Nanodrilling material for enhanced oil recovery and method of making and using same in low permeability reservoirs

Abstract

The application provides a nano oil displacement material for enhanced oil recovery, a preparation method thereof and a use method thereof in low-permeability oil reservoirs. The preparation method comprises the following steps: mixing tartaric acid, polyethylene polyamine, alkyl alcohol ether and water to perform a hydrothermal reaction, and performing freeze-drying on the product after the hydrothermal reaction to obtain the nano oil displacement material. The weight ratio of the tartaric acid, the polyethylene polyamine and the alkyl alcohol ether is 1:2-4:3-5. The preparation method is easy to operate, and the raw materials are cheap and easy to obtain. In particular, the obtained nano oil displacement material has a small size, high interfacial activity and good wetting regulation capacity, and can exhibit a significant synergistic effect in combination with CO2 flooding in low-permeability oil reservoirs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil displacement agents, and particularly relates to a nano oil displacement material for improving oil recovery, a preparation method thereof and a use method thereof in low-permeability oil reservoirs. BACKGROUND

[0002] The nano oil displacement material is a chemical substance prepared by using nanotechnology and used for improving the oil recovery of oil and gas fields. The basic principle thereof is to use the special physical and chemical properties of nano materials to improve the flowability and recoverability of crude oil. The nano oil displacement material generally refers to a material with a size of 1-100 nm in at least one dimension, and these materials exhibit special properties due to their unique size effect. These properties include but are not limited to improving the flowability of fluids, changing the wettability of rock surfaces, and enhancing the separation efficiency between crude oil and water.

[0003] According to literature reports, some nano materials, such as silicon dioxide, titanium oxide and aluminum oxide, have potential applications in improving recovery. However, most nano oil displacement materials have the problem of large particle size, which may cause the blockage of nano-scale pore throats in low-permeability oil reservoirs. At the same time, most nano materials have low surface interfacial activity, and in order to obtain higher surface activity, a surface modifier is often used to modify the surface of the nano material, for example, a silane coupling agent is used to modify nano silicon dioxide. The above modification process will inevitably increase the production cost and reduce the stability of the nano material. In addition, in addition to the above nano materials, amphiphilic Janus nanoparticles, as a kind of asymmetric material, have also attracted much attention, but the preparation process of Janus nanoparticles is complicated and the production cost is high, which limits their application in improving recovery.

[0004] Low-permeability oil reservoirs refer to oil reservoirs with a rock permeability of less than 0.1 millidarcy, and have small porosity, poor permeability, high crude oil viscosity and low reservoir pressure. This type of oil reservoir is difficult to develop, has low recovery, and requires special techniques such as horizontal wells, hydraulic fracturing, etc. The development cost is high, the environmental risk is large, and the water resource consumption is large. Therefore, the low-cost preparation of nano oil displacement materials suitable for low-permeability oil reservoirs is a current research hotspot. SUMMARY

[0005] In order to solve the above technical problems, the purpose of the present application is to provide a nano oil displacement material for improving oil recovery, a preparation method thereof and a use method thereof in low-permeability oil reservoirs, which has small size, high interfacial activity and strong wetting control ability, and can be better applied to low-permeability oil reservoirs to improve oil recovery.

[0006] To achieve the above object, the present application provides a preparation method of a nano oil displacement material for enhanced oil recovery, which comprises: mixing tartaric acid, polyethylene polyamine, alkyl alcohol ether and water to perform hydrothermal reaction, and performing freeze drying on the product after the hydrothermal reaction to obtain the nano oil displacement material. The weight ratio of the tartaric acid, the polyethylene polyamine and the alkyl alcohol ether is 1:2-4:3-5.

[0007] In some optional embodiments, the polyethylene polyamine is selected from one or more than two combinations of diethylene triamine, triethylene tetramine and tetraethylene pentamine.

[0008] In some optional embodiments, the alkyl alcohol ether comprises one or more than two combinations of AEO-3, AEO-7 and AEO-9.

