Working condition discrimination method for bridge plug fracturing ball seat

Abstract

The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a working condition distinguishing method for a bridge plug fracturing ball seat, which comprises the following steps: S1, collecting historical data of fracturing construction, obtaining a historical data set and drawing a construction curve; s2, intercepting a construction curve to obtain a fracturing construction curve, and extracting data feature points of the fracturing construction curve; s3, establishing judgment conditions according to the data feature points of the fracturing construction curve; and S4, the setting working condition of the ball seat is judged according to the judgment conditions. The method comprises the following steps: drawing a construction curve by collecting historical data of on-site fracturing construction, intercepting the construction curve to obtain a fracturing construction curve, extracting data characteristics of a standard fracturing construction curve when setting succeeds, and analyzing a relationship between data characteristic points during setting and whether setting succeeds or not by combining a shaft bottom mechanism, so as to establish a judgment condition; and finally, the setting working condition is monitored in real time, whether ball seat setting succeeds or not in the current fracturing construction process is judged, the fracturing efficiency is improved, and construction safety is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and is a method for determining the working condition of a bridge plug fracturing ball seat. Background Technology

[0002] Intelligent fracturing is an important development direction in petroleum engineering, and automatic identification of fracturing operation conditions is a prerequisite for realizing intelligent fracturing. Fracturing operation conditions include pressure testing, ball delivery, setting, pre-positioning, sand injection, temporary plugging, and displacement. Among these, ball delivery and setting are crucial at the start of fracturing and are primarily performed before formal fracturing operations. Fracturing bridge plugs are used to seal fractures in the horizontally fractured well section, providing a wellhead pressure sealing environment for subsequent fracturing. If the bridge plug setting fails, the current well section cannot be effectively modified, and excessive modification of the already fractured section significantly reduces the effectiveness of fracturing modification. Therefore, timely detection of whether the setting ball has successfully set when it is delivered to the bottom of the well can alert on-site engineers to adjust pumping parameters, thereby avoiding serious accidents and helping to improve fracturing efficiency and ensure operational safety.

[0003] Currently, fracturing operations mainly rely on the characteristics of wellhead pressure changes to subjectively judge the effectiveness of ball seat setting. Some atypical wellhead pressure curves are difficult to identify in real time, which has become one of the key problems restricting the success rate of horizontal well bridge plug segmented fracturing. Abnormal setting conditions are mainly reflected by wellhead pressure, and the interaction between various pumping parameters will have a significant impact on wellhead pressure. Summary of the Invention

[0004] This invention provides a method for determining the operating conditions of a bridge plug fracturing ball seat, which overcomes the shortcomings of the prior art and can effectively solve the problem that some atypical wellhead pressure curves are difficult to identify in real time when judging the effectiveness of ball seat setting.

[0005] The technical solution of the present invention is achieved through the following measures: a method for determining the working condition of a bridge plug fracturing ball seat, comprising the following steps:

[0006] S1. Collect historical data on fracturing operations, merge the historical datasets, and plot the operation curve.

[0007] S2, extract the fracturing construction curve from the construction curve, and extract the data feature points of the fracturing construction curve;

[0008] S3, establish judgment conditions based on the data feature points of the fracturing construction curve;

[0009] S4, determine the ball seat setting condition according to the judgment conditions.

[0010] The following are further optimizations and / or improvements to the above-mentioned technical solution:

[0011] Step S1 above includes the following steps:

[0012] S11, Collect historical data of fracturing operations, including time, wellhead pressure, sand concentration, bottom hole sand concentration, discharge rate, total fluid volume, total sand volume, stage fluid volume, and stage sand volume;

[0013] S12, convert the collected historical data into time series data with a time interval of 1 second, and the time series data is in xlsx format;

[0014] S13: Retain the time-series data of wellhead pressure and discharge rate before sand addition, plot the construction curves corresponding to wellhead pressure and discharge rate before sand addition, and perform outlier detection and noise reduction on the retained time-series data.

[0015] In step S13 above, the data adjacent to the outlier is replaced with the outlier, and the mean filtering method is used to denoise the retained time series data. The mean filtering method uses the following formula:

[0016]

[0017] Where, x i x represents the value of the i-th row of a column in the historical data table after noise reduction; x represents the value of a column in the fracturing data table before noise reduction.

[0018] The fracturing construction curve in step S2 above is the construction curve between the decrease in displacement before sand addition and the increase in displacement.

