In-situ modification catalytic composite viscosity reducer for heavy oil exploitation at reservoir temperature and application thereof

Abstract

This invention belongs to the field of heavy oil extraction and petrochemical technology, specifically relating to an in-situ modified catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures and its application. The composite viscosity reducer comprises modified aluminum-pillared montmorillonite and ethanolamine; the mass ratio of modified aluminum-pillared montmorillonite to ethanolamine is 1:2; wherein the modified aluminum-pillared montmorillonite has an aluminum loading of 0.8 wt%, an interlayer spacing of 1.8~2.2 nm, and a specific surface area of ​​180~220 m². 2 / g. This invention achieves low-temperature viscosity reduction of heavy oil through a triple physicochemical synergistic mechanism of "interlayer intercalation expansion + Lewis acid coordination polarization + hydrogen bond association disruption," achieving a viscosity reduction rate of over 50% at 90℃. Compared with existing technologies, the composite viscosity reducer of this invention has a simple composition, low cost, and is environmentally friendly. It can be directly applied to heavy oil blocks with different physical properties and salinity levels, without requiring modification of existing oilfield wellbores and surface extraction equipment, resulting in extremely low barriers to industrialization.

Description

Technical Field

[0001] This invention belongs to the field of heavy oil extraction and petrochemical technology, specifically relating to an in-situ modifying catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures and its application. Background Technology

[0002] Heavy oil extraction faces the core challenges of high viscosity and poor fluidity. Traditional methods such as heating to reduce viscosity, diluting to reduce viscosity, and emulsification to reduce viscosity all suffer from high energy consumption, high costs, or difficulties in post-processing. Low-temperature hardening and viscosity reduction technology for heavy oil utilizes the reservoir's own temperature to trigger the reforming reaction, eliminating the need for additional heating and making it the most economical technical approach.

[0003] Among various low-temperature viscosity-reducing materials, montmorillonite, as a natural layered silicate mineral, possesses advantages such as a two-dimensional nanosheet structure, large specific surface area, abundant reserves, and low cost. The principle behind using montmorillonite for heavy oil viscosity reduction lies in the fact that nanosheets can penetrate into the gaps in asphaltene aggregates, expanding the stacked macromolecules; the polar basal surface can adsorb polar groups in asphalt and resins, and the hydrophobic chains extend outward to isolate heavy components, preventing molecular reassociation. However, conventional montmorillonite has a fixed interlayer spacing (approximately 1.2 nm) and limited pore capacity, making it difficult to achieve effective adsorption and dissociation of large molecular heavy components (asphaltene molecules are typically >2 nm in size).

[0004] In existing technologies, Chinese patent document CN107488248A uses organic quaternary ammonium salts to intercalate and modify montmorillonite before in-situ polymerization, which is a complex process requiring initiators and organic solvents. Chinese patent document CN116240006A uses organic intercalating agents and oxidants for multi-step modification, which poses safety risks and pore blockage problems. All of these technologies suffer from complex preparation processes, high costs, and viscosity-reducing effects dependent on the physical entanglement of polymer chains, making it difficult to achieve efficient and stable dissociation of heavy components in heavy oil under low-temperature conditions.

[0005] Therefore, developing a novel viscosity reducer that is simple in composition, easy to prepare, low in cost, and can effectively dissociate heavy components of heavy oil under low temperature conditions remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the problem of poor viscosity reduction effect of heavy oil at low temperatures (reservoir temperature) in existing technologies, this invention provides an in-situ catalytic composite viscosity reducer for heavy oil extraction at reservoir temperature and its application. This viscosity reducer is mainly composed of modified aluminum-pillared montmorillonite and ethanolamine in a fixed ratio. Under reservoir temperature conditions, through the dual synergistic effects of interlayer expansion and coordination dissociation, it can effectively reduce the degree of intermolecular association and aggregate structure stability of heavy components such as gums and asphaltenes in heavy oil, thereby achieving a significant reduction in the apparent viscosity of heavy oil and inhibiting viscosity rebound after viscosity reduction.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An in-situ modified catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures comprises modified aluminum-pillared montmorillonite and ethanolamine; the mass ratio of modified aluminum-pillared montmorillonite to ethanolamine is 1:2; the modified aluminum-pillared montmorillonite is an inorganic pillar-modified product obtained by hydroxyl aluminum ion exchange and high-temperature calcination of natural sodium-based montmorillonite; wherein the modified aluminum-pillared montmorillonite has an aluminum loading of 0.8 wt%, a layered structure with an interlayer spacing of 1.8~2.2 nm, and a specific surface area of ​​180~220 m². 2 / g.

