Method for evaluating plugging pressure-bearing performance of temperature-sensitive adhesive plugging material for deep fractured formation

Abstract

The invention discloses a method for evaluating the plugging pressure-bearing performance of a temperature-sensitive bonding plugging material for a deep fractured formation, and belongs to the technical field of leakage control, and the method comprises the following steps: preparing a cylindrical sample from the temperature-sensitive bonding plugging material according to a preset size, the preset size comprising the diameter and the length of the sample; measuring the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength; according to the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength, the pressure-bearing performance of the temperature-sensitive adhesive plugging material is evaluated, and the larger the quotient of the uniaxial compressive strength and the strain corresponding to the uniaxial compressive strength is, the better the pressure-bearing performance of the plugging layer is. According to the method for scientifically evaluating the pressure-bearing performance of the temperature-sensitive bonding plugging material, the mechanical performance and the sealing performance of the material are systematically quantified by combining stress and strain, the pressure-bearing performance of the material under the actual working condition can be accurately reflected, the accuracy of the evaluation result is high, meanwhile, the evaluation parameters are mainly based on the result of a compression test, and the evaluation accuracy is high. The operation is simple.

Description

Technical Field

[0001] The invention belongs to the technical field of leakage control and also relates to new material detection and function testing, and specifically is a method for evaluating the sealing and pressure bearing performance of a temperature-sensitive adhesive plugging material in a deep fractured formation. Background Art

[0002] Thermosensitive adhesive plugging material is a plugging material that does not solidify at room temperature. When it reaches a certain temperature, it can cross-link with amine cross-linking agents to form a solid solid. This is conducive to its consolidation into a plug under the bottom hole temperature conditions, plugging the leakage channel and enhancing the retention capacity of the plugging material in the leakage channel. It is particularly suitable for the high temperature and high pressure environment of deep fractured formations. There are many existing thermosensitive adhesive plugging materials, such as a thermosensitive material disclosed by Wang Weiji et al. (Preparation and properties of thermosensitive poly (NIPAm-co-AA) / nano-SiO 2 composite blocking agent for shale gas reservoir[J]. Acta Petrolei Sinica, 2015, 36(3): 378-384. ).

[0003] Thermosensitive adhesive plugging materials enhance the pressure-bearing performance of the plugging layer by improving the bonding force between particles and between particles and crack surfaces. At present, the pressure-bearing plugging test is generally used to screen the thermosensitive adhesive plugging materials, but the pressure-bearing plugging test requires the configuration of drilling fluid, crack models, etc., and the plugging materials need to be graded. The operation is cumbersome, time-consuming, and the experimental error is large. Therefore, there is an urgent need for a fast and effective way to evaluate the performance of thermosensitive adhesive plugging materials. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for evaluating the pressure-bearing performance of temperature-sensitive adhesive plugging materials in deep fractured formations. The present invention uses the uniaxial compressive strength of the plugging layer and the strain corresponding to the uniaxial compressive strength to evaluate the pressure-bearing performance of the plugging layer, which can significantly improve the accuracy of the evaluation.

[0005] In order to achieve the above object, the solution provided by the present invention is as follows: A method for evaluating the sealing pressure bearing performance of a temperature-sensitive adhesive plugging material in a deep fractured formation comprises the following steps: S1. Use a temperature-sensitive adhesive sealing material to make a cylindrical specimen according to preset dimensions, where the preset dimensions include the diameter and length of the specimen; S2. Determine the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength; S3. The pressure-bearing performance of the temperature-sensitive adhesive plugging material is evaluated according to the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength. The greater the quotient of the uniaxial compressive strength and the strain corresponding to the uniaxial compressive strength, the better the pressure-bearing performance of the plugging layer.

[0006] In the present invention, the uniaxial compressive strength of the sample is related to its size. When the aspect ratio is very small, the uniaxial compressive strength of the sample is very large. When the aspect ratio is very large, the sample is easily damaged due to elastic instability and uneven stress distribution, which reduces the uniaxial compressive strength of the sample. As a specific embodiment of the present invention, the aspect ratio of the sample is 2 to 3.

[0007] In the present invention, the uniaxial compressive strength can be measured by using a measuring device in the prior art, and then a stress-strain curve is plotted. The peak intensity of the curve is the uniaxial compressive strength of the sample.

