Shale oil based rock debris recycling profile control agent as well as preparation method and application thereof

Abstract

The invention discloses a shale oil-based rock debris recycling profile control agent and a preparation method and application thereof, and relates to the technical field of oilfield chemicals, oilfield development and solid waste recycling. The profile control agent is prepared from the following components in percentage by weight: 5 to 10 percent of sodium salt, 15 to 20 percent of alkyl ammonium chloride, 15 to 25 percent of nonionic surfactant, 15 to 20 percent of viscoelastic surfactant, 20 to 30 percent of water and 10 to 15 percent of ethanol. The shale oil-based rock debris can be disintegrated and dispersed into 1-100m graded particles, and after the graded particles are mixed with water according to a preset proportion, the apparent viscosity measured by a rotational viscometer is 20-100mPas under the conditions that the temperature is 25 DEG C and the shear rate is 100. The preparation method adopts a step-by-step dissolution and specific sequential compounding process. In site construction, high-permeability reservoirs are mixed with water according to the ratio of 1: 0.6, low-permeability reservoirs are mixed according to the ratio of 1: 1.8, stratum ducts can be effectively blocked, and resource utilization of shale oil base rock debris is achieved.

Description

Technical Field

[0001] This invention application relates to the fields of oilfield chemicals, oilfield development and solid waste resource utilization, and in particular to a shale oil-based rock cuttings resource utilization profile control agent, its preparation method and application. Background Technology

[0002] With the continuous expansion of shale oil extraction, the amount of shale oil-based cuttings generated during the extraction process has exploded. A single shale oil well can produce 800-1500 tons of cuttings. Under the background of large-scale development, the environmental treatment of cuttings has become a key bottleneck restricting the industry's development. At present, the mainstream treatment methods for shale oil-based cuttings in the industry focus on incineration and pyrolysis. However, both of these methods have serious environmental hazards and resource waste problems, and no technology has yet been applied to the field of oilfield profile control.

[0003] From the perspective of incineration, the heavy oil and organic additives contained in shale oil-based rock cuttings release large amounts of toxic and harmful gases such as sulfur oxides, nitrogen oxides, and dioxins during high-temperature incineration. Among them, dioxins are highly carcinogenic and bioaccumulative; even trace emissions can remain in the atmosphere for a long time, harming human health through respiration and the food chain. At the same time, the ash produced by incineration still contains heavy metals (such as chromium, lead, and mercury) and unburned oil. If directly landfilled, these can easily seep into the deeper soil layers with rainwater, causing heavy metal pollution in the soil and oil pollution in groundwater systems, disrupting the balance of the surrounding ecosystem. Furthermore, the incineration process consumes a large amount of energy, which does not meet the requirements of green and low-carbon development.

[0004] While pyrolysis can recover some oil and gas resources compared to incineration, the process requires high temperatures (usually 300-600℃) and closed conditions, resulting in high equipment investment costs and high energy consumption. In addition to oil and gas, pyrolysis products also produce oily coke residue and acidic wastewater. The coke residue needs further treatment to meet discharge standards, and if the acidic wastewater is discharged directly without deep treatment, it will corrode soil structure, acidify water bodies, and cause surrounding vegetation to wither and aquatic organisms to die. Furthermore, if the operation is not properly controlled during pyrolysis, local overheating can easily occur, leading to incomplete decomposition of organic pollutants and the production of toxic polycyclic aromatic hydrocarbons such as benzo[a]pyrene, which also poses serious environmental risks. Moreover, pyrolysis can only recover a portion of the rock fragments, failing to fully utilize their characteristics of originating from and being well-compatible with the strata, resulting in low resource utilization.

