A method for testing a bridge plug under simulated reservoir conditions based on construction characteristics

Abstract

The application provides a bridge plug testing method based on construction characteristics under simulated reservoir conditions. The method is based on the collection and arrangement of development well geological data and different stage construction characteristics, optimally selects a bridge plug suitable for the development well, simulates the reservoir temperature and pressure environment and fluid characteristics of the development well in a laboratory environment, and performs systematic performance testing on the selected bridge plug before being lowered into the well. The real performance of the bridge plug is evaluated by comparing the test results at different stages with theoretical technical parameters. The method is suitable for both land and offshore development wells, and is suitable for soluble bridge plugs and composite bridge plugs. The method not only completely simulates the reservoir temperature and pressure environment of the development well, but also considers important characteristics such as reservoir fluid salinity and pH value. Furthermore, the method is targeted for indoor simulation testing through different stage construction characteristics, so that the method is more systematic and scientific. The test results have important guiding significance for bridge plug design and development, field construction optimization and reduction of operation risks.

Description

Technical Field

[0001] This invention belongs to the field of oil well tool testing technology, specifically relating to a bridge plug testing method based on simulated reservoir conditions and construction characteristics. Background Technology

[0002] With the development of petroleum technology, staged fracturing has become an important development measure for unconventional oil and gas reservoirs. In the staged fracturing process, bridge plugs need to be run into predetermined positions in the oil and gas well to isolate other layers in the well, thereby achieving the purpose of staged fracturing and reservoir stimulation. As a key tool in staged fracturing, the performance of bridge plugs directly affects the downhole sealing effect and the quality of fracturing operations. Therefore, conducting real performance tests before running bridge plugs into the well is crucial for reducing construction risks and ensuring construction quality.

[0003] In existing technologies, there are two main methods for testing bridge plugs. One method involves using a specific testing device to test the performance of local components of the bridge plug, including tests on thread release shear value, rubber barrel sealing performance, bridge plug pressure bearing capacity, slip pressure bearing capacity, and material dissolution performance. However, since the test object is an incomplete bridge plug, the test results cannot effectively reflect the true performance of a complete bridge plug. The other method involves simulating actual reservoir temperature and pressure conditions in the laboratory to test the performance of complete bridge plugs. The test content mainly focuses on key performance indicators such as bridge plug release and setting, ball drop pressure bearing capacity, and material dissolution. However, the overall simulated reservoir conditions are relatively simple, and the test fluid is mainly fresh water or clean water, ignoring important characteristics such as reservoir fluid salinity and pH value. Furthermore, it does not fully consider the construction characteristics of different stages of staged fracturing and their impact on reservoir temperature and pressure conditions. In particular, in recent years, oil and gas exploration and development in both offshore and onshore environments has gradually expanded to deeper and ultra-deep layers, and the number of high-temperature and high-pressure development wells has increased significantly. The reservoir environment of such oil and gas wells is more complex, and staged fracturing construction has a greater impact on development results.

[0004] Therefore, it is urgent to propose a bridge plug testing method based on construction characteristics under simulated reservoir conditions. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies, such as the relatively simple indoor simulated reservoir conditions, the lack of sufficient consideration of the construction characteristics of different stages of segmented fracturing and their impact on reservoir temperature and pressure conditions, and the fact that the test fluid is mostly clean water or fresh water, neglecting important characteristics such as reservoir fluid salinity and pH value, resulting in a lack of scientific guidance in the test results. This invention provides a bridge plug testing method based on construction characteristics under simulated reservoir conditions.

[0006] To achieve the above objectives, the technical solution provided by this invention is: a bridge plug testing method based on construction characteristics under simulated reservoir conditions, comprising the following steps:

[0007] Step 1: Determine the indoor simulation test conditions and procedures, and screen candidate bridge plugs for testing, including the following sub-steps:

[0008] Step 1.1: Collect geological data of the development well for use in laboratory simulation of the initial conditions of the reservoir environment; the data includes the formation depth of the development well, the initial temperature of the wellbore, the initial pressure of the wellbore, the salinity of the reservoir fluid, and the acidity and alkalinity of the fluid;

[0009] Step 1.2: Determine the mine construction process and the construction parameters corresponding to different construction stages based on the geological data in Step 1.1, for indoor simulation of the reservoir environment at different construction stages; the construction parameters include pumping discharge rate, well run-in time, wellbore temperature and pressure conditions at different stages, and fracturing process parameters.

[0010] Step 1.3: Based on the geological data of the development well in Step 1.1 and the construction conditions and procedures in Step 1.2, a preliminary screening of the type, size, structure, and material of the bridge plugs required for the development well is conducted. The preliminary screening determines that the bridge plug types that meet the requirements are A, B, C, etc., and the quantity of each type of bridge plug is n. Before testing, the theoretical parameters of the different types of candidate bridge plugs are determined.

