Gas cut monitoring device and method for shaft

Abstract

The embodiment of the invention provides a gas cut monitoring device and method for a shaft, and belongs to the field of oil and gas drilling. The gas cut monitoring device comprises an ultrasonic transducer used for transmitting pulse ultrasonic waves to an annulus pipeline of a shaft in a transmitting mode, and the pulse ultrasonic waves are reflected when encountering a moving scatterer at a set position in the annulus pipeline and generate echo signals; and receiving an echo signal in a receiving mode; the data processing device is used for processing the echo signal to obtain Doppler amplitude of the echo signal; and the judgment module is used for judging whether gas cut occurs in the shaft or not according to the Doppler amplitude of the echo signal. Compared with the prior art, the gas cut monitoring device provided by the invention has good axial resolution, and can measure fluid at a specified position so as to extract fluid information. And meanwhile, the method has good timeliness and accuracy, monitoring and early warning can be carried out in time when gas cut occurs, and the well control time is prolonged.

Description

Technical Field

[0001] The invention 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

[0002] At present, as the geological conditions of oil and gas well development become more and more complex, it is easy to encounter abnormally high-pressure formations during drilling, gas invasion and various drilling safety accidents such as blowouts occur, which greatly threaten the safety of workers' lives and environmental protection. Therefore, the prevention and control of accidents such as blowouts play an increasingly important role in the drilling process.

[0003] If gas invasion occurs during drilling, it is difficult to detect it in the initial stage by monitoring methods such as fluid increment or flow differential overflow in the drilling fluid pool. At the same time, as the depth of the wellhead increases, it becomes more difficult to detect gas invasion in advance, which significantly reduces the time for well control. The method of monitoring while drilling is easily affected by downhole conditions, prone to distortion, and poorly adaptable to high temperature and high pressure environments.

[0004] 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 position; second, the ultrasonic signal first increases and then decreases with the increase of gas content, resulting in the inability to directly use ultrasonic characteristic parameters to judge the gas intrusion status.

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

[0006] The purpose of the embodiments of the present invention is to provide a gas invasion monitoring device and method for a wellbore, so as to obtain fluid information at a specified position and directly determine the gas invasion state by using ultrasonic characteristics.

[0007] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides a gas intrusion monitoring device for a wellbore, and the gas intrusion monitoring device includes: an ultrasonic transducer, which is used to transmit pulse ultrasonic waves to the annular pipe of the wellbore in a transmitting mode, and the pulse 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, which is used to process the echo signal to obtain the Doppler amplitude of the echo signal; and a judgment module, which is used to judge whether gas intrusion occurs in the wellbore according to the Doppler amplitude of the echo signal.

[0008] Optionally, determining whether gas invasion occurs in the wellbore includes: determining a fluid flow pattern of the annular pipe at the set position based on the Doppler amplitude of the echo signal; and determining whether gas invasion occurs in the wellbore based on the fluid flow pattern of the annular pipe at the set position.

[0009] 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.

[0010] Optionally, the determining whether gas intrusion occurs in the wellbore includes: when the ultrasonic transducer is one ultrasonic transducer, if the fluid flow type is bubble flow, determining that gas intrusion does not occur in the wellbore, and if the fluid flow type is plug flow or stirring flow, determining that gas intrusion occurs 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 does not occur in the wellbore, and if there is plug flow or stirring flow in at least one set position of the annular pipe, determining that gas intrusion occurs in the wellbore.

[0011] 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 annulus pipe at the set position, and 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 are 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.

[0012] 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.

[0013] Optionally, the ultrasonic transducer transmits pulsed ultrasonic waves to the annular pipe at a set incident angle in a transmission mode.

[0014] 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.

[0015] Optionally, the processing of the echo signal includes: extracting a Doppler signal from the echo signal using an orthogonal demodulation technique; 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.

[0016] On the other hand, the present invention provides a method for monitoring gas intrusion in a wellbore, the method comprising: performing the following operations by means of an ultrasonic transducer: transmitting pulsed ultrasonic waves to an annular pipe of the wellbore in a transmitting mode, the pulsed ultrasonic waves being reflected by a mobile scatterer at a set position in the annular pipe and generating 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.

