Silicate hardened plugging system and preparation method and application thereof

Abstract

The invention discloses a silicate hardened plugging system as well as a preparation method and application thereof. A mixture of phenols and aldehydes or a phenolic resin prepolymer or phenolic resin forms an integral skeleton structure, silicate and an activating agent form silicic acid gel, and then a pH regulator and a hardening retarder are supplemented, so that the curing agent can be hardened in a temperature range of 60-150 DEG C, and a formed solidified body is high in compressive strength and has strong temperature resistance, aging resistance and scouring resistance.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, and in particular to a silicate hardening plugging system and a preparation method and application thereof. Background Art

[0002] During the development of oil fields, the heterogeneity of the reservoir itself and the imbalance within the oil-water well group will cause the injected water to rush and flow into the oil well along the high permeability zone, resulting in high water content in the oil well and a significant decline in economic benefits. The plugging technology aims to plug the high permeability layer, increase the sweep coefficient of the injected water, or improve the liquid production profile. Currently, water-soluble polymer gel, pre-crosslinked gel particles, polymer microspheres and water glass plugging agents are mainly used.

[0003] The water-soluble polymer gel system has poor temperature and salt resistance, and its application in high-temperature and high-salinity oil reservoirs is limited. Pre-crosslinked gel particles and polymer microspheres are particularly suitable for profile control. When used for oil well water plugging, the plugging strength is low and the effective period is short. Water glass plugging agents are mainly used for water well profile control and thermal oil well water plugging due to their low cost and good temperature resistance.

[0004] CN106634908 A discloses a high temperature resistant interpenetrating network composite gel profile control agent, which is composed of water glass, crosslinking agent I (which is a hydrolyzable ester compound), crosslinking agent II (which is selected from phenolic resin crosslinking agent, chromium lactate, aluminum citrate or zirconium citrate compound), polymer (which is selected from hydrolyzable polyacrylamide, xanthan gum or cellulose), auxiliary agent I (which is selected from sodium bentonite, calcium bentonite or nano-silicon dioxide), auxiliary agent II (which is selected from diatomaceous earth or silicate soil) and water. CN102516961 A provides an organic / inorganic crosslinking system plugging agent suitable for high temperature oil reservoirs, which is composed of an organic crosslinking agent, water glass, a stabilizer (non-ionic polyacrylamide) and water. CN104479652A discloses a water glass profile control agent and a preparation method thereof, wherein a nonionic unsaturated monomer is reacted with a large amount of inorganic fillers and inorganic silicates with expansion performance and cross-linking effect under the action of a cross-linking agent to obtain the obtained product, and the system consists of nonionic unsaturated monomers, water glass, inorganic fillers, cross-linking agents, oxidants, reducing agents, and deblocking agents. CN103627376 B discloses a water glass inorganic gel plugging agent and a preparation and use method thereof, wherein the product has a component ratio of 10-40% water glass, 0.1-0.3% polyacrylamide, 0.1-0.2% sodium dodecylbenzene sulfonate, 0.1-0.3% aluminum dihydrogen phosphate, 1-6% N,N-dimethylformamide, and the rest is water.

[0005] The invention patent with the publication number CN112852393B provides a high-temperature resistant plugging agent for heavy oil horizontal wells and a water plugging method, which consists of sodium silicate, urea, and a filler. At the same time, this patent introduces a water plugging method, that is, using the above high-temperature resistant plugging agent as the near-well slug and nitrogen foam gel plugging agent as the far-well slug, and using the synergistic cooperation between the two plugging agents to ensure the water plugging effect of the horizontal well.

[0006] The invention patent with the publication number CN1268713 C provides a sodium silicate high-temperature resistant plugging agent for oil production. This plugging agent contains sodium silicate, a cross-linking agent, and water. The applicable temperature range of this plugging agent is wide, and it can be cured within the temperature range of 60 - 280 °C. After curing, it has high strength, the overall compressive strength is between 0.2 - 0.5 MPa, and it has good long-term thermal stability. It is applicable to steam drive or steam soak oil wells to prevent steam channeling.

[0007] The invention patent with the publication number CN112143477 B discloses a silicate plugging agent system and its application method. This silicate plugging agent system includes an initiator (CO 2 ), and an aqueous chemical agent solution (2 - 16 wt% of silicate, 0.005 - 0.3 wt% of water-soluble polymer, 0.02 - 0.5 wt% of rubber particles, and the balance is water).

