Polymer gel plugging agent and preparation method thereof

Abstract

The invention discloses a polymer gel plugging agent and a preparation method thereof, the polymer gel plugging agent comprises a main agent, a cross-linking agent and a surfactant, the main agent comprises an oil phase dispersion medium, an instant polymer and a conditioning agent; in addition, the viscosity is greater than 50000 mPa.s. The preparation method comprises the following steps: preparing the main agent according to the component proportion; adding the main agent, the cross-linking agent and the surfactant into water in proportion, and stirring and dissolving at a preset speed to form a polymer solution; and curing the polymer solution at the formation temperature for 120 hours to obtain the polymer gel plugging agent. According to the invention, polyacrylamide and other solid particles are added into an oil phase dispersion medium for uniform dispersion, then a surfactant is added, water is added for dissolution, and formation of'fisheye 'is reduced, so that the concentration of polyacrylamide is increased to 10%, and after a cross-linking agent is added, a plugging agent with higher strength can be formed to plug a high-permeability strip in a stratum.

Description

Technical Field

[0001] The present invention relates to the technical field of profile control and water plugging in oil fields, and particularly relates to a polymer gel plugging agent and a preparation method thereof. Background Art

[0002] Polymer gel plugging agents are widely used in the technical field of profile control and water plugging in oil fields. The main purpose is to block high-permeability zones between oil wells and water wells. Most of the polymers used are polyacrylamide. After adding a crosslinking agent, a three-dimensional network structure gel is formed, which can block the high-permeability zones in the formation. Polyacrylamide is a high-molecular polymer with a molecular weight of up to 25 million. The dissolution principle is that when solid polyacrylamide contacts water, it first swells and then dissolves. If too much is added, the polyacrylamide that first contacts water and then swells will wrap the later products that have not contacted water, thus forming "fish eyes" and causing difficult dissolution. Therefore, the preparation concentration is generally up to 0.4 - 0.6%, and the solution viscosity formed is 1000 - 2000 mPa·s. It is difficult to pump polymers with higher viscosities into the formation. When the concentration of the crosslinking agent is fixed, the viscosity of the polyacrylamide gel is proportional to the concentration. The gel prepared with low-concentration polyacrylamide has a low viscosity and a low plugging strength, which affects the profile control and water plugging effect.

[0003] In Chinese Patent CN20140575761.X "Profile control and water plugging agent for profile control and water plugging in high-temperature and high-salinity oil reservoirs and profile control and water plugging method", the concentration of hydrolyzed polyacrylamide is 0.3 - 0.6%, the crosslinking agent is 0.1 - 0.2%, the stabilizer is 0.1 - 0.2%, the inorganic particle inducer is 3.2 - 4.0%, and the water containing calcium ions is 95 - 96.3%. The concentration of polyacrylamide polymers in this patent is relatively low, and the prepared gel has a low viscosity and a low plugging strength.

[0004] In Chinese Patent CN201811238465.5 "Polyacrylamide-based gel plugging agent and its preparation method and application", the content of acrylamide-based polymers is 0.1 - 2%, the content of urea-based compounds is 0.1 - 2%, the content of water-soluble urea-formaldehyde resin is 0.1 - 2%, and the content of deoxidizer is 0.05 - 1%. In Chinese Patent CN103666418A "A gel profile control and plugging agent", the temperature- and salt-resistant polymer is 0.1 - 6% (molecular weight > 20 million), the crosslinking agent is 0.1 - 6%, the stabilizer is 0.1 - 6%, the iron ion precipitant is 0.1 - 6%, and the oil field field water is 90 - 99.5%. When the molecular weight of the polymer > 20 million and the preparation concentration > 0.8%, it is difficult to dissolve on site.

[0005] Based on this, the existing technology still needs to be improved. Summary of the Invention

[0006] To solve the above technical problems, an embodiment of the present invention provides a polymer gel plugging agent and a preparation method thereof to solve the technical problem that the polymer gel plugging agent in the prior art cannot meet the production requirements.