[0011] Step 2: Under simulated reservoir conditions based on construction characteristics, randomly test one type of n (n ≥ 3) candidate bridge plugs. When three consecutive bridge plugs meet the test conditions, it indicates that this type of bridge plug meets the requirements, and proceed to Step 3; when two bridge plugs fail to meet the test conditions, return to Step 1 and select another type of bridge plug. The test includes the following sub-steps:

[0012] Step 2.1: Bridge plug appearance and dimensions test;

[0013] Step 2.2: Simulated bridge plug downhole pumping test;

[0014] Step 2.3: Simulate bridge plug release and sealing test;

[0015] Step 2.4: Simulate the sealing pressure test before bridge plug fracturing;

[0016] Step 2.5: Simulated bridge plug fracturing seal pressure test;

[0017] Step 2.6: Simulate the dissolution performance test or drilling performance test after bridge plug fracturing. The dissolution performance test is for soluble bridge plugs, and the drilling performance test is for composite bridge plugs.

[0018] Step 3: Conduct an overall performance evaluation of all candidate bridge plugs. If they meet the evaluation criteria, they can be deployed to the well. If they do not meet the evaluation criteria, return to Step 1 and select a new candidate bridge plug type.

[0019] Furthermore, in step 2.1, the appearance parameters of the candidate bridge plug are measured, including the maximum outer diameter D1, the minimum inner diameter d1, the overall length H1, and the overall weight G1. The measured data are compared with the theoretical parameters of the candidate bridge plug: maximum outer diameter D0, minimum inner diameter d0, overall length H0, and overall weight G0. If the difference in the corresponding parameter dimensions is ≤0.5mm and the difference in weight is ≤500g, it proves that the appearance dimensions of the candidate bridge plug meet the test requirements, and the next step, step 2.2, is performed; otherwise, the test of the bridge plug is stopped, and the next bridge plug is tested.

[0020] Furthermore, in step 2.2, the indoor simulated well is filled with test fluid, and the test fluid is heated to a specified temperature T1. The bridge plug is then placed into the simulated well; the pressure is increased to a specified pressure P1, and after the pressure stabilizes, the bridge plug is immersed in the simulated well for a specified time t1 while maintaining the temperature and pressure. After immersion, the bridge plug is removed; the surface condition of the bridge plug is observed, and the appearance parameters of the bridge plug, namely the maximum outer diameter D2, the minimum inner diameter d2, the overall length H2, and the overall weight G2, are measured again and compared with the corresponding theoretical parameters of the bridge plug. If the difference in the corresponding parameter dimensions is ≤0.5mm and the difference in weight is ≤500g, then the next step, step 2.3, can be performed; otherwise, the test of the bridge plug is stopped, and the next bridge plug test is performed.

[0021] Furthermore, in step 2.3, under normal temperature and pressure conditions on the ground, the bridge plug and the corresponding bridge plug setting tool are assembled and set inside the test sleeve short section. Then, pressure testing or gunpowder setting is performed, and the test drop value Q1 is recorded. By comparing with the theoretical drop value Q0 of the bridge plug, and through ground pressure testing, it is determined whether the bridge plug is set well and whether the rubber barrel is opened well: the error between the measured drop value and the theoretical drop value of the bridge plug should not exceed 2 tons, which proves that the drop value is normal; if the error exceeds 2 tons, it indicates that the drop value is abnormal; if the drop value of the candidate bridge plug is normal and the ground pressure testing is normal, it proves that the candidate bridge plug is set well and the rubber barrel is opened well, and the next step 2.4 test can be carried out; otherwise, the test of the bridge plug is stopped and the next bridge plug test is carried out.

[0022] Furthermore, in step 2.4, the set bridge plug is sealed by dropping a ball or using a plug, and then lowered back into a simulated well containing test fluid. The bridge plug is heated and pressurized to a specified temperature and pressure, and then soaked in heat and pressure. The pressure-time change curve is recorded during the soaking period. The sealing and pressure-bearing performance of the bridge plug before fracturing is judged by this change curve, where the specified temperature is T2, the specified pressure is P2, and the soaking time is t2. If the test pressure value of the candidate bridge plug should always be based on the designed pressure threshold and fluctuate within 5% above or below the benchmark during the heat and pressure holding period, and the soaking time is also met, then the next step, step 2.5, is performed; otherwise, the test of that bridge plug is stopped, and the next bridge plug is tested.

