Soluble bridge plug storage life prediction and construction failure traceability integrated quality detection method

Abstract

The invention relates to a soluble bridge plug storage life prediction and construction failure traceability integrated quality detection method, which comprises the following steps: S1, setting basic parameters and detection indexes of a soluble bridge plug, carrying out three core experiments of setting release, pressure-bearing sealing and dissolution, and constructing a complete detection data set; s2, the impurity content serves as a core parameter, the storage life of the upper portion, the middle portion and the lower portion of the bridge plug is calculated through a stability analysis model, the minimum value is taken to determine the overall life, and different storage scenes are adapted in combination with an environment correction coefficient; s3, through curve abnormal feature matching, a construction failure root is verified and positioned on site, and rectification suggestions are output; and S4, taking the average performance standard-reaching rate as target data, and realizing full-process management and control of the soluble bridge plug in the category of quality engineering. Quantitative calculation of the storage life is realized through a stability model; the use reliability of the soluble bridge plug under the working conditions of high temperature and high salinity of the shale gas horizontal well is ensured, and the engineering risk and cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of quality control of fracturing tools for shale gas horizontal wells, and more specifically, to a quality inspection method that integrates prediction of the storage life of soluble bridge plugs and tracing of construction failures. Background Technology

[0002] Shale gas, as an unconventional energy source that is "self-generated and self-storaged," relies on horizontal well fracturing technology for development. Dissolvable bridge plugs, as the core tool of fracturing, perform the crucial functions of "segment isolation and pressure sealing." After fracturing, the bridge plug dissolves spontaneously under the action of downhole fluids, eliminating the need for coiled tubing drilling, saving 200,000-300,000 RMB per well in construction costs and shortening the construction period by 3-5 days. Currently, stringent requirements are placed on the "reliability, timeliness, and adaptability" of soluble bridge plugs: they must withstand bottomhole temperatures of 90-120℃ and construction pressures of 70MPa, with a residual amount of ≤0.23kg after dissolution (to avoid wellbore blockage). Simultaneously, they must be precisely matched with hydraulic release tools (23-25t driving force) to ensure a setting success rate of ≥95%. Existing soluble bridge plug storage management is relatively crude, failing to consider the impurity growth patterns of the magnesium-aluminum alloy body and the elastic decay characteristics of the epoxy resin casing. Existing research indicates that during storage, oxygen and moisture in the air can cause intergranular corrosion in magnesium-aluminum alloys. The content of impurities (such as Fe and Cu) accumulates over time (experiments show that the impurity content increased from 0.062 to 0.077 over 24 months, exceeding the industry standard SY / T7462-2019 upper limit of 0.076), leading to a 30% decrease in metal strength and increased susceptibility to structural damage during setting. In high-temperature and high-humidity environments (temperature > 30℃, humidity > 80%), the elastic modulus of epoxy resin cartridges decreases from an initial 2.5 GPa to 1.8 GPa, resulting in reduced sealing performance and potential sealing failures during fracturing. Field statistics show that improper storage management accounts for 12.4% of bridge plug failures, with rework costs exceeding 300,000 yuan per well. Therefore, a systematic quality testing method is needed to address the inherent degradation of soluble materials and the pre-shipment testing aspects such as setting release, pressure sealing, and dissolution performance to prevent construction failures. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a quality inspection method that integrates prediction of storage life of soluble bridge plugs and traceability of construction failures. Through stability analysis and environmental correction conclusions, it can dynamically control the risk of material degradation during storage and avoid setting failure caused by overuse. Based on the correspondence between experimental curves and failure traceability, it can be implemented using existing experimental equipment. The algorithm is easy to program and integrate and can be directly applied to quality conditions.

[0004] The technical solution adopted by this invention to solve its technical problem is: to construct a quality inspection method integrating soluble bridge plug storage life prediction and construction failure tracing, comprising the following steps: S1. Set the basic parameters and detection indicators of the soluble bridge plug, carry out three core experiments: setting and releasing, pressure sealing, and dissolution, and simultaneously determine the impurity content at different storage times to construct a complete detection dataset; S2. Using impurity content as the core parameter, the storage life of the upper, middle and lower parts of the bridge plug is calculated using a stability analysis model. The minimum value is taken to determine the overall life, and the environmental correction coefficient is combined to adapt to different storage scenarios. S3. Construct a "curve-failure factor" correspondence library based on experimental curve characteristics, locate the root cause of construction failure through curve anomaly feature matching and on-site verification, and output rectification suggestions; S4. Using the average performance compliance rate as the target data, trigger life warnings during the storage stage, conduct sampling verification before construction, and review residual indicators after construction to achieve full-process control of soluble bridge plugs within the scope of quality engineering.

[0005] According to the above scheme, the method for constructing a complete detection dataset in S1 includes the following steps: S101. Record the core parameters of the soluble bridge plug: batch number, production time, specifications, rated performance, sample bridge plug composition and impurity content; select multiple batches as test samples, and extract three test sites (upper, middle and lower) from each batch to ensure sample representativeness; S102. Conduct experiments on setting seal release, pressure sealing, and dissolution; S103. Using an alloy analyzer, determine the impurity content during the storage process, record the data, and establish a "storage time - impurity content" database.

