Multifunctional filling particle for sand prevention and yield increase of hydrate reservoir as well as preparation method and application of multifunctional filling particle
By constructing a composite functional coating on the surface of the filling particles, the problem of sand prevention and production enhancement in hydrate reservoirs in low-temperature shallow soft formations has been solved, achieving efficient sand prevention, stable flow guidance and inhibition of mud and sand accumulation, thereby improving the safety and economy of mining.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGZHOU NANSHADI BINHAI RESEARCH INSTITUTE
- Filing Date
- 2025-12-12
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies struggle to produce multifunctional integrated materials that are efficient in filling, provide long-term sand control, stabilize flow, and inhibit mud and sand accumulation under low-temperature and shallow soft strata conditions. This leads to problems such as sand production, mud and sand migration and accumulation during hydrate reservoir exploitation, affecting the safety and economy of the exploitation process.
A composite functional coating is constructed on the surface of filling particles using a hybrid coating technology of anionic polymer and fluoropolymer. This enhances hydrophobicity and negative charge, and inhibits the aggregation of mud and sand through electrostatic repulsion, thereby promoting efficient fluid flow.
It significantly improves the hydrophobicity and surface negative charge of the filling particles, prevents mud and sand from accumulating and clogging, promotes fluid production, and improves the permeability and extraction efficiency of hydrate reservoirs. It is suitable for large-scale preparation and is environmentally friendly and safe.
Smart Images
Figure CN122037899A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of natural gas hydrate extraction technology, and in particular to a multifunctional filling particle for sand control and production enhancement in hydrate reservoirs, its preparation method, and its application. Background Technology
[0002] Commercial exploitation of natural gas hydrates still faces a series of severe technical challenges. Survey data shows that more than 80% of global natural gas hydrate resources are found in silty mudstone reservoirs. These reservoirs have geological characteristics such as loose structure, weak consolidation, and low bearing capacity. During the exploitation process, especially after the decomposition of hydrates, the cementing effect of the original solid hydrates on the sediments disappears, which can easily lead to problems such as formation sand production, mud and sand migration and accumulation. Specifically, this manifests as: (1) poor gas / water flow channels, rapid flow decay, and short stable production cycle; (2) mud and sand particles migrate with the fluid, blocking formation pores and downhole sand control media, which seriously affects the safety and economy of exploitation.
[0003] To address these challenges and improve extraction efficiency, the industry has widely adopted and modified production enhancement technologies used in conventional oil and gas extraction. Among these, the method of filling the near-wellbore zone with highly permeable particles (such as gravel) to construct artificial sand barriers has proven effective in enhancing the structural stability of the wellbore area and improving reservoir permeability, thus achieving good results in conventional oil and gas field development. However, directly applying this technology to natural gas hydrate reservoirs, especially shallow, low-fracture-pressure silty clay reservoirs, has encountered significant bottlenecks: Currently, most functional coated proppant particles (coated sand) developed in the oil and gas industry have only one function, focusing either on improving strength, altering wettability, or being limited by reaction temperature. There is a lack of a multifunctional integrated material that can simultaneously achieve efficient filling, long-term sand control, stable flow conduction, and inhibition of mud and sand accumulation under low-temperature, shallow, and soft formation conditions. This makes it difficult for existing technologies to meet the complex requirements of safe and efficient filling and sand control in long horizontal sections of hydrate reservoirs. Summary of the Invention
[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a multifunctional filling particle for sand control and production enhancement in hydrate reservoirs, its preparation method, and its application.
[0005] The first objective of this invention is to provide a method for preparing multifunctional filling particles for sand control and production enhancement in hydrate reservoirs, comprising the following steps: S1. A certain amount of anionic polymer X is fully dissolved in water, and then a solution or emulsion of fluoropolymer Y is added. After mixing evenly, the coating solution is obtained.
[0006] S2. Pour the initial filling particles into the coating liquid and stir for a certain period of time to obtain surface-modified multifunctional filling particles.
[0007] S3. Wash, filter, and dry the multifunctional filling particles to obtain the multifunctional filling particles.
[0008] Furthermore, in the coating solution, the mass ratio of the anionic polymer X to the fluoropolymer Y is 1:2-50.
[0009] Furthermore, the filling particles are lightweight ceramic particles.
[0010] Furthermore, the anionic polymer X is one or more of polymethylcellulose salt, alginate, lignin sulfonate, polyacrylate, polymethacrylate, polycarboxylate, polystyrene sulfonate, and anionic polyacrylamide.
[0011] Furthermore, in the coating solution, the concentration of the anionic polymer X is 0.5~50 g / L.
[0012] Furthermore, the fluoropolymer Y is one or more of polyvinylidene fluoride, polytetrafluoroethylene, and perfluoroethylene propylene.