[0023] Furthermore, in step 2.5, the bridge plug from step 2.4 is further heated and pressurized to a specified temperature and pressure, followed by heat preservation and pressure holding immersion. The pressure-time change curve is recorded during the immersion period. This curve is used to determine the sealing and pressure-bearing performance of the bridge plug in fracturing. The specified temperature is T3, the specified pressure is P3, and the immersion time is t3. If, during the heat preservation and pressure holding period, the test pressure value of the candidate bridge plug is always based on the design pressure value and fluctuates within 5% above or below the design pressure value, and the test time is also met, then the next step, step 2.6, is performed. Otherwise, the test of that bridge plug is stopped, and the next bridge plug is tested.

[0024] Furthermore, step 2.6 includes the following:

[0025] (1) Post-fracturing dissolution performance test of soluble bridge plugs:

[0026] Under normal temperature and pressure conditions on the ground, the bridge plug after the test in step 2.5 was further immersed in the test fluid solution at a temperature of T1 to carry out the dissolution performance test. The remaining products were analyzed at every time interval t, and the dissolution time of the bridge plug, the mass of the residue, the maximum size of the residue monomer, the proportion of the residue and other data were recorded to evaluate the dissolution performance.

[0027] (2) Post-fracturing drilling performance test of composite bridge plugs:

[0028] Under normal temperature and pressure conditions on the ground, the bridge plug tested in step 2.5 was drilled and ground on a machine tool. The drilling and grinding time, the weight of drill chips and residues were recorded to evaluate the drilling and grinding performance.

[0029] Furthermore, the test fluid in step 2.2 is a real well fluid sample from the development well or a prepared solution with the same percentage of chloride mineralization and pH.

[0030] Furthermore, the relationship between the specified temperature and the specified pressure is: T2>T1, P2>P1, T3=T2, P3>P2.

[0031] Furthermore, the specified pressures P1, P2, and P3 can fluctuate by up to 5% during actual testing. If the fluctuation exceeds the upper limit, an automatic pressure relief operation is required; if the fluctuation is below the lower limit, an automatic pressure replenishment operation is required.

[0032] Beneficial effects

[0033] The advantages of this invention are: This invention discloses a new method for bridge plug testing under simulated reservoir conditions based on construction characteristics. This testing method, based on the collection and organization of geological data and construction characteristics at different stages of development wells, selects bridge plugs suitable for development wells and simulates the temperature, pressure, and fluid characteristics of the development well reservoir in an indoor environment. It then conducts systematic performance tests on candidate bridge plugs before they are run into the well. The entire testing process includes, in sequence, bridge plug appearance and size testing, simulated bridge plug run-in pumping testing, simulated bridge plug release and setting testing, simulated bridge plug pre-fracturing sealing pressure testing, simulated bridge plug during fracturing sealing pressure testing, and simulated bridge plug post-fracturing dissolution / drillability testing. This method enables the testing and overall performance evaluation of bridge plugs. By comparing test results at different stages with theoretical technical parameters, the actual performance of the bridge plugs can be assessed. Compared with existing testing methods, this method is applicable to both onshore and offshore development wells, and to both soluble and composite bridge plugs. It not only fully simulates the temperature and pressure environment of the development well reservoir, but also considers important characteristics such as reservoir fluid salinity and pH. Furthermore, it conducts targeted indoor simulation tests based on the construction characteristics at different stages, making the testing method more systematic and scientific. The test results have important guiding significance for bridge plug design and development, on-site construction optimization, and reduction of operational risks. Attached Figure Description

[0034] Figure 1 A flowchart illustrating a bridge plug testing method under simulated reservoir conditions based on construction characteristics.

[0035] Figure 2 Flowchart for bridge plug appearance dimension testing

[0036] Figure 3 Flowchart for simulating bridge plug downhole pumping test

[0037] Figure 4 Flowchart for simulating bridge plug drop-off and setting test

[0038] Figure 5 A flowchart simulating the pressure-bearing test of the seal before bridge plug fracturing.

[0039] Figure 6 A flowchart simulating the pressure-bearing test of a bridge plug during fracturing.

[0040] Figure 7 Flowchart for simulating the dissolution / drilling performance test after bridge plug fracturing

[0041] Table 1 shows the theoretical technical parameters of the spare soluble bridge plugs for development wells in a certain block of the South China Sea.

[0042] Figure 8 This is a schematic diagram of the indoor bridge plug test simulation well and the intelligent high-temperature and high-pressure test system in the example.

[0043] Figure 9The pressure-time curve during the simulated bridge plug release and setting test in the example.