[0006] According to the above scheme, the following steps are included in the setting and release experiment in S102: Step 1: Using a setting tool, a hydrostatic testing device, and a pressure data acquisition instrument, remove the anti-rust oil from the surface of the bridge plug, connect the bridge plug coaxially with the hydraulic setting tool, connect it to the hydrostatic pipeline, and flush the pipeline with clean water to remove air. Step 2: Perform pre-pressure adjustment, then perform a seat release test, pressurize at a constant speed and record the pressure-time curve in real time; when you hear a "click" sound, stop pressurizing and maintain a stable pressure; calculate the release force using the formula (F=P×S) to verify the compatibility with the hydraulic release tool; Step 3: Repeat the experiment for each batch, take the average release pressure as the setting and release performance index of that batch, and remove unqualified samples with deviations exceeding the limit.

[0007] According to the above scheme, the pressure sealing test steps carried out in S102 include the following: Step 1: Using a high-temperature test chamber, a water pressure test device, a well shaft simulation tooling, and deionized water, weigh the materials with an electronic balance to prepare an aqueous solution. Use a mineralization meter to set the bridge plug in the well shaft simulation tooling and tighten the flanges at both ends with a torque wrench. Step 2: Conduct a room temperature pressure test, pressurize to 20MPa; pressurize to 50MPa and hold for 24 hours; if the total pressure drop after 24 hours is ≤0.6MPa, it is considered to be a qualified room temperature pressure seal. Step 3: Conduct a high-temperature pressure test. Place the tooling with the bridge plug into a high-temperature test chamber and heat it to 140℃ for 3 hours. Then, increase the pressure to 50MPa at the normal temperature test rate and hold it for 12 hours. Record the pressure every 30 minutes. If the total pressure drop after 12 hours is ≤0.8MPa, it is considered to be qualified for high-temperature pressure sealing. Step 4: Conduct pressure tests for different mineralizations. The high-temperature test chamber is heated to 90℃, and different NaCl media are injected to soak the bridge plug for 2 hours. For each medium, the pressure is maintained for 24 hours at each pressure level, and the pressure drop is recorded. Under each mineralization-pressure combination, the pressure drop after 24 hours is ≤0.7MPa, and the effective sealing time is determined to be 24 hours.

[0008] According to the above scheme, the dissolution experiment steps carried out in S102 include: Step 1: Using a constant temperature water bath, electronic balance, and nylon mesh basket, prepare a KCL solution of a certain concentration using analytical grade KCL and deionized water, and calibrate the concentration using a hydrometer; take one bridge plug from each batch, weigh the initial weight using an electronic balance, measure the outer diameter of the rubber sleeve and the height of the clamp using a vernier caliper, and record the appearance condition; Step 2: Place the bridge plug into a nylon mesh basket and completely immerse it in KCl solutions of different concentrations, monitoring the solution temperature in real time. Remove the bridge plug at 5, 7, and 11 days, rinse the surface with deionized water to remove any residual solution, blot dry with filter paper, and weigh. Weigh once every day. The bridge plug completely dissolves in 1% / 1.5% KCl solution after 10 days, in 2% KCl solution after 9.5 days, and in 2.5% KCl solution after 9 days. After the bridge plug has completely dissolved, collect the remaining cast iron locking teeth and ceramic anti-wear teeth in the nylon mesh basket. Step 3: Perform data calculations, dissolution rate: , Using dissolution time as the x-axis and bridge plug weight as the y-axis, the "complete dissolution point of the metal" and "complete dissolution point of the rubber cartridge" are marked to form a dissolution pattern at different KCl concentrations.

[0009] According to the above scheme, the stability study model equation in S2 is as follows: 1) General form of the hybrid model:

[0010] In the formula, For response value vector; For fixed effects Design matrix, ; For the model A random effect Design matrix; For unknown parameters vector; for The independent variable in vector; for The independent variable in vector; This represents the number of random effects in the model; 2) Response vector The general variance-covariance matrix is:

[0011] 3) Further decompose the variance to obtain The expression:

[0012] 4) When the batch size is a random factor, the estimated values ​​of the unknown parameters can be obtained by minimizing the negative of the restricted log-likelihood function twice. Finding the minimum value is equivalent to maximizing the restricted log-likelihood function. The function that achieves this minimization is:

[0013] In the formula, The number of observations; for The number of parameters in the stability study is 2. For the error variance component; Designing a matrix - for fixed terms, constants, and time; For having An identity matrix with rows and columns; For the first The ratio of the variance of each random term to the variance of the error; For the model Known codes for a random effect matrix; For the first The number of levels of a random effect; This represents the number of random effects in the model. for The determinant of; for transpose; For reverse ; 5) The Box-Cox transformation selects lambda that minimizes the sum of squared residuals, where It is data Transformation:

[0014] 6) Random batch model selection, consider the following three models in order: 1. Time + Batch + Batch * Time; 2. Time + Batch; 3. Time.

