CN116410716A

CN116410716A - Supermolecule gel temporary plugging agent and preparation method thereof

Info

Publication number: CN116410716A
Application number: CN202111661829.2A
Authority: CN
Inventors: 张照阳; 管彬; 鲍晋; 何启平; 尹丛彬; 唐雷; 陈明忠; 孟照海
Original assignee: China National Petroleum Corp; CNPC Chuanqing Drilling Engineering Co Ltd
Current assignee: China National Petroleum Corp; CNPC Chuanqing Drilling Engineering Co Ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-07-11
Anticipated expiration: 2041-12-31
Also published as: CN116410716B

Abstract

The invention provides a supermolecule gel temporary plugging agent and a preparation method thereof, wherein the supermolecule gel temporary plugging agent comprises the following components: beta-cyclodextrin, even-carbon saturated fatty acid, N-Dimethylformamide (DMF), lithium chloride, polyethylene glycol and methylcellulose. The supermolecular gel temporary plugging agent is suitable for stratum at 60-130 ℃, and the mass percentage of each component is 12-20% of beta-cyclodextrin, 5-10% of even-numbered saturated fatty acid, 67-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-10% of polyethylene glycol and 0.5-2% of carboxymethyl cellulose. The beneficial effects of the invention include: the supermolecular gel temporary plugging agent has the characteristics of adjustable stability time, controllable applicable temperature range, high strength, small fluid loss, easy plugging removal and small damage to a rock core, and can realize the shielding temporary plugging of micro cracks and deep cracks.

Description

Supermolecule gel temporary plugging agent and preparation method thereof

Technical Field

The invention belongs to the technical field of temporary plugging agents, and particularly relates to a supermolecule gel temporary plugging agent and a preparation method thereof.

Background

Petroleum and natural gas are the most important fossil fuels in the world today, and petroleum resources are known as industrial blood in China. The unconventional low-permeability oil and gas resources account for about 50%, so the exploitation of the unconventional low-permeability oil and gas resources is very important. As the yield ratio of unconventional low permeability fields becomes higher and higher, fracturing stimulation techniques are becoming the dominant technique for such reservoirs to increase single well yields.

After the conventional low-permeability oil and gas field is subjected to hydraulic fracturing construction, the yield is greatly reduced due to the change of stratum conditions and the limitation of a fracturing process, and repeated fracturing for two times is required to achieve the economic effects of stable yield and yield increase of the oil field. In the repeated fracturing process, the most critical technology is to temporarily plug the original blasthole or crack, press a new crack in a direction different from the original crack, communicate an unused reservoir or an oil layer with low use level, increase the oil drainage area and improve the productivity. Therefore, temporary plugging and channeling prevention are required by using the plugging action of the temporary plugging agent.

The temporary plugging agents have different forms and can be mainly divided into the following categories: particulate temporary blocking agents, fibrous temporary blocking agents, polymer gel temporary blocking agents, and the like. The granular temporary plugging agent has the advantages of strong bearing capacity, low reservoir damage, low price, controllable dissolution time, convenient construction and the like, but if the size of the soluble temporary plugging agent of the injected solid particles is improperly designed, the temporary plugging efficiency can be greatly influenced. The fiber temporary plugging agent has flexibility variability and can be automatically degraded, but has limited pressure bearing capacity. For the use of polymer gel temporary plugging agents, the dosage of the cross-linking agent is difficult, low amounts of cross-linking agent will result in too low a plugging strength, and high dosages will also damage the formation.

The most currently used is a solid particulate temporary plugging agent. But due to its own nature, construction typically requires separate installation of the remote transmitter and manual delivery. Because of the inherent characteristics of the solid temporary plugging agent, the intra-fracture migration distance is short, most of the solid temporary plugging agent is applied to near-wellbore zones, and the solid temporary plugging agent is difficult to convey to the tip of a fracture to shield temporary plugging.

The Chinese patent publication No. CN106833571A discloses a high-pressure-bearing frozen temporary plugging agent and a preparation method thereof, wherein the high-pressure-bearing frozen temporary plugging agent base slurry is prepared by freezing, and comprises the following components in percentage by mass: bentonite, degradable fiber and water, wherein the bentonite is any one or more of sodium bentonite, calcium bentonite and hydrogen bentonite, and the degradable fiber is polylactic acid fiber, polyvinyl alcohol fiber or a mixture of the two. But cannot obtain a fracturing temporary plugging agent with high temporary plugging strength, small filtrate loss, easy plugging removal and small damage to stratum, and cannot improve temporary plugging-steering-plugging removal efficiency.

Disclosure of Invention

The present invention aims to address at least one of the above-mentioned deficiencies of the prior art. For example, it is an object of the present invention to provide a supramolecular gel temporary plugging agent. The invention further aims at providing a preparation method of the supermolecule gel temporary plugging agent.

In order to achieve the above object, according to an aspect of the present invention, there is provided a supramolecular gel temporary plugging agent comprising: beta-cyclodextrin, even numberCarbon saturated fatty acid, N-Dimethylformamide (DMF), lithium chloride, polyethylene glycol and methylcellulose, wherein the even number of carbon saturated fatty acid has 10-16 (C) ₁₀ ～C ₁₆ ) The molecular weight of polyethylene glycol is 400-1000, and the molecular weight of carboxymethyl cellulose is 400-1000.

In an exemplary embodiment of the invention, the supermolecular gel temporary plugging agent is suitable for a stratum with the temperature of 60-130 ℃, and the weight percentage of each component is 12-20% of beta-cyclodextrin, 5-10% of even-numbered saturated fatty acid, 67-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-10% of polyethylene glycol and 0.5-2% of carboxymethyl cellulose.

In an exemplary embodiment of the invention, the supermolecular gel temporary plugging agent is suitable for a stratum with the temperature of 60-90 ℃, and can be prepared from 15-18% of beta-cyclodextrin, 5-7% of even-numbered saturated fatty acid, 68-69% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 8-10% of polyethylene glycol and 0.3-0.7% of carboxymethyl cellulose according to mass percentage.

In an exemplary embodiment of the invention, the supermolecular gel temporary plugging agent is suitable for a stratum with the temperature of 90-110 ℃, and can be prepared from 18-20% of beta-cyclodextrin, 7-9% of even-numbered saturated fatty acid, 67-68% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 4-8% of polyethylene glycol and 0.7-1.5% of carboxymethyl cellulose according to mass percentage.

In an exemplary embodiment of the invention, the supermolecular gel temporary plugging agent is suitable for a stratum with the temperature of 110-130 ℃, and can be prepared from 12-15% of beta-cyclodextrin, 9-10% of even-numbered saturated fatty acid, 69-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-4% of polyethylene glycol and 1.5-2% of carboxymethyl cellulose according to mass percentage.

