CN110655912A

CN110655912A - Boron crosslinking agent composition, boron crosslinking agent and preparation method thereof, and guanidine gum fracturing fluid composition containing boron crosslinking agent composition

Info

Publication number: CN110655912A
Application number: CN201810714479.3A
Authority: CN
Inventors: 董景锋; 潘竟军; 汪志臣; 怡宝安; 翟怀建; 李晓艳
Original assignee: China Petroleum and Natural Gas Co Ltd
Current assignee: China Petroleum and Natural Gas Co Ltd
Priority date: 2018-06-29
Filing date: 2018-06-29
Publication date: 2020-01-07

Abstract

The invention provides a boron crosslinking agent composition, a boron crosslinking agent, a preparation method of the boron crosslinking agent and a guanidine gum fracturing fluid composition containing the boron crosslinking agent. The boron crosslinker composition comprises, in parts by weight: 10-15 parts of a boron compound; 35-50 parts of a liquid organic solvent; 5-10 parts of tetraethyl pentamine; 2-5 parts of solid polyol; 10-15 parts of alkali by 20-50 wt% of alkali solution; and glyoxal, 5-38 parts by weight of a 40 wt% aqueous glyoxal solution. By developing the efficient boron crosslinking agent, the use concentration of the guanidine gum in the guanidine gum fracturing fluid is effectively reduced, and the use concentration of the guanidine gum is reduced under the condition of ensuring the normal performance of the fracturing fluid, so that the residue content of the fracturing fluid is reduced, the damage to a reservoir is reduced, and the aims of reducing cost and improving efficiency are fulfilled.

Description

Boron crosslinking agent composition, boron crosslinking agent and preparation method thereof, and guanidine gum fracturing fluid composition containing boron crosslinking agent composition

Technical Field

The invention relates to the technical field of oil exploitation, and particularly relates to a boron crosslinking agent composition, a boron crosslinking agent, a preparation method of the boron crosslinking agent and a guanidine gum fracturing fluid composition containing the boron crosslinking agent.

Background

Hydraulic fracturing is one of the important production increasing measures for increasing the production of oil and gas wells, increasing the injection of water injection wells and improving the productivity and recovery ratio of the oil and gas wells. The hydraulic fracturing is carried out by a high-pressure pump truck, high-viscosity fracturing fluid is used for injecting the fracturing fluid exceeding the stratum absorption capacity into a well, high pressure is formed near the bottom of the well, the pressure exceeds the ground stress and the tensile strength of a rock to form a fracture, the fracturing fluid with propping agent is continuously injected into the fracture, the fracture extends and is filled with the propping agent, after the pump is stopped, the fracturing fluid breaks the gel and returns to the original shape, the propping agent is remained in the fracture, and a sufficiently long high-conductivity sand-filled fracture with a certain width and height is formed in the stratum, so that the permeability of an oil-gas layer is improved, and the yield of the oil-gas well is increased.

The fracturing fluid is used as a working fluid in the process of hydraulic fracturing modification of an oil-gas layer, and plays the roles of transferring pressure, forming cracks, carrying a propping agent, breaking gel and hydrating after fracturing is finished to reduce viscosity and ensuring that most of the fracturing fluid is returned to the ground to purify the cracks. The quality of the fracturing fluid is an important factor related to success or failure of fracturing construction and influencing the yield increasing effect after fracturing. The most widely used fracturing fluid in reservoir transformation is a jelly system formed by using guanidine gum as a thickening agent and boron, zirconium and the like as cross-linking agents. The boron crosslinked guanidine gum gel has high viscosity, good shear recovery performance and excellent proppant wrapping and conveying performance. However, the guanidine gum fracturing fluid has high residue content, and is easy to damage the matrix permeability and the propped fracture to influence the reservoir transformation effect.

The water-insoluble matters of the guanidine gum thickener and the like are main sources of the guanidine gum fracturing fluid residues, and the residue content of the guanidine gum fracturing fluid is mainly reduced by the following two ways at present: (1) modifying guar gum molecules to improve the purity of the guar gum, thereby reducing the content of water-insoluble substances; (2) the formula of the fracturing fluid is optimized, and the concentration of a thickening agent guanidine gum is reduced, so that the content of residues is reduced. Research shows that the effective reduction of the concentration of the thickening agent guanidine gum can be realized by developing a high-efficiency boron crosslinking agent, the improvement of the crosslinking efficiency is mainly realized by complexing borate and an organic ligand at present, but the reduction of the concentration of the guanidine gum is limited.