[0015] According to the above scheme, step S3 includes the following steps: S301. Failure Factor Classification and Feature Extraction; S302. The method for tracing the source of failure includes the following steps: Step 1: Obtain the setting release, pressure sealing, and dissolution curves of the failed bridge plug; Step 2: Compare the abnormal characteristics of the curve with the table above to initially identify 2-3 candidate failure factors; Step 3: If the candidate is "acid contamination", check the pH value of the pumped fluid and check the status of the ground process valves; if the candidate is "overdue for use", check the bridge plug production time and test the impurity content. Step 4: Identify the type of failure, key factors, and rectification recommendations.

[0016] According to the above scheme, in S301, the corresponding experimental curve characteristics are as follows:

[0017] According to the above scheme, the method for achieving full-process control of soluble bridge plugs in S4 includes: S401. Monthly inspection of bridge plug impurity content and rubber sleeve elasticity. When the storage time reaches 80% of the corrected lifespan, an alarm is triggered, and the product is stopped from being released for use. S402. Before construction of each well, three bridge plugs shall be randomly selected to conduct setting and release and pressure sealing tests. If they fail the test, the entire batch shall be discarded. S403. Post-construction review: After fracturing is completed, the weight of residues in the flowback fluid is checked to verify the rationality of the dissolution test data and construction parameters. The corresponding library of "experimental curve-failure factors" is updated, and subsequent testing standards are optimized.

[0018] According to the above scheme, in S4, the early warning triggering conditions for the storage stage are: the storage time reaches 80% of the corrected lifespan; the pre-construction verification must meet the following requirements: the setting and release pressure is 15.6±0.5MPa, the pressure drop is ≤0.6MPa / 24h; and the weight of the residue after construction is 0.19-0.23kg to be considered qualified. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to the present invention has the following beneficial effects: 1. This invention provides precise quantification of storage life, yielding a quantitative lifespan of 14.5 months through a stability analysis model. This avoids setting failure caused by exceeding the storage lifespan, and increases the success rate of bridge plug setting from 87.6% to 98.2%. 2. This invention has strong engineering adaptability. Relying on the "experimental curve-failure factor" correspondence library, the root cause of failure can be located within 2 hours, improving efficiency by 12 times and reducing the cost of single-well failure treatment by 20,000 yuan. The experimental scheme covers typical working conditions of shale gas horizontal wells at 90-120℃, 50-70MPa, and 0.5%-2.5%KCL concentration, and can be directly applied to blocks such as Changning-Weiyuan and Southern Sichuan without additional adjustment of experimental parameters. 3. The cost of this invention is controllable. It can be implemented using existing experimental equipment such as hydrostatic testers and alloy analyzers, without the need for additional equipment. The cost of quality testing for a single well is only 8,000 yuan, which is 73% lower than the cost of testing with imported tools. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of the integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to the present invention; Figure 2 This is a pressure-time curve of the soluble bridge plug setting release in this invention; Figure 3 This is the pressure-time curve of the sealing system at room temperature (25℃) according to the present invention; Figure 4 This is a high-temperature (140℃) pressure-time curve of the sealing system of this invention. Figure 5 This is a graph showing the weight-time dissolution curves of the bridge plug at different KCl concentrations at 90°C according to the present invention. Figure 6 This is a diagram showing the failed release of the bridge plug in well L206 according to the present invention; Figure 7 This is a diagram of the residue from the rubber cartridge of the present invention.

[0020] Figure 8 This is the stability regression fitting curve of the present invention.

[0021] Figure 9 This is the residual diagram of impurity content in this invention. Detailed Implementation

[0022] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0023] like Figure 1-9 As shown, the integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to the present invention includes the following steps: S1. Set the basic parameters and detection indicators for the soluble bridge plug, and conduct three core experiments: setting and release, pressure sealing, and dissolution. Simultaneously determine the impurity content at different storage times to construct a complete detection dataset. Specifically: S101, Bridge Plug Basic Information Collection: The core parameters of the soluble bridge plug (magnesium-aluminum alloy body + epoxy resin sleeve) were recorded: batch number, production time, specifications (outer diameter 103mm, inner diameter 35mm, length 424mm), rated performance (pressure resistance 70MPa, applicable temperature 90-120℃, applicable sleeve inner diameter 114-121.4mm), bridge plug composition, and impurity content. Seven batches covering different production months were selected as test samples. For each batch, 21 test sequences were extracted from three testing locations (upper, middle, and lower) to ensure sample representativeness.

[0024] S102. Conduct three core experiments: (1) Sealing and release performance test, adapted to hydraulic release tool with 23-25t driving force.

[0025] Step 1: Experimental Preparation. Tool Selection: Beck 20 hydraulic setting tool, rated output force 30t, accuracy ±0.5t, 140MPa high-temperature intelligent hydrostatic testing device with pressure control accuracy ±0.1MPa, pressure data acquisition instrument with sampling frequency 1Hz and recording interval 0.1s; Sample Pretreatment: Remove rust-preventive oil from the bridge plug surface, wipe the central tube, slip carrier, and sealing sleeve with alcohol, and check for deformation and cracks; Tooling Assembly: Connect the bridge plug and hydraulic setting tool coaxially, with a coaxiality error ≤0.5mm; Connect to the water pressure pipeline, and flush the pipeline three times with clean water with a salinity ≤500mg / L, each flushing volume 5L, to remove air and avoid pressure fluctuations.

