Intelligent monitoring system and method for carbon isotope of shaft gas

Abstract

The invention is applicable to the technical field of marine oil and gas resource exploration, and provides an intelligent monitoring system and method for carbon isotopes of wellbore gas, the system comprises an explosion-proof shell, and further comprises a gas pretreatment module for removing impurities affecting CH4 and C2H6 gas spectral lines and adjusting temperature and pressure of measured gas; the optical cavity detection module comprises a laser, a collimator, a detector and an MPC, and is used for completing the energy level excitation of the infrared light to the gas to be detected, the injection of a detection light source into the MPC from the laser, the multiple reflection of the detection light in the MPC, the built-in multi-beam laser light source, and the absorption detection of the multi-component gas through a single optical cavity; and the data processing module is used for collecting, processing, displaying and outputting the measured data in real time. The system is high in detection precision, high in environmental adaptability, high in response speed and miniaturized in equipment, and has a wide market prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine oil and gas resource exploration, and in particular relates to a wellbore gas carbon isotope intelligent monitoring system and method. Background Art

[0002] In the field of marine oil and gas exploration, the carbon isotope abundance of CH4 and C2H5 gases is a key parameter for determining oil and gas quality, tracing their genesis, and studying marine oil and gas accumulation. However, the current detection environment on offshore oil and gas drilling and production platforms is extremely complex, with significant differences in temperature and pressure between wells, a wide range of detected gas concentrations (10 ppm to 200,000 ppm), and complex gas compositions (mixtures of alkanes, ammonia, acetylene, and other gases).

[0003] Existing carbon isotope detection equipment has numerous shortcomings: Schlumberger's Geoservices real-time methane carbon isotope analyzer, based on the CRDS+ infrared absorption principle, can only analyze methane isotopes and has been discontinued; the UK-based CSS Isologger multi-component isotope analyzer, which uses IRMS mass spectrometry, has an analysis cycle of up to 5 minutes, suffers from poor stability, and cannot meet the requirements for thin sandstone detection; Suzhou Guande's Grand-3 carbon isotope analyzer, which uses hollow waveguide quantum laser technology, is bulky and difficult to use in the field. These issues severely hinder the efficient exploration and development of offshore oil and gas resources, necessitating the development of a high-precision, miniaturized, and intelligent wellbore gas carbon isotope detection system that can adapt to complex environments. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a wellbore gas carbon isotope intelligent monitoring system and method, aiming to solve the problems raised in the above background technology.

[0005] The embodiment of the present invention is implemented as follows: a wellbore gas carbon isotope intelligent monitoring system includes an explosion-proof housing and further includes:

[0006] A gas pre-processing module, which is used to remove impurities that affect the CH4 and C2H6 gas spectra and adjust the temperature and pressure of the measured gas;

[0007] An optical cavity detection module, connected to the gas pre-processing module, includes a laser, a collimator, a detector, and an MPC. The module is used to excite the energy levels of the gas to be tested with infrared light. The detection light source is emitted by the laser into the MPC, where it is reflected multiple times to increase the length of the beam path. A built-in multi-beam laser light source detects the absorption of multiple gas components through a single optical cavity.

[0008] The data processing module is used to collect, process, display and output the measurement data in real time.

[0009] A further technical solution also includes a degasser, which is connected to the gas pretreatment module and is used to degas the fluid in the wellbore and transport the degassing gas to the gas pretreatment module.

[0010] According to a further technical solution, the gas pretreatment module includes an impurity removal device and a temperature and pressure control unit;

[0011] The impurity removal device is connected to the degasser and is used to remove impurities that affect the CH4 and C2H6 gas spectra;

[0012] The temperature and pressure control unit is connected to the impurity removal device, and the impurity removal device is connected to the optical cavity detection module through the temperature and pressure control unit, and is used to adjust the temperature and pressure of the measured gas after impurities are removed.

[0013] According to a further technical solution, the explosion-proof housing is made of 316L stainless steel.

[0014] A further technical solution also includes a data visualization terminal, which is connected to the data processing module and is used to visualize the data received and processed by the data processing module.