[0019] The data feature points in step S2 above include the wellhead pressure and displacement values ​​before the wellhead pressure surges, the wellhead pressure and displacement values ​​when the wellhead pressure reaches its peak after the surge, the wellhead pressure and displacement values ​​when the wellhead pressure drops rapidly to its trough, the wellhead pressure and displacement values ​​after the wellhead pressure rises again, and the time required from the wellhead pressure surge to the wellhead pressure rising again.

[0020] Step S3 above includes:

[0021] S31, calculate the difference between each increase and decrease in wellhead pressure and the corresponding time span;

[0022] S32, find the common wellhead pressure response characteristics of fracturing operation curves and determine the threshold of data feature points;

[0023] S33, statistically analyze the duration of the sudden rise, rapid fall and rebound of wellhead pressure and the change of wellhead pressure, and plot the curve of the change of duration and wellhead pressure.

[0024] S34, Remove outliers from the change curve, draw a judgment curve and establish judgment conditions. The judgment conditions are: when the discharge rate is stable, the wellhead pressure must simultaneously satisfy the following conditions: the slope is greater than 0.7 within 10 seconds and the slope is less than -0.4 within the next 10 seconds; when the wellhead pressure drops rapidly to the bottom, the wellhead pressure at the bottom of the valley should be greater than the wellhead pressure corresponding to the sudden rise in wellhead pressure; when the wellhead pressure rises again, the wellhead pressure slope is not greater than 0.3 and not less than zero.

[0025] The aforementioned ball seat setting conditions include successful ball seat setting and unsuccessful ball seat setting. If the judgment conditions are met, the ball seat setting is successful; otherwise, the ball seat setting fails.

[0026] This invention collects historical data from on-site fracturing operations to plot a fracturing curve, then extracts the fracturing operation curve from the plotted curve. By extracting the data features of the standard fracturing operation curve when the fracturing is successfully set, and combining this with bottom hole mechanism analysis to analyze the correlation between the data feature points at the time of setting and whether the setting is successful, a judgment condition is established. Finally, the setting condition is monitored in real time to determine whether the ball seat setting is successful during the current fracturing operation, thereby improving fracturing efficiency and ensuring construction safety. Attached Figure Description

[0027] Appendix Figure 1 This is a schematic diagram of the construction curve in this invention.

[0028] Appendix Figure 2 This is a schematic diagram of the fracturing operation curve in this invention.

[0029] Appendix Figure 3 This is a histogram of duration and wellhead pressure in this invention.

[0030] Appendix Figure 4 This is a slope variation diagram of the wellhead pressure in this invention.

[0031] Appendix Figure 5 This is a schematic diagram of the wellhead pressure curve after successful ball seat setting in this invention. Detailed Implementation

[0032] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0033] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0034] Example 1: The method for determining the operating condition of the bridge plug fracturing ball seat includes the following steps:

[0035] S1. Collect historical data on fracturing operations, merge the historical datasets, and plot the operation curve.

[0036] S2, extract the fracturing construction curve from the construction curve, and extract the data feature points of the fracturing construction curve;

[0037] S3, establish judgment conditions based on the data feature points of the fracturing construction curve;

[0038] S4, determine the ball seat setting condition according to the judgment conditions.

[0039] During the judgment process, historical data of fracturing operations at the site are collected to draw the construction curve. Then, the construction curve is extracted to obtain the fracturing construction curve. Next, the data characteristics of the standard fracturing construction curve when the setting is successful are extracted. Combined with the bottom hole mechanism analysis, the correlation between the data characteristic points at the setting and the success or failure of setting is analyzed to establish judgment conditions. Finally, the setting condition is monitored in real time to determine whether the ball seat setting is successful in the current fracturing operation, thereby improving fracturing efficiency and ensuring construction safety.

[0040] The above-mentioned method for determining the operating conditions of the bridge plug fracturing ball seat can be further optimized and / or improved according to actual needs:

[0041] Example 2: As an optimization of the above example, step S1 includes the following steps:

[0042] S11, Collect historical data of fracturing operations, including time, wellhead pressure, sand concentration, bottom hole sand concentration, discharge rate, total fluid volume, total sand volume, stage fluid volume, and stage sand volume;

[0043] S12, convert the collected historical data into time series data with a time interval of 1 second, and the time series data is in xlsx format;

[0044] S13: Retain the time-series data of wellhead pressure and discharge rate before sand addition, plot the construction curves corresponding to wellhead pressure and discharge rate before sand addition, and perform outlier detection and noise reduction on the retained time-series data.

