Water blocking and channeling preventing temporary plugging system for pressure drive and application thereof

Abstract

The application discloses a water-retarding and channeling-preventing temporary plugging system for pressure flooding, which is composed of water-soluble fibers and soluble metal alloy particles, and the water-soluble fibers account for 5-15% in mass percentage; the soluble metal alloy particles account for 85-95% in mass percentage. The application also discloses application of the water-retarding and channeling-preventing temporary plugging system for pressure flooding in low-permeability oil reservoirs as a temporary plugging agent for pressure flooding.(1) The application has higher pressure difference resistance, stronger high-temperature resistance, stronger temperature and salt resistance, longer effective plugging time, and can better meet the needs of long-time pressure flooding operation; (2) In the process of water injection pressure flooding, the soluble metal alloy component gradually corrodes into powder particles with smaller particle size, the particles formed at the trailing edge of the plugging section can continuously embed into the gaps of the temporary plugging material, the powder particles formed at the leading edge of the plugging section can enter deep small cracks or branch cracks, so that the crack plugging is more dense, the plugging rate is higher, the plugging stability is stronger, and the plugging effect is further ensured.

Description

Technical Field

[0001] This invention relates to the fields of oilfield chemistry and oil and gas field development engineering technology, and in particular to a water suppression and anti-channeling temporary plugging system for pressure drive and its application. Background Technology

[0002] China has abundant low-permeability oil resources, but the reservoir conditions of low-permeability oil reservoirs are complex and difficult to develop. They are characterized by low permeability, high flow resistance, low production, rapid production decline, and slow energy replenishment.

[0003] To improve the exploitation effect of low-permeability oil reservoirs, it is usually necessary to take measures such as water injection to replenish formation energy. However, in the process of water injection development of low-permeability oil reservoirs, there are common problems such as high water injection pressure and high under-injection ratio. The contradiction of "inability to inject and inability to extract" is prominent. Effective displacement between oil and water wells cannot be established, formation energy declines rapidly, and production capacity decreases rapidly or even stops.

[0004] To address the aforementioned issues, oilfields have combined hydraulic fracturing with water injection to form a hydraulic fracturing and water injection technology. This technology can increase the pore throat radius, extend the seepage distance, and quickly and effectively replenish formation energy. It is a promising and effective method to solve the dilemma of injection and production in low-permeability reservoirs, resulting in low recovery rates and low oil production rates. For example, Chinese patent application CN 114439437A discloses a method for improving the recovery rate of low-permeability reservoirs through hydraulic fracturing. The method includes the following steps: during the water well injection pressure increase stage, determining the water well injection volume and injection time; during the water well shut-in pressure diffusion stage, determining the water well shut-in time; during the oil well production pressure decrease stage, determining the oil well shut-in production time; during the oil well shut-in pressure recovery stage, determining the oil well shut-in time; repeating the above steps for multiple rounds of cyclic production.

[0005] However, in the development of low-permeability reservoirs by pressure-driven water injection, the following problems exist: (1) It is difficult to turn the fractures, the lateral micro-fractures are poorly opened, the fractures are single, the pressure-driven sweep coefficient is low, resulting in low oil displacement efficiency; (2) The main fractures are prone to excessive extension, leading to pressure penetration, causing oil and water wells to penetrate, water to flow too early, and causing the oil wells to shut down.

[0006] To address the aforementioned issues, appropriate temporary plugging measures need to be taken to prevent excessive extension of the main crack during water injection and pressure driving, which could lead to crack isolation or water channeling.

[0007] Currently, there are various types of temporary plugging agents. Based on their morphology, they can be broadly classified into granular, fibrous, and rubber-based temporary plugging agents; based on their unblocking mechanism, they can be divided into water-soluble, acid-soluble, oil-soluble, and biodegradable temporary plugging agents. Among these:

[0008] Oil-soluble temporary plugging agents are generally made of materials such as resin and paraffin, and have a certain pressure resistance. However, they are thermoplastic and easily soften at high temperatures. They are usually only suitable for oil wells and not for water injection pressure drive operations. Although other types of temporary plugging agents can be used for water injection pressure drive, their performance in terms of temperature resistance, pressure resistance, dissolution, and plugging effect varies, and their application in pressure drive needs further improvement.

[0009] For example, Chinese patent application CN115850573A discloses a water-soluble particulate temporary plugging agent, which is composed of 15%–20% acrylamide, 1%–2% methyl acrylate, 0.5%–1% crosslinking agent, 0.15%–1.1% initiator, 2%–5% mutual solvent, 0.02%–0.03% co-solvent, and the balance being water. This temporary plugging agent requires a particle size of 140–210 mesh. If the particle size is too large, the plugging effect will be poor; if the particle size is too small, the plugging efficiency will be low, and the amount of temporary plugging agent used will increase, as well as the cost. It dissolves quickly in water, with a dissolution time of 15–20 minutes, resulting in a short plugging time, which cannot meet the requirements of pressure drive operations.

[0010] Chinese patent application CN115838589A discloses a gel-like particulate temporary plugging agent, comprising 4%–10% polyvinyl alcohol, 0.03%–0.05% aldehyde crosslinking agent, 0.2%–0.4% potential acid catalyst, and the balance being water. This temporary plugging agent exhibits low plugging strength, a plugging pressure of 6.03 MPa, and is suitable for temperatures of 90–120℃ and a salinity ≤4×10⁻⁶. 4 Formations with a concentration of mg / L cannot meet the pressure-bearing capacity requirements of pressure-driven processes.