[0015] Another object of an embodiment of the present invention is to provide a method for intelligently monitoring carbon isotopes of wellbore gas, based on the above-mentioned intelligent monitoring system for carbon isotopes of wellbore gas, comprising the following steps:

[0016] Step 1: Degas the fluid in the wellbore through the degasser and transport the degassed gas to the gas pretreatment module;

[0017] Step 2: The gas is pre-processed by the gas pre-processing module to remove impurities that affect the CH4 and C2H6 gas spectra. The temperature and pressure of the measured gas are adjusted according to the feedback from the data processing module to stabilize it at the optimal conditions required for detection. The gas is then transported to the optical cavity detection module.

[0018] Step 3: The optical cavity detection module uses a multi-beam laser light source to absorb and detect gas and transmits the data to the data processing module;

[0019] Step 4: The data processing module processes the collected data and displays the data through the data visualization terminal.

[0020] The embodiments of the present invention provide a system and method for intelligently monitoring carbon isotopes in wellbore gas, which have the following beneficial effects:

[0021] (1) High detection accuracy: Through high-precision optical cavity control technology and environmental correction algorithm, the interference of factors such as temperature and pressure is effectively reduced, and the detection accuracy can reach 0.4‰~1‰;

[0022] (2) Strong environmental adaptability: The gas pretreatment module and explosion-proof housing design enable the equipment to operate stably in the complex environment of offshore oil and gas drilling platforms, and adapt to large changes in temperature and pressure, as well as harsh conditions such as humidity and salt spray;

[0023] (3) Fast response speed: Adopting the "one-chamber multi-energy" structure and advanced detection principle, the analysis cycle is short, which can realize real-time online detection of carbon isotopes in wellbore gas and meet the rapid detection needs of thin sand bodies.

[0024] (4) Equipment miniaturization: The integrated design significantly reduces the size of the equipment, making it easier to install and use on offshore drilling platforms, overcoming the shortcomings of the existing equipment being bulky.

[0025] (5) Wide range of applications: It can not only be used for carbon isotope detection of wellbore gas in offshore oil and gas drilling and production platforms, but can also be promoted and applied to other fields that require gas carbon isotope detection, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for intelligently monitoring carbon isotopes of wellbore gas provided by an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the structure of an intelligent monitoring system for carbon isotopes of wellbore gas provided by an embodiment of the present invention;

[0028] Figure 3 A schematic structural diagram of an optical cavity detection module in an intelligent monitoring system for carbon isotopes in wellbore gas provided by an embodiment of the present invention;

[0029] Figure 4 This is a diagram showing the principle of carbon isotope line separation;

[0030] Figure 5 Comparison of different separation methods for carbon isotope lines over a wide range of methane concentrations;

[0031] Figure 6 is the carbon isotope concentration-second harmonic peak fitting;

[0032] Figure 7 To test the performance of methane concentration detection;

[0033] Figure 8 Allen's ANOVA for methane concentrations.

[0034] In the accompanying drawings: explosion-proof housing 1; gas pretreatment module 2; impurity removal device 21; temperature and pressure control unit 22; optical cavity detection module 3; data processing module 4; data visualization terminal 5; degasser 6; wellbore 7. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0037] like Figure 2 and Figure 3 As shown, an intelligent monitoring system for carbon isotopes of wellbore gas provided by one embodiment of the present invention includes an explosion-proof housing 1 and further includes:

[0038] Gas pretreatment module 2, which is used to remove impurities such as ammonia and acetylene that affect the CH4 and C2H6 gas spectra, and to adjust the temperature and pressure of the measured gas to stabilize it at the optimal conditions required for detection;

[0039] The optical cavity detection module 3 is connected to the gas pre-processing module 2. The optical cavity detection module 3 includes a laser, a collimator, a detector and an MPC, and is used to complete the energy level excitation of the gas to be tested by infrared light. The detection light source is emitted into the MPC by the laser; the detection light is reflected multiple times in the MPC to increase the length of the beam path and improve the isotope abundance of the system. A high-precision optical cavity structure is used with a built-in multi-beam laser light source to realize the absorption detection of multi-component gases in a single optical cavity;

[0040] The data processing module 4 is used to collect, process, display and output the measurement data in real time.