[0005] Meanwhile, during reservoir water injection development, high-permeability reservoirs, due to their well-developed pore structure and high permeability, are prone to water channeling. Injected water, without effectively displacing crude oil, rapidly flows through high-permeability channels to production wells, leading to a significant reduction in oil recovery. Therefore, profile control technology is urgently needed to seal these high-permeability channels and improve the water injection profile. Currently, most profile control agents used in the industry are prepared from traditional chemical raw materials (such as polymers and inorganic gels). On the one hand, the raw material procurement costs are high, increasing the economic burden on oilfield development; on the other hand, these profile control agents have poor compatibility with formation lithology, easily leading to problems such as sealing failure and short-term effectiveness. Furthermore, they cannot be combined with the processing needs of shale oil-based cuttings, failing to achieve a circular economy model of "treating waste with waste."

[0006] Therefore, the existing methods of incinerating and pyrolyzing shale oil-based cuttings pose serious environmental hazards, and the industry has not yet applied them to the field of profile control. At the same time, traditional profile control agents are costly and have poor compatibility, making it difficult to meet the dual needs of environmentally friendly cuttings treatment and efficient reservoir development.

[0007] Therefore, developing a resource-based profile control agent that can efficiently disintegrate shale oil-based rock cuttings into graded particles and a mixed system with controllable viscosity and density adapted to reservoir porosity, thereby achieving the dual goals of hazardous waste resource utilization and oilfield profile control and efficiency enhancement, has become a key technical challenge that urgently needs to be solved. Summary of the Invention

[0008] This application provides a shale oil-based rock cuttings resource utilization profile control agent, its preparation method, and its application. It also presents a method for treating oil-based rock cuttings, combining hazardous waste treatment with oilfield development. This invention enables the processing of oil-based rock cuttings into a graded particle system. During on-site construction, by adjusting the water addition ratio, different viscosities and densities can be achieved, adapting to reservoirs with varying permeability.

[0009] The first aspect, expressed as a percentage by weight, consists of the following components: 5-10% sodium salt, 15-20% alkyl ammonium chloride, 15-25% nonionic surfactant, 15-20% viscoelastic surfactant, 20-30% water, and 10-15% ethanol.

[0010] In conjunction with the first aspect, in one possible implementation, the sodium salt is a mixture of sodium tripolyphosphate, sodium metasilicate, and sodium carbonate; the mass ratio of the mixture of sodium tripolyphosphate, sodium metasilicate, and sodium carbonate is 2:2:1.

[0011] In conjunction with the first aspect, in one possible implementation, the alkylammonium chloride is a mixture of dodecyl dimethyl benzyl ammonium chloride and octadecylamine polyoxyethylene ether quaternary ammonium salt, wherein the dodecyl dimethyl benzyl ammonium chloride accounts for 9% of the total weight and the octadecylamine polyoxyethylene ether quaternary ammonium salt accounts for 6% of the total weight.

[0012] In conjunction with the first aspect, in one possible implementation, the nonionic surfactant is a mixture of fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ester and ethanol, wherein the total concentration of the fatty alcohol polyoxyethylene ether and the fatty acid polyoxyethylene ester is in the range of 6000-10000 ppm, the mass ratio of the fatty alcohol polyoxyethylene ether to ethanol is 1:1, and the mass ratio of the fatty acid polyoxyethylene ester to ethanol is 3:1 or 4:1.

[0013] In conjunction with the first aspect, in one possible implementation, the nonionic surfactant contains fatty alcohol polyoxyethylene ether in a weight ratio of 1:1 to fatty acid polyoxyethylene ester.

[0014] In conjunction with the first aspect, in one possible implementation, the viscoelastic surfactant is made from octadecylamine and a polyoxyethylene substance in a mass ratio of 1:2, wherein the octadecylamine is N-octadecyl-1,3-propanediamine and the polyoxyethylene substance is polyoxyethylene isocyanate.

