Nano-dispersion storage increasing agent for low-permeability water-sensitive oil reservoir and preparation method of nano-dispersion storage increasing agent

Abstract

The invention provides a low-permeability water-sensitive oil reservoir nano dispersion storage increasing agent and a preparation method thereof. The low-permeability water-sensitive oil reservoir nano dispersion storage increasing agent is prepared from enzyme, polysorbate, modified nano ZnO, span, modified nano SiO2, sodium hydroxide, absolute ethyl alcohol and water. The nano-dispersion storage increasing agent for the low-permeability water-sensitive oil reservoir is organically fused by enzyme, ester and a nanotechnology, not only improves the adsorption capacity of rock to crude oil from a stratum matrix, but also disperses oil and water into tiny liquid drops, improves the flowability of the oil and water in pores and throats and realizes water well injection increasing and oil well production increasing, and can be independently used during injection and use, but also can be independently used during injection and use. The product can also be matched with a nano pressure-reducing and storage-increasing agent for use; according to the invention, an oil layer microscopic seepage technology is applied, and enzyme, ester and nano materials are used for the first time to solve the problem of difficult seepage of micropores of the low-permeability water-sensitive oil reservoir from a stratum matrix.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a nano-dispersed storage enhancer for low-permeability water-sensitive oil reservoirs and a preparation method thereof. Background Art

[0002] Since low permeability water-sensitive reservoirs contain water-sensitive minerals or have small pores, when entering the water injection development period, clay absorbs water and expands, resulting in pore throat shrinkage, which results in water wells not being able to inject water or insufficient injection, oil wells not being able to produce oil, low production capacity, rapid energy decline, oil field production declining year by year, and oil production costs rising year by year. The main targeted production methods: water drive, active water drive, fracturing production, air drive, periodic well opening, etc., are limited by the cost of measures and the production increase cycle, and cannot meet the needs of efficient development of oil fields.

[0003] How to change the reservoir seepage conditions from the reservoir matrix, improve the reservoir permeability, improve the fluid fluidity, and make better use of the remaining oil is the key point of the present invention. The nano-dispersed reserve enhancer for low permeability water-sensitive reservoirs developed by us can effectively increase the oil control radius of the oil well, improve the reservoir permeation efficiency, improve the fluid state, and increase the oil field production capacity after being injected into the formation. The technical ideas are as follows:

[0004] First, according to the capillary seepage mechanics formula, it can be concluded that what needs to be done to reduce the capillary force is: reduce the interfacial tension between the two fluids, change the solid-liquid contact angle, and increase the capillary radius.

[0005] Capillary force formula p = 2σcosθ / r

[0006] Among them, P is the capillary force, σ is the interfacial tension between the two fluids, θ is the contact angle of the system, and r is the capillary radius.

[0007] (1) P is inversely proportional to the capillary radius r. The smaller r is, the larger P is.

[0008] (2) P is proportional to σ. The larger σ is, the larger P is.

[0009] (3) P is proportional to cosθ. When θ<90°, the capillary pores are hydrophilic, the capillary force P is positive, and the water surface rises spontaneously; when θ>90°, the capillary pores are lipophilic, the capillary force Pc is negative, and the water surface drops spontaneously.

[0010] Second, a large amount of research data proves that the order of three factors affecting the production capacity of throughput production and pressure drive is as follows: ability to change rock wettability > reducing oil-water interfacial tension > ability to emulsify and disperse crude oil.

[0011] Third, by reducing the water film thickness (increasing the capillary radius), the fluid seepage resistance can be greatly reduced.

[0012] Certain nanoparticles are adsorbed to form a nanofilm, which reduces the contact area between the water phase and the rock, and the thickness of the water film becomes thinner; zeta potential theory calculations found that after the nanoparticles are injected into the core, the action energy of the crude oil on the rock surface is reduced, and the crude oil is stripped off.

[0013] Fourth, improve the self-priming ability of the capillary and reduce the surface tension of the fluid.

[0014] Through the phenomenon of plant self-absorption of nutrient solution, we know that the self-absorption ability depends on the wettability of the solid and the surface tension of the liquid. The stronger the wettability of the solid (rock) surface, the greater the attraction to water; the smaller the surface tension of the liquid, the greater the relative attraction between the solid molecules and the inner side of the capillary object.

