CN116606117A - A kind of degradable fly ash oil-water interface separator and its preparation method and application - Google Patents

Abstract

The invention discloses a degradable fly ash oil-water interface separator, a preparation method and application thereof. The separator is composed of the following raw materials in parts by weight: 10-20 parts of fly ash, 20-30 parts of polyaluminum chloride, 3-5 parts of urea, N,N-dimethylacrylamide/acryloylmorpholine binary 2-4 parts of polymer, 0.5-1 part of silica sol, the balance is water, and the sum of the parts by weight of the above components is 100. The water blocking system of the present invention is easy to prepare, has a wide source of raw materials, good injectability, simple construction technology, low cost, and can be automatically spread on the oil-water interface; before curing, it has high viscosity and anti-dilution, and has the advantages of "right-angle curing"; after curing, it is large The amplitude increases the compressive strength of the separator; at the same time, the separator has strong temperature and salt resistance, and the density of the separator is 1.05‑1.13g/ ^cm3 , which is adjustable and controllable, and can be degraded in a strong acid environment, which is conducive to protecting the formation environment.

Description

A kind of degradable fly ash oil-water interface separator and its preparation method and application

technical field

The invention relates to the technical field of oilfield chemistry, in particular to a degradable fly ash oil-water interface separator and a preparation method and application thereof.

Background technique

Dissolved cave reservoirs are widely distributed in the world. The heterogeneity of the reservoir is extremely strong, the oil-water occurrence state and connection relationship are complex, and the difficulty of water plugging technology is much higher than that of conventional sandstone reservoirs and other carbonate reservoirs. The artificial partition water blocking method may be the most effective water blocking method at present. The artificial partition built in the formation can be used to block the specific water outlet location.

At present, oilfield water shutoff agents are commonly used as polymer jelly, precipitation water shutoff agent and conventional cement. Polymer jelly will dissolve under high-temperature and high-salt formation conditions, and the solution viscosity is high, and the pumping resistance is large; the strength of the precipitation water shutoff agent is low; the conventional cement is easy to leak, and the water shutoff radius is small; so the conventional water shutoff The technology is not suitable for fracture-vuggy reservoirs with high temperature and high salinity.

CN202010997784.5 discloses a density-selective water plugging system for karst cave reservoirs. The component formula of the plugging agent system is calculated in parts by mass, including 50-75 parts of superabsorbent resin, 100-150 parts of ultrafine curable particles, 42-50 parts of micro-silicon, 5-10 parts of dispersant, 1-5 parts of retarder, 1000-1200 parts of formation water; superabsorbent resin is hydrophilic, lipophilic and water-absorbent resin whose volume expansion multiple is greater than a specific threshold; water plugging The overall density of the system is 1.05-1.14 g/cm ³ . The oil-water interface spreads in the cave, and then gradually solidifies, forming a partition at the oil-water interface, establishing a shield, adjusting the flow field, controlling the flow of the lower water body, and achieving the purpose of reducing water and increasing oil. The density of the system is adjustable, the compressive strength is moderate, and the water blocking effect is obvious. However, in a high-temperature and high-salt environment, the water blocking effect is significantly reduced, and it is not degradable. CN201210247170.0 discloses a density-selective water shutoff agent for carbonate rock oil wells. Its component formula is by weight, 100 parts of cement, 60-75 parts of fly ash, 50-58 parts of clay, 52-52 parts of micro silicon 62 parts, early strength agent 5-8 parts, fluid loss reducer 16-28 parts, water 1100-1200 parts. It stays between the oil-water interface and establishes a water blocking partition to ensure the curing effect. The plugging agent has strong compressive strength and obvious water blocking effect, but in the high temperature and high salt environment, the water blocking effect is obviously reduced, and it is not degradable. CN201610296608.2 discloses a polysaccharide polymer water blocking gel, which is composed of the following components in mass percentage: 2.5%-5% polysaccharide main agent, 1%-2% cross-linking agent, 1%-3% co-solvent, The gel-forming regulator is 0%-10%, the rest is water, and the sum of the components is 100%. The gel system has a wide range of temperature applications, and can be used for water shutoff operations in high-temperature reservoirs and low-temperature reservoirs; the final setting strength can reach level I of the visual code; it has good long-term stability; the gel system can be biologically degradation. However, the effect of this system decreases significantly in the environment of high salinity.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned technical deficiencies, propose a degradable fly ash oil-water interface separator and its preparation method and application, and solve the problems of high cost, low plugging strength and unsuitability for special water plugging systems in the prior art. High-temperature and high-salt oil reservoirs and non-degradable technical problems.