[0013] Furthermore, the solid content of the solution or emulsion of the fluoropolymer Y is 10% to 60%.
[0014] Furthermore, the mass ratio of the sum of the anionic polymer X and the fluoropolymer Y to the mass of the filling particles is 1:30-100.
[0015] Furthermore, in step S2, the stirring time is 20-40 hours, and the stirring temperature is 10-30°C. Preferably, mechanical stirring is used, and the stirring temperature is 20°C.
[0016] Furthermore, in step S3, the washing cycle is 3-5 times, and the detergent is deionized water. The drying temperature is 40-60℃, and the drying time is 24-48 hours.
[0017] A multifunctional filling particle for sand control and production enhancement in hydrate reservoirs, prepared using the above-described preparation method.
[0018] Application of a multifunctional filling particle for sand control and production enhancement in hydrate reservoirs, as described above, in the exploitation of hydrate geological energy reservoirs.
[0019] This invention provides a multifunctional filling particle for sand control and production enhancement in hydrate reservoirs. A composite functional coating is constructed on the surface of the filling particle using solution coating technology. The surface of the filling particle has various polar groups such as hydroxyl and carboxyl groups, which can interact with the polar functional groups of fluorinated polymers and anionic polymers. A mixed coating solution is prepared from two polymers with different polarities. During a dynamic process of thorough stirring, the fluorinated polymer and anionic polymer chains slowly and uniformly settle onto the surface of the filling particle through electrostatic interaction, achieving uniform adhesion of functional components to the particle surface and thus achieving physical modification. This significantly improves the hydrophobicity and surface negative charge of the filling particle. The fluorinated polymer, due to its extremely low surface free energy, effectively enhances hydrophobicity, while the anionic polymer, after dissociation in the aqueous phase, imparts a stable negative charge to the particle surface, inhibiting the adsorption and aggregation of clay-containing particles through electrostatic repulsion.
[0020] This invention addresses the unique geological conditions of hydrate reservoirs by modifying the surface function of filling particles. The resulting invention and products can be applied to drilling, completion, and production enhancement operations in various geological and energy reservoirs, including hydrate reservoirs. The modified filling particles will promote the efficient flow and production of formation water and gas during drilling and production, while simultaneously preventing the migration, loss, and accumulation of solid components such as formation mud and sand, thus serving the safe, efficient, and sustainable development of various geological and energy reservoirs. This invention has significant theoretical guidance and practical application value.
[0021] Compared with existing technical solutions, it has the following advantages: 1. This invention prepares a coating liquid by directly mixing fluoropolymers and anionic polymers, achieving in-situ direct coating of the filling particles with a hydrophobic and negatively charged multifunctional material. The modified filling particles can reduce liquid adsorption on the particle surface, effectively promote fluid production, enhance the repulsive effect on the particle surface, and effectively prevent the accumulation and blockage of mud and sand.
[0022] 2. The raw materials used in this preparation process are all common industrial products, which have a cost advantage and are suitable for mass production; moreover, the process is simple, fast, stable and efficient, and the aqueous preparation conditions are safe and environmentally friendly. Attached Figure Description
[0023] Figure 1 This is a flowchart of the preparation method of the present invention; Figure 2 Scanning electron microscope images of the entirety and surface of the initial filling particles in the control example; Figure 3 The images show scanning electron microscope images of the entire multifunctional filling particle E prepared in Example 5 and its surface. Figure 4 Photographs showing the water contact angle test of the initial filling particles in the control example; Figure 5 Photographs showing the water contact angle of the multifunctional filling particles E prepared in Example 5; Figure 6 Photographs showing the water contact angle of the multifunctional filling particles F prepared in Example 6; Figure 7 The bar chart shows the surface negative charge test results of the initial filling particles in the control example and the multifunctional filling particles E prepared in Example 5. Figure 8 The permeability test curves are for the initial filling particles in the control example and the multifunctional filling particles E prepared in Example 5. Figure 9 and Figure 10 This is a graph showing the solid-phase particle size distribution of the initial filling particles and the multifunctional filling particles E. Detailed Implementation
[0024] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.
[0025] The filling particles used in the following examples are recycled polystyrene resin particles, purchased from Beijing Qixiangtao Co., Ltd.
[0026] Example 1: Weigh 1 g of sodium polymethyl cellulose and 9 g of polyvinylidene fluoride emulsion with a solid content of 25%, and dissolve them in 150 ml of water to prepare a coating solution. Then weigh out filling particles with a mass ratio of 1:3 to the total polymer. Pour the weighed filling particles into the coating solution and mechanically stir for 48 h at 25°C. Transfer the coated multifunctional filling particles A to a Buchner funnel and wash them three times using deionized water via vacuum filtration. After completing the above steps, transfer them to a glass dish to dry at 40°C for 48 h.