[0009] Further, the reaction temperature of the hydrothermal reaction is 140-200℃, and the reaction time of the hydrothermal reaction is 8-24h.

[0010] Further, the ratio of the total weight of the tartaric acid, the polyethylene polyamine and the alkyl alcohol ether to the weight of the water is 5-20:100, i.e. (the weight of the tartaric acid + the weight of the polyethylene polyamine + the weight of the alkyl alcohol ether) / the weight of the water = 5-20:100.

[0011] The present application also provides a nano oil displacement material for enhanced oil recovery, which is prepared by the aforementioned preparation method.

[0012] Further, the particle size of the nano oil displacement material is 3-10nm.

[0013] Further, the nano oil displacement material makes the interfacial tension between the crude oil and the water below 10 -1 mN / m.

[0014] The present application also provides a use method of the aforementioned nano oil displacement material for enhanced oil recovery in low-permeability oil reservoirs (rock permeability is lower than 0.1mD), which comprises: adding the nano oil displacement material into injection water.

[0015] Further, in the injection water, the mass concentration of the nano oil displacement material is 0.1-1%. The nano oil displacement material of the present application can be directly diluted with water and used, or mixed with other surfactants (such as sodium dodecyl sulfate, sodium α-alkenyl sulfonate, sodium lauryl alcohol polyoxyethylene ether sulfate, etc.) or polymers (such as partially hydrolyzed polyacrylamide, sodium carboxymethyl cellulose, xanthan gum, etc.) and used to further improve the enhanced oil recovery.

[0016] The application further provides a method for using the aforementioned nanometer oil displacement material for enhanced oil recovery in a low-permeability oil reservoir, which comprises: using a gaseous CO2 and nanofluid alternated slug injection method, wherein the nanofluid is a water solution with a mass concentration of 0.1-1% of the nanometer oil displacement material.

[0017] As an effective enhanced oil recovery method, CO2 flooding is widely used in oil and gas field development engineering. However, when CO2 and water are used as slugs, the reservoir heterogeneity is sensitive: high-permeability layers are prone to gas channeling, which reduces sweep efficiency and affects the implementation effect of the engineering. Therefore, finding a slug liquid with oil displacement and anti-gas channeling functions to replace water, thereby inhibiting gas channeling and optimizing flow, and improving sweep efficiency, will further reduce costs and improve oil recovery. The nanofluid and CO2 alternated injection of the application not only can significantly inhibit CO2 gas channeling, but also significantly improve the oil recovery of low-permeability oil reservoirs based on the physical and chemical properties of the nanometer oil displacement agent itself.

[0018] To sum up, the application has the following beneficial effects: the application uses tartaric acid, polyethylene polyamine and alkyl alcohol ether as raw materials, realizes carbonization through hydrothermal reaction, and in-situ forms a high-performance oil displacement material. The particle size of the oil displacement material is small, which can be better applied to low-permeability oil reservoirs. At the same time, the oil displacement material can be dissolved in water and most common organic solvents, and has excellent interfacial activity, which can greatly reduce the interfacial tension between crude oil and water. When CO2 is alternately injected, CO2 gas channeling can be significantly inhibited, thereby more effectively improving oil recovery. In addition, the application can realize the preparation of the above-mentioned oil displacement material through one-step hydrothermal reaction. The preparation method is simple, easy to operate, and the raw materials are cheap and easy to obtain, which can prepare nanometer oil displacement materials at low cost. Compared with existing nanometer oil displacement materials, the industrial application prospect is better. DETAILED DESCRIPTION

[0019] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the application, the technical solutions of the application are described in detail as follows, but it cannot be understood as limiting the implementable scope of the application.

[0020] In the following examples, tartaric acid, polyethylene polyamine and alkyl alcohol ether are purchased from Aladdin Reagent Co., Ltd.

