Co 2 flooding responsive channel blocking agent, preparation method therefor and use thereof

Abstract

A CO2 flooding responsive channel blocking agent, a preparation method therefor and a use thereof. Based on the total weight of the CO2 flooding responsive channel blocking agent being 100%, the agent comprises 0.3-2 wt% of a geminal amine, 1-5 wt% of an organic tertiary amine, 0.3-1 wt% of a nano-enhancer, and the remainder is water. The CO2 flooding responsive channel blocking agent system does not contain polymer components, has a low system initial viscosity of less than 6 mPa·s, and has good injection performance. After gelation in response to CO2, the viscosity reaches over 100 Pa·s under zero shear rate conditions, and the viscosity reaches more than 450 mPa·s under a shear rate of 170s-1. The agent can effectively plug deep fractures and / or large pores in a reservoir, expand the sweep coefficient of CO2 in the reservoir, and increase the CO2 flooding recovery rate. It also has excellent temperature resistance, and is suitable for reservoir temperatures up to 120°C.

Description

A CO2 flooding responsive channeling blocking agent and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 25, 2024, with application number 202410108749.1 and invention name “A CO2-driven responsive sealing agent, its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The invention relates to a CO2 flooding responsive channeling blocking agent and a preparation method and application thereof, belonging to the technical field of CO2 flooding enhanced oil recovery. Background Art

[0003] With the continuous development of the oil industry, there are fewer and fewer conventional oil fields that can be exploited. The exploitation of unconventional oil has received more and more attention and has become an important oil replacement resource. However, the development of low-permeability unconventional oil fields faces problems such as the difficulty in establishing effective displacement through water injection development and the rapid decline in output from natural energy development.

[0004] As a displacement medium, CO2 in its supercritical state exhibits low viscosity, high density, high diffusion coefficient, and high solubility. It also exhibits excellent injectability, causing crude oil to expand in volume, acting as a dissolution gas drive. It also reduces crude oil viscosity, improves mobility, reduces / eliminates interfacial tension, and enhances oil recovery efficiency. However, CO2 is susceptible to viscous fingering and gravity differentiation in heterogeneous reservoirs, reducing sweep efficiency and leading to premature gas channeling, resulting in significantly lower-than-expected enhanced oil recovery. Therefore, CO2 channeling control technology has become a key research area within the supporting technologies for CO2 flooding.

[0005] Currently, CO2 gas channeling control mainly adopts methods such as changing the injection method, optimizing the injection medium, and injecting chemical plugging agents. Among them, changing the injection method is mainly divided into water-gas alternation and water-gas co-injection. It is generally ineffective for heterogeneous reservoirs and causes serious corrosion of wellbores and pipelines. The main methods for optimizing the injection medium are CO2 foam technology and CO2 thickening technology. CO2 foam technology injects foaming agents and CO2 into the reservoir to generate foam and increase fluid flow resistance, thereby achieving the purpose of controlling gas channeling. However, this method is not effective in fractured reservoirs with large permeability differences. It also faces many problems such as poor stability of CO2 foam and harsh injection conditions. CO2 thickening technology achieves the purpose of gas channeling control by directly thickening the CO2 gas to improve the mobility ratio of CO2 to formation fluid. However, research on this method is still immature and the cost is very high. The method of injecting chemical plugging agents mainly uses polymer gel for plugging. This polymer gel can effectively block the near-wellbore high permeability zone with high plugging strength. However, most polymer gels are not acid-resistant, resulting in a short plugging period. The initial viscosity of the system is high, and the injection performance is poor. It cannot effectively block the deep oil reservoir. CO2 can easily bypass and break through. At the same time, polymer gel is difficult to degrade, which can easily cause damage to the reservoir matrix and environmental hazards.

[0006] To this end, research on CO2-responsive channeling-blocking agents has gradually become a hot topic. These agents have a low initial viscosity, which increases significantly upon contact with CO2 and can be restored by injecting nitrogen or other non-acidic gases. They also offer excellent injection performance, deep plugging capabilities, and are harmless to the reservoir matrix. While CO2-responsive channeling-blocking agents currently used in this field possess these advantages, they also suffer from numerous drawbacks, such as poor temperature resistance, low plugging strength, and the hydrophobically modified polyacrylamide they use, which can permanently damage the reservoir matrix.

[0007] In summary, the gel-type channeling sealants currently used in this field have problems such as poor injectivity, near-wellbore plugging, and easy damage to the reservoir matrix and environmental hazards. The currently used CO2 flooding responsive channeling sealants have poor temperature resistance and low plugging strength. In addition, the system also contains artificial polymers (generally polyacrylamide polymers), which can cause permanent damage to the reservoir.

[0008] Therefore, providing a new type of CO2 flooding responsive channeling blocking agent and its preparation method and application has become a technical problem that needs to be solved urgently in this field.