In an exemplary embodiment of the present invention, the temporary blocking agent for supramolecular gel is in a liquid state at normal temperature, and may undergo a "liquid-gel-liquid state" transition along with an increase in temperature, where the temporary blocking agent is in a liquid state in a first temperature interval, in a second temperature interval, in a gel state, and in a third temperature interval, where the temporary blocking agent for supramolecular gel is in a liquid state, and the first temperature interval is lower than the second temperature interval, and the second temperature interval is lower than the third temperature interval.

The invention also provides a preparation method of the supermolecule gel temporary plugging agent, which comprises the following steps: s1, dissolving lithium chloride in N, N-dimethylformamide, and uniformly mixing to form a hydrogen bond acceptor solvent; s2, dissolving even-numbered saturated fatty acid in a hydrogen bond acceptor solvent, adding beta-cyclodextrin, stirring and dissolving to obtain a first mixed solution; and S3, adding polyethylene glycol and carboxymethyl cellulose into the first mixed solution, and uniformly stirring to form a clear supermolecule gel temporary plugging agent.

In an exemplary embodiment of the present invention, the S3 step may include: s31, sequentially adding polyethylene glycol and carboxymethyl cellulose into the first mixed solution, and uniformly stirring; s32, stirring time is more than 9h, and stirring speed is 290-310 r/min.

In an exemplary embodiment of the present invention, the S2 step may include: even saturated fatty acid is dissolved in hydrogen bond acceptor solvent, and beta-cyclodextrin is added into the solvent at the speed of 0.7-1.2 g/min, stirred and dissolved.

In an exemplary embodiment of the present invention, at least one of the steps S1 to S3 may be performed at normal temperature.

Compared with the prior art, the invention has the beneficial effects that:

1) The supermolecule gel of the invention forms a three-dimensional structure by self-assembly under the action of supermolecules. Because no covalent bond is acted in the gel forming process, the system can respond according to the change of the external condition, and the transition from the solution to the gel to the solution can be realized under the external temperature condition.

2) The supermolecular gel temporary plugging agent has the characteristics of adjustable stability time, controllable applicable temperature range, high strength, small fluid loss, easy plugging removal and small damage to a rock core, and can realize the shielding temporary plugging of micro cracks and deep cracks.

Drawings

Fig. 1 shows a schematic construction diagram of an exemplary embodiment of the present invention.

Fig. 2 (a) shows an infrared spectrum of the supramolecular gel temporary plugging agent of example 1 of the present invention.

Fig. 2 (b) shows an infrared spectrum of the supramolecular gel temporary plugging agent of example 2 of the present invention.

Fig. 2 (c) shows an infrared spectrum of the supramolecular gel temporary plugging agent of example 3 of the present invention.

FIG. 3 (a) shows a scanning electron microscope image of a supermolecular gel temporary plugging agent xerogel of example 1 of the present invention.

FIG. 3 (b) shows a scanning electron microscope image of a supermolecular gel temporary plugging agent xerogel of example 2 of the present invention.

FIG. 3 (c) shows a scanning electron microscope image of a supermolecular gel temporary plugging agent xerogel of example 3 of the present invention.

FIG. 4 shows the X-ray diffraction of the supramolecular gel temporary blocking agent xerogels of examples 1-3 of the present invention.

Fig. 5 (a) shows a gel forming temperature profile of the supramolecular gel temporary plugging agent of example 1 of the present invention.

Fig. 5 (b) shows a gel forming temperature profile of the supramolecular gel temporary plugging agent of example 2 of the present invention.

Fig. 5 (c) shows a gel forming temperature profile of the supramolecular gel temporary plugging agent of example 3 of the present invention.

Fig. 6 shows experimental diagrams of the compatibility of examples 1 to 3 of the present invention.

Fig. 7 (a) shows the fluid loss curve of example 1 of the present invention.

Fig. 7 (b) shows the fluid loss curve of example 2 of the present invention.

Fig. 7 (c) shows the fluid loss curve of example 3 of the present invention.

Fig. 8 shows a diagram of a test rig for the test of the blocking strength according to the invention.

Fig. 9 (a) shows a plot of the test pressure versus injection time for the blocking strength test of example 1 of the present invention.

Fig. 9 (b) shows the plugging strength test experimental pressure versus injection time plot of example 2 of the present invention.

Fig. 9 (c) shows the plugging strength test experimental pressure versus injection time plot of example 3 of the present invention.

FIG. 10 is a graph showing the effect of the guest molecule species of comparative examples B1 to B12 on the gelation temperature of the supramolecular gel temporary plugging agent according to the present invention.

FIG. 11 is a graph showing the effect of the mixing stirring period of comparative examples C1 to C6 on the gelation temperature of the supramolecular gel temporary plugging agent of the present invention.

FIG. 12 is a graph showing the effect of the guest molecule concentration on the gelation temperature of the supramolecular gel temporary plugging agent according to comparative examples D1 to D6 of the present invention.

FIG. 13 is a graph showing the effect of the concentration of host molecules of comparative examples E1 to E6 on the initial gel forming temperature of the supramolecular gel temporary plugging agent of the present invention.

The reference numerals are explained as follows:

1-pressure data collection system, 2-pressure sensor, 3-ISCO pump, 4-first six-way valve, 5-intermediate container, 6-second six-way valve, 7-core holder.

Detailed Description

Hereinafter, a supramolecular gel temporary plugging agent and a method for preparing the same according to the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments. It should be noted that the terms "first," "second," and the like are merely used for convenience of description and for convenience of distinction and are not to be construed as indicating or implying relative importance.

The most currently used is a solid particulate temporary plugging agent. But due to its own nature, construction typically requires separate installation of the remote transmitter and manual delivery. Because of the inherent characteristics of the solid temporary plugging agent, the intra-fracture migration distance is short, and the solid temporary plugging agent is mostly applied to near-wellbore zones (fracture openings or middle), and is difficult to convey to fracture tips for shielding temporary plugging. Based on the method, the transformation from solid particles to phase-changeable liquid is explored, the construction mode is simplified, the temporary plugging agent enters the far end of the crack, and the realization of temporary plugging of the deep part of the crack is significant in improving the construction efficiency, increasing the complexity of the crack and preventing the well channeling.

The main technical conception of the invention is as follows: according to the theory view of supermolecular chemistry, the supermolecular gel temporary plugging agent controllably adjusts the phase transition of sol-gel by introducing additives or changing external conditions, so as to obtain the fracturing temporary plugging agent with high temporary plugging strength, small filtrate loss, easy plugging removal and small damage to stratum, realize fracture diversion and improve temporary plugging-diversion-plugging removal efficiency.