[0044] Figure 10 The pressure-time curves are shown in the example during the pressure bearing test of the bridge plug before and during the in-compression fracturing seal. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0046] See Figures 1-10 A bridge plug testing method based on construction characteristics under simulated reservoir conditions includes the following steps:

[0047] Step 1: Determine the indoor simulation test conditions and procedures, and screen candidate bridge plugs for testing, including the following sub-steps:

[0048] Step 1.1: Collect geological data of the development well for indoor simulation of the initial conditions of the reservoir environment; the data includes the formation depth of the development well, the initial temperature of the wellbore, the initial pressure of the wellbore, the salinity of the reservoir fluid, and the acidity and alkalinity of the fluid;

[0049] Step 1.2: Determine the mine construction process and the construction parameters corresponding to different construction stages based on the geological data in Step 1.1, for indoor simulation of the reservoir environment at different construction stages; the construction parameters include pumping discharge rate, well run-in time, wellbore temperature and pressure conditions at different stages, and fracturing process parameters.

[0050] Step 1.3: Based on the geological data of the development well in Step 1.1 and the construction conditions and procedures in Step 1.2, a preliminary screening of the type, size, structure, and material of the bridge plugs required for the development well is conducted. The preliminary screening determines that the bridge plug types that meet the requirements are A, B, C, etc., with n bridge plugs of each type. Before testing, the factory theoretical parameters of different types of candidate bridge plugs are determined, including key theoretical parameters such as the maximum outer diameter D0, the minimum inner diameter d0, the overall length L0, the overall weight G0, and the setting and release value Q0, so as to facilitate subsequent comparison with actual test values ​​and evaluation of the overall performance of the bridge plugs.

[0051] Step 2: Under simulated reservoir conditions based on construction characteristics, randomly test one type of n (n greater than or equal to 3) candidate bridge plugs. When three consecutive bridge plugs meet the test conditions, it means that the bridge plug of this type meets the requirements, and proceed to Step 3; when two bridge plugs do not meet the test conditions, return to Step 1 and reselect another type of bridge plug; the test content is the test content in Step 5 below.

[0052] Step 2.1: Bridge plug appearance and dimensions test

[0053] The appearance parameters of the candidate bridge plugs are measured using measuring instruments, including the maximum outer diameter D1, the minimum inner diameter d1, the overall length H1, and the overall weight G1. The measured data are compared with the theoretical parameters of the candidate bridge plugs: maximum outer diameter D0, minimum inner diameter d0, overall length H0, and overall weight G0. If the difference in the corresponding dimensional parameters is ≤0.1mm and the difference in weight is ≤500g, it proves that the appearance dimensions of the candidate bridge plugs meet the test requirements, and the next step, step 2.2, is performed; otherwise, the test of that bridge plug is stopped, and the next bridge plug is tested.

[0054] Step 2.2: Simulated bridge plug downhole pumping test

[0055] The simulated well is filled with test fluid and heated to a specified temperature T1. The bridge plug is then placed into the simulated well and pressurized to a specified pressure P1. After the pressure stabilizes, the bridge plug is immersed in the well for a specified time t1 while maintaining the temperature and pressure. After immersion, the bridge plug is removed. The surface condition of the bridge plug is observed, and the appearance parameters of the bridge plug, namely the maximum outer diameter D2, the minimum inner diameter d2, the overall length H2, and the overall weight G2, are measured again and compared with the corresponding theoretical parameters. If the difference in the corresponding parameters is ≤0.5mm and the difference in weight is ≤500g, the next step 2.3 can be performed; otherwise, the test of the bridge plug is stopped, and the next bridge plug test is performed.

[0056] Step 2.3: Simulated bridge plug release and setting test

[0057] Under normal temperature and pressure conditions on the ground, assemble the bridge plug and the corresponding bridge plug setting tool and set them inside the test sleeve short section. Then, perform pressure testing or gunpowder setting and record the test drop value Q1. By comparing it with the theoretical drop value Q0 of the bridge plug, and through ground pressure testing, determine whether the bridge plug is set well and whether the rubber barrel is properly opened: the error between the measured drop value and the theoretical drop value of the bridge plug should not exceed 2 tons, which proves that the drop value is normal; if the error exceeds 2 tons, it indicates that the drop value is abnormal; if the drop value of the candidate bridge plug is normal and the ground pressure testing is normal, it proves that the candidate bridge plug is set well and the rubber barrel is properly opened, and the next step 2.4 test can be carried out; otherwise, stop testing the bridge plug and proceed to the next bridge plug test.