[0009] Summary of the Invention

[0010] In order to solve the above-mentioned shortcomings and deficiencies, one object of the present invention is to provide a CO2 flooding responsive channeling blocking agent.

[0011] Another object of the present invention is to provide a method for preparing the above-mentioned CO2 flooding responsive channeling blocking agent.

[0012] Another object of the present invention is to provide the use of the above-mentioned CO2 flooding responsive channeling blocking agent as a channeling blocking agent or a profile control and water plugging agent in oil field exploitation.

[0013] In order to achieve the above objectives, in one aspect, the present invention provides a CO2 flooding responsive channeling blocking agent, wherein, based on the total weight of the CO2 flooding responsive channeling blocking agent being 100%, the agent comprises:

[0014] 0.3-2 wt% of gemini amine, 1-5 wt% of organic tertiary amine, 0.3-1 wt% of nano-reinforcement agent and the balance of water.

[0015] As a specific embodiment of the CO2 flooding responsive sealing agent described above in the present invention, the gemini amine includes dimethylene-1,2-bis(dodecyldimethylammonium bromide), dimethylene-1,2-bis(tetradecyldimethylammonium bromide), N,N'-bislauroylethylenediamine sodium diacrylate and N,N-bis(N-methyl, N-isopropyl alcohol C 12 -C 18 Acyl) C6-C 12 One or more combinations of alkylamines, wherein N,N-di(N-methyl, N-isopropanol) 12 -C 18 Acyl) C6-C 12 The structural formula of alkylamine is shown below:

[0016] Among them, R1 is C6-C 12 Alkyl;

[0017] R2 is C 12 -C 18 of acyl.

[0018] As a specific embodiment of the CO2 flooding responsive sealing agent described above, wherein R1 is C6-C 12 The normal alkyl group;

[0019] R2 is C 12 -C 18 of the normal acyl group.

[0020] The above-mentioned gemini amine used in the present invention can be obtained commercially or prepared by conventional methods.

[0021] Compared with the existing conventional channeling agent system that only uses a single organic tertiary amine, the addition of a gemini amine having the above structure to the CO2 flooding responsive channeling agent of the present invention can improve the temperature resistance and gel strength.

[0022] As a specific embodiment of the CO2 flooding responsive sealing agent described above, the N,N-di(N-methyl, N-isopropanol) 12 -C 18 Acyl) C6-C 12 Methods for synthesizing alkylamines include:

[0023] Step (a): C6-C 12 The alkylamine was dissolved in anhydrous ethanol, heated in a water bath to 60-70°C, and an anhydrous ethanol solution of epichlorohydrin was added. The reaction was refluxed for 6-9 hours (preferably 8 hours), and then cooled, crystallized, and filtered to obtain the intermediate product, namely N,N-bis(1-chloro-2-propanol)C6-C 12 Alkylamines;

[0024] Step (b): Take N, N-bis (1-chloro-2-propanol) C6-C 12 Alkylamine was dissolved in acetone and N-methyl C 12 -C 18 Amide and strong base catalyst, react and reflux for 14-18h (preferably 16h), then remove acetone to obtain a solid product, and then wash and dry the solid product to obtain the gemini amine;

[0025] Among them, C6-C 12 Alkylamine, epichlorohydrin, N,N-bis(1-chloro-2-propanol)C6-C 12 Alkylamine and N-methyl C 12 -C 18 The molar ratio of amide is 1:2.0-2.2:1:1.8-2.0.

[0026] In the present invention, in step (a) of the method for synthesizing geminiamine, the cooling crystallization is cooling crystallization at room temperature.

[0027] In the present invention, in step (b) of the synthesis method of geminiamine, after the reaction is refluxed, the reaction is cooled to 40-50°C in an indoor environment and the solvent, such as acetone, is removed at this temperature under vacuum conditions, followed by washing with anhydrous ethanol (e.g., washing three times), and finally drying at a low temperature of 40-50°C to obtain a solid product.

[0028] In the present invention, the strong base catalyst used in step (b) of the method for synthesizing geminiamine is a conventional substance. An appropriate strong base catalyst can be selected and its dosage adjusted according to actual operational requirements, as long as the catalytic reaction can be achieved. In some embodiments of the present invention, the strong base catalyst can be, for example, sodium hydroxide.

[0029] As a specific embodiment of the CO2 flooding responsive cross-linking blocking agent described above, the organic tertiary amine includes an alkyl tertiary amine or an amide tertiary amine having a longest carbon chain with more than 14 carbon atoms.

[0030] As a specific embodiment of the CO2 flooding responsive sealing agent described above in the present invention, the organic tertiary amine includes one or a combination of hexadecyldimethyl tertiary amine, octadecyldimethyl tertiary amine, disetylmethyl tertiary amine, N-dimethylaminopropyl erucamide and N-dimethylaminopropyl stearamide.

