion is determined to have occurred in the wellbore.

[0050] In one embodiment, as shown in FIG6 , the monitoring device may further include a control device configured to issue pulse signal control instructions, whereby the ultrasonic transducer 200 switches between a transmitting mode and a receiving mode at set time intervals according to the pulse signal control instructions. Optionally, the control device may include a computer 320 and an ultrasonic detector 210 , wherein the computer 320 is configured to control the ultrasonic detector 210 to issue the pulse signal control instructions.

[0051] In one embodiment, the data processing device 300 may further include a digitizer 310 and a computer 320 . The digitizer 310 is used to convert the echo signal into a digital signal, and the computer 320 is used to process the digital signal.

[0052] 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 diagram on the time-frequency plane; and obtaining the Doppler amplitude of the echo signal from the energy distribution spectrum diagram.

[0053] Due to the complex drilling process, the received echo signal may contain various clutters. Therefore, it is necessary to perform orthogonal demodulation on the received echo signal. After orthogonal demodulation, the useful Doppler signal is extracted and subjected to short-time Fourier transform and empirical wavelet transform to obtain an energy distribution spectrum. For example, the Fourier spectrum of the Doppler echo signal can be adaptively segmented using the EWT algorithm to extract a single component containing the Doppler frequency shift. This single component is then subjected to a Hilbert transform to obtain an energy distribution spectrum of the signal on the time-frequency plane. By observing changes in the 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.

[0054] The present application also provides a method for monitoring gas intrusion in a wellbore, as shown in FIG7 . The method may include: S100, using an ultrasonic transducer to perform the following operations: transmitting a pulse ultrasonic wave to the annular pipe in a transmitting mode, wherein the pulse ultrasonic wave is reflected by a mobile scatterer at a predetermined position in the annular pipe and generates the echo signal; and receiving the echo signal in a receiving mode; S200, processing the echo signal to obtain a 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.

[0055] After the ultrasonic wave enters the annular pipe, the echo signals received are different due to the different sound intensity reflectivity between the gas and liquid phases. Therefore, the difference in the moving scatterers can be distinguished based on the signal difference of the echo signal. Compared with the prior art, the present application adopts ultrasonic pulse Doppler, which can transmit and receive ultrasonic waves at a certain time interval through a self-transmitting and self-receiving ultrasonic transducer, that is, it switches to a receiving mode after transmitting the ultrasonic wave and switches to a transmitting mode after receiving the ultrasonic wave. Since the speed 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 of the required measurement points can be selectively received (and the received echo signals do not overlap), so the present application can have axial resolution. At the same time, by setting the position of the transducer, the information of the specified position can be obtained, the fluid at the specified position can be measured and the fluid information can be extracted, and the information of the gas flow at the specified position can be obtained. In addition, the present application also has good timeliness and accuracy, and can timely monitor and warn when gas invasion occurs and increase the well control time.

[0056] In one embodiment, the ultrasonic transducer can be mounted outside the annular pipe to avoid any impact on the drilling fluid within the annular pipe. Furthermore, in transmit mode, the ultrasonic transducer can emit pulsed ultrasonic waves into the annular pipe at a set angle of incidence. This angle of incidence is intended to reduce the impact of the wellbore wall on the ultrasonic waves. These impacts can be minimized by adjusting the angle of incidence based on the wellbore wall material. Preferably, the angle of incidence is set to 30-60°.

[0057] In one embodiment, the ultrasonic transducer in step S100 can be provided as one or more ultrasonic transducers. When a single ultrasonic transducer is provided, to achieve optimal detection, it should be placed in the middle of the wellbore exterior, thereby ensuring both accuracy and timeliness of monitoring. When multiple ultrasonic transducers are provided, at least one ultrasonic transducer should be located in the middle of the wellbore exterior. Preferably, three ultrasonic transducers can be provided, located at the top, middle, and bottom of the wellbore exterior, respectively.