[0015] Secondly, embodiments of this application provide a method for preparing a shale oil-based cuttings profile control agent for resource utilization, comprising: Weigh each component reagent, turn on the stirred tank, add water first, then add sodium salt and stir to dissolve, then add alkyl ammonium chloride, nonionic surfactant, and ethanol and stir evenly, then add viscoelastic surfactant, continue to stir evenly and then discharge the material. The components reagent are expressed as weight percentage as follows: sodium salt 8%, alkyl ammonium chloride 18%, nonionic surfactant 20%, viscoelastic surfactant 18%, water 25%, and ethanol 11%. The preparation process of the profile control agent includes: mixing a pre-prepared sodium salt solution, a surfactant solution, a viscoelastic surfactant solution, an alkyl ammonium chloride solution, and water in sequence; wherein the order of material addition is: first add the surfactant solution, then add the viscoelastic surfactant solution, then add the alkyl ammonium chloride solution, then add the sodium salt solution, and finally add the water.

[0016] In conjunction with the second aspect, in one possible implementation, the sodium salt is dissolved in water in the following order: first, sufficient water is added to dissolve sodium metasilicate, then sodium tripolyphosphate is dissolved, and finally sodium carbonate is dissolved. The amount of water added is 2-3 times the mass of the sodium salt, so that the mass fraction of the solution is 25-33%. After dissolution, stirring is continued for 2-3 hours, and the discharge temperature is controlled at 25-40℃.

[0017] In conjunction with the second aspect, in one possible implementation, the preparation process of the viscoelastic surfactant includes: Step 1: Dehydrate octadecylamine and polyoxyethylene isocyanate separately by drying them under vacuum of 0.08-0.1 MPa and temperature of 80-100℃ for 2-3 hours to remove moisture from the raw materials; the number average molecular weight of the polyoxyethylene isocyanate is 500-1000. Step 2: Mix N,N-dimethylformamide and toluene at a volume ratio of 1:2 to obtain a mixed solvent. The amount of the mixed solvent is 1-2 times the total mass of octadecylamine and polyoxyethylene isocyanate. Step 3: Add the dehydrated octadecylamine and polyoxyethylene isocyanate to the reactor at a mass ratio of 1:2, then add the mixed solvent. Under nitrogen protection, control the reaction temperature at 0-25℃, the stirring speed at 200-300rpm, and react for 2-4 hours. Step 4: Add palladium acetate catalyst to the reaction system in step 3. The amount of palladium acetate catalyst added is 0.01-0.03% of the total mass of octadecylamine and polyoxyethylene isocyanate. Heat to 60-75℃, maintain a stirring rate of 200-300 rpm, and continue the reaction for 4-6 hours. Step 5: After the reaction is complete, the mixture is distilled under a vacuum of 0.08-0.1 MPa and a temperature of 70-90℃ to remove the mixed solvent and obtain crude viscoelastic surfactant. The crude viscoelastic surfactant is mixed with ethanol at a mass ratio of 1:1 and stirred evenly to obtain the viscoelastic surfactant.

[0018] Thirdly, embodiments of this application provide an application of a shale oil-based cuttings resource-based profile control agent in reservoir water injection development profile control, as described in the first aspect or any possible implementation of the first aspect. For high-permeability reservoirs, the ratio of the profile control agent to water is 1:0.6, the density of the profile control fluid is 1.44 g / ml, and the viscosity is 35-55 mPa·s; for low-permeability reservoirs, the ratio of the profile control agent to water is 1:1.8, the density of the profile control fluid is 1.23 g / ml, and the viscosity is 15-25 mPa·s. The profile control agent is used to disintegrate and disperse shale oil-based cuttings into graded particles of 1-100 µm.