[0031] In one embodiment of the CO2-responsive crosslinking blocking agent described above, the nanoreinforcer comprises a carbon-based nanomaterial. In the CO2-responsive crosslinking blocking agent, the nanoreinforcer is used to improve temperature resistance and gel strength. In some embodiments of the present invention, the carbon-based nanomaterial is a graphene-based material.

[0032] As a specific embodiment of the CO2 flooding responsive cross-linking blocking agent described above in the present invention, based on the total weight of the CO2 flooding responsive cross-linking blocking agent being 100%, it further comprises 0.3-3 wt% of an auxiliary agent.

[0033] In a specific embodiment of the CO2 flooding-responsive channeling blocking agent described above, the auxiliary agent includes one or a combination of sodium oleate, sodium salicylate, and sodium dodecyl sulfate. In the CO2 flooding-responsive channeling blocking agent, the auxiliary agent is used to increase the initial viscosity of the system when plugging high-permeability reservoirs.

[0034] As a specific embodiment of the CO2 flooding responsive sealing agent described above in the present invention, the CO2 flooding responsive sealing agent system does not contain a polymer component, the initial viscosity of the system is low, and its initial viscosity (which is the initial viscosity when no additive is added) is lower than 6mPa·s, and the injection performance is good. After the CO2 response gel is formed, the viscosity under zero shear rate conditions reaches more than 100Pa·s, and the shear rate is 170s -1 Under the condition of high viscosity, the viscosity reaches above 450mPa·s, which can effectively seal deep fractures and / or large pores in the reservoir, expand the CO2 sweep coefficient in the reservoir, and improve the CO2 flooding recovery rate.

[0035] On the other hand, the present invention also provides a method for preparing the above-mentioned CO2 flooding responsive channeling blocking agent, wherein the preparation method comprises:

[0036] Gemini amine and organic tertiary amine are sequentially added to water and mixed evenly, then nano-reinforcement agent is added and mixed evenly, and finally auxiliary agent is added or not added and mixed evenly to obtain the CO2 flooding responsive channeling blocking agent.

[0037] In the above preparation method of the present invention, the uniform mixing can be achieved by stirring.

[0038] In the preparation method described above, whether to add an additive is determined based on the initial viscosity required by the high permeability oil reservoir. If the initial viscosity required by the high permeability oil reservoir is high, such as not less than 30 mPa·s, an additive needs to be added; otherwise, no additive is needed.

[0039] In another aspect, the present invention also provides the use of the above-mentioned CO2 flooding responsive channeling blocking agent as a channeling blocking agent or a profile control and water plugging agent in oil field production.

[0040] As a specific embodiment of the above application of the present invention, the application method includes the following steps:

[0041] The CO2 flooding responsive channeling blocking agent is injected into the oil field, and then CO2 is introduced to cross-link and form a channeling blocking gel.

[0042] As a specific embodiment of the above application of the present invention, the application method further includes: after the blocking gel is formed, injecting non-acidic gas or liquid hydrocarbon into the oil field to remove the blocking gel without damaging the reservoir matrix.

[0043] As a specific embodiment of the above-described application of the present invention, the non-acidic gas includes one or a combination of non-acidic gases such as nitrogen and hydrocarbon gases. In some embodiments of the present invention, the hydrocarbon gas may be, for example, methane or ethane, and the liquid hydrocarbon may be, for example, a long-chain alkane with a carbon number of 5 or more, a cycloalkane, an aromatic hydrocarbon, or a mixture thereof.

[0044] As a specific embodiment of the above-mentioned application of the present invention, the reservoir temperature of the oil field is 60-120°C, that is, the CO2 flooding responsive sealing agent has excellent temperature resistance and is suitable for oil reservoir temperatures as high as 120°C.

[0045] Compared with the prior art, the CO2 flooding responsive channeling blocking agent provided by the present invention can achieve the following beneficial technical effects:

[0046] (1) The CO2 flooding responsive sealing agent does not contain polymer substances. Its main components are small molecule chemical reagents and nanomaterials with surface activity. Therefore, the initial viscosity of the system is low (<6mPa·s), with good injection performance and can reach deep into the reservoir.

[0047] (2) The present invention adds a multi-carbon chain gemini amine substance and a carbon-based nanomaterial to the CO2 flooding responsive sealing agent, and utilizes hydrogen bonding to enhance the structural strength of the system after the response gelation, thereby improving the temperature resistance and shear resistance of the system. Under the conditions of formation temperature and flow shear, the strength of the CO2 response gelation is greatly improved (120°C, 170s -1 , viscosity of more than 450mPa·s), it can effectively block cracks and large-pore gas channeling channels, thus being suitable for deep plugging of fractured reservoirs with large permeability gradients.

