High-temperature-resistant high-density hydrogel temporary plugging particle and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant high-density saline water-absorbing gel temporary plugging particle and a preparation method thereof, and belongs to the technical field of oilfield chemistry. The high-temperature-resistant high-density saline water-absorbing gel temporary plugging particle can resist the high temperature of 160 DEG C and can absorb high-density potassium formate water with the concentration of 1.55 g / cm < 3 >. The preparation process of one part of gel temporary plugging particle comprises the following components in percentage by mass: 5wt%-15wt% of sodium lignin sulfonate (relative to acrylic acid, the same below), 1wt%-8wt% of sepiolite, 1wt%-5wt% of a cross-linking agent 1, 0.2 wt%-6wt% of a cross-linking agent 2, a certain mass of acrylic acid (with the neutralization degree of 65%-90%), 30wt%-75wt% of a temperature-resistant monomer, 10wt%-25wt% of acrylamide and 0.5 wt%-1wt% of an initiator. The high-temperature-resistant gel temporary plugging particle disclosed by the invention has relatively high saline water absorption performance and temperature resistance, can absorb 35g / g of potassium formate water with the concentration of 1.55 g / cm < 3 >, has the solid phase mass of more than 85% after being aged at 160 DEG C for 3 days, and has excellent performance of high density and temperature resistance at 160 DEG C compared with conventional gel temporary plugging.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and particularly relates to high-temperature resistant high-density saltwater-absorbing gel temporary plugging particles and a preparation method thereof. Background Art

[0002] High-temperature resistant, high-density pre-crosslinked temporary plugging particles are currently a research hotspot. They not only have good pressure bearing and loss reduction capabilities, but also can avoid the problems of conventional in-situ cross-linked polymer gels damaging the reservoir and making it difficult to return water. Therefore, they can increase the success rate of perforation temporary plugging under the condition of low fluid loss of completion fluid. Gel temporary plugging fluid technology can isolate the producing layer from the upper well killing fluid, ensure well control safety and reduce formation damage caused by leakage. The current conventional system has a brine absorption capacity of 1.10g / cm 3 , it is difficult to further swell in the presence of high-density brine, and therefore cannot be used for temporary plugging in high-pressure coefficient reservoirs. In addition, the upper temperature limit of the existing gel temporary plugging particles is 120°C. When aged at high temperatures, they are decomposed and it is difficult to maintain the solid phase morphology and mechanical properties, which can easily cause temporary plugging failure. It is necessary to construct a high-temperature resistant 160°C and 1.55g / cm2 adsorption capacity from the perspective of molecular design and chemical synthesis. 3 The gel temporarily blocks the particles. Summary of the Invention

[0003] In order to solve at least one of the above problems, the present invention provides a high-temperature resistant high-density salt water absorbing gel temporary plugging particle, which has good high temperature resistance and salt water absorbing performance.

[0004] The present invention provides a high-temperature resistant high-density saltwater absorbing gel temporary plugging particle preparation material, which mainly includes sodium lignin sulfonate, sepiolite, a crosslinking agent 1, a crosslinking agent 2, acrylic acid, a temperature-resistant monomer, acrylamide and an initiator.

[0005] The technical solution for high-temperature-resistant, high-density, saltwater-absorbing gel temporary plugging particles is as follows: A certain amount of sodium lignin sulfonate and an appropriate amount of distilled water are added to a flask to dissolve the sodium lignin sulfonate. Then, sepiolite and polyethyleneimine (PEI) are added while stirring and heated to 60°C while stirring. A certain amount of deionized water is added to a beaker, an initiator is added, and stirred until dissolved. This initiator is then poured into the upper flask for activation. A certain amount of deionized water is added to a clean beaker, sodium hydroxide is added, and stirred in an ice-water bath until completely dissolved to obtain a sodium hydroxide solution. A certain amount of acrylic acid is weighed and added dropwise to the sodium hydroxide solution using a dropper to achieve the desired neutralization degree. Then, a certain amount of a temperature-resistant monomer, acrylamide, and a crosslinker 2 are weighed in sequence into a beaker, a certain amount of deionized water is added, and stirring is performed until completely dissolved to obtain a composite solution. Finally, the acrylic acid solution and the composite solution are added to the activation solution and heated to 70°C while stirring for 3 hours. After the reaction is complete, the gel in the flask is removed, shredded, and rinsed with deionized water at least three times to remove unreacted monomer. The cleaned gel is placed in a constant temperature oven at 85°C for 12 hours, and finally ground into 40-60 meshes to obtain the desired high-temperature resistant high-density salt water absorbing gel temporary plugging particles.

