Self-aggregation weak-consolidation multifunctional sand control agent and application thereof

Abstract

The invention discloses a self-aggregation weak-consolidation multifunctional sand control agent and application thereof, and belongs to the technical field of oil gas chemistry. The sand control agent is prepared by simply mixing 0.2-0.6 part by weight of a hydrophobic modifier, 0.6-1.2 parts by weight of a chemical modifier and 2-4 parts by weight of an organic solvent. The hydrophobic modifier is selected from one or more of the following components: methacryloyloxy silane, heptadecafluorodecyl trimethoxy silane, amino alkyl polydimethylsiloxane, octamethylcyclotetrasiloxane, poly [3-((2-aminoethyl) amino) propyl] methyl (dimethyl) siloxane, gamma-propyl trimethoxy silane and the like; the chemical modifier is a compound containing alkenyl. The sand control agent can be used for coating modification of a proppant, self-aggregation and clustering in water are realized, and solidified sand is formed through polymerization of the alkenyl-containing compound on the surface, so that the sand control effect is achieved; the sand control agent can also be directly added into fracturing fluid and permeates into a stratum to form a hydrophobic consolidation layer, so that the effect of stabilizing a rock wall surface is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas chemistry, in particular to a self-aggregating weakly consolidated multifunctional sand control agent and application thereof. Background Art

[0002] Hydraulic fracturing has become an important means of increasing production in the development of oil and gas reservoirs. During the fracturing process, proppant is transported to the designated position to support the crack to form an oil and gas flow channel. However, after the fracturing construction is completed, the high-speed flow of the return fluid may drive the proppant in the crack to flow back to the wellbore. Especially for large-scale horizontal well fracturing, the return fluid volume is large and the return time is long, resulting in serious proppant backflow. The backflow of proppant will cause damage to the wellbore and ground equipment, causing serious safety hazards. At the same time, the reduction of proppant in the fracture reduces the effective support area of ​​the fracture, affecting the fracturing transformation effect. Therefore, taking effective sand control measures is of great significance to ensure safe production and improve the fracturing effect.

[0003] At present, the main sand control measures include mechanical sand control technology, chemical sand control technology, and composite sand control technology. Chemical sand control mainly uses chemical materials to achieve the cementation of the sand layer, which is convenient for construction and easy for later operations. Commonly used chemical sand control technologies mainly use resin sand control agents, fibers, composite cement mortars, etc. as sand control materials. Traditional chemical sand control technology is mainly based on the process technology of spraying sand control agents with proppants to modify, adding sand to the tail of the modified proppants, and realizing the consolidation of proppants near the wellbore. For some weakly cemented formations (such as coal rock and weakly cemented sandstone), their own strength is low, and sand particles are more likely to fall off under formation pressure and fluid scouring. Therefore, it is more necessary to stabilize the fracture wall to form an effective sand control surface. At present, cemented sand control agents that can be injected into the formation with fracturing fluid to stabilize rocks are still rare, and there are limited relevant literature that can be consulted. For example, patent CN 115873587 A discloses a composite chemical anti-backflow additive and a method for preventing proppant backflow, that is, a method of using a small amount of curing resin and a degradable fiber composite to improve sand control ability and reduce the impact on conductivity and damage to equipment. CN 110423604A discloses a sand control proppant and its preparation method and application, through the carboxyl-containing organic matter can be open-ring reaction with epoxy resin in the cross-linking reaction film forming process, so that the carboxyl-containing organic matter and epoxy resin, epoxy resin and epoxy resin are cross-linked, strengthen the bonding force between proppants, and improve the adhesion between resin film and supporting aggregate. CN 110317594 A discloses a sand control agent that realizes sand self-aggregation, through the synergistic effect between its chemical agents, sand self-aggregation is achieved, and the formation sand can be wrapped into a ball and fixed at the corresponding position of the formation, which significantly improves the consolidation effect, increases the scope of action, and can also play a good sand consolidation effect on fine silt. Although the above-mentioned sand control methods have been optimized for sand control technology, the existing sand control agents and sand control technologies still have problems such as complex processes, harsh application conditions, and poor sand consolidation effects. Summary of the invention

[0004] In view of the problems of complex process and poor sand consolidation effect in current sand control methods, the present invention provides a self-aggregating weakly consolidated multifunctional sand control agent and application thereof.

[0005] The self-aggregating weakly consolidated multifunctional sand control agent provided by the present invention is prepared by simply stirring and mixing the following raw material components in the following weight proportions: 0.2-0.6 parts of hydrophobic modifier, 0.6-1.2 parts of chemical modifier and 2-4 parts of organic solvent.