Chinese patent CN 102775979A introduces an efficient cross-linking agent for reducing the use concentration of guar gum in fracturing fluid and a preparation method thereof, and reduces the requirement of cross-linking reaction on the concentration of a thickening agent in the environment by enlarging the action distance of cross-linking ion space. The cross-linking agent comprises borate, sodium hydroxide, sodium carbonate and a phenylboron cyclic compound. The cross-linking agent can reduce the use concentration of the guanidine gum thickener by 25 percent compared with the conventional system on the premise of ensuring the same use performance. According to the cross-linking agent preparation technology, the boron benzene ring-shaped compound is introduced, the cross-linking ion space action distance is increased, and the concentration of the thickening agent is reduced, but the boron benzene ring-shaped compound is expensive and cannot be effectively popularized and applied industrially, and the use concentration of the thickening agent guar gum is not determined, so that the application prospect is poor.

Therefore, there is a need to develop a high-efficiency boron crosslinking agent to effectively reduce the concentration of guar gum, thereby reducing reservoir damage, improving reservoir modification effect and increasing the yield of oil and gas wells.

Disclosure of Invention

The invention mainly aims to provide a boron crosslinking agent composition, a boron crosslinking agent, a preparation method of the boron crosslinking agent and a guanidine gum fracturing fluid composition containing the boron crosslinking agent, so as to solve the problem that the guanidine gum in the guanidine gum fracturing fluid in the prior art is high in use concentration.

To achieve the above object, according to one aspect of the present invention, there is provided a boron crosslinker composition comprising, in parts by weight: 10-15 parts of a boron compound; 35-50 parts of a liquid organic solvent; 5-10 parts of tetraethyl pentamine; 2-5 parts of solid polyol; 10-15 parts of alkali by 20-50 wt% of alkali solution; and glyoxal, 5-38 parts by weight of a 40 wt% aqueous glyoxal solution.

Further, the boron compound is any one or two of boric acid and borax.

Further, the liquid organic solvent is an alcohol solvent, preferably the alcohol solvent is any one or more of ethylene glycol, butanol, pentanol and hexanol.

Further, the solid polyol is any one or more of sorbitol, pentaerythritol, dipentaerythritol and N-methylglucamine.

The alkali is provided in the form of an alkali solution, preferably an alkali solution having a concentration of 20 to 50 wt%, more preferably either one or both of an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution having a concentration of 20 to 50 wt%.

According to another aspect of the present invention, there is provided a method for producing a boron crosslinking agent, which is produced using any one of the above-described boron crosslinking agent compositions as a raw material.

Further, the preparation method comprises the following steps: step S1: mixing an organic solvent with a boron compound to obtain a first mixture; step S2: mixing tetraethyl pentamine with the first mixture to obtain a second mixture; step S3: mixing a polyol with the second mixture to obtain a third mixture; and step S4: and mixing alkali, glyoxal and the third mixture to obtain the boron crosslinking agent.

Further, the step S1 includes: mixing an organic solvent with a boron compound to obtain a first premix; and heating the first premix to a first temperature under magnetic stirring, and carrying out magnetic stirring for 10-20 min at the first temperature to obtain a first mixture, wherein the first temperature is 100-150 ℃.

Further, the step S2 includes: cooling the first mixture to a second temperature, wherein the second temperature is 25-35 ℃; adding tetraethylpentamine to the first mixture at a second temperature to obtain a second premix; and under the magnetic stirring, heating the second premix to a third temperature, and carrying out magnetic stirring for 3-5 h at the third temperature to obtain a second mixture, wherein the third temperature is 120-160 ℃.

Further, the step S3 includes: cooling the second mixture to a fourth temperature, wherein the fourth temperature is 25-35 ℃; adding a polyol to the second mixture at a fourth temperature to provide a third premix; and under the magnetic stirring, heating the third premix to a fifth temperature, and carrying out magnetic stirring for 0.5-1 h at the fifth temperature to obtain a third mixture, wherein the fifth temperature is 50-100 ℃.

Further, the step S4 includes: cooling the third mixture to a sixth temperature, wherein the sixth temperature is 25-35 ℃; adding a base and glyoxal to the third mixture at a sixth temperature under magnetic stirring to obtain the boron crosslinker.

According to still another aspect of the present invention, there is provided a boron crosslinking agent prepared by the preparation method of any one of the above.