In the first aspect, the present invention provides a degradable fly ash oil-water interface separator. The degradable fly ash oil-water interface separator is composed of the following raw materials in parts by weight: 10-20 parts of fly ash, polychlorinated 20-30 parts of aluminum, 3-5 parts of urea, 2-4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, 0.5-1 part of silica sol, the balance is water, the above components The sum of the parts by weight is 100.

In a second aspect, the present invention provides a method for preparing a degradable fly ash oil-water interface separator, comprising the following steps:

Mix fly ash, polyaluminum chloride, urea, N,N-dimethylacrylamide/acryloylmorpholine binary polymer, silica sol and water, and then solidify to obtain a degradable fly ash oil-water interface barrier. plate.

In a third aspect, the present invention provides an application of a degradable fly ash oil-water interface separator, and the degradable fly ash oil-water interface separator is applied to oilfield water shutoff.

Compared with prior art, the beneficial effect of the present invention is:

Based on the electric double layer theory of solid-liquid interface diffusion, the present invention forms a water shutoff system suspended at the oil-water interface in combination with methods such as complexation to control ion balance; The process is simple and the cost is low. It can spread automatically at the oil-water interface, and then gradually solidify to form a partition at the oil-water interface; before curing, it has high viscosity and anti-dilution, and has the advantages of "right-angle curing"; after curing, the compressive strength is 1.2MPa-6.8 MPa, the maximum plugging pressure gradient can reach 86MPa/m, which greatly increases the compressive strength of the partition; at the same time, the partition has strong resistance to temperature and salt, with a temperature resistance of over 170°C and a salt resistance of over 250,000 mg/L. It has achieved a new breakthrough in the temperature and salt resistance of granular self-curing plugging agents; the density of the partition is 1.05-1.13g/cm ³ adjustable and controllable, and can be degraded in a strong acid environment, which is beneficial to the protection of the formation environment.

Description of drawings

Fig. 1 is the variation tendency of the quality of the degradable fly ash oil-water interface separator of the embodiment of the present invention 1-3 with temperature;

Fig. 2 is the variation trend of the quality of the degradable fly ash oil-water interface separator of the embodiment of the present invention 1-3 with the salinity;

Fig. 3 is the variation trend of the quality of the degradable fly ash oil-water interface separator of Example 1-3 of the present invention under strong acid high temperature conditions;

Fig. 4 is the stress-strain curve of the degradable fly ash oil-water interface separator of Example 2 and Comparative Examples 1-3 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In the first aspect, the present invention provides a degradable fly ash oil-water interface separator. The degradable fly ash oil-water interface separator is composed of the following raw materials in parts by weight: 10-20 parts of fly ash, polychlorinated 20-30 parts of aluminum, 3-5 parts of urea, 2-4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, 0.5-1 part of silica sol, the balance is water, the above components The sum of the parts by weight is 100.

In the present invention, fly ash is used as the main body, and urea and silica sol are used as the curing agent. Polyaluminum chloride and urea form a gel through hydration; fly ash is charged because it is a particle, and forms a stable skeleton material through hydrogen bonding; N,N-dimethylacrylamide/acryloylmorpholine The binary polymer has high-temperature thixotropy. After adding, the whole becomes a thixotropic skeleton material, which makes the separator have excellent salt resistance and temperature resistance, and is conducive to further improving the compressive strength of the separator; in addition, adding Silica sol has a strengthening effect, making the whole more stable. The present invention can realize the adjustable and controllable partition density of 1.05-1.13g/ ^cm3 through the selection of raw material ratio, which is beneficial to form the partition at the oil-water interface. Moreover, the inventors found during the experiment that before adding the N,N-dimethylacrylamide/acryloyl morpholine binary polymer, the mixed solution needs to be heated in an oven at 170°C for 4 hours to form a separator, and after curing, it is resistant to The maximum compressive strength is 5.5MPa; after adding the polymer, it only takes 3 hours to form the separator, and the maximum compressive strength of the separator is 6.8MPa. It can be seen that adding N,N-dimethylacrylamide/acryloylmorpholine binary polymer can also shorten the curing time and improve the curing effect.

In the present invention, the fly ash used is the main by-product of coal resource utilization, and the fly ash can be cleaned, cleaned and dried in sequence before use.

In this embodiment, the N,N-dimethylacrylamide/acryloyl morpholine binary polymer is obtained by mixing N,N-dimethylacrylamide and acryloyl morpholine and reacting under the action of an initiator . Among them, the mass ratio of N,N-dimethylacrylamide to acryloylmorpholine is 1:(0.5~2), further 1:1; the initiator is ammonium persulfate, and the amount of the initiator added accounts for 0.05%-0.1% by mass; the reaction temperature is 40-55°C, and the reaction time is 2-3h.

