Novel oil-permeable water-blocking membrane preflush, preparation method thereof and fracturing fluid

Abstract

The application discloses a novel oil-permeable water-blocking film preflush, a preparation method thereof and a fracturing fluid. The novel oil-permeable water-blocking film preflush comprises a solvent, a film body, a pore-forming agent and a hydrophobic agent. The pore-forming agent is used for forming pores in the film body, and the hydrophobic agent is used for making the film body hydrophobic. The preparation method of the novel oil-permeable water-blocking film preflush comprises the following steps: firstly, the solvent, the film body and the pore-forming agent are uniformly mixed at 40-120 DEG C to obtain a mixed solution one; after the mixed solution one is cooled to room temperature, the hydrophobic agent is added, and then the mixed solution one is uniformly mixed at 30-60 DEG C to obtain a mixed solution two; the mixed solution two is kept at a constant temperature of 40-60 DEG C for 24-36 hours to obtain the novel oil-permeable water-blocking film preflush. The novel oil-permeable water-blocking film preflush can form an oil-permeable water-blocking film with pores in fractured rocks, so that water control from the formation is realized, the water control effect is improved, and the oil and gas production is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas production enhancement and modification, and in particular to a novel oil-permeable and water-blocking film pre-fluid, a preparation method thereof, and a fracturing fluid. Background Art

[0002] Unconventional oil and gas reservoirs struggle to generate commercial gas flows without hydraulic fracturing and other stimulation techniques. Hydraulic fracturing involves injecting a pre-fluid into the target reservoir at a pressure exceeding the formation's fracture pressure, creating extended fractures. A sand-carrying fluid mixed with proppant is then injected into the fractures. Finally, the injected fracturing fluid is returned to the surface, leaving a propped, highly conductive fracture and increasing the reservoir's permeability. However, the artificial fractures created by hydraulic fracturing can lead to rapid increases in the water content of oil and gas wells. Therefore, addressing both the rapid increase in water content and the need to increase production after fracturing has become a key research priority for scholars both domestically and internationally.

[0003] Currently, the commonly used method is to control water flow by inserting an inflow controller. This method separates water within the wellbore to achieve water control, but cannot control water from the fractures. Therefore, the development of a fracturing fluid with oil-permeability and water-blocking properties can not only increase oil and gas well production, but also prevent the damage caused by excessive water release from the formation after fracturing. Summary of the Invention

[0004] In response to the above problems, the present invention aims to provide a new type of oil-permeable and water-blocking film pre-fluid, its preparation method and fracturing fluid, which forms a solid oil-permeable and water-blocking film with pores in the formation cracks and uses the film to achieve oil-permeability and water-blocking.

[0005] The technical solutions of the present invention are as follows:

[0006] On the one hand, a novel oil-permeable and water-blocking film pre-fluid is provided, comprising a solvent, a membrane body, a porogen and a hydrophobic agent, wherein the porogen is used to make the membrane body porous, and the hydrophobic agent is used to make the membrane body hydrophobic.

[0007] Preferably, the membrane body is one or more of polyvinylidene fluoride, polyethersulfone, polysulfone, ethylene-vinyl alcohol copolymer, polyimide, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polyetherimide, polyetheretherketone, polycarbonate, and polyacrylamide.

[0008] Preferably, the solvent is any one of N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, triethyl phosphate, dimethylaminoethanol, dichloroethane, and acetone.

[0009] Preferably, the porogen is any one or more of ethylene glycol, polyvinyl pyrrolidone, glycerol, polyethylene glycol, ethylene glycol, ethanol, propanol, butanol, and water.

[0010] Preferably, the hydrophobic agent is any one or more of a fatty alcohol polyoxyethylene ether modified silicone surfactant, sodium methyl silicate, and a silicone quaternary ammonium salt.

[0011] Preferably, the weight proportions of the components are as follows: 50-95 parts of solvent, 5-35 parts of membrane body, 1-2 parts of porogen and 2-6 parts of hydrophobic agent.

[0012] On the other hand, a method for preparing the novel oil-permeable and water-blocking film pre-fluid as described in any one of the above is also provided, comprising the following steps:

[0013] First, the solvent, the membrane body and the porogen are uniformly mixed at 40-120° C. to obtain a mixed solution 1;

[0014] After the mixed solution 1 is cooled to room temperature, the hydrophobic agent is added, and then mixed uniformly at 30-60° C. to obtain a mixed solution 2;

[0015] The mixed solution 2 is kept at a constant temperature of 40-60° C. for 24-36 hours to obtain the novel oil-permeable and water-blocking film pre-fluid.