[0008] The invention patent application with the publication number CN153259A discloses an inorganic delayed silicate gel plugging agent. This plugging agent system uses sodium silicate as the main component and adds at least one of ethyl acetate, acetamide, and ethanol as a delayed activator to form a gel at 70 - 110 °C.

[0009] In the above-mentioned prior art, silicate is used as a plugging agent mainly with silicate and an activator as the main agents, supplemented by polymers and cross-linking agents or composite components that can form cross-linked polymers, and finally form a plugging substance with gel-like properties. The defects of this type of plugging substance are limited plugging strength and poor erosion resistance. Summary of the Invention

[0010] In view of the above deficiencies in the prior art, the present invention provides a silicate hardening type plugging system to overcome the disadvantages of weak plugging strength and poor erosion resistance of the current silicate gel plugging agent. The technical route adopted to achieve its purpose is to form an overall framework structure with a mixture of phenol and aldehyde or a phenolic resin prepolymer or phenolic resin, form a silicate gel with silicate and an activator, and then supplement with a pH regulator and a hardening retarder. It can be hardened within the temperature range of 60 - 150 °C, and the formed consolidated body has high compressive strength and strong temperature resistance, anti-aging, and anti-erosion capabilities.

[0011] To achieve the above purpose, on the one hand, the present invention discloses a silicate hardening type plugging system, and the mass percentages of each component are as follows:

[0012] 10% to 30% silicate, 0.5 to 5% activator, 0.5 to 10% precursor of the overall framework structure, 0 to 1% hardening retarder, pH regulator is 0.5% to 0.8%, the balance is water, and the total composition is 100%.

[0013] Preferably, the silicate is one or a mixture of several of sodium silicate, potassium silicate, and lithium silicate.

[0014] Preferably, the activator is one of urea, methyl acetate, and N,N-dimethylformamide.

[0015] Preferably, the precursor of the overall framework structure is water-soluble phenolic resin or its prepolymer or monomer, forming a framework structure throughout the silica gel.

[0016] Preferably, the hardening retarder is one of sodium hexametaphosphate or nanocellulose.

[0017] Preferably, the pH regulator is one of sodium hydroxide or sodium bicarbonate.

[0018] The second aspect of the present invention provides a preparation method of a silicate hardening type plugging system, and the specific preparation steps are as follows:

[0019] (1) Weigh various raw materials according to the ratio, add water and silicate into a preparation device and stir.

[0020] (2) Then successively add the activator, the hardening retarder, and the pH regulator, continue to stir, add the precursor of the overall framework structure while stirring, and continue to stir after adding to obtain the reaction liquid of the system.

[0021] (3) Conduct a hardening reaction to obtain the silicate hardening type plugging system.

[0022] Preferably, the specific preparation steps are as follows:

[0023] (1) Weigh various raw materials according to the ratio, add water and silicate into a preparation device, and stir on a magnetic stirrer at a stirring speed of 200 - 300 r / min for 0.5 - 1 hour.

[0024] (2) Then successively add the activator, the hardening retarder, and the pH regulator, continue to stir for 0.5 - 1 hour, add the precursor of the overall framework structure while stirring, and continue to stir for 0.5 - 1 hour after adding to obtain the reaction liquid of the system.

[0025] (3) Conduct a hardening reaction at a temperature of 60 - 150 °C to obtain the silicate hardening type plugging system.

[0026] The third aspect of the present invention provides an application of a silicate hardening type plugging system in oil production.

[0027] The application of the silicate hardening type plugging system as a profile control agent for water injection wells, a water shutoff agent for oil wells, or a sealing agent for high water cut formations in oil production.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] The present invention forms an overall framework structure with a mixture of phenols and aldehydes, or a phenolic resin prepolymer, or a phenolic resin. A silica gel is formed with silicate and an activator, and is supplemented with a pH regulator and a hardening retarder. It can be hardened within the temperature range of 60 to 150 °C. The formed consolidated body has high compressive strength and strong resistance to temperature, anti-aging and anti-scouring capabilities. Specific Embodiments

[0030] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0031] On the one hand, the present invention discloses a silicate hardening type plugging system, and the mass percentages of each component composition are as follows:

[0032] 10% - 30% of silicate, 0.5 - 5% of activator, 0.5 - 10% of the precursor of the overall framework structure, 0 - 1% of hardening retarder, the pH regulator is 0.5% - 0.8%, and the balance is water, and the total composition is 100%.

