A TNIS Plus control method for thermal neutron imaging saturation logging

Abstract

This invention belongs to the field of well logging control technology, specifically relating to a TNIS Plus control method for thermal neutron imaging saturation logging. Applied to a well logging system including a remote transmission sub, an acquisition sub, and a high-pressure control sub, the method initiates initialization and magnetic positioning calibration by issuing a start command, performs magnetic temperature normalization, and controls the neutron generator to emit thermal neutron beams according to a dynamic pulse timing sequence. The high-pressure control sub provides the anode voltage. Based on timestamps, a multi-detector timing acquisition window is triggered, and sliding integration, energy spectrum layering filtering, and abnormal pulse shielding are performed on the detection data to form structured measurement subframes, which are then encapsulated and uploaded. When a high air recovery rate is detected, compensation sampling logic is automatically triggered to extend the sampling window and adjust the voltage threshold, improving the signal-to-noise ratio and spectral quality. This method achieves high-precision acquisition and stable transmission of well logging data, providing a reliable data foundation for formation water saturation inversion.

Description

Technical Field

[0001] This invention belongs to the field of well logging control technology, specifically relating to a thermal neutron imaging saturation logging TNIS Plus control method. Background Technology

[0002] In today's oil and gas field exploration and development, well logging technology has become one of the key means to identify reservoir properties, optimize development plans, and improve recovery rates. Especially under complex reservoir conditions, quantitatively assessing the saturation distribution of oil, water, and gas phases in the formation is of great significance for improving development efficiency, determining the location of remaining oil, and formulating precise injection and production strategies. Thermal neutron imaging logging, as an advanced technology that relies on the interaction between neutrons and formation materials to obtain fluid distribution information, is gaining increasing importance in formation fluid identification due to its non-invasiveness and response sensitivity. With the continuous upgrading of logging technology, the miniaturization, multi-functionality, and integration of logging instruments have become the mainstream trends in technological development.

[0003] Currently, common technical approaches in thermal neutron logging mainly include neutron-gamma spectrum analysis based on a single neutron detector and neutron time spectrum comparison analysis using dual probes. These traditional systems often focus only on estimating the saturation of a single phase (such as water or oil), lacking the comprehensive analytical capability for scenarios where multiple fluids coexist. Especially in operating environments with high temperature and pressure, complex geological structures, or limited wellbore conditions, their measurement accuracy, imaging resolution, and functional expandability are all limited. For example, while the traditional neutron lifetime method can estimate water saturation, it is difficult to effectively distinguish the response differences between oil and gas layers and water-bearing layers; the carbon-oxygen ratio method is suitable for oil-bearing identification, but its identification accuracy decreases in the context of gas interference. In addition, existing logging equipment often has dispersed modular functions, complex communication interfaces, and lacks a unified control logic and data coordination mechanism, resulting in low system integration, cumbersome debugging, high failure rate, and difficulty in adapting to the field application needs of multiple well sections and wide operating conditions.

[0004] Based on the above technical background, there is an urgent need to develop a comprehensive logging device that integrates multi-probe time spectrum and energy spectrum collaborative analysis capabilities, has a modular structure and intelligent remote transmission control, so as to achieve accurate identification and integrated measurement of formation water, oil and gas saturation. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to propose a thermal neutron imaging saturation logging TNIS Plus control method, applied to a formation element saturation measuring instrument, comprising a remote transmission sub, a data acquisition sub, and a high-pressure control sub connected in sequence, and including the following steps:

[0006] S1. The ground system issues a start command, the remote transmission sub receives the command and initializes the communication channels with each logging submodule, while recording the initialization timestamp and assigning task sequence numbers;

[0007] S2. The remote transmission short section scheduling magnetic positioning component performs drilling casing coupling positioning operation, obtains well depth reference position parameters, and performs magnetic temperature standardization calibration of the logging operation parameters in combination with temperature and pressure data.

[0008] S3. After the position parameters are confirmed, the control neutron generator emits a thermal neutron beam according to the preset neutron emission pulse timing. The pulse timing curve is determined by the control algorithm based on the well depth segmentation characteristics and the formation inversion model. The control high-pressure unit provides the anode pulse voltage according to the set target pressure waveform.

[0009] S4. The high-voltage control subsection triggers the timing acquisition windows of the first detector, the second detector, and the third detector respectively according to the neutron emission event timestamp. The length of the acquisition window is related to the neutron lifetime, the layer absorption characteristics, and the ambient temperature.

[0010] S5, the high-voltage control subsection preprocesses the data collected by the detector, including time spectrum window sliding integration, energy spectrum layer filtering and abnormal pulse shielding, to generate structured measurement subframes;

[0011] S6. Each measurement subframe is bound to the detector type, layer label, and transmission sequence number, encapsulated into a logging data frame, and uploaded to the ground system after being cached layer by layer through the remote transmission circuit.