[0011] Chinese patent application CN115895617A discloses a fiber-based temporary plugging agent, which is a water-soluble temporary plugging agent. This agent comprises a polyvinyl alcohol (PVA) fiber matrix and sodium silicate uniformly dispersed within the PVA fiber matrix; the mass of the sodium silicate is 25-35% of the total mass of the fiber-based temporary plugging agent. This fiber-based temporary plugging agent exhibits good unblocking effect at high temperatures of 140-160°C, with a dissolution time of 20.5-23.8 hours. Its dissolution conditions and effects are suitable for high-temperature reservoir fracturing. However, its breakthrough pressure is 10-18.7 MPa, which is insufficient to meet the pressure resistance and plugging aging requirements of hydraulic fracturing processes.

[0012] Chinese patent application CN109401739A discloses a high-temperature resistant shielding temporary plugging agent, which is an acid-soluble temporary plugging agent. The components, by weight, include 100 parts particulate material; 5-20 parts elastic material; 5-20 parts filler material; 5-15 parts fiber material; and 1-5 parts micro / nano material. This temporary plugging agent can withstand temperatures up to 200℃ and pressures greater than 10MPa. Its acid solubility in 15wt% hydrochloric acid is greater than 80%, demonstrating good temperature resistance. However, its pressure resistance is insufficient for pressure-driven process design.

[0013] Chinese patent application CN115960593A discloses a biodegradable temporary plugging agent. The agent is knot-shaped and composed of 72-80 parts biodegradable resin, 12-20 parts modified polyethylene glycol, 1-5 parts nanoparticle toughening agent, 1-5 parts salt toughening agent, and 1-3 parts water-blocking agent. While this temporary plugging agent improves plugging time to some extent, it is mainly suitable for low-temperature reservoirs at 20-60℃, and the knot's outer diameter is 13-18 mm. It is typically suitable for borehole plugging and has poor applicability for temporary plugging in pressure-driven fractures in high-temperature reservoirs.

[0014] Chinese patent application CN115820232A discloses a biodegradable temporary plugging agent, which uses complex raw materials, including polyethylene glycol (wt 60-80%), polyvinyl alcohol (wt 15-25%), zinc stearate (wt 0.5-2%), 2-acrylamido-2-methylpropanesulfonic acid (wt 0.5-2%), polybutylene succinate (wt 4-10%), triacetin (wt 0.1-0.5%), tributyl citrate (wt 0.1-0.5%), polyethylene wax (wt 0.3-0.7%), cationic starch (wt 0.1-0.5%), sepiolite fiber (wt 0.1-0.3%), calcium carbonate (wt 1.0-3.0%), hexamethylenetetramine (wt 0.5-1.0%), and trimethylallyl ammonium chloride (wt 0.5-1.0%). It is suitable for reservoirs with temperatures of 110–120°C and can withstand pressures of over 50 MPa. However, it has many components, is complex to prepare, and dissolves rapidly at high temperatures. The higher the temperature, the faster the dissolution. The dissolution time is 7 hours above 100°C. It has a short plugging time and cannot meet the design requirements of pressure-driven processes.

[0015] In summary, existing temporary plugging agents are mainly used in fracturing and acidizing operations, with fewer used as temporary plugging agents for hydraulic displacement. Hydraulic displacement differs significantly from fracturing and acidizing operations, involving not only higher injection pressures but also longer operation cycles. Therefore, temporary plugging agents used in hydraulic displacement require not only strong pressure resistance but also long sealing duration. Although there are many current temporary plugging agent systems, it remains difficult to simultaneously meet the requirements of high temperature resistance, high salt resistance, strong pressure resistance, and long sealing duration. Summary of the Invention

[0016] Purpose of the invention: To address the shortcomings of the prior art, this invention proposes a water suppression and anti-channeling temporary plugging system for pressure drive and its application, thereby improving the effectiveness of pressure drive water injection development in low-permeability reservoirs.

[0017] Technical solution: A water-suppressing and anti-channeling temporary plugging system for pressure-driven applications, comprising, by mass percentage, water-soluble fibers and soluble metal alloy particles, wherein:

[0018] The water-soluble fiber accounts for 5-15%;

[0019] The soluble metal alloy particles account for 85-95%.

[0020] Furthermore, the soluble metal alloy particles are magnesium alloy soluble metal particles, mainly composed of metallic magnesium, metallic aluminum, and metallic manganese, wherein:

[0021] The metal contains 5.0-10.0% aluminum, 0.1-0.5% manganese, ≤0.05% carbon, ≤0.01% nickel, ≤0.005% calcium, and the balance is magnesium.

[0022] Furthermore, the soluble metal alloy particles employ a combination of various particle sizes, wherein 20-40 mesh soluble metal alloy particles account for 30-40% of the mass, 40-70 mesh soluble metal alloy particles account for 40-50% of the mass, and the remainder is 70-100 mesh soluble metal alloy particles.

[0023] Furthermore, the apparent density of the soluble metal alloy particles is 0.15-0.40 g / cm³. 3 .

[0024] Furthermore, the water-soluble fiber is at least one of water-soluble polyvinyl alcohol fiber, seaweed fiber, carboxymethyl cellulose fiber, corn fiber, and polyglycolic acid fiber, preferably water-soluble polyvinyl alcohol fiber.

[0025] Furthermore, the length of the water-soluble fiber is 4-12 mm, and the content of insoluble matter in water is ≤0.5 wt%.