[0021] Example 1

[0022] The embodiment provides a preparation method of a nanometer oil displacement material, which comprises the following steps:

[0023] Take 1.0 g tartaric acid, 2.0 g triethylene tetramine, 5.0 g AEO-9 into a volume of 100 mL of polytetrafluoroethylene stainless steel high-pressure reactor, add 75 mL of deionized water, ultrasonic for 2 min to mix the raw materials and deionized water uniformly. Put the sealed reactor in the oil bath pot and heat at 140℃ for 24h. When the high-pressure reactor is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0024] Example 2

[0025] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0026] Take 1.0 g tartaric acid, 3.0 g triethylene tetramine, 4.0 g AEO-9 into a volume of 100 mL of polytetrafluoroethylene stainless steel high-pressure reactor, add 80 mL of deionized water, ultrasonic for 2 min to mix the raw materials and deionized water uniformly. Put the sealed reactor in the oil bath pot and heat at 200℃ for 8h. When the high-pressure reactor is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0027] Example 3

[0028] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0029] Take 1.0 g tartaric acid, 4.0 g triethylene tetramine, 3.0 g AEO-9 into a volume of 100 mL of polytetrafluoroethylene stainless steel high-pressure reactor, add 50 mL of deionized water, ultrasonic for 2 min to mix the raw materials and deionized water uniformly. Put the sealed reactor in the oil bath pot and heat at 180℃ for 12h. When the high-pressure reactor is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0030] Example 4

[0031] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0032] Take 1.0 g tartaric acid, 4.0 g triethylene tetramine, 3.0 g AEO-9 into a volume of 100 mL of polytetrafluoroethylene stainless steel high-pressure reactor, add 50 mL of deionized water, ultrasonic for 2 min to mix the raw materials and deionized water uniformly. Put the sealed reactor in the oil bath pot and heat at 180℃ for 12h. When the high-pressure reactor is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0033] Example 5

[0034] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0035] 1.0 g of tartaric acid, 4.0 g of tetraethylenepentamine and 3.0 g of AEO-3 are weighed into a stainless steel high-pressure reaction kettle made of polytetrafluoroethylene with a volume of 100 mL, 50 mL of deionized water is added, and the raw materials and the deionized water are uniformly mixed through ultrasonic treatment for 2 min. The sealed reaction kettle is placed in an oil bath at 180 ℃ and heated for 12 h. When the high-pressure reaction kettle is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0036] Example 6

[0037] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0038] 1.0 g of tartaric acid, 4.0 g of triethylenetetramine and 3.0 g of AEO-9 are weighed into a stainless steel high-pressure reaction kettle made of polytetrafluoroethylene with a volume of 100 mL, 100 mL of deionized water is added, and the raw materials and the deionized water are uniformly mixed through ultrasonic treatment for 2 min. The sealed reaction kettle is placed in an oil bath at 200 ℃ and heated for 8 h. When the high-pressure reaction kettle is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0039] Example 7

[0040] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0041] 1.0 g of tartaric acid, 4.0 g of triethylenetetramine and 3.0 g of AEO-9 are weighed into a stainless steel high-pressure reaction kettle made of polytetrafluoroethylene with a volume of 100 mL, 50 mL of deionized water is added, and the raw materials and the deionized water are uniformly mixed through ultrasonic treatment for 2 min. The sealed reaction kettle is placed in an oil bath at 140 ℃ and heated for 24 h. When the high-pressure reaction kettle is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0042] Example 8

[0043] The embodiment provides a preparation method of a nano oil displacement material, which comprises the following steps:

[0044] 1.0 g of tartaric acid, 4.0 g of triethylenetetramine and 3.0 g of AEO-9 are weighed into a stainless steel high-pressure reaction kettle made of polytetrafluoroethylene with a volume of 100 mL, 50 mL of deionized water is added, and the raw materials and the deionized water are uniformly mixed through ultrasonic treatment for 2 min. The sealed reaction kettle is placed in an oil bath at 160 ℃ and heated for 18 h. When the high-pressure reaction kettle is cooled to room temperature, 10 mL of the reaction product system is freeze-dried to obtain the nano oil displacement material.