[0008] Preferably, the particle size of the modified aluminum-pillared montmorillonite is less than 200 mesh.

[0009] Modified aluminum-pillared montmorillonite has a layered structure and mesoporous-macroporous composite channels, possessing ion exchange capacity, surface Lewis acid sites and interlayer confinement effect. It has no carbon-based structure and no electrical conductivity, and is only used for adsorbing and anchoring bitumen and polarizing CS / CN heteroatom bonds.

[0010] Preferably, the high-temperature roasting and shaping conditions are: high-temperature roasting at 450℃ for 2 hours.

[0011] A further preferred method is to prepare modified aluminum-pillared montmorillonite using an ion-exchange pillaring method, wherein the specific steps for exchanging interlayer sodium ions with aluminum hydroxyl ions are as follows: (a) Add sodium hydroxide solution dropwise to an aluminum salt solution, OH - With Al 3+ The molar ratio is (2.0~2.8):1; after the addition is complete, continue aging for 12~36h to obtain a clear and transparent aluminum hydroxide oligomer pillar solution; (b) The hydroxyl aluminum oligomer pillar liquid was added dropwise to a sodium-based montmorillonite suspension with a mass ratio of Al element to natural sodium-based montmorillonite dry powder of (0.5~1.2):100. After aging, the exchange and pillaring process of hydroxyl aluminum ions on sodium ions in the montmorillonite interlayer was completed.

[0012] Preferably, in step (a), both the dropping process and the aging process are carried out at 50~80℃ and 200~500rpm with a dropping rate of 1~2mL / min.

[0013] Preferably, in step (a), the concentration of the aluminum salt solution is 0.1~0.5 mol / L and the concentration of the sodium hydroxide solution is 0.2~1 mol / L.

[0014] Preferably, in step (b), the preparation method of the sodium-based montmorillonite suspension with a mass fraction of 5% is as follows: natural sodium-based montmorillonite is added to deionized water, stirred and swollen at a constant temperature of 50~80℃ for 10~14h, and then ultrasonically dispersed at a power of 200~500W for 10~60min to fully peel and disperse the montmorillonite sheets, thereby obtaining a uniform and stable sodium-based montmorillonite suspension.

[0015] Preferably, in step (b), the solution is slowly added dropwise to the montmorillonite suspension at a rate of 2-3 mL / min; the entire dropwise process is carried out at a constant temperature of 50-80°C and stirred at 100-300 rpm. After the dropwise addition is completed, the reaction is continued at a constant temperature and stirred for 6 hours. Then, stirring is stopped, and the solution is allowed to stand at 50-80°C for 10-14 hours to complete the exchange and pillaring process of aluminum hydroxide ions on sodium ions in the montmorillonite interlayer.

[0016] Ethanolamine is a small-molecule polar intercalation regulator, an analytical grade small-molecule polar nitrogen-containing organic compound with the molecular formula H2NCH2CH2OH and a boiling point of 170.8℃. It can be inserted into the layered framework of modified aluminum pillared montmorillonite through molecular diffusion and hydrogen bonding, expanding the interlayer spacing to 2.5~3.0 nm and increasing the pore capacity of the material. At the same time, the hydroxyl and amino groups contained in the molecule can form hydrogen bonds with the polar groups in the resin and asphaltenes molecules, weakening the intermolecular association forces.

[0017] This invention also provides the application of the above-mentioned viscosity reducer in the modification and viscosity reduction of heavy oil at reservoir temperatures. At reservoir temperatures, the composite viscosity reducer is formulated into a working fluid and injected into the target oil layer. After a well-steaming reaction, production is commenced. The viscosity reducer of this invention is suitable for conventional heavy oil and extra-heavy oil from different reservoir sources, with a viscosity range of 2000~800000 mPa·s at 50℃ and an asphaltene content of 2~26 wt%.