[0006] The hydrophobic modifier is selected from one or more of methacryloxysilane, heptadecafluorodecyltrimethoxysilane, aminoalkylpolydimethylsiloxane, octamethylcyclotetrasiloxane, poly[3-((2-aminoethyl)amino)propyl]methyl(dimethyl)siloxane, γ-propyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-glycidyloxypropyltrimethoxysilane; The chemical modifier is an alkenyl-containing compound.

[0007] Preferably, the chemical modifier is selected from one or more of epoxidized polybutadiene, isoprene, epoxy-terminated polybutadiene, α-methylstyrene, vinyltriethoxysilane, vinyltri(methylethoxy)silane, vinyltrichlorosilane, vinyltri(methoxyethoxy)silane, and vinylmethyldimethoxysilane.

[0008] The organic solvent is selected from one or more of petroleum ether, white oil, solvent oil, dimethyl sulfoxide, hexane, cyclohexane, toluene and xylene.

[0009] The present invention also provides an application method of the self-aggregating weakly consolidated multifunctional sand control agent, the steps of which are as follows: (1) The surface of the proppant is modified with a sand control agent to obtain an unactivated modified proppant. The modification method can be to mix the sand control agent with the proppant and stir for 3 to 5 minutes, or to spray the sand control agent on the surface of the proppant. In this process, the molecules of the sand control agent solution have strong adsorption capacity and can quickly and stably attach to the proppant surface to wait for activation.

[0010] (2) Add unactivated modified proppant and activator to the fracturing fluid, and then inject it into the formation, where the proppant self-aggregates and consolidates to achieve the purpose of sand control. In the formation, the olefinic compounds on the surface of the modified proppant undergo covalent polymerization under the action of the activator, and physical and chemical reactions occur between the proppant particles to generate hydrophobic binding forces and covalent forces, which produce a capture effect to achieve self-aggregation and weak consolidation, further achieving efficient sand control during the fracturing process.

[0011] The activator is a directional activator, which is selected from one or more of azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0012] Preferably, in step (1), the weight ratio of the sand control agent to the proppant is (0.8-1.2): 100. The proppant is quartz sand or ceramsite.

[0013] Preferably, in step (2), the weight ratio of the fracturing fluid, the unactivated modified proppant, and the activator is 100:20:(0.075-0.1).

[0014] The present invention also provides another application method of the self-aggregating weakly consolidated multifunctional sand control agent: adding the sand control agent and the activator to the fracturing fluid, and then injecting it into the formation, wherein the sand control agent and the activator react in the formation to form a hydrophobic consolidation layer, thereby achieving the purpose of stabilizing the rock wall surface; the activator is selected from one or more of azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0015] Preferably, the weight ratio of the fracturing fluid, the sand control agent and the activator is 100:(2-10):(0.075-0.1).

[0016] The thickener of the fracturing fluid can be guar gum, linear polyacrylamide, hydrophobically associating polyacrylamide, viscoelastic surfactant, etc.

[0017] Compared with the prior art, the present invention is beneficial in that: (1) The sand control agent of the present invention can be used to modify the proppant, so that the proppant surface has hydrophobicity, self-aggregates into clusters in water, and the polymerization reaction of the olefin-containing compound on the proppant surface under the action of the activator forms consolidated sand, thereby achieving the sand control effect. It effectively solves the problems of the current sand control technology, such as the difficulty of proppant storage, too high consolidation strength, unsatisfactory sand control in low-temperature reservoirs, and failure of sand control in the later stage, and can effectively improve the fracture conductivity to achieve production increase transformation.

[0018] (2) The sand control agent can also be directly added to the fracturing fluid, pumped into the formation with the fracturing fluid, and penetrate into the formation to form a hydrophobic consolidation layer, effectively improving the rock cementation strength, reducing the sand production caused by rock spalling due to fluid scouring, and achieving the consolidation of rock fragments and the stabilization of the fracture wall. The sand control agent can not only play a hydrophobic and consolidation effect, but also has little effect on the permeability damage and fracture conductivity.

[0019] (3) The sand control agent of the present invention can achieve uniform modification of the proppant, has good compatibility with the fracturing fluid, is highly stable, and can achieve efficient sand control and formation rock stabilization at a formation temperature above 30°C.

[0020] (4) The sand control agent and the method for modifying the proppant of the present invention have a simple preparation process and can be obtained by mixing and stirring various raw materials. At the same time, the required raw materials are easy to obtain and the cost is low, so large-scale, safe and efficient production can be achieved.

[0021] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a physical picture of the sand control agent solution of Example 1 of the present invention.