[0017] Compared with the prior art, the present invention can have good axial resolution through the above technical solution, and can obtain information at a specified position by setting an ultrasonic transducer and setting the position of the ultrasonic transducer, and can measure the fluid at the specified position and extract fluid information. At the same time, the solution of the present invention also has good timeliness and accuracy, and can monitor and warn in time when gas invasion occurs and increase the well control time.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

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

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

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

[0023] Figure 4a-4b is a schematic diagram of a fluid flow pattern of a stirring flow according to an embodiment of the present invention;

[0024] Figure 5a-5cis a schematic diagram of fluid flow patterns at different positions in an annular pipe according to an embodiment of the present invention;

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

[0026] Figure 7 is a flow chart of a method for monitoring gas intrusion in a wellbore according to an embodiment of the present invention;

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

[0028] Description of Reference Numerals

[0029] 100, annular pipe; 200, ultrasonic transducer; 300, data processing device; 400, determination module;

[0030] 210. Ultrasonic detector; 310. Digital instrument; 320. Computer. DETAILED DESCRIPTION

[0031] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0032] The present invention provides a gas intrusion monitoring device for a wellbore, such as Figure 1 The gas invasion monitoring device may include: an ultrasonic transducer 200, which is used to emit pulse ultrasonic waves to the annular pipe 100 of the wellbore in the transmitting mode, and the pulse ultrasonic waves are reflected by the mobile scatterer at the set position in the annular pipe 100 and generate echo signals; and receive the echo signals in the receiving mode; a data processing device 300, which is used to process the echo signals to obtain the Doppler amplitude of the echo signals; and a determination module 400, which is used to determine whether gas invasion occurs in the wellbore according to the Doppler amplitude of the echo signals.

[0033] in, Figure 1 The dotted lines in indicate that the ultrasonic transducer 200 transmits and receives pulse ultrasonic waves to the annular pipe 100 , and the solid lines indicate 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 .

[0034] After the ultrasonic wave enters the annular pipe 100, due to the different acoustic intensity reflectivity between the gas and liquid phases, the received echo signals are also different, so the difference of the moving scatterer can be distinguished according to the signal difference of the echo signal. Compared with the wave Doppler technology used in the prior art, the present invention adopts ultrasonic pulse Doppler, and can transmit and receive ultrasonic waves at a certain time interval through the self-transmitting and self-receiving ultrasonic transducer 200, that is, it is converted to the receiving mode after transmitting the ultrasonic wave, and converted 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, the echo signal of the required measurement point can be selectively received (and the received echo signals do not overlap), so it can have axial resolution. At the same time, the present invention can realize the acquisition of information at a specified position by setting the position of the transducer, can measure the fluid at the specified position and then extract fluid information, and obtain information on the gas flow at the specified position. In addition, the present invention also has good timeliness and accuracy, and can monitor and warn in time when gas invasion occurs and increase the well control time.

[0035] In one embodiment, the ultrasonic transducer 200 can be installed on the outside of the annular pipe 100 to avoid any impact on the drilling fluid in the annular pipe 100. In addition, the ultrasonic transducer 200 can transmit pulse ultrasonic waves to the annular pipe 100 at a set incident angle in the transmission mode. The role of setting the incident angle is to reduce the impact of the wellbore wall on the ultrasonic wave. These impacts can be reduced by adjusting the incident angle according to the different materials of the wellbore wall. Preferably, the incident angle is set to 30-60°.

[0036] In one embodiment, the ultrasonic transducer 200 can be set to one or more. In the case of setting one ultrasonic transducer, in order to better achieve the detection effect, the ultrasonic transducer 200 should be placed in the middle of the outside of the wellbore, so that the accuracy and timeliness of monitoring can be taken into account at the same time. Preferably, in the case of setting multiple ultrasonic transducers, it should be ensured that at least one ultrasonic transducer is located in the middle of the outside of the wellbore. For example, three ultrasonic transducers can be provided, which are respectively distributed at the top, middle and bottom of the outside of the wellbore. The specific setting position can be adaptively adjusted according to the needs of different application scenarios. For example, if the total length of the wellbore is L, the upper ultrasonic transducer can be placed at a distance L from the top of the wellbore. 1 Set to 1 / 4-1 / 3L, the distance between the middle ultrasonic transducer and the top of the wellbore can be L 2 Set to 1 / 3-2 / 3L, the distance L between the bottom ultrasonic transducer and the top of the wellbore can be 3 It is set to 2 / 3-3 / 4 L. More preferably, the distance between two adjacent ultrasonic transducers is not less than 1 / 6-1 / 4 L.

[0037] In one embodiment, the determination module 400 may include: a fluid flow type determination module, used to determine the fluid flow type of the annular pipe 100 at a set position according to the Doppler amplitude of the echo signal; and a gas invasion determination module, used to determine whether gas invasion occurs in the wellbore according to the fluid flow type of the annular pipe 100 at a set position.