[0026] Step 2: The experiment included: pre-pressure testing: pressurizing to 5 MPa at a rate of 0.5 MPa / min, holding the pressure for 5 minutes, observing no leakage at the pipe joints, then releasing the pressure to 0 MPa, repeating twice; setting and release test: uniformly increasing the pressure at a rate of 1 MPa / min, recording the pressure-time curve in real time; when the pressure reached 15.2 MPa, the slip carrier began to slide along the conical inclined surface, and the displacement of the tooling was observed visually; when the pressure continued to increase to 15.6 MPa, a "click" was heard. The six copper starting pins were sheared, the pressure increase was stopped, and the pressure was maintained for 10 minutes, stabilizing at 15.6MPa±0.1MPa. Data conversion: The release force was calculated using the formula (F=P×S) (P=15.6MPa, S is the piston area of ​​the setting tool, 1260mm²), resulting in (F=19.66t). This verifies the compatibility with the 23-25t hydraulic release tool (the difference is 3.34-5.34t, which meets the safety redundancy requirement).

[0027] Step 3: Conduct repeatability verification. Repeat the experiment three times for each batch. Take the average deviation of the release pressure ≤ 0.3MPa as the setting and release performance index of the batch, and remove unqualified samples with a deviation of more than 0.5MPa.

[0028] (2) Pressure-bearing sealing performance test, covering normal temperature, high temperature and different mineralization conditions. Step 1: Experimental Preparation. Tool Selection: WG220B high-temperature test chamber, temperature control range room temperature - 200℃, accuracy ±1℃, 140MPa water pressure test device, wellbore simulation fixture with inner diameter 114-121.4mm, material P110 casing, inner wall roughness Ra≤6.3μm; Media Preparation: Clean water medium: deionized water, conductivity ≤10μS / cm, mineralization ≤500mg / L; Mineralization medium: Weigh NaCl with an electronic balance with an accuracy of 0.01g, and prepare aqueous solutions of 10000mg / L, 30000mg / L, and 50000mg / L respectively. Calibrate the concentration using a mineralization meter with an accuracy of ±100mg / L; Sample Installation: Set the bridge plug inside the wellbore simulation fixture, and tighten the flanges at both ends with a torque wrench with an accuracy of ±5N·m, ensuring a tight fit between the rubber sleeve and the inner wall of the fixture, with an initial contact pressure ≥2MPa.

[0029] Step 2: Conduct ambient temperature pressure test at 25℃±2℃: Pressure increase stage: Increase the pressure to 20MPa at a rate of 1MPa / min, hold the pressure for 5min to eliminate the influence of tooling elastic deformation; continue to increase the pressure to 50MPa at a rate of 2MPa / min to 70% of the rated pressure, hold the pressure for 24h; Data monitoring: Record the pressure value every 1h and calculate the pressure drop; if the pressure drop exceeds 0.1MPa / h in a certain period, shorten the recording interval to 10min and locate the leak point; Pass judgment: Total pressure drop ≤ 0.6MPa in 24h. If the pressure drop of the batch used in well L203 is measured to be 0.4MPa, it is considered to be qualified for ambient temperature pressure sealing.

[0030] Step 3: High-temperature pressure test at 140℃±1℃: Heating stage: Place the tooling with the bridge plug into the high-temperature test chamber and heat it to 140℃ at a rate of 5℃ / min, and hold it at that temperature for 3 hours (ensure that the overall temperature of the bridge plug is uniform and the temperature difference is ≤2℃); Pressure increase and holding: Increase the pressure to 50MPa at the same rate as the room temperature test, hold the pressure for 12 hours, and record the pressure every 30 minutes; Passing judgment: The total pressure drop in 12 hours is ≤0.8MPa (the pressure drop measured in the experiment is 0.4MPa), which is considered as passing the high-temperature pressure sealing test.

[0031] Step 4: Conduct pressure tests at different mineralization levels (90℃±1℃): Operating conditions: The high-temperature test chamber is set to 90℃, the average bottom-hole temperature of the shale gas well in southern Sichuan. NaCl media of 10000mg / L, 30000mg / L, and 50000mg / L are injected respectively, and the bridge plug is soaked for 2 hours to simulate the downhole soaking state; Pressure test: For each medium, the pressure is increased to 100% of the rated pressure of 50MPa, 60MPa, and 70MPa in sequence, and the pressure is maintained for 24 hours at each pressure level, and the pressure drop is recorded; Results: Under each mineralization-pressure combination, the pressure drop after 24 hours is ≤0.7MPa, and the effective sealing time is determined to be 24 hours, which meets the requirements of multi-stage fracturing construction.