[0016] On the other hand, a new oil-permeable and water-blocking film fracturing fluid is provided, comprising 1%-20% of a pre-fluid and 80%-99% of a sand-carrying fluid, wherein the pre-fluid is any of the above-mentioned new oil-permeable and water-blocking film pre-fluids.

[0017] Preferably, the sand-carrying fluid comprises 980-999 parts of a water-based fracturing fluid and 1-20 parts of an inorganic salt.

[0018] Preferably, the conventional fracturing fluid is slick water fracturing fluid or guar gum fracturing fluid; and the inorganic salt is one or more of sodium chloride, lithium chloride, phosphoric acid, ammonium chloride, calcium chloride, sodium nitrate, sodium sulfate, sodium bisulfite, and calcium sulfate.

[0019] The beneficial effects of the present invention are:

[0020] The prefluid of the present invention can form a porous, oil-permeable, and water-controlling film in fractured rock, thereby controlling water from the formation, improving water control effectiveness, and increasing oil and gas production. The fracturing fluid of the present invention can reduce filtration of fracturing fluid into the formation during construction, thereby reducing formation damage and improving fracturing effectiveness. It also eliminates the risk of blocking the formation and does not affect the original outflow of oil and gas. It adheres tightly to the formation, enabling long-term, effective water control. It is also low-cost, and the oil-permeable, water-controlling concept is clear and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of the formation and oil-permeable and water-blocking mechanism of the novel oil-permeable and water-blocking film of the present invention;

[0023] Figure 2 This is a schematic diagram of the construction process of the novel oil-permeable and water-blocking film fracturing of the present invention;

[0024] Figure 3 This is a schematic diagram of the results of a novel oil-permeable and water-blocking film according to a specific embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the results of a measuring cylinder water blocking test on a novel oil-permeable and water-blocking film according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described below with reference to the accompanying drawings and examples. It should be noted that, in the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other. It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those commonly understood by those of ordinary skill in the art to which this application belongs. The use of similar words such as "include" or "comprising" in the present invention means that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0027] On the one hand, the present invention provides a novel oil-permeable and water-blocking film pre-fluid, which comprises the following components by weight: 50-95 parts of solvent, 5-35 parts of membrane body, 1-2 parts of porogen and 2-6 parts of hydrophobic agent, wherein the porogen is used to make the membrane body porous, and the hydrophobic agent is used to make the membrane body hydrophobic.

[0028] In a specific embodiment, the membrane body is one or more of polyvinylidene fluoride, polyethersulfone, polysulfone, ethylene-vinyl alcohol copolymer, polyimide, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polyetherimide, polyetheretherketone, polycarbonate, and polyacrylamide; the solvent is any one of N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, triethyl phosphate, dimethylaminoethanol, dichloroethane, and acetone; the porogen is any one of ethylene glycol, polyvinyl pyrrolidone, glycerol, polyethylene glycol, ethylene glycol, ethanol, propanol, butanol, and water; the hydrophobic agent is any one or more of fatty alcohol polyoxyethylene ether-modified silicone surfactant, sodium methyl silicate, and silicone quaternary ammonium salt.

[0029] It should be noted that the solvent described in the present invention is to dissolve the membrane body, porogen and hydrophobic agent. In addition to the solvent used in the above embodiment, other solvents in the prior art can also be applied to the present invention; the porogen described in the present invention is to make the membrane body porous. Those skilled in the art can select other porogens that can make the membrane body porous according to the selected membrane body; the hydrophobic agent described in the present invention is to make the membrane body hydrophobic, thereby achieving the purpose of water control. In addition to the hydrophobic agent used in the above embodiment, those skilled in the art can select other hydrophobic agents that can make the membrane body hydrophobic according to the selected membrane body.

[0030] In a specific embodiment, the novel oil-permeable and water-blocking film pre-fluid is prepared by the following steps: first, the solvent is mixed evenly with the membrane body and the porogen at 40-120°C to obtain a mixed solution one; after the mixed solution one is cooled to room temperature, the hydrophobic agent is added, and then the mixed solution is mixed evenly at 30-60°C to obtain a mixed solution two; the mixed solution two is kept at a constant temperature of 40-60°C for 24-36 hours to obtain the novel oil-permeable and water-blocking film pre-fluid.