[0058] In one embodiment, as shown in FIG4 , a control device may be provided for issuing pulse signal control instructions, and the ultrasonic transducer 200 switches between a transmitting mode and a receiving mode at set time intervals according to the pulse signal control instructions. Optionally, the control device may include a computer 320 and an ultrasonic detector 210, with the computer 320 controlling the ultrasonic detector 210 to issue the pulse signal control instructions.

[0059] In one embodiment, a digitizer 310 and a computer 320 may be further provided. The digitizer 310 is used to convert the echo signal into a digital signal, and the computer 320 is used to process the digital signal.

[0060] In one embodiment, processing the echo signal S200 includes: S210, using orthogonal demodulation technology to extract the Doppler signal from the echo signal; 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 diagram on the time-frequency plane; and S240, obtaining the Doppler amplitude of the echo signal from the energy distribution spectrum diagram.

[0061] Due to the complex drilling process, the received echo signal may contain various clutters. Therefore, the received echo signal needs to be orthogonally demodulated. After orthogonal demodulation, the useful Doppler signal is extracted and then subjected to a short-time Fourier transform to obtain a time-frequency diagram. For example, the EWT algorithm can be used to adaptively segment the Fourier spectrum of the Doppler echo signal, extracting a single component containing the Doppler frequency shift. This single component is then subjected to a Hilbert transform to obtain an energy distribution spectrum of the signal on the time-frequency plane. By observing changes in the Doppler amplitude and energy distribution, various flow patterns can be identified. Furthermore, using the Doppler frequency shift signal, pulse Doppler technology can detect the flow direction of the fluid at each location within the annular 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.

[0062] In one embodiment, determining whether gas invasion occurs in the wellbore S300 may include: S310, determining a fluid flow pattern in the annular pipe at a set position based on the Doppler amplitude of the echo signal; and S320, determining whether gas invasion occurs in the wellbore based on the fluid flow pattern in the annular pipe at the set position.

[0063] In one embodiment, the step S310 of determining the fluid flow type of the annular pipe at a set position may include: S311, if the Doppler amplitude is less than a first threshold, determining that the fluid flow type is a bubble flow; S312, if the Doppler amplitude is greater than the first threshold and less than a second threshold, determining that the fluid flow type is a plug flow; and S313, if the Doppler amplitude is greater than the second threshold, determining that the fluid flow type is a stirring flow.

[0064] In one embodiment, the determining 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 disposed in the middle of the outer side of the wellbore), if the fluid flow pattern is a bubble flow, determining that gas intrusion has not occurred in the wellbore; if the fluid flow pattern is a plunger flow or a stirring flow, determining that gas intrusion has occurred in the wellbore.

[0065] In one embodiment, the determining whether gas invasion has occurred in the wellbore S320 may further include: S322, in the case where the ultrasonic transducer is a plurality of ultrasonic transducers (for example, three ultrasonic transducers are provided, as shown in Figures 5a-5c. In this case, the plurality of ultrasonic transducers are preferably provided at the bottom, middle, and upper portions of the outside of the wellbore), if the fluid flow pattern of the annular pipe at a plurality of set positions is bubble flow (Figure 5a), it is determined that gas invasion has not occurred in the wellbore; if there is a plunger flow or a stirring flow in at least one set position of the annular pipe (Figures 5b and 5c), it is determined that gas invasion has occurred in the wellbore.

[0066] In one embodiment, when gas invasion occurs in the wellbore, the gas invasion monitoring method may further include: S400, determining the extent of gas invasion in the wellbore according to the fluid flow pattern of the annular pipe at a set position.

[0067] In one embodiment, the step S400 of determining the extent of gas invasion in the wellbore may include: S401, when the ultrasonic transducer is a single ultrasonic transducer (preferably, the ultrasonic transducer is disposed in the middle of the outer side of the wellbore), if the fluid flow pattern is a plug flow, determining that moderate gas invasion has occurred in the wellbore; if the fluid flow pattern is a stirring flow, determining that severe gas invasion has occurred in the wellbore.