[0058] Step 2.4: Simulated bridge plug pre-fracturing seal pressure test

[0059] After setting, the bridge plug is sealed using a ball or plug, and then lowered back into a simulated well containing test fluid. The bridge plug is heated and pressurized to a specified temperature and pressure, and then soaked under heat and pressure. The pressure-time change curve is recorded during the soaking period. The sealing and pressure-bearing performance of the bridge plug before fracturing is judged by the change curve. The specified temperature is T2, the specified pressure is P2, and the soaking time is t2. If the test pressure value of the candidate bridge plug is always within 5% above or below the set pressure threshold during the heat and pressure holding period, and the soaking time is also met, then the next step 2.5 test is performed; otherwise, the test of the bridge plug is stopped, and the next bridge plug is tested.

[0060] Step 2.5: Simulated bridge plug fracturing seal pressure test;

[0061] Continue heating and pressurizing the bridge plug from step 2.4 to the specified temperature and pressure, followed by heat preservation and pressure holding immersion. Record the pressure-time change curve during the immersion period. Use this curve to determine the sealing and pressure-bearing performance of the bridge plug in fracturing. The specified temperature is T3, the specified pressure is P3, and the immersion time is t3. If, during the heat preservation and pressure holding period, the test pressure value of the candidate bridge plug is always based on the design pressure value and fluctuates within 5% above or below the base value, and the test time is also met, then proceed to the next step, step 2.6; otherwise, stop testing the bridge plug and proceed to the next bridge plug test.

[0062] Step 2.6: Simulate bridge plug fracturing post-dissolution performance test or drilling performance test

[0063] Post-fracturing dissolution performance tests were conducted on soluble bridge plugs: Under ambient temperature and pressure conditions on the ground, the bridge plugs tested in step 2.5 were further immersed in a test fluid solution at temperature T1 for dissolution performance testing. The remaining products were analyzed at time intervals t, and data such as bridge plug dissolution time, residue mass, maximum size of residue monomers, and residue percentage were recorded to evaluate dissolution performance. Post-fracturing drilling performance tests were conducted on composite bridge plugs: Under ambient temperature and pressure conditions on the ground, the bridge plugs tested in step 2.5 were drilled on a machine tool, and the drilling time, drill cuttings, and residue weight were recorded to evaluate drilling performance.

[0064] Step 3: Conduct an overall performance evaluation of all candidate bridge plugs. If they meet the evaluation criteria, they can be deployed to the well. If they do not meet the evaluation criteria, return to Step 1 and select a new candidate bridge plug type.

[0065] Preferably, the bridge plug type mentioned in step 1.3 includes soluble bridge plugs and composite bridge plugs;

[0066] Preferably, the test fluid in step 2.2 is a real well fluid sample from a development well or a prepared solution with the same percentage of chloride salinity and pH.

[0067] Preferably, the specified temperature T1, specified pressure P1, and specified time t1 in step 2.2 should be based on the initial wellbore temperature T0, initial wellbore pressure P0, and the time t0 required to run the bridge plug into the well during the actual pumping stage of the bridge plug.

[0068] Preferably, the bridge plug setting tool mentioned in step 2.3 includes a disposable direct-push bridge plug setting tool, a hydraulic setting tool, or other Beck series setting tools that match the bridge plug model;

[0069] Preferably, the dimensions, weight, material, yield strength, and maximum internal pressure resistance of the sleeve subsection described in step 2.3 should meet the bridge plug test conditions.

[0070] Preferably, if the error between the measured drop value Q1 and the theoretical drop value Q0 of the bridge plug in step 2.3 does not exceed 2 tons, it proves that the setting is normal. If the error exceeds 2 tons, it indicates that the drop value of the bridge plug is abnormal and there is a possibility that the setting is not firm.

[0071] Preferably, the specified temperature T2, specified pressure P2, and specified time t2 in step 2.4 should be based on the wellbore temperature T at which the bridge plug is located after the development well is perforated again. 01 Formation pressure P 01 and fracturing preparation time t 01 For reference, T2 > T1 and P2 > P1 should be true;

[0072] Preferably, the specified temperature T3, specified pressure P3, and specified time t3 in step 2.5 should be based on the wellbore temperature T at which the bridge plug is located during the fracturing process of the development well. 02 Wellbore pressure P 02 and the time required for fracturing (t) 02 For reference, T3 = T2 and P3 > P2;

[0073] Preferably, the specified pressures P1, P2, and P3 mentioned in steps 2.2, 2.4, and 2.5 can fluctuate by up to 5% during the actual test. If the fluctuation exceeds the upper limit, an automatic pressure relief operation is required; if the fluctuation is below the lower limit, an automatic pressure replenishment operation is required.

