Crack plugging agent for oil and gas reservoirs as well as preparation method and application of crack plugging agent

Abstract

The invention provides a crack plugging agent for oil and gas reservoirs and a preparation method and application thereof.The crack plugging agent comprises specific parts of oil, oil soluble resin, a curing agent, a stabilizer, fibers, an emulsifier and water. The oil-soluble resin reinforced oil and water added with the curing agent can form a water-in-oil emulsion, and meanwhile, the curing agent can be uniformly dispersed in a water phase of the water-in-oil emulsion, so that the oil-soluble resin has a porous structure after being finally cured, and can be used for plugging cracks of deep high-temperature oil and gas reservoirs; the recovery efficiency of the oil and gas reservoir is effectively improved, and the method has important research significance.

Description

Technical Field

[0001] The present invention belongs to the technical field of plugging agents, and in particular relates to a fracture plugging agent for oil and gas reservoirs, a preparation method thereof and an application thereof. Background Art

[0002] Research has found that low-permeability and unconventional oil and gas reservoirs account for more than 90% of the proven reserves of oil and gas reservoirs and have become the main body of oil and gas field development. The current main development method is fracturing development, which will inevitably produce a large number of artificial fractures. Combined with the original natural fractures, it increases the difficulty of water control and causes inefficient and ineffective circulation of injected water. It is difficult to effectively displace a large amount of underground crude oil, and the development and production costs of oil fields are high and the benefits are low. Profile adjustment and water plugging are one of the important means to solve the inefficient and ineffective circulation of water injection in water-driven oilfields and improve the recovery rate of water-driven development.

[0003] CN116218491A discloses a hydrogel plugging agent, a method for preparing the hydrogel plugging agent, and a water-based drilling fluid. The hydrogel plugging agent is composed of the following raw materials: 40-50 parts of a clay mineral, 10-20 parts of a bentonite modifier containing aluminum borate whiskers, 10-20 parts of modified nanographene, 2-5 parts of a lubricant, 2-5 parts of a tackifier, 2-6 parts of a coupling agent, and 55-75 parts of deionized water. The hydrogel plugging agent provided by the invention is prepared by combining clay minerals, lubricants, and tackifiers with deionized water, aluminum borate whiskers, and modified nanographene. The prepared product has excellent plugging effect and stable plugging effect under high temperature and high pressure.

[0004] However, both inorganic systems represented by cement and organic systems represented by polymer gels, including the above-mentioned invention, can cause damage to oil and gas reservoirs during use, especially to the development of gas reservoirs. Moreover, they have limited ability to seal cracks and lack sand control functions, and their field applications still have certain limitations.

[0005] Therefore, in order to solve the above technical problems, it is urgent to develop a water plugging agent with excellent plugging performance for crack plugging in deep high-temperature oil and gas reservoirs. Summary of the Invention

[0006] In response to the deficiencies of the prior art, the present invention aims to provide a fracture plugging agent for oil and gas reservoirs, as well as a preparation method and application thereof. The fracture plugging agent is an oil-in-water emulsion formed by oil reinforced with a soluble resin and water added with a curing agent. The curing agent is uniformly dispersed in the aqueous phase of the oil-in-water emulsion. After curing, the oil-soluble resin will cause the resulting fracture plugging agent to have a porous structure. The fracture plugging agent can be used for fracture plugging in deep, high-temperature oil and gas reservoirs, effectively improving the recovery rate of the oil and gas reservoirs, and has important research significance.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a fracture plugging agent for oil and gas reservoirs, wherein the fracture plugging agent comprises the following components in parts by weight:

[0009]

[0010] The amount of the oil may be 0.42 parts by weight, 0.44 parts by weight, 0.46 parts by weight, 0.48 parts by weight, 0.50 parts by weight, 0.52 parts by weight, 0.54 parts by weight, 0.56 parts by weight, or 0.58 parts by weight.