[0006] Notes: ① To allow the reaction system to communicate with the outside world, remove nitrogen, and retain low-boiling-point reactants, install a reflux condenser on the flask. ② To increase reaction rate and yield, use a stirrer to stir the solution thoroughly to ensure uniform concentration throughout the reaction. ③ To prevent the reactants from being oxidized by oxygen in the air, maintain a constant flow of nitrogen throughout the reaction.

[0007] For the above-mentioned sodium lignin sulfonate, the sodium lignin sulfonate in the preparation material of the gel temporary plugging particles has a small molecular weight, high solubility, and strong hydrophilicity. When it is grafted and pre-crosslinked with the temporary plugging gel molecular chain, the hydrophilicity of the molecule can be significantly improved, and the rate of absorption of salt water by the pre-crosslinked particles can be increased. At the same time, due to its low molecular weight properties, it will not be affected by the ionic strength in high-density salt water and affect the molecular extension morphology.

[0008] Mixing the aforementioned sepiolite with gel temporary plugging particles significantly increases its porosity and surface area, thereby increasing the contact area between the gel temporary plugging particles and brine, thereby increasing the rate and quality of brine absorption. Furthermore, the sepiolite's O-Si bonds form hydrogen bonds with the amino groups (NH2-) on the polymer chain, increasing the strength of the particles after absorbing brine and swelling.

[0009] For the crosslinking agent 1 mentioned above, it can react with the carboxyl group (-COOH) or carboxylic acid group (-CO - ) cross-linking, effectively increasing the cross-linking degree of the polymer and increasing the mechanical strength of the particles after swelling with salt water.

[0010] For the neutralized acrylic acid mentioned above, after polymerization, it can increase the affinity of the polymer network for water and the fixed charge. According to Flory's water absorption law, when the gel temporary plugging particles come into contact with high-density brine, the increase in the fixed charge inside the unexpanded gel network structure can enhance the brine absorption performance.

[0011] For the above-mentioned temperature-resistant monomers and acrylamide, after polymerization and addition into the polymer network, the temperature resistance and structural strength of the molecular chains of the network structure can be improved. At the same time, both monomers are hydrophilic monomers, which can improve the hydrophilicity of the gel temporary plugging particles, thereby improving the salt water absorption rate and quality of the gel temporary plugging particles.

[0012] For the above crosslinking agent 2, during the crosslinking process, it is crosslinked with different monomer polymer chains so that different single molecular chains form a unified three-dimensional network structure, so that the gel temporary blocking particles absorb moisture into the network structure but will not dissolve in water.

[0013] In particular, the inventors discovered that using only Crosslinker 1 or Crosslinker 2 resulted in low mechanical strength in the post-polymerization gel. Furthermore, if the crosslinker concentration was below a given value, the crosslinking reaction was incomplete, causing the cured gel to flow slowly when inverted for extended periods. Furthermore, such gels dissolve during washing. Furthermore, they struggled to maintain their particle shape after drying.

[0014] One embodiment of the present invention is that the high temperature resistant high density saline gel temporary plugging particles can absorb a density of 1.55g / cm 3 After aging for 3 days at 160℃, the quality of the solid particles can be preserved by more than 85%.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The high-temperature-resistant, high-density saltwater-absorbing gel temporary plugging particles of the present invention have good high-temperature resistance. After aging at 160°C for 3 days, the solid-phase particle mass is retained by more than 85%. They also have high high-density saltwater absorption performance. Compared with conventional gel temporary plugging particles, they can be used for temporary plugging operations at a formation pressure coefficient of 1.55 and a temperature of 160°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Example 1 High temperature resistant high density saline water absorption gel temporary plugging particles saline water absorption performance diagram;

[0018] Figure 2 Example 1 High temperature resistant absorption high density salt water gel temporary plugging particles temperature resistance performance diagram;

[0019] Figure 3 Example 3: Performance diagram of high-temperature resistant high-density saline water gel temporary plugging particles absorbing saline water;

[0020] Figure 4 Example 3: Temperature resistance performance diagram of high-temperature resistant high-density salt water gel temporary plugging particles;

[0021] Figure 5 Example 4: Performance diagram of high-temperature resistant high-density saline water gel temporary plugging particles absorbing saline water;

[0022] Figure 6 Example 4: Temperature resistance performance diagram of high-temperature resistant high-density saltwater gel temporary plugging particles; DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0024] In the following examples, unless otherwise specified, the raw materials used are conventional commercial products.

[0025] In the following examples, unless otherwise specified, the methods used are conventional methods in the art.