[0032] (3) Dissolution performance test (simulating the KCl solution environment at 90℃ downhole) Step 1: Prepare for the experiment. Tool Selection: 90℃ constant temperature water bath with temperature control accuracy ±0.5℃ and volume 50L; electronic balance with accuracy 0.01g and range 0-10kg; nylon mesh basket with aperture 0.5mm and dimensions 200mm×100mm×100mm, used to hold bridge plugs; Media Preparation: Prepare KCL solutions with concentrations of 0.5%, 1%, 1.5%, 2%, and 2.5% using analytical grade KCL (purity ≥99.5%) and deionized water. The KCL mass per 1000mL of solution is 5g, 10g, 15g, 20g, and 25g respectively. The concentration is calibrated using a hydrometer with an accuracy of ±0.001g / cm³; Sample Weighing: Take one bridge plug from each batch and weigh it using an electronic balance (initial weight recorded as m_0, average 7.49kg). Measure the outer diameter of the rubber sleeve and the height of the slips using vernier calipers with an accuracy of ±0.02mm, and record the appearance, elasticity of the rubber sleeve, and the luster of the metal surface.

[0033] Step 2: The experimental procedure included immersion testing: the bridge plug was placed in a nylon mesh basket and completely immersed in KCl solutions of different concentrations, with the liquid level 100 mm above the bridge plug. A constant temperature water bath was maintained at 90°C, and the solution temperature was monitored in real time. Stage weighing: -0.5% KCl solution: the bridge plug was removed at 5, 7, and 11 days, and the surface residual solution was rinsed with deionized water (rinsing time 30 seconds). After the water was absorbed with filter paper, the weight was recorded as (m_t). The dissolution state was observed: at 5 days, the metal body was pasty with no obvious structure; at 7 days, the metal was completely dissolved, leaving only the rubber tube; at 11 days… When the rubber plug completely dissolves, only cast iron / ceramic residue remains; 1%-2.5% KCl solution: weigh once every 1 day and record the dissolution time: 1% / 1.5% KCl solution completely dissolves in 10 days, 2% KCl solution completely dissolves in 9.5 days, and 2.5% KCl solution completely dissolves in 9 days; Residue treatment: after the bridge plug is completely dissolved, collect the remaining cast iron locking teeth and ceramic anti-wear teeth in the nylon mesh basket, wash 3 times with 95% pure alcohol, dry in a 105℃ oven for 2 hours, cool to room temperature and weigh to obtain a residue weight of 0.19-0.23 kg.

[0034] Step 3: The data calculation process includes dissolution rate: , The dissolution time is given, for example, in a 2.5% KCl solution (v=(7.49-0.19) / 9=0.81kg / d); a dissolution curve is plotted: with time as the x-axis and bridge plug weight as the y-axis, the "complete dissolution point of the metal" and "complete dissolution point of the rubber cartridge" are marked to form a dissolution pattern at different KCl concentrations.

[0035] S103. Stability testing procedure: Using a Thermo Scientific Niton xl2 alloy analyzer with a testing accuracy of ±0.01%, the impurity content of 21 operating sequences was determined after storage for 0, 3, 6, 9, 12, 18, and 24 months. The tested elements included Fe, Cu, and Ni. The data were recorded and a "storage time - impurity content" database was established.

[0036] S2. Using impurity content as the core parameter, the storage life of the upper, middle and lower parts of the bridge plug is calculated using a stability analysis model. The minimum value is taken to determine the overall life, and the environmental correction coefficient is combined to adapt to different storage scenarios.

[0037] Stability study models are essentially mathematical regression analyses. Their function is to analyze the stability of a product's quantitative characteristic over a period of time to comprehensively determine the product's shelf life. The equation is as follows: 1) General form of the hybrid model:

[0038] In the formula: For response value vector; For fixed effects Design matrix, ; For the model A random effect Design matrix; For unknown parameters vector; for The independent variable in vector; for The independent variable in vector; This represents the number of random effects in the model.

[0039] 2) Response vector The general variance-covariance matrix is:

[0040] 3) Further decompose the variance to obtain The expression:

[0041] 4) When the batch size is a random factor, the estimated values ​​of the unknown parameters can be obtained by minimizing the negative of the restricted log-likelihood function twice. Finding the minimum value is equivalent to maximizing the restricted log-likelihood function. The function that achieves this minimization is:

[0042] In the formula: The number of observations; for The number of parameters in the stability study is 2. For the error variance component; Designing a matrix - for fixed terms, constants, and time; For having An identity matrix with rows and columns; For the first The ratio of the variance of each random term to the variance of the error; For the model Known codes for a random effect matrix; For the first The number of levels of a random effect; This represents the number of random effects in the model. for The determinant of; for transpose; For reverse .

[0043] 5) The Box-Cox transformation selects lambda that minimizes the sum of squared residuals, where It is data Transformation:

[0044] 6) Randomized batch model selection: Model selection determines whether shelf life depends on the batch and whether the time effect depends on the batch. Consider the following three models in order: 1. Time + Batch + Batch * Time: The slope and intercept of each batch are unequal; 2. Time + Batch: The slopes of each batch are equal, but the intercepts are unequal; 3. Time + Batch: The slopes and intercepts of both batches are equal. If the "batch * time" interaction term is significant, the analysis will fit the first model. If the interaction term is not significant, but the batch term is significant in the second model, the analysis will fit the second model. Otherwise, the analysis will fit the third model.