[0018] In the viscosity reducer described in this invention, modified aluminum-pillared montmorillonite and ethanolamine exert their effects through a multiple synergistic physicochemical mechanism involving "interlayer intercalation and expansion + Lewis acid coordination polarization + hydrogen bond association disruption". (1) Ethanolamine is inserted into the interlayer of modified aluminum-pillared montmorillonite, which significantly expands the interlayer spacing and provides sufficient space for diffusion and adsorption of macromolecular heavy components; (2) Lewis acid sites on the surface of modified aluminum-pillared montmorillonite (Al 3+ It coordinates with S and N heteroatoms in heavy molecules, polarizing and weakening the van der Waals forces and hydrogen bonds between molecules; (3) Free ethanolamine molecules form hydrogen bonds with polar groups on the surface of heavy components, breaking up the aggregate network of gums and asphaltenes. (4) The dissociated small molecules are uniformly dispersed in the oil phase. The adsorption effect of the modified aluminum pillar montmorillonite inhibits the secondary aggregation of heavy molecules, thus achieving long-term viscosity reduction.

[0019] The entire process is dominated by physicochemical adsorption and coordination, and belongs to a purely physicochemical quality improvement process.

[0020] Beneficial effects of the present invention Compared with the prior art, the present invention has at least the following technical effects: (1) The viscosity reducer has a very simple and fixed composition: it uses only two common chemical raw materials, without any other components. The formula is simple and clear, and there is zero error in on-site operation. No complicated compatibility testing is required.

[0021] (2) Safe and without side reactions: The entire process is a pure physical and chemical process with no corrosive products generated, and it does not cause any irreversible damage to well equipment and reservoir.

[0022] (3) Significant synergistic effect: Through synergistic effect, the viscosity reduction effect is far better than that of montmorillonite or ethanolamine alone, and the viscosity reduction rate of heavy oil at 90℃ can reach more than 50%.

[0023] (4) Green and low-cost raw materials: Natural montmorillonite is abundant and inexpensive (about RMB 200 / ton), while ethanolamine is a bulk chemical product (about RMB 8,000 / ton). The overall cost is only 1 / 100 of that of the traditional precious metal system.

[0024] (5) Good long-term stability: The dissociated heavy molecules are not easy to quickly re-aggregate, which can effectively reduce the lifting resistance of the wellbore and ensure stable production of the production well.

[0025] (6) Wide adaptability: It can be directly applied to heavy oil blocks with different physical properties and different salinity, without the need to modify existing oilfield wellbores and surface equipment, and the threshold for industrialization is extremely low. It is especially suitable for efficient viscosity reduction extraction of heavy oil in reservoir temperature (50~130℃) environment, providing technical support for low-cost development of medium and low temperature heavy oil reservoirs and marginal well recovery. Attached Figure Description

[0026] Figure 1 These are low-angle XRD patterns of intermediate and final products in the preparation process of the modified aluminum pillar montmorillonite used in the examples and comparative examples; Figure 2 These are Fourier transform infrared spectra of intermediate and final products in the preparation process of modified aluminum pillar montmorillonite used in the examples and comparative examples. Figure 3 These are XPS full-spectrum scans of the modified aluminum-pillared montmorillonite used in the examples and comparative examples; Figure 4 These are the O 1s high-resolution XPS spectra of the modified aluminum pillar-supported montmorillonite used in the examples and comparative examples; Figure 5 These are the Al 2p high-resolution XPS spectra of the modified aluminum pillared montmorillonite used in the examples and comparative examples; Figure 6 These are the Si 2p high-resolution XPS spectra of the modified aluminum pillar-supported montmorillonite used in the examples and comparative examples; Figure 7 These are nitrogen adsorption-desorption isotherms of intermediate and final products during the preparation of modified aluminum-pillared montmorillonite used in the examples and comparative examples. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. The following embodiments are only used to illustrate the technical solutions of the present invention and do not represent a limitation on the scope of protection of the present invention. All equivalent transformations based on the technical solutions of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, all raw materials used are common commercially available products.