Fig. 1 shows a schematic construction diagram of an exemplary embodiment of the present invention. As shown in fig. 1, (1) is a host molecule, (2) is a guest molecule, (3) is a schematic diagram of chain-like guest and host inclusion, and (4) is self-assembly to form a supramolecular gel. The hydrophobic chain of long-chain fatty acid (hereinafter, also referred to as even-numbered saturated fatty acid) enters the cavity by utilizing the hydrophilic structure of the hydrophobic outer cavity of the inner cavity of beta-cyclodextrin and the hydrogen bond formed by the hydroxyl groups at two end surfaces in the solvent to spontaneously form a head-to-tail structure, so that an interpenetration structure is formed, and the supermolecular gel is formed by self-assembly.

Wherein the host is beta-cyclodextrin, the guest is even-numbered saturated fatty acid, and the solvent is N, N-dimethylformamide.

First exemplary embodiment

In a first exemplary embodiment of the present invention, there is provided a supramolecular gel temporary plugging agent including: beta-cyclodextrin, even-carbon saturated fatty acid, N-Dimethylformamide (DMF), lithium chloride, polyethylene glycol and methylcellulose, wherein the even-carbon saturated fatty acid has 10-16 carbon atoms (C ₁₂ ～C ₁₆ ) The molecular weight of polyethylene glycol is 400-1000, and the molecular weight of carboxymethyl cellulose is 400-1000.

Wherein, the molecular weight refers to the relative molecular weight.

Further, beta-cyclodextrin is mainly composed of a compound having 10 to 16 carbon atoms (C ₁₀ ～C ₁₆ ) Even-numbered saturated fatty acid is used as a guest, lithium chloride is used as an auxiliary agent, N, N-dimethylformamide is used as a solvent, polyethylene glycol (molecular weight 400-1000) is used as a gel temperature regulator, and carboxymethyl cellulose (molecular weight 400-1000) is used as a gel strength regulator.

Wherein, the invention uses beta-cyclodextrin as main body, and the chain length is C ₁₀ ～C ₁₆ Even number carbon saturated fatty acid in the range is taken as a guest, and an auxiliary agent is added to construct supermolecular gel, so that the supermolecular gelThe gel factor forms a three-dimensional structure through intermolecular hydrogen bond, pi-pi accumulation, van der Waals force, static electricity, dipole or solvophobic agent and other supermolecule action self-assembly. Because no covalent bond function exists in the gel forming process, and the non-covalent acting forces such as hydrogen bonds, host-guest inclusion function and the like are superposed, the system can change according to external conditions to realize the response of the change of the state of the system, and therefore, the transition from solution to gel to solution can be realized under a certain external temperature condition.

Li in lithium chloride ⁺ The carbonyl of the molecule is influenced, so that the N, N-dimethylformamide plays a role in constructing the temporary plugging agent of the supermolecule gel.

N, N-dimethylformamide is a hydrogen bond acceptor solvent capable of participating in and promoting the formation of supramolecular gels.

C ₁₀ ～C ₁₆ The saturated fatty acids in the polymer are taken as guest molecules, and all have the capability of gelling.

In an exemplary embodiment of the invention, the supramolecular gel temporary plugging agent is suitable for a stratum at 60-130 ℃, and the amount of each component is 12-20% of beta-cyclodextrin, 5-10% of even-numbered saturated fatty acid, 67-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-10% of polyethylene glycol and 0.5-2% of carboxymethyl cellulose according to mass percentage.

In the embodiment, the concentration of the beta-cyclodextrin accounts for 12-20% of the total mass of the system; the concentration of the long-chain even-numbered saturated fatty acid (C10-C16) accounts for 5-10% of the total mass of the system; the concentration of lithium chloride is 0.5% of the solvent; the dosage of the polyethylene glycol (molecular weight 400-1000) accounts for 2-10% of the total mass of the system; the dosage of the carboxymethyl cellulose (the molecular weight is 400-1000) accounts for 0.5-2% of the total mass of the system.

With the increase of the number of the even-numbered saturated fatty acids, the excessive even-numbered saturated fatty acids cannot be included by the beta-cyclodextrin, so that the excessive even-numbered saturated fatty acids are free and occupy the gaps of the inclusion compound, the regular structure formed by self-assembly of the inclusion compound is destroyed, and the addition amount of the even-numbered saturated fatty acids can have higher gel forming strength within the range of 5% -15%.

In an exemplary embodiment of the invention, the supramolecular gel temporary plugging agent is suitable for a stratum at 60-90 ℃, and can be prepared from 15-18% of beta-cyclodextrin, 5-7% of even-numbered saturated fatty acid, 68-69% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 8-10% of polyethylene glycol and 0.3-0.7% of carboxymethyl cellulose according to mass percentage.

In an exemplary embodiment of the invention, the supramolecular gel temporary plugging agent is suitable for a stratum with the temperature of 90-110 ℃, and can be prepared from 18-20% of beta-cyclodextrin, 7-9% of even-numbered saturated fatty acid, 67-68% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 4-8% of polyethylene glycol and 0.7-1.5% of carboxymethyl cellulose according to mass percentage.

In an exemplary embodiment of the invention, the supramolecular gel temporary plugging agent is suitable for a stratum at 110-130 ℃, and the amount of each component is 12-15% of beta-cyclodextrin, 9-10% of even-numbered saturated fatty acid, 69-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-4% of polyethylene glycol and 1.5-2% of carboxymethyl cellulose according to mass percentage.

In an exemplary embodiment of the invention, the supermolecular gel temporary plugging agent is liquid at normal temperature, and can be converted from liquid state to gel state to liquid state along with the temperature rise.

According to the supermolecular gel temporary plugging agent disclosed by the embodiment of the invention, the transition of liquid state, gel state and liquid state can occur along with the temperature rise, the transition is liquid in a first temperature interval, the transition is gel state in a second temperature interval, the transition is liquid in a third temperature interval, the first temperature interval is lower than the second temperature interval, and the second temperature interval is lower than the third temperature interval.

For example, the above-mentioned supramolecular gel temporary plugging agent suitable for use in a 60 to 90 ℃ stratum is in a liquid state at 60 ℃ or lower, and is in a gel state at 60 to 90 ℃ and is returned to a liquid state at 90 ℃ or higher.

For another example, the supramolecular gel temporary plugging agent suitable for the stratum at 90-110 ℃ is liquid at 90 ℃ or lower, becomes gel at 90-110 ℃ and returns to liquid at 110 ℃ or higher.

For another example, the supramolecular gel temporary plugging agent suitable for the stratum at 110-130 ℃ is in a liquid state at 110 ℃ or lower, becomes in a gel state at 110-130 ℃, and returns to a liquid state at 130 ℃ or higher.

Second exemplary embodiment

In a second exemplary embodiment of the present invention, there is provided a method for preparing a supramolecular gel temporary plugging agent, the method comprising the steps of: s1, dissolving lithium chloride in N, N-dimethylformamide, and uniformly mixing to form a hydrogen bond acceptor solvent; s2, dissolving even-numbered saturated fatty acid in a hydrogen bond acceptor solvent, adding beta-cyclodextrin, stirring and dissolving to obtain a first mixed solution; and S3, adding polyethylene glycol and carboxymethyl cellulose into the first mixed solution, and uniformly stirring to form a clear supermolecule gel temporary plugging agent.