[0031] In the above embodiment, the viscosity and uniformity of the cooled mixed solution 1 facilitate the addition of the hydrophobic agent, while reheating facilitates more uniform incorporation of the hydrophobic agent. Optionally, cooling can be performed at room temperature or using a water bath or other cooling methods. Furthermore, allowing the mixed solution 2 to stand at a constant temperature can remove bubbles from the mixed solution, thereby improving the film-forming effect of the novel oil-permeable and water-blocking film pre-pad solution.

[0032] On the other hand, the present invention also provides a novel oil-permeable and water-blocking film fracturing fluid, comprising 1%-20% of a pre-fluid and 80%-99% of a sand-carrying fluid, wherein the pre-fluid is any of the novel oil-permeable and water-blocking film pre-fluids described above.

[0033] In a specific embodiment, the sand-carrying fluid comprises 980-999 parts of a water-based fracturing fluid and 1-20 parts of an inorganic salt; the conventional fracturing fluid is a slick water fracturing fluid or a guar gum fracturing fluid; and the inorganic salt is one or more of sodium chloride, lithium chloride, phosphoric acid, ammonium chloride, calcium chloride, sodium nitrate, sodium sulfate, sodium bisulfite, and calcium sulfate.

[0034] When the novel oil-permeable and water-blocking film fracturing fluid of the present invention is used for fracturing transformation, the construction process is as follows:

[0035] (1) The novel oil-permeable and water-blocking film pre-fluid of the present invention is pumped into the formation at a high pressure higher than the formation fracture pressure to form a fracture.

[0036] (2) Pumping in a sand-carrying fluid according to construction requirements, wherein the ratio of the sand-carrying fluid to the pre-fluid in step (1) is 80-95:5-20. The proppant concentration, proppant particle size and type of the sand-carrying fluid are determined according to the specific fracturing fluid construction requirements.

[0037] (3) Injecting displacement fluid, which is commonly used displacement fluid in oil fields and has no special requirements.

[0038] (4) Drain the liquid in accordance with the principles of control, continuity and stability.

[0039] like Figure 1-2 As shown, the novel oil-permeable and water-blocking film pre-fluid of the present invention forms a solid film with certain strength and porosity and oil-permeable and hydrophobic effect after meeting the water-based sand-carrying fluid, and water control in the formation is achieved through the solid film.

[0040] Example 1

[0041] A novel oil-permeable and water-blocking film fracturing fluid is prepared by the following steps:

[0042] (1) Weigh 75 parts of ethylene dichloride, 20 parts of polysulfone, and 2 parts of polyethylene glycol, mix them uniformly at 80°C, then keep them at 80°C and then cool them at room temperature to obtain a mixed solution A, which is kept at room temperature for later use.

[0043] (2) Weigh 3 parts of sodium methyl silicate and 1 part of fatty alcohol polyoxyethylene ether modified silicone surfactant, add them to mixed solution A, mix them evenly at 40°C, and place them in a 40°C oven for 24 hours to obtain mixed solution B.

[0044] (3) Weigh 1000 parts of water, 10 parts of drag reducer, 10 parts of drainage aid, 20 parts of clay stabilizer and 15 parts of sodium chloride and mix them evenly at room temperature to obtain a mixed solution C.

[0045] (4) Weigh 5 parts of mixed solution B and 450 parts of mixed solution C, place mixed solution B in mixed solution C, and obtain an oil-permeable and water-blocking film. The results are as follows: Figure 3 shown.

[0046] Example 2

[0047] Different from Example 1, the membrane body used in this embodiment is polyvinylidene fluoride, the solvent is acetone, the porogen is polyvinyl pyrrolidone, the hydrophobic agent is a silicone surfactant modified with fatty alcohol polyoxyethylene ether, the temperature of step (1) is 60°C, and the time of step (2) is 30°C.

[0048] Example 3

[0049] Different from Example 1, the hydrophobic agent added in step (2) in this embodiment is 6 parts of sodium methyl silicate, and the amount of drag reducer added in step (3) is 1 part of drag reducer, 1 part of drainage aid, 1 part of clay stabilizer, and 5 parts of calcium chloride.