According to another aspect of the invention, a guanidine gum fracturing fluid composition is provided, which comprises guanidine gum, water, a crosslinking agent and a pH regulator, wherein the crosslinking agent is the boron crosslinking agent. .

Further, the composition comprises, by weight, 0.12-0.3 part of guar gum, 0.2-0.5 part of a cross-linking agent, 0.005-0.02 part of a pH regulator and 99.18-99.675 parts of water.

Further, the composition optionally comprises an anti-swelling agent, a discharge assistant and a bactericide, and preferably, the composition optionally comprises the following components in parts by weight: 0.5-2 parts of an anti-swelling agent; 0.3-1 part of a cleanup additive; and 0.05-0.1 part of bactericide.

Further, the pH adjuster is an alkaline substance, preferably one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

By applying the technical scheme of the invention, the use concentration of the guanidine gum in the guanidine gum fracturing fluid is effectively reduced by developing the efficient boron crosslinking agent, and the use concentration of the guanidine gum is reduced under the condition of ensuring the normal performance of the fracturing fluid, so that the residue content of the fracturing fluid is reduced, the damage to a reservoir stratum is reduced, and the aims of reducing cost and improving efficiency are fulfilled.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As analyzed by the background art, the fracturing fluid widely used in reservoir reformation at present contains guanidine gum with higher concentration as a thickening agent, and the residue content (the main source of the fracturing fluid is water-insoluble substances of the guanidine gum thickening agent and the like) of the fracturing fluid is higher, so that the matrix permeability and the propped fracture are easily damaged to influence the reservoir reformation effect. In order to reduce the residue content of the fracturing fluid, one method is to modify guar gum molecules to improve the purity of the guar gum so as to reduce the content of water-insoluble substances; another approach is to reduce the thickener guar concentration and thus reduce the residue content. The present inventors have sought to reduce the viscosifier guar concentration and thereby reduce the fracturing fluid residue content by seeking a highly effective crosslinker. In order to achieve the object, the inventors of the present application carried out a large number of experiments and provided a boron crosslinking agent composition, a boron crosslinking agent, a method for producing the same, and a guanidine gum fracturing fluid composition containing the same based on the experiments.

In one embodiment of the present application, there is provided a boron crosslinker composition comprising, in parts by weight: 10-15 parts of a boron compound; 35-50 parts of a liquid organic solvent; 5-10 parts of tetraethylpentamine; 2-5 parts of solid polyol; 10-15 parts of alkali by 20-50 wt% of alkali solution; and 5 to 38 parts of glyoxal calculated by 40 wt% aqueous glyoxal solution.

The boron crosslinking agent formed by the boron crosslinking agent composition with the composition can effectively improve the molecular weight of the boron crosslinking agent, increase boron crosslinking sites and realize effective crosslinking under the condition of low-concentration guanidine gum fracturing fluid; the cross-linked low-concentration guanidine gum fracturing fluid has higher viscosity, good shear recovery performance and excellent proppant wrapping and conveying performance, and can reduce the use concentration of guanidine gum under the condition of ensuring the normal performance of the fracturing fluid, thereby reducing the residue content of the fracturing fluid, lightening the damage of a reservoir and achieving the purposes of reducing cost and improving efficiency.

Borides that may be used in the boron crosslinker compositions herein include both organic borides and inorganic borides. The inorganic boride has advantages such as non-toxicity and low cost compared with the organic boride, and therefore, the boron compound to be preferably used is either one or both of boric acid and borax.

The liquid organic solvent used in the above boron crosslinker composition is not particularly limited as long as the use of the organic solvent does not affect the reaction of the respective substances. In a preferred embodiment of the present application, the liquid organic solvent is an alcoholic solvent, and preferably the alcoholic solvent is any one or more of ethylene glycol, butanol, pentanol, hexanol.

Further, in order to reduce costs, the solid polyol used in the above boron crosslinker composition is any one or more of sorbitol, pentaerythritol, dipentaerythritol, N-methylglucamine. However, it is known to those skilled in the art that the solid polyol is not limited thereto.

As described above, a portion of the base may be used to adjust the pH and thereby increase the degree of hydrolysis of the boron compound, and a portion of the base may have OH^-Can participate in the reaction for preparing the cross-linking agent. For convenience of use, the base used is provided as an alkaline solution. In addition, in order to save cost, the alkali used in the present application is preferably provided in the form of 20 to 50 wt% alkali solution. Since sodium hydroxide and potassium hydroxide are commonly used as inexpensive bases, it is preferable to use either or both of a 20 to 50 wt% aqueous solution of sodium hydroxide and an aqueous solution of potassium hydroxide.