[0007] To solve the above technical problems, on the one hand, some embodiments of the present invention disclose a polymer gel plugging agent, which includes a main agent, a crosslinking agent, and a surfactant. Among them, the main agent includes an oil-phase dispersion medium, an instant polymer, and a regulator; and the viscosity is greater than 50000 mPa·s.

[0008] In some embodiments, by mass percentage, it includes 0.6-10% of instant polymer; 0.6-10% of crosslinking agent; 0.2-2% of surfactant, and the rest is water.

[0009] In some embodiments, in the main agent, by mass parts, it includes 30-60 parts of oil-phase dispersion medium, 20-40 parts of instant polymer, and 6-18 parts of regulator.

[0010] In some embodiments, the oil-phase dispersion medium is one or a mixture of two of white oil and kerosene.

[0011] In some embodiments, the instant polymer is instant polyacrylamide with a molecular weight of 12 million - 25 million.

[0012] In some embodiments, the regulator is one or a mixture of two of resorcinol, hydroquinone, and catechol.

[0013] In some embodiments, the crosslinking agent is one, two, or a mixture of two or more of phenolic resin, hexamethylenetetramine, formaldehyde, and paraformaldehyde.

[0014] In some embodiments, the surfactant is one or a mixture of two of sodium dodecyl sulfate and alkylphenol polyoxyethylene ether.

[0015] On the other hand, an embodiment of the present invention also discloses a preparation method of the aforementioned polymer gel plugging agent, including:

[0016] Preparing the main agent according to the component ratio;

[0017] Adding the main agent, the crosslinking agent, and the surfactant into water according to the ratio, and stirring and dissolving at a predetermined speed to form a polymer solution;

[0018] Curing the polymer solution at the formation temperature for 120 h to obtain the polymer gel plugging agent.

[0019] In some embodiments, when preparing the polymer solution, it is dissolved at a speed of 125 - 145 revolutions per minute for ten minutes to form a polymer solution with a mass concentration of 0.6 - 10% of instant polymer.

[0020] Adopting the above technical solution, the present invention has at least the following beneficial effects:

[0021] A polymer gel plugging agent provided by the present invention and its preparation method. First, solid particles such as polyacrylamide are added to an oil-phase dispersion medium and uniformly dispersed, then a surfactant is added, and then water is added for dissolution to reduce the formation of "fish eyes", thereby increasing the concentration of polyacrylamide to 10%. After adding a cross-linking agent, a plugging agent with higher strength can be formed to plug high-permeability zones in the formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a process flow chart of a preparation method of a polymer gel plugging agent disclosed in some embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following will further describe in detail the embodiments of the present disclosure in conjunction with the drawings and examples. The detailed description and drawings of the following examples are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms, not limited to the specific embodiments disclosed herein, but including all technical solutions falling within the scope of the claims.

[0025] These embodiments are provided by the present disclosure to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the components of materials, numerical expressions and values described in these embodiments should be interpreted as merely exemplary, rather than as limitations.

[0026] It should be noted that in the description of the present disclosure, unless otherwise specified, the meaning of "a plurality" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate the orientation or positional relationship only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0027] In addition, the "first", "second" and similar terms used in this disclosure do not denote any order, quantity or importance, but are merely used to distinguish different parts. "Vertical" does not mean strictly vertical, but within the allowable error range. "Parallel" does not mean strictly parallel, but within the allowable error range. Words such as "including" or "comprising" mean that the elements before this word cover the elements listed after this word, and do not exclude the possibility of also covering other elements.

[0028] It should also be noted that in the description of this disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected" and "joined" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this disclosure can be understood according to specific circumstances. When it is described that a specific device is located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0029] All terms used in this disclosure have the same meanings as understood by those of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as those, should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense, unless specifically defined as such here.

[0030] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods and devices should be regarded as part of the specification.