[0033] Preferably, the silicate is one or a mixture of sodium silicate, potassium silicate, and lithium silicate.

[0034] Preferably, the activator is one of urea, methyl acetate, and N, N-dimethylformamide.

[0035] Preferably, the precursor of the overall framework structure is a water-soluble phenolic resin or its prepolymer or monomer, forming a framework structure throughout the silica gel.

[0036] Preferably, the hardening retarder is one of sodium hexametaphosphate or nanocellulose.

[0037] Preferably, the pH regulator is one of sodium hydroxide or sodium bicarbonate.

[0038] The second aspect of the present invention provides a preparation method of a silicate hardening type plugging system, and the specific preparation steps are as follows:

[0039] (1) Weigh various raw materials according to the ratio, add water and silicate into a preparation device and stir;

[0040] (2) Then successively add an activator, a hardening retarder, and a pH regulator, continue to stir, and add the precursor of the overall framework structure while stirring. After adding, continue to stir to obtain the reaction liquid of this system;

[0041] (3) Conduct a hardening reaction to obtain this silicate hardening type plugging system.

[0042] Preferably, the specific preparation steps are as follows:

[0043] (1) Weigh various raw materials according to the ratio, add water and silicate into a preparation device, and stir on a magnetic stirrer with a stirring speed of 200 - 300 r / min for 0.5 hours,

[0044] (2) Then successively add an activator, a hardening retarder, and a pH regulator, continue to stir for 0.5 - 1 hour, add the precursor of the overall framework structure while stirring, and continue to stir for 0.5 - 1 hour after adding to obtain the reaction liquid of this system,

[0045] (3) Conduct a hardening reaction at a temperature of 60 - 150 °C to obtain this silicate hardening type plugging system.

[0046] The third aspect of the present invention provides the application of the silicate hardening type plugging system in oil production.

[0047] The application of the silicate hardening type plugging system as a profile control agent for water injection wells, a water shutoff agent for oil wells, or a layer sealing agent for high water cut layers in oil production.

[0048] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, without conflict, they can be combined in any appropriate way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0049] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

[0050] The present invention will be further described below in conjunction with specific embodiments.

[0051] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and can be purchased.

[0052] In the following examples and comparative examples, without special instructions, all kinds of reagents used are commercially available chemically pure reagents.

[0053] Example 1:

[0054] Add 10 g of solid sodium silicate to 38.5 g of distilled water, stir on a magnetic stirrer for 0.5 h, and set the stirring speed to 200 r / min; while stirring, add 1.5 g of N,N-dimethylformamide, and continue stirring for 0.5 h to form a silicate hardening type plugging system; the components of the obtained silicate hardening type plugging system are calculated by mass percentage as: 20% water glass + 3% activator + 77% water. The gelation time of this system is 72 h at an ambient temperature of 60 °C and can be used as a profile control system for water wells.

[0055] Example 2:

[0056] Weigh 5 g each of sodium silicate and potassium silicate, add them to 33.5 g of distilled water, stir on a magnetic stirrer for 0.5 h, and set the stirring speed to 200 r / min; while stirring, add 1.5 g of N,N-dimethylformamide and 5 g of phenolic resin in sequence, and continue stirring for 0.5 h to form a silicate hardening type plugging system; the components of the obtained silicate hardening type plugging system are calculated by mass percentage as: 20% water glass + 3% activator + 5% precursor of the overall framework structure + 72% water. The gelation time of this system is 68 h at an ambient temperature of 60 °C and can be used as a profile control system for water wells.

[0057] Example 3:

[0058] Weigh 7.5 g of potassium silicate, add it to 31.5 g of distilled water, stir on a magnetic stirrer for 0.5 h, and set the stirring speed to 200 r / min; while stirring, add 1 g of N,N-dimethylformamide and 10 g of phenolic resin in sequence, and continue stirring for 0.5 h to form a silicate hardening type plugging system; the components of the obtained silicate hardening type plugging system are calculated by mass percentage as: 15% water glass + 2% activator + 10% precursor of the overall framework structure + 73% water. The gelation time of this system is 66 h at an ambient temperature of 80 °C and can be used as a profile control system for water wells.