[0011] The oil-soluble resin may be in an amount of 0.32 parts by weight, 0.34 parts by weight, 0.36 parts by weight, or 0.38 parts by weight.

[0012] The curing agent may be in an amount of 0.022 parts by weight, 0.024 parts by weight, 0.026 parts by weight, or 0.028 parts by weight.

[0013] The stabilizer may be in an amount of 0.022 parts by weight, 0.024 parts by weight, 0.026 parts by weight, or 0.028 parts by weight.

[0014] The fiber may be present in an amount of 0.05 parts by weight, 0.06 parts by weight, 0.07 parts by weight, 0.08 parts by weight, or 0.09 parts by weight.

[0015] The emulsifier may be 0.022 parts by weight, 0.024 parts by weight, 0.026 parts by weight, 0.028 parts by weight, 0.03 parts by weight, 0.032 parts by weight, 0.034 parts by weight, 0.036 parts by weight, or 0.038 parts by weight.

[0016] The amount of water may be 0.62 parts by weight, 0.64 parts by weight, 0.66 parts by weight, 0.68 parts by weight, 0.70 parts by weight, 0.72 parts by weight, 0.74 parts by weight, 0.76 parts by weight, or 0.78 parts by weight.

[0017] The fracture plugging agent provided by the present invention includes specific proportions of oil, oil-soluble resin, curing agent, stabilizer, fiber, emulsifier and water. By selecting and matching the above seven materials, the oil reinforced by the oil-soluble resin can form an oil-in-water emulsion with water added with the curing agent. At the same time, the curing agent is uniformly dispersed in the aqueous phase of the oil-in-water emulsion. When used at formation temperature, the oil-soluble resin will form a porous network solidified structure under the action of the curing agent in the aqueous phase, which can convert difficult-to-block fracture spaces into easily controllable porous medium spaces. The size of the connected pores can be controlled by parameters such as the oil-water ratio, the rotation speed during preparation, and the fiber dosage, thereby controlling the ultimate permeability. This can effectively plug fractures in oil and gas fields and improve the development effect of oil and gas fields, and has important research significance.

[0018] Preferably, the emulsion type of the crack plugging agent is a water-in-oil emulsion.

[0019] Preferably, the oil includes any one of kerosene, white oil, heavy oil or crude oil, or a combination of at least two of them, and more preferably heavy oil and / or crude oil.

[0020] Preferably, the oil-soluble resin includes industrial resin, more preferably epoxy resin and / or phenolic resin.

[0021] Preferably, the curing agent includes any one of ethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine or m-phenylenediamine, or a combination of at least two thereof, and more preferably ethylenediamine and / or diethylenetriamine.

[0022] Preferably, the stabilizer comprises dibutyl phthalate and / or dioctyl phthalate, more preferably dioctyl phthalate;

[0023] Preferably, the fibers include any one of viscose fibers, acetate fibers, cuprammonium fibers, cellulose fibers, starch fibers, polyester fibers, polyamide fibers or polyvinyl alcohol fibers, or a combination of at least two thereof, and more preferably cellulose fibers and / or polyester fibers.

[0024] Preferably, the emulsifier comprises any one of alkylphenol polyoxyethylene ether, polyoxyethylene castor oil, fatty alcohol polyoxyethylene ether, sorbitan monolaurate, polyoxyethylene sorbitan monolaurate or polyurethane, or a combination of at least two thereof, more preferably sorbitan monolaurate and / or polyurethane;

[0025] Preferably, the water comprises any one of clean water, treated produced water or river water, or a combination of at least two of them, and is more preferably clean water.

[0026] In a second aspect, the present invention provides a method for preparing the crack sealing agent according to the first aspect, the preparation method comprising the following steps:

[0027] (1) mixing oil, oil-soluble resin and stabilizer to obtain an oil phase; mixing fiber, curing agent and water to obtain a water phase;

[0028] (2) Mixing the oil phase and the water phase obtained in step (1) to obtain the crack plugging agent.