[0026] The application of any of the above-mentioned pressure drive water suppression and anti-channeling temporary plugging systems as pressure drive temporary plugging agents in low-permeability reservoirs.

[0027] Furthermore, the specific steps of the above application are as follows:

[0028] (1) Connecting the injection pipeline process, wherein: the injection pipeline process includes a liquid preparation tank equipped with stirring facilities and a high-pressure injection pump;

[0029] (2) Use a high-pressure injection pump to inject fluid through the injection well at a discharge rate greater than the formation’s absorption capacity. After the main fracture of the target formation is opened, add the above-mentioned pressure drive water suppression and anti-channeling temporary plugging system and an appropriate amount of fluid to the mixing tank and stir to form a pressure drive water suppression and anti-channeling temporary plugging system solution with a certain injection concentration.

[0030] (3) Using a high-pressure injection pump, inject the water-suppressing and anti-channeling temporary plugging system solution obtained in step (2) into the formation fracture through the injection well;

[0031] (4) When the injection pressure of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving reaches the difference between the maximum and minimum horizontal principal stresses of the target formation, the injection is stopped, and the injected fluid continues to replace the temporary plugging system material to the fracture end, and then normal pressure driving is switched.

[0032] Furthermore, when the width of the main fracture in the target formation is <1.0 cm, the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving is 0.8-1.5 wt%.

[0033] When the width of the main fracture in the target formation is ≥1.0cm, the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure drive is 1.0-2.0wt%.

[0034] Furthermore, in step (2), the water-soluble fiber and soluble metal alloy particles of the formula amount and an appropriate amount of fluid are added to the mixing tank and stirred and dispersed to obtain a pressure-driven water-suppressing and anti-channeling temporary blockage system solution of a certain injection concentration.

[0035] Furthermore, in step (3), the injection volume of the pressure-driven water-suppressing and anti-channeling temporary plugging system solution is greater than 1.5 times the column volume.

[0036] Furthermore, the fluid is one of water, an aqueous solution of a surfactant, or an aqueous solution of a polymer.

[0037] Furthermore, the mass concentration of the surfactant aqueous solution is 0.001%-5%, and the surfactant is one of fatty alcohol polyoxyethylene ether, alkanolamide, alkylphenol polyoxyethylene ether, petroleum sulfonate, and betaine-type surfactant.

[0038] Furthermore, the mass concentration of the polymer aqueous solution is 0.001%-2%, and the polymer is one of fructan, sodium alginate, polyacrylamide, and modified chitosan.

[0039] Furthermore, after the pressure drive in step (5) is completed, an acidic working fluid is injected into the target formation to unblock it, wherein:

[0040] The acid used in the acidic working solution is one of the following: hydrochloric acid, aminosulfonic acid, citric acid, acetic acid, formic acid, oxalic acid, phosphoric acid, and organic phosphoric acid;

[0041] The pH value of the acidic working solution is ≤6.

[0042] The water suppression and anti-channeling temporary clogging system for pressure drive disclosed in this invention has the following characteristics: good dynamic suspension, temperature resistance ≥130℃, and salt resistance ≥7×10⁻⁶. 4mg / L, pressure differential resistance ≥45MPa, plugging time ≥20d, plugging rate ≥95%, can be basically completely dissolved by using acidic degradation working solution, and the damage rate of the unblocking residue to the matrix is ​​<10%.

[0043] Beneficial effects: The beneficial effects of this invention are as follows:

[0044] (1) Compared with conventional temporary plugging agents, the present invention has higher pressure differential strength, stronger high-temperature resistance, stronger temperature and salt resistance, and longer effective plugging time, which can better meet the needs of long-term pressure drive operation.

[0045] (2) During the water injection pressure drive process, as the soluble metal alloy components gradually dissolve into smaller powder particles, the particles formed at the rear edge of the sealing section will continuously embed into the gaps of the temporary plugging material, and the powder particles formed at the front edge of the sealing section will enter deep small cracks or branch cracks, making the crack sealing more compact, the sealing rate higher, and the sealing stability stronger, further ensuring the sealing effect. Attached Figure Description

[0046] Figure 1 This is a graph showing the change in the plugging rate of the water suppression and anti-channeling temporary plugging system under different plugging times.

[0047] Figure 2 This is a graph showing the change in the plugging rate of the water-suppressing and anti-channeling temporary plugging system at different temperatures.

[0048] Figure 3 This is a curve showing the change in the plugging rate of the water suppression and anti-channeling temporary plugging system under different mineralization levels.

[0049] Figure 4 This is a graph showing the change in the dissolution and residual rate of the pressure-driven water suppression and anti-channeling temporary plugging system over time. Detailed Implementation

[0050] Unless otherwise specified, the experimental methods used in the following examples are standard methods. All reagents and materials used are commercially available unless otherwise specified.

[0051] Example 1

[0052] A pressure-driven water-suppressing and anti-channeling temporary plugging system, by mass percentage, is composed of water-soluble fibers and soluble metal alloy particles, wherein:

[0053] The water-soluble fiber accounts for 10%;

[0054] The soluble metal alloy particles account for 90%.

[0055] Furthermore, the soluble metal alloy particles are magnesium alloy soluble metal particles, mainly composed of metallic magnesium, metallic aluminum, and metallic manganese, wherein:

[0056] The metal contains 8.2% aluminum, 0.23% manganese, 0.03% carbon, 0.005% nickel, 0.003% calcium, and the balance is magnesium.