In another embodiment of the present application, a method for preparing a boron crosslinking agent is provided, wherein the boron crosslinking agent is prepared by using any one of the above boron crosslinking agent compositions as a raw material.

The boron crosslinking agent formed by the boron crosslinking agent composition with the composition has higher viscosity, good shear recovery performance and excellent proppant wrapping and conveying performance when being crosslinked with the low-concentration guanidine gum fracturing fluid, and simultaneously reduces the use concentration of guanidine gum under the condition of ensuring the normal performance of the fracturing fluid, thereby reducing the residue content of the fracturing fluid, lightening the damage of a reservoir and achieving the purposes of reducing cost and improving efficiency.

In order to crosslink well the respective components of the boron crosslinking agent composition having the above composition, it is preferable that the above method includes step S1: mixing an organic solvent with a boron compound to obtain a first mixture; step S2: mixing tetraethyl pentamine with the first mixture to obtain a second mixture; step S3: mixing a polyol with the second mixture to obtain a third mixture; and step S4: and mixing alkali, glyoxal and the third mixture to obtain the boron crosslinking agent. The reactants are respectively added into the solvent, so that the former reactant is uniformly mixed in the solvent and then the latter reactant is added, and a uniformly stirred mixture can be obtained and can be subjected to stepwise reaction, so that the reactants are reacted in each step to a more ideal degree.

Further, since the organic solvent contains a small amount of water and the boron compound also contains crystal water, it is preferable that the step S1 includes: mixing an organic solvent with a boron compound to obtain a first premix; and heating the first premix to a first temperature under magnetic stirring, and carrying out magnetic stirring for 10-20 min at the first temperature to obtain a first mixture, wherein the first temperature is 100-150 ℃. The water in the reaction system can be completely removed by using the temperature of 100-150 ℃, and the energy can be saved.

In a preferred embodiment of the present application, the step S2 includes: cooling the first mixture to a second temperature, wherein the second temperature is 25-35 ℃; adding tetraethylpentamine to the first mixture at a second temperature to obtain a second premix; and under the magnetic stirring, heating the second premix to a third temperature, and carrying out magnetic stirring for 3-5 h at the third temperature to obtain a second mixture, wherein the third temperature is 120-160 ℃.

In a preferred embodiment of the present application, the step S3 includes: cooling the second mixture to a fourth temperature, wherein the fourth temperature is 25-35 ℃; adding a polyol to the second mixture at a fourth temperature to provide a third premix; and under the magnetic stirring, heating the third premix to a fifth temperature, and carrying out magnetic stirring for 0.5-1 h at the fifth temperature to obtain a third mixture, wherein the fifth temperature is 50-100 ℃.

In a preferred embodiment of the present application, the step S4 includes: cooling the third mixture to a sixth temperature, wherein the sixth temperature is 25-35 ℃; adding a base and glyoxal to the third mixture at a sixth temperature under magnetic stirring to obtain the boron crosslinker.

Performing the reaction according to the above-described step S2, step S3, and step S4 can allow each reactant to be better brought into contact with a boron compound, thereby better performing the reaction. Preferably, to coordinate glyoxal better, the base is added to the third mixture before glyoxal is added in step S4, above.

In yet another embodiment of the present application, a boron crosslinking agent is provided, which is prepared by the above preparation method. The boron crosslinking agent prepared by the application and the low-concentration guanidine gum have high viscosity, good shear recovery performance, excellent proppant wrapping and conveying performance, and simultaneously, the use concentration of the guanidine gum is reduced under the condition of ensuring the normal performance of the fracturing fluid, so that the residue content of the fracturing fluid is reduced, the damage to a reservoir is reduced, and the purposes of reducing cost and improving efficiency are achieved.