[0008] As a specific implementation of the present invention, in step S1, the preset size is a diameter of 50 mm and an aspect ratio of 2; in step S3, the bonding performance evaluation index is used to evaluate the pressure bearing performance of the temperature-sensitive bonding plugging material, wherein the calculation formula of the bonding performance evaluation index is as follows:

[0009] In the formula, B It is the bonding performance evaluation index, ranging from 0 to 1, and the larger the value, the better the performance; б max is the uniaxial compressive strength, i.e., peak strength, MPa; ε is the strain, i.e. the strain corresponding to the peak intensity; Furthermore, step S3 also includes determining the pressure-bearing performance grade of the temperature-sensitive adhesive sealing material according to the bonding performance evaluation index and assessment criteria, wherein the assessment criteria include: 0≤B≤0.2, weak pressure-bearing performance; 0.2<B≤0.4, relatively weak pressure-bearing performance; 0.4<B≤0.6, medium pressure-bearing performance; 0.6<B≤0.8, medium to strong pressure-bearing performance; 0.8<B≤1, strong pressure-bearing performance.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for scientifically evaluating the pressure-bearing performance of temperature-sensitive adhesive sealing materials, which combines stress and strain to systematically quantify the mechanical properties and sealing performance of the material, can accurately reflect the pressure-bearing performance of the material under actual working conditions, and the evaluation results are highly accurate. At the same time, the evaluation parameters are mainly based on the results of the compression test, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the stress-strain curve of the temperature-sensitive adhesive plugging material with LCC200 as the core; Figure 2 This is the stress-strain curve of the temperature-sensitive adhesive plugging material with walnut shell as the core; Figure 3 It is the stress-strain curve of the temperature-sensitive adhesive plugging material with pore basalt as the core. DETAILED DESCRIPTION

[0012] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0013] In this embodiment, a warm-press plug module pressing instrument is used to press the sample, and a microcomputer-controlled electronic universal testing machine model ETM305D is used to measure the stress-strain data of the sample. It should be known to those skilled in the art that the instrument capable of implementing the present invention is not limited to the above instrument. At the same time, the "cross-sectional area" in the embodiment is the maximum cross-sectional area measured by the column formed by the module pressing instrument.

[0014] In the following examples, LCC200 particles come from Chengdu Dedao Industrial Co., Ltd., which is a high-strength inert granular material that does not react with acid and has a mass crushing rate of 4.1% under a pressure of 30.0 MPa; E-12 and E-20 are both thermosetting epoxy resins, of which E-12 comes from Xuzhou Huisheng Electronic Materials Co., Ltd. and E-20 comes from Sinopec Baling Petrochemical Co., Ltd.; GZD comes from Sichuan Southwest Shida Jinniu Petroleum Technology Co., Ltd., which is an acid-soluble filling material with a mesh size of 18 to 24.

[0015] Example 1: S1, using a temperature-sensitive adhesive plugging material to prepare a cylindrical sample, comprising the following steps: S11. Preparation of temperature-sensitive adhesive plugging material: LCC200 particles (6-10 mesh) are used as core material, and epoxy resin E-12 is used as thermosetting resin. After washing and drying the core material, the total mass is weighed. Based on the mass of the core material after drying, 10wt% of epoxy resin, 0.1wt% of dicyandiamide (curing agent), 0.1wt% of silane coupling agent (interface modifier) ​​and 0.2wt% of dimethylimidazole (catalyst) are weighed for use. Epoxy resin and dichloromethane are mixed and stirred at a mass ratio of 1:3 until completely dissolved, and dicyandiamide is added and stirred continuously to form a homogeneous solution, which is called epoxy resin. lipid solution; dissolve dimethylimidazole in anhydrous ethanol to prepare a catalytic system, then add a silane coupling agent (γ-aminopropyltriethoxysilane) and an epoxy resin solution and mix and stir for 5 minutes to form a mixed solution; move the mixed solution and the core material particles into the coating machine trough, and add dichloromethane to completely immerse the particle layer; start the coating machine that has been preheated to 50°C and keep rotating at a constant speed, and accelerate the evaporation of the solvent through the hot air circulation system; stop the machine after a uniform coating layer is formed, and transfer the coated particles to a cooling plate to naturally cool to room temperature; finally, gently rub the agglomerated particles to obtain a temperature-sensitive adhesive sealing material with uniform particle size.