[0057] The soluble metal alloy particles can gradually dissolve in water into smaller powder particles. The particles formed at the rear edge of the sealing section will continuously embed into the gaps of the temporary plugging material, while the powder particles formed at the front edge of the sealing section will enter deep small cracks or branch cracks, thus enhancing the sealing effect.

[0058] Furthermore, the soluble metal alloy particles employ a combination of particle sizes, wherein 20-40 mesh soluble metal alloy particles account for 35% of the mass, 40-70 mesh soluble metal alloy particles account for 45% of the mass, and the remainder is 70-100 mesh soluble metal alloy particles.

[0059] Furthermore, the apparent density of the soluble metal alloy particles is 0.26 g / cm³. 3 .

[0060] Furthermore, the water-soluble fiber is a water-soluble polyvinyl alcohol fiber.

[0061] Furthermore, the water-soluble fiber has a length of 6 mm and a water-insoluble content of ≤0.5 wt%.

[0062] The above-mentioned water-suppressing and anti-channeling temporary plugging system for pressure drive is used as a temporary plugging agent for pressure drive in low-permeability reservoirs.

[0063] In a low-permeability reservoir of Shengli Oilfield, the injection pressure of water injection well A before temporary plugging was 35.3 MPa. The water suppression and anti-channeling temporary plugging system for pressure drive in Example 1 was used as the temporary plugging agent for pressure drive.

[0064] Furthermore, the specific steps of the above application are as follows:

[0065] (1) Connecting the injection pipeline process, wherein: the injection pipeline process includes a liquid preparation tank equipped with stirring facilities and a high-pressure injection pump;

[0066] (2) Use a high-pressure injection pump to inject fluid through the injection well at a discharge rate greater than the formation’s absorption capacity. After the main fracture of the target formation is opened, add the above-mentioned pressure drive water suppression and anti-channeling temporary plugging system and an appropriate amount of fluid to the mixing tank and stir to form a pressure drive water suppression and anti-channeling temporary plugging system solution with a certain injection concentration.

[0067] (3) Using a high-pressure injection pump, inject the water-suppressing and anti-channeling temporary plugging system solution obtained in step (2) into the formation fracture through the injection well;

[0068] (4) When the injection pressure of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving reaches the difference between the maximum and minimum horizontal principal stresses of the target formation, the injection is stopped, and the injected fluid continues to replace the temporary plugging system material to the fracture end, and then normal pressure driving is switched.

[0069] Furthermore, the width of the main fracture in the target formation is 0.8 cm, and the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving is 0.8 wt%.

[0070] Furthermore, in step (2), the water-soluble fiber and soluble metal alloy particles of the formula amount and an appropriate amount of fluid are added to the mixing tank and stirred and dispersed to obtain a pressure-driven water-suppressing and anti-channeling temporary blockage system solution of a certain injection concentration.

[0071] Furthermore, in step (3), the injection volume of the pressure-driven water-suppressing and anti-channeling temporary plugging system solution is greater than 1.5 times the column volume.

[0072] Furthermore, the fluid is water.

[0073] Furthermore, after the pressure drive in step (5) is completed, an acidic working fluid is injected into the target formation to unblock it, wherein:

[0074] The acid used in the acidic working solution is hydrochloric acid;

[0075] The pH value of the acidic working solution is ≤6.

[0076] After testing, the injection pressure of water injection well A in a low-permeability reservoir of Shengli Oilfield increased from 35.3 MPa to 36.9 MPa before and after temporary plugging, an increase of 1.6 MPa, indicating that effective plugging was formed in the fracture.

[0077] In Example 1, the pressure-driven water-suppressing and anti-channeling temporary plugging system was mixed uniformly with an appropriate amount of water to obtain a pressure-driven water-suppressing and anti-channeling temporary plugging system solution with an injection concentration of 0.8 wt%. Core displacement experiments were conducted to test the core fracture plugging rate of the above-mentioned pressure-driven water-suppressing and anti-channeling temporary plugging system solution at different plugging times. The results are as follows: Figure 1 As shown, its blocking rate is ≥98%.

[0078] Example 2

[0079] A pressure-driven water-suppressing and anti-channeling temporary plugging system, by mass percentage, is composed of water-soluble fibers and soluble metal alloy particles, wherein:

[0080] The water-soluble fiber accounts for 5%;

[0081] The soluble metal alloy particles account for 95%.

[0082] Furthermore, the soluble metal alloy particles are magnesium alloy soluble metal particles, mainly composed of metallic magnesium, metallic aluminum, and metallic manganese, wherein:

[0083] The metal contains 5.0% aluminum, 0.1% manganese, 0.01% carbon, 0.001% nickel, 0.001% calcium, and the balance is magnesium.

[0084] The soluble metal alloy particles can gradually dissolve in water into smaller powder particles. The particles formed at the rear edge of the sealing section will continuously embed into the gaps of the temporary plugging material, while the powder particles formed at the front edge of the sealing section will enter deep small cracks or branch cracks, thus enhancing the sealing effect.

[0085] Furthermore, the soluble metal alloy particles employ a combination of particle sizes, wherein 30% by mass are soluble metal alloy particles of 20-40 mesh, 40% by mass are soluble metal alloy particles of 40-70 mesh, and the remainder is soluble metal alloy particles of 70-100 mesh.

[0086] Furthermore, the apparent density of the soluble metal alloy particles is 0.15 g / cm³. 3 .

[0087] Furthermore, the water-soluble fiber is seaweed fiber.