[0038] 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.

[0039] In principle, when gas intrusion occurs, the gas intrudes into the annular pipe and presents a gas-liquid two-phase flow state. Therefore, the amount of gas intrusion can be judged according to the fluid flow pattern. For example, the following may occur: Figure 2a , 3a , 4a, namely, bubble flow, plug flow and stirring flow. Figure 2a , 3a 4a is a real picture taken with a high-speed camera. Figure 2b , 3b 4b is the time-frequency spectrum of the processed Doppler amplitude.

[0040] Specifically, Figure 2a The presence of small bubbles with a diameter of about 5 mm in the pipeline is called bubble flow. In this case, it is generally considered a normal phenomenon of gas in the liquid and is not considered to be gas intrusion. Figure 2b The magnitude of the Doppler amplitude, which indicates the measured bubble position, is at a low level.

[0041] Figure 3a Many small bubbles aggregate to form large bubbles with a diameter close to the inner diameter of the pipe, followed by many small bubbles at the tail, which is called plunger flow. At this time, the bubble velocity increases significantly, showing a certain degree of gas invasion. Figure 3b This indicates that the measured Doppler amplitude also increases significantly.

[0042] Figure 4a The gas flow in the pipeline becomes more chaotic. The large-sized bubbles appear irregular in shape compared to the large-sized bubbles in the plunger flow. The small-sized bubbles surround the large-sized bubbles and are in large numbers. This is called stirring flow. At this time, it can be determined that gas intrusion has obviously occurred. Figure 4b The magnitude of 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 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 make adaptive settings based on actual application conditions, and the present invention does not make specific limitations on this.

[0044] In one embodiment, when the ultrasonic transducer 200 is one ultrasonic transducer, the ultrasonic transducer is preferably disposed in the middle of the outer side of the wellbore. 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 plunger flow or a stirring flow, it is determined that gas invasion occurs in the wellbore.

[0045] In one embodiment, when the ultrasonic transducer 200 is a plurality of ultrasonic transducers, for example, three ultrasonic transducers are provided. Figure 5a-5c As shown. At this time, the plurality of ultrasonic transducers are preferably arranged at the bottom, middle and upper part of the outside of the wellbore. If the fluid flow patterns of the annular pipe 100 at the plurality of set positions are all bubble flow ( Figure 5a ), it is determined that no gas invasion has occurred in the wellbore. If there is a plug flow or a stirring flow ( Figure 5b and Figure 5c ), it is determined that gas invasion has occurred in the wellbore.

[0046] In one embodiment, when gas invasion occurs in the wellbore, the determination module 400 is further used to determine the extent of gas invasion in the wellbore according to the fluid flow pattern of the annular pipe 100 at a set position.

[0047] In one embodiment, when the ultrasonic transducer 200 is one ultrasonic transducer, the ultrasonic transducer is preferably disposed in the middle of the outer side of the wellbore. If the fluid flow pattern is a plug flow, it is determined that moderate gas invasion occurs in the wellbore. If the fluid flow pattern is a stirring flow, it is determined that severe gas invasion occurs in the wellbore.

[0048] In one embodiment, when the ultrasonic transducer 200 is a plurality of ultrasonic transducers, for example, three ultrasonic transducers are provided. Figure 5b and Figure 5c As shown. At this time, the plurality of ultrasonic transducers are preferably arranged at the bottom, middle and upper parts of the outside of the wellbore. If there is a bubble flow and a plunger flow ( Figure 5b ), it is determined that moderate gas invasion occurs in the wellbore; if there is no bubble flow in the annular pipe 100 ( Figure 5c ), it is determined that severe gas invasion has occurred in the wellbore.

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

[0050] 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.

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

[0052] Due to the complex working conditions of the drilling process, the received echo signal may contain various clutters, so it is necessary to perform orthogonal demodulation on the received echo signal, extract the useful Doppler signal after orthogonal demodulation, perform short-time Fourier transform and obtain the energy distribution spectrum diagram based on empirical wavelet transform. For example, the Fourier spectrum of the Doppler echo signal can be adaptively segmented by the EWT algorithm, and the single component containing the Doppler frequency shift can be extracted. Then, the single component component can be Hilbert transformed to obtain the energy distribution spectrum diagram of the signal on the time-frequency plane. Various flow types can be identified by observing the changes in the Doppler amplitude and the changes in the energy distribution. In addition, through the Doppler frequency shift signal, the pulse Doppler technology can detect the flow direction of the fluid at each position in the annular pipe 100, and then determine the velocity vector of the fluid at that position. The velocity vector of the fluid can be used to assist in verifying whether gas invasion occurs in the wellbore.