[0074] Preferably, if the pressure-time variation curves within the specified time intervals t2 and t3 described in steps 2.4 and 2.5 are smooth and stable, it indicates that the bridge plug has good sealing and pressure-bearing performance under simulated temperature and pressure conditions; if the pressure-time variation curves within the specified time intervals t2 and t3 drop significantly and automatic pressure replenishment fails, it indicates that the bridge plug has poor sealing and pressure-bearing performance under simulated temperature and pressure conditions and there is a possibility of leakage. The pressure corresponding to the significant pressure drop is the maximum pressure limit of the bridge plug.

[0075] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0076] A bridge plug testing method based on construction characteristics under simulated reservoir conditions, the testing procedure of which is as follows: Figure 1 As shown, the specific steps include:

[0077] Step 1: Determine the indoor simulation test conditions and procedures, and screen candidate bridge plugs for testing.

[0078] Step 1.1: Geological data collection for development wells

[0079] A certain block in the South China Sea is dominated by sandstone reservoirs, with a burial depth of 3300m-4100m. The seawater salinity in the operating area is 30000ppm, the pH of the seawater is 7.8-8.5, the initial wellbore temperature is 96℃, and the initial wellbore pressure is 38MPa. This test method is now used to conduct a system performance test on the bridge plug used in this offshore development well before construction to ensure construction quality and safety.

[0080] Step 1.2: Determine the construction process and construction parameters for different stages.

[0081] This offshore development well employed a perforation-assisted staged fracturing technique, with a pumping rate of 3.5-6 m³ / h during construction. 3 / min, downhole time approximately 4 hours;

[0082] Step 1.3: Determine the alternative bridges for testing

[0083] Because the reservoir in this development well is deep and the construction pressure is high, it is difficult to drill and grind the bridge plug after fracturing. Therefore, a soluble bridge plug was selected as the alternative bridge plug. Its theoretical parameters are shown in Table 1.

[0084] Table 1 shows the theoretical technical parameters of the spare soluble bridge plugs for development wells in a certain block of the South China Sea.

[0085]

[0086]

[0087] Step 2: Bridge plug testing under simulated reservoir conditions based on construction characteristics

[0088] Step 2.1 Bridge plug appearance and dimensions test

[0089] The external dimensions of the bridge plug were measured using measuring instruments according to the testing procedure. The test results are as follows: the maximum outer diameter of the bridge plug D1 = 106.41 mm, the minimum inner diameter d1 = 45.00 mm, the overall length H1 = 482.86 mm, and the overall weight G1 = 8.66 kg. These measured data meet the test requirements of dimensional difference ≤ 0.5 mm and weight difference ≤ 500 g, which are consistent with the theoretical technical parameters of the bridge plug.

[0090] Step 2.2 Simulated bridge plug downhole pumping test

[0091] According to the procedure, the simulated well was filled with seawater samples and heated to 100°C using an intelligent high-temperature and high-pressure testing system. After the internal and external conditions were balanced, the bridge plug was lowered into the simulated well via suspension. The oil pressure was increased to 40 MPa, and after the pressure stabilized, the bridge plug was immersed in the simulated well for a specified time of 5 hours under heat and pressure. After immersion, the bridge plug was removed from the simulated well. After testing, the bridge plug's appearance surface was normal and showed no dissolution. The bridge plug's dimensions were re-examined and found to be: maximum outer diameter D2 = 106.63 mm, minimum inner diameter d2 = 44.90 mm, overall length H2 = 482.88 mm, and overall weight G2 = 8.70 kg. These dimensions meet the test requirements of ≤0.1 mm difference and ≤500 g difference, indicating that the simulated well-running process had no impact on the bridge plug.

[0092] Step 2.3 Simulate bridge plug release and setting test

[0093] Under normal temperature and pressure conditions, the soluble bridge plug was assembled and set in a short section (P110) with a length of 1000mm, an inner diameter of 118.6mm, and an outer diameter of 5-1 / 2in using a Baker 20# setting tool. The pressure was increased until the soluble bridge plug was released. After release, the upper and lower end faces of the bridge plug were in good condition. The release pressure curve showed that the release value was 42.62MPa (19.7t), which is consistent with the theoretical release value of 18t±2t, indicating that the simulated bridge plug release and setting was good.

[0094] Step 2.4 Simulated bridge plug pre-fracturing seal pressure test

[0095] The soluble bridge plug's internal channel within the casing was sealed using a ball or plug. The casing was then connected to the test system string, a pressurization line was connected, and the casing was lowered into a simulated well containing a real seawater sample. The temperature was raised to 130℃ and the pressure increased to 50MPa using an intelligent high-temperature and high-pressure test system. After immersion in the solution for 5 hours, a pressure test was conducted to simulate the bridge plug's pre-fracturing pressure. The pressure-time curve showed that during immersion at 150℃ and 45MPa for 300 minutes, the bridge plug remained stable except for automatic pressure relief to control the test pressure. No leakage was observed, indicating that the bridge plug was firmly set and the simulated pre-fracturing pressure test was successful.