When the stirring time is less than 6 hours, the system gel forming temperature is increased along with the increase of the stirring time; when the stirring time exceeds 6 hours, the system gel forming temperature tends to decrease along with the increase of the stirring time, but the gel forming temperature range tends to be fixed. If the stirring time of the supermolecular gel system is insufficient, the host and guest molecules are not fully included, and the gel forming temperature and the like are unstable. In order to uniformly mix the systems, the main body and the guest body are fully included, and continuous stirring is required to be carried out for more than 9 hours.

Wherein, the stirring speed can be 300r/min.

Wherein the speed may be 1g/min.

In an exemplary embodiment of the present invention, a method for preparing a supramolecular gel temporary plugging agent includes:

A. Dissolving the auxiliary agent in a supermolecule gel solvent at normal temperature and uniformly mixing to form a good hydrogen bond acceptor solvent for standby;

B. c, dissolving the guest molecule sample in the uniform solvent in the step A, slowly adding the weighed host molecule sample at normal temperature, and stirring to uniformly dissolve the host molecule sample for later use;

C. and C, sequentially adding a gel strength regulator and a gel temperature regulator into the solution formed in the step B at normal temperature, and fully stirring at a constant speed for a certain time to form a clear supermolecule gel temporary plugging agent liquid sample with stable performance.

In order to better understand the above-described exemplary embodiments of the present invention, a supramolecular gel temporary plugging agent and a method for preparing the same will be described below in connection with specific examples.

Example 1

The preparation method of the supermolecule gel temporary plugging agent comprises the following steps:

(1) At normal temperature, 0.5% lithium chloride is dissolved in 69% N, N-dimethylformamide and uniformly mixed to form a hydrogen bond acceptor solvent.

(2) 5% of dodecanoic acid is dissolved in a hydrogen bond acceptor solvent, 15% of beta-cyclodextrin is added, and the mixture is stirred and dissolved to obtain a first mixed solution.

(3) Adding 10% of polyethylene glycol and 0.5% of carboxymethyl cellulose into the first mixed solution, and uniformly stirring to form the clear supermolecular gel temporary plugging agent.

Wherein, the main part: beta-cyclodextrin, guest: dodecanoic acid, auxiliary agent: lithium chloride, solvent: n, N-dimethylformamide, gel temperature regulator: polyethylene glycol (molecular weight 400-1000), gel strength regulator: carboxymethyl cellulose (molecular weight 400-1000).

Wherein example 1 is formulation (1).

Example 2

(1) At normal temperature, 0.5% lithium chloride is dissolved in 67.5% N, N-dimethylformamide and uniformly mixed to form a hydrogen bond acceptor solvent.

(2) 9% of dodecanoic acid is dissolved in a hydrogen bond acceptor solvent, 18% of beta-cyclodextrin is added, and the mixture is stirred and dissolved to obtain a first mixed solution.

(3) Adding 4% of polyethylene glycol and 1% of carboxymethyl cellulose into the first mixed solution, and uniformly stirring to form a clear supermolecular gel temporary plugging agent.

Wherein example 2 is formulation (2).

Example 3

(1) At normal temperature, 0.5% lithium chloride is dissolved in 73.5% N, N-dimethylformamide and uniformly mixed to form a hydrogen bond acceptor solvent.

(2) 10% of dodecanoic acid is dissolved in a hydrogen bond acceptor solvent, 12% of beta-cyclodextrin is added, and the mixture is stirred and dissolved to obtain a first mixed solution.

(3) Adding 2% of polyethylene glycol and 2% of carboxymethyl cellulose into the first mixed solution, and uniformly stirring to form a clear supermolecular gel temporary plugging agent.

Wherein example 3 is formulation (3).

Performance testing

The supermolecular gel temporary plugging agent systems of the examples 1-3 and the application examples 1-3, which are applicable to three different stratum temperature conditions, are tested as follows:

1. infrared sign

The solutions before and after gel formation of examples 1 to 3 and application examples 1 to 3 were subjected to KBr tabletting, and the functional groups of the supramolecular gel temporary plugging agent (hereinafter, may also be referred to as a supramolecular gel temporary plugging agent system) were analyzed by a WQF-520 infrared spectrometer; the inclusion between the host and guest before and after formation of the supramolecular gel is known.

Fig. 2 (a) shows an infrared spectrum of the supramolecular gel temporary plugging agent of example 1 of the present invention, fig. 2 (b) shows an infrared spectrum of the supramolecular gel temporary plugging agent of example 2 of the present invention, and fig. 2 (c) shows an infrared spectrum of the supramolecular gel temporary plugging agent of example 3 of the present invention. The experimental results of the formula (1) are shown in fig. 2 (a), the experimental results of the formula (2) are shown in fig. 2 (b), and the experimental results of the formula (3) are shown in fig. 2 (c). By analyzing the infrared spectra of FIG. 2 (a), FIG. 2 (b) and FIG. 2 (c), 3000-3750 cm ^-1 The existence of a broad peak is derived from the stretching vibration of intramolecular and intermolecular hydrogen bonds of beta-cyclodextrin in a system, and 1090cm ^-1 The stretching vibration peak of the primary hydroxyl is shown. 2930cm ^-1 The peak at the site is-CH ₂ -CH antisymmetric stretching vibration peak 2870cm ^-1 at-CH ₃ CH symmetrical telescopic vibration peak of 1660cm ^-1 The stretching vibration peak of carbonyl in amide. The free amide groups generally have a stretching vibration peak of 1700 to 1680cm ^-1 Here 1660cm ^-1 The elastic vibration peak of the amide after being associated means that the atoms or the atomic groups in the center of the amide form complexes or complexes, which is consistent with the process of forming the supermolecular gel temporary plugging agent, and the main object forms a pipeline-shaped stacking structure through inclusion in the system and further wraps and fixes solvent molecules by virtue of interfacial tension and capillary force.

As shown in fig. 2 (a), 2 (b) and 2 (c), the trend of the infrared spectrograms of the supermolecular gel temporary plugging agent system before and after gel formation is basically consistent, no obvious peak shift or disappearance exists before and after gel formation and gel breaking, and the analysis is that the main guest inclusion effect of the beta-cyclodextrin is only intermolecular interaction, and the change behavior of covalent bonds does not exist in the process of heating and gel formation.