[0048] (3) The CO2 flooding responsive sealing agent is a non-polymer gel system that can be removed by injecting non-acidic gas or liquid hydrocarbons without damaging the reservoir matrix. See Figure 3 for details.

[0049] (4) When the CO2 flooding responsive channeling blocking agent is used for CO2 flooding channeling, its above-mentioned characteristics can be used to effectively block deep fractures and / or large pores in the reservoir, selectively block CO2 channeling areas and / or high-concentration areas, and have blocking properties for seepage channels of different scales. It is suitable for deep blocking of fractured oil reservoirs with large permeability differences, and by expanding the sweep coefficient of CO2 in the oil reservoir, it can improve the CO2 flooding recovery rate. The CO2 flooding responsive channeling blocking agent has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] 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 describing the embodiments. Obviously, the drawings described below are 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.

[0051] Figure 1 shows the sealing agent d1 at 60°C and 170S in Test Example 1 of the present invention. -1 Shear viscosity test results under 37°C.

[0052] Figure 2 shows the sealing agent d1 in test example 1 of the present invention at 120°C and 170S -1 Shear viscosity test results under 37°C.

[0053] FIG3 is a graph showing the zero shear viscosity test results of the system after CO2 and N2 are introduced into the channeling blocking agent d1 in Test Example 1 of the present invention.

[0054] FIG4 is a schematic structural diagram of the test experimental device used in Test Examples 2 and 3 of the present invention. DETAILED DESCRIPTION

[0055] It should be noted that the term "comprise" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or apparatus.

[0056] The "range" disclosed in the present invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, a range of 60-120 and 80-110 is listed for a particular parameter, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and the maximum range values ​​listed are 3, 4, and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0057] In the present invention, unless otherwise specified, the numerical range "ab" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed in this invention, and "0-5" is merely an abbreviation for these numerical combinations.

[0058] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0059] In the present invention, unless otherwise specified, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0060] In the present invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method comprising steps (a) and (b) indicates that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method further comprising step (c) indicates that step (c) may be added to the method in any order, for example, the method may comprise steps (a), (b) and (c), or may comprise steps (a), (c) and (b), or may comprise steps (c), (a) and (b), etc.

[0061] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the attached table, drawings and examples. The following embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0062] Geminiamine Examples

[0063] Example 1

[0064] This embodiment provides a geminiamine, denoted as geminiamine A, whose structural formula is shown below:

[0065] Wherein, R1 is n-hexyl;

[0066] R2 is n-dodecanoyl;

[0067] The synthetic method of the geminiamine comprises the following specific steps:

[0068] Step (a): dissolving 0.5 mol of n-hexylamine in anhydrous ethanol, heating the mixture to 60° C. in a water bath, adding an anhydrous ethanol solution containing 1 mol of epichlorohydrin, and refluxing the mixture for 8 hours. Cooling and crystallizing at room temperature, and filtering the mixture, yields an intermediate product, namely, N,N-di(1-chloro-2-propanol)-n-hexylamine;

[0069] Step (b): 0.5 mol of the intermediate product obtained in step a was dissolved in acetone, 1 mol of N-methyldodecanamide and NaOH were added in an oil bath at 70°C, the reaction was refluxed for 16 hours, and the mixture was cooled to 40°C in a room environment and the acetone was removed at this temperature under vacuum conditions. The mixture was then washed three times with anhydrous ethanol and finally dried at low temperature (50°C) to obtain the target product, namely N,N-di(N-methyl, N-isopropanol-n-dodecanoyl)-n-hexylamine.

[0070] Example 2

[0071] This embodiment provides a geminiamine, denoted as geminiamine B, whose structural formula is shown below:

[0072] Wherein, R1 is n-octyl;

[0073] R2 is n-hexadecanoyl;

[0074] The synthetic method of the geminiamine comprises the following specific steps:

[0075] Step (a): dissolving 0.5 mol of n-octylamine in anhydrous ethanol, heating the mixture to 65° C. in a water bath, adding an anhydrous ethanol solution containing 1 mol of epichlorohydrin, and reacting under reflux for 8 h. Cooling and crystallizing at room temperature, and filtering to obtain an intermediate product, namely, N,N-di(1-chloro-2-propanol)-n-octylamine;

[0076] Step (b): 0.5 mol of the intermediate product obtained in step a was dissolved in acetone, 1 mol of N-methylhexadecanoylamide and NaOH were added in an oil bath at 75°C, the reaction was refluxed for 16 hours, and the mixture was cooled to 45°C in a room environment and the acetone was removed at this temperature under vacuum conditions. The mixture was then washed three times with anhydrous ethanol and finally dried at low temperature (50°C) to obtain the target product, namely N,N-di(N-methyl, N-isopropanol-n-hexadecanoyl)-n-octylamine.