[0031] Some embodiments of the present invention disclose a polymer gel plugging agent, which includes a main agent, a crosslinking agent and a surfactant. Among them, the main agent includes an oil-phase dispersion medium, an instant polymer and a regulator; and the viscosity is greater than 50000 mPa·s. In terms of mass percentage content, the content of each component can be: instant polymer 0.6-10%; crosslinking agent 0.6-10%; surfactant 0.2-2%, and the rest is water. In the main agent, in terms of parts by mass, it includes 30-60 parts of oil-phase dispersion medium, 20-40 parts of instant polymer, and 6-18 parts of regulator. The oil-phase dispersion medium is one or a mixture of two of white oil and kerosene. The instant polymer is instant polyacrylamide with a molecular weight of 12 million to 25 million. The regulator is one or a mixture of two of resorcinol, hydroquinone and catechol. The crosslinking agent is one, two or a mixture of more than two of phenolic resin, hexamethylenetetramine, formaldehyde and paraformaldehyde. The surfactant is one or a mixture of two of sodium dodecyl sulfate and alkylphenol polyoxyethylene ether.

[0032] In the embodiments of the present invention, by introducing an oil-phase dispersion medium to uniformly disperse polymer particles, the preparation of a high-concentration polymer can be achieved. The viscosity of the prepared gel plugging agent is >50000 mPa·s, which can effectively plug high-permeability zones in the formation.

[0033] Some embodiments of the present invention disclose a polymer gel plugging agent, which is composed of a gel-forming main agent, a cross-linking agent, and a surfactant. The concentration of the main agent in the prepared plugging agent solution is 0.6-10%, the concentration of the cross-linking agent is 0.6-10%, the concentration of the surfactant is 0.2-2%, and the rest is water.

[0034] The gel-forming main agent is composed of the following components by mass percentage: 30-60 parts of an oil-phase dispersion medium, 20-40 parts of a fast-dissolving polymer, and 6-18 parts of a regulator.

[0035] The oil-phase dispersion medium is one or a mixture of two of white oil and kerosene;

[0036] The fast-dissolving polymer is fast-dissolving polyacrylamide with a molecular weight of (18 million - 25 million);

[0037] The regulator is one or a mixture of two of resorcinol, hydroquinone, and catechol;

[0038] The cross-linking agent is one, two, or a mixture of two or more of phenolic resin, hexamethylenetetramine, formaldehyde, and paraformaldehyde.

[0039] The surfactant is one or a mixture of two of sodium dodecyl sulfate and alkylphenol polyoxyethylene ether;

[0040] The water is tap water or field water in the oilfield.

[0041] As Figure 1 shown, the preparation method is as follows:

[0042] Add the fast-dissolving polymer dry powder and the regulator into the oil-phase dispersion medium in proportion to prepare the gel-forming main agent. Then add the gel-forming main agent, the cross-linking agent, and the surfactant into a certain amount of water in proportion, dissolve at a speed of 135 revolutions per minute for 10 minutes to form a 0.6-10% polymer solution, pour it into a wide-mouth bottle with a stopper, cure at the formation temperature for 120 hours, and measure the viscosity.

[0043] Example 1

[0044] The composition of the gel profile control agent (polymer gel plugging agent) is as follows: fast-dissolving polyacrylamide (molecular weight: 22 million 420 parts of white oil, 60 parts of white oil, 13 parts of regulator, 15 parts of crosslinking agent, 2 parts of surfactant, and the prepared liquid has a viscosity of 420 mPa·s. Add 3323 parts of clear water and stir at 135 rpm for 10 min. The regulator is hydroquinone, the crosslinking agent is phenolic resin, and the surfactant is sodium dodecyl sulfate.

[0045] Take the sample and place it in a stoppered wide-mouth bottle in the laboratory. Observe the gel formation situation in a constant temperature drying oven at 50 °C. It is found through experiments that after turning the wide-mouth bottle over after 120 hours, a flowable gel is formed with a viscosity of 50000 mPa·s.

[0046] The instrument for testing the gel viscosity includes: Brookfield DV-Ⅲ rotational viscometer, No. 4 rotor, and a shear rate of 6 revolutions per minute.

[0047] Example 2

[0048] The gel profile control agent is composed of the following: instant polyacrylamide (molecular weight: 2200×10 4 g / mol) 28 parts, 40 parts of white oil, 15 parts of regulator, 15 parts of crosslinking agent, 2 parts of surfactant, and the prepared liquid has a viscosity of 680 mPa·s. Add 460 parts of clear water and stir at 135 rpm for 10 min. The regulator is resorcinol, the crosslinking agent is paraformaldehyde, and the surfactant is alkylphenol polyoxyethylene ether.