[0045] Comparative Example 1

[0046] Petroleum sulfonate, purchased from Hubei Huada Fine Chemical Co., Ltd.

[0047] Performance test:

[0048] (1) Particle size determination: The oil displacement agent in the examples was prepared into an oil displacement agent solution with a mass fraction of 0.05% by using water, and the particle size of the nano oil displacement material was determined by using a dynamic light scattering instrument. The test results are shown in Table 1.

[0049] (2) Interfacial tension determination method: The oil displacement agent in the examples and comparative examples was prepared into an oil displacement agent water system with a mass fraction of 0.5% by using mineralized water (50000 mg / L NaCl and 5000 mg / L CaCl2), and the interfacial tension between the oil displacement agent water system and the oil phase (the oil phase was No. 3 aviation kerosene) was determined by using a rotary drop interfacial tension instrument at 60°C and 6000 r / min. The test results are shown in Table 1.

[0050] (3) Crude oil recovery determination method: Referring to the test method in the literature Li, Lin, Xiao-Ming Jin, Jia Chen, Zizhao Wang, Yining Wu, Mingwei Zhao and Caili Dai. “Anionic surfactant with enhanced interfacial wettability control capability for residual oil development.” Colloids and Surfaces A: Physicochemical and Engineering Aspects (2022): n. pag.

[0051] Enhanced oil recovery = crude oil recovery of the oil displacement system tested in the examples and comparative examples (the oil displacement agent in the examples and comparative examples was prepared into an oil displacement agent water system with a mass fraction of 0.5% by using mineralized water (50000 mg / L NaCl and 5000 mg / L CaCl2)) - crude oil recovery obtained by water flooding test (water flooding test refers to directly injecting water to displace oil after the core is saturated with oil, and the ratio of oil production to saturated oil volume is the crude oil recovery of the water flooding test). The test results are shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055] The nano oil displacement material prepared by the method has a particle size of less than 10 nm, an oil-water interfacial tension of less than 10 mN / m, and can effectively improve the oil recovery rate of a low-permeability oil reservoir. -1 mN / m, can effectively improve the oil recovery rate of a low-permeability oil reservoir.

[0056] Example 9

[0057] The embodiment provides a method for improving recovery rate by combining CO2 and nano-fluid displacement, which comprises the following steps:

[0058] First, 0.1 PV of CO2 gas (pressure 15 MPa, flow rate 0.5 mL / min) is injected, and then 0.1 PV of nano-fluid (including 0.5 wt% of the nano oil displacement material synthesized in Example 1, prepared by using formation water, flow rate 0.5 mL / min) is injected. The above-mentioned CO2 and nano-fluid slug injection is repeated for 3 times, and the total injection amount is 0.6 PV. After the alternating cycle is completed, 1.0 PV of the oil displacement agent with mineralized water (flow rate 0.5 mL / min) is injected, and the experiment is stopped when the outlet water content is greater than 98%, and the oil recovery rate is calculated (oil recovery rate = the ratio of the volume of the oil collected from the outlet end in the core experiment to the volume of the oil initially saturated in the core).

[0059] Comparative Example 2

[0060] The comparative example provides a method for improving recovery rate by combining CO2 displacement and water displacement, which comprises the following steps:

[0061] 0.1 PV of CO2 gas (pressure 15 MPa, flow rate 0.5 mL / min) is injected, and then 0.1 PV of formation water (flow rate 0.5 mL / min) is injected. The above-mentioned CO2 and the oil displacement agent with mineralized water slug injection is repeated for 3 times, and the total injection amount is 0.6 PV. After the alternating cycle is completed, 1.0 PV of formation water (flow rate 0.5 mL / min) is injected, and the experiment is stopped when the outlet water content is greater than 98%, and the oil recovery rate is calculated.