[0041] In the embodiment of the present invention, the optical cavity uses TEC temperature control technology and an anti-disturbance algorithm (this technology is existing and will not be elaborated in detail here) to stabilize the optical cavity temperature within ±100mK of the target temperature.

[0042] During operation, gas from the wellbore 7 passes through the gas pretreatment module 2 to remove impurities and stabilize the temperature and pressure before entering the optical cavity detection module 3. A multi-beam laser interacts with the gas within the optical cavity, detecting light absorption to determine the concentrations of gases such as CH4 and C2H6, as well as their carbon isotope abundances. The signal output from the optical cavity detection module 3 is transmitted to the data processing module 4, which processes the signal using an environmental correction algorithm to compensate for environmental factors. Ultimately, accurate carbon isotope detection results are obtained and displayed and output in real time.

[0043] The parameter comparison between this equipment and similar foreign equipment is shown in Table 1 below;

[0044] Table 1 Parameter comparison with similar foreign equipment

[0045]

[0046] As can be seen from the above table, the main parameters of this device are significantly better than similar competing products.

[0047] like Figure 2 As shown, as a preferred embodiment of the present invention, it also includes a degasser 6, which is connected to the gas pretreatment module 2 and is used to degas the fluid in the wellbore 7 and transport the degassing gas to the gas pretreatment module 2.

[0048] like Figure 2 As shown, as a preferred embodiment of the present invention, the gas pre-processing module 2 includes an impurity removal device 21 and a temperature and pressure control unit 22;

[0049] The impurity removal device 21 is connected to the degasser 6 and is used to remove impurities such as ammonia and acetylene that affect the CH4 and C2H6 gas spectra;

[0050] The temperature and pressure control unit 22 is connected to the impurity removal device 21, and the impurity removal device 21 is connected to the optical cavity detection module 3 through the temperature and pressure control unit 22, and is used to adjust the temperature and pressure of the measured gas after impurity removal to stabilize it at the optimal conditions required for detection.

[0051] As a preferred embodiment of the present invention, the data processing module 4 integrates an environmental correction algorithm and data processing software. The environmental correction algorithm is based on a deep learning control model and automatically compensates for measurement deviations caused by factors such as temperature, pressure, and gas concentration; the data processing software realizes real-time acquisition, processing, display, and output of measurement data, and has the characteristics of a friendly interface and convenient operation. Figure 4As shown in the figure, by carrying out a large number of indoor measurement experiments, the accuracy difference rules of the measurement results under different measured gas concentration conditions are compared, and the deep learning control model is used to perform theoretical simulation optimization to determine the automatic compensation parameters of the measured gas concentration under the best measurement accuracy. The carbon isotope absorption spectrum is complex, and oil and gas contain a variety of hydrocarbon gases and non-hydrocarbon compounds. There is a risk that other impurity gases will affect the detection. The potential spectral line overlap problem is solved by the second harmonic spectral line separation method (this method is a conventional experimental method and can be achieved through a spectrometer or a second harmonic generator). Seven parameters such as the concentration proportional coefficient are selected as the dimensional variables of the particles, and the harmonic waveform is fitted to achieve the effect of spectral line separation and avoid the influence of complex spectral lines on detection performance. As shown Figure 5 As shown in the figure, a single saturated absorption line concentration detection method is used to improve the measurement range of the sensing system in the context of wide-range methane concentration measurement. By measuring the maximum and minimum values ​​in the second harmonic waveform, as well as the sampling position difference between the maximum and minimum values, and combining it with neural network modeling, a regression prediction of concentration under saturated absorption is achieved. This method not only maintains the low detection limit performance of the TDLAS-WMS system, but also effectively improves the system's upper detection limit, achieving wide-range concentration measurement.