[0068] In one embodiment, the determination of the degree of gas invasion in the wellbore S400 may further include: S402, when the ultrasonic transducer is a plurality of ultrasonic transducers (for example, three ultrasonic transducers are provided, as shown in FIG5b and FIG5c. In this case, the plurality of ultrasonic transducers are preferably provided at the bottom, middle, and upper portions of the outside of the wellbore), if bubble flow and plunger flow exist in the annular pipe (FIG5b), it is determined that moderate gas invasion has occurred in the wellbore; if bubble flow does not exist in the annular pipe (FIG5c), it is determined that severe gas invasion has occurred in the wellbore.

[0069] In summary, the present invention provides a wellbore gas intrusion monitoring device and method that utilizes pulsed Doppler technology. This device and method not only monitors the velocity of gas-liquid two-phase flow but also acquires real-time fluid information at a specific location, enabling real-time monitoring of gas content and flow patterns in downhole gas intrusion. Furthermore, requiring only a single ultrasonic transducer for both transmission and reception, the device is relatively low-cost and adaptable to most environments.

[0070] In order to further illustrate the present application, an embodiment is provided below in conjunction with FIG8 to simulate the gas intrusion monitoring device of the present application.

[0071] As shown in Figure 8, the system includes a drilling fluid pool, a water pool, a pump, an annular pipe, ultrasonic transducers (1, 2, 3), an ultrasonic detector, a digital instrument, a computer, an air compressor, and gas and liquid flow meters. The annular pipe is composed of the drill pipe and the wellbore wall. The drilling fluid in the drilling fluid pool is pumped into the annular pipe to simulate the working environment of the real drill pipe.

[0072] 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 crushing device. The gas flow meter can control the speed of gas injection from the air compressor to simulate gas intrusion in an underbalanced state and gas intrusion of varying degrees.

[0073] Three ultrasonic transducers can be installed at the bottom, middle, and top of the wellbore. A computer controls the ultrasonic detector to issue pulse signal control instructions. The ultrasonic transducer transmits a pulse wave with an incident angle of 45° into the annular pipe according to the pulse signal control instructions. The ultrasonic transducer then switches to receiving mode and receives the echo signal. The digitizer converts the echo signal into a digital signal and stores it in the computer.

[0074] The drilling process is complex, and the received echo signals contain various clutter signals. Therefore, orthogonal demodulation is first used to perform orthogonal demodulation on the received echo signals and extract the Doppler signal from them. After orthogonal demodulation, the useful Doppler signal is extracted and subjected to a short-time Fourier transform to obtain a Fourier time-frequency diagram. The Fourier spectrum in the Fourier time-frequency diagram is then subjected to a wavelet transform (e.g., an empirical wavelet transform) to obtain an energy distribution spectrum on the time-frequency plane. Finally, the Doppler amplitude of the echo signal is obtained from the energy distribution spectrum.

[0075] Combined with the changes in the time-frequency spectrum, various flow types can be identified by observing the changes in Doppler amplitude and energy distribution. Combined with the gas intrusion monitoring method described above in this application, whether gas intrusion occurs and the extent of gas intrusion can be measured and verified in real time.

[0076] After simulation tests, the gas intrusion monitoring method of this application was able to promptly and accurately identify different types of gas intrusion. This shows that the gas intrusion monitoring device and method of this application have good timeliness and accuracy for the oil and gas drilling field, and can greatly improve the monitoring accuracy of downhole gas flow information. Therefore, it has obvious technical advantages and is of great significance in preventing and controlling accidents such as blowouts.

[0077] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0078] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A gas intrusion monitoring device for a wellbore, characterized in that: The gas intrusion monitoring device comprises: An ultrasonic transducer is used to transmit pulsed ultrasonic waves to the annular pipe of the wellbore in a transmitting mode, wherein the pulsed ultrasonic waves are reflected by a mobile scatterer at a set position in the annular pipe and generate an echo signal; and receive the echo signal in a receiving mode; a data processing device, 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 invasion occurs in the wellbore according to the Doppler amplitude of the echo signal.