[0019] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: This application provides a shale oil-based cuttings resource utilization profile control agent, its preparation method, and its application. The profile control agent, by weight percentage, consists of 5-10% sodium salt, 15-20% alkyl ammonium chloride, 15-25% nonionic surfactant, 15-20% viscoelastic surfactant, 20-30% water, and 10-15% ethanol. It can disintegrate and disperse shale oil-based cuttings into 1-100µm graded particles. After mixing with cuttings in a preset ratio, the mixture is subjected to a reaction at 25°C and a shear rate of 100... Under these conditions, the apparent viscosity measured by a rotational viscometer is 50-100 mPa•s. Its preparation employs a stepwise dissolution and specific sequential compounding process. For high-permeability reservoirs, it is mixed with water at a ratio of 1:0.6, and for low-permeability reservoirs, it is mixed at a ratio of 1:1.8. This effectively seals formation pores, enabling the resource utilization of shale oil-based cuttings, and is suitable for water injection development and profile control in shale oil reservoirs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic flowchart illustrating a method for preparing a shale oil-based cuttings profile control agent for resource recovery, provided in an embodiment of this application. Figure 2 This is a particle size distribution diagram of processed shale oil-based rock fragments provided in an embodiment of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The following description of some technologies involved in the embodiments of this application is provided to aid understanding and should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, some descriptions of well-known functions and structures are omitted in the following description.

[0024] like Figure 1 As shown, Figure 1 This is a flowchart illustrating a method for preparing a shale oil-based cuttings profile control agent for resource recovery, as provided in this application. Figure 1 The steps shown are implemented to obtain the following embodiment: Example 1: The profile control agent formulation is prepared according to the following weight percentages: Sodium salt: 5% (sodium tripolyphosphate 2%, sodium metasilicate 2%, sodium carbonate 1%); Alkyl ammonium chloride: 15% (dodecyl dimethyl benzyl ammonium chloride 9%, octadecylamine polyoxyethylene ether quaternary ammonium salt 6%); Nonionic surfactant: 15% (fatty alcohol polyoxyethylene ether 7%, fatty acid polyoxyethylene ester 8%); Viscoelastic surfactant: 15%; Water: 30%; Ethanol: 10%.

[0025] In the preparation of the sodium salt solution, weigh 20g of sodium tripolyphosphate, 20g of sodium metasilicate, and 10g of sodium carbonate according to the above proportions, and add 125g of water (2.5 times the mass of the sodium salt, with a solution mass fraction of 29%). First, dissolve the sodium metasilicate by stirring at 300 rpm for 30 minutes until completely dissolved; then add the sodium tripolyphosphate and continue stirring for 30 minutes; finally, add the sodium carbonate and stir for 30 minutes. After dissolution, continue stirring for 2.5 hours, and control the discharge temperature at 30℃.

[0026] In the preparation of the nonionic surfactant solution, 70g of fatty alcohol polyoxyethylene ether was weighed and mixed with 70g of ethanol at a mass ratio of 1:1, and stirred at 30 rpm for 20 minutes; 80g of fatty acid polyoxyethylene ester was weighed and mixed with 27g of ethanol at a mass ratio of 3:1, and stirred at 30 rpm for 20 minutes. The two solutions were then mixed to a total concentration of 7500ppm and stirred for 1 hour.

[0027] In the preparation process of viscoelastic surfactants, the preparation is carried out according to steps 1-5: Step 1: Weigh 50g of N-octadecyl-1,3-propanediamine and 100g of polyoxyethylene isocyanate (number average molecular weight 800), and dehydrate them under vacuum of 0.09MPa and 90℃ for 2.5 hours.

[0028] Step 2: Mix 50g of N,N-dimethylformamide and 100g of toluene at a volume ratio of 1:2 as a solvent, and use an amount that is 1.5 times the total mass of the raw materials.

[0029] Step 3: Add the dehydrated raw material to the reactor, add the mixed solvent, and stir at 15°C and 250 rpm for 3 hours under nitrogen protection.

[0030] Step 4: Add 0.15g of palladium acetate (0.01% of the total mass of raw materials), heat to 70℃, and stir at 250rpm for 5 hours.

[0031] Step 5: Distill to remove the solvent under a vacuum of 0.09 MPa and 80°C. Mix the crude product with 75 g of ethanol at a ratio of 1:1 and stir until homogeneous.