[0052] As a preferred embodiment of the present invention, the explosion-proof housing 1 is constructed from 316L stainless steel and adheres to strict airtightness and explosion-proof design standards to ensure safe operation of the equipment on offshore drilling platforms. Gas dilution is achieved by utilizing gas dilution equipment using two or more mass flow controllers to control the gas flow in different gas paths, achieving varying dilution ratios. The gas pipelines within the housing are filtered and dried to ensure compatibility with harsh offshore conditions such as humidity and salt spray.

[0053] like Figure 2 As shown, as a preferred embodiment of the present invention, it also includes a data visualization terminal 5, which is connected to the data processing module 4 and is used to visualize the data received and processed by the data processing module 4.

[0054] like Figure 1 As shown, another embodiment of the present invention provides a method for intelligently monitoring carbon isotopes of wellbore gas, based on the above-mentioned intelligent monitoring system for carbon isotopes of wellbore gas, comprising the following steps:

[0055] Step 1: Degas the fluid in the wellbore 7 through the degasser 6 and deliver the degassed gas to the gas pretreatment module 2;

[0056] Step 2: The gas is pre-processed by the gas pre-processing module 2 to remove impurities such as ammonia and acetylene. The temperature and pressure of the gas to be measured are adjusted according to the feedback from the data processing module 4 to stabilize it at the optimal conditions required for detection. The gas is then transported to the optical cavity detection module 3.

[0057] Step 3: The optical cavity detection module 3 uses a multi-beam laser light source to absorb and detect gas, and transmits the data to the data processing module 4;

[0058] Step 4: The data processing module 4 processes the collected data and displays the data through the data visualization terminal 5.

[0059] As a preferred embodiment of the present invention, a performance test was conducted on a methane isotope abundance detection prototype, and gas samples of 500, 800, 1000, 2000, 3000, 5000, 10000, and 15000 ppmv were prepared to test the system. 12 The calibration results of CH4 concentration are as follows: Figure 6 As shown, the calibration curve has a high degree of fit.

[0060] The calibrated methane carbon isotope detection system was subjected to a long-term stability test. A methane standard gas with a concentration of 6100ppm was introduced for testing. The methane carbon isotope detection system had an average measurement result of 6115ppm and a standard deviation of 3ppm within a 10-minute sampling time. The measurement results were normally distributed. The instrument maintained good stability over a long period of time. Figure 7 shown.

[0061] Allan variance was used to evaluate the system stability and detection limit. The concentration detection data in the experiment were used to perform Allan variance analysis on the system. Allan variance shows the relationship between the system integration time and the system isotope abundance detection precision. When the integration time is 1s, the system CH4 detection limit is about 886.9ppm; when the integration time is 644s, the system CH4 detection limit is about 74.9ppm. Figure 8 shown.

[0062] During gas pretreatment, the gas is first removed through a degasser 6 and then introduced into the gas pretreatment module 2 through the gas inlet. Impurities such as ammonia and acetylene are removed through adsorption and filtration, followed by drying to prevent interference with the spectral lines of CH4 and C2H6 gases. The temperature and pressure of the gas are then regulated by the temperature and pressure control unit 22, maintaining the temperature at approximately 303K and the pressure near standard atmospheric pressure, providing stable conditions for subsequent testing.

[0063] During cavity detection, pretreated gas enters the high-precision optical cavity of cavity detection module 3. A multi-beam laser source emits laser light of a specific wavelength, which reflects multiple times within the cavity, interacting with gas molecules. Gas molecules such as CH4 and C2H6 absorb laser light of specific wavelengths. According to the Lambert-Beer law, the gas concentration and carbon isotope abundance can be determined by measuring the absorption intensity of the laser light. The cavity utilizes TEC temperature control technology, combined with an auto-disturbance rejection algorithm, to monitor and adjust the cavity temperature in real time, stabilizing it within ±100mK of the target temperature, ensuring detection accuracy and stability.