2. The wellbore gas intrusion monitoring device according to claim 1, characterized in that: Determining whether gas invasion occurs in the wellbore includes: Determining the fluid flow pattern of the annular pipe at the set position according to the Doppler amplitude of the echo signal; and Whether gas invasion occurs in the wellbore is determined according to the fluid flow pattern of the annular pipe at the set position.

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

4. The wellbore gas intrusion monitoring device according to claim 3, characterized in that: Determining whether gas invasion occurs in the wellbore includes: In the case where the ultrasonic transducer is one ultrasonic transducer, if the fluid flow pattern is a bubble flow, it is determined that no gas invasion occurs in the wellbore; if the fluid flow pattern is a plug flow or a stirring flow, it is determined that gas invasion occurs in the wellbore; or In the case where the ultrasonic transducer is a plurality of ultrasonic transducers, if the fluid flow types of the annular pipe at a plurality of set positions are all bubble flows, it is determined that gas intrusion has not occurred in the wellbore; if there is a plunger flow or a stirring flow in at least one set position of the annular pipe, it is determined that gas intrusion has occurred in the wellbore.

5. The wellbore gas intrusion monitoring device according to claim 4, characterized in that: In the case of gas invasion in the wellbore, the determination module is further used to determine the extent of gas invasion in the wellbore according to the fluid flow pattern of the annular pipe at the set position. Determining the extent of gas invasion in the wellbore includes: In the case where the ultrasonic transducer is one ultrasonic transducer, if the fluid flow pattern is a plug flow, it is determined that moderate gas invasion occurs in the wellbore, and if the fluid flow pattern is a stirring flow, it is determined that severe gas invasion occurs in the wellbore; or In the case where the ultrasonic transducer is a plurality of ultrasonic transducers, if there is bubble flow and plunger flow in the annulus pipe, it is determined that moderate gas invasion has occurred in the wellbore; if there is no bubble flow in the annulus pipe, it is determined that severe gas invasion has occurred in the wellbore.

6. The wellbore gas intrusion monitoring device according to claim 4 or 5, characterized in that: In the case that the ultrasonic transducer is a plurality of ultrasonic transducers, the plurality of ultrasonic transducers are distributed at the bottom, the middle and the top of the outside of the wellbore.

7. The wellbore gas intrusion monitoring device according to any one of claims 1 to 5, characterized in that: The ultrasonic transducer transmits pulse ultrasonic waves to the annular pipe at a set incident angle in a transmitting mode.

8. The wellbore gas intrusion monitoring device according to any one of claims 1 to 5, characterized in that: The gas intrusion monitoring device also includes a control device for issuing a pulse signal control instruction, and the ultrasonic transducer switches between the transmission mode and the reception mode at a set time interval according to the pulse signal control instruction.

9. The wellbore gas intrusion monitoring device according to any one of claims 1 to 5, characterized in that: The processing of the echo signal comprises: Extracting the Doppler signal from the echo signal using an orthogonal demodulation technique; Performing short-time Fourier transform on the Doppler signal to obtain a Fourier time-frequency diagram; Performing wavelet transform on the Fourier spectrum in the Fourier time-frequency diagram to obtain an energy distribution spectrum diagram on the time-frequency plane; and The Doppler amplitude of the echo signal is acquired from the energy distribution spectrum.

10. A method for monitoring gas intrusion in a wellbore, characterized in that: The gas intrusion monitoring method comprises: The ultrasound transducer performs the following operations: In the transmitting mode, a pulse ultrasonic wave is transmitted to the annular pipe of the wellbore, and the pulse ultrasonic wave is reflected by a mobile scatterer at a set position in the annular pipe and generates the echo signal; and Receive echo signals in receiving mode; Processing the echo signal to obtain the Doppler amplitude of the echo signal; and Whether gas invasion occurs in the wellbore is determined according to the Doppler amplitude of the echo signal.

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