[0029] In a third aspect, the present invention provides a use of the fracture plugging agent according to the first aspect, wherein the use includes plugging fractures in oil and gas reservoirs.

[0030] Preferably, the oil and gas reservoir comprises a deep high-temperature oil and gas reservoir, which refers to an oil and gas reservoir with a depth of more than 3500m and a temperature of more than 120°C.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The initial state of the fracture plugging agent provided by the present invention is an oil-in-water emulsion. When used at formation temperature, the oil-soluble resin will form a porous network solidified structure under the action of the curing agent in the water phase, which can turn the difficult-to-block fracture space into an easily controllable porous medium space. The size of the connected pores can be controlled by controlling parameters such as the oil-water ratio, the rotation speed during preparation, and the fiber dosage, thereby controlling the ultimate permeability. Specifically, the initial setting time of the fracture plugging agent provided by the present invention is adjustable from 6 to 24 hours, which can ensure that the fracture plugging agent has sufficient preparation and injection time, and has strong plugging ability, with a plugging rate of 98.2 to 99.5%. It also has good scour resistance. After plugging, the core permeability does not change even if 50 times the pore volume of water is injected.

[0033] (2) At the same time, the fracture plugging agent provided by the present invention can selectively enter the fracture space. By increasing the viscosity of the fracture plugging agent, it has the advantages of good viscoelasticity and is easy to selectively enter and fill the fracture space, and will not enter the medium and low permeability reservoirs, so it has little damage to the low permeability oil-bearing strata;

[0034] (3) Specifically, the viscosity of the crack plugging agent provided by the present invention can reach 2.8×10 4 ~10.4×10 4 mPa·s (shear rate 1s -1 , 75℃), and the viscoelasticity G'>2×10 4 Pa, has very good rheological properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a graph showing the periodic variation of the storage modulus of the crack plugging agent provided in Example 1 at different temperatures;

[0036] Figure 2 This is a diagram showing the periodic variation of the loss modulus of the crack plugging agent provided in Example 1 at different temperatures. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0038] Unless otherwise specified, the raw materials involved in the specific embodiments of the present invention are conventional materials in the field and can be purchased. Unless otherwise specified, the equipment and instruments used in the specific embodiments of the present invention are conventional equipment and instruments in the field.

[0039] Example 1

[0040] A fracture plugging agent for oil and gas reservoirs, comprising the following components in parts by weight:

[0041]

[0042] Among them, the oil-soluble resin is epoxy resin, purchased from (Baling Petrochemical, E44), the stabilizer is dioctyl phthalate, the curing agent is ethylenediamine, the fiber is cellulose fiber, and the emulsifier is sorbitan monolaurate and polyurethane with a mass ratio of 8:2 (purchased from (Liaoning Jinzhou Kangtai, NP-4));

[0043] The preparation method of the crack plugging agent provided in this embodiment includes the following steps:

[0044] (1) Crude oil, oil-soluble resin and stabilizer are mixed to obtain an oil phase; fiber, curing agent and clean water are mixed to obtain a water phase;

[0045] (2) Mixing the oil phase and the water phase obtained in step (1) to obtain a water-in-oil crack plugging agent.

[0046] Example 2

[0047] A fracture plugging agent for oil and gas reservoirs, comprising the following components in parts by weight:

[0048]

[0049]

[0050] Among them, the oil-soluble resin is epoxy resin, purchased from Baling Petrochemical, E44, the stabilizer is dioctyl phthalate, the curing agent is ethylenediamine, the fiber is cellulose fiber, and the emulsifier is sorbitan monolaurate and polyurethane with a mass ratio of 8:2 (purchased from Liaoning Jinzhou Kangtai, NP-4);

[0051] The preparation method of the crack plugging agent provided in this embodiment includes the following steps:

[0052] (1) Crude oil, oil-soluble resin and stabilizer are mixed to obtain an oil phase; fiber, curing agent and clean water are mixed to obtain a water phase;

[0053] (2) Mixing the oil phase and the water phase obtained in step (1) to obtain a water-in-oil crack plugging agent.