[0096] Step 2.5 Simulated bridge plug fracturing seal pressure test

[0097] The temperature was further increased to 150℃ and the oil pressure to 70MPa using an intelligent high-temperature and high-pressure testing system. After stabilizing the pressure and immersing for another 5 hours, a pressure test was conducted to simulate the pressure bearing capacity of the bridge plug during fracturing. The pressure-time curve shows that during the immersion of the bridge plug at 150℃ and 70MPa for 300 minutes, the curve remained stable except for automatic pressure relief to control the test pressure. No pressure drop was observed, indicating that the bridge plug performed well in the simulated fracturing sealing pressure test and met the conditions for high-temperature and high-pressure use.

[0098] Step 2.6 Simulated bridge plug fracturing dissolution test

[0099] The soluble bridge plug was immersed in a real seawater sample solution at 100°C, and the remaining product was analyzed every 24 hours. The soluble ball completely dissolved on the second day, and the soluble bridge plug completely dissolved on the sixth day, almost dissolving into a mud-like substance.

[0100] Step 3: Overall performance evaluation of bridge plugs

[0101] During actual testing, the soluble bridge plug passed the complete set of test procedures three times in a row, and all of them met the theoretical technical specifications of the factory. That is, the overall performance of this type of soluble bridge plug meets the operational requirements of different construction stages, and the effect after being used in the well is significant.

[0102] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

[0103] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A bridge plug testing method based on construction characteristics under simulated reservoir conditions, characterized in that, Includes the following steps: Step 1: Determine the indoor simulation test conditions and procedures, and screen candidate bridge plugs for testing, including the following sub-steps: Step 1.1: Collect geological data of the development well for indoor simulation of the initial conditions of the reservoir environment; the data includes the formation depth of the development well, the initial temperature of the wellbore, the initial pressure of the wellbore, the salinity of the reservoir fluid, and the acidity and alkalinity of the fluid; Step 1.2: Determine the mine construction process and the construction parameters corresponding to different construction stages based on the geological data in Step 1.1, for indoor simulation of the reservoir environment at different construction stages; the construction parameters include pumping discharge rate, well run-in time, wellbore temperature and pressure conditions at different stages, and fracturing process parameters. Step 1.3: Based on the geological data of the development well in Step 1.1 and the construction conditions and parameters in Step 1.2, a preliminary screening of the type, size, structure, and material of the bridge plugs required for the development well is conducted. The preliminary screening determines that the bridge plug types that meet the requirements are A, B, C, etc., and the quantity of each type of bridge plug is n. Before testing, the theoretical parameters of the different types of candidate bridge plugs are determined. Step 2: Under simulated reservoir conditions based on construction characteristics, randomly test n candidate bridge plugs of one type, where n is greater than or equal to 3. When three consecutive bridge plugs meet the test conditions, it indicates that this type of bridge plug meets the requirements, and proceed to Step 3; when two bridge plugs fail to meet the test conditions, return to Step 1 and select another type of bridge plug. The test includes the following sub-steps: Step 2.1: Bridge plug appearance dimension test; Measure the appearance parameters of the candidate bridge plugs, including the maximum outer diameter of the bridge plug. , minimum inner diameter of bridge plug Overall length of bridge plug Overall weight of bridge plug The measured data were compared with the theoretical parameters of the candidate bridge plugs, including the maximum outer diameter of the bridge plug. , minimum inner diameter of bridge plug Overall length of bridge plug Overall weight of bridge plug Compare the parameters. If the difference in the corresponding dimensions is ≤0.5mm and the difference in weight is ≤500g, it proves that the appearance dimensions of the candidate bridge plug meet the test requirements, and proceed to the next step, test content 2.2; otherwise, stop testing the bridge plug and proceed to the next bridge plug test. Step 2.2: Simulate bridge plug downhole pumping test. Fill the indoor simulated well with test fluid and heat the test fluid to the specified temperature. Then, the bridge plug is placed into the simulated well; pressurization is then applied to the specified pressure. After the pressure stabilizes, soak the bridge plug in a heat-insulating and pressure-maintaining solution for the specified time. Remove the bridge plug after soaking is complete; Observe the surface condition of the bridge plug and re-examine the appearance parameters of the bridge plug, including its maximum outer diameter. , minimum inner diameter of bridge plug Overall length of bridge plug Overall weight of bridge plug Perform measurements and compare them with the corresponding theoretical parameters of the bridge plug. If the size difference of the corresponding parameters is ≤0.5mm and the weight difference is ≤500g, proceed to the next step, step 2.3; otherwise, stop testing the bridge plug and proceed to the next bridge plug test. Step 2.3: Simulate bridge plug release and setting test. Under normal temperature and pressure conditions on the ground, assemble the bridge plug and the corresponding bridge plug setting tool and set it inside the test sleeve short section. Then, perform pressure testing or explosive setting and record the test release value. By comparing the theoretical drop value of bridge plugs The test involves ground pressure testing to determine if the bridge plug is properly set and if the rubber drum is properly opened. If the difference between the measured release value and the theoretical release value of the bridge plug does not exceed 2 tons, the release value is considered normal. If the difference exceeds 2 tons, the release value is considered abnormal. If the release value of the candidate bridge plug is normal and the ground pressure test is normal, it proves that the candidate bridge plug is properly set and the rubber drum is properly opened, and the next step, step 2.4, can be performed. Otherwise, the test of the bridge plug is stopped, and the next bridge plug test is performed. Step 2.4: Simulate the sealing pressure test before bridge plug fracturing; Step 2.5: Simulated bridge plug fracturing seal pressure test; Step 2.6: Simulate the dissolution performance test or drilling performance test after bridge plug fracturing. The dissolution performance test is for soluble bridge plugs, and the drilling performance test is for composite bridge plugs. Step 3: Conduct an overall performance evaluation of all candidate bridge plugs. If they meet the evaluation criteria, they can be deployed to the well. If they do not meet the evaluation criteria, return to Step 1 and select a new candidate bridge plug type.