[0015] Based on the above ideas, the present invention provides a composite dispersed reserve-increasing treatment agent with enzyme ester nanoparticles as the core specifically for low permeability water-sensitive oil reservoirs; it can achieve "one dose with multiple functions and one dose with multiple uses", and is a disruptive product with great development potential - a nano-dispersed reserve-increasing agent for low permeability water-sensitive oil reservoirs. Summary of the invention

[0016] The purpose of the invention is to provide a nano-dispersed reserve enhancer for low-permeability water-sensitive oil reservoirs and a preparation method thereof. After the enzyme ester nano-emulsion enters the formation, its hydrophobic nano-scale particles can use their advantages to strongly adhere to the rock wall to peel off the water film. The enzyme and ester carried in the outer layer can change the crystal state of paraffin and effectively reduce the interaction between colloid and asphaltene molecules, break up large molecular clusters, disperse crude oil, present an oil-in-water state, improve the fluid flow capacity, and improve the ultimate recovery rate of the oil field.

[0017] A nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs, comprising enzyme, polysorbate, modified nano ZnO, Span, nano SiO 2 , sodium hydroxide, anhydrous ethanol and water.

[0018] Preferably, the nano-dispersed storage agent for low permeability water-sensitive oil reservoirs of the present invention comprises the following components by mass percentage: 30%-35% enzyme, 9%-12% polysorbate, 0.1%-0.5% modified nano ZnO, 0.6-1.2% Span, 0.2%-0.4% modified nano SiO 2 , 0.5%-1% sodium hydroxide, 1.5%-5% anhydrous ethanol, and the balance is water.

[0019] Preferably, the enzyme of the present invention is at least one of polyphenol oxidase, catalase and lipase, which can reduce the interaction between hydrocarbon, wax and colloid asphaltene molecules, break up molecular clusters and improve the fluidity of crude oil in pores and pore throats of low permeability water-sensitive reservoirs.

[0020] Preferably, the polysorbate is an organic substance with a chemical formula of C64 H 124 O 26 It is a non-ionic surfactant, at least one of polysorbate 21-81, and can be mixed with other surfactants. It has high stability, good water solubility, and is non-toxic and harmless.

[0021] Preferably, the Span is a compound having a chemical formula of C 24 H 44 O 6 It is a non-ionic surfactant, at least one of Span 60-85, can be mixed with other surfactants, has high stability, can be well dispersed in oil, paraffin and organic solvents, is dispersed in hot water, and is non-toxic and harmless.

[0022] Preferably, the modified nanomaterial is a modified hyperbranched nanomaterial that can smoothly enter the low permeability reservoir, including modified nano-SiO 2 Particles and modified nano ZnO particles, wherein the modified nano SiO 2 The particles are a kind of SiO 2 The modified nano ZnO material is a white hexagonal or spherical material with ZnO as the main component, and the particle size is 5-20nm. The modified nano ZnO particle is a white hexagonal or spherical particle with ZnO as the main component, and the average particle size is 50nm.

[0023] Preferably, the water is purified water that meets the specifications of national standard GB6682-2008.

[0024] The present invention also provides a method for preparing the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs, comprising the following steps:

[0025] Step (1) adding the formulated amount of enzyme and polysorbate into a large stirred reactor at room temperature, stirring and reacting at a speed of 120 rpm and 10-30° C. for 1-2 hours;

[0026] Step (2) Modified nano ZnO and modified nano SiO according to the formula amount 2 , sodium hydroxide, Span and anhydrous ethanol were placed in a small stirred reactor, and stirred at a constant temperature of 80°C and a speed of 2000 rpm for 10 minutes;

[0027] Step (3) The reactants in the small stirred reactor are quickly poured into the large stirred reactor, and the reaction is continued at a speed of 120 rpm and a constant temperature of 30° C. for 2 hours with uniform stirring. Water is added according to the formula amount and stirring is continued for 30 minutes. After that, heating is stopped and the mixture is cooled to room temperature to obtain a nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs.

[0028] Preferably, in step (1), the reaction time is 1 hour.

[0029] A method for using a nano-dispersed storage-increasing agent for low-permeability water-sensitive oil reservoirs, the method comprising injecting the nano-dispersed storage-increasing agent for low-permeability water-sensitive oil reservoirs and using the nano-pressure-reducing storage-increasing agent in combination, wherein the nano-pressure-reducing storage-increasing agent comprises an enzyme, nano-SiO 2 Any one or more of particles, polyethoxylated fatty alcohol, surface modifier S1-69 and water.