[0088] Furthermore, the water-soluble fiber has a length of 4 mm and a water-insoluble content of ≤0.5 wt%.

[0089] The aforementioned water-suppressing and anti-channeling temporary plugging system for pressure drive is used as a temporary plugging agent in low-permeability reservoirs.

[0090] In a low-permeability reservoir of Shengli Oilfield, the injection pressure of water injection well B before temporary plugging was 40.2 MPa. The water-suppressing and anti-channeling temporary plugging system for pressure drive in Example 2 was used as the temporary plugging agent for pressure drive.

[0091] Furthermore, the specific steps of the above application are as follows:

[0092] (1) Connecting the injection pipeline process, wherein: the injection pipeline process includes a liquid preparation tank equipped with stirring facilities and a high-pressure injection pump;

[0093] (2) Use a high-pressure injection pump to inject fluid through the injection well at a discharge rate greater than the formation’s absorption capacity. After the main fracture of the target formation is opened, add the above-mentioned pressure drive water suppression and anti-channeling temporary plugging system and an appropriate amount of fluid to the mixing tank and stir to form a pressure drive water suppression and anti-channeling temporary plugging system solution with a certain injection concentration.

[0094] (3) Using a high-pressure injection pump, inject the water-suppressing and anti-channeling temporary plugging system solution obtained in step (2) into the formation fracture through the injection well;

[0095] (4) When the injection pressure of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving reaches the difference between the maximum and minimum horizontal principal stresses of the target formation, the injection is stopped, and the injected fluid continues to replace the temporary plugging system material to the fracture end, and then normal pressure driving is switched.

[0096] Furthermore, the width of the main fracture in the target formation is 0.89 cm, and the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving is 1.5 wt%.

[0097] Furthermore, in step (2), the water-soluble fiber and soluble metal alloy particles of the formula amount and an appropriate amount of fluid are added to the mixing tank and stirred and dispersed to obtain a pressure-driven water-suppressing and anti-channeling temporary blockage system solution of a certain injection concentration.

[0098] Furthermore, in step (3), the injection volume of the pressure-driven water-suppressing and anti-channeling temporary plugging system solution is greater than 1.5 times the column volume.

[0099] Furthermore, the fluid is an aqueous solution of a surfactant.

[0100] Furthermore, the surfactant aqueous solution has a mass concentration of 3% and is a fatty alcohol polyoxyethylene ether aqueous solution. In another embodiment, the surfactant aqueous solution has a mass concentration of 0.001% and the surfactant is an alkanolamide. In another embodiment, the surfactant aqueous solution has a mass concentration of 5% and the surfactant is an alkylphenol polyoxyethylene ether. In another embodiment, the surfactant aqueous solution has a mass concentration of 1% and the surfactant is a petroleum sulfonate. In another embodiment, the surfactant aqueous solution has a mass concentration of 4% and the surfactant is a betaine-type surfactant.

[0101] Furthermore, after the pressure drive in step (5) is completed, an acidic working fluid is injected into the target formation to unblock it, wherein:

[0102] The acid used in the acidic working solution is aminosulfonic acid;

[0103] The pH value of the acidic working solution is ≤6.

[0104] After testing, the injection pressure of water injection well B in a low-permeability reservoir of Shengli Oilfield increased from 40.2 MPa to 42.0 MPa before and after temporary plugging, an increase of 1.8 MPa, and the surface formed an effective seal in the fracture.

[0105] The pressure-driven water-suppressing and anti-channeling temporary plugging system of Example 2 was mixed evenly with an appropriate amount of 3% (w / w) fatty alcohol polyoxyethylene ether aqueous solution to obtain a 1.5 wt% pressure-driven water-suppressing and anti-channeling temporary plugging system solution. Core displacement experiments were conducted to test the core fracture sealing rate of the above-mentioned pressure-driven water-suppressing and anti-channeling temporary plugging system solution under different temperature conditions (room temperature - 130℃). The results are as follows: Figure 2 As shown, its blocking rate is ≥96%.

[0106] Example 3

[0107] A pressure-driven water-suppressing and anti-channeling temporary plugging system, by mass percentage, is composed of water-soluble fibers and soluble metal alloy particles, wherein:

[0108] The water-soluble fiber accounts for 15%;

[0109] The soluble metal alloy particles account for 85%.

[0110] Furthermore, the soluble metal alloy particles are magnesium alloy soluble metal particles, mainly composed of metallic magnesium, metallic aluminum, and metallic manganese, wherein:

[0111] The metal contains 10.0% aluminum, 0.5% manganese, 0.045% carbon, 0.01% nickel, 0.005% calcium, and the balance is magnesium.

[0112] The soluble metal alloy particles can gradually dissolve in water into smaller powder particles. The particles formed at the rear edge of the sealing section will continuously embed into the gaps of the temporary plugging material, while the powder particles formed at the front edge of the sealing section will enter deep small cracks or branch cracks, thus enhancing the sealing effect.

[0113] Furthermore, the soluble metal alloy particles employ a combination of particle sizes, wherein 40% by mass are soluble metal alloy particles of 20-40 mesh, 50% by mass are soluble metal alloy particles of 40-70 mesh, and the remainder is soluble metal alloy particles of 70-100 mesh.

[0114] Furthermore, the apparent density of the soluble metal alloy particles is 0.40 g / cm³. 3 .

[0115] Furthermore, the water-soluble fiber is carboxymethyl cellulose fiber.