[0012] S7. During the acquisition process, if a detector exceeds the preset empty sampling rate threshold, the compensation sampling logic will be automatically triggered to extend the sampling window of the detector and adjust the voltage threshold in order to improve the signal-to-noise ratio and ensure the spectral quality.

[0013] S8, the remote transmission short section, monitors the connection and disconnection status and abnormal coding of the three detector data links in real time. When multiple consecutive frames are lost, it activates the redundant channel to send short format alarm frames and records the alarm log and timestamp, which is then uploaded to the ground system.

[0014] As a preferred technical solution, in S3, the neutron emission pulse timing includes the following parameters:

[0015] Pulse width, pulse interval, sequence length, and energy distribution coefficient;

[0016] Among them, the pulse interval is dynamically adjusted according to the statistical value of neutron capture cross section in different well sections, the pulse width is adjusted according to the target voltage and the preheating state of the hot wire, and the sequence length is adjusted according to the predetermined sampling confidence level of the target layer.

[0017] As a preferred technical solution, the acquisition window in S4 is defined in segments according to the detector type:

[0018] The window corresponding to the first detector is within 1–100 μs after the neutron bombardment;

[0019] The window corresponding to the second detector is divided into a non-explosive window of 1–50 μs and a capture window of 50–300 μs;

[0020] The window corresponding to the third detector is a continuous range of 300–800 μs.

[0021] As a preferred technical solution, the preprocessing in S5 includes the following steps:

[0022] S51. Perform a sliding integration operation on the neutron time spectrum data. Specifically, slide the time axis at a preset time window on the time axis starting from the neutron emission reference time. Integrate the counted events in each sliding window to generate a discretized time spectrum integration sequence. The time window is determined according to the detector type and the neutron lifetime constant. The integration sequence is used for subsequent water saturation inversion.

[0023] S52. Perform hierarchical filtering on the gamma spectrum data, specifically: establish a predefined energy spectrum hierarchy structure according to different energy segments, divide the original energy spectrum into three energy segments: non-bullet region, capture region and excitation region, apply bandpass filtering and statistical threshold elimination algorithms to each energy segment, retain the main peak of the energy spectrum and suppress tail noise components, and use the filtered multi-segment spectrum shape for oil-bearing feature identification and carbon-oxygen ratio calculation.

[0024] S53. Perform masking processing on abnormal pulses in the detector output signal, specifically including: checking whether the pulse width and amplitude meet the expected range of statistical distribution, using upper and lower limit rejection rules to mark abnormal pulses as invalid values ​​and remove them from the original dataset; at the same time, construct an abnormal event index table to mark the frequency of abnormalities and the acquisition quality level within the time period;

[0025] S54. Combine the processed time spectrum integral sequence with metadata such as energy spectrum multi-segment feature data, detector identifier, timestamp, and sampling sequence number, and encapsulate it into a structured measurement subframe.

[0026] The measurement subframe is a data structure with a fixed format, containing a check bit and a sequence control field, which is suitable for data synchronization processing required for remote transmission link uploading and ground inversion calculation.

[0027] S55. After each measurement cycle ends, all measurement subframes generated by the detectors in this cycle are cached and integrated, and then the data frame encapsulation and uploading process begins.

[0028] As a preferred technical solution, in S55, the data frame encapsulation and upload process adopts a priority scheduling mechanism, including:

[0029] The logging frames are divided into high-priority main frames and low-priority monitoring frames.

[0030] High-priority main frames include detector number, time stamp, spectral summary information, and well section identifier;

[0031] Low-priority monitoring frames include device temperature, voltage, current, and detector health status;

[0032] The two types of frames are asynchronously uploaded at different bit rates using a time-division multiplexing communication strategy.

[0033] As a preferred technical solution, step S7 specifically includes:

[0034] S71. The high-voltage control sub continuously monitors the effective pulse count value of each detector within a unit sampling period and calculates the ratio of this value to the standard pulse reference value. If the ratio is lower than the set effective rate lower limit threshold, it is determined that the detector is currently in a high air sampling rate state.

[0035] S72. After detecting that the high-altitude sampling state is detected, the high-voltage control sub-section sends a sampling window adjustment command to the detector. The command includes a parameter value of the extended duration. The sampling window is extended by the extended duration based on the original sampling period. The value of the extended duration is determined based on the average response delay of the current layer of the detector.

[0036] S73. The high-voltage control sub-section sends a gain adjustment command to the front-end analog-to-digital conversion channel to adjust the signal voltage threshold of the detector sampling circuit from the original threshold voltage to the enhanced threshold voltage in the enhanced state. The enhanced threshold voltage is smaller than the original threshold voltage. The enhanced threshold voltage is determined based on the joint fitting result of the noise ground wire distribution and the signal peak frequency density in the previous cycle.