In this embodiment, the content of silicon dioxide in the silica sol is 20-40%, the degree of alkalization of polyaluminum chloride is 40-90%, and the content of alumina is 10-32%.

In some specific embodiments of the present invention, the degradable fly ash oil-water interface separator is composed of the following raw materials in parts by weight: 15 parts of fly ash, 25 parts of polyaluminum chloride, 4 parts of urea, N,N- 4 parts of dimethylacrylamide/acryloylmorpholine binary polymer, 0.5 part of silica sol, and water as the balance, and the total weight parts of the above components is 100.

In a second aspect, the present invention provides a method for preparing a degradable fly ash oil-water interface separator, comprising the following steps:

Mix fly ash, polyaluminum chloride, urea, N,N-dimethylacrylamide/acryloylmorpholine binary polymer, silica sol and water, and then solidify to obtain a degradable fly ash oil-water interface barrier. plate.

In this embodiment, the curing temperature is 150-200° C., further 170° C.; the curing time is 2-6 hours, further 3 hours.

In a third aspect, the present invention provides an application of a degradable fly ash oil-water interface separator, and the degradable fly ash oil-water interface separator is applied to oilfield water shutoff.

For avoiding repeating, in each following embodiment of the present invention, part raw material is summarized as follows:

Polyaluminum Chloride: High-purity polyaluminum chloride produced by Elfok, with a degree of alkalization of 90% and an alumina content of 30%;

Silica sol: Shandong Baite New Material Co., Ltd., with a silica content of 30%;

N,N-dimethylacrylamide/acryloylmorpholine binary polymer: mix N,N-dimethylacrylamide and acryloylmorpholine at a mass ratio of 1:1, and add 0.08% ammonium persulfate, stirred and heated to 50°C, reacted for 2 hours and then cooled.

Example 1

(1) According to 20 parts of fly ash, 30 parts of polyaluminum chloride, 4 parts of urea, 4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, 0.5 parts of silica sol, and the balance is Water, the sum of the parts by weight of the above-mentioned components is 100 and it is mixed;

(2) After fully dissolving, put the mixed solution into an oven at 170°C and heat for 3 hours to form a degradable fly ash oil-water interface separator.

Example 2

(1) According to 15 parts of fly ash, 25 parts of polyaluminum chloride, 4 parts of urea, 4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, 0.5 parts of silica sol, and the balance is Water, the sum of the parts by weight of the above-mentioned components is 100 and it is mixed;

(2) After fully dissolving, put the mixed solution into an oven at 170°C and heat for 3 hours to form a degradable fly ash oil-water interface separator.

Example 3

(1) According to 10 parts of fly ash, 20 parts of polyaluminium chloride, 4 parts of urea, 4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, 0.5 parts of silica sol, and the balance is Water, the sum of the parts by weight of the above-mentioned components is 100 and it is mixed;

(2) After fully dissolving, put the mixed solution into an oven at 170°C and heat for 3 hours to form a degradable fly ash oil-water interface separator.

Comparative example 1

(1) By 15 parts of fly ash, 25 parts of polyaluminum chloride, 4 parts of urea, 0.5 part of silica sol, the balance is water, and the sum of the weight parts of the above-mentioned components is 100 and it is mixed;

(2) After fully dissolving, put the mixed solution into an oven at 170°C and heat for 4 hours to form a degradable fly ash oil-water interface separator.

Comparative example 2

(1) According to 15 parts of fly ash, 25 parts of polyaluminum chloride, 4.5 parts of urea, 4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, and the balance is water, the above components The sum of the parts by weight is 100 and it is mixed;

(2) After fully dissolving, put the mixed solution into an oven at 170°C and heat for 3 hours to form a degradable fly ash oil-water interface separator.

Comparative example 3

(1) According to 15 parts of fly ash, 25 parts of polyaluminum chloride, 4 parts of N,N-dimethylacrylamide/acryloylmorpholine binary polymer, 4.5 parts of silica sol, and the balance is water, the above composition The sum of parts by weight is 100 and it is mixed;

(2) After fully dissolving, put the mixed solution into an oven at 170°C and heat for 3 hours to form a degradable fly ash oil-water interface separator.

Test group 1

Put the separators formed in the above-mentioned examples 1-3 into the drying oven at the temperature of 25°C, 50°C, 70°C, 90°C, 110°C, 130°C, 150°C, and 170°C for 24 hours, and measure the The quality of the separator is shown in Figure 1.

Please refer to Fig. 1, as can be seen from Fig. 1, the quality of the separator formed in Example 2 is moderate, and as the temperature increases, the quality of the separator formed in Examples 1-3 is basically unchanged, indicating that the oil-water provided by the present invention The interface separators all have good temperature resistance.