[0030] Preferably, the nano-dispersed reserve-enhancing agent and the nano-pressure-reducing reserve-enhancing agent for low permeability water-sensitive oil reservoirs are used in combination as follows: the nano-dispersed reserve-enhancing agent for low permeability water-sensitive oil reservoirs is first injected to decompose the crude oil near the wellbore, and then the nano-pressure-reducing reserve-enhancing agent is injected to remove blockages in the deep reservoir and increase reserves.

[0031] Preferably, the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs is suitable for low permeability water-sensitive oil reservoirs.

[0032] The innovative features of the present invention are:

[0033] The present invention uses oil layer microscopic seepage technology and takes the lead in using enzymes, esters and nanomaterials to solve the problem of micropore seepage in low permeability water-sensitive oil reservoirs from the formation matrix;

[0034] Modified nanoparticles, carrying OH-, can easily pin on the rock surface, reduce the water film thickness, and increase the pore throat radius. The enzymes and esters in the nano outer layer cause the underground fluid to change its flow state, thereby achieving the effect of increasing water well injection and oil well production.

[0035] The multi-property material fusion technology used in the present invention can form an emulsion with the multi-property materials fusion, which is heat-resistant, salt-resistant, large in quantity, wide in action area, and good in compatibility with oilfield water. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a composition diagram of the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs of the present invention;

[0037] Figure 2 This is a compatibility test diagram of the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula described in Example 2 in Experimental Example 1 of the present invention before entering the well;

[0038] Figure 3 This is a picture showing the effect of a rock permeability channel experiment under a microscope at 10,000 times magnification, of a low permeability water-sensitive reservoir nano-dispersed reserve enhancer prepared according to the formula described in Example 2 of the present invention at a constant crude oil temperature of 80°C and an agent concentration of 0.5%;

[0039] Figure 4 The interfacial tension of the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs prepared according to the formula described in Example 2 of the present invention was measured under the conditions of a constant crude oil temperature of 80° C. and an agent concentration of 0.3%;

[0040] Figure 5 The capillary self-imbibition height of the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula described in Example 2 of the present invention is measured under the conditions of a constant crude oil temperature of 80°C and an agent concentration of 0.3%;

[0041] Figure 6 The contact angle of the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula described in Example 2 of the present invention is measured under the conditions of a constant crude oil temperature of 80°C and an agent concentration of 0.3%;

[0042] Figure 7 This is a comparison chart of the experimental effect of crude oil fluidity before and after adding the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula described in Example 2 in Experimental Example 2 of the present invention;

[0043] Figure 8 This is a diagram showing the instantaneous water injection volume after the construction of the water well Y12-16 in the field application of the present invention;

[0044] Fig. 9 It is a graph showing the construction effect of oil well Q20-8 in the field application of the present invention. DETAILED DESCRIPTION

[0045] The following will be clearly and completely described in conjunction with the technical solutions in the embodiments of the invention. Obviously, the described embodiments are only part of the embodiments of the invention, not all of them. Based on the embodiments of the invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the invention.

[0046] It should be noted that the various technical terms mentioned in the present invention are technical terms that have long been clearly known in the relevant technical field, so no further explanation will be given.

[0047] Table 1 List of manufacturers purchasing raw materials of nano-dispersed storage enhancers for low permeability water-sensitive oil reservoirs

[0048]

[0049]

[0050] Example 1

[0051] The nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs described in Example 1 is composed of the following raw materials by mass percentage: 30% enzyme (the enzyme in this example is catalase), 9% polysorbate, 0.1% modified nano ZnO, 0.6% Span, 0.2% modified nano SiO 2, 0.5% sodium hydroxide, 1.5% anhydrous ethanol, and the remainder is pure water that meets the national standard GB6682-2008.