[0037] S74. During the compensation sampling period, the high-voltage control sub-section enables multi-channel redundant sampling, records the main channel data and the compensation channel data respectively, and adds an identification field to distinguish the original sampling data from the compensation data.

[0038] S75. After completing the compensation sampling, the two types of data are merged into the time axis alignment process, and the subsequent preprocessing module performs unified spectral shape construction and spectral segment selection operations.

[0039] S76. If the detector's empty sampling rate remains higher than the lower limit of efficiency for three consecutive cycles, the high-voltage control subsection enters a delayed backoff state, suspends the main channel sampling of the detector for 5 seconds, and retains only the low-speed sampling path of the compensation channel as a backup data sampling strategy to reduce system load and protect the stability of spectral quality.

[0040] As a preferred technical solution, the magnetic temperature normalization calibration performed by the teleportation sub-junction in S2 adopts a synchronous sampling mechanism, specifically including:

[0041] The magnetic positioning signal is generated within a 50ms window after the metal disturbance in the drilling string subsides;

[0042] Temperature and pressure data were acquired at 200ms intervals, and a linear fitting function was constructed within 3 seconds.

[0043] If the fitting residual exceeds the set error threshold, the measurement is discarded as an invalid value and resampled.

[0044] The obtained valid values ​​are encapsulated in a JSON structure and uploaded as additional header information for the logging frame.

[0045] As a preferred technical solution, the anode voltage control process includes:

[0046] During the initialization phase, the high-voltage power supply module outputs the initial target voltage and the hot wire preheating current.

[0047] 15ms before launch, the high-voltage control circuit raises the target pressure to the target pressure and completes neutron emission within the maintenance time.

[0048] After neutron emission ends, the anode voltage is restored to a safe anode voltage using a preset decay curve to prevent the residual hot wire from burning out.

[0049] All voltage and current status parameters are recorded by the control circuit and embedded as additional parameters in the upload frame.

[0050] As a preferred technical solution, the remote transmission short-section monitoring mechanism includes the following process:

[0051] Maintain a timestamp-based frame reception record buffer in real time;

[0052] If no acquisition subframe is received for more than 5 consecutive seconds, it is considered a link anomaly.

[0053] Initiate a soft reconnection procedure to attempt to rebuild the channel with the downstream acquisition and control circuit;

[0054] If reconstruction fails, the teletransmission stub switches to degraded mode, only reporting abnormal status frames to the ground system and ceasing subsequent command distribution.

[0055] As a preferred technical solution, the method supports adjusting the multi-probe strategy according to the well section structure, specifically including:

[0056] If a strong absorption layer is identified in the strata, the control algorithm switches to a "near-far" coupled sampling mode, and at the same time widens the sampling windows of the first and second detectors to cover the transition zone.

[0057] If the well section is identified as a fractured sandstone layer, the "far-ultra-far" delayed sampling mode is activated, focusing on recording the attenuation trend of the time spectrum in the middle and later stages of the third detector;

[0058] All three probe data are synchronized and aligned according to a unified time axis, and undergo collaborative correction processing, serving as the input for the comprehensive inversion of oil, water, and gas saturation.

[0059] Beneficial effects

[0060] 1. In the data acquisition stage, Ming introduced a combined preprocessing strategy of window sliding integral, energy spectrum layered filtering and abnormal pulse shielding, which for the first time transformed the raw signals from multiple probes into structured measurement subframes in real time downhole.

[0061] This improvement eliminates the need for post-processing removal of spectral noise at the ground-based solution end. Instead, it enables dynamic removal and multi-dimensional compression at the data acquisition source, thus ensuring high-confidence spectral quality in the downhole environment. This method avoids the frequent frame drops or waveform distortion problems caused by limited data transmission bandwidth in traditional technologies, ensuring that uploaded data has a unified format and complete labels, greatly improving the accuracy and efficiency of ground-based inversion calculations.

[0062] 2. By designing a compensation sampling logic, when the detector has an excessively high sampling rate, a dual compensation strategy of extending the sampling window and lowering the voltage threshold is automatically triggered, supplemented by a redundant channel sampling mechanism.

[0063] This improvement overcomes the limitations of existing logging methods that rely solely on fixed windows and single-channel counting, maintaining a stable signal-to-noise ratio and traceable spectral data in high-temperature, high-pressure, high-noise, and low-signal well sections. In particular, the introduction of delayed backoff and compensation channel coordination not only enhances the continuity and tolerance of the detector under extreme conditions but also enables adaptive recovery from abnormal states, ensuring high consistency and integrity of logging data in continuous long-section measurements.

