A micro-test method for gel particle plugging performance

Abstract

The application discloses a kind of gel particle plugging performance micro test method, belong to oil and gas field profile control water plugging material performance test technical field.The application constructs micro simulation reservoir+constant pressure flow rate comparison using conventional laboratory equipment, without relying on complex equipment, to realize the quantification of gel particle plugging performance.The device used in the test method of the application is simple and has very low cost;The test is efficient and fast, and multiple samples can be tested in parallel, efficiently meeting the research and development needs of rapid screening of a large number of samples;The repeatability and accuracy are excellent;Wide application range, different types and different application scenarios of gel particle plugging performance test can be adapted by flexibly adjusting the glass bead size, injection pressure and gel particle suspension concentration, and the versatility is strong.

Description

Technical Field

[0001] This invention relates to the field of performance testing technology for profile control and water shut-off materials in oil and gas fields, specifically to a micro-testing method for the sealing performance of gel particles. Background Technology

[0002] In the mid-to-late stages of oil and gas field development, waterflooding leads to increased water cut, making profile control and water shut-off technologies crucial for enhancing oil recovery. Gel-based plugging agents, due to their excellent swelling, adsorption, and selective plugging capabilities, are widely used in oil and gas field profile control and water shut-off operations. Their plugging performance directly determines the effectiveness of profile control and water shut-off and the economic benefits of oilfield development. Therefore, rapid and accurate evaluation of the plugging ability of gel particles in the laboratory stage is a key step in screening high-quality plugging agents and optimizing formulations.

[0003] The existing gel particle plugging performance test mainly relies on traditional core displacement experimental devices. This technical solution has the following unavoidable defects: (1) The equipment is highly complex and requires high-pressure injection pumps, core holders, high-precision flow meters, pressure sensors and other precision equipment. The purchase cost of a single set of equipment exceeds RMB 50,000, and subsequent maintenance is difficult and expensive; (2) The test cycle is long. Core samples need to undergo pretreatment steps such as drying, saturated water, and displacement stabilization. The entire test process takes more than 12 hours, which cannot meet the research and development needs of rapid screening of a large number of candidate samples; (3) The operation threshold is high. The professional skills and equipment debugging experience of the experimental personnel are strictly required. Moreover, there are problems such as large batch differences in core samples, which leads to poor test repeatability (parallel error is usually ≥ ±5%); (4) There is serious waste of resources. For the early screening of small batches of samples by start-ups and research institutions, the use of large core displacement devices has problems of low equipment utilization and high test costs.

[0004] Therefore, developing a test method and device that is simple in structure, low in cost, easy to operate, and can quickly and accurately evaluate the blocking performance of gel particles, and overcoming the above-mentioned shortcomings of the existing technology, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing core displacement testing methods, such as complex equipment, high cost, long processing time, and poor repeatability, which prevent them from meeting the requirements for rapid screening of gel particle plugging performance in the laboratory, this invention provides a miniature testing method for gel particle plugging performance.

[0006] This invention provides a method for testing the plugging performance of gel particles. The apparatus used in the testing method includes a test body, a supporting filter layer, a simulated reservoir, and a constant pressure injection pump. The test body is a chromatography column or an acid burette; The lower end of the test body is filled with a support filter layer; glass beads are laid on the support filter layer as a simulated reservoir. The upper port of the test body is connected to a constant pressure injection pump via an injection pipeline; The testing method includes the following steps: (1) Turn on the constant pressure injection pump, inject water into the simulated reservoir, and measure the injection flow rate V0 after stabilization; (2) Inject a suspension of gel particles into the simulated reservoir and keep the injection pressure constant. After injecting the suspension of gel particles until the liquid surface is flush with the upper surface of the glass bead layer in the simulated reservoir, stop the injection and let it stand so that the gel particles can be fully adsorbed and retained in the pores of the simulated reservoir. (3) Inject water into the simulated reservoir and measure the injection flow rate V1 after stabilization; (4) Calculate the difference in water flow rate before and after injection of the gel particle suspension to quantify the sealing performance of the gel particles.