[0050] Example 4

[0051] Different from Example 2, this example uses 6 parts of fatty alcohol polyoxyethylene ether modified silicone surfactant as a hydrophobic agent, and the silicone surfactant is placed in an oven and allowed to stand for 30 hours.

[0052] The contact angle tests were performed on the oil-permeable and water-blocking films prepared in Examples 1-4. The contact angles of the oil-permeable and water-blocking films of each example with water were measured using a contact angle device, as shown in Table 1.

[0053] Table 1 Contact angle test results of oil-permeable and water-blocking films and water

[0054] Example Example 1 Example 2 Example 3 Example 4 contact angle 137.2° 122.9° 143.7° 136.4°

[0055] It can be seen from Table 1 that the film formed by the novel oil-permeable and water-blocking film fracturing fluid of the present invention has good hydrophobic properties.

[0056] In addition, a water blocking test was conducted on the film prepared in Example 1 by filling a sand-filled measuring cylinder to test the barrier properties of the oil-permeable and water-blocking film of the present invention. The steps for this test are as follows:

[0057] 1. Add 30 ml of 70 / 140 mesh proppant into a measuring cylinder and add 2 g of mixed solution B in Example 1 onto the surface of the proppant;

[0058] 2. The mixed solution C in Example 1 was continuously added to the film to observe the wettability of the proppant by water and the time it took to reach the bottom.

[0059] The experimental results are as follows Figure 4 As shown, from Figure 4It can be seen that the mixed liquid B can effectively form a thin film and prevent the fracturing fluid from penetrating into the interior of the proppant.

[0060] In summary, the present invention can form a porous oil-permeable and water-controlling film in fractured rocks, thereby controlling water from the formation, improving the water control effect, and increasing oil and gas production. Compared with the existing technology, it has significant progress.

[0061] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An oil-permeable and water-blocking film pre-pad, characterized in that: In parts by weight, it comprises 50-95 parts of solvent, 5-35 parts of membrane body, 1-2 parts of porogen and 2-6 parts of hydrophobic agent, wherein the porogen is used to make the membrane body porous, and the hydrophobic agent is used to make the membrane body hydrophobic; The membrane body is one or more of polyvinylidene fluoride, polysulfone, and polyvinylidene fluoride; The hydrophobic agent is any one or more of a fatty alcohol polyoxyethylene ether modified silicone surfactant, sodium methyl silicate, and a silicone quaternary ammonium salt.

2. The oil-permeable and water-blocking film pre-pad according to claim 1, characterized in that: The solvent is any one of N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, triethyl phosphate, dimethylaminoethanol, dichloroethane, and acetone.

3. The oil-permeable and water-blocking film pre-pad according to claim 1, characterized in that: The porogen is any one or more of ethylene glycol, polyvinyl pyrrolidone, glycerol, polyethylene glycol, ethylene glycol, ethanol, propanol, butanol, and water.

4. A method for preparing the oil-permeable and water-blocking film pre-pad according to any one of claims 1 to 3, characterized in that: The following steps are involved: First, the solvent, the membrane body and the porogen are uniformly mixed at 40-120° C. to obtain a mixed solution 1; After the mixed solution 1 is cooled to room temperature, the hydrophobic agent is added, and then mixed uniformly at 30-60° C. to obtain a mixed solution 2; The second mixed solution is kept at a constant temperature of 40-60° C. for 24-36 hours to obtain the oil-permeable and water-blocking film pre-fluid.

5. An oil-permeable and water-blocking film fracturing fluid, characterized in that: The invention comprises 1%-20% of a pre-pad liquid and 80%-99% of a sand-carrying liquid, wherein the pre-pad liquid is the oil-permeable and water-blocking film pre-pad liquid according to any one of claims 1 to 3.

6. The oil-permeable and water-blocking film fracturing fluid according to claim 5, characterized in that: The sand-carrying fluid comprises 980-999 parts of a water-based fracturing fluid and 1-20 parts of an inorganic salt.

7. The oil-permeable and water-blocking film fracturing fluid according to claim 6, characterized in that: The water-based fracturing fluid is slick water fracturing fluid or guar gum fracturing fluid; the inorganic salt is one or more of sodium chloride, lithium chloride, phosphoric acid, ammonium chloride, calcium chloride, sodium nitrate, sodium sulfate, sodium bisulfite, and calcium sulfate.

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