[0064] 3. In terms of communication links and data upload, Ming proposed a priority frame scheduling and abnormal log reporting mechanism, which divides the main logging frames and monitoring frames into different levels and routes, and provides short-format redundant frame upload when the link is abnormal.

[0065] This improvement enables the system to retain critical spectral and equipment status information even in the event of sudden channel packet loss or interference, achieving multi-dimensional fault tolerance and data redundancy. Through this mechanism, the present invention not only outperforms traditional solutions in terms of real-time performance and stability, but also exhibits extremely high robustness in the unpredictable downhole operating environment, ensuring the reliability and repeatability of the comprehensive oil and gas saturation measurement results. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the formation element saturation measuring instrument involved in this invention;

[0067] Figure 2 This is a schematic diagram of the control method of the present invention;

[0068] Figure 3 The non-elastic spectrum of the near-detector of this invention;

[0069] Figure 4 This refers to the non-elastic spectrum of the remote detector of the present invention. Detailed Implementation

[0070] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0071] Example 1

[0072] This embodiment is an improvement based on the applicant's prior art CN215369811U, and focuses on the control method of the formation element saturation measuring instrument involved.

[0073] This embodiment provides a TNIS Plus control method for thermal neutron imaging saturation logging, applied to a formation element saturation measuring instrument, comprising a remote transmission sub, a data acquisition sub, and a high-pressure control sub connected in sequence, such as... Figure 1 As shown, it is used to achieve high-precision, multi-dimensional, and structured measurement of water, oil, and gas saturation in formations.

[0074] This method revolves around formation response characteristics, detector configuration, time synchronization control, data preprocessing, and anomaly self-recovery mechanisms, forming a multi-probe logging control process with time logic closed loop, data quality verification, and intelligent sampling adaptive capabilities. Specific steps are as follows: Figure 2 As shown.

[0075] In step S1, before the logging operation is started, the surface system issues a start command through the console interface. The remote transmission sub, as the downhole main control module, first receives the command and initializes it.

[0076] The initialization process includes: configuring the communication baud rate and establishing a dedicated communication channel with the downstream acquisition sub and high-pressure control sub; executing the handshake protocol and self-test process; loading the operation template matching the current well section; automatically recording the system time and generating a globally unique task sequence number. The task sequence number is embedded in the header of all subsequent uploaded data packets to ensure that the surface system can trace and distinguish logging data from multiple well sections and cycles.

[0077] In step S2, the remote transmission short-section scheduling magnetic positioning component starts operation, detects the position of the coupling in the drilling casing structure, and achieves high-precision depth positioning by identifying its unique magnetic anomaly.

[0078] Subsequently, the temperature and pressure module is activated, acquiring the ambient temperature and pressure of the well section at 200ms intervals. To ensure that the logging parameters are consistent with the actual physical state of the formation, the system sends the magnetic positioning results, temperature, and pressure data to the magnetic temperature calibration module, constructing a linear fitting function within a 3-second window, identifying interfering data, and performing standardized corrections. If the fitting residual exceeds a set threshold (e.g., ±5%), the acquisition is deemed invalid, triggering the module to resample, ensuring the reliability of the positioning and environmental parameter data.

[0079] In step S3, after completing the depth and environment calibration, the system enters the neutron emission control phase.

[0080] First, the high-voltage power supply module is initialized by the high-voltage control subsection, outputting an initial target voltage (e.g., 25kV) and hot wire current (e.g., 1.5A) to preheat the neutron source.

[0081] Once the system reaches a stable state, the control unit generates a matching pulse emission timing curve based on the pre-loaded geological inversion model and well depth segmentation information, determining the pulse width, pulse interval, sequence length, and energy distribution coefficient. Subsequently, the high-voltage control circuit precisely controls the rising edge, duration, and falling curve of the anode high voltage according to this timing, completing the high-energy excitation of neutrons and beam targeting within the emission window. Approximately 15ms after neutron emission, the voltage is automatically reduced to a safe value to prevent residual hot wire burnout or ionization overheating.

[0082] In step S4, after the high-voltage control subsection receives the timestamp of the neutron target impact event, it immediately enters the three-probe acquisition trigger mode.

[0083] The first detector, acting as a near-field detector, has a sampling window set to 1–100 μs, focusing on capturing information about the initial thermalization process of neutrons. Its non-elastic spectrum is as follows: Figure 3 As shown;

[0084] The second detector is a remote detector, with two consecutive windows: a 1–50 μs inelastic window and a 50–300 μs capture window, used to construct the energy spectrum response characteristics. Its inelastic spectrum is as follows: Figure 4 As shown;

[0085] The third detector, as an ultra-long-range detector, has a sampling window set to 300–800 μs to capture the delayed response after deep neutron capture.