2. Scanning electron microscope

Fig. 3 (a) shows a scanning electron microscope image of a supermolecular gel temporary plugging agent xerogel of example 1 of the present invention, fig. 3 (b) shows a scanning electron microscope image of a supermolecular gel temporary plugging agent xerogel of example 2 of the present invention, and fig. 3 (c) shows a scanning electron microscope image of a supermolecular gel temporary plugging agent xerogel of example 3 of the present invention. Formula (1) is shown in fig. 3 (a), formula (2) is shown in fig. 3 (b), and formula (3) is shown in fig. 3 (c). And (3) performing metal spraying treatment on the xerogel sample of the supermolecular gel temporary plugging agent, and observing the microstructure of the xerogel sample by using an electron scanning microscope.

Wherein, the preparation of the supermolecule gel temporary plugging agent xerogel comprises the following steps: and (3) heating the supermolecule gel temporary plugging agent in the formula (1) to 80 ℃, then drying the gel state of the supermolecule gel temporary plugging agent by adopting a vacuum drying oven, setting the temperature to 90 ℃ and the drying time to 24 hours, and taking out the dried temporary plugging agent sample to obtain a xerogel sample of the supermolecule gel temporary plugging agent corresponding to the example 1. And (3) heating the supermolecule gel temporary plugging agent in the formula (2) to 100 ℃, then drying the gel state of the supermolecule gel temporary plugging agent by adopting a vacuum drying oven, setting the temperature to 110 ℃ and the drying time to 24 hours, and taking out the dried temporary plugging agent sample to obtain a xerogel sample of the supermolecule gel temporary plugging agent corresponding to the example 2. And (3) heating the supermolecular gel temporary plugging agent in the formula (3) to 120 ℃, then drying the gel state of the supermolecular gel temporary plugging agent by adopting a vacuum drying oven, setting the temperature to 130 ℃ and the drying time to be 24 hours, and taking out the dried temporary plugging agent sample to obtain a xerogel sample of the supermolecular gel temporary plugging agent corresponding to the example 3.

As shown in fig. 3 (a), 3 (b) and 3 (c), the gel in the Scanning Electron Microscope (SEM) is composed of fibrous structures, the fibrous structures are broken and scattered together, and the fine fibrous structures are mostly peeled off from the fibers and fall near the fibers. The longest gel fiber structure can reach about 40 mu m, and the width is about 1-8 mu m. The xerogel sample is formed into a more compact structure by piling up the slender fibers, so that the supermolecular gel temporary plugging agent has higher strength.

3. X-ray diffraction

FIG. 4 shows the X-ray diffraction of the supramolecular gel temporary blocking agent xerogels of examples 1-3 of the present invention. X-ray diffraction (XRD) is carried out on the xerogel sample of the supermolecular gel temporary plugging agent, so that the morphological information and the structure among the gels can be obtained.

The supramolecular gel temporary plugging agent xerogel of examples 1-3 shown in fig. 4 is the same as the supramolecular gel temporary plugging agent xerogel shown in fig. 3. The gel forming process is a temperature control process, and can not carry out X-ray diffraction test under the high temperature gel state, so that the solvent is removed by utilizing a vacuum drying oven at the gel forming temperature to obtain a xerogel sample for testing, and the structure of the gel under the high temperature can be reserved to the greatest extent under the normal temperature state.

As shown in fig. 4, the molecular arrangement of the beta-cyclodextrin is mainly divided into a cage type and a pipeline type, the characteristic peaks of the cage type arrangement are at 2θ=9.51°,12.81 ° and 18.21 °, while the xerogel sample has more obvious diffraction peaks at 2θ=9.44 °, 12.80 ° and 18.36 °, which are more consistent with the diffraction peaks of the pure beta-cyclodextrin, so that the existence of the cage type arrangement similar to the beta-cyclodextrin in the xerogel sample is proved. The supermolecular gel temporary plugging agent taking dodecanoic acid as a guest has different modes relative to beta-cyclodextrin, and main diffraction peaks of the supermolecular gel temporary plugging agent are located at 11.79 degrees and 20.02 degrees, which shows that a head-to-head channel structure is formed, and the peak position deviation is caused by the inclusion effect of a host on the guest molecule to influence the size of a molecular group.

4. Rheology profile

Rheological property test of supermolecular gel temporary plugging agent is carried out by using Hakk MARS III (Semer Feishier technology Co., ltd.) with temperature set from room temperature to 125 deg.C and shear rate of 100s ^-1 . Fig. 5 (a) shows a supermolecular gel temporary plugging agent gelling temperature profile of example 1 of the present invention, fig. 5 (b) shows a supermolecular gel temporary plugging agent gelling temperature profile of example 2 of the present invention, and fig. 5 (c) shows a supermolecular gel temporary plugging agent gelling temperature profile of example 3 of the present invention. Formula (1) is shown in fig. 5 (a), formula (2) is shown in fig. 5 (b), and formula (3) is shown in fig. 5 (c).

As shown in fig. 5 (a), 5 (b) and 5 (c), when the temperature of the supramolecular gel temporary plugging agent is low at the beginning, the viscosity fluctuation is kept at about 60mpa·s, and as the supramolecular gel temporary plugging agent is heated, the beta-cyclodextrin in the solution starts to slowly form inclusion compounds, and the viscosity also increases. When the temperature is increased to 80-92 ℃, the viscosity of the formula (2) (shown in fig. 5 b) is increased from 130 mPas to 1405 mPas, at the moment, the interior of the supermolecule gel temporary plugging agent is subjected to phase transition to form gel, the sample starts to break gel after the temperature is continuously increased, and the viscosity starts to slowly decrease. Formulation (1) (FIG. 5 a) was able to gel at 60-84℃and reached a maximum gel strength of 1205 mPa.s. In the formulation (3) (FIG. 5 c), the viscosity was kept around 60 mPa.s as the temperature was increased, the temperature in the system of the temporary plugging agent for supermolecular gel was gradually increased, inclusion compounds in the solution were increased, the thermal movement of the molecules was accelerated, and the viscosity was rapidly increased. When the temperature is increased to 100 ℃, gel is formed in the supermolecule gel temporary plugging agent, the viscosity is rapidly increased, the viscosity is suddenly increased from 114 mPa.s to 1329 mPa.s, the supermolecule gel temporary plugging agent breaks gel after the temperature is continuously increased, the viscosity starts to gradually decrease, and the shear thinning characteristic is shown. The supermolecular gel temporary plugging agent can quickly respond to gel at the gelation temperature after the temperature is raised, so that in the fracturing process, the supermolecular gel can quickly plug cracks after the temperature is raised, and even if the viscosity is reduced after gel breaking, effective plugging can be realized within a certain temperature range.

5. Compatibility of medicines

Fig. 6 shows experimental diagrams of the compatibility of examples 1 to 3 of the present invention. And (3) preparing the supermolecular gel temporary plugging agent, and taking pure water, simulated formation water, slick water fracturing fluid and additive-containing fracturing fluid which have the same volume as the supermolecular gel temporary plugging agent after the supermolecular gel temporary plugging agent is stirred uniformly. Pure water, simulated formation water, slickwater fracturing fluid and additive-containing fracturing fluid are respectively added into the supermolecule gel temporary plugging agent. After mixing the two, the mixture was left to stand for 12 hours.