[0032] In the preparation of the profile control agent, weigh out each component reagent, turn on the stirring tank (300 rpm), first add 30% water, then add sodium salt solution and stir to dissolve, then add alkyl ammonium chloride, nonionic surfactant solution and ethanol and stir for 30 minutes, then add viscoelastic surfactant, continue stirring for 1 hour and then discharge.

[0033] The profile control agent and shale oil-based cuttings were mixed at a mass ratio of 1:4 and stirred at 300 rpm for 40 minutes. A laser particle size analyzer determined the cuttings particle size to be 1-50 μm, with continuous gradation; a rotational viscometer was used at 25℃ and a shear rate of 100... The apparent viscosity of the mixed system was 52 mPa•s. For high-permeability reservoirs, the profile control agent and water were mixed at a ratio of 1:0.6, resulting in a profile control fluid density of 1.44 g / ml, a viscosity of 40 mPa•s, and a plugging rate of 68%. For low-permeability reservoirs, a mixture of 1:1.8 was used, resulting in a density of 1.23 g / ml, a viscosity of 20 mPa•s, and a plugging rate of 62%.

[0034] Example 2: The profile control agent formulation is prepared according to the following weight percentages: Sodium salt: 8% (sodium tripolyphosphate 3%, sodium metasilicate 3%, sodium carbonate 2%); Alkyl ammonium chloride: 18% (dodecyl dimethyl benzyl ammonium chloride 10%, octadecylamine polyoxyethylene ether quaternary ammonium salt 8%); Nonionic surfactant: 20% (fatty alcohol polyoxyethylene ether 10%, fatty acid polyoxyethylene ester 10%); Viscoelastic surfactant: 18%; Water: 25%; Ethanol: 11%.

[0035] The preparation of each component and the profile control agent were carried out according to the method in Example 1, wherein 160g of water (twice the mass of sodium salt) was added to dissolve the sodium salt, and the total concentration of nonionic surfactant was 8000ppm.

[0036] The profile control agent is mixed with shale oil-based cuttings at a ratio of 1:5, with a cuttings particle size of 55-90 μm; the apparent viscosity of the mixture is 78 mPa•s. When applied to high-permeability reservoirs, the viscosity is 45 mPa•s, with a plugging rate of 72%; when applied to low-permeability reservoirs, the viscosity is 22 mPa•s, with a plugging rate of 65%.

[0037] Example 3: The profile control agent formulation is prepared according to the following weight percentages: Sodium salt: 10% (sodium tripolyphosphate 4%, sodium metasilicate 3%, sodium carbonate 3%); Alkyl ammonium chloride: 20% (dodecyl dimethyl benzyl ammonium chloride 12%, octadecylamine polyoxyethylene ether quaternary ammonium salt 8%); Nonionic surfactant: 25% (fatty alcohol polyoxyethylene ether 12%, fatty acid polyoxyethylene ester 13%); Viscoelastic surfactant: 20%; Water: 20%; Ethanol: 15%.

[0038] The preparation of each component and the profile control agent were carried out according to the method in Example 1. Sodium salt was dissolved by adding 225g of water (2.25 times the mass of sodium salt), and the total concentration of nonionic surfactant was 9000ppm.

[0039] The profile control agent is mixed with shale oil-based cuttings at a ratio of 1:6, with a cuttings particle size of 60-100 μm; the apparent viscosity of the mixture is 98 mPa•s. When applied to high-permeability reservoirs, the viscosity is 50 mPa•s, with a plugging rate of 70%; when applied to low-permeability reservoirs, the viscosity is 25 mPa•s, with a plugging rate of 63%.

