CN111892919A - A method of using hydrophobic metal-organic framework material to enhance oil displacement and profile control foaming - Google Patents

Abstract

The invention relates to a method for strengthening oil displacement, profile control and foaming by adopting a hydrophobic metal organic framework material, which comprises a direct liquid medium injection oil displacement method and a slurry-gas alternative oil displacement method. The direct liquid medium injection oil displacement method comprises the following steps: adding the hydrophobic metal organic framework material into the injected water, stirring to prepare hydrophobic metal organic framework material/water suspension slurry, and alternately injecting the suspension slurry slug and the single water slug to displace oil. The slurry-gas alternative oil displacement method comprises the following steps: adding the hydrophobic metal organic framework material into injected water or injected water-foaming agent mixed solution, stirring to prepare suspension slurry, and alternately injecting suspension slurry slug and gas slug to displace oil. The hydrophobic metal organic framework material is 2-methylimidazole zinc salt. The invention utilizes the hydrophobic metal organic framework material to give consideration to a plurality of effects of oil displacement, profile control, foaming, foam stabilization and the like, and has important significance for improving the crude oil recovery ratio of the oil reservoir with strong heterogeneity or cracks.

Description

A method of using hydrophobic metal-organic framework material to enhance oil displacement and profile control foaming

technical field

The invention belongs to the field of oil and gas development, and in particular relates to a method for enhancing oil displacement profile control and foaming by using a hydrophobic metal-organic framework material.

Background technique

Crude oil is mainly stored in the pores of the rock, and the recovery rate of conventional depressurization methods is not high. After depressurization development, further water flooding, gas flooding or chemical flooding can further improve the oil recovery. For reservoirs with strong homogeneity and fractures, the injection fluids channel faster with high-permeability channels, and the enhanced oil recovery is limited. At this time, it is necessary to change the fluid injection method or change the physical properties of the injected fluid, such as foam slug injection, gas-liquid injection Alternate injection, increase the viscosity of injected fluid, etc.

Metal-organic frameworks are porous materials synthesized from metal atoms and organic ligands under certain conditions. These materials have the advantages of adjustable structure and design, small particle size (nano-micron scale), and large specific surface area. They are suitable for gas storage and separation. It has a great potential for application (Park, K.S. et al. Exceptional chemical and thermalstability of zeolitic imidazolate frameworks. Proc. Natl Acad. Sci. USA, 2006, 103, 10186–10191). Due to the small opening diameter of the pores of some hydrophobic metal-organic framework materials, water molecules cannot enter the pores of the material, and can form a stable suspension slurry after mixing with an aqueous solution (ZL 201310014858.9, a separation method of ethane and ethylene in a mixed gas); The hydrophobicity of the material makes it have good affinity with hydrocarbon components, and can effectively adsorb hydrocarbon molecules (the main component of crude oil) in the water phase; in addition, since water molecules do not enter the pores of the material, when the gas dissolves When entering the slurry, part of the dissolved gas molecules in the slurry will be adsorbed by the metal-organic framework material, and the adsorbed gas molecules will reduce the interfacial tension between gas and water, so that the entire system exhibits good foaming and foam stabilization characteristics.

In view of the many characteristics exhibited by the hydrophobic metal-organic framework material, the present invention proposes a method for enhancing oil displacement profile control and foaming by using the hydrophobic metal-organic framework material. are all significant.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for enhancing oil displacement profile control and foaming by adopting hydrophobic metal organic framework material, comprising directly adding the hydrophobic metal organic framework material into water to form a slurry for oil displacement, or mixing the hydrophobic metal organic framework material with the starting material. The foaming agent is mixed and injected into the reservoir, and then gas is injected to realize foam flooding or foam profile control flooding. Utilizing the properties of some hydrophobic metal-organic framework materials, it can simultaneously take into account various effects such as oil displacement, profile control, foaming, and foam stabilization, which is of great significance for improving oil recovery in oil reservoirs with strong heterogeneity or fractures. It has a positive effect on expanding the application of metal organic framework materials.

In order to achieve the above technical purpose, the present invention adopts the following technical solutions.

Hydrophobic metal-organic framework materials will show a series of enhanced oil displacement effects after being added to the aqueous solution: one is to increase the viscosity of the injected water, reduce the water-oil mobility ratio of the aqueous solution flooding process, and delay the water breakthrough; the other is to suspend the hydrophobic metal in the water. The particles of organic framework materials have good lipophilicity, which can play an oil-washing effect; third, the particle size of metal organic framework materials is nano-scale, and it will stay in the reservoir rock where the throat is small to a certain extent. A blocking effect, thereby expanding the sweeping range of the aqueous solution and improving the sweeping efficiency of the displacement fluid; fourth, when the gas-water-metal organic framework materials are mixed, the whole system will produce foaming, especially when the gas-water-metal organic framework is mixed. When the framework material and the foaming agent are mixed, the hydrophobic metal-organic framework material can not only foam, but also has a high-efficiency foam stabilization effect, and the foam stabilization time can be increased by at least 2 times compared with no metal-organic framework material, showing excellent profile control. characteristic.