In yet another embodiment of the present application, a guar gum fracturing fluid composition is provided, comprising guar gum, water, a crosslinking agent and a pH adjusting agent, wherein the crosslinking agent is a boron crosslinking agent prepared by using the crosslinking agent composition having any of the above compositions. The presence of water allows the components to dissolve in the water, thereby increasing the chance of contact between the reactants, facilitating the crosslinking reaction, and controlling the crosslinking time by the addition of a pH adjusting agent. The boron crosslinking agent and the low-concentration guanidine gum have high viscosity, good shear recovery performance and excellent proppant wrapping and conveying performance in crosslinking, and meanwhile, under the condition of ensuring normal performance of the fracturing fluid, the use concentration of the guanidine gum in the guanidine gum fracturing fluid composition can be reduced, so that the residue content of the fracturing fluid is reduced, the damage to a reservoir is reduced, and the aims of reducing cost and improving efficiency are fulfilled. In a preferred embodiment of the present application, the composition comprises 0.12 to 0.3 parts of guar gum, 0.2 to 0.5 parts of a cross-linking agent, 0.005 to 0.02 parts of a pH regulator, and 99.18 to 99.675 parts of water. The amount of the conventional guanidine gum in the field is more than 0.4 part, which may cause high residue content of the fracturing fluid and great damage to a reservoir. The dosage of the guanidine gum is obviously reduced, so that the technical problem is solved more stably.

Further, in order to optimize the performance of the composition, the composition optionally comprises an anti-swelling agent, a discharge assistant and a bactericide, and preferably, the composition optionally comprises the following components in parts by weight: 0.5-2 parts of an anti-swelling agent; 0.3-1 part of a cleanup additive; and 0.05-0.1 part of bactericide. The above optional anti-swelling agents, discharge aids and biocides are known in the art, for example, the anti-swelling agent may be one or more of gypsum, potassium carbonate, trichloromethylsilane, silicofluoride, potassium chloride or ammonium chloride, the discharge aid is a non-ionic surfactant, and the biocide is one or more of liquid chlorine, calcium hypochlorite, sodium chlorite, chlorine dioxide, chlorophenol and its derivatives, dithiocyano methane, heterocyclic amine based compounds and formaldehyde.

Further, in order to allow the crosslinking reaction to proceed more rapidly and completely, the pH adjustor is an alkaline substance. In order to reduce the operation cost, it is preferable that the pH adjuster is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

The advantageous effects of the present application will be further described below with reference to examples and comparative examples.

The raw materials used in the following examples include the following components:

boron compound: boric acid and borax which are industrial products;

liquid organic solvent: ethylene glycol and amyl alcohol, both industrial products;

tetraethyl pentamine: chemical purity;

solid polyol: sorbitol, pentaerythritol, N-methylglucamine

Alkali: 20 wt% sodium hydroxide aqueous solution and 50 wt% potassium hydroxide aqueous solution, which are industrial products;

glyoxal: 40 wt% aqueous glyoxal solution, industrial;

guanidine gum: jiayi first-grade guanidine gum.

Example 1:

the crosslinking agent provided by this embodiment includes the following components in parts by weight:

preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 100 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 120 ℃, magnetically stirring at a constant temperature for 3h, cooling to room temperature, adding sorbitol into the reactor, heating to react to 50 ℃, magnetically stirring at a constant temperature for 1h, cooling to room temperature, adding a sodium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent in the embodiment 1.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the cross-linking agent of example 1 is added to the base fracturing fluid and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 59mPa & s, and the use concentration of the guanidine gum is obviously reduced.

Example 2:

preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 150 ℃, magnetically stirring at constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 160 ℃, magnetically stirring at constant temperature for 5h, cooling to room temperature, adding N-methylglucamine into the reactor, simultaneously heating to react to 100 ℃, magnetically stirring at constant temperature for 1h, cooling to room temperature, adding a sodium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent in the embodiment 2.

Preparing the guanidine gum fracturing fluid: slowly adding 0.15 part of guar gum into 99.34 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.01 part of sodium hydroxide, 2.0 parts of ammonium chloride, 1.0 part of cleanup additive and 0.1 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.2 part of the cross-linking agent in the embodiment 2 is added into the base fluid of the fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 80 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 62mPa & s, and the use concentration of the guanidine gum is obviously reduced.

Example 3:

preparation of the crosslinking agent: adding pentanol and boric acid into a reactor, magnetically stirring for 20min, heating to 130 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 160 ℃, magnetically stirring at the constant temperature for 5h, cooling to room temperature, adding N-methylglucamine into the reactor, simultaneously heating to react to 80 ℃, magnetically stirring at the constant temperature for 1h, cooling to room temperature, adding a potassium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent in the embodiment 3.