[0077] Example 3

[0078] This embodiment provides a geminiamine, denoted as geminiamine C, whose structural formula is shown below:

[0079] Wherein, R1 is n-hexyl;

[0080] R2 is n-octadecanoyl;

[0081] The synthetic method of the geminiamine comprises the following specific steps:

[0082] Step (a): dissolving 0.5 mol of n-hexylamine in anhydrous ethanol, heating the mixture to 60° C. in a water bath, adding an anhydrous ethanol solution containing 1 mol of epichlorohydrin, and refluxing the mixture for 8 hours. Cooling and crystallizing at room temperature, and filtering the mixture, yields an intermediate product, namely, N,N-di(1-chloro-2-propanol)-n-hexylamine;

[0083] Step (b): 0.5 mol of the intermediate product obtained in step a was dissolved in acetone, 1 mol of N-methyloctadecanoylamide and NaOH were added in an oil bath at 75°C, the reaction was refluxed for 16 hours, and the mixture was cooled to 45°C in a room environment and the acetone was removed at this temperature under vacuum conditions. The mixture was then washed three times with anhydrous ethanol and finally dried at low temperature (50°C) to obtain the target product, namely N,N-di(N-methyl, N-isopropanol-n-octadecanoyl)-n-hexylamine.

[0084] Example 4

[0085] This embodiment provides a geminiamine, denoted as geminiamine D, whose structural formula is shown below:

[0086] Wherein, R1 is n-dodecyl;

[0087] R2 is n-dodecanoyl;

[0088] The synthetic method of the geminiamine comprises the following specific steps:

[0089] Step (a): dissolving 0.5 mol of dodecylamine in anhydrous ethanol, heating the mixture to 70° C. in a water bath, adding an anhydrous ethanol solution containing 1 mol of epichlorohydrin, and reacting under reflux for 8 h. Cooling and crystallizing at room temperature, and filtering to obtain an intermediate product, namely, N,N-di(1-chloro-2-propanol)-n-dodecylamine;

[0090] Step (b): 0.5 mol of the intermediate product obtained in step a was dissolved in acetone, 1 mol of N-methyldodecanamide and NaOH were added in an oil bath at 74°C, the reaction was refluxed for 16 hours, and the mixture was cooled to 46°C in a room environment and the acetone was removed at this temperature under vacuum conditions. The mixture was then washed three times with anhydrous ethanol and finally dried at low temperature (50°C) to obtain the target product, i.e., N,N-di(N-methyl, N-isopropanol-n-dodecanoyl)-n-dodecylamine.

[0091] Example 5

[0092] This embodiment provides a geminiamine, denoted as geminiamine E, whose structural formula is shown below:

[0093] Wherein, R1 is n-dodecyl;

[0094] R2 is n-octadecanoyl;

[0095] The synthetic method of the geminiamine comprises the following specific steps:

[0096] Step (a): dissolving 0.5 mol of dodecylamine in anhydrous ethanol, heating the mixture to 70° C. in a water bath, adding an anhydrous ethanol solution containing 1 mol of epichlorohydrin, and reacting under reflux for 8 h. Cooling and crystallizing at room temperature, and filtering to obtain an intermediate product, namely, N,N-di(1-chloro-2-propanol)-n-dodecylamine;

[0097] Step (b): 0.5 mol of the intermediate product obtained in step a was dissolved in acetone, 1 mol of N-methyloctadecanoylamide and NaOH were added in an 80°C oil bath, the reaction was refluxed for 16 hours, and the mixture was cooled to 50°C in a room environment and the acetone was removed at this temperature under vacuum conditions. The mixture was then washed three times with anhydrous ethanol and finally dried at low temperature (50°C) to obtain the target product, namely N,N-di(N-methyl, N-isopropanol-n-octadecanoyl)-n-dodecylamine.

[0098] Example of CO2 flooding responsive channeling blocking agent

[0099] Example 1-1

[0100] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent a, which comprises:

[0101] 2 wt% of geminiamine A, 5 wt% of hexadecyldimethyl tertiary amine, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0102] Example 2-1

[0103] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent b, which comprises:

[0104] 1.5 wt% of geminiamine B, 3 wt% of octadecyldimethyl tertiary amine, 0.5 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0105] Example 3-1

[0106] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent C, which comprises:

[0107] 1 wt% of geminiamine C, 4 wt% of dihexadecylmethyl tertiary amine, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0108] Example 4-1

[0109] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent d1, which comprises:

[0110] 2 wt% of geminiamine D, 2 wt% of N-dimethylaminopropyl stearamide, 1 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0111] Example 4-2

[0112] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent d2, which comprises:

[0113] 2wt% dimethylene-1,2-bis(dodecyldimethylammonium bromide), 2wt% N-dimethylaminopropyl stearamide, 1wt% carbon-based nanomaterial (specifically graphene oxide material) and the balance water.