[0023] Figure 2 The figures are the actual pictures of the proppant particles before and after modification of Example 1 of the present invention; (a) is the proppant before modification, and (b) is the proppant after modification.

[0024] Figure 3 This is a physical picture of the sand column in which the proppant is agglomerated and consolidated according to Example 1 of the present invention.

[0025] Figure 4 This is a real picture of the coal rock pillar formed by consolidating coal rock particles with the sand control agent of Example 4 of the present invention.

[0026] Figure 5 This is a schematic diagram of the sand control mechanism by which the sand control agent of the present invention promotes the proppant to self-aggregate and consolidate in the fracture. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] Example 1 Preparation of a self-aggregating weakly consolidated multifunctional sand control agent: Take 0.5 parts of γ-aminopropyl triethoxysilane, 1 part of vinyl triethoxysilane and 3 parts of cyclohexane by weight and add them into a stirrer; stir at a speed of 100 r / min for 5 minutes at room temperature to obtain an oil-soluble sand control agent solution. Figure 1 As shown, the sand control agent is a clear and transparent solution.

[0029] Application method of sand control agent: (1) Take 100 parts by weight of 20-40 mesh quartz sand proppant and 0.8 parts of oil-soluble sand control agent solution, add them into a stirrer and stir at a speed of 100 r / min for 1 min to obtain an unactivated modified proppant; the morphology of the proppant particles before and after modification is compared as shown in Figure 2 , (a) is the proppant before modification, and (b) is the proppant after modification.

[0030] (2) 20 parts by weight of unactivated modified proppant were taken into a stirrer, followed by the addition of 100 parts of polyacrylamide water-based fracturing fluid with a viscosity of 9 mPa·s and 0.08 parts of azobisisobutylamidine hydrochloride, and the mixture was stirred at a speed of 200 r / min for 5 min to obtain a mixed solution.

[0031] Performance test of the mixed solution: The mixed solution was placed in an oven at 50°C for 4 hours to achieve the final consolidation effect of the proppant. The sand column formed was as follows: Figure 3 shown.

[0032] Example 2 Preparation of a self-aggregating weakly consolidated multifunctional sand control agent: 0.6 parts of methacryloxysilane, 0.8 parts of isoprene and 3.5 parts of cyclohexane were added into a stirrer according to the mass ratio, and stirred at a speed of 100 r / min for 5 minutes at room temperature to obtain an oil-soluble sand control agent solution.

[0033] Application method of sand control agent: (1) taking 100 parts by weight of a 20-40 mesh quartz sand proppant, and spraying 1 part of an oil-soluble sand control agent solution evenly on the surface of the proppant to obtain an unactivated modified proppant; (2) 20 parts by weight of unactivated modified proppant were taken into a stirrer, followed by the addition of 100 parts of polyacrylamide water-based fracturing fluid with a viscosity of 9 mP·s and 0.085 parts of ammonium persulfate, and the mixture was stirred at a speed of 200 r / min for 5 min to obtain a mixed solution.

[0034] Performance test of the mixed liquid: After the mixed liquid is placed in an oven at 30°C for 6 hours, the final consolidation effect of the proppant is achieved and a sand column is formed.

[0035] Example 3 Preparation of a self-aggregating weakly consolidated multifunctional sand control agent: Take 0.4 parts of γ-glycidyloxypropyltrimethoxysilane, 0.9 parts of vinylmethyldimethoxysilane and 4 parts of dimethyl sulfoxide in parts by weight, add them into a stirrer, and stir at a speed of 100 r / min for 5 minutes at room temperature to obtain a sand control agent solution.

[0036] Application method of sand control agent: 100 parts of 9 mPa·s polyacrylamide water-based fracturing fluid were taken by weight, all the prepared sand control agent solution and 0.08 parts of ammonium persulfate were added to the fracturing fluid, and stirred at a speed of 100 r / min for 2 minutes to obtain a mixed solution.

[0037] Performance test of the mixed liquid: 100 parts of formation cuttings are taken by weight, added to the above mixed liquid, stirred at a speed of 200r / min for 5 minutes, and then placed in a 50°C oven for 4 hours to consolidate the cuttings and form sand columns.

[0038] Example 4 Preparation of a self-aggregating weakly consolidated multifunctional sand control agent: Take 0.5 parts of octamethylcyclotetrasiloxane, 1.0 parts of vinyltrichlorosilane and 3.8 parts of dimethyl sulfoxide in parts by weight, add them into a stirrer, and stir at a speed of 100 r / min for 2 minutes at room temperature to obtain a sand control agent solution.