[0045] S3. Construct a "curve-failure factor" correspondence library based on experimental curve characteristics. Locate the root cause of construction failures through curve anomaly feature matching and on-site verification, and output rectification suggestions. Specifically: S301. Failure Factor Classification and Feature Extraction Based on the successful case of well L203 and the failed case of well L206, we identified 12 failure factors in three main categories and extracted the corresponding experimental curve characteristics:

[0046] S302. The method for tracing the source of failure includes the following steps: Step 1: Curve acquisition to obtain the setting release, pressure sealing, and dissolution curves of the failed bridge plug (if the failure occurred during construction, collect the real-time pressure curve; if the failure occurred after dissolution, collect the weight of the residue and the dissolution time). Step 2: Feature matching. Compare the abnormal features of the curve with the table above to initially identify 2-3 candidate failure factors (e.g., dissolution time 8d → candidate factors "acid mixing" and "excessive cosolvent"). Step 3: On-site verification. If the candidate is "acid contamination": test the pH value of the pumped fluid (confirmation if <7) and check the status of the ground process valves for internal leakage. If the candidate is "overdue for use": check if the bridge plug has been manufactured for more than 14.5 months and test the impurity content (confirmation if >0.076). Step 4: Output the report, clearly identifying the failure type, key factors, and rectification suggestions. For example, if acid is mixed in, the pump fluid should be replaced with an acid-free pump; if the pump has exceeded its service life, the remaining bridge plugs should be discarded.

[0047] S4. Using the average performance compliance rate as the target data, trigger life warnings during the storage stage, conduct sampling verification before construction, and review residual indicators after construction to achieve full-process control of soluble bridge plugs within the scope of quality engineering.

[0048] S41. Implement storage phase control, and test the impurity content of the bridge plug and the elasticity of the rubber sleeve every month. When the storage time reaches 80% of the corrected life (e.g., 11.6 months under normal temperature and dry conditions), trigger an alarm and stop the use of the product. S42. Conduct pre-construction verification. Before construction of each well, randomly select three bridge plugs to conduct setting and release (release pressure 15.6±0.5MPa) and pressure sealing (pressure drop ≤0.6MPa / 24h) tests. If they fail, the entire batch will be discarded. S43. After the fracturing operation is completed, check the weight of the residue in the flowback fluid (0.19-0.23kg is acceptable) to verify the rationality of the dissolution test data and construction parameters, update the corresponding library of "experimental curve-failure factors", and optimize the subsequent testing standards.

[0049] Example A quality inspection method integrating storage life prediction and construction failure tracing for soluble bridge plugs includes the following steps: S1. Basic Parameters and Experimental Data Acquisition Bridge plug basic parameters: outer diameter 103mm, inner diameter 35mm, length 424mm, rated pressure 70MPa, applicable temperature 90-120℃; setting and release test: release pressure 15.6MPa (equivalent to 19.66t), pressure fluctuation ±0.1MPa, matched with 23-25t hydraulic tools; pressure bearing and sealing test: pressure drop of 0.4MPa after holding at 50MPa for 24h at room temperature, pressure drop of 0.3MPa after holding at 50MPa for 12h at 140℃, pressure drop of 0.6MPa after holding at 70MPa for 24h at 50000mg / L mineralization; dissolution test: completely dissolved in 2% KCL solution at 90℃ for 10d, with a residue of 0.21kg; stability test: initial impurity content of each part in 7 batches (202301-202307): upper part 0.062, middle part 0.069, lower part 0.071.

[0050] S2, Storage Life Prediction Based on actual testing, this type of soluble bridge plug began small-scale mass production after successful trials in 2019. To date, it has been in field use for 6 years. Following the original 2-year stability testing plan established in December 2019, one soluble bridge plug from each of seven batches spanning two years was randomly selected. The content of metallic impurities in the upper, middle, and lower parts of the sample bridge plugs was tested using Thermo Scientific Niton xl2 alloy. The test results are shown in Table 2.

[0051] Table 2 Stability Study Worksheet

[0052] Using Minitab software, enter the test results in Table 2 and input the conditional data sequentially. Run the stability study model in the regression analysis. The results are shown in Table 3. Figure 8 , Figure 9 .

[0053] Table 3. Analysis of Impurity Interactions

[0054] The calculation yields: (1) In the source item P The values ​​were all less than the significance level of 0.25, indicating that they were all statistically significant. However, the slopes in the regression equations for each batch were different. The slope of the middle batch was the largest, increasing by 0.000393 percentage points each month. (2) Regarding the estimation of the stable period, from the perspective of impurity content, the upper batch was 42.734 months, the middle batch was 16.078 months, and the lower batch was 14.5 months. Because the bridge plug work is affected by the downhole environment, the minimum value of 14.5 months was taken as the overall shelf life. That is, it needs to be used before March 2025.

[0055] S3. Case study on construction failure tracing, simulating a similar failure to well L206. S301. Failure Phenomenon: In February 2025, a well with a horizontal section length of 1500m, a well temperature of 95℃, and a salinity of 30000mg / L experienced a failure to set the bridge plug after 3 hours of pumping during the sixth stage of fracturing. Upon retrieval of the tool string, it was found that the bridge plug had no upper or lower slips, the outer diameter of the anti-collision ring had decreased from 98mm to 84mm, the outer diameter of the spacer ring was 87.73mm, and the outer diameter of the lower cone ring was 88mm.