[0114] Example 4-3

[0115] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent d3, which comprises:

[0116] 1wt% dimethylene-1,2-bis(tetradecyldimethylammonium bromide), 1wt% N,N'-bislauroylethylenediamine sodium diacrylate, 2wt% N-dimethylaminopropyl stearamide, 1wt% carbon-based nanomaterial (specifically graphene oxide material) and the balance water.

[0117] Example 5-1

[0118] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent e1, which comprises:

[0119] 0.3 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.5 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0120] Example 5-2

[0121] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent e2, which comprises:

[0122] 0.3 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials), 1 wt% of sodium oleate and the balance of water.

[0123] Example 5-3

[0124] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent e3, which comprises:

[0125] 0.3 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials), 2 wt% of sodium salicylate and the balance of water.

[0126] Example 5-4

[0127] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent e4, which comprises:

[0128] 0.3 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials), 1 wt% of sodium oleate, 2 wt% of sodium dodecylsulfonate and the balance of water.

[0129] Example 5-5

[0130] This embodiment provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent e5, which comprises:

[0131] 0.3 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials), 0.3 wt% of sodium oleate and the balance of water.

[0132] Comparative Example 1

[0133] This comparative example provides a CO2 flooding responsive channeling blocking agent, denoted as channeling blocking agent f1, which comprises:

[0134] 7 wt% of hexadecyldimethyl tertiary amine, 0.3 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0135] Comparative Example 2

[0136] This comparative example provides a CO2 flooding responsive channeling blocking agent, recorded as channeling blocking agent f2, which comprises:

[0137] 2wt% of geminiamine A, 5wt% of hexadecyldimethyl tertiary amine and the balance of water.

[0138] Comparative Example 3

[0139] This comparative example provides a CO2 flooding responsive channeling blocking agent, recorded as channeling blocking agent f3, which comprises:

[0140] 0.2 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.5 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0141] Comparative Example 4

[0142] This comparative example provides a CO2 flooding responsive channeling blocking agent, recorded as channeling blocking agent f4, which comprises:

[0143] 3 wt% of geminiamine E, 1 wt% of N-dimethylaminopropyl erucamide, 0.5 wt% of carbon-based nanomaterials (specifically graphene oxide materials) and the balance of water.

[0144] Test Example 1

[0145] This test example measures the viscosities of channel blockers a-c, d1-d3, e1-e5, and f1-f4, respectively, and includes the following specific steps:

[0146] CO2 gas (gas flow rate of 1.5 mL / min) was introduced into the channeling blocking agents a-c, d1-d3, e1-e5, and f1-f4, respectively, until the system formed a uniform high-viscosity gel. The system was allowed to stand for the bound bubbles to dissipate, and finally a stable high-viscosity gel system was obtained.

[0147] The 170s flow rate of the above system at 60℃, 80℃, 100℃ and 120℃ was measured by high temperature and high pressure rheometer. - 1 The shear viscosity of the test results is shown in Table 1 and Figures 1-2, wherein the "viscosity before contact" and "viscosity after release" in Figures 1-2 correspond to the "initial viscosity" and "gel viscosity" in the table, respectively;

[0148] At the same time, a zero-shear viscosity test was performed on the channeling agent d1 at a temperature of 120°C, including: introducing CO2 gas (gas flow rate of 1.5 mL / min) into the channeling agent d1, and measuring the change in the zero-shear viscosity of the system over time using a high-temperature and high-pressure rheometer during the introduction of CO2 gas;

[0149] N2 was then introduced into the system (gas flow rate was 1.5 mL / min), and the change in the zero shear viscosity of the system over time was measured using a high-temperature and high-pressure rheometer. The change in the zero shear viscosity of the system before and after the introduction of CO2 and N2 was observed. The test results are shown in Figure 3.

[0150] Table 1 Viscosity test results of CO2 flooding responsive channeling agent (170s -1 Cut)

[0151] As can be seen from Table 1 and Figures 1-2, the CO2-driven responsive sealing agent provided in Examples 1-1 to 5-1 of the present invention, which does not contain additives, has a very low initial viscosity and good injection performance, and is suitable for ultra-low to ultra-low permeability reservoirs. Under temperatures of 60-120°C, the CO2-driven responsive sealing agent can form a shear-resistant high-viscosity gel after responding to CO2, which is beneficial for blocking high-permeability channels such as cracks; in Examples 5-2 to 5-5, after adding additives such as sodium oleate, sodium salicylate, and sodium dodecyl sulfate to the CO2-driven responsive sealing agent, its initial viscosity becomes higher, and it is suitable for medium and high permeability reservoirs, see sealing agent e2, sealing agent e3, sealing agent e4, and sealing agent e5.