[0039] Application method of sand control agent: 100 parts of 9 mPa·s polyacrylamide water-based fracturing fluid were taken by weight, all the prepared sand control agent solution and 0.08 parts of ammonium persulfate were added to the fracturing fluid, and stirred at a speed of 100 r / min for 2 minutes to obtain a mixed solution.

[0040] Performance test of the mixed solution: Take 100 parts of formation rock cuttings (coal rock particles) by weight, add them to the above mixed solution, stir at a speed of 200r / min for 5 minutes, and place them in a 50℃ oven for 4 hours to achieve consolidation of the rock cuttings to form a mixture as shown in the following figure. Figure 4 Sand column shown.

[0041] Comparative Example 1 100 parts by weight of polyacrylamide water-based fracturing fluid with a viscosity of 9 mPa·s and 20 parts by weight of 20-40 mesh quartz sand proppant were added into a stirrer and stirred at a rate of 200 r / min for 5 min to obtain a mixed solution.

[0042] The mixed solution was placed in an oven at 50 °C for 4 h, and the consolidation of the proppant was observed.

[0043] Comparative Example 2 Take 100 parts by weight of polyacrylamide water-based fracturing fluid with a viscosity of 9 mPa·s, 20 parts by weight of 20-40 mesh quartz sand proppant, and 0.08 parts by weight of azobisisobutylamidine hydrochloride, stir at a speed of 200 r / min for 5 min, then place it in a 50°C oven for 4 h to observe the consolidation of the proppant.

[0044] Comparative Example 3 According to the same method as in Example 1, a sand control agent solution is prepared, and the proppant is modified to obtain an unactivated modified proppant; the difference is that in the application method, in step (2), the activator azobisisobutyramidine hydrochloride is not added.

[0045] The obtained mixed solution was subjected to a performance test: the mixed solution was placed in an oven at 50°C for 4 hours, and the consolidation of the proppant was observed.

[0046] Comparative Example 4 According to the same method as in Example 4, a sand control agent solution was prepared; The application method of sand control agent is as follows: 100 parts of 9 mPa·s polyacrylamide water-based fracturing fluid were taken by weight, all the prepared sand control agent solution was added to the fracturing fluid, and stirred at a speed of 100 r / min for 2 minutes to obtain a mixed solution.

[0047] Performance test of the mixed liquid: Take 100 parts of formation cuttings by weight, add them to the above mixed liquid, stir at a speed of 200r / min for 5 minutes, place in a 50℃ oven for 4 hours, and observe the consolidation of the cuttings.

[0048] Related experimental methods and effect data: (1) Evaluation of sand column consolidation strength by ultrasonic vibration test The sand columns obtained by consolidation in the oven of Examples 1-4 and Comparative Examples 1-4 are placed in the central mesh area of ​​the ultrasonic oscillator, the ultrasonic oscillator is started and the time is recorded. Under the influence of ultrasonic waves, the sand particles on the sand columns will gradually be peeled off, causing the volume of the sand columns to gradually decrease. When the volume of the sand column drops to a certain critical point, so that it falls off from the mesh structure, it indicates that the sand column has been damaged, and the timing is stopped at this time. The time required for the entire process from the beginning of peeling to the final falling off of the sand column, that is, the collapse time of the sand column, can be used as an evaluation indicator to measure the self-polymerization performance of the modified proppant. The test results of the collapse time of the sand columns of Examples 1-4 and Comparative Examples 1-4 are shown in Table 1.

[0049] Table 1. Sand column collapse time test data of Examples 1-4 and Comparative Examples 1-4

[0050] From the collapse time of the proppant sand column in Examples 1 and 2, it can be seen that after the conventional quartz sand proppant is modified by the sand control agent of the present invention, it is kept at 30°C or higher in the fracturing fluid containing an activator for more than 4 hours, and an aggregated form (sand column) with a certain strength is formed through the aggregation effect of the proppant itself. From the collapse time of the consolidated cuttings column in Examples 3 and 4, it can be seen that the direct addition sand control agent consolidation method for formation cuttings can simply and efficiently consolidate and stabilize the formation cuttings.