[0052] The preparation method of the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs comprises the following steps: (1) adding 30% catalase and 9% polysorbate to a large stirred reactor at room temperature, stirring and reacting uniformly at a speed of 120 rpm and 25° C. for 1 hour; (2) adding 0.1% modified nano-ZnO and 0.2% modified nano-SiO 2 , 0.5% sodium hydroxide and 1.5% anhydrous ethanol are placed in a small stirred reactor, and stirred for reaction at a constant temperature of 80°C and a speed of 2000 rpm for 10 minutes; (3) the reactants in the small stirred reactor are quickly poured into a large stirred reactor, and stirred for reaction at a speed of 120 rpm and a constant temperature of 30°C for another 2 hours, and the remaining amount of pure water that meets the specifications of the national standard GB6682-2008 is added, and the stirring is continued for 30 minutes, then the heating is stopped and the reaction is cooled to room temperature to obtain a low permeability water-sensitive reservoir nano-dispersed storage enhancer stock solution.

[0053] Example 2

[0054] The nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs described in Example 2 is composed of the following raw materials by mass percentage: 35% enzyme (the enzyme in this example is catalase), 12% polysorbate, 0.5% modified nano ZnO, 1.2% Span, 0.4% modified nano SiO 2 , 1% sodium hydroxide, 5% anhydrous ethanol, and the remainder is pure water that meets the national standard GB6682-2008.

[0055] The preparation steps of the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs described in Example 2 are the same as those in Example 1.

[0056] Comparative Example 1

[0057] The preparation method of the low permeability water-sensitive reservoir nano-dispersed storage agent described in this comparative example 1 is the same as that of Example 1, except that the raw material composition is different. No enzyme is added to the low permeability water-sensitive reservoir nano-dispersed storage agent described in this comparative example 1, and the raw materials are composed of the following raw materials by mass percentage: 9% polysorbate, 0.1% modified nano ZnO, 0.8% Span, 0.2% modified nano SiO 2 , 0.5% sodium hydroxide, 1.5% anhydrous ethanol, and the remainder is pure water that meets the national standard GB6682-2008.

[0058] Comparative Example 2

[0059] The preparation method of the nano-dispersed storage enhancer for low-permeability water-sensitive oil reservoirs described in this comparative example 2 is the same as that in Example 1, except that the raw material composition is different. No modified nanoparticles are added to the nano-dispersed storage enhancer for low-permeability water-sensitive oil reservoirs described in this comparative example 2. The nano-dispersed storage enhancer for low-permeability water-sensitive oil reservoirs described in this comparative example 2 is composed of the following raw materials, measured by mass percentage: 30% enzyme (the enzyme in this example is catalase), 9% polysorbate, 1.0% Span, 0.5% sodium hydroxide, 1.5% anhydrous ethanol, and the remainder is purified water that meets the specifications of the national standard GB6682-2008.

[0060] In order to avoid wasting manpower and material resources, it is necessary to conduct crude oil experiments to verify its feasibility, and determine the optimal formula and ratio before putting it into use in the well, as follows:

[0061] Experimental Example 1

[0062] Pre-well test: In Experimental Example 1, compatibility tests were conducted on the nano-dispersed storage enhancers for low permeability water-sensitive oil reservoirs described in the embodiment and the comparative example.

[0063] 500 ml of crude oil and free water (mineralization 185000 mg / L) contained in the crude oil were placed in 5 beakers respectively, and the beakers were placed in a constant temperature box at 50°C for 60 minutes. Then, a small amount of the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared in the two embodiments of the present invention and the three comparative examples was slowly poured into the crude oil. After slight stirring, the crude oil had good dispersion. After standing for 5 minutes, no precipitation was observed in the embodiments, and a small amount of precipitation was observed in the comparative examples, as shown in Table 2 for details.

[0064] The experimental results show that the use of multi-material fusion technology can combine the raw materials containing enzymes, polysorbate and modified nano-SiO 2 The low permeability water-sensitive reservoir nano-dispersed storage enhancer formed by the fusion of the multi-property materials of the particles has good compatibility with oilfield water and no precipitation. Among them, the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula described in Example 2 has the best compatibility effect. Figure 2 As shown ( Figure 2 The state of the crude oil after the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula of Example 2 is mixed with crude oil and stirred and then left to stand for 5 minutes) is shown.