[0116] Furthermore, the water-soluble fiber has a length of 12 mm and a water-insoluble content of ≤0.5 wt%.

[0117] The aforementioned water-suppressing and anti-channeling temporary plugging system for pressure drive is used as a temporary plugging agent in low-permeability reservoirs.

[0118] In a low-permeability reservoir of Shengli Oilfield, the injection pressure of water injection well C before temporary plugging was 38.2 MPa. The water suppression and anti-channeling temporary plugging system for pressure drive described in Example 3 was used as the temporary plugging agent for pressure drive.

[0119] Furthermore, the specific steps of the above application are as follows:

[0120] (1) Connecting the injection pipeline process, wherein: the injection pipeline process includes a liquid preparation tank equipped with stirring facilities and a high-pressure injection pump;

[0121] (2) Use a high-pressure injection pump to inject fluid through the injection well at a discharge rate greater than the formation’s absorption capacity. After the main fracture of the target formation is opened, add the above-mentioned pressure drive water suppression and anti-channeling temporary plugging system and an appropriate amount of fluid to the mixing tank and stir to form a pressure drive water suppression and anti-channeling temporary plugging system solution with a certain injection concentration.

[0122] (3) Using a high-pressure injection pump, inject the water-suppressing and anti-channeling temporary plugging system solution obtained in step (2) into the formation fracture through the injection well;

[0123] (4) When the injection pressure of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving reaches the difference between the maximum and minimum horizontal principal stresses of the target formation, the injection is stopped, and the injected fluid continues to replace the temporary plugging system material to the fracture end, and then normal pressure driving is switched.

[0124] Furthermore, the width of the main fracture in the target formation is 1.2 cm, and the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving is 1.0 wt%.

[0125] Furthermore, in step (2), the water-soluble fiber and soluble metal alloy particles of the formula amount and an appropriate amount of fluid are added to the mixing tank and stirred and dispersed to obtain a pressure-driven water-suppressing and anti-channeling temporary blockage system solution of a certain injection concentration.

[0126] Furthermore, in step (3), the injection volume of the pressure-driven water-suppressing and anti-channeling temporary plugging system solution is greater than 1.5 times the column volume.

[0127] Furthermore, the fluid is an aqueous polymer solution.

[0128] Furthermore, the polymer aqueous solution has a mass concentration of 1%, and the polymer is fructan. In another embodiment, the polymer aqueous solution has a mass concentration of 0.001%, and the polymer is sodium alginate. In another embodiment, the polymer aqueous solution has a mass concentration of 2%, and the polymer is polyacrylamide. In yet another embodiment, the polymer aqueous solution has a mass concentration of 0.5%, and the polymer is modified chitosan.

[0129] Furthermore, after the pressure drive in step (5) is completed, an acidic working fluid is injected into the target formation to unblock it, wherein:

[0130] The acid used in the acidic working solution is citric acid;

[0131] The pH value of the acidic working solution is ≤6.

[0132] After testing, the injection pressure of water injection well C in a low-permeability reservoir of Shengli Oilfield increased from 38.2 MPa to 40.1 MPa before and after temporary plugging, an increase of 1.9 MPa, and the surface formed an effective seal in the fracture.

[0133] The pressure-driven water-suppressing and anti-channeling temporary plugging system of Example 3 was mixed evenly with a 1% fructan aqueous solution to prepare a 1.0 wt% pressure-driven water-suppressing and anti-channeling temporary plugging system solution. The core displacement experiment was used to test the core fracture sealing rate of the pressure-driven water-suppressing and anti-channeling temporary plugging system solution under different salinity conditions. The results are as follows: Figure 3 As shown, its blocking rate is ≥98%.

[0134] Example 4

[0135] A pressure-driven water-suppressing and anti-channeling temporary plugging system, by mass percentage, is composed of water-soluble fibers and soluble metal alloy particles, wherein:

[0136] The water-soluble fiber accounts for 8%;

[0137] The soluble metal alloy particles account for 92%.

[0138] Furthermore, the soluble metal alloy particles are magnesium alloy soluble metal particles, mainly composed of metallic magnesium, metallic aluminum, and metallic manganese, wherein:

[0139] The metal contains 6% aluminum, 0.3% manganese, 0.03% carbon, 0.01% nickel, 0.005% calcium, and the balance is magnesium.

[0140] The soluble metal alloy particles can gradually dissolve in water into smaller powder particles. The particles formed at the rear edge of the sealing section will continuously embed into the gaps of the temporary plugging material, while the powder particles formed at the front edge of the sealing section will enter deep small cracks or branch cracks, thus enhancing the sealing effect.

[0141] Furthermore, the soluble metal alloy particles employ a combination of various particle sizes, wherein 20-40 mesh soluble metal alloy particles account for 32% of the mass, 40-70 mesh soluble metal alloy particles account for 42% of the mass, and the remainder is 70-100 mesh soluble metal alloy particles.

[0142] Furthermore, the apparent density of the soluble metal alloy particles is 0.34 g / cm³. 3 .

[0143] Further, the water-soluble fiber is corn fiber. In another embodiment, the water-soluble fiber is polyglycolic acid fiber. In yet another embodiment, the water-soluble fiber is a mixture of water-soluble polyvinyl alcohol fiber, seaweed fiber, carboxymethyl cellulose fiber, corn fiber, and polyglycolic acid fiber in equal mass ratios.

[0144] Furthermore, the water-soluble fiber has a length of 6 mm and a water-insoluble content of ≤0.5 wt%.