[0007] In the above testing method, the lower end of the testing body is equipped with a controllable flow rate valve outlet; The volume of the test subject is 20-100mL; The supporting filter layer is cotton; The glass beads have a particle size of 0.5-5mm and are laid up to a height of 1 / 3-1 / 2 of the effective volume of the test body.

[0008] The glass beads are used after being washed with water and dried at 105°C for 2 hours.

[0009] In the above testing method, the cotton is medical-grade absorbent cotton, with a filling thickness of 0.5-2 cm and a compaction degree of 0.3-0.6 g / cm³ after filling. 3 .

[0010] In the above test method, in step (1), the water injection flow rate V0 is measured after the water has stabilized for 30-60 minutes.

[0011] In the above test method, the settling time in step (2) is 2-4 hours.

[0012] In the above test method, in step (2), the mass percentage concentration of the gel particle suspension is 0.1%-5%; The gel particle suspension is injected under constant pressure, with an injection pressure of 0.05-0.5 MPa.

[0013] In the above test method, the water injection flow rate V0 and water injection flow rate V1 are determined by "collecting the mass of outflowing liquid per unit time + water density conversion", and the liquid collection time is 1-5 minutes.

[0014] In the above test method, in step (1), the injected water is injected under constant pressure, and the injection pressure is 0.05-0.5MPa.

[0015] In the above test method, in step (3), the injected water is injected under constant pressure, and the injection pressure is 0.05-0.5MPa.

[0016] In the above test method, step (4) uses the following formula to calculate the blocking performance of the gel particles: η = (V0 - V1) / V0 × 100%.

[0017] Where η is the plugging rate; V0 is the initial flow velocity in mL / min; and V1 is the flow velocity after plugging in mL / min.

[0018] The blocking performance of gel particles is quantified by the value of the blocking rate. The higher the blocking rate, the better the blocking effect of the gel particles.

[0019] The core innovation of this invention lies in "constructing a micro-simulated reservoir using conventional laboratory equipment + constant pressure flow rate comparison," which allows for the quantification of sealing performance without relying on complex equipment. In practical applications, the particle size of the small glass beads (to adapt to different reservoir porosity), injection pressure (to simulate pressure at different reservoir depths), and gel particle concentration (to adapt to actual construction concentrations) can be adjusted according to testing requirements, all of which are within the protection scope of this invention.

[0020] Compared with the prior art, the present invention has the following significant advantages: (1) The device is simple and the cost is extremely low: the test system is constructed using conventional laboratory acid burettes / chromatographic columns, medical degreased cotton and small glass beads. No precision instruments are required and the total cost of the equipment is ≤500 yuan, which is more than 90% lower than the traditional core displacement device, greatly reducing the test cost.

[0021] (2) The testing is efficient and fast: the entire testing cycle (including device assembly, bed stabilization, injection plugging and flow rate measurement) is ≤4h, which is more than 70% shorter than the traditional core displacement method (more than 12h). It can realize parallel testing of multiple sets of samples and efficiently meet the research and development needs of rapid screening of a large number of samples.

[0022] (3) Excellent repeatability and accuracy: The small glass beads have uniform particle size and stable chemical properties, avoiding batch differences in core samples. The parallel experiment error is ≤±5%, and the test results are more reliable, providing accurate data support for the screening of plugging agents.

[0023] (4) Low operating threshold: No complicated equipment debugging and professional skills training are required. Ordinary experimental personnel can complete the operation independently with simple guidance, which is suitable for the early research and development needs of different scenarios such as scientific research institutions and enterprise R&D departments.