Wherein the additive-containing fracturing fluid comprises one of a bactericide, a drag reducer and a clay stabilizer.

As shown in FIG. 6, after the mixture is respectively mixed with pure water, simulated formation water, slickwater fracturing fluid and additive-containing fracturing fluid and is static for 12 hours, no obvious precipitation is found, and the supermolecular gel system has better compatibility.

6. Quantity of broken gum residue

Supermolecule gel temporary plugging agents are prepared according to examples 1-3, heated to form gel after stirring is completed, and continuously heated to break gel. And (3) carrying out suction filtration on the filter paper by using a vacuum suction filter, recording the weight of the filter paper before suction filtration until no liquid drops exist, placing the filter paper in a constant-temperature drying oven for drying, weighing the weight of the filter paper after drying, and taking the weight of the filter paper before and after drying as the broken gel residue. The experimental results are shown in table 1.

TABLE 1 gel breaking residue amount of three systems

As shown in Table 1, the three supermolecular gel temporary plugging agents have small broken gel residue amount and no obvious gel substance, and most of the three supermolecular gel temporary plugging agents adsorb residual beta-cyclodextrin after filtering filter paper. The method proves that the gel breaking process of the supermolecular gel does not need to add a gel breaker for breaking gel, the blockage can be removed after the gel breaking is cooled to room temperature, and meanwhile, the residue amount of the temporary plugging agent for the breaking gel fracturing of the supermolecular gel after the gel breaking is less.

7. Fluid loss

Fig. 7 (a) shows the fluid loss curve of example 1 of the present invention, fig. 7 (b) shows the fluid loss curve of example 2 of the present invention, and fig. 7 (c) shows the fluid loss curve of example 3 of the present invention. The experimental results of the formula (1), the formula (2) and the formula (3) are shown in figure 7. Formula (1) is shown in fig. 7 (a), formula (2) is shown in fig. 7 (b), and formula (3) is shown in fig. 7 (c). Preparing 200mL of supermolecular gel temporary plugging agents of the formula (1), the formula (2) and the formula (3), paving filter paper with the diameter of 63.5mm and the aperture of 30-50 mu m in a fluid loss cylinder, and pouring the prepared supermolecular gel temporary plugging agents into the fluid loss cylinder. Setting the heating temperature of the filtration apparatus at 90 ℃, 110 ℃ and 130 ℃ respectively, and aging for 40min after the temperature rises to a set value. After aging is finished, maintaining a pressure difference of 3.5MPa, opening a valve of a filtration instrument every 3min, and recording the filtrate quantity of the system solution.

After aging is finished, the filtration loss of the supermolecular gel temporary plugging agent system is larger in the initial stage of the test, and analysis is performed because the thickness of the wall of the filtration loss cylinder is too large, the heat conduction of an instrument is slow, and the supermolecular gel temporary plugging agent system is still in a solution state without gel formation. With continuous heating, gel slowly appears in the fluid loss cylinder, the fluid loss of the supermolecular gel temporary plugging agent is reduced, and when the solution in the cylinder is completely converted into gel, the fluid loss of the supermolecular gel temporary plugging agent is reduced to zero, and no liquid can be filtered out in a longer time, so that the fluid loss performance is better.

8. Occlusion properties

Fig. 8 shows a diagram of a test rig for the test of the blocking strength according to the invention. As shown in fig. 8, the devices are all connected through pipelines, the core holder 7 is used for loading the core with etched cracks, confining pressure is applied to fix the core, the supermolecular gel system loaded in the intermediate container 5 is injected through the ISCO pump 3 through the first six-way valve 4 and is glued in a high-temperature environment, water is pumped into the core holder 7 through the ISCO pump 3 through the second six-way valve 6 at a certain flow rate, and in the whole process, the water can be transmitted to the pressure data collection system 1 through the pressure sensor 2 to clearly determine the pressure change in the flowing process, so that the plugging condition of the supermolecular gel system is clearly determined.

And carrying out constant flow displacement experiments on the artificial joint rock core to determine the plugging strength after the artificial joint rock core is glued. The length and diameter of the artificial joint core were measured and recorded. The core is placed in a core holder, simulated formation water is displaced at a constant flow rate of 5mL/min, and a displacement pressure value is recorded. And (3) displacing the supermolecule gel temporary plugging agent at the flow of 5mL/min, closing a valve at the outflow end after 30min, heating to the gel temperature, and holding the pressure for 1h. And (3) displacing the simulated formation water at a constant flow of 5mL/min, heating to a gel breaking temperature after 30min, and recording a displacement pressure change value. And closing the constant flow pump, discharging residual liquid in the liquid storage tank, and taking out the rock core.

Fig. 9 (a) shows a plot of the test pressure of the seal strength versus the injection time for example 1 of the present invention, fig. 9 (b) shows a plot of the test pressure of the seal strength versus the injection time for example 2 of the present invention, and fig. 9 (c) shows a plot of the test pressure of the seal strength versus the injection time for example 3 of the present invention. Formula (1) is shown in fig. 9 (a), formula (2) is shown in fig. 9 (b), and formula (3) is shown in fig. 9 (c). As shown in fig. 9 (a), 9 (b) and 9 (c), the plugging property of the supramolecular gel temporary plugging agent was tested by using a constant flow pump, wherein the displacement flow rate was set to 5mL/min. After the supermolecule gel system which is in a liquid state at normal temperature is displaced to the pressure stability through the core which is not completely broken at the flow rate of 5mL/min, the supermolecule gel temporary plugging agent taking the dodecanoic acid as an object is injected, self-diverting fracturing fluid in the core gradually forms gel under the gel forming strip parts shown in the figure 9 (a), the figure 9 (b) and the figure 9 (c), and the injection pressure of the constant flow pump continuously rises. After about 45 minutes, the injection pressure tended to stabilize at about 8.42MPa. The pressure is kept for 6 hours without pressure break-through. After the temperature of the oven is increased to the gel breaking temperature, partial gel breaking phenomenon occurs in a gel forming system in the shale core, and the pressure is continuously reduced. In the dynamic liquid injection process, the calculation result of the blocking strength of the system is shown in table 2.

TABLE 2 blocking Strength test results (dynamic)

As shown in Table 2, the maximum plugging pressure of the supermolecular gel system on the broken rock core is 8.42MPa, and the impact pressure gradient reaches 168.06 MPa.m ^-1 The plugging capability is better.