[0062] Comparative Example 3

[0063] The comparative example provides a method for improving recovery rate by combining CO2 and surfactant displacement, which comprises the following steps:

[0064] 0.1 PV of CO2 gas (pressure 15 MPa, flow rate 0.5 mL / min) is injected, and then 0.1 PV of a surfactant solution (including 0.5 wt% of the zwitterionic surfactant CAB-35, prepared by using formation water) is injected at a flow rate of 0.5 mL / min. The above-mentioned CO2 and surfactant solution slug injection is repeated for 3 times, and the total injection amount is 0.6 PV. After the alternating cycle is completed, 1.0 PV of formation water (flow rate 0.5 mL / min) is injected, and the experiment is stopped when the outlet water content is greater than 98%, and the oil recovery rate is calculated.

[0065] The enhanced oil recovery of the examples and comparative examples of different displacement system combination flooding is shown in Table 2.

[0066] Table 2

[0067]

[0068] The combination of CO2 flooding and nano oil displacement agent flooding exhibits a significant synergistic effect in the development of low permeability reservoirs, and the synergistic mechanism is embodied in: the nano oil displacement agent can enhance the contact area of CO2 and crude oil, promote the dissolution and diffusion of CO2; at the same time, the injection pressure of CO2 can push the nano oil displacement agent into the low permeability area, expand the swept volume and improve the sweep efficiency; the low permeability reservoir has strong heterogeneity, CO2 is easy to rush along the high permeability channel, while the nano oil displacement agent can block the high permeability channel by adsorption, make CO2 turn to the micro non-swept area with high oil saturation, expand the swept volume, and delay gas channeling. The small size of the nano oil displacement agent can enter the micro-nano pore, and through the "active oil seeking" mechanism, the oil film is stripped and the residual oil in the pore blind end is reduced. The swelling effect of CO2 further promotes the nano oil displacement agent to penetrate into smaller pores.

Claims

1. A method for preparing a nano-drilling oil material for enhanced oil recovery, wherein, The application relates to a nano oil displacement material and a preparation method thereof. The tartaric acid, polyethylene polyamine, alkyl alcohol ether and water are mixed to carry out a hydrothermal reaction, and the product after the hydrothermal reaction is freeze-dried to obtain the nano oil displacement material. The weight ratio of the tartaric acid, the polyethylene polyamine and the alkyl alcohol ether is 1:2-4:3-5. The polyethylene polyamine is selected from one or more than two combinations of diethylene triamine, triethylene tetramine and tetraethylene pentamine. The alkyl alcohol ether comprises one or more than two combinations of AEO-3, AEO-7 and AEO-9.

2. The method for preparing nano-displacement materials for enhanced oil recovery according to claim 1, wherein, The reaction temperature of the hydrothermal reaction is 140-200 DEG C.

3. The method for preparing nano-displacement materials for enhanced oil recovery according to claim 2, wherein, The reaction time of the hydrothermal reaction is 8-24 hours.

4. The method of claim 1, wherein the nano-displacement oil material for enhanced oil recovery is prepared by the steps of: The ratio of the total weight of the tartaric acid, the polyethylene polyamine and the alkyl alcohol ether to the weight of the water is 5-20:

100.

5. A nano-displacement oil material for enhanced oil recovery, wherein, The nano oil displacement material is prepared by the preparation method in any one of claims 1 to 4.

6. The enhanced oil recovery nanodrilling fluid of claim 5, wherein, The particle size of the nano oil displacement material is 3-10 nm.

7. A method of using the nanodrilling oil material for enhanced oil recovery as claimed in claim 5 or 6 in low permeability reservoirs, wherein, The application further relates to an injection water containing the nano oil displacement material. The nano oil displacement material is added into injection water, and the mass concentration of the nano oil displacement material in the injection water is 0.1-1%.

8. A method of using the nanodrilling oil material for enhanced oil recovery as claimed in claim 5 or 6 in low permeability reservoirs, wherein, The application further relates to a method for injecting oil displacement fluid into oil reservoirs. The nano fluid is a water solution with a mass concentration of the nano oil displacement material of 0.1-1%.

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