[0065] Table 2 Compatibility test results

[0066] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Compatibility better good Difference Poor

[0067] Experimental Example 2

[0068] Test before entering the well: The compatibility experiment in Experimental Example 1 shows that the nano-dispersed reserve enhancer for low permeability water-sensitive reservoirs prepared according to the formula described in Example 2 has the best effect. The modified nanoparticles contained therein carry OH-, which can easily pin to the rock surface, peel off the water film, and increase the pore throat radius; and the enzymes and esters in the nano outer layer can decompose the crude oil into small droplets, making the crude oil more fluid, thereby achieving the effect of increasing water well injection and oil well production. We verified the ability of this agent to improve low permeability water-sensitive reservoirs and their oil and water flow conditions by testing the interfacial tension, capillary self-imbibition height, contact angle and other indicators of crude oil by adding nano-dispersed reserve enhancer for low permeability water-sensitive reservoirs. Figure 3 As shown, under a microscope of 10,000 times, the rock pore map before and after adding 0.5% concentration of nano-dispersed reserve enhancer for low permeability water-sensitive oil reservoirs shows that the nano-particles after adding the nano-dispersant are adsorbed and pinned on the rock to present a smooth surface distribution.

[0069] This experimental example 2 is used to evaluate the interfacial tension, capillary self-imbibition height, and contact angle. The main test is to determine the relationship between the interfacial tension, capillary self-imbibition height, and contact angle of the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared according to the formula described in Example 2 at different concentrations and temperatures, as follows:

[0070] 250 ml of crude oil was put into a beaker and placed in a thermostat at different temperatures for 60 minutes. Then, 0.3% of the low permeability water-sensitive reservoir nanodispersed storage enhancer was added. The interfacial tension, capillary self-imbibition height, and contact angle of the crude oil at different temperatures were measured. The interfacial tension, capillary self-imbibition height, and contact angle of the crude oil at different temperatures are shown in Table 3. Through this experimental example, it can be obtained that the interfacial tension of crude oil at a temperature of 60°C and above can reach 10 -2 mN / m, the capillary self-imbibition height is above 20mm, and the contact angle is <30°, which can improve the core from neutral wetness to strong water wetness. This shows that the nano-dispersed storage enhancer for low permeability water-sensitive reservoirs can strip the water film, increase the pore throat radius, decompose the fluid into small droplets, and solve the problem of micropore seepage in low permeability water-sensitive reservoirs from the formation matrix. It also reflects its characteristics of temperature resistance, salt resistance, large quantity, and wide effective area at low concentration.

[0071] Figure 4 , Figure 5 , Figure 6 The results show that after adding 0.3% of the low permeability water-sensitive reservoir nanodispersed storage enhancer prepared according to the formula described in Example 2 to crude oil at a constant temperature of 80°C, the interfacial tension, capillary self-imbibition height and contact angle were measured. Figure 4 is the measured interfacial tension, Figure 5 To measure the capillary self-priming height, Figure 6 The measured contact angle.

[0072] Table 3 Crude oil data at different temperatures

[0073] Temperature(℃) 90 80 70 60 Interfacial tension, mN / m 0.01 0.037 0.038 0.039 Capillary self-priming height (mm) 25 25 23 24 Contact angle° 26.69 25.6 25.55 24.6

[0074] (2) When the temperature is 60°C, 0.1%, 0.3%, and 0.5% of the low permeability water-sensitive reservoir nano-dispersed storage enhancer were added to the crude oil, and the interfacial tension, capillary self-imbibition height, and contact angle of the crude oil were measured at a temperature of 45-60°C, as shown in Table 4:

[0075] Through this experimental example, it can be seen that after adding 0.5% concentration of low permeability water-sensitive reservoir nano-dispersed storage enhancer, the interfacial tension, capillary self-imbibition height, and contact angle change effects are the best, and the fluidity of crude oil is the best; the fluidity effect is as follows Figure 7 As shown: the left side of the figure shows the fluidity state of crude oil, and the right side shows the fluidity state of crude oil after adding 0.5% concentration of low permeability water-sensitive reservoir nano-dispersed reserve-enhancing agent. It can be clearly seen that the low permeability water-sensitive reservoir nano-dispersed reserve-enhancing agent increases the fluidity of crude oil.

[0076] Table 4 Crude oil changes at different concentrations

[0077]

[0078] (3) According to the formulas of the embodiment and the comparative example, 0.5% concentration of the agent was prepared, and its effect was tested at 60°C, which reversely verified that the embodiment 2 of the present invention is indeed the optimal formula of the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs. See Table 5 for details.

