A nano-chemical sand consolidating agent and its preparation method

Abstract

The present invention belongs to the technical field of chemical sand control in oil and gas fields, and provides a nanochemical sand consolidating agent and a preparation method thereof. The raw material components of the nanochemical sand consolidating agent include, by weight percentage, 15-25% water-based binder, 15-25% binder-modified cross-linking agent, 0.5-1% clay stabilizer, 0.1-0.3% oil washing agent, 0.02-0.05% pH regulator, and the balance water; the raw material components of the binder-modified cross-linking agent include, by weight percentage, 30-50% phenolic modified micro-nano silica, 3-5% nano silica, and the balance water. The sand consolidating agent has excellent performance in formation sands of different particle sizes, high consolidation strength, high permeability of the consolidated core, and greatly reduced damage rate to the permeability of the consolidated core matrix.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical sand control in oil and gas fields and provides a nano chemical sand consolidating agent and a preparation method thereof. Background Art

[0002] During oil and gas field development, because most reservoirs consist of loose strata with low sand cement content and are typically cemented by contact, sand can easily break away from the rock under the influence of factors such as formation stress or fluid migration during production, and then flow into the wellbore with the fluid, resulting in sand production. Sand production poses numerous risks during oil and gas field development, including the deposition of gravel in the well, which can form sand plugs and increase the difficulty of crude oil processing, leading to reduced oil and gas production. It also wears out bottomhole and surface equipment, increasing development costs. Extensive sand production can lead to formation collapse, causing the well to be scrapped and shut down, and can also pollute the environment.

[0003] Currently, the most commonly used sand control methods are mechanical and chemical. Mechanical sand control involves lowering a sand control string into the sand-producing layer and using a screen to keep formation sand out of the wellbore. This sand control method places high demands on the screen selection. If the mesh size is too large, production capacity will be greatly affected, and fine sand will gradually clog the holes, causing the oil and gas well to stop production. If the mesh size is too small, it will not be able to effectively prevent sand particles from entering the wellbore. Its biggest disadvantage is that it is difficult to prevent fine sand particles with smaller particle sizes.

[0004] Chinese invention patent application CN106761590A discloses a multi-segment, high-density sand control method. Sand control tubing is run down an oil and water well, a packing tool is set, and gravel is injected for packing. However, this mechanical sand control method only protects against large sand particles in the formation, ranging in size from 65 to 64,000 μm, and is ineffective against smaller silt and mud. Furthermore, this method requires running tools down into the wellbore, significantly impacting subsequent well maintenance and increasing well repair costs.

[0005] Chemical sand control is the process of injecting sand-fixing agents into sand-producing formations. The commonly used sand-fixing agents at home and abroad are a series of products based on resins. By adding a curing agent to the resin, a high-strength cementing body is formed under a certain temperature and time. It can not only enhance the consolidation strength of the loose rock formation, but also form a sand barrier to block sand particles from far away in deeper positions in the formation. However, most of the current chemical sand control methods have poor sand control effects on fine silt and muddy sandstone, which is mainly reflected in low consolidation strength and high permeability damage.

[0006] Chinese invention patent application CN108949132A discloses a sand-fixing and unblocking treatment fluid, a sand-fixing treatment fluid system, and a sand-fixing method for fine silt reservoir oil wells. The components of the sand-fixing treatment fluid system work synergistically to form a bonding coating on the surface of fine siltstone and clay particles, which acts as a cementing and consolidating agent. However, the system incorporates additives such as corrosion inhibitors and stabilizers, making it unable to process cured resin materials. This also reduces the permeability of the formation, and the cured resin may cause the formation to produce no fluid, causing certain pollution to the reservoir. In addition, the sand-fixing treatment system does not have the ability to stabilize clay expansion and is not suitable for formations with a clay content greater than 10%. Its main function is to unblock, and its sand-fixing effect is average, with the possibility of fine silt appearing.

[0007] Chinese invention patent CN108949132B discloses a sand consolidation and plugging removal treatment fluid, a sand control fluid system, and a sand control method using the same for sand control in fine silt sand reservoirs. The sand consolidation and plugging removal treatment fluid comprises the following components by mass: 8-12% of a sand consolidation and plugging removal agent, 0.5-1.5% of a drainage aid, 0.5-1.5% of a corrosion inhibitor, 1-2% of an iron ion stabilizer, 1-2% of a mutual solvent, 1-2% of ammonium chloride, and the remainder is water. The system is further divided into a pretreatment fluid, a pre-fluid, a sand consolidation and plugging removal treatment fluid, and a displacement fluid, which need to be injected separately during the sand control process, which is relatively complicated.