Comparative examples A1 to E6

Establishing 5 factors influencing the construction of the temporary plugging agent of the supermolecular gel, namely the solvent type, the object type, the stirring time, the object concentration and the host concentration; wherein, the stirring time refers to the stirring time after all components are added into the temporary plugging agent system; the addition ranges of the 5 factors are respectively determined as solvent types DMSO (dimethyl sulfoxide), DMEA (N, N-dimethylethanolamine), DMI (1, 3-dimethyl-2-imidazolidinone), DMF (N, N-dimethylformamide), DMAc (N, N-dimethylacetamide), guest types (long-chain even-carbon saturated fatty acid C ₁₀ ～C ₁₆ ) The screening experiments were performed for the stirring time (3 h, 6h, 9h, 12h, 36h, 54 h), and the host concentration (9.5%, 13%, 16.5%, 20%, 23.5%, 27%) and the guest concentration (2.4%, 4.8%, 9.6%, 14.4%, 19.2%, 24%).

Comparative examples A1 to A12

Comparative examples A1 to A12 are screening of solvent series. Samples with a host concentration of 10% and a guest concentration of 5% were placed in test tubes using water and DMSO, DMEA, DMI, DMAc, DMF, respectively. The host molecule is beta-cyclodextrin, and the guest molecule is dodecanoic acid. The test tube was fixed with a test tube clamp, the temperature rise treatment was performed using an oil bath, the recorded phenomenon was observed, the sample was prepared, and the same host-guest concentration was prepared using a solvent to which 0.5% lithium chloride was added, and the above steps were repeated to perform the experiment. The results of the experiments performed by heating the bodies constructed with different solvents are shown in Table 3.

TABLE 3 different solvents build supermolecular gel to gel state

Table 3 shows experimental results of gel formation of supramolecular gel by different solvents. The experimental results show that the supermolecular gel system without lithium chloride does not form gel after being heated, but the supermolecular gel system with lithium chloride does not react at normal temperature and can form a system with DMF and DMAc as solvents after being heated. Further analysis of the solvent structure shows that the cyclic structure of the solvent affects the formation of hydrogen bonds between beta-cyclodextrin molecules, which makes it difficult to form a gel, while Li in lithium chloride ⁺ The carbonyl groups of the molecules are influenced, so that the solvent plays a role in the construction of a gel system, and DMF and DMAc are good hydrogen bond acceptor solvents in the presence of lithium chloride and can participate in and promote the formation of supramolecular gel. But is sterically hindered more than DMF by the molecular structure of DMAc when reacted with beta-cyclodextrin compared to DMF solvent, resulting in a gel formed with DMAc solvent having less strength than a gel formed with DMF. The strength of DMF system is most suitable in all systems, so DMF and lithium chloride are selected as solvents for constructing the system.

Comparative examples B1 to B12

Comparative examples B1-B12 are the effects of guest molecular species on supramolecular gel temporary plugging systems. The method comprises the steps of fixing a host molecule beta-cyclodextrin with the concentration of 10%, changing the types of guest molecules under the condition that a solvent is DMF and 0.5% lithium chloride, measuring the gel forming temperature range of a system under different guest molecules, observing the experimental phenomenon of mild temperature rise of a supermolecule gel temporary plugging agent system, simultaneously observing the influence of a gel strength regulator on the gel forming temperature of the supermolecule gel temporary plugging agent system through testing, and recording the gel forming temperature range. The experimental results are shown in table 4 and fig. 10.

TABLE 4 determination of gel forming temperature of supramolecular gel constructed by different gel factors

FIG. 10 is a graph showing the effect of the guest molecule species of comparative examples B1 to B12 on the gelation temperature of the supramolecular gel temporary plugging agent according to the present invention. As shown in Table 4 and FIG. 10, the hydrophobic chain length is at C ₁₀ ～C ₁₆ When saturated fatty acid in the interval is used as a guest molecule, the system has the gelling capability. Wherein the hydrophobic chain length is C ₁₀ ～C ₁₄ In the range, the gel forming temperature of the system tends to be reduced along with the increase of the chain length, wherein when the guest molecule is dodecanoic acid, the system has a larger gel forming temperature range and better gel forming strength.

Comparative examples C1 to C6

Comparative examples C1-C6 effect of mixing duration on supermolecular gel temporary plugging agent system. Samples with a bulk concentration of 10% and a guest concentration of 5% were prepared in round bottom flasks using 50mL DMF and 0.5% lithium chloride, respectively. The host molecule is beta-cyclodextrin, and the guest molecule is dodecanoic acid. And placing the prepared solution on a stirrer for stirring, wherein the stirring time is respectively 3h, 6h, 9h, 12h, 36h and 54h, and recording the change of the solution before and after stirring. After stirring, all the solutions were heated to form a gel, during which the temperature at which the solutions produced gel and broken gel was recorded. When the liquid starts to be turbid, the temperature is recorded as an initial gel forming temperature, when the liquid loses fluidity, the recorded temperature is a gelation temperature, the temperature at which gel starts to break gel after heating can slide from the wall surface is recorded as a gel breaking temperature, and the range from the gel forming temperature to the gel breaking temperature is the gel forming temperature range of the system. The experimental results are shown in fig. 11 and table 5.

Wherein the liquid loses fluidity in an invertible state.

TABLE 5 supermolecule gel formation temperature test at different agitation time periods

FIG. 11 is a graph showing the effect of the mixing stirring period of comparative examples C1 to C6 on the gelation temperature of the supramolecular gel temporary plugging agent of the present invention. As shown in fig. 11 and table 5, when the stirring period is 6 hours or less, the gelling temperature of the supramolecular gel temporary plugging agent system increases as the stirring period increases; when the stirring time exceeds 6 hours, the gel forming temperature of the supermolecular gel temporary plugging agent system tends to decrease along with the increase of the stirring time, but the gel forming temperature range also tends to be fixed. Therefore, insufficient stirring time of the supermolecular gel system can cause insufficient inclusion between host and guest molecules and unstable gel forming temperature and the like. In order to uniformly mix the systems, the main body and the guest body are fully included, and the continuous stirring is required to be carried out for more than 9 hours during the preparation.

Comparative examples D1 to D6

Comparative examples D1 to D6 are the effects of guest molecule concentration on the gelation temperature of the supramolecular gel temporary plugging agent. The concentration of the immobilized host molecule beta-cyclodextrin is 10%, the guest molecule is dodecanoic acid, the concentration of the guest molecule dodecanoic acid is changed under the condition that the solvent is DMF and 0.5% lithium chloride, the gel forming temperature range of the system under different guest molecule concentrations is measured, the experimental phenomenon of the system at the temperature and the temperature rise is observed, the gel forming temperature range is recorded, and the like. The experimental results are shown in table 6 and fig. 12.

TABLE 6 gel formation temperature test of different concentrations of guest molecules involved in the construction of supramolecular gel systems

FIG. 12 is a graph showing the effect of the concentration of guest molecules on the gelation temperature of the supramolecular gel temporary plugging agent, wherein the concentration of the gel factor is less than or equal to 2.4% when the concentration of the immobilized host molecule beta-cyclodextrin is 10% as shown in FIG. 12 and Table 6, the supramolecular gel temporary plugging agent system has the capability of thermally gelling, but the gelling is not complete.