[0024] (5) Wide range of applications: By flexibly adjusting the small glass bead particle size (to adapt to different reservoir porosity), injection pressure (to simulate different reservoir pressure conditions), and gel particle suspension concentration, it can be adapted to the gel particle plugging performance test of different types and application scenarios, and has strong versatility. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the testing device of the present invention; In the diagram: 1-Test body (chromatographic column / acid burette); 2-Supporting filter layer (medical absorbent cotton); 3-Simulated reservoir (small glass beads); 4-Controllable flow rate outlet; 5-Iron stand; 6-Constant pressure injection pump; 7-Injection pipeline; 8-Collection beaker. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0027] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0028] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0029] Example 1: Testing the Blocking Performance of Acrylamide Gel Particles Based on Chromatography Column 1. Testing Materials and Apparatus The main testing apparatus consists of a 50 mL glass chromatography column (1.6 cm inner diameter, 25 cm effective height) with a controllable flow rate valve at the bottom outlet.

[0030] Support for the filter assembly: Medical absorbent cotton, cut into 1.6cm diameter circles, 1cm thick, with a compacted density of 0.4g / cm³. 3 .

[0031] Simulated reservoir components: small glass beads (particle size 1-3mm, purity ≥99%), washed with deionized water and dried at 105℃ for 2 hours before use.

[0032] Test reagents: Acrylamide gel particles (particle size 50-100μm), deionized water, prepare 50mL of 1% (mass fraction) gel particle suspension. This acrylamide-based gel particle was developed in-house. It uses acrylamide as the core monomer, N,N'-methylenebisacrylamide as the crosslinking agent, and an ammonium persulfate-tetramethylethylenediamine redox system (mass ratio 1:1) as the initiator. The preparation method employed a reverse-phase suspension polymerization. The monomer (10 wt% aqueous phase) and crosslinking agent (1.0 wt% aqueous phase) were dissolved in deionized water to obtain an aqueous phase. This aqueous phase was then added dropwise to a white oil phase (water / oil phase volume ratio 1:4). Span 80 (4 wt% oil phase) was added as a dispersant and stabilizer, and an initiator (0.05 wt% aqueous phase) was added to initiate free radical crosslinking polymerization. The polymerization conditions were 40℃, 300 rpm, and stirring for 2.5 h to form spherical gel particles. Finally, the particles were washed alternately with ethanol and deionized water, dried at 50℃ for 12 h, ground, and sieved to obtain the final product. All materials used were purchased from Shanghai Titan Technology Co., Ltd.

[0033] Auxiliary equipment: constant pressure injection pump (pressure range 0-0.5MPa), electronic balance (accuracy 0.01g), stopwatch, 50mL beaker, iron stand, glass rod.

[0034] 2. Specific operating steps Step 1: Assembly of the apparatus. Vertically fix the 50mL glass chromatography column on the iron stand, fill the inner side of the lower end with a cut medical absorbent cotton disc, and gently press it down with a glass rod to a thickness of 1cm to form a uniform support filter layer.

[0035] Step 2: Simulated reservoir construction. Slowly add pretreated small glass beads into the chromatography column, gently tapping the column wall as you add them to ensure that the glass beads are evenly distributed without gaps or agglomerations. The final distribution height is 10 cm (occupying 2 / 5 of the effective volume of the chromatography column), thus constructing a simulated reservoir.

[0036] Step 3: Initial flow rate determination. Turn on the constant pressure injection pump and introduce deionized water into the chromatography column. Set the injection pressure to 0.1 MPa and continue injection for 30 minutes to stabilize the bed. Collect the deionized water flowing out within 1 minute using a drying beaker. Weigh it using an electronic balance to obtain 10.2 g. Based on a water density of 1 g / mL, the initial flow rate V0 = 10.2 mL / min.

[0037] Step 4: Gel particle injection and plugging. Switch the injection pipeline to a 1% concentration gel particle suspension, keep the injection pressure constant at 0.1 MPa, inject the suspension until the liquid level is flush with the upper surface of the glass bead layer, stop the injection and let it stand for 2 hours to allow the gel particles to be fully adsorbed and retained in the simulated reservoir pores.