[0040] The profile control agent of this application is required to be a well-dispersible suspension. The appearance of oil-based rock cuttings after being treated with profile control agents of different concentrations and with stirring processes is shown in Table 1: Table 1: Appearance of oil-based rock cuttings

[0041] Table 1 shows that samples 1 and 2 had insufficient profile modifier concentration, resulting in incomplete surface modification and disintegration of rock fragments. Sample 3 had insufficient stirring time, leading to incomplete dispersion. Sample 4 achieved good dispersion. A 10g sample from sample 4 was added to 90ml of water, and the pH was tested to be 7, meeting the standard requirements.

[0042] Shale has a density of 2.2-2.8 g / cm³. After crushing, rock fragments have a wide density range, varying greatly depending on the degree of crushing and viscosity compared to other substances. The profile control fluid technology in this application requires a density of 0.9-1.25 g / cm³. Therefore, water needs to be added to the rock fragments to adjust their density, and 200 g of rock fragments was used for testing.

[0043] Table 2: Density Adjustment Test

[0044] As shown in Table 2, water needs to be added up to 90% of the weight of the rock chips to adjust the density to a suitable range. Furthermore, the water should be added in small amounts at first and then gradually increased in multiple additions. Adding enough water at once will result in uneven dispersion and a low rock chip disintegration rate.

[0045] Apparent viscosity is mainly related to the proportion of oil-based mud in the cuttings and also to the amount of profile control fluid added. Shale cuttings typically contain very little oil-based mud and will not have excessively high viscosity. The viscosity of the well-dispersed sample (number 8) was tested to be 25 mPa·s, which meets the standard requirements. Suspension stability is a very important indicator of profile control fluid. If the index is too low, particles will settle too quickly, resulting in a shallow profile control depth and potential deposition in transport vehicles and pipelines, causing production accidents. Cuttings treatment will be adjusted based on the process system in number 8.

[0046] Table 3: Suspension Stability Index

[0047] As shown in Table 3, increasing the profile control agent and increasing the stirring time will fully disperse and disintegrate the rock fragments, and the settling velocity of the particles will decrease under the action of electrostatic repulsion and viscoelastic surfactant.

[0048] The plugging rate is related to particle size and sedimentation suspension index, with particle size being the key factor. If the particle size is too large, the permeability of the plugging pores will be too high, leading to plugging failure and rendering the process ineffective. Therefore, the treatment process should be further optimized based on Sequence 11 to meet the plugging rate requirements.

[0049] Table 4: Blocking Rate

[0050] As shown in Table 4, increasing the profile control agent to 5%, increasing the stirring speed to 400 rpm, and increasing the stirring time to 6 hours significantly improves the plugging rate. This is because the rock cuttings are further broken down and fragmented under the influence of the profile control agent and mechanical stirring, and the overall suspension of the profile control fluid is enhanced, which can achieve deep profile control and expand the affected area.

[0051] The key indicator for improving profile control is the plugging rate, and the core control factor for the plugging rate is the particle size. Good profile control agents have a graded distribution and a moderate particle size, which can achieve deep profile control. Figure 2 A particle size distribution diagram of processed shale oil-based rock cuttings provided in this application embodiment, such as... Figure 2 As shown, the particle size of this profile control agent is graded, mainly ranging from 10.94µm to 70.88µm. The distribution range is wide, but the overall particle size is small, making it suitable for profile control processes.

[0052] This application demonstrates how the synergistic effect of sodium salt, alkyl ammonium chloride, nonionic surfactant, and viscoelastic surfactant can stably disintegrate shale oil-based rock cuttings into continuously graded particles of 1-100 μm (1-50 μm in Example 1, 55-90 μm in Example 2, and 60-100 μm in Example 3). Furthermore, the mixed system is maintained at 25°C and a shear rate of 100... Under the specified conditions, the apparent viscosity was controlled within the range of 52-98 mPa•s, fully meeting the basic requirements for the dispersibility and rheological properties of cuttings in profile modification operations. By optimizing key process parameters (such as the stepwise dissolution sequence of sodium salt, the ratio control of nonionic surfactant and ethanol, and the reaction temperature and vacuum degree of viscoelastic surfactant), and strictly following the compounding sequence of "surfactant solution → viscoelastic surfactant → alkyl ammonium chloride → sodium salt solution → water", the profile modification agent system was ensured to be uniformly dispersed without stratification, and the performance deviation rate of each batch of product was ≤5%.