Preparing the guanidine gum fracturing fluid: slowly adding 0.2 part of guar gum into 99.52 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.015 part of potassium hydroxide, 1.0 part of potassium chloride, 0.5 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the cross-linking agent in the embodiment 3 is added into the base fluid of the fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 100 ℃, and the shearing rate is 170s^-1Shearing for 60min under the condition of normal temperature,the viscosity of the fracturing fluid can be kept at 68 mPas, and the using concentration of guanidine gum is obviously reduced.

Example 4:

preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 140 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 150 ℃, magnetically stirring at a constant temperature for 5h, cooling to room temperature, adding N-methylglucamine into the reactor, simultaneously heating to react to 80 ℃, magnetically stirring at a constant temperature for 1h, cooling to room temperature, adding a sodium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent in the embodiment 4.

Preparing the guanidine gum fracturing fluid: slowly adding 0.3 part of guar gum into 99.675 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.02 part of sodium hydroxide, 0.5 part of potassium chloride, 0.5 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the cross-linking agent in example 4 is added into the base fluid of the fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 140 ℃, and the shearing rate is 170s^-1Under the condition, the fracturing fluid is sheared for 60min, the viscosity of the fracturing fluid can be kept at 103mPa & s, and the use concentration of the guanidine gum is obviously reduced.

Example 5

The composition of the crosslinking agent provided in this example was the same as the crosslinking agent of example 1, except that boric acid was used instead of borax.

Preparation of the crosslinking agent: adding ethylene glycol and boric acid into a reactor, magnetically stirring for 10min, heating to 155 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 163 ℃, magnetically stirring at the constant temperature for 3h, cooling to room temperature, adding sorbitol into the reactor, heating to react to 105 ℃, magnetically stirring at the constant temperature for 0.5h, cooling to room temperature, adding a sodium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent in the embodiment 5.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the cross-linking agent in the embodiment 5 is added into the base fluid of the fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition, the fracturing fluid is sheared for 60min, the viscosity of the fracturing fluid can be kept at 75mPa & s, and the use concentration of the guanidine gum is obviously reduced.

Example 6

This example provides the same crosslinker composition as example 1, but with a different order of addition.

Preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 100 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 120 ℃, magnetically stirring at a constant temperature for 3h, cooling to room temperature, adding sorbitol into the reactor, heating to react to 50 ℃, magnetically stirring at a constant temperature for 1h, cooling to room temperature, adding glyoxal into the reactor, stirring for 1h, adding a sodium hydroxide aqueous solution, uniformly stirring, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent in the embodiment 6.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the cross-linking agent of example 6 is added to the fracturing fluid base fluid and mixed evenly to form the low-concentration guanidine gum fracturing fluid. By usingThe HAAKE rheometer is used for testing the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the testing temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition, the fracturing fluid is sheared for 60min, the viscosity of the fracturing fluid can be kept at 58mPa & s, and the use concentration of the guanidine gum is obviously reduced.

Comparative example 1

The crosslinking agent provided in this comparative example had the same composition as the crosslinking agent of example 1 except that tetraethylpentamine was omitted.

Preparation of the crosslinking agent: adding glycol and borax into a reactor, magnetically stirring for 20min, heating to 100 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, adding sorbitol into the reactor, simultaneously heating to react to 50 ℃, magnetically stirring at a constant temperature for 1h, cooling to room temperature, adding a sodium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, and cooling to room temperature to obtain a light yellow product, namely the boron crosslinking agent of comparative example 1.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the crosslinking agent in comparative example 1 was added to the base fracturing fluid, and the mixture was stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 37 mPas.

Comparative example 2

The cross-linking agent provided in this comparative example was the same as the cross-linking agent of example 1, except that sorbitol was omitted.

Preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 100 ℃, magnetically stirring at a constant temperature to completely separate water, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 120 ℃, magnetically stirring at a constant temperature for 3h, cooling to room temperature, adding a sodium hydroxide aqueous solution into the reactor, uniformly stirring, adding glyoxal, stirring for 1h, cooling to room temperature, obtaining a light yellow product, wherein a part of precipitate is the boron crosslinking agent in comparative example 2.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the cross-linking agent of the comparative example is added into the base fluid of the fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition, the viscosity of the fracturing fluid can be kept at 17 mPas after shearing for 60 min.

Comparative example 3

The crosslinking agent provided in this comparative example was the same as the crosslinking agent of example 1 except that the 20% aqueous sodium hydroxide solution was omitted.

Preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 100 ℃, completely separating water by constant-temperature magnetic stirring, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 120 ℃, then magnetically stirring at constant temperature for 3h, cooling to room temperature, adding sorbitol into the reactor, simultaneously heating to react to 50 ℃, magnetically stirring at constant temperature for 1h, cooling to room temperature, then adding glyoxal into the reactor, stirring for 1h, cooling to room temperature, obtaining a light yellow product, wherein a part of precipitate is the boron crosslinking agent in comparative example 3.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the crosslinking agent in comparative example 3 is added to the base fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 13 mPas.

Comparative example 4

The composition of the crosslinking agent provided in this comparative example was the same as that of the crosslinking agent of example 1 except that 40% by weight of glyoxal was omitted.

Preparation of the crosslinking agent: adding ethylene glycol and borax into a reactor, magnetically stirring for 20min, heating to 100 ℃, completely separating water by constant-temperature magnetic stirring, cooling to room temperature, slowly adding tetraethylpentamine into the reactor, heating to react to 120 ℃, then magnetically stirring at constant temperature for 3h, cooling to room temperature, adding sorbitol into the reactor, simultaneously heating to react to 50 ℃, then magnetically stirring at constant temperature for 1h, cooling to room temperature, then adding a sodium hydroxide aqueous solution into the reactor, and uniformly stirring to obtain a light yellow product, namely the boron crosslinking agent in comparative example 4.

Preparing the guanidine gum fracturing fluid: slowly adding 0.12 part of guar gum into 99.18 parts of water under the stirring condition, and stirring for 20-30 min; adding 0.005 part of sodium hydroxide, 0.5 part of potassium chloride, 0.3 part of cleanup additive and 0.05 part of bactericide into the mixture, and uniformly stirring the mixture to obtain a fracturing fluid base fluid; 0.5 part of the crosslinking agent in comparative example 4 is added to the base fracturing fluid, and the mixture is stirred and mixed uniformly to form the low-concentration guanidine gum fracturing fluid. The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, the fracturing fluid is sheared for 60min under the condition of the shearing rate of 170s & lt-1 & gt, and the viscosity of the fracturing fluid can be kept at 23mPa & s.

Comparative example 5

The components of the cross-linking agent provided in this comparative example were the same as those of the cross-linking agent preparation and the guanidine gum fracturing fluid preparation of example 1, except that borax was 20 parts.

The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition, the viscosity of the fracturing fluid can be kept at 32 mPas after shearing for 60 min.

Comparative example 6

The components of the cross-linking agent provided in this comparative example were the same as those of the cross-linking agent preparation and the guanidine gum fracturing fluid preparation of example 1, except that 60 parts of ethylene glycol was used.

The HAAKE rheometer is adopted to test the temperature resistance and the shear resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shear rate is170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 39 mPas.

Comparative example 7

The cross-linking agent provided in this comparative example was prepared in the same manner as in example 1 except that 15 parts of tetraethylpentamine were used as the cross-linking agent and the guanidine gum fracturing fluid were prepared.

The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 38 mPas.

Comparative example 8

The components of the cross-linking agent provided in this comparative example were the same as those of the cross-linking agent preparation and the guanidine gum fracturing fluid preparation of example 1, except that sorbitol was 10 parts.

The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 37 mPas.

Comparative example 9

The components of the crosslinking agent provided in this comparative example were the same as those of the crosslinking agent prepared in example 1 and the guanidine gum fracturing fluid prepared, except that 6 parts of a 20 wt% aqueous solution of sodium hydroxide was used.

The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition, the viscosity of the fracturing fluid can be kept at 26 mPas after shearing for 60 min.

Comparative example 10

The components of the crosslinking agent provided in this comparative example were the same as those of the crosslinking agent preparation and the guanidine gum fracturing fluid preparation of example 1, except that 2 parts of the 40 wt% aqueous glyoxal solution was used.

The HAAKE rheometer is adopted to test the temperature resistance and the shearing resistance of the fracturing fluid of the embodiment, the test temperature is 20 ℃, and the shearing rate is 170s^-1Under the condition of shearing for 60min, the viscosity of the fracturing fluid can be kept at 28 mPas.

