A method for locating downhole leakage points based on microchip measurement data

Abstract

This invention relates to a method for locating downhole leakage points based on microchip measurement data. The method includes the following steps: acquiring raw temperature measurement data of the entire wellbore through on-site microchip testing; converting the raw measurement data into temperature-to-depth data; performing noise reduction processing on the temperature-to-depth data to obtain temperature gradient-to-depth data; differentiating the noise-reduced temperature gradient-to-depth data again to obtain temperature gradient change-to-depth data and forming a temperature gradient change curve; and determining the leakage point based on the temperature gradient change curve. This method uses a small-sized microchip, allowing for full-wellbore temperature field measurement without affecting the drilling process. Furthermore, by retrieving and processing the measured data to obtain full-wellbore temperature gradient change data, combined with a downhole heat conduction model, the leakage point can be quickly located.

Description

Technical Field

[0001] This invention belongs to the field of drilling technology, and in particular relates to a method for locating downhole leakage points based on microchip measurement data. Background Technology

[0002] In drilling operations, lost circulation (WS) is a serious and complex field condition that can lead to significant waste of drilling fluid and field time, resulting in substantial economic losses. Severe WS can cause a drop in well pressure, affecting normal drilling, causing wellbore instability, inducing formation fluid inrush into the wellbore, and leading to blowouts—all serious safety issues. Based on the severity of the loss, WS is classified into several levels: seepage, partial loss, and severe loss. Seepage is the mildest form of WS, with a loss rate below 10 barrels / hour (1.6 cubic meters / hour). This type of loss is generally caused by drilling fluid entering the formation pores rather than fractures. Seepage is often related to the loss of drilling mud into the formation's pore network system before filter cake formation. The seepage rate is closely related to overbalanced pressure and rock permeability.

[0003] Partial loss refers to a drilling fluid loss rate of 10-100 barrels / hour (1.6-16 cubic meters / hour). In this case, the driller needs to carefully consider whether to continue drilling or take remedial measures.

[0004] Severe wellbore leakage occurs when drilling fluid enters the formation through fractures, cavities, or sinkholes at a rate exceeding 16 cubic meters per hour. This includes complete loss of drilling fluid, meaning no drilling fluid returns to the surface. The consequences of such accidents can include well control failures and dry drilling accidents, where drilling continues after complete fluid loss, leading to damage to the drill bit, drill string, or wellbore.

[0005] Therefore, once a downhole leak is discovered, on-site plugging operations need to be carried out as soon as possible to minimize the impact of the leak. The first step in plugging operations is to locate the leak point. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this invention is to provide a method for locating downhole leakage points based on microchip measurement data. This method enables rapid and low-cost on-site measurement and leakage point calculation and location, and can be widely applied in drilling and plugging operations.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for locating downhole leakage points based on microchip measurement data, comprising the following steps:

[0009] Raw temperature measurement data of the entire wellbore was obtained through on-site testing using microchips.

[0010] Convert the raw measurement data into data corresponding to temperature and well depth;

[0011] The temperature-corresponding well depth data is denoised to obtain temperature gradient-corresponding well depth data;

[0012] The well depth data corresponding to the temperature gradient in the noise reduction process are differentiated again to obtain the well depth data corresponding to the temperature gradient change and form a temperature gradient change curve;

[0013] The leak point is determined based on the temperature gradient change curve.

[0014] Preferably, the noise reduction processing of the temperature-corresponding well depth data includes smoothing the temperature-corresponding well depth data.

[0015] Preferably, the smoothing process includes the following steps:

[0016] Import the temperature data of the microchip after deep calibration calculation;

[0017] Choose a smoothing method;

[0018] Select the number of time points for data smoothing;

[0019] A data smoothing algorithm is initiated for the depth calibration data of each microchip to reduce noise and obtain smooth data.

[0020] The preferred method for determining the leak point based on the temperature gradient change curve includes:

[0021] When the temperature gradient change is less than zero, the temperature of the drilling fluid gradually increases as it moves upward, indicating that the leak point occurs in the lower annulus.

[0022] When the temperature gradient change is greater than zero, the temperature of the drilling fluid gradually decreases as it moves upward, indicating that the leak point is located in the upper annulus.

[0023] When the temperature gradient curve shows a significant positive abrupt change, it indicates that the liquid in the annulus is either cooling rapidly or heating up slowly, thus indicating that the leak is located in the annulus section.

[0024] Preferably, the range of data variation after smoothing is within 0.01℃ / ft.