[0086] The length of each window can be dynamically adjusted based on real-time temperature changes and the stratigraphic absorption coefficient model. This multi-window structure ensures that neutron behavior at different depths and response velocities can be fully sampled and covered under complex reservoir conditions.

[0087] In step S5, the high-pressure control sub activates the downhole pretreatment mechanism.

[0088] First, a sliding integration operation is performed on the neutron time spectrum data. The time axis is divided into multiple sliding windows of fixed width (e.g., 10 μs). The cumulative count events within each window generate an integration point sequence, which is used for subsequent inversion of water saturation.

[0089] Next, the system performs layered processing on the gamma spectrum data, dividing the original spectrum into the inelastic region (0–1 MeV), the trapping region (1–4 MeV), and the excitation region (>4 MeV) according to the energy range. Differentiated bandpass filtering and statistical elimination algorithms are applied to each region to enhance the main peak of the spectrum and suppress tail noise and thermal noise components.

[0090] To address noise and anomalous signals, the system constructs a two-dimensional statistical model of pulse amplitude and width, identifies anomalous pulses (such as amplitudes exceeding the mean by ±3σ), performs masking and removal, and records anomaly event indices for subsequent quality analysis. After processing, all spectral data, detector identifiers, timestamps, and sampling numbers are uniformly packaged into structured measurement subframes with complete fields, a fixed format, and embedded check bits, suitable for link uplink and ground-based calculations.

[0091] In step S6, all measurement subframes are cached and integrated, and then enter the data frame encapsulation process.

[0092] The encapsulation strategy employs a dual-channel priority scheduling mechanism, dividing the data into main frames (for content calculation) and monitoring frames (for device status analysis).

[0093] The main frame contains key information such as spectral summary, detector number, and layer label; the monitoring frame contains operating parameters such as temperature, voltage, current, and waveform integrity. The teletransmission circuit reports in a time-division manner according to frame type and buffer priority, and performs parallel unpacking at the ground receiving end.

[0094] Step S7 is the abnormal compensation control process. When the high-voltage control sub-section detects that the number of effective pulses per unit cycle of a detector is lower than the set lower limit (e.g., 500 count), it is determined to be in a no-sampling state, and the compensation logic is automatically started.

[0095] First, the sampling window is extended (e.g., +100μs), and second, the voltage threshold is lowered to enhance the ability to detect weak signals. The acquisition circuit simultaneously starts dual-channel sampling of the main channel and the compensation channel, and the two are recorded separately and distinguished by a flag bit.

[0096] Compensation data participates in spectral model construction but is not directly entered into the inversion model. If the no-sampling state is not restored for three consecutive cycles, the system switches the detector to delayed backoff mode, pausing the main channel for 5 seconds and only retaining the low-speed channel to continue sampling.

[0097] In step S8, the teletransmission stub maintains the frame reception status record table in real time, and the timestamps of all detector uploaded frames are cached for link health assessment.

[0098] If any detector fails to upload any valid frame for 5 consecutive seconds, the system determines that the link is abnormal and immediately triggers the soft reconnection mechanism to attempt to rebuild the communication channel. If the rebuild fails, it switches to degrade mode, allowing only the teletransmission segment to upload alarm information frames and blocking all downward command channels to prevent signal accumulation.

[0099] In addition to the main process described above, this embodiment also supports adaptive detector mode switching. When the target layer is identified as a strong absorption layer, it automatically switches to the "near-far" coupling mode, extending the windows of the first and second detectors to enhance cross-layer signal coverage. If it is fractured sandstone, the system favors the "far-ultra-far" mode, emphasizing the delayed response capability of the third detector.

[0100] All detector data are aligned along a unified time axis and input into a co-calibration module to ensure the accuracy of the spectral shape in both time and intensity dimensions.

[0101] In summary, this embodiment constructs a TNIS Plus control process that features multi-module collaboration, time synchronization, unified data structure, and anomaly adaptation. This enables accurate, stable, and traceable measurement of water, oil, and gas saturation under complex well conditions, significantly improving the application capabilities of the thermal neutron logging system in terms of intelligence, robustness, and data integrity.

[0102] Example 2

[0103] This embodiment provides a thermal neutron imaging saturation logging TNIS Plus control method, which is applied to a logging system consisting of a remote transmission sub, an acquisition sub, and a high-pressure control sub, to achieve high-precision, multi-dimensional, and structured measurement of water, oil, and gas saturation in the formation.

[0104] This method is built around formation response characteristics, detector configuration, time synchronization control, data preprocessing, and abnormal state self-recovery mechanism, forming a multi-probe logging control process with time logic closed loop, data quality verification, and intelligent sampling adaptive capabilities.

[0105] In step S1, before the logging operation is started, the surface system issues a start command through the console interface. The remote transmission sub, as the downhole main control module, first receives the command and initializes it.