Test group 2

Put the separators formed in the above examples 1-3 into the aqueous solutions with salinity of 100,000mg/L, 150,000mg/L, 200,000mg/L, and 250,000mg/L respectively, and then put the whole into a 90°C drying oven After 12 hours, the final separator mass was measured, as shown in FIG. 2 .

Please refer to Fig. 2, as can be seen from Fig. 2, the partition quality that embodiment 2 forms is moderate, and along with the raising of salinity, the partition quality that embodiment 1-3 forms remains unchanged substantially, illustrates the present invention The oil-water interface separators provided have good salt resistance.

Test group 3

Mix the separators formed in the above examples 1-3 with a sufficient amount of conventional soil acid solution (3% HF + 12% HCl), heat in an oil bath at 110°C for 8 hours, and measure the final separator quality, as shown in the figure 3.

Please refer to Fig. 3. It can be seen from Fig. 3 that under the action of strong acid and high temperature environment, the separator formed in Example 1-3 is prone to degradation, which shows that the oil-water interface separator provided by the present invention can withstand strong acid under the formation environment. Under the action of all have significant degradation ability.

Test group 4

The separators formed in Example 2 and Comparative Examples 1-3 were respectively put into a compressive strength tester, and the stress-strain curve of the separator was recorded, as shown in FIG. 4 .

Please refer to Figure 4. It can be seen from Figure 4 that the compressive strength of the separators formed after omitting the binary copolymer (Comparative Example 1), omitting the silica sol (Comparative Example 2), and omitting urea (Comparative Example 3) respectively All have different degrees of reduction, indicating that in the system of the present invention, the binary copolymer, silica sol, and urea can exert their synergistic effect and significantly improve the compressive strength of the separator.

The specific embodiments of the present invention described above do not constitute a limitation to the protection scope of the present invention. Any other corresponding changes and modifications made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (10)

1. A degradable fly ash oil-water interface separator, characterized in that, the degradable fly ash oil-water interface separator is made up of the following raw materials in parts by weight: 10-20 parts of fly ash, polychlorinated 20-30 parts of aluminum, 3-5 parts of urea, 2-4 parts of N,N-dimethylacrylamide/acryloyl morpholine binary polymer, 0.5-1 part of silica sol, the balance is water, the above components The sum of the parts by weight is 100. 2. The degradable fly ash oil-water interface separator according to claim 1, characterized in that the content of silicon dioxide in the silica sol is 20-40%. 3. The degradable fly ash oil-water interface separator according to claim 1, characterized in that the polyaluminum chloride has an alkalization degree of 40-90% and an alumina content of 10-32%. 4. according to the described degradable fly ash oil-water interface separator of claim 1, it is characterized in that, described N,N-dimethylacrylamide/acryloyl morpholine binary polymer by N,N-di It is obtained by mixing methacrylamide and acryloylmorpholine and reacting under the action of an initiator. 5. The degradable fly ash oil-water interface separator according to claim 4, wherein the mass ratio of N,N-dimethylacrylamide to acryloylmorpholine is 1:(0.5～2) The initiator is ammonium persulfate, and the amount of the initiator added accounts for 0.05%-0.1% of the monomer mass; the reaction temperature is 40-55°C, and the reaction time is 2-3h. 6. The degradable fly ash oil-water interface separator according to claim 1, characterized in that, the degradable fly ash oil-water interface separator is made up of the following raw materials in parts by weight: 15 parts of fly ash, polymerization 25 parts of aluminum chloride, 4 parts of urea, 4 parts of N,N-dimethylacrylamide/acryloylmorpholine binary polymer, 0.5 part of silica sol, and the balance is water. The sum of the weight parts of the above components is 100. 7. a preparation method of degradable fly ash oil-water interface separator as described in any one of claim 1-6, it is characterized in that, comprises the following steps: Mix fly ash, polyaluminum chloride, urea, N,N-dimethylacrylamide/acryloylmorpholine binary polymer, silica sol and water, and then solidify to obtain a degradable fly ash oil-water interface barrier. plate. 8 . The method for preparing the degradable fly ash oil-water interface separator according to claim 7 , wherein the curing temperature is 150-200° C., and the curing time is 2-6 hours. 9 . The method for preparing the degradable fly ash oil-water interface separator according to claim 7 , wherein the curing temperature is 170° C., and the curing time is 3 hours. 10. An application of the degradable fly ash oil-water interface separator as described in any one of claims 1-6, characterized in that, the degradable fly ash oil-water interface separator is applied to oilfield water shutoff .