[0025] In a second aspect, the present invention provides a device for locating downhole leakage points based on microchip measurement data, comprising:

[0026] The first processing unit is used to obtain raw measurement data of the temperature of the entire wellbore through on-site testing with a microchip.

[0027] The second processing unit is used to convert the raw measurement data into data corresponding to the well depth at the temperature.

[0028] The third processing unit is used to perform noise reduction processing on the temperature-corresponding well depth data to obtain temperature gradient-corresponding well depth data.

[0029] The fourth processing unit is used to differentiate the well depth data corresponding to the temperature gradient in the noise reduction process again to obtain the well depth data corresponding to the temperature gradient change and form a temperature gradient change curve.

[0030] The fifth processing unit is used to determine the leak point based on the temperature gradient change curve.

[0031] Thirdly, the present invention provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the method for locating downhole leakage points based on microchip measurement data.

[0032] Fourthly, the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the method for locating downhole leakage points based on microchip measurement data.

[0033] The present invention has the following advantages due to the adoption of the above technical solutions:

[0034] The present invention provides a method for locating downhole leakage points based on microchip measurement data. This method uses a small-sized microchip to measure the temperature field of the entire wellbore without affecting the drilling process. In the later stage, by recovering and processing the measured data to obtain the temperature gradient change data of the entire wellbore, and combining it with the downhole heat conduction model, the leakage point can be quickly located.

[0035] No need to trip the drill bit, saving a lot of time and labor costs. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0037] In the attached diagram:

[0038] Figure 1 This is a flowchart of the microchip workflow;

[0039] Figure 2 This is a flowchart of the smoothing process;

[0040] Figure 3 This is a graph of microchip temperature measurement data after depth calibration calculation;

[0041] Figure 4 It is a smoothed temperature gradient curve;

[0042] Figure 5 It is a temperature gradient curve after further processing using the simple moving average method;

[0043] Figure 6 This is the temperature gradient curve after further processing using the weighted moving average method;

[0044] Figure 7 These are three sets of microchip temperature gradient curves calculated using the simple moving average method (left) and the weighted moving average method (right). Detailed Implementation

[0045] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0046] This invention provides a method for locating downhole leakage points based on microchip measurement data, comprising the following steps: acquiring raw temperature measurement data of the entire wellbore through on-site microchip testing; converting the raw measurement data into temperature-to-depth data; performing noise reduction processing on the temperature-to-depth data to obtain temperature gradient-to-depth data; differentiating the noise-reduced temperature gradient-to-depth data again to obtain temperature gradient change-to-depth data and forming a temperature gradient change curve; and determining the leakage point based on the temperature gradient change curve. This method uses a small-sized microchip, enabling full-wellbore temperature field measurement without affecting the drilling process. Furthermore, by retrieving and processing the measured data to obtain full-wellbore temperature gradient change data, combined with a downhole heat conduction model, the leakage location can be quickly identified.

[0047] Example 1

[0048] The method for locating downhole leakage points based on microchip measurement data provided by the present invention specifically includes the following steps:

[0049] S1. Obtain the original temperature measurement values ​​of the entire wellbore through on-site testing using a microchip, such as... Figure 1 As shown;

[0050] A downhole measurement microchip (also known as a traveling data acquisition unit) is a miniature spherical or capsule-shaped instrument containing a microcontroller, memory, sensors, a data transmission module, and a miniature rechargeable lithium battery. All circuits and components are encased in a spherical or capsule-shaped protective material, and the entire system has a diameter of approximately 8-12 mm. The protective material used in the microchip possesses extremely high strength and glass transition temperature, ensuring that its internal circuits and components can withstand the high temperature and pressure environment downhole. Figure 1 As shown.

[0051] In actual drilling operations, the downhole measurement microchip is activated and inserted into the drill pipe. It circulates with the drilling fluid to the bottom of the well, is ejected from the drill bit's water inlet, enters the annulus, returns upwards to the surface, and is finally retrieved by a vibrating screen. Throughout this process, the downhole measurement microchip continuously measures important downhole parameters such as temperature and pressure. After retrieval, the microchip's data can be read using specialized equipment.

[0052] S2. Convert the raw measurement data into data corresponding to the temperature and well depth;

[0053] S3. Perform noise reduction processing on the temperature-corresponding well depth data to obtain temperature gradient-corresponding well depth data;

[0054] S4. Differentiate the well depth data corresponding to the temperature gradient in the noise reduction process again to obtain the well depth data corresponding to the temperature gradient change and form a temperature gradient change curve.