2. The bridge plug testing method based on construction characteristics under simulated reservoir conditions as described in claim 1, characterized in that, In step 2.4, the set bridge plug is sealed using a ball or plug, and then lowered back into a simulated well containing test fluid. The bridge plug is heated and pressurized to a specified temperature and pressure, followed by heat and pressure holding immersion. Pressure-time curves are recorded during the immersion period. These curves are used to determine the sealing and pressure-bearing performance of the bridge plug before fracturing. The specified temperature is... The specified pressure is Soaking time If, during the heat preservation and pressure preservation period, the test pressure value of the candidate bridge plug is always based on the designed pressure threshold and fluctuates within 5% above or below the threshold, and the soaking time is also met, then proceed to the next step, test content 2.5; otherwise, stop testing the bridge plug and proceed to the next bridge plug test.

3. The bridge plug testing method based on construction characteristics under simulated reservoir conditions as described in claim 2, characterized in that, In step 2.5, the bridge plug from step 2.4 is further heated and pressurized to a specified temperature and pressure, followed by heat and pressure holding immersion. The pressure-time change curve is recorded during the immersion period. This curve is used to determine the sealing and pressure-bearing performance of the bridge plug in fracturing. The specified temperature is... The specified pressure is Soaking time If, during the heat preservation and pressure maintenance period, the test pressure value of the candidate bridge plug is always based on the design pressure value and fluctuates within 5% above or below the design pressure value, and the test time is also met, then proceed to the next step, step 2.6; otherwise, stop testing the bridge plug and proceed to the next bridge plug test.

4. The bridge plug testing method based on construction characteristics under simulated reservoir conditions as described in claim 1, characterized in that, Step 2.6 includes the following: (1) Post-fracturing dissolution performance test of soluble bridge plugs: Under normal temperature and pressure conditions on the ground, the bridge plug tested in step 2.5 was further immersed in an environment at a temperature of [temperature missing]. The solubility test was conducted in the test fluid solution at each interval. The remaining products were analyzed over time, and the dissolution time of the bridge plug, the mass of the residue, the maximum size of the residue monomers, and the percentage of residue were recorded to evaluate the dissolution performance. (2) Post-fracturing drilling performance test of composite bridge plugs: Under normal temperature and pressure conditions on the ground, the bridge plug tested in step 2.5 was drilled and ground on a machine tool. The drilling and grinding time, the weight of drill chips and residues were recorded to evaluate the drilling and grinding performance.

5. The bridge plug testing method based on construction characteristics under simulated reservoir conditions as described in claim 1, characterized in that, The test fluid in step 2.2 is a real well fluid sample from the development well or a prepared solution with the same percentage of chloride mineralization and pH.

6. The bridge plug testing method based on construction characteristics under simulated reservoir conditions as described in claim 3, characterized in that, The relationship between the specified temperature and the specified pressure is as follows: .

7. The bridge plug testing method based on construction characteristics under simulated reservoir conditions as described in claim 6, characterized in that, The specified pressure During actual testing, the pressure can fluctuate up or down by a maximum of 5%. If the pressure exceeds the upper limit, an automatic pressure relief operation is required; if the pressure falls below the lower limit, an automatic pressure replenishment operation is required.

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