[0027] Example 2: Weigh 0.06 g of sodium polymethyl cellulose and 3 g of 50% solids content poly(fluoroethylene propylene) emulsion, and dissolve them in 100 ml of water to prepare a coating solution. Then weigh out filling particles with a mass ratio of 1:10 to the total polymer. Pour the weighed filling particles into the coating solution and mechanically stir for 48 h at 25°C. Transfer the coated multifunctional filling particles B to a Buchner funnel and wash them three times using deionized water via vacuum filtration. After completing the above steps, transfer them to a glass dish to dry at 50°C for 36 h.
[0028] Example 3: Weigh 0.05 g of sodium polymethyl cellulose and 1 g of polytetrafluoroethylene (PTFE) with a solid content of 60%, and dissolve them in 100 ml of water to prepare a coating solution. Then weigh out filling particles with a mass ratio of 1:30 to the total polymer. Pour the weighed filling particles into the coating solution and mechanically stir for 48 h at 25°C. Transfer the coated multifunctional filling particles C to a Buchner funnel and wash them three times using deionized water via vacuum filtration. After completing the above steps, transfer them to a glass dish to dry at 60°C for 24 h.
[0029] Example 4: Weigh 0.05 g of sodium polystyrene sulfonate and 1 g of polytetrafluoroethylene emulsion with a solid content of 60%, and dissolve them in 100 ml of water to prepare a coating solution. Then weigh out filling particles with a mass ratio of 1:30 to the total polymer. Pour the weighed filling particles into the coating solution and mechanically stir for 48 h at 25°C. Transfer the coated multifunctional filling particles D to a Buchner funnel and wash them three times using deionized water via vacuum filtration. After completing the above steps, transfer them to a glass dish to dry at 50°C for 24 h.
[0030] Example 5: Weigh 0.5 g of sodium polystyrene sulfonate and 10 g of polytetrafluoroethylene emulsion with a solid content of 60%, and dissolve them in 1000 ml of water to prepare a coating solution. Then weigh out filling particles with a mass ratio of 1:30 to the total polymer. Pour the weighed filling particles into the coating solution and mechanically stir for 48 h at 25°C. Transfer the coated multifunctional filling particles E to a Buchner funnel and wash them three times using deionized water via vacuum filtration. After completing the above steps, transfer them to a glass dish to dry at 50°C for 24 h.
[0031] Example 6: Weigh 0.05 g of sodium polystyrene sulfonate and 1 g of polytetrafluoroethylene emulsion with a solid content of 60%, and dissolve them in 150 ml of water to prepare a coating solution. Then weigh out filling particles with a mass ratio of 1:100 to the total polymer. Pour the weighed filling particles into the coating solution and mechanically stir for 48 h at 25°C. Transfer the coated multifunctional filling particles F to a Buchner funnel and wash them three times using deionized water via vacuum filtration. After completing the above steps, transfer them to a glass dish to dry at 50°C for 24 h.
[0032] Example for comparison: The initial filling particles were directly subjected to contact angle, negative charge properties, permeability tests and other corresponding experiments.
[0033] Test method: Instructions for the contact angle test method: Attach a piece of double-sided tape about 5 cm long to a glass slide, apply a small amount of multi-functional filling particles to it, and repeat the process until the surface is uniform and flat. Then, use a contact angle tester to measure the contact angle.
[0034] Instructions for determining surface acid radicals using the laboratory ion exchange column method: Take an appropriate amount of multifunctional packing particles, soak them in hydrochloric acid for 48 hours, filter, and wash away excess acid. Soak the washed and dried packing particles in a certain amount of prepared NaCl solution for 48 hours to allow the NaCl to precipitate. + After a full exchange reaction with the acid on the surface coating, the solution is filtered, collected, and its pH is measured. The content of acid radicals can then be calculated.
[0035] Description of the surface negative charge test method: The tester is the VSI-USCA2001 general surface charge tester (Chongqing Weixun Scientific Instruments).
[0036] Instructions for the water immersion durability test: Take 2 g of initial filling particles into a 40 ml sample bottle, add 30 ml of deionized water, let stand in a cool place for 90 days, and observe the hydrophobicity of the particles on the water surface.
[0037] Instructions for the permeability testing method: Take 130 g of multifunctional filling granules and fill them into the latex membrane of the permeability testing chamber to prepare a sample with a diameter of 5 cm and a height of 10 cm. After applying a certain confining pressure (normal confining pressure is 1 MPa, low confining pressure is 0.2 MPa), fluid is introduced into one end of the sample until the fluid flows out steadily from the other end. Measure the pressure difference between the two ends of the sample at different fluid flow rates, and calculate the corresponding permeability using Darcy's law.