[0028] The natural sodium-based montmorillonite used in the embodiments and comparative examples of this invention was purchased from Sinopharm Chemical Reagent Co., Ltd. It was an industrial-grade sodium-based ore with a cation exchange capacity (CEC) of 90 mmol / 100g and a fineness of 200 mesh, a common commercial raw material for montmorillonite catalytic materials in China. Aluminum trichloride hexahydrate (analytical grade) and sodium hydroxide (analytical grade) were both purchased from Sinopharm Chemical Reagent Co., Ltd. Ethanolamine: analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0029] The preparation methods of the modified aluminum-pillared montmorillonite used in the examples and comparative examples are as follows: (1) Preparation of aluminum hydroxyl oligomer pillar liquid Weigh out aluminum trichloride hexahydrate (AlCl3·6H2O) and dissolve it in deionized water to prepare a 0.2 mol / L aluminum salt solution. Place the aluminum salt solution in a constant temperature water bath and, under stirring conditions of 60℃ and 300 rpm, slowly add a 0.5 mol / L sodium hydroxide solution dropwise at a rate of 1~2 mL / min, controlling the OH content in the system. - With Al 3+ The molar ratio was 2.4:1; after the addition was completed, the mixture was kept at a constant temperature of 60°C and stirred for 24 hours to obtain a clear and transparent aluminum hydroxyl oligomer pillar liquid.

[0030] (2) Preparation of sodium-based montmorillonite suspension Natural sodium-based montmorillonite dry powder (SO) was dispersed in deionized water to prepare a 5% (w / w) montmorillonite suspension. The suspension was stirred and swollen at 60°C for 12 hours, and then ultrasonically dispersed at 300W for 30 minutes to fully peel and disperse the montmorillonite sheets, resulting in a uniform and stable suspension system.

[0031] (3) Cation exchange and pillaring reaction According to the feeding ratio of Al element to natural sodium-based montmorillonite dry powder of 0.8:100, the above-mentioned aluminum hydroxyl columnar liquid was slowly added dropwise to the montmorillonite suspension at a rate of 2~3 mL / min. The entire dropwise process was carried out at a constant temperature of 60℃ and stirred at 200 rpm. After the dropwise addition was completed, the reaction was continued at a constant temperature and stirred for 6 hours. Then the stirring was stopped and the mixture was allowed to stand at 60℃ for 12 hours to complete the exchange and columnarization process of aluminum hydroxyl ions on sodium ions in the montmorillonite interlayer.

[0032] (4) Post-processing and material finalization The resulting suspension was centrifuged at 8000 rpm, the supernatant was discarded, and the precipitate was repeatedly washed with deionized water until no Cl was detected in the supernatant using 0.1 mol / L silver nitrate solution. - The washed product was dried at 105℃ for 12h, ground to below 200 mesh (to obtain pillared intermediate S1), and then placed in a muffle furnace at a heating rate of 5℃ / min to 450℃, calcined at a constant temperature for 2h, and then naturally cooled to obtain modified aluminum pillared montmorillonite catalyst (S2).

[0033] The specific indicators tested were: aluminum loading 0.80wt%, interlayer spacing (d) 001 Crystal plane) 2.0 nm, specific surface area (BET method) 205 m² 2 / g.

[0034] Figure 1 The figures show the low-angle XRD patterns of intermediate products S0, S1, and the final product S2. The figures show that sodium-based montmorillonite S0 exhibits typical (001) crystal plane diffraction peaks, corresponding to the intrinsic interlayer spacing of natural montmorillonite. The diffraction peaks of the pillared intermediate S1, obtained through ion exchange, shift significantly to lower angles, indicating a substantial increase in interlayer spacing. This suggests that large-sized polymeric aluminum hydroxyl cations successfully entered the interlayer of montmorillonite through cation exchange, effectively opening up the silicon-oxygen layers. The interlayer spacing of the final calcined product S2 is 2.0 nm, slightly smaller than the intermediate but still much larger than the original. This is a normal phenomenon during calcination where polymeric aluminum hydroxyl decomposes into denser Al2O3 oxide pillars. It also indicates that the aluminum oxide pillars remain permanently in place as rigid supports within the interlayer, successfully constructing a stable pillared layered structure, and that the ordered layered structure of montmorillonite remained intact throughout the modification process.

[0035] Figure 2 The infrared spectra of intermediate products S0 and S1 and the final product S2 are shown. All three samples retain a wavelength of 1040 cm⁻¹. -1 The strong absorption peaks of the Si-O-Si framework at high frequencies and the vibrational peaks of the Si-O-Al framework in the low-frequency region indicate that neither the ion exchange nor the high-temperature calcination process destroyed the layered silica-oxygen framework of montmorillonite, and the matrix structure remained stable; meanwhile, at 3440 cm⁻¹... -1The interlayer water hydroxyl stretching vibration peak and 1630 cm -1 The water molecule bending vibration peak intensity showed a regular change with the modification process. The introduction of hydrated aluminum polycations in the S1 intermediate increased the degree of interlayer hydration. After high-temperature removal of free and coordinated water from the interlayer in the S2 calcined product, the water peak intensity decreased significantly, reaching 3620 cm⁻¹. -1 The presence of hydroxyl peaks in the skeletal framework throughout the entire structure further verifies the integrity of the clay octahedral framework.