[0054] Example 3

[0055] A crack plugging agent for oil and gas reservoirs, comprising the following components in parts by weight:

[0056]

[0057] Among them, the oil-soluble resin is epoxy resin, purchased from (Baling Petrochemical, E44), the stabilizer is dioctyl phthalate, the curing agent is ethylenediamine, the fiber is cellulose fiber, and the emulsifier is sorbitan monolaurate and polyurethane with a mass ratio of 8:2 (purchased from Liaoning Jinzhou Kangtai, NP-4);

[0058] The preparation method of the crack plugging agent provided in this embodiment includes the following steps:

[0059] (1) Crude oil, oil-soluble resin and stabilizer are mixed to obtain an oil phase; fiber, curing agent and clean water are mixed to obtain a water phase;

[0060] (2) Mixing the oil phase and the water phase obtained in step (1) to obtain a water-in-oil crack plugging agent.

[0061] Example 4

[0062] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that white oil is used instead of crude oil, and other components, amounts and preparation methods are the same as those in Example 1.

[0063] Example 5

[0064] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that phenolic resin is used instead of epoxy resin as the oil-soluble resin, and other components, amounts and preparation methods are the same as those in Example 1.

[0065] Example 6

[0066] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that treated produced water is used instead of clean water, and other components, amounts and preparation methods are the same as those in Example 1.

[0067] Example 7

[0068] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that viscose fiber is used instead of cellulose fiber, and other components, dosages and preparation methods are the same as those in Example 1.

[0069] Comparative Example 1

[0070] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that no stabilizer is added, and other components, amounts and preparation methods are the same as those in Example 1.

[0071] Comparative Example 2

[0072] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that no fiber is added, and other components, amounts and preparation methods are the same as those in Example 1.

[0073] Comparative Example 3

[0074] A fracture plugging agent for oil and gas reservoirs, which differs from Example 1 only in that no oil-soluble resin is added, and other components, amounts and preparation methods are the same as those in Example 1.

[0075] Performance testing:

[0076] (1) Rheological properties:

[0077] The rheological properties of the crack plugging agent provided in Example 1 at different temperatures were tested using a rheometer. The periodic variation of the storage modulus (G') of the crack plugging agent provided in Example 1 at different temperatures was shown in the figure below. Figure 1 As shown, the periodic variation diagram of the loss modulus (G") of the crack plugging agent provided in Example 1 at different temperatures is shown in FIG. Figure 2 As shown;

[0078] according to Figure 1 and Figure 2It can be seen that the fracture plugging agent provided in Example 1 has excellent rheological properties. Specifically, when the fracture plugging agent provided in Example 1 is subjected to rheological property testing, since it is a water-in-oil emulsion, it exhibits both viscous and elastic characteristics. The storage modulus (G') characterizes the elastic effect of the fluid, and the loss modulus (G") characterizes the viscous effect of the fluid. At temperatures of 25°C, 50°C, and 75°C, the fracture plugging agent provided in Example 1 has good elasticity and viscosity, indicating that it has good injection selectivity, can preferentially enter fracture channels in the formation to produce plugging, is less likely to enter medium and low permeability reservoirs, and is less likely to cause contamination.