[0026] In the following examples, the following methods were used to measure the salt water absorption performance and high temperature resistance:

[0027] The natural filtration method was chosen for its ease of implementation and simplicity. A certain amount of product was weighed and placed in a beaker. An excess of high-density saline was then added to the beaker. After a period of time, the product absorbed all of the liquid.

[0028] Pour the mixture in the beaker into a 120-mesh sieve and let it sit for 30 minutes. Finally, weigh the filtered gel using an electronic balance and calculate the gel's liquid absorption performance using the following formula.

[0029] Q s =(M1-M0) / M0

[0030] Where:

[0031] Q s ———Brine solution absorption rate, g / g. The larger the rate, the better the salt solution absorption performance;

[0032] M1——The mass of gel temporary blocking particles when they completely absorb salt solution, g;

[0033] M0——dry weight of gel temporary plugging particles, g;

[0034] In the following examples, the temperature resistance was measured using the following method:

[0035] The saturated gel temporary plugging particles are filtered and weighed, and the solid phase mass is recorded as m0. Then the gel temporary plugging particles are mixed with high-density brine and poured into an aging tank. The aging tank is placed in a high-temperature constant temperature oven for aging. The aging tank is opened every other day and filtered and re-weighed, which are recorded as m1, m2...m i The mass retention rate of the gel temporary plugging particles was calculated by the following formula to evaluate its temperature resistance:

[0036] F=m i / m0*100%

[0037] Among them, F represents the mass retention rate of the gel temporary plugging particles after aging, with a maximum value of 100%. For the same aging time, the larger the F value, the better the temperature resistance of the gel temporary plugging particles.

[0038] Example 1

[0039] Dissolve 1g of sodium lignin sulfonate, 0.5g of sepiolite, and 0.5g of polyethylene terephthalate (PEI) in 5ml of deionized water to obtain Mixture 1. Dissolve 0.1g of potassium persulfate in 5ml of deionized water to obtain an initiator solution. Dissolve 3.64g of sodium hydroxide in 10ml of deionized water, then add 10g of acrylic acid dropwise to obtain a neutralized acrylic acid solution. Dissolve 7.5g of a heat-resistant monomer and 2.5g of acrylamide in 10ml of deionized water, then add 0.05g of Crosslinker 2 to obtain Mixture 2. High-temperature-resistant, high-density, saline-absorbing gel temporary plugging particles were prepared through the above experimental steps.

[0040] It was found that its 3-day salt water absorption capacity could reach 35.5g / g. Figure 1 As shown, after aging at 160 ° C for 3 days, the mass retention rate of the gel temporary plugging particles reached 85%, as shown in Figure 2 shown.

[0041] Example 2 No crosslinking agent 1 was added

[0042] Dissolve 1g of sodium lignin sulfonate and 0.5g of sepiolite in 5ml of deionized water to obtain Mixture 1. Dissolve 0.1g of potassium persulfate in 5ml of deionized water to obtain an initiator solution. Dissolve 3.64g of sodium hydroxide in 10ml of deionized water, then add 10g of acrylic acid dropwise to obtain a neutralized acrylic acid solution. Dissolve 7.5g of a heat-resistant monomer and 2.5g of acrylamide in 10ml of deionized water, then add 0.05g of Crosslinker 2 to obtain Mixture 2. High-temperature-resistant, high-density, saltwater-absorbing gel temporary plugging particles were prepared through the above experimental steps.

[0043] During the salt water absorption test, the gel temporary plugging particles gradually dissolved into the salt water, and the solid phase particles completely disappeared after aging at 160°C for 3 days.

[0044] Example 3 Increase the mass fraction of sodium lignin sulfonate

[0045] Dissolve 1.5g of sodium lignin sulfonate, 0.5g of sepiolite, and 0.5g of polyethylene terephthalate (PEI) in 5ml of deionized water to obtain Mixture 1. Dissolve 0.1g of potassium persulfate in 5ml of deionized water to obtain an initiator solution. Dissolve 3.64g of sodium hydroxide in 10ml of deionized water, then add 10g of acrylic acid dropwise to obtain a neutralized acrylic acid solution. Dissolve 7.5g of a heat-resistant monomer and 2.5g of acrylamide in 10ml of deionized water, then add 0.05g of Crosslinker 2 to obtain Mixture 2. High-temperature-resistant, high-density, saline-absorbing gel temporary plugging particles were prepared through the above experimental steps.

[0046] It was found that its salt water absorption capacity in 3 days could reach 30.2g / g. Figure 3 As shown in Figure 2, the mass retention rate of the gel temporary plugging particles after aging at 160°C for 3 days reached 82.5%. Figure 4 shown.