[0055] S5. Determine the leak point based on the temperature gradient change curve.

[0056] The noise reduction process for the temperature-corresponding well depth data includes smoothing the temperature-corresponding well depth data.

[0057] There are several methods to smooth the measurement data from microchips, such as simple moving averages and weighted moving averages. During data processing, the length of the moving average period (referring to the number of measured data points, which should ideally be an odd number in practice) needs to be specifically set. For example, data with 5 periods is smoothed by averaging the first two data points, the last two data points, and the data point itself (2+1+2) using a moving average algorithm. The calculated data then replaces the original data. Using this method, once the temperature-to-depth data of the entire microchip is smoothed, we can calculate the actual annular temperature gradient (dT / dZ).

[0058] In past data processing, microchip measurement data has never been smoothed. Unsmoothed data has greater noise and fluctuations, which can greatly affect the accuracy of subsequent data analysis and interpretation.

[0059] The noise reduction process specifically includes the following steps, such as... Figure 2 As shown:

[0060] S3-1. Import the data processed by the microchip after depth calibration calculation;

[0061] S3-2. Select and configure relevant settings (such as data smoothing method and units); the units refer to the units of the input parameters. For example, well depth may be in metric units (meters) or imperial units (feet); temperature units may be Celsius or Fahrenheit. Therefore, the units need to be selected correctly.

[0062] S3-3. Select the number of time points for smoothing the data;

[0063] S3-4. Start the smoothing data algorithm for the depth calibration data of each microchip to obtain the measured value of temperature corresponding to well depth after smoothing.

[0064] S3-5. After smoothing, select the temperature data corresponding to the well depth in the annulus section and differentiate to obtain the temperature gradient dT / dZ.

[0065] The temperature gradient change is obtained by taking the derivative of the temperature gradient again.

[0066] The temperature gradient change is smoothed again;

[0067] Plot the smoothed temperature gradient change corresponding to the well depth on the coordinate graph.

[0068] A negative temperature gradient indicates that the drilling fluid is being heated as it rises in the annulus, typically occurring in the lower part of the annulus, near the bottom of the well. Conversely, a positive temperature gradient indicates that the drilling fluid is being cooled as it rises in the annulus, typically occurring in the upper part of the annulus, near the surface. The annulus refers to the ring-shaped space within the wellbore, specifically the annular space outside the drill pipe and inside the wellbore. The magnitude of the annular temperature gradient changes, after data processing, can be used to diagnose and locate anomalies in downhole temperature variations. Theoretically, a significant temperature gradient change at a certain location may indicate anomalies in the downhole at that location, such as changes in lithology or geothermal gradients, wellbore irregularities, or lost circulation. Possibilities such as changes in lithology or geothermal gradients and wellbore irregularities can be ruled out by analyzing data from actual cases, thereby confirming the existence of downhole lost circulation problems and locating the location of the leakage.

[0069] Example 1

[0070] Taking test well 1 as an example, it is worth noting that a slight or partial leakage was found in this well. Therefore, a microchip was used for on-site testing in an attempt to analyze and locate the actual leakage point using the measurement data from the microchip.

[0071] The microchip temperature measurement data after deep calibration calculation is as follows: Figure 3 As shown in the figure, the differences between the measurement data of different microchips are all within 2℃.

[0072] When smoothing microchip measurement data using different numbers of moving average periods (e.g., 5, 11, 15, 21), fewer periods result in higher noise levels in the processed data; conversely, more periods result in smoother data. Therefore, in actual smoothing, a total of 21 periods were used. Based on a microchip sampling frequency of one data point every 2 seconds, this is equivalent to averaging 20 seconds of data before and after each data point. The calculated results are as follows: Figure 4 As shown.

[0073] The average temperature gradient curve shows that noise remains significant at certain points. Therefore, further processing of the temperature measurement data is necessary. Specifically, the temperature gradient should be calculated using both the simple moving average method and the weighted moving average method, each with 21 periods. The results are as follows: Figure 5 and Figure 6 As shown. Among them. Figure 5 This is the temperature gradient curve after processing using the simple moving average method. Figure 6 This is the temperature gradient curve after processing using the weighted moving average method.