[0053] The present invention also provides a method for monitoring gas intrusion in a wellbore, such as Figure 7 The gas invasion monitoring method may include: S100, performing the following operations by means of an ultrasonic transducer: transmitting pulse ultrasonic waves to the annular pipe in a transmitting mode, wherein the pulse 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; S200, processing the echo signal to obtain the Doppler amplitude of the echo signal; and S300, determining whether gas invasion occurs in the wellbore according to the Doppler amplitude of the echo signal.

[0054] 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 of the moving scatterer can be distinguished according to the signal difference of the echo signal. Compared with the prior art, the present invention adopts ultrasonic pulse Doppler, and can transmit and receive ultrasonic waves at a certain time interval through a self-transmitting and self-receiving ultrasonic transducer, that is, it is converted to a receiving mode after transmitting the ultrasonic wave, and converted 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 measuring points can be selectively received (and the received echo signals do not overlap), so the present invention can have axial resolution. At the same time, by setting the position of the transducer, the acquisition of information at the specified position can be realized, and the fluid at the specified position can be measured and then the fluid information can be extracted, and the information of the gas flow at the specified position can be obtained. In addition, the present invention also has good timeliness and accuracy, and can monitor and warn in time when gas invasion occurs and increase the well control time.

[0055] In one embodiment, the ultrasonic transducer can be installed outside the annular pipe to avoid any impact on the drilling fluid in the annular pipe. In addition, the ultrasonic transducer can transmit pulse ultrasonic waves to the annular pipe at a set incident angle in the transmission mode. The role of setting the incident angle is to reduce the impact of the wellbore wall on the ultrasonic wave. These impacts can be reduced by adjusting the incident angle according to the different materials of the wellbore wall. Preferably, the incident angle is set to 30-60°.

[0056] In one embodiment, the ultrasonic transducer in step S100 can be set to one or more. In the case of setting one ultrasonic transducer, in order to achieve a better detection effect, the ultrasonic transducer should be placed in the middle of the outer side of the wellbore, so that the accuracy and timeliness of monitoring can be taken into account at the same time. In the case of setting multiple ultrasonic transducers, it should be ensured that at least one ultrasonic transducer is located in the middle of the outer side of the wellbore. Preferably, three ultrasonic transducers can be provided, respectively located at the upper part, the middle part and the bottom of the outer side of the wellbore.

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

[0058] In one embodiment, a digitizer 310 and a computer 320 may be 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.

[0059] 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.

[0060] Due to the complex working conditions of the drilling process, the received echo signal may contain various clutters. Therefore, it is necessary to perform orthogonal demodulation on the received echo signal, extract the useful Doppler signal after orthogonal demodulation, and perform short-time Fourier transform to obtain the time-frequency diagram. For example, the Fourier spectrum of the Doppler echo signal can be adaptively segmented by the EWT algorithm, and the single component containing the Doppler frequency shift can be extracted. Then, the single component component can be Hilbert transformed to obtain the energy distribution spectrum of the signal on the time-frequency plane. Various flow types can be identified by observing the changes in the Doppler amplitude and the changes in the energy distribution. In addition, through the Doppler frequency shift signal, the pulse Doppler technology can detect the flow direction of the fluid at each position in the annular pipe, and then determine the velocity vector of the fluid at that position. The velocity vector of the fluid can be used to assist in verifying whether gas invasion has occurred in the wellbore.

[0061] In one embodiment, the determining whether gas invasion occurs in the wellbore S300 may include: S310, determining the fluid flow pattern of the annular pipe at a set position according to the Doppler amplitude of the echo signal; and S320, determining whether gas invasion occurs in the wellbore according to the fluid flow pattern of the annular pipe at the set position.

[0062] 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 plunger flow; and S313, if the Doppler amplitude is greater than the second threshold, determining that the fluid flow type is a stirring flow.

[0063] In one embodiment, the determination of whether gas intrusion occurs 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, it is determined that gas intrusion does not occur in the wellbore; if the fluid flow pattern is a plunger flow or a stirring flow, it is determined that gas intrusion occurs in the wellbore.