[0047] Example 4 changes the mass fraction of cross-linking agent 2

[0048] Dissolve 1g of sodium lignin sulfonate, 0.5g of sepiolite, and 0.5g of polyethylene terephthalate (PEI) in 5ml of deionized water to obtain Mixture 1. Dissolve 0.1g of potassium persulfate in 5ml of deionized water to obtain an initiator solution. Dissolve 3.64g of sodium hydroxide in 10ml of deionized water, then add 10g of acrylic acid dropwise to obtain a neutralized acrylic acid solution. Dissolve 7.5g of a heat-resistant monomer and 2.5g of acrylamide in 10ml of deionized water, then add 0.1g of Crosslinker 2 to obtain Mixture 2. High-temperature-resistant, high-density, saline-absorbing gel temporary plugging particles were prepared through the above experimental steps.

[0049] It was found that its 3-day salt water absorption capacity could reach 25.1 g / g. Figure 5 As shown in Figure 2, the mass retention rate of the gel temporary plugging particles after aging at 160°C for 3 days reached 89.3%. Figure 6 shown.

[0050] In summary, the high-temperature resistant high-density saltwater absorbing gel temporary plugging particles of the embodiment of the present invention have good high-density saltwater absorbing performance, can withstand high temperatures of 160°C, and can meet the needs of actual well repair operations. At the same time, its cost is relatively low, and it is suitable for large-scale promotion. Although the embodiment of the present invention only lists the example of high-temperature resistant high-density saltwater absorbing temporary plugging particles at a temperature of 160°C, those skilled in the art know that for high-temperature temporary plugging fluids, the higher the temperature, the faster the degradation rate of the gel temporary plugging particles, and ultimately the faster the temporary plugging failure problem. The high-temperature resistant high-density saltwater absorbing gel temporary plugging particles of the embodiment of the present invention have good temperature resistance when the temperature is 160°C. Then, when the temperature is lower, those skilled in the art can also infer that it also has good technical effects. In addition, the present invention only lists the gel temporary plugging particles with an absorption density of 1.55g / cm 3 For example, potassium formate brine is used. However, those skilled in the art know that for gel temporary plugging particles, the higher the concentration of brine absorbed, the greater the density of brine, the lower the water absorption quality, and eventually the particles will not even absorb brine to expand. However, the high temperature resistant high density brine absorbing gel temporary plugging particles of the embodiment of the present invention, when the density of the absorbed brine is 1.55 g / cm 3 If it has a good effect when the density of the absorbed brine is lower, those skilled in the art can also infer that it also has a good technical effect.

[0051] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A high-temperature resistant high-density saltwater gel temporary plugging particle and a preparation method thereof, characterized in that: In terms of mass percentage, the preparation process of a portion of the gel temporary plugging particles includes 5wt% to 15wt% of sodium lignin sulfonate (relative to the mass of acrylic acid, the same below), 1wt% to 8wt% of sepiolite, 1wt% to 5wt% of cross-linking agent 1, wherein the cross-linking agent 1 is a combination of one or more of polyethyleneimine (PEI), chromium acetate, zinc acetate, and aluminum chloride, 0.2 to 6wt% of cross-linking agent 2, wherein the cross-linking agent 2 is N,N-methylenebisacrylamide (MBA), a certain mass of acrylic acid (neutralized by sodium hydroxide with a neutralization degree of 65% to 90%), 30wt% to 75wt% of a temperature-resistant monomer, wherein the temperature-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 10wt% to 25wt% of acrylamide, and 0.5wt% to 1wt% of an initiator, wherein the initiator is a combination of one or more of potassium persulfate (KPS) and ammonium persulfate (APS).

2. The high temperature resistant high density salt water absorbing gel temporary plugging particles and the preparation method thereof according to claim 1, characterized in that: In terms of mass percentage, the concentration of the cross-linking agent 1 is 1 wt % to 5 wt %.

3. The high temperature resistant high density salt water gel temporary plugging particles according to claim 1, characterized in that: The cross-linking agent 1 is a combination of one or more of polyethyleneimine (PEI), chromium acetate, zinc acetate, and aluminum chloride.

4. The high temperature resistant high density salt water absorbing gel temporary plugging particles according to claim 1, characterized in that: The cross-linking agent 2 is N,N-methylenebisacrylamide (MBA).

5. The high temperature resistant high density salt water absorbing gel temporary plugging particles and the preparation method thereof according to claim 1, characterized in that: The initiator is one or more combinations of potassium persulfate (KPS) and ammonium persulfate (APS).

6. The high temperature resistant high density salt water gel temporary plugging particles according to claim 1, characterized in that: The cross-linking agent is a compound of cross-linking agent 1 and cross-linking agent 2.

Images