[0074] Using a simple moving average method can effectively remove noise from temperature gradient calculation data. The average fluctuation range of dT / dZ in the data is 0.005℃ / ft; therefore, any data points with a significantly larger fluctuation range should be carefully examined to determine if they indicate downhole leakage or other anomalies. By definition, a negative temperature gradient change represents heating of the drilling fluid as it rises in the annulus. Figure 7 As shown, when the horizontal axis dT / dZ = 0, which corresponds to a well depth of approximately 6100-6200 feet, the drilling fluid temperature is highest. The graph also shows that the three sets of processed microchip measurements of the temperature gradient all exhibit significant changes at a depth of 8000 feet. This indicates a high probability of an anomaly at this location. After ruling out other wellbore irregularities and drill string malfunctions, on-site personnel can pinpoint the location of the leakage near a depth of 8000 feet.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for locating downhole leakage points based on microchip measurement data, characterized in that, Including the following steps: Raw temperature measurement data of the entire wellbore was obtained through on-site testing using microchips. Convert the raw measurement data into data corresponding to temperature and well depth; The temperature-corresponding well depth data is denoised to obtain temperature gradient-corresponding well depth data; The well depth data corresponding to the temperature gradient in the noise reduction process are differentiated again to obtain the well depth data corresponding to the temperature gradient change and form a temperature gradient change curve; Determine the leak point based on the temperature gradient change curve; The noise reduction processing of the temperature-corresponding well depth data includes smoothing the temperature-corresponding well depth data; The smoothing process includes the following steps: Import the temperature data of the microchip after deep calibration calculation; Choose a smoothing method; Select the number of time points for data smoothing; A data smoothing algorithm is initiated for the depth calibration data of each microchip to reduce noise and obtain smooth data. Determining leak points based on the temperature gradient change curve includes: When the temperature gradient change is less than zero, the temperature of the drilling fluid gradually increases as it moves upward, indicating that the leak point occurs in the lower annulus. When the temperature gradient change is greater than zero, the temperature of the drilling fluid gradually decreases as it moves upward, indicating that the leak point is located in the upper annulus. When the temperature gradient curve shows a significant positive abrupt change, it indicates that the liquid in the annulus is cooling rapidly or heating up slowly, thus indicating that the leak point is located in the annulus section. The magnitude of the temperature gradient change in the annulus after data processing is used to diagnose and locate abnormal temperature changes in the well. A change in the temperature gradient at a certain location indicates an anomaly in the well at that location, thereby determining the existence of a downhole leakage problem and locating the leakage point.

2. The method for locating downhole leakage points based on microchip measurement data according to claim 1, characterized in that, Typically, the variation range of smoothed data is within 0.01℃ / ft.

3. A device for locating downhole leakage points based on microchip measurement data, characterized in that, include: The first processing unit is used to obtain raw measurement data of the temperature of the entire wellbore through on-site testing with a microchip. The second processing unit is used to convert the raw measurement data into data corresponding to the well depth at the temperature. The third processing unit is used to perform noise reduction processing on the temperature-corresponding well depth data to obtain temperature gradient-corresponding well depth data. The fourth processing unit is used to differentiate the well depth data corresponding to the temperature gradient in the noise reduction process again to obtain the well depth data corresponding to the temperature gradient change and form a temperature gradient change curve. The fifth processing unit is used to determine the leak point based on the temperature gradient change curve; The noise reduction processing of the temperature-corresponding well depth data includes smoothing the temperature-corresponding well depth data; The smoothing process includes the following steps: Import the temperature data of the microchip after deep calibration calculation; Choose a smoothing method; Select the number of time points for data smoothing; A data smoothing algorithm is initiated for the depth calibration data of each microchip to reduce noise and obtain smooth data. Determining leak points based on the temperature gradient change curve includes: When the temperature gradient change is less than zero, the temperature of the drilling fluid gradually increases as it moves upward, indicating that the leak point occurs in the lower annulus. When the temperature gradient change is greater than zero, the temperature of the drilling fluid gradually decreases as it moves upward, indicating that the leak point is located in the upper annulus. When the temperature gradient curve shows a significant positive abrupt change, it indicates that the liquid in the annulus is cooling rapidly or heating up slowly, thus indicating that the leak point is located in the annulus section. The magnitude of the temperature gradient change in the annulus after data processing is used to diagnose and locate abnormal temperature changes in the well. A change in the temperature gradient at a certain location indicates an anomaly in the well at that location, thereby determining the existence of a downhole leakage problem and locating the leakage point.

4. A computer-readable storage medium, characterized in that, The device contains computer instructions that, when executed by a processor, implement the method for locating downhole leakage points based on microchip measurement data as described in claim 1 or 2.

5. A computer device, characterized in that, The invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, when the processor executes the computer program, it implements the method for locating downhole leakage points based on microchip measurement data as described in claim 1 or 2.

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