[0064] In one embodiment, the determining whether gas invasion occurs 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, such as Figure 5a-5c At this time, it is preferred to arrange the plurality of ultrasonic transducers at the bottom, middle and upper part of the outside of the wellbore. If the fluid flow patterns of the annular pipe at the plurality of set positions are all bubble flow ( Figure 5a ), it is determined that there is no gas invasion in the wellbore; if there is a plug flow or stirring flow in at least one set position in the annular pipe ( Figure 5b and Figure 5c ), it is determined that gas invasion has occurred in the wellbore.

[0065] In one embodiment, in the event of gas invasion 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.

[0066] In one embodiment, the determination of the degree of gas invasion in the wellbore S400 may include: S401, when the ultrasonic transducer is a single ultrasonic transducer (preferably the ultrasonic transducer is disposed in the middle of the outside of the wellbore), if the fluid flow pattern is a plug 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.

[0067] In one embodiment, the determining the extent of gas invasion in the wellbore S400 may further include: S402, in the case where the ultrasonic transducer is a plurality of ultrasonic transducers (for example, three ultrasonic transducers are provided, such as Figure 5b and Figure 5c At this time, it is preferred to arrange the plurality of ultrasonic transducers at the bottom, middle and upper parts of the outside of the wellbore. If there is bubble flow and plunger flow ( Figure 5b ), it is determined that moderate gas invasion occurs in the wellbore; if there is no bubble flow in the annulus pipe ( Figure 5c ), it is determined that severe gas invasion has occurred in the wellbore.

[0068] In summary, the gas invasion monitoring device and method provided by the present invention adopts pulse Doppler technology, which can not only monitor the velocity of gas-liquid two-phase flow, but also obtain the fluid information of the specified position in real time, and realize the real-time monitoring of the gas content and flow type of gas invasion in the well. And only a single ultrasonic transducer needs to be installed to realize the functions of transmission and reception, which is relatively low in cost and can adapt to most environments.

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

[0070] like Figure 8As shown in the figure, it includes: a drilling fluid pool, a water pool, a pump, an annulus pipe, an ultrasonic transducer (1, 2, 3), an ultrasonic detector, a digital instrument, a computer, an air compressor, and a gas and liquid flow meter. The annulus pipe is composed of a drill pipe and a wellbore wall. The drilling fluid in the drilling fluid pool is injected into the annulus pipe through a pump to simulate the working environment of a real drill pipe.

[0071] In addition, the gas intrusion simulation device is composed of an air compressor, a water pool, a gas flow meter, a liquid flow meter and a bubble crushing device. The gas flow meter can control the speed of gas injection by the air compressor to simulate gas intrusion and gas intrusion of different degrees in an underbalanced state.

[0072] The ultrasonic transducer can be set to three, which are installed at the bottom, middle and top of the outside of the wellbore. The computer can control the ultrasonic detector to send out a pulse signal control instruction. The ultrasonic transducer emits a pulse wave with an incident angle of 45° into the annular pipe according to the pulse signal control instruction. Then the ultrasonic transducer is converted into a receiving mode to receive the echo signal. The digitizer converts the echo signal into a digital signal and stores it in the computer.

[0073] The drilling process is complicated, and the received echo signal contains various clutters. Therefore, the orthogonal demodulation technology is first used to orthogonally demodulate the received echo signal and extract the Doppler signal from the echo signal. After orthogonal demodulation, the useful Doppler signal is extracted and short-time Fourier transform is performed to obtain the Fourier time-frequency diagram. Then the Fourier spectrum in the Fourier time-frequency diagram is subjected to wavelet transform (such as empirical wavelet transform) to obtain the energy distribution spectrum diagram on the time-frequency plane. Finally, the Doppler amplitude of the echo signal is obtained from the energy distribution spectrum diagram.

[0074] 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 of the present invention as described above, it is possible to measure and verify the occurrence of gas intrusion and the degree of gas intrusion in real time.

[0075] After simulation tests, different types of gas intrusion can be identified timely and accurately using the gas intrusion monitoring method of the present invention. It can be seen that the gas intrusion monitoring device and method of the present invention have good timeliness and accuracy for the oil and gas drilling field, and can well improve the monitoring accuracy of underground gas flow information. Therefore, it has obvious technical advantages and is of great significance for the prevention and control of accidents such as blowouts.

[0076] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0077] The above are only 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 modification, equivalent substitution and improvement made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A gas intrusion monitoring device for a wellbore, It is 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, It is 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, It is 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, It is 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, It is 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, It is 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, It is 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, It is 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, It is 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, It is 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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