[0045] The data adjacent to the outliers are replaced with the outliers, and the retained time-series data is denoised using a mean filtering method. The mean filtering method uses the following formula:

[0046]

[0047] Where, x i x represents the value of the i-th row of a column in the historical data table after noise reduction; x represents the value of a column in the fracturing data table before noise reduction.

[0048] First, historical data including time, wellhead pressure, sand concentration, bottomhole sand concentration, displacement, total fluid volume, total sand volume, stage fluid volume, and stage sand volume were collected. Then, the collected historical data was converted into time-series data with a 1-second time interval. All data in CSV and FPA formats for wellhead pressure (casing pressure), sand concentration, bottomhole sand concentration, displacement, total fluid volume, total sand volume, stage fluid volume, and stage sand volume were converted to .xlsx format with a 1-second time interval. Only historical data prior to sand addition, i.e., the time preceding the first time the sand concentration exceeded zero, was retained. Since the ball seat setting event only affects wellhead pressure data, this reduces interference from other data. Secondly, ball seat setting occurs before fracturing operations begin; subsequent operations are only performed after successful setting, further reducing interference factors. Finally, the construction curves corresponding to wellhead pressure and displacement before sand addition were plotted, as shown in the attached figure. Figure 1 As shown.

[0049] When processing retained time series data (wellhead pressure and discharge), adjacent parameters are used to replace outlier data, and mean filtering is used to reduce noise in the time series data, which can reduce the noise and outliers in the field-stored time series data.

[0050] Example 3: As an optimization of the above example, the fracturing construction curve in step S2 is the construction curve between the decrease in displacement before sand addition and the increase in displacement. The data feature points in step S2 include the wellhead pressure and displacement values ​​corresponding to the wellhead pressure before the sudden increase in wellhead pressure, the wellhead pressure and displacement values ​​corresponding to the peak value after the sudden increase in wellhead pressure, the wellhead pressure and displacement values ​​corresponding to the rapid decrease in wellhead pressure to the trough, the wellhead pressure and displacement values ​​after the wellhead pressure rises again, and the time required from the sudden increase in wellhead pressure to the rise in wellhead pressure again.

[0051] The point where the displacement decreases is taken as the starting point of the fracturing operation, and the point where the displacement increases is taken as the ending point of the fracturing operation. The construction curve between the starting point and the ending point is taken as the fracturing construction curve, as shown in the attached figure. Figure 2 As shown, by extracting the data features of the standard curve when the well is successfully set, and combining them with the bottom hole mechanism features when the well is set, the correlation between the curve features and whether the well is successfully set can be established, and threshold rules can be built to facilitate the establishment of judgment conditions.

[0052] Example 4: As an optimization of the above embodiment, step S3 includes:

[0053] S31, calculate the difference between each increase and decrease in wellhead pressure and the corresponding time span;

[0054] S32, find the common wellhead pressure response characteristics of fracturing operation curves and determine the threshold of data feature points;

[0055] S33, statistically analyze the duration of the sudden rise, rapid fall and rebound of wellhead pressure and the change of wellhead pressure, and plot the curve of the change of duration and wellhead pressure.

[0056] S34, Remove outliers from the change curve, draw a judgment curve and establish judgment conditions. The judgment conditions are: when the discharge rate is stable, the wellhead pressure must simultaneously satisfy the following conditions: the slope is greater than 0.7 within 10 seconds and the slope is less than -0.4 within the next 10 seconds; when the wellhead pressure drops rapidly to the bottom, the wellhead pressure at the bottom of the valley should be greater than the wellhead pressure corresponding to the sudden rise in wellhead pressure; when the wellhead pressure rises again, the slope of the wellhead pressure is not greater than 0.3 and not less than zero.

[0057] By calculating the difference between each increase or decrease and the corresponding time span, we can find the common wellhead pressure response characteristics of multiple fracturing operation curves, repeatedly debug and expand the time span to determine the threshold of data feature points.

[0058] The extracted fracturing operation curves were categorized into two types: successful setting and failed setting. Data feature analysis was performed on each type of fracturing operation curve, specifically analyzing the relationship between wellhead pressure and displacement during the setting process. Feature points were extracted, including the wellhead pressure value and displacement magnitude corresponding to the period before the sudden increase in wellhead pressure, and corresponding appendices. Figure 2 At point 1, the peak value reached after a sudden increase in wellhead pressure corresponds to the displacement size, and is attached... Figure 2 The two points in the image represent the lowest points reached after the wellhead pressure dropped, corresponding to the attached... Figure 2 At three points, the wellhead pressure was finally found to rise again (corresponding to the attached diagram). Figure 2 The time required for the four locations (and the corresponding wellhead pressure values) is as follows.