[0145] The aforementioned water-suppressing and anti-channeling temporary plugging system for pressure drive is used as a temporary plugging agent in low-permeability reservoirs.

[0146] In a low-permeability reservoir of Shengli Oilfield, the injection pressure of injection well D before temporary plugging was 41.3 MPa. The water-suppressing and anti-channeling temporary plugging system for pressure drive in Example 4 was used as the temporary plugging agent for pressure drive.

[0147] Furthermore, the specific steps of the above application are as follows:

[0148] (1) Connecting the injection pipeline process, wherein: the injection pipeline process includes a liquid preparation tank equipped with stirring facilities and a high-pressure injection pump;

[0149] (2) Use a high-pressure injection pump to inject fluid through the injection well at a discharge rate greater than the formation’s absorption capacity. After the main fracture of the target formation is opened, add the above-mentioned pressure drive water suppression and anti-channeling temporary plugging system and an appropriate amount of fluid to the mixing tank and stir to form a pressure drive water suppression and anti-channeling temporary plugging system solution with a certain injection concentration.

[0150] (3) Using a high-pressure injection pump, inject the water-suppressing and anti-channeling temporary plugging system solution obtained in step (2) into the formation fracture through the injection well;

[0151] (4) When the injection pressure of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving reaches the difference between the maximum and minimum horizontal principal stresses of the target formation, the injection is stopped, and the injected fluid continues to replace the temporary plugging system material to the fracture end, and then normal pressure driving is switched.

[0152] Furthermore, the width of the main fracture in the target formation is 2.0 cm, and the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving is 2.0 wt%.

[0153] Furthermore, in step (2), the water-soluble fiber and soluble metal alloy particles of the formula amount and an appropriate amount of fluid are added to the mixing tank and stirred and dispersed to obtain a pressure-driven water-suppressing and anti-channeling temporary blockage system solution of a certain injection concentration.

[0154] Furthermore, in step (3), the injection volume of the pressure-driven water-suppressing and anti-channeling temporary plugging system solution is greater than 1.5 times the column volume.

[0155] Furthermore, the fluid is water.

[0156] Furthermore, after the pressure drive in step (5) is completed, an acidic working fluid is injected into the target formation to unblock it, wherein:

[0157] The acid used in the acidic working solution is acetic acid; the pH value of the acidic working solution is ≤6. In another embodiment, the acid used in the acidic working solution is formic acid. In another embodiment, the acid used in the acidic working solution is oxalic acid. In another embodiment, the acid used in the acidic working solution is phosphoric acid. In another embodiment, the acid used in the acidic working solution is organic phosphoric acid.

[0158] After testing, the injection pressure of water injection well D in a low-permeability reservoir of Shengli Oilfield increased from 41.3MPa to 43.5MPa before and after temporary plugging, an increase of 2.2MPa, and the surface formed an effective seal in the fracture.

[0159] A certain amount of the water-suppressing and anti-channeling temporary plugging system of Example 4 was placed in water with a pH of 3 at an environment of 110-130℃ for a residue rate test. After 5 hours, the material of the temporary plugging system was basically completely dissolved. The results are as follows: Figure 4 As shown, the solubility is >99%.

[0160] Performance standards:

[0161] Test Example 1

[0162] The pressure-driven water-suppressing and anti-channeling temporary plugging system from Example 4 was mixed with water to prepare a 1% (w / w) aqueous solution. Core permeability damage was assessed using a core displacement device, and the results showed an average damage rate of 8.12%. Compared with the damage assessment results for cores treated with clear water, the liquid from the dissolved pressure-driven water-suppressing and anti-channeling temporary plugging system increased the core permeability damage rate by approximately 2.73%.

[0163] Table 1. Damage assessment results of Qingshui rock cores

[0164]

[0165] Table 2. Evaluation results of liquid core damage after dissolution of the pressure-driven water suppression and anti-channeling temporary plugging system.

[0166]

[0167] Test Example 2

[0168] It is equipped with commonly used gel-type temporary plugging agents and oilfield-grade fiber-based temporary plugging agents (PVA).

[0169] High-temperature and high-salinity core displacement test: For Examples 1, 2, and 3, the commonly used gel-type temporary plugging agent and the fiber-type temporary plugging agent (PVA) used in oilfields will be displacementd for 3 days under conditions of 80℃ and constant pressure difference of 20MPa, and the fracture sealing rate will be compared.

[0170] Table 3. Blocking Rate Test Results

[0171]

[0172]

[0173] According to the core displacement effect test results, after displacement for 3 days at 80℃ and constant pressure of 20MPa, the fracture sealing rate of the water suppression and anti-channeling temporary plugging system of the present invention, which is suitable for pressure drive in low-permeability reservoirs, is significantly higher than that of commonly used gel-type temporary plugging agents and fiber-type temporary plugging agents (PVA) used in oil fields.

[0174] Test Example 3

[0175] High-temperature and high-salinity core displacement test: For Examples 1, 2, and 3, commonly used oilfield gel-type temporary plugging agent and oilfield fiber-type temporary plugging agent (PVA) were tested in an 80℃ environment, with the injection pressure gradually increased from 5MPa to 45MPa. The test observed whether the temporary plugging section in the fracture was broken down and tested its pressure difference resistance performance.

[0176] Table 4. Results of Compressive Strength Test

[0177]

[0178] According to the core displacement effect test results, the pressure-bearing capacity of the water-suppressing and anti-channeling temporary plugging system of the present invention, which is suitable for pressure drive in low-permeability reservoirs, is significantly higher than that of commonly used gel-type temporary plugging agents and fiber-type temporary plugging agents (PVA) used in oil fields.