[0049] Take the sample and place it in a stoppered wide-mouth bottle in the laboratory. Observe the gel formation situation in a constant temperature drying oven at 60 °C. It is found through experiments that after turning the wide-mouth bottle over after 120 hours, a gel with a viscosity of 200000 mPa·s is formed.

[0050] The instrument for testing the gel viscosity includes: Brookfield DV-Ⅲ rotational viscometer, No. 4 rotor, and a shear rate of 6 revolutions per minute.

[0051] Example 3

[0052] The gel profile control agent is composed of the following: instant polyacrylamide (molecular weight: 2200×10 4 g / mol) 40 parts, 30 parts of white oil, 13 parts of regulator, 15 parts of crosslinking agent, 2 parts of surfactant, and the prepared liquid has a viscosity of 830 mPa·s. Add 300 parts of clear water and stir at 135 rpm for 10 min. The regulator is a mixture of hydroquinone and catechol (molar ratio 2:1), the crosslinking agent is a mixture of hexamethylenetetramine and formaldehyde (molar ratio 1.2:2), and the surfactant is a mixture of sodium dodecyl sulfate and alkylphenol polyoxyethylene ether (molar ratio 1:1).

[0053] Take the sample and place it in a stoppered wide-mouth bottle in the laboratory. Observe the gel formation situation in a constant temperature drying oven at 70°C. It was found in the test that after 120 hours, the wide-mouth bottle was inverted, and the generated gel had a viscosity of 500000 mPa·s.

[0054] The instrument for testing the gel viscosity includes: Brookfield DV-Ⅲ rotational viscometer, No. 4 rotor, and shear rate of 6 revolutions per minute.

[0055] So far, the embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details well-known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0056] Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or partial technical features can be equivalently replaced without departing from the scope and spirit of the present disclosure. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way.

Claims

1. A polymer gel plugging agent, characterized in that, it comprises a main agent, a crosslinking agent and a surfactant, wherein the main agent comprises an oil-phase dispersion medium, an instant polymer and a regulator; and, the viscosity is greater than 50000 mPa·s.

2. The polymer gel plugging agent according to claim 1, characterized in that, by mass percentage, it comprises 0.6-10% of instant polymer; 0.6-10% of crosslinking agent; 0.2-2% of surfactant, and the rest is water.

3. The polymer gel plugging agent according to claim 1, characterized in that, in the main agent, by mass parts, it comprises 30-60 parts of oil-phase dispersion medium, 20-40 parts of instant polymer, 6-18 parts of regulator.

4. The polymer gel plugging agent according to claim 1, characterized in that, the oil-phase dispersion medium is one or a mixture of two of white oil and kerosene.

5. The polymer gel plugging agent according to claim 1, characterized in that, the instant polymer is instant polyacrylamide with a molecular weight of 12 million - 25 million.

6. The polymer gel plugging agent according to claim 1, characterized in that, the regulator is one or a mixture of two of resorcinol, hydroquinone and catechol.

7. The polymer gel plugging agent according to claim 1, characterized in that, the crosslinking agent is one, two or a mixture of two or more of phenolic resin, hexamethylenetetramine, formaldehyde and paraformaldehyde.

8. The polymer gel plugging agent according to claim 1, characterized in that, the surfactant is one or a mixture of two of sodium dodecyl sulfate and alkylphenol polyoxyethylene ether.

9. The preparation method of the polymer gel plugging agent according to any one of claims 1-8, characterized in that, it comprises: configuring the main agent according to the component ratio; adding the main agent, the crosslinking agent and the surfactant into water according to the ratio, and stirring and dissolving at a predetermined speed to form a polymer solution; curing the polymer solution at the formation temperature for 120 h to obtain the polymer gel plugging agent.

10. The preparation method according to claim 9, characterized in that, when preparing the polymer solution, it is dissolved at a speed of 125-145 revolutions per minute for ten minutes to form a polymer solution with a mass concentration of 0.6-10% of instant polymer.

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