[0036] Figures 3-6 The XPS spectrum of the modified aluminum-pillared montmorillonite product S2 shows that the main elemental composition of the product is Si, Al, and O, which matches the elemental composition of aluminum-pillared montmorillonite, proving that aluminum has been successfully introduced into the final product; the binding energy of the Al 2p high-resolution spectrum corresponds to six-coordinate Al. 3+ Furthermore, the peak position is biased towards the binding energy range of oxide aluminum, indicating that in addition to the skeletal aluminum of montmorillonite itself, there is also a large amount of pillar-introduced aluminum oxide. The O 1s high-resolution spectrum shows the superposition characteristics of Si-O bond oxygen in the montmorillonite skeletal framework and Al-O bond oxygen in the pillar-introduced aluminum oxide, which corroborates the successful introduction of aluminum oxide pillars between montmorillonite layers from the perspective of electrochemical environment.

[0037] Figure 7 The nitrogen adsorption-desorption isotherms for intermediate products S0 and S1, and the final product S2, show that all three samples exhibit type IV adsorption isotherms accompanied by type H3 hysteresis loops, typical characteristics of mesoporous materials. This corresponds to the slit-like mesoporous structure formed by the lamellar stacking of montmorillonite, indicating that the material retains its layered mesoporous properties after pillar modification. Simultaneously, the nitrogen saturation adsorption capacity shows a progressively increasing trend: S2 (calcined product) > S1 (pillar-supported intermediate) > S0 (sodium-based montmorillonite), corresponding to a progressively increasing specific surface area and pore volume. The specific surface area of ​​the final product (BET) reaches 205 m². 2 / g indicates that the aluminum pillars effectively opened up the interlayer space of montmorillonite, constructing more developed mesoporous channels. Furthermore, the oxide pillars were shaped after calcination, which further optimized the pore structure, directly demonstrating the success of the pillar modification.

[0038] Example 1 The composite viscosity reducer in this embodiment includes modified aluminum-pillared montmorillonite and ethanolamine, with a mass ratio of 1:2.

[0039] Oilfield 1's extra-heavy oil has a viscosity of 431082 mPa·s at 50℃ and an asphaltene content of 25.97 wt%. The above-mentioned viscosity reducer was used to perform low-temperature upgrading of the extra-heavy oil from Oilfield 1. Specific steps are as follows: (1) Take 70.0g of oilfield 1 extra-heavy oil and 30.0g of deionized water, add them to a 250mL sealed glass reaction vessel, and then add modified aluminum pillar montmorillonite and ethanolamine in a mass ratio of 1:2 and mix thoroughly. In the resulting mixture, based on the total liquid volume of the reaction system, the concentration of modified aluminum pillar montmorillonite is 1g / L and the concentration of ethanolamine is 2g / L.

[0040] (2) Place the reaction vessel on a magnetic stirring platform and react at 90°C and 200 rpm for 24 hours; (3) After the reaction is completed, cool to room temperature, transfer to a separation container, keep at 70°C for 2 hours, and then keep at room temperature for 24 hours to separate the oil and water phases and collect the upper layer of modified heavy oil.

[0041] The above experiments used a 7:3 oil-water mass ratio to simulate the actual state of coexistence of oil and water phases in the reservoir. A sealed glass reaction vessel with constant temperature stirring was used to simulate the formation temperature and fluid flow state in the pores, in order to verify the effect of viscosity reducer on the modification and viscosity reduction of the viscosity reducer under reservoir-like conditions.

[0042] The viscosity of the oil sample was determined using a rheometer with a plate module (Anton Parm MCR 302). Typically, 1 g of oil sample was uniformly coated onto the surface of the test plate. The test temperature was set between 50°C and 150°C, with a cooling rate of 1°C / s. The viscosity reduction rate was calculated according to equation (1). Where Δη is the viscosity reduction rate of the heavy oil, η0 is the initial viscosity of the crude oil, and η is the viscosity of the heavy oil after hydrothermal treatment.

[0043] ...Formula (1).

[0044] Test results: After upgrading, the viscosity of the extra-heavy oil from Oilfield 1 at 50℃ decreased to 215,000 mPa·s, with a viscosity reduction rate of approximately 50.1%.