[0152] It can also be seen from Table 1 and Figures 1-2 that the gemini amine and carbon-based nano-reinforced materials in the CO2 flooding-responsive sealing agent have a huge impact on the viscosity of the system. The absence of any of these components will cause the viscosity of the sealing agent to drop significantly after gelation, as shown in sealing agents f1 and f2. In addition, too low a concentration of gemini amine will reduce the viscosity of the sealing agent, especially under high temperature conditions, the viscosity of the sealing agent will drop significantly, as shown in sealing agent f3. When the gemini amine concentration is higher than 2wt%, it has little effect on the viscosity of the sealing agent after gelation, but will significantly increase the cost of use, as shown in sealing agent f4.

[0153] From the zero-shear viscosity test results shown in Figure 3, it can be seen that the zero-shear viscosity of the system can reach above 100 Pa·s after the introduction of CO2. After the blocking gel is formed, N2 can be injected into the system to release it without damaging the reservoir matrix.

[0154] Test Example 2

[0155] This test example tests the oil displacement efficiency of the channeling blocking agent d1. The schematic diagram of the test experimental device used is shown in Figure 4. The test steps include:

[0156] ① The treated fractured core is vacuum-saturated with water, and the saturated water quality and porosity data are obtained based on the core quality before and after water saturation.

[0157] ② Place the water-saturated core into holder 1, measure the water flooding permeability, saturate it with oil, and age it for 24 hours. Calculate the oil saturation based on the water output of the saturated oil.

[0158] ③ Inject CO2 gas at a flow rate of 0.5 mL / min and a back pressure of 10 MPa. Record the pressure and produced liquid (gas) volume until the gas breakthrough is complete. Record the pressure and produced liquid (gas) data and calculate the oil displacement efficiency.

[0159] ④ After injecting a 0.1PV isolation plug (clean water, active water, or simulated formation water) at a flow rate of 0.1mL / min, inject a 0.3PV channeling agent d1.

[0160] ⑤ After injecting a 0.1PV isolation plug (clean water, active water, or simulated formation water) at a flow rate of 0.1mL / min, continue to inject CO2 at a flow rate of 0.5mL / min until gas breakthrough occurs. Record the pressure and produced fluid (gas) data and calculate the oil displacement efficiency.

[0161] The relevant parameters of the core used in this test case, the experimental temperature, and the obtained oil displacement efficiency / recovery factor data are shown in Table 2 below.

[0162] Table 2 Single fracture core oil displacement efficiency / recovery test results

[0163] As can be seen from Table 2, the CO2 flooding responsive channeling blocking agent provided in the embodiment of the present invention can significantly improve the recovery rate of CO2 flooding through channeling control. Since the increase in temperature affects the viscosity of the system after gelation, the recovery rate improvement decreases with the increase in experimental temperature.

[0164] Test Example 3

[0165] This test example tests the oil displacement efficiency and diversion rate of the channeling blocking agent d1. The schematic diagram of the test experimental device used is shown in Figure 4. The test steps include:

[0166] ① The treated fractured core and matrix core are vacuum-saturated with water. The saturated water quality and porosity data are obtained based on the core quality before and after water saturation.

[0167] ② Place the water-saturated fractured core and matrix core into holder 1 and holder 2 respectively, measure the water flooding permeability, saturate with oil, and age them for 24 hours. Calculate the oil saturation based on the oil-saturated water output.

[0168] ③ Inject CO2 gas at a flow rate of 0.5 mL / min and a back pressure of 10 MPa. Record the pressure and produced liquid (gas) volume until the gas breakthrough is complete. Record the pressure and produced liquid (gas) data and calculate the oil recovery efficiency and diversion rate.

[0169] ④ After injecting a 0.1PV isolation plug (clean water, active water, or simulated formation water) at a flow rate of 0.1mL / min, inject a 0.3PV channeling agent d1.

[0170] ⑤ After injecting a 0.1PV isolation plug (clean water, active water, or simulated formation water) at a flow rate of 0.1mL / min, continuously inject CO2 at a flow rate of 0.5mL / min until gas breakthrough occurs. Record the pressure and produced liquid (gas) data and calculate the oil displacement efficiency and diversion rate.

[0171] The relevant parameters of the core used in this test case and the obtained oil displacement efficiency / recovery factor and diversion rate data are shown in Table 3 below.

[0172] Table 3 Test results of oil displacement efficiency and diversion rate of single fracture core in parallel with matrix core (experimental temperature is 80℃)

[0173] It can be seen from Table 3 that the CO2 flooding responsive channeling blocking agent provided by the embodiment of the present invention can significantly improve the heterogeneity of the reservoir, thereby expanding the sweep coefficient of CO2 flooding and improving the recovery rate.

[0174] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of patent protection, should still fall within the scope of this patent. Furthermore, the technical features of this invention may be freely combined with one another, with other technical inventions, and with other technical inventions.