[0059] Example 4:

[0060] Weigh 10 g of sodium silicate solution, add it to 28.25 g of distilled water, stir on a magnetic stirrer for 0.5 h, and set the stirring speed to 200 r / min. While stirring, add 1.5 g of urea, 10 g of phenolic resin, and 0.25 g of sodium hexametaphosphate in sequence, and continue to stir for 0.5 h to form a silicate hardening type plugging system. The components of the obtained silicate hardening type plugging system are calculated by mass percentage as follows: 20% water glass + 3% activator + 10% precursor of the overall framework structure + 0.5% delayed hardening agent + 66.5% water. The hardening time of this system at an ambient temperature of 90 °C is 60 h, and the plugging agent forms a reddish-brown solid after hardening. Apply a load to the solid surface and measure the compressive strength. The overall compressive strength of this plugging agent is measured to be 1.2 MPa, and it can be used as a water plugging system for oil wells.

[0061] Example 5:

[0062] First, add 12.5 g of sodium silicate solution to 33.25 g of distilled water, stir on a magnetic stirrer for 0.5 h, and set the stirring speed to 200 r / min. While stirring, add 1.5 g of urea, 2.5 g of phenolic resin prepolymer, and 0.25 g of sodium hexametaphosphate in sequence, and continue to stir for 0.5 h to form a silicate hardening type plugging system. The components of the obtained silicate hardening type plugging system are calculated by mass percentage as follows: 25% water glass + 3% activator + 5% precursor of the overall framework structure + 0.5% delayed hardening agent + 66.5% water. The hardening time of this system at an ambient temperature of 90 °C is 56 h, and the plugging agent forms a reddish-brown solid after hardening. Apply a load to the solid surface and measure the compressive strength. The overall compressive strength of this plugging agent is measured to be 3.5 MPa, and it can be used as a water plugging system for oil wells.

[0063] Example 6:

[0064] Add 0.4 g of sodium hydroxide and 12.5 g of sodium silicate solution to 32.1 g of distilled water, stir on a magnetic stirrer for 0.5 h, and set the stirring speed to 200 r / min. While stirring, add 1.24 g of formaldehyde, 1.26 g of phenol, 2 g of urea, and 0.5 g of sodium hexametaphosphate in sequence, and continue to stir for 0.5 h to form a silicate hardening type plugging system. The components of the obtained silicate hardening type plugging system are calculated by mass percentage as follows: 25% water glass + 4% activator + 5% precursor of the overall framework structure + 1% delayed hardening agent + 0.8% pH regulator + 64.8% water. The hardening time of this system at an ambient temperature of 120 °C is 48 h, and the plugging agent forms a reddish-brown solid after hardening. Apply a load to the solid surface and measure the compressive strength. The overall compressive strength of this plugging agent is measured to be 5.5 MPa, and it can be used as a water plugging system for oil wells and a sealing agent for high water-bearing layers.

[0065] Example 7:

[0066] Dissolve 2.5 g of methyl acetate in 39.25 g of distilled water, add 0.25 g of sodium hydroxide, then add 1.24 g of formaldehyde and 1.26 g of phenol in sequence. Stir on a magnetic stirrer for 0.5 h with the stirring speed set at 200 r / min. While stirring, add 15 g of sodium silicate solution and 0.5 g of sodium hexametaphosphate, and continue stirring for 0.5 h to form a silicate hardening type plugging system. The components of the obtained silicate hardening type plugging system are calculated by mass percentage as follows: 30% sodium silicate + 5% activator + 5% precursor of the overall framework structure + 1% delayed hardening agent + 0.5% pH regulator + 58.5% water. The hardening time of this system is 24 h at an ambient temperature of 150 °C, and the plugging agent forms a red-brown high-strength solid after hardening. It can be used as a water plugging system for oil wells and a sealing agent for high water cut layers.

[0067]

[0068]

[0069] Example 8:

[0070] Prepare a plugging agent system using the formula of the silicate hardening type plugging system in Example 6 and conduct a core physical simulation experiment.