A method for enhancing oil displacement profile control and foaming by using hydrophobic metal-organic framework materials includes a direct injection liquid medium oil displacement method and a slurry-gas alternate oil displacement method.

The method of direct injection of liquid medium for oil displacement is as follows:

(1) adding the hydrophobic metal-organic framework material to the injected water, and stirring to prepare a hydrophobic metal-organic framework material/aqueous suspension slurry;

(2) According to the set ratio, the suspension slurry slug and the single water slug are alternately injected for oil displacement.

Described slurry-gas alternative oil displacement method, the process is as follows:

(1) adding the hydrophobic metal-organic framework material to the injection water or the injection water-foaming agent mixed solution, and stirring to prepare a suspension slurry;

(2) First inject a gas slug into the reservoir;

(3) The suspension slurry slug and the gas slug are alternately injected for oil displacement according to the set ratio.

Preferably, the injected water can be either formation water or laboratory prepared water, and the salinity of the prepared water is not lower than the salinity of the formation water.

Preferably, the diameter of the pores of the hydrophobic metal-organic framework material is not much different from the diameter of the water molecules. Thanks to the combined action of the material's hydrophobic properties and the diameter of the pores of the pores, it is difficult for water molecules to enter the pores of the material, and commercial metal-organic frameworks are preferred. Material 2-methylimidazole zinc salt (also known as: ZIF-8).

The hydrophobic metal-organic framework material ZIF-8 is a nano-microporous material (Pan Yong. Scale-up of ZIF-8 and ZIF-67) synthesized under suitable experimental conditions using ZnNO ₃ .6H ₂ O and 2-methylimidazole. Synthesis and Application in Separation of Gas/Liquid Mixtures. Doctoral Dissertation, China University of Petroleum (Beijing), 2016).

Preferably, the mass percentage of the hydrophobic metal organic framework material in the aqueous solution is 1-10%, preferably 1-5%.

Preferably, in the direct injection liquid medium flooding method, the volume ratio of the hydrophobic metal organic framework material/water suspension slurry slug to the single water slug is 1:3.

Preferably, in the slurry-gas alternative oil displacement method, the injected gas is a mixture of one or more of nitrogen, oxygen-depleted air, and natural gas without acid gas components.

Preferably, in the slurry-gas alternative oil displacement method, the foaming agent is a neutral or alkaline commercial foaming agent, preferably sodium dodecyl sulfate (SDS), with a mass fraction of 1%.

Preferably, in the slurry-gas alternative oil displacement method, the gas slug is larger than the slurry slug, and the volume ratio of the suspended slurry slug to the gas slug is preferably 1:3.

Preferably, for oil reservoirs with strong intra-layer heterogeneity, alternate injection of suspended slurry slug and single water slug is used for oil displacement, and for oil reservoirs with strong inter-layer heterogeneity or fractures, the choice of Suspension slurry slug-gas slug are alternately injected for oil displacement.

The technical principle of the present invention is as follows:

The hydrophobic metal-organic framework material ZIF-8 is a microporous material synthesized by ZnNO ₃ .6H ₂ O and 2-methylimidazole under suitable experimental conditions. The lattices are connected by a hexagonal window with a diameter of 0.34 nm, which is connected by Zn ²⁺ and 2-methylimidazole ligands and a quadrilateral window with a smaller diameter. Since the diameter of the quadrilateral window is much smaller than that of common gas molecules, so The adsorbed medium (gas) must pass through the hexagonal window formed by Zn ²⁺ and 2-methylimidazole ligands to enter the ZIF-8 pores. Although the hexagonal window diameter (0.34 nm) on ZIF-8 is slightly larger than that of water molecular dynamics (∼0.29 nm), the presence of _-CH3 groups on the organic ligand 2-methylimidazole makes ZIF-8 It has extremely strong hydrophobic properties, making it difficult for water molecules to enter the ZIF-8 pores (Huang Liu, et al. Tunable integration of absorption membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature. Scientific Reports, 2016, 6, 21114).