[0053] To verify the performance of the profile control agent prepared in this application, this application uses the above-mentioned profile control agent in a defined ratio and compounding order as an example, and uses ratios exceeding the defined ratios and compounding orders different from those in this application as comparative examples, as detailed below.

[0054] Comparative Example 1: The sodium salt ratio exceeds the specified range.

[0055] The sodium salt content is 15% (exceeding the 5-10% range), the water content is 20%, and the remaining components and proportions are the same as in Example 2.

[0056] After being mixed with rock cuttings, the rock cuttings have a particle size of 210-300 μm, the apparent viscosity of the mixed system is 42 mPa•s, the high-permeability reservoir plugging rate is 50%, and the low-permeability reservoir plugging rate is 45%.

[0057] Comparative Example 2: Lacking viscoelastic surfactant.

[0058] The composition includes a non-viscoelastic surfactant, 43% water, and the remaining components and proportions are the same as in Example 2.

[0059] The apparent viscosity of the mixed system is 20 mPa•s, with significant rock cuttings settling. The plugging rate of high-permeability reservoirs is 45%, and the plugging rate of low-permeability reservoirs is 40%.

[0060] Comparative Example 3: Incorrect compounding order.

[0061] The compounding sequence in the preparation process is sodium salt solution → surfactant solution → viscoelastic surfactant → alkyl ammonium chloride → water, and the remaining compounding sequence is the same as in Example 2.

[0062] The system is stratified, with an apparent viscosity of 35 mPa•s for the mixed system, a high-permeability reservoir plugging rate of 52%, and a low-permeability reservoir plugging rate of 48%.

[0063] The embodiments in this application strictly follow the limitations of the implementation methods described herein. The prepared profile control agent can disintegrate rock cuttings into 1-100µm graded particles, and the apparent viscosity of the mixed system meets the requirements, demonstrating good sealing effects in different reservoirs. The comparative examples, deviating from the limitations of this application, show a significant decrease in performance.

[0064] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A profile control agent for shale oil-based rock cuttings resource utilization, characterized in that, The reagents include the following weight percentages: sodium salt 5-10%, alkyl ammonium chloride 15-20%, nonionic surfactant 15-25%, viscoelastic surfactant 15-20%, water 20-30%, and ethanol 10-15%.

2. The profile control agent according to claim 1, characterized in that, The sodium salt is a mixture of sodium tripolyphosphate, sodium metasilicate, and sodium carbonate; the mass ratio of the mixture of sodium tripolyphosphate, sodium metasilicate, and sodium carbonate is 2:2:

1.

3. The profile control agent according to claim 1, characterized in that, The alkyl ammonium chloride is a mixture of dodecyl dimethyl benzyl ammonium chloride and octadecylamine polyoxyethylene ether quaternary ammonium salt, wherein the dodecyl dimethyl benzyl ammonium chloride accounts for 9% of the total weight and the octadecylamine polyoxyethylene ether quaternary ammonium salt accounts for 6% of the total weight.

4. The profile control agent according to claim 1, characterized in that, The nonionic surfactant is a mixture of fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ester and ethanol, wherein the total concentration of the fatty alcohol polyoxyethylene ether and the fatty acid polyoxyethylene ester is in the range of 6000-10000 ppm, the mass ratio of the fatty alcohol polyoxyethylene ether to ethanol is 1:1, and the mass ratio of the fatty acid polyoxyethylene ester to ethanol is 3:1 or 4:

1.

5. The profile control agent according to claim 4, characterized in that, The weight ratio of fatty alcohol polyoxyethylene ether to fatty acid polyoxyethylene ester in the nonionic surfactant is 7:

8.