[0079] (2) Sealing performance:

[0080] Natural carbonate rock cores were cut and cracked using a high-pressure water jet. The cracked cores were placed in a core holder. By changing the confining pressure, the core crack widths and the final permeability of the cores could be varied. The confining pressure was set to 10 MPa, and clean water was used as the displacement fluid. The cracked cores were placed in a core holder and the flow rate was 0.5 mL min. -1 Under the conditions of , 2PV of crack plugging agent was injected, and then 20PV of clean water was injected to conduct core plugging experiments to evaluate the performance of the plugging agent. The experimental temperature was 120°C. The crack plugging agents provided by Examples 1 to 7 and Comparative Examples 1 to 3 were tested according to the above test method. The test results are shown in Table 1:

[0081] Table 1

[0082]

[0083] According to the data in Table 1, we can see that:

[0084] The fracture plugging agent provided by the present invention has excellent sealing performance. Specifically, when the fracture plugging agent provided by the present invention is injected into the core as an oil-in-water emulsion, due to the effect of temperature, at the oil-water interface of the emulsion microspheres, the curing agent in the water phase gradually solidifies the resin in the oil phase, ultimately forming a porous, organic three-dimensional structure. This can significantly reduce the conductivity of the fractures and has excellent water blocking ability (water phase blocking rate greater than 98.2%).

[0085] Among them, compared with Example 1, the crack plugging agent provided in Comparative Example 2 has a lower water phase plugging rate because no stabilizer is added, the crack plugging agent provided in Comparative Example 3 has a lower water phase plugging rate because no fiber is added, and the crack plugging agent provided in Comparative Example 3 has a lower water phase plugging rate because no oil-soluble resin is added, indicating that the plugging effect is poor.

[0086] The applicant states that while the present invention uses the aforementioned embodiments to illustrate a fracture plugging agent for oil and gas reservoirs, its preparation method, and its application, the present invention is not limited to the aforementioned process steps, nor does it necessarily rely on the aforementioned process steps for implementation. Persons skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A crack plugging agent for oil and gas reservoirs, characterized in that: The crack sealing agent comprises the following components in parts by weight:

2. The crack sealing agent according to claim 1, characterized in that The emulsion type of the crack sealing agent is a water-in-oil emulsion.

3. The crack sealing agent according to claim 1 or 2, characterized in that: The oil includes any one of kerosene, white oil, heavy oil or crude oil, or a combination of at least two of them.

4. The crack sealing agent according to any one of claims 1 to 3, characterized in that The oil-soluble resin includes industrial resin, preferably epoxy resin and / or phenolic resin.

5. The crack sealing agent according to any one of claims 1 to 4, characterized in that: The curing agent includes any one of ethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine or m-phenylenediamine, or a combination of at least two thereof, preferably ethylenediamine and / or diethylenetriamine.

6. The crack sealing agent according to any one of claims 1 to 5, characterized in that: The stabilizer includes dibutyl phthalate and / or dioctyl phthalate, preferably dioctyl phthalate; Preferably, the fibers include any one of viscose fibers, acetate fibers, cuprammonium fibers, cellulose fibers, starch fibers, polyester fibers, polyamide fibers or polyvinyl alcohol fibers, or a combination of at least two thereof, and more preferably cellulose fibers and / or polyester fibers.

7. The crack sealing agent according to any one of claims 1 to 6, characterized in that: The emulsifier includes any one of alkylphenol polyoxyethylene ether, polyoxyethylene castor oil, fatty alcohol polyoxyethylene ether, sorbitan monolaurate, polyoxyethylene sorbitan monolaurate or polyurethane, or a combination of at least two thereof, preferably sorbitan monolaurate and / or polyurethane; Preferably, the water comprises any one of clean water, treated produced water or river water, or a combination of at least two of them, and is more preferably clean water.

8. A method for preparing the crack sealing agent according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) mixing oil, oil-soluble resin and stabilizer to obtain an oil phase; mixing fiber, curing agent and water to obtain a water phase; (2) Mixing the oil phase and the water phase obtained in step (1) to obtain the crack plugging agent.

9. Use of the crack plugging agent according to any one of claims 1 to 7, characterized in that: The applications include sealing fractures in oil and gas reservoirs.

10. The use according to claim 9, characterized in that The oil and gas reservoirs include deep high-temperature oil and gas reservoirs.

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