Claims

1. A CO2 flooding-responsive channel plugging agent, characterized in that, Based on the total weight of the CO2 flooding-responsive channel plugging agent being 100%, it comprises: 0.3 - 2 wt% of gemini amine, 1 - 5 wt% of organic tertiary amine, 0.3 - 1 wt% of nano enhancer, and the balance being water.

2. The CO2 flooding-responsive channel plugging agent according to claim 1, wherein The gemini amine includes one or a combination of several of dimethylene-1,2-bis(dodecyldimethylammonium bromide), dimethylene-1,2-bis(tetradecyldimethylammonium bromide), N,N'-dilauroyl ethylenediamine diacrylate, and N,N-bis(N-methyl, N-isopropyl C 12 -C 18 -acyl)C6-C 12 alkylamine, wherein N,N-bis(N-methyl, N-isopropyl C 12 -C 18 -acyl)C6-C 12 alkylamine has the following structural formula: Among them, R1 is an alkyl group having 6 to C 12 carbon atoms; R2 is C 12 -C 18 acyl group.

3. The CO2 flooding response type channel plugging agent according to claim 2, wherein The synthesis method of the N,N-bis(N-methyl, N-isopropyl C 12 -C 18 -acyl)C6-C 12 alkylamine includes: Step (a): Dissolve C6-C 12 alkylamine in absolute ethanol, heat it in a water bath to 60-70 °C, add an absolute ethanol solution of epichlorohydrin, and after refluxing for 6-9 h, cool it for crystallization and filter to obtain N,N-bis(1-chloro-2-propanolyl)C6-C 12 alkylamine; Step (b): Take N,N-bis(1-chloro-2-propanol)C6-C 12 alkylamine and dissolve it in acetone. Under the condition of an oil bath at 70 - 80 °C, add N-methyl C 12 -C 18 amide and a strong base catalyst. After reacting under reflux for 14 - 18 h, remove acetone to obtain a solid product, and then wash and dry the solid product to obtain the gemini amine; Among them, C6-C 12 alkylamine, epichlorohydrin, N,N-bis(1-chloro-2-propanol) C6-C 12 alkylamine and N-methyl C 12 -C 18 The molar ratio of the amide is 1:2.0 - 2.2:1:1.8 - 2.

0.

4. The CO2 flooding-responsive plugging agent according to claim 1, wherein The organic tertiary amine includes alkyl tertiary amine or amide-based tertiary amine with the longest carbon chain having more than 14 carbon atoms.

5. The CO2 flooding response type channel plugging agent according to claim 4, wherein, The organic tertiary amine includes one or a combination of cetyl dimethyl tertiary amine, stearyl dimethyl tertiary amine, bishexadecyl methyl tertiary amine, N-dimethylaminopropyl erucamide, and N-dimethylaminopropyl stearamide.

6. The CO2 flooding responsive plugging agent according to claim 1, wherein The nano enhancer includes carbon-based nanomaterials.

7. The CO2 flooding-responsive channel plugging agent according to any one of claims 1-6, characterized in that, Based on the total weight of the CO2 flooding-responsive channel plugging agent being 100%, it further comprises 0.3 - 3 wt% of an auxiliary agent.

8. The CO2 flooding-responsive plugging agent according to claim 7, wherein, The auxiliary agent includes one or a combination of sodium oleate, sodium salicylate, and sodium dodecyl sulfonate.

9. The CO2 flooding-responsive channel plugging agent according to any one of claims 1-6, characterized in that, The initial viscosity of the CO2-responsive plugging agent is less than 6 mPa·s, and its viscosity reaches more than 100 Pa·s under zero shear rate conditions after gelling in response to CO2. Under the condition of a shear rate of 170 s -1 , the viscosity reaches more than 450 mPa·s.

10. The preparation method of the CO2 flooding responsive plugging agent according to any one of claims 1-9, characterized in that, The preparation method includes: Adding gemini amine and organic tertiary amine to water in sequence and mixing evenly, then adding the nano enhancer and mixing evenly, and finally adding or not adding the auxiliary agent and mixing evenly to obtain the CO2 flooding-responsive channel plugging agent.

11. Use of the CO2 flooding-responsive channel plugging agent according to any one of claims 1 - 9 as a channel plugging agent or profile control and water shutoff agent in oilfield exploitation.

12. The application according to claim 11, wherein, The method of the use includes the following steps: Injecting the CO2 flooding-responsive channel plugging agent into the oilfield, and then introducing CO2 for crosslinking to form a channel plugging gel.

13. The application according to claim 12, wherein The method of the use further includes: after forming the channel plugging gel, injecting non-acidic gas or liquid hydrocarbons into the oilfield for removal.

14. The application according to claim 13, wherein The non-acidic gas includes one or a combination of nitrogen and hydrocarbon gas.

15. The application according to any one of claims 11-14, characterized in that, The reservoir temperature of the oilfield is 60 - 120 °C.

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