[0079] Table 5 Test results of different agents at 0.5% concentration

[0080] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Temperature(℃) 60 60 60 60 Interfacial tension after adding the agent, mN / m 0.0098 0.0071 0.156 0.233 Capillary self-priming height, mm 26 28 15 18 Contact angle,° 27.22 28.9 26.22 35

[0081] After conducting laboratory experiments on nano-dispersed storage agents for low permeability water-sensitive reservoirs and verifying their interfacial tension, capillary self-imbibition height, and contact angle effects, they were put into use on site in the oil field. They were used in conjunction with nano-pressure-reducing storage agents in water injection wells to conduct pressure-reducing, injection-increasing, and storage-increasing tests. They were used alone in oil wells to conduct throughput tests.

[0082] The application cases of the technical solution of this application are as follows:

[0083] On-site well application case 1:

[0084] The nano-dispersed storage-increasing agent for low-permeability water-sensitive oil reservoirs prepared in Example 2 of the present invention, which has the best effect, was selected and combined with the nano-pressure-reducing storage-increasing agent and put into use on site.

[0085] Construction oil fields:

[0086] The Moriqing Oilfield in Yitong County, Jilin Province was selected. The regional structure is located in the southwest of the Moriqing fault depression in the Yitong Basin, with an oil-bearing area of ​​41.67km 2, geological reserves 2710.78×10 4 t / km 2 The main characteristics of the oil field are: poor reservoir properties, low porosity and low permeability, with an average porosity of 11.1% and an average permeability of 0.8×10 -3 μm 2 The average throat radius is 0.43-1.17μm; the clay mineral content is high, and it is highly water-sensitive and acid-sensitive; the crude oil has a high wax content, with an average wax content of 32.1%; the colloid content is 13.6%, the asphaltene content is 0.9%, and the freezing point is relatively high; during the development, as the water injection development begins, the pressure of the water injection wells continues to rise, the oil wells are ineffective, and the water injection and oil production development effects are affected.

[0087] The main problems faced are: more than 55% of the injection wells in the Moriqing Oilfield have injection pressures exceeding 25 MPa, and only 12% of the wells have injection pressures less than 20 MPa. The high injection pressure makes injection difficult, and the oil wells have long-term insufficient and ineffective fluid supply, which cannot meet the needs of rapid development.

[0088] Condition of the well before using the agent:

[0089] The water well layer data and water injection conditions before using the agent are shown in Tables 6 and 7. The original water injection pressure of wells 12-16 was 28 MPa, and the daily water injection volume was 20 cubic meters.

[0090] Table 6 Water well layer data before using the agent

[0091] Small layer number Perforation section (mm) Effective thickness (m) / number of layers Remark 1-2 2937.6-2968.5 9 / 5 Perforation only, no fracturing 3、6-8 2984.4-3120.1 17.6 / 5 Perforation Fracturing total 26.6 / 10

[0092] Table 7 Water injection before using the agent

[0093]

[0094] Construction method:

[0095] The segmented water injection method was adopted. The nano-dispersed storage-increasing agent (Agent) for low permeability water-sensitive oil reservoirs and the nano-pressure-reducing storage-increasing agent (B Agent) of the present invention were selected for use in the water injection well. The first and second segments were respectively subjected to pressure-reducing and plugging-removing injection. First, the nano-dispersed storage-increasing agent (Agent) for low permeability water-sensitive oil reservoirs was injected into the second layer through the oil pipe, and then the nano-pressure-reducing storage-increasing agent (B Agent) was injected through the oil pipe. Then, the A Agent and the B Agent were injected into the first layer through the casing. A total of 6.8 tons of agents were injected, as shown in Table 8:

[0096] Table 8 Construction status of Y12-16 well

[0097]

[0098] Comparison of water injection well effects before and after using the agent:

[0099] The Y12-16 well was put into normal water injection after construction on June 16, 2023. The nano-dispersed storage enhancer for low permeability water-sensitive reservoirs played a leading role in the water injection effect. The water injection volume was Figure 8 The field test water injection effect is shown in Table 9 below:

[0100] Table 9Y12-16 Water Well Injection Effect Table

[0101]