[0106] The initialization process includes: configuring the communication baud rate, establishing a dedicated communication channel with the downstream acquisition sub and high-pressure control sub; executing the handshake protocol and self-test process; loading the operation template matching the current well section; automatically recording the system time and generating a globally unique task sequence number.

[0107] The task sequence number is embedded in the header of all subsequent uploaded data packets to ensure that the ground system can trace and distinguish logging data from multiple well sections and multiple cycles.

[0108] In step S2, the remote transmission short-section scheduling magnetic positioning component starts operation, detects the position of the coupling in the drilling casing structure, and achieves high-precision depth positioning by identifying its unique magnetic anomaly.

[0109] Subsequently, the temperature and pressure module was activated, acquiring the ambient temperature and pressure of the well section at a period of 200ms. To ensure that the logging parameters are consistent with the actual physical state of the formation, the system sends the magnetic positioning results, temperature and pressure data to the magnetic temperature calibration module, constructs a linear fitting function within a 3-second window, identifies interfering data, and performs standardized correction.

[0110] If the fitting residual exceeds the set threshold (e.g., ±5%), the current acquisition is deemed invalid, triggering the module to resample to ensure the reliability of the positioning and environmental parameter data.

[0111] In step S3, after completing the depth and environment calibration, the system enters the neutron emission control phase.

[0112] First, the high-voltage power supply module is initialized by the high-voltage control sub, outputting an initial target voltage (e.g., 25kV) and hot wire current (e.g., 1.5A) to preheat the neutron source. Once the system reaches a stable state, the control unit generates a matching pulse emission timing curve based on the pre-loaded geological inversion model and well depth segmentation information, determining the pulse width. Pulse interval Sequence length Energy distribution coefficient .

[0113] in, Based on the corresponding neutron capture section of the well section With diffusion coefficient Dynamically determined, satisfying:

[0114] ,

[0115] in, This is an empirical adjustment factor, typically taken as a value of... The parameters control the minimum time interval required for thermal neutrons to diffuse from the source region to the detector region, thereby avoiding overlapping interference from multiple emissions. The neutron absorption cross section, denoted by Σa, is a comprehensive measure of the neutron absorption capacity of all atoms per unit volume of material, measured in units of... The absorption probability per centimeter of path length; satisfying:

[0116] ,

[0117] Where N is the number density of target nuclei in the volume (nuclei / cm³). To verify the microscopic capture cross section of neutrons, the unit is... , ( The capture cross-sections of common geological elements are shown in Table 1:

[0118] ,

[0119] In step S4, the high-voltage control subsection synchronously starts the detector acquisition window according to the neutron emission timestamp T0T_0T0:

[0120] First detector The sampling interval is ;

[0121] Second detector Split into non-pop-up window With capture window ;

[0122] Third detector use The delay window.

[0123] All detector channels are equipped with analog-to-digital converters (ADCs) for periodic sampling, with a sampling frequency set to [value missing]. Each channel output forms There are 10 data points; among them, This is the sampling window width, i.e., the duration for which the detector starts collecting data;

[0124] In S5, the detection data undergoes downhole preprocessing.

[0125] First, perform a sliding integration operation on the time-series signal of each detector: given the integration window width. ,exist Then perform continuous window sliding integration:

[0126] ,

[0127] in, Indicates the detector at time The intensity of the acquired neutron response signal is counted as voltage peaks or pulses; 𝑘 is the index number of the sliding window, indicating which time period window is currently in use.

[0128] Obtain the integral sequence Secondly, the energy spectrum is processed into layers: the original energy spectrum. Divided into three sections , and , respectively representing the non-ballistic, captured, and activated zones;

[0129] Each signal pulse below the background noise level is removed using dual-threshold filtering, satisfying the following conditions:

[0130] ,

[0131] in, Let be an interval indicator function that satisfies:

[0132] ,

[0133] Subsequently, abnormal pulse rejection is determined using the following formula:

[0134] ,

[0135] in, For the first Each pulse amplitude, and These represent the mean and standard deviation of the pulse amplitude, respectively.

[0136] Finally, all valid pulses are encapsulated into structured measurement subframes according to detector number, timestamp, and energy spectrum tag. It features multi-field validation and link synchronization control codes.

[0137] In step S6, all Subframes entering the telemetry circuit are divided according to their frame attributes as follows:

[0138] Main frame: ,in, A spectral summary;

[0139] Monitoring frames: These are voltage, temperature, health status, and sampling integrity, respectively.

[0140] The scheduler controls the uploading of frames with different priorities at asynchronous bit rates. High-priority frames are transmitted with an 8-bit frame width, while low-priority frames are transmitted at a reduced bit rate of 4 bits to avoid link congestion.