From the above, it can be seen that the guanidine gum used in the guanidine gum fracturing fluids prepared in examples 1-5 of the present invention is significantly reduced in concentration and maintains good viscosity as compared to comparative examples 1-10. In comparative examples 1-10, the same guar concentration as in example 1 was used, but the viscosity requirements of the guar fracturing fluid were not met.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:

the low-concentration guanidine gum fracturing fluid system prepared by the invention realizes effective reduction of the guanidine gum concentration by preparing the efficient boron crosslinking agent, has good temperature resistance, shear resistance and sand carrying performance, effectively reduces the residue content, effectively reduces the reservoir damage, and has the advantages of improving the reservoir modification effect and saving the cost.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A boron crosslinker composition, characterized in that the boron crosslinker composition comprises, in parts by weight:

2. the boron crosslinker composition of claim 1, wherein the boron compound is either or both of boric acid and borax.

3. The boron crosslinker composition of claim 1, wherein the liquid organic solvent is an alcohol solvent, preferably the alcohol solvent is any one or more of ethylene glycol, butanol, pentanol, hexanol.

4. The boron crosslinker composition of claim 1, wherein the solid polyol is any one or more of sorbitol, pentaerythritol, dipentaerythritol, and N-methylglucamine.

5. The boron crosslinker composition of claim 1, wherein the base is provided as an alkali solution, preferably an alkali solution having a concentration of 20-50 wt.%, more preferably either or both of an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution having a concentration of 20-50 wt.%.

6. A method for producing a boron crosslinking agent, characterized in that the boron crosslinking agent is produced from the boron crosslinking agent composition according to any one of claims 1 to 5.

7. The method of manufacturing according to claim 6, comprising:

step S1: mixing an organic solvent with a boron compound to obtain a first mixture;

step S2: mixing tetraethyl pentamine with the first mixture to obtain a second mixture;

step S3: mixing a polyol with the second mixture to obtain a third mixture; and

step S4: and mixing alkali, glyoxal and the third mixture to obtain the boron crosslinking agent.

8. The method for preparing a composite material according to claim 7, wherein the step S1 includes:

mixing the organic solvent with the boron compound to obtain a first premix; and

heating the first premix to a first temperature under magnetic stirring, and carrying out magnetic stirring for 10-20 min at the first temperature to obtain the first mixture, wherein the first temperature is 100-150 ℃.

9. The method for preparing a composite material according to claim 7, wherein the step S2 includes:

cooling the first mixture to a second temperature, wherein the second temperature is 25-35 ℃;

adding the tetraethylpentamine to the first mixture at the second temperature to obtain a second premix;

under the magnetic stirring, heating the second premix to a third temperature, and carrying out magnetic stirring for 3-5 h at the third temperature to obtain the second mixture, wherein the third temperature is 120-160 ℃.

10. The method for preparing a composite material according to claim 7, wherein the step S3 includes:

cooling the second mixture to a fourth temperature, wherein the fourth temperature is 25-35 ℃;

adding said polyol to said second mixture at said fourth temperature to provide a third premix;

under the magnetic stirring, heating the third premix to a fifth temperature, and carrying out magnetic stirring for 0.5-1 h at the fifth temperature to obtain a third mixture, wherein the fifth temperature is 50-100 ℃.

11. The method for preparing a composite material according to claim 7, wherein the step S4 includes:

cooling the third mixture to a sixth temperature, wherein the sixth temperature is 25-35 ℃;

adding the base and the glyoxal to the third mixture at the sixth temperature under magnetic stirring to obtain the boron crosslinker.

12. A boron crosslinking agent characterized by being produced by the production method according to any one of claims 6 to 11.

13. A guanidine gum fracturing fluid composition comprising guanidine gum, water, a crosslinking agent, and a pH adjusting agent, wherein the crosslinking agent is the boron crosslinking agent of claim 12.

14. The guanidine gum fracturing fluid composition of claim 13, wherein the composition comprises, by weight, 0.12-0.3 parts of the guanidine gum, 0.2-0.5 parts of the crosslinking agent, 0.005-0.02 parts of the pH adjusting agent, and 99.18-99.675 parts of water.

15. The guanidine gum fracturing fluid composition of claim 14, wherein the composition optionally comprises an anti-swelling agent, a cleanup additive, and a biocide, preferably wherein the composition optionally comprises, in parts by weight:

0.5-2 parts of an anti-swelling agent;

0.3-1 part of a cleanup additive; and

0.05-0.1 part of bactericide.

16. The guanidine gum fracturing fluid composition of claim 13, wherein the pH adjusting agent is a basic material, preferably one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.