[0059] The duration of normal wellhead pressure setting is divided into three stages: the duration of the sudden rise in wellhead pressure, the rapid drop, and the subsequent rise, along with the corresponding changes in wellhead pressure. Histograms of duration and wellhead pressure are then obtained for each stage (see attached diagram). Figure 3 The slope variation diagram of the wellhead pressure and the wellhead pressure.

[0060] After removing the slope anomalies from the wellhead pressure slope variation graph, the attached graph is obtained. Figure 4 Then, the analysis showed that the maximum time required for the first rise in wellhead pressure was 10 seconds, and the increase in wellhead pressure was greater than 7 MPa. The maximum time required for the subsequent drop in wellhead pressure was also 10 seconds, and the drop in wellhead pressure was greater than 3 MPa. After that, the wellhead pressure would rise again in five minutes and increase by 5 MPa.

[0061] Based on the above analysis results, the following judgment criteria are established: When the discharge rate is stable, the wellhead pressure must simultaneously satisfy the following conditions: the inclination rate must be greater than 0.7 within 10 seconds, and the inclination rate must be less than -0.4 within the next 10 seconds. When the wellhead pressure rapidly drops to the bottom, the bottom value should be greater than the value when the wellhead pressure suddenly rises (see appendix). Figure 2 The wellhead pressure at point 1 is such that, in addition, with the stable injection of the discharge rate, the wellhead pressure slope is not greater than 0.3 and not less than zero.

[0062] Example 5: As an optimization of the above examples, the ball seat setting conditions include successful ball seat setting and unsuccessful ball seat setting. If the determination conditions are met, the ball seat setting is successful; otherwise, the ball seat setting fails.

[0063] If the judgment conditions are not met, that is, if the three characteristics of the above-mentioned wellhead pressure change cannot be found, the setting is considered to have failed. When the cumulative discharge has exceeded the volume of one wellbore, and the three characteristics of the above-mentioned wellhead pressure change are still not found or the wellhead pressure does not rise, the ball seat setting has failed.

[0064] The pump pressure, discharge rate, and sand concentration data at the site are input into the Python algorithm to determine the starting and ending points of the identification. The previously performed working condition interception proves that the pump start time is the identification start time. The action after the setting seal is completed is generally considered to be sand addition. Therefore, the Python algorithm uses the magnitude of the sand concentration to determine the end position of the scan.

[0065] Data is input starting from the initial moment. The input data is then calculated based on its slope to determine if it reaches the specified wellhead pressure increase value within a given timeframe, i.e., whether the corresponding slope is reached. Once the slope is confirmed to meet the standard, the descent slope is further assessed to see if it meets the criteria for the second stage. If both the first and second stages exist simultaneously, and the wellhead pressure at the end of the second stage is higher than the wellhead pressure before the start of the first stage, the existence of a subsequent third stage is verified. If all three stages exist, the wellhead is considered successfully set. A plotting function is then used to display the first stage in green, the second stage in blue, and the third stage in cyan, as shown in the attached diagram. Figure 5 As shown, continue scanning until the end position; if none of the first, second and third stages exist, or if the first and second stages exist and the wellhead pressure at the end of the second stage is lower than the wellhead pressure before the start of the first stage, and there is no significant change in wellhead pressure during the displacement increase stage, then the setting and sealing has failed.

[0066] Existing historical fracturing data is examined, and a data transmitter is used to transmit one data point per second. The results of the real-time fracturing historical data transmitted from the field are visualized and divided into two types: successful identification and failure identification. A total of 100 valid data segments are identified, of which 96 segments were successfully set and 4 segments were unsuccessful.

[0067] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for determining the operating conditions of a bridge plug fracturing ball seat, characterized in that... The steps include the following: S1. Collect historical data on fracturing operations, merge the historical datasets, and plot the operation curve. S2, extract the fracturing construction curve from the construction curve, and extract the data feature points of the fracturing construction curve; S3, establish judgment conditions based on the data feature points of the fracturing construction curve; S4, determine the ball seat setting condition according to the judgment conditions.