[0038] Step 5: Flow rate measurement after plugging. Switch the injection line to deionized water, inject at a constant pressure of 0.1 MPa for 30 minutes until it stabilizes, collect the deionized water flowing out within 1 minute, weigh it to get 1.8 g, and calculate the flow rate after plugging as V1 = 1.8 mL / min.

[0039] Step 6: Evaluation of plugging performance. The plugging rate η was calculated using the formula η = (10.2 - 1.8) / 10.2 × 100% ≈ 82.4%, indicating that the acrylamide gel particles have a good plugging effect.

[0040] 3. Repeatability verification Three parallel experiments were conducted under the same conditions as described above, and the test data are shown in Table 1 below.

[0041]

[0042] The data shows that the blocking rate error of the three parallel experiments is ≤±2%, indicating that the test method of the present invention has good repeatability and stability.

[0043] Example 2: Performance Testing of Modified Starch Gel Particles Based on Acid Burettes for Blocking 1. Testing Materials and Apparatus The main testing apparatus consists of a 25mL acid burette (inner diameter 1.0cm, effective height 30cm) with a controllable flow rate valve at the lower end.

[0044] Support for the filter assembly: Medical absorbent cotton, cut into 1.0cm diameter circles, with a filling thickness of 0.8cm and a compacted density of 0.35g / cm³. 3 .

[0045] Simulated reservoir components: small glass beads (0.5-1mm in diameter), which are washed and dried with deionized water and then laid up to a height of 10cm (occupying 1 / 3 of the effective volume).

[0046] Test reagents: Modified starch-based gel particles (particle size 30-80 μm), prepared as a 1% (mass fraction) suspension (30 mL). These modified starch-based gel particles were developed in-house, using carboxymethyl starch as the base material and sodium trimetaphosphate as the crosslinking agent. The preparation method employed a reverse-phase suspension method. Carboxymethyl starch was dissolved in deionized water to prepare a starch slurry (8 wt%) as the aqueous phase. The pH of the aqueous phase was adjusted to 10.0 ± 0.2. The starch slurry was then added dropwise to a white oil phase containing Span 80 (5 wt% of oil phase) emulsifying stabilizer (water / oil phase volume ratio 1:4). A crosslinking agent (0.5 wt% of aqueous phase) was added, and the mixture was stirred at 350 rpm for 3 hours at 50°C for crosslinking reaction. The mixture was then aged at 50°C for 1 hour. The reaction product was washed alternately with ethanol and deionized water, dried at 60°C for 12 hours, ground, and sieved to obtain the final product. All materials used were purchased from Shanghai Titan Technology Co., Ltd.

[0047] Auxiliary equipment: constant pressure injection pump (pressure range 0-0.5MPa), electronic balance (accuracy 0.01g), stopwatch, 50mL beaker, iron stand, glass rod.

[0048] 2. Specific operating steps Step 1: Apparatus Assembly. Vertically fix the 25mL acid burette on the iron stand, fill the inner side of the lower end with a cut medical absorbent cotton disc, and gently press it down with a glass rod to a thickness of 0.8cm to form a uniformly supportive filter layer.

[0049] Step 2: Simulated reservoir construction. Slowly add pretreated small glass beads into the chromatography column, gently tapping the column wall as you add them to ensure that the glass beads are evenly distributed without gaps or agglomerations. The final distribution height is 10 cm (1 / 3 of the effective volume of the chromatography column), thus constructing a simulated reservoir.

[0050] Step 3: Initial flow rate determination. Turn on the constant pressure injection pump and introduce deionized water into the chromatography column. Set the injection pressure to 0.08 MPa and continue injection for 40 minutes to stabilize the bed. Collect the deionized water flowing out within 1 minute using a drying beaker, weigh it with an electronic balance to obtain 6.5 g, and convert it to a water density of 1 g / mL. The initial flow rate V0 = 6.5 mL / min.