[0045] Comparative Example 1 (Single modified aluminum column-supported montmorillonite) Only 1 g / L of modified aluminum-pillared montmorillonite was added, and the other conditions were the same as in Example 1.

[0046] Test results: viscosity reduction rate 22.0%; after standing for 3 days, the viscosity rebounded to 410,000 mPa·s, more than 95% of the original viscosity.

[0047] Comparative Example 2 (Monoethanolamine) Only 2 g / L ethanolamine was added, and the other conditions were the same as in Example 1.

[0048] Test results: viscosity reduction rate 18.0%; after standing for 2 days, the viscosity rebounded to 395,000 mPa·s, more than 92% of the original viscosity.

[0049] Parallel control experiments directly demonstrate the synergistic effect: Under the same reaction conditions of 90℃ and 24h, the viscosity reduction rate of single modified aluminum-pillared montmorillonite (1g / L) on extra-heavy oil in Oilfield 1 was 22.0%, and the viscosity reduction rate of single ethanolamine (2g / L) was 18.0%, with a theoretical sum of 40.0%; while the actual viscosity reduction rate of the composite viscosity reducer of this invention can reach 50.1%, which is significantly higher than the simple sum of the effects of the single components, proving that there is a clear synergistic promoting effect between the two.

[0050] This is because the viscosity-reducing composite agent provided by this invention has a deep synergistic effect. The Lewis acid sites on the surface of the modified aluminum-pillared montmorillonite can compensate for the limited depth of action of ethanolamine. Ethanolamine alone can only destroy the surface association structure of the asphaltene-colloid aggregate through hydrogen bonding, and cannot penetrate into the molecular interior to weaken the heteroatom bond forces. Therefore, the viscosity-reducing depth is limited and the viscosity rebounds quickly. The Lewis acid sites on the surface and in the interlayer of the modified aluminum-pillared montmorillonite can coordinate with the S and N heteroatoms of the CS and CN bonds in the heavy molecules that enter the interlayer, polarizing the heteroatom bonds and weakening the molecular cohesion, thus loosening the internal core structure of the aggregate at the microscopic level. This effect, together with the surface hydrogen bond dissociation of ethanolamine, forms an "inner-outer" synergy, achieving full-level depolymerization from the core to the surface of the aggregate, and the viscosity-reducing depth far exceeds that of a single component.

[0051] The viscosity-reducing composite agent provided by this invention has a long-lasting, stable, and synergistic effect. It can adsorb, anchor, and inhibit the secondary aggregation of heavy components, solving the problem of rapid rebound with single viscosity-reducing agents. After treatment with ethanolamine alone, the dissociated heavy molecules lose their external constraint and quickly reassociate, with viscosity typically rebounding significantly within 2-3 days. The layered structure and polar sites of the modified aluminum-pillared montmorillonite can adsorb and anchor the dissociated heavy small molecules, preventing them from recombining and agglomerating through steric hindrance. At the same time, ethanolamine molecules can bind between the heavy molecules and the montmorillonite surface, forming a stable adsorption solvation layer, further improving the system stability. The combination of the two achieves a closed loop of "depolymerization-anchoring-stabilization," meeting the time requirements for on-site gathering, transportation, and lifting.

[0052] Example 2 The composition of the composite viscosity reducer is the same as in Example 1; the experimental oil is heavy oil from Oilfield 2, with a viscosity of 4600 mPa·s at 50℃ and an asphaltene content of 2.49 wt%; the aqueous phase is seawater (mineralization 35000 mg / L), and the remaining steps are the same as in Example 1.

[0053] Test results: viscosity reduction rate 54.3%, and the heavy oil system was stable after standing for 7 days.

[0054] Example 3 The composition of the composite viscosity reducer is the same as in Example 1; the experimental oil is heavy oil from Oilfield 3, with a viscosity of 9297 mPa·s at 50℃ and an asphaltene content of 3.07 wt%; the aqueous phase is 20000 mg / L NaCl to simulate formation water, and the remaining steps are the same as in Example 1.

[0055] Test results: viscosity reduction rate 54.8%, and the heavy oil system remained stable after standing for 7 days.

[0056] Example 4 The composition of the composite viscosity reducer is the same as in Example 1; the experimental oil is extra-heavy oil from Oilfield 1; the aqueous phase is actual formation water from the oilfield (containing Ca). 2+ Mg 2+ (mineralization degree 20000 mg / L), the remaining steps are the same as in Example 1.