6. The profile control agent according to claim 1, characterized in that, The viscoelastic surfactant is made from octadecylamine and a polyoxyethylene substance in a mass ratio of 1:2, wherein the octadecylamine is N-octadecyl-1,3-propanediamine, and the polyoxyethylene substance is polyoxyethylene isocyanate.

7. A method for preparing the shale oil-based cuttings resource-based profile control agent according to any one of claims 1-6, characterized in that, include: Weigh each component reagent, turn on the stirred tank, add water first, then add sodium salt and stir to dissolve, then add alkyl ammonium chloride, nonionic surfactant, and ethanol and stir evenly, then add viscoelastic surfactant, continue to stir evenly and then discharge the material. The components reagent are expressed as weight percentage as follows: sodium salt 8%, alkyl ammonium chloride 18%, nonionic surfactant 20%, viscoelastic surfactant 18%, water 25%, and ethanol 11%. The preparation process of the profile control agent includes: mixing a pre-prepared sodium salt solution, a surfactant solution, a viscoelastic surfactant solution, an alkyl ammonium chloride solution, and water in sequence; wherein the order of material addition is: first add the surfactant solution, then add the viscoelastic surfactant solution, then add the alkyl ammonium chloride solution, then add the sodium salt solution, and finally add the water.

8. The preparation method according to claim 7, characterized in that, The sodium salt is dissolved in water in the following order: first dissolve sodium metasilicate, then dissolve sodium tripolyphosphate, and finally dissolve sodium carbonate. The amount of water added is 2-3 times the mass of the sodium salt, so that the mass fraction of the solution is 25-33%. After dissolution, continue stirring for 2-3 hours, and control the discharge temperature at 25-40℃.

9. The preparation method according to claim 7, characterized in that, The preparation process of the viscoelastic surfactant includes: Step 1: Dehydrate octadecylamine and polyoxyethylene isocyanate separately by drying them under vacuum of 0.08-0.1 MPa and temperature of 80-100℃ for 2-3 hours to remove moisture from the raw materials; the number average molecular weight of the polyoxyethylene isocyanate is 500-1000. Step 2: Mix N,N-dimethylformamide and toluene at a volume ratio of 1:2 to obtain a mixed solvent. The amount of the mixed solvent is 1-2 times the total mass of octadecylamine and polyoxyethylene isocyanate. Step 3: Add the dehydrated octadecylamine and polyoxyethylene isocyanate to the reactor at a mass ratio of 1:2, then add the mixed solvent. Under nitrogen protection, control the reaction temperature at 0-25℃, the stirring speed at 200-300rpm, and react for 2-4 hours. Step 4: Add palladium acetate catalyst to the reaction system in step 3. The amount of palladium acetate catalyst added is 0.01-0.03% of the total mass of octadecylamine and polyoxyethylene isocyanate. Heat to 60-75℃, maintain a stirring rate of 200-300 rpm, and continue the reaction for 4-6 hours. Step 5: After the reaction is complete, the mixture is distilled under a vacuum of 0.08-0.1 MPa and a temperature of 70-90℃ to remove the mixed solvent and obtain crude viscoelastic surfactant. The crude viscoelastic surfactant is mixed with ethanol at a mass ratio of 1:1 and stirred evenly to obtain the viscoelastic surfactant.

10. The application of the shale oil-based cuttings resource utilization profile control agent according to any one of claims 1-6 in water injection development profile control of shale oil reservoirs, characterized in that, For high-permeability reservoirs, the ratio of the profile control agent to water is 1:0.6, the density of the profile control fluid is 1.44 g / ml, and the viscosity is 35-55 mPa·s; for low-permeability reservoirs, the ratio of the profile control agent to water is 1:1.8, the density of the profile control fluid is 1.23 g / ml, and the viscosity is 15-25 mPa·s. The profile control agent is used to disintegrate and disperse shale oil-based rock cuttings into graded particles of 1-100 µm.

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