2. The method for determining the operating condition of the bridge plug fracturing ball seat according to claim 1, characterized in that, Step S1 includes the following steps: S11, Collect historical data of fracturing operations, including time, wellhead pressure, sand concentration, bottom hole sand concentration, discharge rate, total fluid volume, total sand volume, stage fluid volume, and stage sand volume; S12, convert the collected historical data into time series data with a time interval of 1 second, and the time series data is in xlsx format; S13: Retain the time-series data of wellhead pressure and discharge rate before sand addition, plot the construction curves corresponding to wellhead pressure and discharge rate before sand addition, and perform outlier detection and noise reduction on the retained time-series data.

3. The method for determining the working condition of the bridge plug fracturing ball seat according to claim 2, characterized in that, In step S13, the data adjacent to the outlier is replaced with the outlier, and the mean filtering method is used to denoise the retained time series data. The mean filtering method uses the following formula: Where, x i x represents the value of the i-th row of a column in the historical data table after noise reduction; x represents the value of a column in the fracturing data table before noise reduction.

4. The method for determining the operating condition of the bridge plug fracturing ball seat according to claim 1, 2, or 3, characterized in that, The fracturing operation curve in step S2 is the operation curve between the decrease in displacement before sand addition and the increase in displacement.

5. The method for determining the operating condition of the bridge plug fracturing ball seat according to claim 4, characterized in that, The data feature points in step S2 include the wellhead pressure and displacement values ​​before the wellhead pressure surges, the wellhead pressure and displacement values ​​when the wellhead pressure reaches its peak after the surge, the wellhead pressure and displacement values ​​when the wellhead pressure drops rapidly to its trough, the wellhead pressure and displacement values ​​after the wellhead pressure rises again, and the time required from the wellhead pressure surge to the wellhead pressure rising again.

6. The method for determining the operating condition of a bridge plug fracturing ball seat according to claim 1, 2, 3, or 5, characterized in that, Step S3 includes: S31, calculate the difference between each increase and decrease in wellhead pressure and the corresponding time span; S32, find the common wellhead pressure response characteristics of fracturing operation curves and determine the threshold of data feature points; S33, statistically analyze the duration of the sudden rise, rapid fall and rebound of wellhead pressure and the change of wellhead pressure, and plot the curve of the change of duration and wellhead pressure. S34, Remove outliers from the change curve, draw a judgment curve and establish judgment conditions. The judgment conditions are: when the discharge rate is stable, the wellhead pressure must simultaneously satisfy the following conditions: the slope is greater than 0.7 within 10 seconds and the slope is less than -0.4 within the next 10 seconds; when the wellhead pressure drops rapidly to the bottom, the wellhead pressure at the bottom of the valley should be greater than the wellhead pressure corresponding to the sudden rise in wellhead pressure; when the wellhead pressure rises again, the wellhead pressure slope is not greater than 0.3 and not less than zero.

7. The method for determining the operating condition of the bridge plug fracturing ball seat according to claim 4, characterized in that, Step S3 includes: S31, calculate the difference between each increase and decrease in wellhead pressure and the corresponding time span; S32, find the common wellhead pressure response characteristics of fracturing operation curves and determine the threshold of data feature points; S33, statistically analyze the duration of the sudden rise, rapid fall and rebound of wellhead pressure and the change of wellhead pressure, and plot the curve of the change of duration and wellhead pressure. S34, Remove outliers from the change curve, draw a judgment curve and establish judgment conditions. The judgment conditions are: when the discharge rate is stable, the wellhead pressure must simultaneously satisfy the following conditions: the slope is greater than 0.7 within 10 seconds and the slope is less than -0.4 within the next 10 seconds; when the wellhead pressure drops rapidly to the bottom, the wellhead pressure at the bottom of the valley should be greater than the wellhead pressure corresponding to the sudden rise in wellhead pressure; when the wellhead pressure rises again, the wellhead pressure slope is not greater than 0.3 and not less than zero.

8. The method for determining the operating condition of a bridge plug fracturing ball seat according to claim 1, 2, 3, 5, or 7, characterized in that, The ball seat setting conditions include successful ball seat setting and unsuccessful ball seat setting. If the determination conditions are met, the ball seat setting is successful; otherwise, the ball seat setting fails.

9. The method for determining the working condition of the bridge plug fracturing ball seat according to claim 4, characterized in that, The ball seat setting conditions include successful ball seat setting and unsuccessful ball seat setting. If the determination conditions are met, the ball seat setting is successful; otherwise, the ball seat setting fails.

10. The method for determining the operating condition of the bridge plug fracturing ball seat according to claim 6, characterized in that, The ball seat setting conditions include successful ball seat setting and unsuccessful ball seat setting. If the determination conditions are met, the ball seat setting is successful; otherwise, the ball seat setting fails.

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