As shown in table 6 and fig. 12, the initial gel forming temperature of the supramolecular gel system decreases with increasing guest molecule concentration. When the concentration of the guest molecules is increased, the temperature is increased, the thermal motion condition of the molecules in the solvent is increased, and meanwhile, the number of the guest molecules is increased, so that more guest molecules can be included by cyclodextrin. The inclusion rate increases, the inclusion compound also increases with the increase of concentration, the number of inclusion compounds in unit volume increases, and the inclusion compound is easier to form a stacked structure under lower energy, so the initial gel forming temperature is reduced.

The apparent strength of the supermolecular gel formed is reduced instead as the concentration of the guest continuously increases, and the analysis is that the concentration of the host system is unchanged, so that the guest molecules which can be included are limited, and as the number of the guest molecules increases, excessive guest molecules cannot be included by beta-cyclodextrin, so that the guest molecules are free and occupy the gaps of the inclusion compound, the regular structure formed by self-assembly of the inclusion compound is destroyed, and the apparent strength is reduced. So that the addition amount of the guest molecule can have higher gel forming strength within the range of 5-15 percent.

Comparative examples E1 to E6

Comparative examples E1 to E6 are the effects of the concentration of the host molecule on the gelation temperature of the supramolecular gel temporary plugging agent. Fixing 5% of guest molecule dodecanoic acid concentration, 50mL of DMF and 0.5% of lithium chloride as solvent, changing the concentration of host molecule beta-cyclodextrin, measuring the gel forming temperature range of the system under different host molecule concentrations, observing the experimental phenomenon of the system with mild temperature rise, and recording the gel forming temperature range. The experimental results are shown in table 7 and fig. 13.

TABLE 7 gel formation temperature test of the participation of host molecules of different concentrations in the construction of supramolecular gel systems

FIG. 13 is a graph showing the effect of the concentration of host molecules of comparative examples E1 to E6 on the initial gel forming temperature of the supramolecular gel temporary plugging agent of the present invention. From the graphs of the results of the effect of the concentration of the host molecule on the initial gelling temperature of the supramolecular gel temporary plugging agent shown in fig. 13 and table 7, it can be seen from fig. 13 that the system does not have the capability of thermally gelling when the ratio of β -cyclodextrin to the guest molecule is 1:10, i.e., when the concentration of cyclodextrin is less than or equal to 6% in the case where the guest molecule is 5%. As the concentration of host molecules increases, the initial gel forming temperature of the system gradually decreases. When the concentration of cyclodextrin reaches 27%, the solution is a milky white solution at normal temperature, part of beta-cyclodextrin is not completely dissolved, the solution reaches a saturated state, the solubility of cyclodextrin becomes large after heating, and the solution becomes clear and transparent.

As shown in fig. 13 and table 7, the concentration of the host and the gel forming temperature change in a linear relationship, the gel forming temperature decreases with increasing concentration of the host, and the increase of the host β -cyclodextrin can adjust the gel forming temperature and the gel forming strength in a larger range than the guest molecule.

Although the present invention has been described above by way of the combination of the exemplary embodiments, it should be apparent to those skilled in the art that various modifications and changes can be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined in the appended claims.

Claims

1. A supramolecular gel temporary plugging agent, characterized in that it comprises: beta-cyclodextrin, even-carbon saturated fatty acid, N-dimethylformamide, lithium chloride, polyethylene glycol and methyl cellulose, wherein the carbon number of the even-carbon saturated fatty acid is 10-16, the molecular weight of the polyethylene glycol is 400-1000, and the molecular weight of the carboxymethyl cellulose is 400-1000.

2. The supramolecular gel temporary plugging agent according to claim 1, which is suitable for stratum at 60-130 ℃, and comprises the following components of 12-20% of beta-cyclodextrin, 5-10% of even-numbered saturated fatty acid, 67-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-10% of polyethylene glycol and 0.5-2% of carboxymethyl cellulose by mass percent.

3. The supramolecular gel temporary plugging agent according to claim 2, which is suitable for a stratum at 60-90 ℃, and comprises the following components, by mass, 15-18% of beta-cyclodextrin, 5-7% of even-numbered saturated fatty acid, 68-69% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 8-10% of polyethylene glycol and 0.3-0.7% of carboxymethyl cellulose.

4. The supramolecular gel temporary plugging agent according to claim 2, which is suitable for stratum at 90-110 ℃, and comprises the following components of 18-20% of beta-cyclodextrin, 7-9% of even-numbered saturated fatty acid, 67-68% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 4-8% of polyethylene glycol and 0.7-1.5% of carboxymethyl cellulose by mass percent.

5. The supramolecular gel temporary plugging agent according to claim 2, which is suitable for stratum at 110-130 ℃, and comprises the following components of 12-15% of beta-cyclodextrin, 9-10% of even-numbered saturated fatty acid, 69-73.5% of N, N-dimethylformamide, 0.4-0.6% of lithium chloride, 2-4% of polyethylene glycol and 1.5-2% of carboxymethyl cellulose by mass percent.

6. The supramolecular gel temporary plugging agent according to any one of claims 1-5, wherein the supramolecular gel temporary plugging agent undergoes a "liquid-gel-liquid" transition with increasing temperature, being liquid in a first temperature interval, being gel in a second temperature interval, being liquid in a third temperature interval, the first temperature interval being lower than the second temperature interval, the second temperature interval being lower than the third temperature interval.

7. A method for preparing a supramolecular gel temporary plugging agent according to any one of claims 1-6, comprising the steps of:

s1, dissolving lithium chloride in N, N-dimethylformamide, and uniformly mixing to form a hydrogen bond acceptor solvent;

s2, dissolving even-numbered saturated fatty acid in a hydrogen bond acceptor solvent, adding beta-cyclodextrin, stirring and dissolving to obtain a first mixed solution; and

s3, adding polyethylene glycol and carboxymethyl cellulose into the first mixed solution, and uniformly stirring to form a clear supermolecular gel temporary plugging agent.

8. The method for preparing a supramolecular gel temporary plugging agent according to claim 7, wherein the step S3 comprises:

s31, sequentially adding polyethylene glycol and carboxymethyl cellulose into the first mixed solution, and uniformly stirring;

S32, stirring time is more than 9h, and stirring speed is 290-310 r/min.

9. The method for preparing a supramolecular gel temporary plugging agent according to claim 7, wherein the step S2 comprises:

even saturated fatty acid is dissolved in hydrogen bond acceptor solvent, and beta-cyclodextrin is added into the solvent at the speed of 0.7-1.2 g/min, stirred and dissolved.

10. The method for preparing a supramolecular gel temporary plugging agent according to claim 7, wherein at least one of the steps S1 to S3 is performed at normal temperature.