[0179] In summary, the pressure-driven water suppression and anti-channeling temporary clogging system disclosed in this invention exhibits good dynamic suspension properties and a temperature resistance of ≥130℃ (see...). Figure 2 Salt tolerance ≥7×10 4 mg / L (see Figure 3 ), sealing time ≥ 20 days (see Figure 1 Using an acidic degradation working solution, it can be basically completely dissolved, and the damage rate of the unblocking residue to the matrix is ​​less than 10%.

[0180] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A pressure-driven water suppression and anti-channeling temporary plugging system, characterized in that, It is composed of water-soluble fibers and soluble metal alloy particles by mass percentage, wherein: The water-soluble fiber accounts for 5-15%; The soluble metal alloy particles account for 85-95%; The soluble metal alloy particles are magnesium alloy soluble metal particles, mainly composed of metallic magnesium, metallic aluminum and metallic manganese; The soluble metal alloy particles are composed of a variety of particle size combinations, wherein the mass proportion of soluble metal alloy particles of 20-40 mesh is 30-40%, the mass proportion of soluble metal alloy particles of 40-70 mesh is 40-50%, and the remainder is soluble metal alloy particles of 70-100 mesh. The apparent density of the soluble metal alloy particles is 0.15-0.40 g / cm³. 3 ; The water-soluble fiber is at least one of water-soluble polyvinyl alcohol fiber, seaweed fiber, carboxymethyl cellulose fiber, corn fiber, and polyglycolic acid fiber.

2. The pressure-driven water suppression and anti-channeling temporary plugging system as described in claim 1, characterized in that, The composition of the soluble metal alloy particles is as follows: The metal contains 5.0-10.0% aluminum, 0.1-0.5% manganese, ≤0.05% carbon, ≤0.01% nickel, ≤0.005% calcium, and the balance is magnesium.

3. The pressure-driven water suppression and anti-channeling temporary plugging system as described in claim 1, characterized in that, The water-soluble fiber is water-soluble polyvinyl alcohol fiber.

4. The pressure-driven water suppression and anti-channeling temporary plugging system as described in claim 1, characterized in that, The water-soluble fiber has a length of 4-12 mm and a water-insoluble content of ≤0.5 wt%.

5. The application of the pressure-driven water-suppressing and anti-channeling temporary plugging system according to any one of claims 1-4 as a temporary plugging agent for pressure driving in low-permeability reservoirs.

6. The application as described in claim 5, characterized in that, The specific steps for the above application are as follows: (1) Connecting the injection pipeline process, wherein: the injection pipeline process includes a liquid preparation tank equipped with stirring facilities and a high-pressure injection pump; (2) Use a high-pressure injection pump to inject fluid through the injection well at a discharge rate greater than the formation’s absorption capacity. After the main fracture of the target formation is opened, add the above-mentioned pressure drive water suppression and anti-channeling temporary plugging system and an appropriate amount of fluid to the mixing tank and stir to form a pressure drive water suppression and anti-channeling temporary plugging system solution with a certain injection concentration. (3) Using a high-pressure injection pump, inject the water-suppressing and anti-channeling temporary plugging system solution obtained in step (2) into the formation fracture through the injection well; (4) When the injection pressure of the water-suppressing and anti-channeling temporary plugging system solution for pressure driving reaches the difference between the maximum and minimum horizontal principal stresses of the target formation, the injection is stopped, and the injected fluid continues to replace the temporary plugging system material to the fracture end, and then normal pressure driving is switched.

7. The application as described in claim 6, characterized in that, When the width of the main fracture in the target formation is <1.0 cm, the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure drive is 0.8-1.5 wt%. When the width of the main fracture in the target formation is ≥1.0cm, the injection concentration of the water-suppressing and anti-channeling temporary plugging system solution for pressure drive is 1.0-2.0wt%.

8. The application as described in claim 6, characterized in that, In step (2), the water-soluble fiber and soluble metal alloy particles of the formula amount and an appropriate amount of fluid are added to the mixing tank and stirred and dispersed to obtain a pressure drive water suppression and anti-channeling temporary blockage system solution with a certain injection concentration.

9. The application as described in claim 6, characterized in that, In step (3), the injection volume of the water-suppressing and anti-channeling temporary plugging system solution for pressure drive is greater than 1.5 times the column volume.

10. The application as described in claim 6, characterized in that, The fluid is one of water, an aqueous solution of a surfactant, or an aqueous solution of a polymer.

11. The application as described in claim 10, characterized in that, The mass concentration of the surfactant aqueous solution is 0.001%-5%, and the surfactant is one of fatty alcohol polyoxyethylene ether, alkanolamide, alkylphenol polyoxyethylene ether, petroleum sulfonate, and betaine-type surfactant.

12. The application as described in claim 10, characterized in that, The polymer aqueous solution has a mass concentration of 0.001%-2%, and the polymer is one of fructan, sodium alginate, polyacrylamide, and modified chitosan.

13. The application as described in claim 6, characterized in that, This also includes step (5), after the pressure drive is completed, injecting acidic working fluid into the target formation to unblock it, wherein: The acid used in the acidic working solution is one of the following: hydrochloric acid, aminosulfonic acid, citric acid, acetic acid, formic acid, oxalic acid, phosphoric acid, and organic phosphoric acid; The pH value of the acidic working solution is ≤6.

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