[0016] S12. Prepare plugging slurry: based on the total mass of water, weigh 0.1wt% of sodium hydroxide, 0.2wt% of sodium carbonate, 6wt% of bentonite, 0.4wt% of sodium carboxymethyl cellulose (CMC) and 0.4wt% of xanthan gum for use; dissolve sodium hydroxide and sodium carbonate in water, stir well and slowly add CMC and xanthan gum, then add bentonite to the solution, mix thoroughly until uniform and viscous, and let it stand for 10 minutes before use.

[0017] S13. Mix the temperature-sensitive adhesive plugging material prepared in S11 and the plugging slurry prepared in S12 in a mass ratio of 1:4, inject into a warm pressure plug module pressing instrument, and cure for 6 hours at a temperature of 90°C and a pressure of 1 MPa to obtain a sample.

[0018] The sample was removed from the instrument, cooled to room temperature and its dimensions were measured. The specific dimensions are shown in Table 1.

[0019] S2. Determine the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength. This step uses an electronic universal testing machine to perform uniaxial mechanical property tests on the cured sample. The specific steps are as follows: S21. Place the sample in the fixture of the testing machine, ensuring that the loading direction of the sample is consistent with the pressure axis of the equipment; S22, using uniform acceleration loading method, loading rate of 0.5mm / min, gradually apply external pressure until the sample breaks, stop loading, record the column deformation and stress data, and draw a stress-strain curve based on the test data, such as Figure 1 As shown; S23. The uniaxial compressive strength of the sample and its corresponding strain are obtained according to the stress-strain curve, see Table 1.

[0020] S3. Evaluate the bonding performance evaluation index of the plugging layer according to the uniaxial compressive strength of the sample and its corresponding strain; .

[0021] Example 2: The steps of this example are the same as those of Example 1, except that the samples of the two are different. The sample of this example is prepared with walnut shell particles (6-8 mesh) as the core material according to the steps of Example 1.

[0022] The dimensions of the sample in this embodiment are shown in Table 1, and its stress-strain curve is shown in Figure 2 The evaluation indicators of uniaxial compressive strength, strain and bonding performance are shown in Table 2.

[0023] Example 3: The steps of this example are the same as those of Example 1, except that the samples are different. The sample of this example uses porous basalt (6-10 mesh) as the core material and epoxy resin E-20 as the thermosetting resin, and is prepared according to the steps of Example 1.

[0024] The dimensions of the sample in this embodiment are shown in Table 1, and its stress-strain curve is shown in Figure 3 The evaluation indicators of uniaxial compressive strength, strain and bonding performance are shown in Table 2.

[0025] Table 1 Dimensions of each sample

[0026] Table 2 Uniaxial test results and bonding performance evaluation index of each sample

[0027] Finally, the bonding performance evaluation index of Example 1 is 0.933, and the pressure-bearing performance is strong; the bonding performance evaluation index of Example 2 is 0.460, and the pressure-bearing performance is medium; the bonding performance evaluation index of Example 2 is 0.889, and the pressure-bearing performance is strong. The three are ranked in descending order of performance as follows: Example 1, Example 3, and Example 2.

[0028] Test Example 1 In order to verify the accuracy of the bonding performance evaluation index in evaluating the pressure bearing performance, a plugging material is prepared using the temperature-sensitive bonding plugging material in the above embodiment, and a pressure bearing plugging experiment is carried out to measure the actual pressure bearing performance of each material, which specifically includes the following steps: The temperature-sensitive adhesives prepared in Examples 1 to 3 were used as bridging materials and GZD was used as filling materials to prepare plugging formulas. The amount of each substance in the plugging formula was based on the mass of water in the plugging slurry base. The specific formula is shown in Table 3.

[0029] The formula of plugging slurry base slurry is: water + 4wt% bentonite + 0.2wt% sodium carbonate + 0.1wt% sodium hydroxide + 0.3wt% sodium carboxymethyl cellulose + 0.4wt% xanthan gum. The above addition amounts are based on the mass of water.