[0071] Inject 1 PV of the silicate hardening type plugging system into cores with original water permeabilities of 12.5 mD, 125.5 mD, and 567.7 mD respectively. Cure the three cores at 120 °C for 48 h. After ensuring that the system is completely hardened, conduct subsequent water flooding. The measured post-plugging permeabilities are 0.95 mD, 10.1 mD, and 59.2 mD respectively, and the corresponding plugging rates are 94.4%, 92.0%, and 90.0% respectively, indicating that the system has a high plugging rate for cores with different permeabilities. After continuing subsequent water flooding for 30 PV, the decrease in the plugging rate is less than 0.5%, indicating that the plugging system has good plugging performance and erosion resistance, and is suitable for water plugging and profile control in medium-high permeability oil reservoirs.

[0072] Example 9:

[0073] Use the silicate plugging system in Example 7 to harden the sample, apply a load to the solid surface and measure the compressive strength. The overall compressive strength of the plugging agent is measured to be 10 MPa. Conduct a core physical simulation experiment using the system formula.

[0074] In cores with original water permeability of 10.5 mD, 227.6 mD, and 1002.7 mD, 1 PV of silicate hardening plugging system was injected respectively. After curing the three cores at 150 °C for 24 h to ensure complete hardening of the system, subsequent water flooding was carried out, and the post-plugging permeabilities were measured to be 0.5 mD, 20.1 mD, and 98.3 mD respectively, and the corresponding plugging rates were 95.2%, 91.2%, and 90.2% respectively, indicating that the system has a very high plugging rate for cores with different permeabilities; after continuing subsequent water flooding for 30 PV, the decrease in the plugging rate was less than 1%, indicating that the plugging system has good plugging performance and erosion resistance, and is suitable for water shutoff and profile control work in high-temperature medium-high permeability oil reservoirs.

[0075] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A silicate hardening type plugging system, characterized in that, the mass percentages of each component are as follows: 10% - 30% of silicate, 0.5 - 5% of activator, 0.5 - 10% of precursor of the overall skeleton structure, 0 - 1% of hardening retarder, pH regulator is 0.5% - 0.8%, and the balance is water, and the total composition is 100%.

2. The silicate hardening type plugging system according to claim 1, characterized in that, the silicate is one or a mixture of several of sodium silicate, potassium silicate, and lithium silicate.

3. The silicate hardening type plugging system according to claim 1, characterized in that, the activator is one of urea, methyl acetate, and N, N - dimethylformamide.

4. The silicate hardening type plugging system according to claim 1, characterized in that, the precursor of the overall skeleton structure is water - soluble phenolic resin or its prepolymer or monomer, forming a skeleton structure throughout the silica gel.

5. The silicate hardening type plugging system according to claim 1, characterized in that, the hardening retarder is one of sodium hexametaphosphate or nanocellulose.

6. The silicate hardening type plugging system according to claim 5, characterized in that, the pH regulator is one of sodium hydroxide or sodium bicarbonate.

7. A preparation method of the silicate hardening type plugging system according to any one of claims 1 - 6, characterized in that, the specific preparation steps are as follows: (1) Weigh various raw materials according to the ratio, add water and silicate into a preparator and stir; (2) Then add the activator, hardening retarder, and pH regulator in sequence, continue to stir, add the precursor of the overall skeleton structure while stirring, and continue to stir after adding to obtain the reaction liquid of this system; (3) Conduct a hardening reaction to obtain this silicate hardening type plugging system.

8. The preparation method of the silicate hardening type plugging system according to claim 7, characterized in that, the specific preparation steps are as follows: (1) Weigh various raw materials according to the ratio, add water and silicate into a preparator, and stir on a magnetic stirrer with a stirring speed of 200 - 300 r / min for 0.5 - 1 hour; (2) Then add the activator, hardening retarder, and pH regulator in sequence, continue to stir for 0.5 - 1 hour, add the precursor of the overall skeleton structure while stirring, and continue to stir for 0.5 - 1 hour after adding to obtain the reaction liquid of this system; (3) Conduct a hardening reaction at a temperature of 60 - 150 °C to obtain this silicate hardening type plugging system.

9. Application of the silicate hardening type plugging system according to any one of claims 1 - 6 in oil production.

10. Application of the silicate hardening type plugging system according to any one of claims 1 - 6 as a profile control agent for water wells, a water shut - off agent for oil wells, or a sealing agent for high - water - cut aquifers.

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