[0038] Table 1 shows the contact angle and negative charge test results of the initial filling particles in the examples and the modified filling particles in the control examples. It shows that the hydrophobicity and negative charge of the surface of the modified filling particles have been significantly improved, and the measured values are linearly related to the theoretical calculations. Table 1
[0039] Figure 1 This is a flowchart of the preparation method of the present invention; Figure 2 Scanning electron microscope images of the entire initial filling particles (left image) and the surface (right image) in the control example; Figure 3The images show scanning electron microscope (SEM) images of the entire multifunctional filling particle E prepared in Example 5 (left image) and its surface (right image). It can be clearly seen from the images that, compared with the initial filling particles, the surface of the multifunctional filling particle E prepared in this invention is covered with a layer of obvious granular and filamentous coating. Figure 4 The photograph shows the water contact angle of the initial filling particles in the control example, which is 124.3°. Figure 5 The image shows a water contact angle test of the multifunctional filling particle E prepared in Example 5, indicating a contact angle of 132.2° and an increase in contact angle of 7.9°. Figure 6 The image shows a water contact angle test of the multifunctional filling particle F prepared in Example 6, indicating a contact angle of 132.6° and an increase in contact angle of 8.3°. Figure 7 The bar charts show the surface negative charge test results for the initial filling particles in the control example and the multifunctional filling particles E prepared in Example 5. Under neutral pH=7 and weakly alkaline pH=8 conditions, the surface negative charge of the coated filling particles was increased compared to the initial filling particles. Furthermore, due to the greater dissociation of acidic groups under weakly alkaline conditions, the amount of surface negative charge was higher compared to the neutral conditions.
[0040] Figure 8 The permeability test curves are shown for the initial filling particles in the control example and the multifunctional filling particles E prepared in Example 5. Under different fluid flow rates, the modified and coated filling particles all have higher permeability.
[0041] Figure 9 and Figure 10 This figure shows the solid-phase production particle size data for the initial filling particles and the multifunctional filling particle E. By performing special surface treatment on the gravel, the physicochemical properties of the gravel surface are altered, thus endowing the sand-control gravel layer with the function of "sand control and mud removal". Seepage tests were conducted using composite formation mud and sand samples with the same particle size distribution. The figure shows that the proportion of clay components in the solid-phase production of the modified particles is significantly increased compared to the unmodified particles. The modified gravel layer not only effectively blocks coarse sand due to its geometric dimensions, but also inhibits the adsorption and bridging of fine particles through optimized surface interactions, allowing clay particles to pass smoothly in a dispersed state. This solves the industry problem of traditional technologies being unable to balance sand-control efficiency and system unobstructed flow.
[0042] For any points not covered above, existing technologies shall apply.
[0043] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing multifunctional filling particles for sand control and production enhancement in hydrate reservoirs, characterized in that, Includes the following steps: S1. A certain amount of anionic polymer X is fully dissolved in water and then a solution or emulsion of fluoropolymer Y is added. After mixing evenly, the coating solution is obtained. S2. Pour the filling particles into the coating liquid and stir to coat for a certain period of time to obtain surface-modified multifunctional filling particles. S3. Wash, filter, and dry the multifunctional filling particles to obtain the multifunctional filling particles.
2. The preparation method according to claim 1, characterized in that, The coating solution contains anionic polymer X and fluorinated polymer Y in a mass ratio of 1:2-50.
3. The preparation method according to claim 1, characterized in that, The filling particles are lightweight ceramic granules.
4. The preparation method according to claim 1, characterized in that, The anionic polymer X is one or more of polymethylcellulose salt, alginate, lignin sulfonate, polyacrylate, polymethyl methacrylate, polycarboxylate, polystyrene sulfonate, and anionic polyacrylamide.
5. The preparation method according to claim 3, characterized in that, In the coating solution, the concentration of the anionic polymer X is 0.5~50 g / L.
6. The preparation method according to claim 1, characterized in that, The fluoropolymer Y is one or more of polyvinylidene fluoride, polytetrafluoroethylene, and perfluoroethylene propylene.
7. The preparation method according to claim 5, characterized in that, The solid content of the solution or emulsion of the fluoropolymer Y is 10% to 60%.
8. The preparation method according to claim 1, characterized in that, The sum of the masses of anionic polymer X and fluorinated polymer Y is in a mass ratio of 1:30-100 to the mass of the filling particles.
9. A multifunctional filling particle for sand control and production enhancement in hydrate reservoirs, prepared by the preparation method according to any one of claims 1-8.
10. The application of the multifunctional filling particles for sand control and production enhancement in hydrate reservoirs as described in claim 9 in the exploitation of hydrate geological energy reservoirs.