[0057] Test results: viscosity reduction rate 47.1%, and the heavy oil system was stable after standing for 7 days.

[0058] As can be seen from the above embodiments, the composite viscosity reducer of the present invention has a stable viscosity-reducing effect on heavy oil with different physical properties and different salinity, with significant synergistic effect, providing a low-cost technical solution for heavy oil extraction at reservoir temperatures.

[0059] The composite viscosity reducer of the present invention uses a fixed ratio of modified aluminum-pillared montmorillonite and ethanolamine to achieve effective viscosity reduction of heavy oil at reservoir temperatures. It is simple in composition, convenient in operation, environmentally friendly, and low in cost.

[0060] This composite viscosity reducer can be directly applied to on-site construction and wellbore lifting in various low-temperature heavy oil blocks on land and at sea. It is especially suitable for low-cost resumption of production in marginal heavy oil wells. No new large-scale equipment is required, and it can be rapidly scaled up and promoted. It has good industrial application value and promotion prospects.

Claims

1. An in-situ upgrading and catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures, characterized in that, The product comprises modified aluminum-pillared montmorillonite and ethanolamine; the mass ratio of modified aluminum-pillared montmorillonite to ethanolamine is 1:2; the modified aluminum-pillared montmorillonite is an inorganic pillar-modified product obtained by hydroxyl aluminum ion exchange and high-temperature calcination of natural sodium-based montmorillonite; wherein the aluminum loading in the modified aluminum-pillared montmorillonite is 0.8 wt%, the modified aluminum-pillared montmorillonite has a layered structure with an interlayer spacing of 1.8~2.2 nm and a specific surface area of ​​180~220 m². 2 / g.

2. The in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to claim 1, characterized in that, The particle size of the modified aluminum-pillared montmorillonite is less than 200 mesh.

3. The in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to claim 1, characterized in that, The steps of hydroxyaluminum ion exchange are as follows: (a) Add sodium hydroxide solution dropwise to an aluminum salt solution, OH - With Al 3+ The molar ratio is (2.0~2.8):1; after the addition is complete, continue aging for 12~36h to obtain a clear and transparent aluminum hydroxide oligomer pillar solution; (b) The hydroxyl aluminum oligomer pillar liquid was added dropwise to a sodium-based montmorillonite suspension with a mass ratio of Al element to natural sodium-based montmorillonite dry powder of (0.5~1.2):

100. After aging, the exchange and pillaring process of hydroxyl aluminum ions on sodium ions in the montmorillonite interlayer was completed.

4. The in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to claim 3, characterized in that, In step (a), both the dropping process and the aging process are carried out at 50~80℃ and 200~500rpm with a dropping rate of 1~2mL / min.

5. The in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to claim 3, characterized in that, In step (a), the concentration of the aluminum salt solution is 0.1~0.5 mol / L, and the concentration of the sodium hydroxide solution is 0.2~1 mol / L.

6. The in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to claim 3, characterized in that, In step (b), the sodium-based montmorillonite suspension is prepared by adding natural sodium-based montmorillonite to deionized water, stirring and swelling at 50-80℃ for 10-14 hours, and then ultrasonically dispersing at 200-500W power for 10-60 minutes to fully peel and disperse the montmorillonite sheets, thereby obtaining a uniform and stable sodium-based montmorillonite suspension.

7. The in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to claim 3, characterized in that, In step (b), the aluminum hydroxyl oligomer pillar solution is added dropwise to the montmorillonite suspension at a rate of 2-3 mL / min. The entire dropwise addition process is carried out at a constant temperature of 50-80℃ and stirred at 100-300 rpm. After the dropwise addition is completed, the reaction is continued at a constant temperature and stirred for 4-6 hours. Then, stirring is stopped, and the mixture is allowed to stand at 50-80℃ for 10-14 hours to complete the exchange and pillaring process of aluminum hydroxyl ions with sodium ions in the montmorillonite interlayer.

8. The application of the in-situ upgrading catalytic composite viscosity reducer for heavy oil extraction at reservoir temperatures according to any one of claims 1-7, characterized in that, At the reservoir temperature, the composite viscosity reducer is formulated into a working fluid and injected into the target oil layer. After the well is simmered for reaction, production is started.

Images