Compared with the prior art, the metal-organic framework material used in the present invention has high temperature resistance and good suspension stability in an aqueous solution. Utilizing the hydrophobic, lipophilic, nano-micro-scale, adsorbed gas foaming and foam-stabilizing properties of metal-organic framework materials, the traditional oil displacement process can simply reduce the fluidity of injected fluid, provide oil washing efficiency, profile control, foaming, Enhanced foam stability and other mechanisms are coupled to significantly improve oil recovery and have broad application prospects.

Description of drawings

Figure 1 is a comparison diagram of the oil displacement effects of formation water and ZIF-8 slurry in Example 1.

FIG. 2 is a comparison diagram of the alternate flooding effect of the combination of nitrogen and SDS aqueous solution, and the alternate flooding of nitrogen and ZIF-8/formation water-SDS slurry combination in Example 2.

Detailed ways

The present invention is further described below according to the accompanying drawings and examples, so as to facilitate the understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, they are protected within the scope of the present invention. List.

In the present invention, the hydrophobic metal organic framework material and the foaming agent are all selected from existing commercial products. The hydrophobic metal-organic framework material such as ZIF-8 was purchased from Sigma China official website (Item No.: 691348), and the foaming agent was purchased from Aladdin Chemical Reagent Network. Among them, the experimental evaluation of the effect of hydrophobic metal organic framework materials for oil displacement mainly includes the following indicators: First, compared with single injection of water, using the hydrophobic and lipophilic properties of hydrophobic metal organic framework materials, the injection of hydrophobic metal organic framework materials/water slurry improves crude oil. The degree of recovery; second, compared with adding only a single foaming agent solution, adding hydrophobic metal-organic framework material increases the foaming volume of the solution and prolongs the foam stabilization time; the third is compared with only gas injection and single foaming agent solution. , further enhanced oil recovery after gas injection and hydrophobic metal organic framework material/foaming agent slurry.

Example 1

A method of using hydrophobic metal-organic framework material to enhance oil displacement and profile control and foaming adopts direct liquid injection medium flooding. Formation water was prepared in the laboratory, and ZIF-8/formation water slurry was prepared according to the mass ratio of ZIF-8:formation water 2:98; high-permeability cores (permeability 125mD, plug sample) and low-permeability cores (permeability) were selected. The formation oil (bubble point 7.6MPa, density: 0.7663g/cm) was prepared by saturating both cores at a reservoir temperature of 78℃ and a pressure of 32MPa. ³ ). First, a single formation water was used to replace oil until both the high-permeability core and the low-permeability core produced no oil, and the crude oil recovery ratios of the high-permeability and low-permeability cores were measured to be 35.8% and 26.2%, respectively (Fig. 1). 8/Formation water slurry: The formation water volume ratio is 1:3 alternately injected into the displacement system to displace the remaining crude oil in the core, and the slug size is 0.05 times the total pore volume of the two cores; The pressure difference at both ends of the seepage core gradually increased, and oil was recovered from the high-permeability core after alternately injecting two slurry slugs, indicating that the slurry played an oil-washing effect; after alternately injecting three slurry slugs, the high-permeability core no longer produced liquid , indicating that the ZIF-8 particles blocked the pores in the high-permeability core, the liquid output of the low-permeability core increased, and oil began to be produced. After the liquid medium was injected with 1.5 times the total pore volume of the two cores, the port of the low-permeability core no longer produced oil. Finally, the crude oil recovery factors of the high and low permeability pipes were measured to be 52.4% and 48.5% respectively (see Figure 1), and the crude oil recovery factors were significantly improved. It shows that the ZIF-8 material has the effect of washing oil and plugging high-permeability pore channels and profile control in the whole displacement process at the same time.

Example 2

A method of using hydrophobic metal-organic framework material to strengthen oil displacement profile control and foaming adopts alternate displacement of gas and hydrophobic metal-organic framework material slurry. ZIF-8/formation water-SDS slurry was prepared according to the mass ratio of ZIF-8:formation water:sodium dodecyl sulfate (SDS) of 2:97:1. Select high-permeability cores (permeability 125mD, plunger sample) and low-permeability cores (permeability 33mD, plunger sample) into the high-low-permeability parallel displacement system, and let the two reservoirs run at a reservoir temperature of 78°C and a pressure of 32MPa. The formation crude oil prepared by the block cores is saturated (bubble point 7.6MPa, density: 0.7663g/cm ³ ). First inject a nitrogen slug with 0.1 times the total pore volume of the two cores, and then maintain the slurry slug: the nitrogen slug is equal to 1:3, and the crude oil in the cores is driven by gas-slurry alternately until no oil is produced. During the alternate flooding process, the size of the fluid slug is 0.05 times the total pore volume of the two cores. Finally, the oil recovery factors of high permeability core and low permeability core are 67.3% and 60.6%, respectively (see Fig. 2).