[0064] The electrical signal output by the optical cavity detection module 3 is transmitted to the data processing module 4. The data processing module 4 first performs pre-processing such as amplification and filtering on the signal, and then uses the environmental correction algorithm based on the deep learning control model to automatically compensate for the measurement deviation caused by environmental factors such as temperature, pressure, and gas concentration. Specifically, through a large number of indoor measurement experiments, a mapping relationship between environmental factors and measurement deviations is established, and this relationship is learned and fitted using a deep learning model, thereby achieving real-time correction of the actual measurement data. The corrected data is processed by data processing software, including data smoothing, noise reduction, feature extraction, etc., and finally the carbon isotope abundance values ​​of gases such as CH4 and C2H6 are obtained, and displayed in real time through the human-computer interaction interface, and output in a standard data format for subsequent analysis and application.

[0065] Comparison of oil and gas sample test results:

[0066] Indoor testing of gas samples from the logging platform was conducted to measure the methane concentration and isotopic abundance in the oil and gas samples. First, a standard sample gas with a 13,000 ppm methane concentration and its -30.2‰ isotope were tested. The results, shown in Table 2, show an average methane concentration of 12,810.56 ppm and an average isotope abundance of -31.82‰, with an error of 1.62‰ compared to the standard sample gas.

[0067] Table 2 Comparison of measurement results of standard concentration of methane and its isotopes

[0068]

[0069] Twenty samples were collected from a well in WC, and laboratory comparisons of CH4 concentration and carbon isotope abundance were conducted. The results are shown in Table 3. The maximum deviation in carbon isotope abundance was 0.64‰, and the maximum deviation in concentration was 21 ppm. Comparison of the measured results with those from mud logging instruments showed good consistency.

[0070] Table 3 Comparison of 20 groups of wellbore gas samples

[0071]

[0072]

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An intelligent monitoring system for carbon isotopes in wellbore gas, comprising an explosion-proof housing, characterized in that: Also includes: A gas pre-processing module, which is used to remove impurities that affect the CH4 and C2H6 gas spectra and to adjust the temperature and pressure of the measured gas; An optical cavity detection module, connected to the gas pre-processing module, includes a laser, a collimator, a detector, and an MPC. The module is used to excite the energy levels of the gas to be tested with infrared light. The detection light source is emitted by the laser into the MPC, where it is reflected multiple times to increase the length of the beam path. A built-in multi-beam laser light source detects the absorption of multiple gas components through a single optical cavity. The data processing module is used to collect, process, display and output the measurement data in real time.

2. The intelligent monitoring system for carbon isotopes of wellbore gas according to claim 1, characterized in that: It also includes a degasser, which is connected to the gas pre-processing module and is used to degas the fluid in the wellbore and transport the degassing gas to the gas pre-processing module.

3. The intelligent monitoring system for carbon isotopes of wellbore gas according to claim 2, characterized in that: The gas pretreatment module includes an impurity removal device and a temperature and pressure control unit; The impurity removal device is connected to the degasser and is used to remove impurities that affect the CH4 and C2H6 gas spectra; The temperature and pressure control unit is connected to the impurity removal device, and the impurity removal device is connected to the optical cavity detection module through the temperature and pressure control unit, and is used to adjust the temperature and pressure of the measured gas after impurities are removed.

4. The intelligent monitoring system for carbon isotopes of wellbore gas according to claim 1, characterized in that: The explosion-proof housing is made of 316L stainless steel.

5. The intelligent monitoring system for carbon isotopes of wellbore gas according to claim 1, characterized in that: It also includes a data visualization terminal, which is connected to the data processing module and is used to visualize the data received and processed by the data processing module.

6. A method for intelligently monitoring carbon isotopes of wellbore gas, based on the intelligent monitoring system for carbon isotopes of wellbore gas according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Degas the fluid in the wellbore through the degasser and transport the degassed gas to the gas pretreatment module; Step 2: The gas is pre-processed by the gas pre-processing module to remove impurities that affect the CH4 and C2H6 gas spectra. The temperature and pressure of the measured gas are adjusted according to the feedback from the data processing module to stabilize it at the optimal conditions required for detection. The gas is then transported to the optical cavity detection module. Step 3: The optical cavity detection module uses a multi-beam laser light source to absorb and detect gas and transmits the data to the data processing module; Step 4: The data processing module processes the collected data and displays the data through the data visualization terminal.

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