[0030] Table 3 Composition of each plugging formula

[0031] (2) The positive pressure bearing capacity test of the crack plugging layer includes the following steps: placing a variable width crack rock sample with an initial crack width of 5.0-3.0 mm (the initial width of the crack entrance is 5.0 mm, and the initial width of the crack exit is 3.0 mm) into a core holder with a heater, applying a confining pressure of 25 MPa, closing the valve downstream of the core holder, pouring the prepared plugging slurry into the kettle upstream of the core holder, turning on the electric mixer in the kettle, and setting the speed to 150 r / min; turning on the water pump connected to the kettle, The pressure in the kettle was increased to 1.0 MPa at a rate of 1 mL / min. After stabilizing the pressure for 5 minutes, the heater was turned on and the temperature was set to 90 °C. After reaching the set temperature for 30 minutes, the valve downstream of the core holder was opened and the initial leakage was recorded. The pressure in the kettle was increased at a rate of 1 mL / min. When the pressure in the kettle dropped sharply and did not recover, the fracture plugging layer was considered to be damaged, and the experiment was stopped. The peak pressure was recorded as the pressure bearing capacity of the fracture plugging layer, and the final leakage at the peak pressure was recorded as the cumulative leakage. The test results of the forward pressure bearing capacity of the fracture plugging layer of each plugging formula are shown in Table 4.

[0032] Table 4 Test results of positive pressure bearing capacity of crack sealing layer of each plugging formula

[0033] It can be seen from Table 4 that the pressure-bearing plugging performance of Formula 1 (using the temperature-sensitive adhesive plugging material of Example 1) is better than that of Formula 3 (using the temperature-sensitive adhesive plugging material of Example 3), and the pressure-bearing plugging performance of Formula 3 is better than that of Formula 2 (using the temperature-sensitive adhesive plugging material of Example 2). The evaluation results are the same as the evaluation results directly using the bonding performance evaluation index. The relative size of the pressure-bearing plugging performance of the formula can be determined by the relative size of the bonding performance evaluation index, thereby replacing the pressure-bearing plugging performance test with the uniaxial compressive performance test.

[0034] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the embodiments of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for evaluating the sealing pressure bearing performance of temperature-sensitive adhesive plugging materials in deep fractured formations, characterized in that: include: S1. Using a temperature-sensitive adhesive plugging material to make a cylindrical sample according to a preset size, wherein the preset size includes a diameter and a length of the sample; S2. Determine the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength; S3. Evaluate the pressure-bearing performance of the temperature-sensitive adhesive plugging material according to the uniaxial compressive strength of the sample and the strain corresponding to the uniaxial compressive strength. The greater the quotient of the uniaxial compressive strength and the strain corresponding to the uniaxial compressive strength, the better the pressure-bearing performance of the plugging layer.

2. The method for evaluating the sealing pressure bearing performance of temperature-sensitive adhesive plugging materials in deep fractured formations according to claim 1 is characterized in that: The aspect ratio of the sample is 2-3.

3. A method for evaluating the sealing pressure bearing performance of temperature-sensitive adhesive plugging materials in deep fractured formations according to claim 2, characterized in that: The preset size is 50 mm in diameter and 2 in aspect ratio; in step S3, the bonding performance is determined by using a bonding performance evaluation index, and in step S3, the bonding performance evaluation index is used to evaluate the pressure bearing performance of the temperature-sensitive bonding plugging material, and the calculation formula of the bonding performance evaluation index is as follows: ； In the formula, B It is an evaluation index of bonding performance; б max is the uniaxial compressive strength; ε For strain.

4. A method for evaluating the sealing pressure bearing performance of temperature-sensitive adhesive plugging materials in deep fractured formations according to claim 3, characterized in that: Step S3 also includes determining the pressure-bearing performance grade of the temperature-sensitive adhesive sealing material according to the bonding performance evaluation index and assessment criteria, wherein the assessment criteria include: 0≤B≤0.2, weak pressure-bearing performance; 0.2<B≤0.4, relatively weak pressure-bearing performance; 0.4<B≤0.6, medium pressure-bearing performance; 0.6<B≤0.8, medium to strong pressure-bearing performance; 0.8<B≤1, strong pressure-bearing performance.

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