[0102] From Table 8, it can be concluded that before construction, the second layer had no water inflow at a pressure of 30 MPa, and the daily water injection was 0 cubic meters. After construction, the test stopped at a pressure of 25 MPa, and the hourly water injection volume could reach 4.74 cubic meters at a pressure of 26.5 MPa (see Figure 8 The high-pressure water meter value on the left) is converted into a daily water injection capacity of 113 cubic meters, and the water injection is stable; before construction, the pressure of layer 1 was 28MPa, with a daily water injection of 20 cubic meters. After construction, the stopping pressure was tested to be 25MPa. At a pressure of 27MPa, the water injection volume per hour can reach 4.47 cubic meters (see Figure 8 The high-pressure water meter value on the right) is converted into a daily water injection capacity of 107 cubic meters, and the water injection is stable.

[0103] The effectiveness of the oil wells after the construction reflects the synergistic effect of the combination of nano-dispersed reserve-increasing agent and nano-pressure-reducing reserve-increasing agent in increasing oil well production, as shown in Table 10:

[0104] The Y12-16 water well corresponds to a total of 5 oil wells. The oil well production from April to June 2023 before construction is compared with the production from July to December after construction. Before the 5 oil wells took effect, they produced 26.2 tons of liquid and 16.2 tons of oil per day. After the effect came out, they produced 33.4 tons of liquid and 22.3 tons of oil per day. The daily liquid production increased by 7.2 tons and the daily oil production increased by 6.1 tons. As of December 2023, the cumulative oil production increased by 375 tons.

[0105] Table 10Y12-16 well corresponding oil well effectiveness table

[0106]

[0107] It can be seen that the synergistic effect of the nano-dispersed reserve enhancer (Agent A) and the nano-pressure-reducing reserve enhancer (Agent B) for low permeability water-sensitive reservoirs is significant. When used in combination, the fluidity of crude oil is increased, the permeability of the formation is improved, the water injection pressure of the oil field is reduced, the water injection volume is increased, and the oil production is increased. The cumulative oil production increase is 375t, with significant economic benefits.

[0108] On-site well application case 2:

[0109] The nano-dispersed reserve-enhancing agent for low-permeability water-sensitive oil reservoirs prepared in Example 2 of the present invention with the best effect was selected for implementation in low-permeability water-sensitive oil reservoir wells, and the bio-nano pulse energy replenishment and reserve-enhancing technology was put into use on-site in low-permeability water-sensitive oil reservoir wells.

[0110] Construction oil fields:

[0111] The Changqing Jing'an Oilfield in Jingbian County, Shaanxi Province was selected. The regional structure is located in the central part of the Ordos Basin, with an oil-bearing area of ​​26.55km 2 , geological reserves of 785.6×10 4 t; The main characteristics of the oil field are: poor reservoir properties, low porosity and low permeability, with an average porosity of 9.8% and an average permeability of 1.67×10 -3 μm 2 The average throat radius is 0.52-1.23μm; the clay mineral content is high and it is highly water-sensitive; the average wax content of crude oil is 21%; the colloid asphaltene content is 12.1%, and the freezing point is 30℃; there is no corresponding water well in the development, and the oil wells rely on natural energy for exploitation, and the output declines rapidly, affecting the effect of oil production and development.

[0112] The main problems faced are: the well is located in an independent fault block, there are no corresponding water wells around it, the oil well has no energy replenishment, and the fluid supply is insufficient for a long time, which cannot meet the needs of rapid development.

[0113] Oil well condition before using the agent:

[0114] The oil well formation data before using the agent are shown in Table 11 and Table 12:

[0115] Table 11 Oil well formation data before using the agent

[0116] Small layer number Perforation section (mm) Effective thickness (m) / number of layers 2-3 1352.3-1359.6 4.4 / 2 5-6 1404.2-1411.8 4.0 / 2 total 8.4 / 4

[0117] Table 12 Oil recovery before using chemicals

[0118] Oil well number Production time Horizon Nissan oil t Nissan water t Water content% Cumulative oil production Q20-8 201707 2-6 1.1 5.5 82 1322

[0119] Construction method:

[0120] The nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs of the present invention was selected on the oil well, and the nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs was injected through the oil pipe. A total of 4 tons of the agent was injected, and the well was sealed for 15 days after the construction. See Table 13 for details:

[0121] Table 13Q20-8 Well Construction Status

[0122]