[0141] If in step S7 Effective pulse count The system determines the no-sampling status and executes the following logic:

[0142] 1. Extend the sampling window: ;

[0143] 2. Adjust the voltage threshold: ;

[0144] 3. Activate the compensation channel and record the data;

[0145] 4. If there are three consecutive abnormal cycles, the main channel will sleep for 5 seconds, and the compensation channel will reduce the sampling rate to maintain low-frequency monitoring;

[0146] In S8, the real-time statistics of the frame upload interval per channel in the teletransmission short section are as follows: ,like The link reconstruction process is executed, with a maximum of 3 retries. If it fails, it enters alarm mode and sends a simplified frame structure.

[0147] ,

[0148] Write to the diagnostic log.

[0149] Supports adjusting multi-probe strategies based on well section structure, specifically including:

[0150] If a strong absorption layer is identified in the strata, the control algorithm switches to a "near-far" coupled sampling mode, and at the same time widens the sampling windows of the first and second detectors to cover the transition zone.

[0151] If the well section is identified as a fractured sandstone layer, the "far-ultra-far" delayed sampling mode is activated, focusing on recording the attenuation trend of the time spectrum in the middle and later stages of the third detector;

[0152] All three probe data are synchronized and aligned according to a unified time axis, and undergo collaborative correction processing, serving as the input for the comprehensive inversion of oil, water, and gas saturation.

[0153] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling a thermal neutron imaging saturation logging (TNIS Plus), applied to a formation element saturation measuring instrument, comprising a remote transmission sub, a collection sub and a high-voltage control sub connected in sequence; characterized in that The method comprises the following steps: S1.A ground system issues a start instruction, and the remote transmission sub receives the instruction, initializes a communication channel with each logging sub-module, records an initialization time stamp and assigns a task sequence number simultaneously; S2.The remote transmission sub schedules a magnetic positioning assembly to perform a casing collar positioning operation, acquires a well depth reference position parameter, and performs magnetic temperature standardization calibration on logging operation parameters of this time according to temperature and pressure data; S3.After the position parameter is confirmed, the neutron generator emits a thermal neutron beam according to a preset neutron emission pulse time sequence, and the pulse time sequence curve is determined by a control algorithm according to well depth segmentation characteristics and a formation inversion model, and the high-voltage unit provides an anode pulse voltage according to a set target pressure waveform; S4.The high-voltage control sub triggers a time sequence collection window of the first detector, the second detector and the third detector respectively according to a neutron emission event time stamp, and the collection window length is related to a neutron lifetime, a layer position absorption characteristic and an environmental temperature; S5.The high-voltage control sub pre-processes data collected by the detector, including time spectrum window sliding integration, energy spectrum layering filtering and abnormal pulse shielding processing, and generates a structured measurement sub-frame; S6.Every measurement sub-frame is bound with a detector type, a layer position label and an emission sequence number one by one, packaged as a logging data frame, and uploaded to the ground system through a remote transmission circuit layer by layer after being buffered; S7.During the collection process, if a certain detector exceeds a preset empty collection rate threshold, a compensation sampling logic is automatically triggered, the sampling window of the detector is extended and the voltage threshold is adjusted to improve the signal-to-noise ratio and ensure the spectral shape quality; S8.The remote transmission sub monitors the on-off state and abnormal code of the data link of the three detectors in real time, when continuous multiple frames are lost, a short format alarm frame is sent through a redundant channel, and an alarm log and a time stamp are recorded and uploaded to the ground system.

2. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, In S3, the neutron emission pulse time sequence comprises the following parameters: pulse width, pulse interval, sequence length and energy distribution coefficient; wherein the pulse interval is dynamically adjusted according to the neutron capture cross section statistical value of different well sections, the pulse width is adjusted according to the target voltage and the preheating state of the hot wire, and the sequence length is adjusted according to the target layer position predetermined sampling confidence level.

3. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, In S4, the collection window is defined according to the detector type: the window corresponding to the first detector is within 1-100 μs after the neutron is targeted; the window corresponding to the second detector is divided into a non-elastic window of 1-50 μs and a capture window of 50-300 μs; the window corresponding to the third detector is a continuous interval of 300-800 μs.

4. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, The pre-processing in S5 comprises the following steps: S51.A sliding integration operation is performed on the neutron time spectrum data, specifically: on the time axis starting from the neutron emission reference time, an equal interval sliding is performed in a preset time window, the counting events in each sliding window are integrated, a discretized time spectrum integral sequence is generated, the time window is determined according to the detector type and the neutron lifetime constant, and the integral sequence is used for subsequent water saturation inversion. S52, layered filtering is performed on the gamma spectrum data, specifically, a pre-defined spectrum hierarchy is established according to different energy sections, the original spectrum is divided into three energy sections of non-elastic section, capture section and excitation section, a band-pass filter and a statistical threshold rejection algorithm are applied to each energy section respectively, the main peak of the spectrum is retained and the tail noise component is suppressed, and the filtered multi-section spectrum is used for oil content feature recognition and carbon-oxygen ratio calculation; S53, shielding is performed on the abnormal pulse in the detector output signal, specifically, whether the pulse width and amplitude meet the statistical distribution expected value range is detected, the abnormal pulse is marked as an invalid value by using upper and lower limit rejection rules, and is removed from the original data set; meanwhile, an abnormal event index table is constructed to mark the abnormal frequency and acquisition quality level within the time period; S54, the processed time spectrum integration sequence is combined with the spectrum multi-section feature data, detector identifier, time stamp, and sampling sequence number metadata to be packaged as a structured measurement sub-frame; The measurement sub-frame is a data structure with a fixed format, has a check bit and a sequence control field, and is suitable for data synchronization processing required by the on-transmission link and ground inversion solver; S55, after each measurement period ends, the measurement sub-frames generated by all the detectors in the period are cached and integrated to enter the data frame packaging and uploading process.

5. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 4, wherein, In S55, the data frame packaging and uploading process adopts a priority scheduling mechanism, including: The logging frame is divided into a high-priority main frame and a low-priority monitoring frame; The high-priority main frame includes the detector number, time label, spectrum summary information and well section identifier; The low-priority monitoring frame includes device temperature, voltage, current and detector health status; The two types of frames are asynchronously uploaded at different bit rates through a time-division multiplexing strategy.

6. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, Step S7 specifically includes: S71, the high-voltage control short section continuously monitors the valid pulse count value of each detector in the unit sampling period, calculates the proportion of the value relative to the standard pulse reference value, and if the proportion is lower than the set effective rate lower threshold, it is judged that the detector is currently in the high air sampling rate state; S72, after detecting the high air sampling state, the high-voltage control short section issues a sampling window adjustment instruction to the detector, the instruction includes a parameter value of an extended time length, the sampling window is extended by the extended time length based on the original sampling period, and the value of the extended time length is determined according to the response delay average of the layer where the detector is currently located; S73, the high-voltage control short section sends a gain adjustment instruction to the front-end analog-to-digital conversion channel, adjusts the signal voltage threshold of the sampling circuit of the detector from the original threshold voltage to the enhanced threshold voltage in the enhanced state, the enhanced threshold voltage is less than the original threshold voltage, and the enhanced threshold voltage is determined based on the joint fitting results of the noise ground distribution and the signal peak frequency density in the previous period; S74, during the compensation sampling, the high-voltage control short section enables multi-channel redundant sampling, records the main channel data and compensation channel data respectively, and adds an identification field to distinguish the original sampling and compensation data; S75, after completing the compensation sampling, the two types of data are merged into a time axis alignment process, and a unified spectrum shape construction and spectrum section screening operation is performed by the subsequent preprocessing module; S76, if the empty fraction of the probe is still higher than the lower threshold of the effective fraction for three consecutive periods, the high-voltage control short section enters a delayed retreat state, suspends the main channel sampling of the probe for 5 seconds, and only retains the low-speed sampling path of the compensation channel as a backup data sampling strategy during this period, in order to reduce the system load and protect the stability of the spectrum shape quality.

7. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, The magnetic temperature standardization calibration performed by the remote short section in S2 adopts a synchronous sampling mechanism, specifically including: The magnetic positioning signal is performed within a 50ms window after the metal disturbance of the drilling pipe string subsides; Temperature and pressure data are collected at a period of 200ms, and a linear fitting function is constructed within 3 seconds; If the fitting residual exceeds the set error threshold, the measurement is discarded as invalid, and resampling is performed; The obtained valid value is encapsulated in JSON structure as additional header information of the logging frame and uploaded.

8. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, The anode voltage control process of the high-voltage control short section includes: In the initialization stage, the high-voltage power supply module outputs the initial target pressure and the hot wire preheating current; 15ms before emission, the high-voltage control circuit raises the target pressure to the target target pressure, and completes the neutron emission within the maintenance time; After the neutron emission is completed, the anode voltage is restored to a safe anode voltage through a preset decay curve to avoid residual hot wire burning; All voltage and current state parameters are recorded by the control circuit and embedded as additional parameters in the uploaded frame.

9. The Thermal Neutron Imaging Saturation Logging (TNIS Plus) control method of claim 1, wherein, The remote short section monitoring mechanism includes the following processes: Real-time maintenance of timestamp-based frame receiving record cache; If no acquisition sub-frame is received for more than 5 seconds, it is counted as a link exception; Start the soft reconnection program to try to rebuild the channel with the downstream acquisition control circuit; If the reconstruction fails, the remote short section switches to a degraded mode, only reports abnormal state frames to the ground system, and stops subsequent command distribution.

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