[0056] S302, Traceability Process Step 1: The curve acquisition process was as follows: during construction, the real-time setting and release curve showed no obvious pressure peak, and the dissolution pre-experiment (90℃, 2% KCL) showed a dissolution time of 8 days (normal 10 days). Step 2: Feature matching: The curve features correspond to "tool string deployment time exceeds 7 hours" and "acid mixing"; Step 3: On-site verification: - Check the tool string lowering time: 7 hours and 9 minutes from entering the well to the predetermined position (exceeding 7 hours); - Detect the pumped fluid: pH value 5.2 (acidic), acid concentration 8% (due to internal leakage in the junction valve between the acid tank and the solubilizer tank). Step 4: Conclusion: The root cause of the failure was "tool string dropping timeout + acid mixed in with pump fluid", which caused the bridge plug to dissolve prematurely and fail to set. Step 5: Corrective measures: Replace the internal leakage valve and use an acid-free pump to deliver fluid; the subsequent construction control tool string lowering time should be ≤5h, and temperature-pressure sensors should be installed on the tool string for real-time monitoring.

[0057] S4, Closed-loop management Storage phase: In January 2025 (12 months of storage), the impurity content was tested: 0.065 in the upper part, 0.072 in the middle part, and 0.074 in the lower part (all < 0.076), and continued use was allowed; in March 2025 (14.5 months), the batch was discontinued; before construction: after rectification in February 2025, three bridge plugs were sampled for testing: the setting release pressure was 15.5 MPa, and the pressure drop was 0.5 MPa, which was qualified; after construction: the residual backflow liquid was 0.20 kg (qualified), and the corresponding database was updated: when the tool string was placed for 7 hours and the acid concentration was 8%, the dissolution time was shortened by 2 days, providing data support for similar working conditions in the future.

[0058] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A quality inspection method integrating soluble bridge plug storage life prediction and construction failure tracing, characterized in that, Includes the following steps: S1. Set the basic parameters and detection indicators of the soluble bridge plug, carry out three core experiments: setting and releasing, pressure sealing, and dissolution, and simultaneously determine the impurity content at different storage times to construct a complete detection dataset; S2. Using impurity content as the core parameter, the storage life of the upper, middle and lower parts of the bridge plug is calculated using a stability analysis model. The minimum value is taken to determine the overall life, and the environmental correction coefficient is combined to adapt to different storage scenarios. S3. Construct a "curve-failure factor" correspondence library based on experimental curve characteristics, locate the root cause of construction failure through curve anomaly feature matching and on-site verification, and output rectification suggestions; S4. Using the average performance compliance rate as the target data, trigger life warnings during the storage stage, conduct sampling verification before construction, and review residual indicators after construction to achieve full-process control of soluble bridge plugs within the scope of quality engineering.

2. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 1, characterized in that, In step S1, the method for constructing the complete detection dataset includes the following steps: S101. Record the core parameters of the soluble bridge plug: batch number, production time, specifications, rated performance, sample bridge plug composition and impurity content; select multiple batches as test samples, and extract three test sites (upper, middle and lower) from each batch to ensure sample representativeness; S102. Conduct experiments on setting seal release, pressure sealing, and dissolution; S103. Using an alloy analyzer, determine the impurity content during storage, record the data, and establish a "storage time - impurity content" database.

3. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 2, characterized in that, The following steps are included in the setting and release experiment conducted in S102: Step 1: Using a setting tool, a hydrostatic testing device, and a pressure data acquisition instrument, remove the anti-rust oil from the surface of the bridge plug, connect the bridge plug coaxially with the hydraulic setting tool, connect it to the hydrostatic pipeline, and flush the pipeline with clean water to remove air. Step 2: Perform pre-pressure adjustment, then perform setting and release test, pressurize at a constant speed, and record the pressure-time curve in real time; Upon hearing a "click" sound, stop increasing the pressure and maintain a stable pressure; calculate the release force using the formula (F=P×S) to verify the compatibility with the hydraulic release tool; Step 3: Repeat the experiment for each batch, take the average release pressure as the setting and release performance index of that batch, and remove unqualified samples with deviations exceeding the limit.

4. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 2, characterized in that, The pressure sealing test conducted in step S102 includes the following steps: Step 1: Using a high-temperature test chamber, a water pressure test device, a well shaft simulation tooling, and deionized water, weigh the materials with an electronic balance to prepare an aqueous solution. Use a mineralization meter to set the bridge plug in the well shaft simulation tooling and tighten the flanges at both ends with a torque wrench. Step 2: Conduct a room temperature pressure test, pressurize to 20MPa; pressurize to 50MPa and hold for 24 hours; if the total pressure drop after 24 hours is ≤0.6MPa, the room temperature pressure seal is considered qualified. Step 3: Conduct a high-temperature pressure test. Place the tooling with the bridge plug into a high-temperature test chamber and heat it to 140℃ for 3 hours. Then, increase the pressure to 50MPa at the normal temperature test rate and hold it for 12 hours. Record the pressure every 30 minutes. If the total pressure drop after 12 hours is ≤0.8MPa, it is considered to be qualified for high-temperature pressure sealing. Step 4: Conduct pressure tests for different mineralizations. The high-temperature test chamber is heated to 90℃, and different NaCl media are injected to soak the bridge plug for 2 hours. For each medium, the pressure is maintained for 24 hours at each pressure level, and the pressure drop is recorded. Under each mineralization-pressure combination, the pressure drop after 24 hours is ≤0.7MPa, and the effective sealing time is determined to be 24 hours.

5. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 2, characterized in that, The dissolution experiment performed in step S102 includes: Step 1: Using a constant temperature water bath, electronic balance, and nylon mesh basket, prepare a KCL solution of a certain concentration using analytical grade KCL and deionized water, and calibrate the concentration using a hydrometer; take one bridge plug from each batch, weigh the initial weight using an electronic balance, measure the outer diameter of the rubber sleeve and the height of the clamp using a vernier caliper, and record the appearance condition; Step 2: Place the bridge plug into a nylon mesh basket and completely immerse it in KCl solutions of different concentrations, monitoring the solution temperature in real time. Remove the bridge plug at 5, 7, and 11 days, rinse the surface with deionized water to remove any residual solution, blot dry with filter paper, and weigh. Weigh once every day. The bridge plug completely dissolves in 1% / 1.5% KCl solution after 10 days, in 2% KCl solution after 9.5 days, and in 2.5% KCl solution after 9 days. After the bridge plug has completely dissolved, collect the remaining cast iron locking teeth and ceramic anti-wear teeth in the nylon mesh basket. Step 3: Perform data calculations, dissolution rate: , Using dissolution time as the x-axis and bridge plug weight as the y-axis, the "complete dissolution point of the metal" and "complete dissolution point of the rubber cartridge" are marked to form a dissolution pattern at different KCl concentrations.

6. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 1, characterized in that, In S2, the stability study model equation is as follows: 1) General form of the hybrid model: In the formula, For response value vector; For fixed effects Design matrix, ; For the model A random effect Design matrix; For unknown parameters vector; for The independent variable in vector; for The independent variable in vector; This represents the number of random effects in the model; 2) Response vector The general variance-covariance matrix is: 3) Further decompose the variance to obtain The expression: 4) When the batch size is a random factor, the estimated value of the unknown parameter can be obtained by minimizing the negative of the restricted log-likelihood function twice; finding the minimum value is equivalent to maximizing the restricted log-likelihood function; the function that achieves minimization is: In the formula, The number of observations; for The number of parameters in the stability study is 2. For the error variance component; Designing a matrix - for fixed terms, constants, and time; For having An identity matrix with rows and columns; For the first The ratio of the variance of each random term to the variance of the error; For the model Known codes for a random effect matrix; For the first The number of levels of a random effect; This represents the number of random effects in the model; for The determinant of; for Transpose of; For reverse ; 5) The Box-Cox transformation selects lambda that minimizes the sum of squared residuals, where It is data Transformation: 6) Random batch model selection, consider the following three models in order:

1. Time + Batch + Batch * Time; 2. Time + Batch; 3. Time.

7. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 1, characterized in that, S3 includes the following steps: S301. Failure Factor Classification and Feature Extraction; S302. The method for tracing the source of failure includes the following steps: Step 1: Obtain the setting release, pressure sealing, and dissolution curves of the failed bridge plug; Step 2: Compare the abnormal characteristics of the curve with the table above to initially identify 2-3 candidate failure factors; Step 3: If the candidate is "acid contamination", check the pH value of the pumped fluid and check the status of the ground process valves; if the candidate is "overdue for use", check the bridge plug production time and test the impurity content. Step 4: Identify the type of failure, key factors, and rectification recommendations.

8. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 1, characterized in that, In S301, the corresponding experimental curve characteristics are as follows:

9. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 1, characterized in that, In step S4, the method for achieving full-process control of soluble bridge plugs includes: S401. Monthly inspection of bridge plug impurity content and rubber sleeve elasticity. When the storage time reaches 80% of the corrected lifespan, an alarm is triggered, and the product is stopped from being released for use. S402. Before construction of each well, three bridge plugs shall be randomly selected to conduct setting and release and pressure sealing tests. If they fail the test, the entire batch shall be discarded. S403. Post-construction review: After fracturing is completed, the weight of residues in the flowback fluid is checked to verify the rationality of the dissolution test data and construction parameters. The corresponding library of "experimental curve-failure factors" is updated, and subsequent testing standards are optimized.

10. The integrated quality inspection method for predicting the storage life of soluble bridge plugs and tracing construction failures according to claim 1, characterized in that, In S4, the early warning trigger conditions for the storage stage are: the storage time reaches 80% of the corrected lifespan; the pre-construction verification must meet the following requirements: the setting and release pressure is 15.6±0.5MPa, the pressure drop is ≤0.6MPa / 24h; and the weight of the residue after construction is 0.19-0.23kg to be considered qualified.

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