[0123] Comparison of oil well effects before and after using the agent:

[0124] The Q20-8 oil well was constructed in November 2023, using a nano-dispersed reservoir enhancer for low permeability water-sensitive reservoirs. The results after construction are as follows: Fig. 9 , as shown in Table 14:

[0125] Table 14Q20-8 Oil Well Results

[0126]

[0127] It can be concluded from Table 14 that before construction, the well produced 1.1 tons of oil and 5.5 tons of water per day, with a water content of 82%; after construction, the well produced a stable daily oil output of 10 tons, with a daily increase of 8.9 tons, and is currently continuing to be effective. Fig. 9 The graph shows the construction effect before and after the low permeability water-sensitive reservoir nano-dispersed storage enhancer prepared in Example 2 was added to the Q20-8 well in Jing'an Oilfield.

[0128] The effectiveness of the oil wells after construction reflects the effect of using nano-dispersed reserve enhancers in low permeability water-sensitive reservoirs in increasing oil well production.

[0129] It can be seen that the nano-dispersed reserve enhancer in low permeability water-sensitive reservoirs has a significant effect, increasing crude oil fluidity, improving formation permeability, and increasing oil field production, with a cumulative increase of 482 tons of oil, and significant economic benefits.

[0130] For those skilled in the art, the invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims. Any reference numerals in the claims should not be regarded as limiting the claims involved.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions and improvements made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the technical solution of the present invention.

Claims

1. A nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs, characterized in that: The composition comprises the following components by mass percentage: 30%-35% enzyme, 9%-12% polysorbate, 0.1%-0.5% modified nano ZnO, 0.6-1.2% Span, 0.2%-0.4% modified nano SiO2, 0.5%-1% sodium hydroxide, 1.5%-5% anhydrous ethanol, and the balance is water; The enzyme is at least one of polyphenol oxidase, catalase and lipase; The polysorbate is at least one of polysorbate 21-81; The Span is at least one of Span 60-85; The modified nano-SiO2 particles are amorphous white powder nano-materials modified with SiO2 as the main component, and the particle size is 5-20nm; The modified nano ZnO particles are white hexagonal or spherical particles with ZnO as the main component and an average particle size of 50 nm.

2. The nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs according to claim 1, characterized in that: The preparation method of the storage enhancing agent comprises the following steps: Step (1) adding the formulated amount of enzyme and polysorbate into a large stirred reactor at room temperature, stirring and reacting at a speed of 120 rpm and 10-30° C. for 1-2 hours; Step (2) Place modified nano ZnO, modified nano SiO2, sodium hydroxide, Span and anhydrous ethanol in a small stirred reactor according to the formula amount, and stir and react for 10 minutes at a constant temperature of 80° C. and a rotation speed of 2000 rpm; Step (3) The reactants in the small stirred reactor are quickly poured into the large stirred reactor, and the reaction is continued at a speed of 120 rpm and a constant temperature of 30° C. for 2 hours with uniform stirring. Water is added according to the formula amount and stirring is continued for 30 minutes. After that, heating is stopped and the mixture is cooled to room temperature to obtain a nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs.

3. The nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs according to claim 2, characterized in that: The reaction time in step (1) of the preparation method is 1 h.

4. A nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs according to any one of claims 1 to 3, characterized in that: The method for using the storage agent comprises: when injecting and using, the low permeability water-sensitive reservoir nano-dispersed storage agent and the nano-pressure-reducing storage agent are used in combination, wherein the nano-pressure-reducing storage agent comprises any one or more of enzyme, modified nano-SiO2 particles, polyethoxylated fatty alcohol, surface modifier S1-69 and water; The specific method of using the nano-dispersed reserve-enhancing agent for low permeability water-sensitive oil reservoirs and the nano-pressure-reducing reserve-enhancing agent in combination is: first inject the nano-dispersed reserve-enhancing agent for low permeability water-sensitive oil reservoirs to decompose the crude oil near the wellbore, and then inject the nano-pressure-reducing reserve-enhancing agent for deep plugging relief and injection.

5. The nano-dispersed storage enhancer for low permeability water-sensitive oil reservoirs according to claim 4, characterized in that: The nano-dispersed storage enhancer for low-permeability water-sensitive oil reservoirs is suitable for low-permeability water-sensitive oil reservoirs.

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