[0051] The collapse time of the sand column in Comparative Example 1 is 0, which indicates that when no reagent is added, the original proppant has no self-aggregation property in the fracturing fluid and is in a free loose sand state in the fracturing fluid. The collapse time of the sand column in Comparative Example 2 is also 0, which indicates that when only the activator is added, the original proppant cannot achieve self-aggregation and consolidation in the fracturing fluid. Comparative Example 3 shows that when only the sand control agent is added without the activator, the self-aggregation of the proppant can be achieved, but a regular sand column cannot be formed. This is because the hydrophobic molecules in the sand control agent solution are adsorbed on the proppant surface, so that the hydrophobic association force is formed between the proppant particles to achieve self-aggregation, but its strength is greatly reduced. After adding the activator, the proppant can form a regular sand column in the fracturing fluid through self-aggregation, which proves that the activator can activate the olefinic compound attached to the proppant surface to undergo a new chemical covalent polymerization reaction, forming a covalent force different from the hydrophobic association force to achieve the self-aggregation and consolidation of the proppant particles. According to Comparative Example 4, when the sand control agent is directly added to consolidate the formation rock cuttings without adding an activator, its consolidation strength will be reduced. This is also because the activator can activate the olefin-containing compound in the sand control agent to undergo a new chemical covalent polymerization reaction to form a covalent force, thereby forming a hydrophobic consolidation layer, effectively improving the rock cementation strength, and reducing the sanding caused by rock spalling due to fluid scouring. It can be seen that the sand control agent of the present invention needs to be used in combination with an activator to achieve the best sand control effect.

[0052] The mechanism by which the sand control agent in the present invention promotes the proppant to self-aggregate and consolidate in the fracture to prevent sand is as follows: Figure 5 As shown, firstly, the surface of the proppant is modified by a sand control agent to obtain an unactivated modified proppant; the modified proppant and the activator are added to the fracturing fluid, which is injected into the formation along with the fracturing fluid, and the monolayer of the proppant surface is activated by the action of the activator under the formation, that is, the olefinic compounds on the surface of the proppant are activated to undergo a covalent polymerization reaction; physical hydrophobic association forces and chemical covalent forces are generated between the proppant particles, resulting in a capture effect to achieve a self-aggregation weak consolidation effect of the proppant, and achieve efficient sand control during the fracturing process.

[0053] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A self-aggregating weakly consolidated multifunctional sand control agent, characterized in that: The following raw material components in weight proportion are mixed by stirring: 0.2-0.6 parts of hydrophobic modifier, 0.6-1.2 parts of chemical modifier and 2-4 parts of organic solvent; The hydrophobic modifier is selected from one or more of methacryloxysilane, heptadecafluorodecyltrimethoxysilane, aminoalkylpolydimethylsiloxane, octamethylcyclotetrasiloxane, poly[3-((2-aminoethyl)amino)propyl]methyl(dimethyl)siloxane, γ-propyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-glycidyloxypropyltrimethoxysilane; The chemical modifier is an alkenyl-containing compound.

2. The self-aggregating weakly consolidated multifunctional sand control agent according to claim 1, characterized in that: The chemical modifier is selected from one or more of epoxidized polybutadiene, isoprene, epoxy-terminated polybutadiene, α-methylstyrene, vinyltriethoxysilane, vinyltri(methylethoxy)silane, vinyltrichlorosilane, vinyltri(methoxyethoxy)silane, and vinylmethyldimethoxysilane.

3. The self-aggregating weakly consolidated multifunctional sand control agent according to claim 1, characterized in that: The organic solvent is selected from one or more of petroleum ether, white oil, solvent oil, dimethyl sulfoxide, hexane, cyclohexane, toluene and xylene.

4. A method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to any one of claims 1 to 3, characterized in that: Here are the steps: (1) Modifying the proppant surface with a sand control agent to obtain an unactivated modified proppant; (2) Adding unactivated modified proppants and activators to the fracturing fluid and then injecting it into the formation, the proppants self-aggregate and consolidate in the formation to achieve the purpose of sand control; The activator is selected from one or more of azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

5. The method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to claim 4, characterized in that: In step (1), the method for modifying the surface of the proppant with the sand control agent is to mix the sand control agent with the proppant and stir for 3 to 5 minutes, or to spray the sand control agent on the surface of the proppant.

6. The method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to claim 5, characterized in that: In step (1), the weight ratio of the sand control agent to the proppant is (0.8-1.2):

100.

7. The method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to claim 5, characterized in that: The proppant is quartz sand or ceramsite.

8. The method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to claim 4, characterized in that: In step (2), the weight ratio of the fracturing fluid, the unactivated modified proppant, and the activator is 100:20:(0.075-0.1).

9. A method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to any one of claims 1 to 3, characterized in that: A sand control agent and an activator are added to the fracturing fluid, which is then injected into the formation, where the sand control agent reacts with the activator to form a hydrophobic consolidation layer, thereby stabilizing the rock wall surface; the activator is selected from one or more of azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

10. The method for applying the self-aggregating weakly consolidated multifunctional sand control agent according to claim 9, characterized in that: The weight ratio of the fracturing fluid, sand control agent and activator is 100: (2-10): (0.075-0.1).

Images