For comparative analysis, a solution was prepared according to the mass ratio of formation water:sodium dodecyl sulfate (SDS) to 99:1, and the experiment was repeated once with SDS aqueous solution instead of ZIF-8/formation water-SDS slurry, and finally a hypertonic core was obtained. and low-permeability cores are 59.8% and 51.2%, respectively (see Fig. 2), which are significantly lower than the alternate flooding effect of nitrogen and ZIF-8/formation water-SDS slurry. The displacement process plays a significant role in enhancing oil recovery.

Example 3

For the evaluation of the foaming and foam stabilization effects of ZIF-8 in Example 2: 10 mL of SDS-formation aqueous solution (the mass fraction of SDS is 1 wt %) and high-pressure nitrogen gas (pressure of 32 MPa) are mixed in a high-pressure device with a visual window, The water-gas volume ratio was 1:5, and the experimental temperature was the reservoir temperature of 78 °C. It was found that the volume of bubbles generated was 18.5 mL, but the bubbles basically disappeared after standing for 20 minutes (see Table 1).

Then 10 mL of ZIF-8/formation water-SDS slurry (the mass fraction of ZIF-8 is 2wt% and the mass fraction of SDS is 1wt%) and high pressure nitrogen gas (pressure is 32MPa) are mixed in a high pressure device with a visual window , the volume ratio of slurry to gas was also 1:5, the experimental temperature was the reservoir temperature of 78 °C, and it was found that the final volume of bubbles produced was 27 mL, indicating that the ZIF-8 material participated in and promoted the foaming; and after standing for 120 minutes The bubble volume is still 26 mL (see Table 1), which proves that the ZIF-8 material has an excellent bubble stabilization effect.

Table 1 ZIF-8 strengthens foaming and foam stabilization effect data

Claims (11)

1. A method for enhancing oil displacement profile control and foaming by adopting hydrophobic metal organic framework materials, including direct injection liquid medium oil displacement method and slurry-gas alternate oil displacement method. 2. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming as claimed in claim 1, it is characterized in that, described direct injection liquid medium oil displacement method, process is as follows: (1) Add the hydrophobic metal-organic framework material to the injected water, and stir to prepare a hydrophobic metal-organic framework material/water suspension slurry; (2) According to the set ratio, the suspension slurry slug and the single water slug are alternately injected for oil displacement. 3. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming as claimed in claim 1, it is characterized in that, described slurry-gas alternate oil displacement method, process is as follows: Add the hydrophobic metal-organic framework material to the injection water or the injection water-foaming agent mixture, and stir to prepare a suspension slurry; (2) First inject a gas slug into the reservoir; (3) The suspension slurry slug and the gas slug are alternately injected for oil displacement according to the set ratio. 4. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming as claimed in claim 2 or 3, it is characterized in that, described injection water is formation water or laboratory preparation water, and the mineral water of preparation water. The degree of salinity is not lower than the salinity of formation water. 5. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming as claimed in claim 2 or 3, it is characterized in that, described hydrophobic metal organic framework material is 2-methylimidazole zinc salt, adopts Nano-microporous materials synthesized by ZnNO ₃ .6H ₂ O and 2-methylimidazole. 6. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming method as claimed in claim 2 or 3, it is characterized in that, the mass percent of described hydrophobic metal organic framework material in aqueous solution is 1-10 %. 7. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming method as claimed in claim 2, it is characterized in that, in direct injection liquid medium oil displacement method, hydrophobic metal organic framework material/water suspension slurry section The volume ratio of plug to single water slug is 1:3. 8. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming method as claimed in claim 3, it is characterized in that, in slurry-gas alternate oil displacement method, injected gas is nitrogen, deoxidized air, non-volatile One or more blends of natural gas containing acid gas components. 9. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming method as claimed in claim 3, it is characterized in that, in slurry-gas alternative oil displacement method, foaming agent is sodium lauryl sulfate , the quality score is 1%. 10. A method for enhancing oil displacement profile control and foaming using hydrophobic metal organic framework material as claimed in claim 3, wherein in the slurry-gas alternate oil displacement method, the volume of the slurry slug and the gas slug is suspended. The ratio is 1:3. 11. a kind of method that adopts hydrophobic metal organic framework material to strengthen oil displacement profile control foaming method as claimed in claim 2 or 3, it is characterized in that, for the oil reservoir with stronger heterogeneity in the layer, select to use suspension slurry Alternate injection of slug-single water slug for oil displacement. For oil reservoirs with strong interlayer heterogeneity or fractures, alternate injection of suspension slurry slug-gas slug is selected for oil displacement.

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