[0051] Step 4: Gel particle injection and plugging. Switch the injection pipeline to a 1% concentration gel particle suspension, keep the injection pressure constant at 0.08 MPa, inject the suspension until the liquid level is flush with the upper surface of the glass bead layer, stop the injection and let it stand for 3 hours to allow the gel particles to be fully adsorbed and retained in the simulated reservoir pores.

[0052] Step 5: Flow rate measurement after plugging. Switch the injection line to deionized water, inject at a constant pressure of 0.08 MPa for 30 minutes until it stabilizes, collect the deionized water flowing out within 1 minute, weigh it to get 1.2 g, and calculate the flow rate after plugging as V1 = 1.2 mL / min.

[0053] Step 6: Evaluation of plugging performance. The plugging rate η was calculated using the formula η = (6.5 - 1.2) / 6.5 × 100% ≈ 81.5%, indicating that the modified starch gel particles have good plugging performance.

Claims

1. A method for testing the blocking performance of gel particles, characterized in that: The apparatus used in the test method includes a test body, a supporting filter layer, a simulated reservoir, and a constant pressure injection pump; The test body is a chromatography column or an acid burette; The lower end of the test body is filled with a support filter layer; glass beads are laid on the support filter layer as a simulated reservoir. The upper port of the test body is connected to a constant pressure injection pump via an injection pipeline; The testing method includes the following steps: (1) Turn on the constant pressure injection pump, inject water into the simulated reservoir, and measure the injection flow rate V0 after stabilization; (2) Inject a suspension of gel particles into the simulated reservoir and keep the injection pressure constant. After injecting the suspension of gel particles until the liquid surface is flush with the upper surface of the glass bead layer in the simulated reservoir, stop the injection and let it stand so that the gel particles can be fully adsorbed and retained in the pores of the simulated reservoir. (3) Inject water into the simulated reservoir and measure the injection flow rate V1 after stabilization; (4) Calculate the difference in water flow rate before and after injection of the gel particle suspension to quantify the sealing performance of the gel particles.

2. The test method according to claim 1, characterized in that: The test body is equipped with a controllable flow rate valve outlet at its lower end; The volume of the test subject is 20-100mL; The supporting filter layer is cotton; The glass beads have a particle size of 0.5-5mm and are laid up to a height of 1 / 3-1 / 2 of the effective volume of the test body.

3. The test method according to claim 2, characterized in that: The cotton used is medical-grade absorbent cotton, with a filling thickness of 0.5-2 cm and a compaction density of 0.3-0.6 g / cm³ after filling. 3 .

4. The test method according to claim 1, characterized in that: In step (1), the water injection flow rate V0 is measured after the water has stabilized for 30-60 minutes.

5. The test method according to claim 1, characterized in that: In step (2), the settling time is 2-4 hours.

6. The test method according to claim 1, characterized in that: In step (2), the mass percentage concentration of the gel particle suspension is 0.1%-5%; The gel particle suspension is injected under constant pressure, with an injection pressure of 0.05-0.5 MPa.

7. The test method according to claim 1, characterized in that: The water injection flow rate V0 and V1 are determined by "collecting the mass of outflowing liquid per unit time + water density conversion", and the liquid collection time is 1-5 minutes.

8. The test method according to claim 1, characterized in that: In step (1), the injected water is injected under constant pressure, with an injection pressure of 0.05-0.5 MPa.

9. The test method according to claim 1, characterized in that: In step (3), the injected water is injected under constant pressure, with an injection pressure of 0.05-0.5 MPa.

10. The test method according to claim 1, characterized in that: In step (4), the formula for calculating the blocking performance of the gel particles is as follows: η = (V0 - V1) / V0 × 100%; Where η is the plugging rate; V0 is the initial flow velocity in mL / min; and V1 is the flow velocity after plugging in mL / min.

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