[0008] Therefore, the sand production problem of fine silt and muddy sandstone still needs further research. Summary of the Invention

[0009] In view of the problems existing in the prior art, the present invention provides a nano chemical sand control agent for preventing fine silt and muddy sandstone from entering the wellbore.

[0010] To achieve the above-mentioned purpose, one of the technical solutions adopted by the present invention is to provide a nanochemical sand consolidating agent, which includes the following components, calculated by weight percentage: 15-25% water-based binder, 15-25% binder-modified cross-linker, 0.5-1% clay stabilizer, 0.1-0.3% oil washing agent, 0.02-0.05% pH regulator and the balance water.

[0011] Preferably, the binder-modified cross-linking agent comprises the following components by weight percentage: 30-50% phenolic modified micro-nano silica, 3-5% nano silica and the balance water.

[0012] Preferably, the preparation of the binder-modified crosslinker specifically comprises the following steps:

[0013] (1) Add phenolic modified micro-nano silica and nano-silica into water and stir evenly;

[0014] (2) Raise the temperature and stir once; continue to raise the temperature and stir twice.

[0015] Preferably, in step (2), the first stirring temperature is 25-35° C., and the stirring time is 0.5-2 hours; the second stirring temperature is 40-50° C., and the stirring time is 2-4 hours.

[0016] More preferably, in step (2), the first stirring temperature is 30° C., and the stirring time is 1 hour; the second stirring temperature is 45° C., and the stirring time is 3 hours.

[0017] Preferably, the water-based binder is at least one of polyvinyl alcohol, polyvinyl acetate, polyacrylate, styrene block copolymer, and glycidyl ether-modified polyoxyethylene.

[0018] More preferably, the water-based binder is at least one of glycidyl ether-modified polyoxyethylene and polyvinyl alcohol.

[0019] Preferably, the clay stabilizer is at least one of dimethylallylammonium chloride, epoxypropyltrimethylammonium chloride, 2-chloroethyltrimethylammonium chloride, tetramethylammonium chloride, benzyltrimethylammonium chloride, 2-hydroxyethyltrimethylammonium chloride, diethylenetriamine salt, and tetraethylenepentamine salt.

[0020] More preferably, the clay stabilizer is at least one of tetramethylammonium chloride and tetraethylene pentamine salt.

[0021] Preferably, the oil cleaning agent is at least one of alkylbenzene sulfonate, alkyl sulfate, petroleum sulfonate, alkyl hydroxypropyl sulfobetaine, mixed carbon chain isomerized alcohol polyoxyethylene ether, and alkyl glycoside.

[0022] More preferably, the oil washing agent is at least one of petroleum sulfonate and fatty alcohol polyoxyethylene ether.

[0023] Preferably, the pH regulator is at least one of sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0024] More preferably, the pH regulator is sodium hydroxide.

[0025] The second technical solution adopted by the present invention is to provide a method for preparing a high-efficiency nanochemical sand consolidating agent, which specifically includes the following steps:

[0026] (1) Add clay stabilizer and oil washing agent to water and stir to obtain mixed solution 1;

[0027] (2) adding a water-based binder and a binder-modified cross-linking agent to the mixed solution 1; continuing to stir to obtain a mixed solution 2;

[0028] (3) A pH regulator is added to the mixed solution 2 to obtain a nano-chemical sand consolidating agent.

[0029] Preferably, the stirring time in step (1) is 1-3 min; and the stirring time in step (3) is 3-5 min.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The nano-chemical sand consolidation agent of the present invention has a significant synergistic sand consolidation effect under the joint action of the water-based binder and the cross-linking agent; and compared with phenolic modified micro-nano silica as a cross-linking agent, the sand consolidation agent prepared by the binder modified cross-linking agent used in the present invention has a better sand consolidation effect;

[0032] 2. The present invention has good consolidation performance in formation sands of different particle sizes, with a consolidation strength of 8-17 MPa, which is higher than most resin sand consolidating agents; the permeability of the consolidated core is significantly better than that of the resin sand consolidating agent, and the permeability of 20 / 40 mesh quartz sand after consolidation is as high as 30 μm 2 , the permeability of 100 / 140 mesh silt sand after consolidation reaches 3.1μm 2 ; It has a wider range of applications and has excellent consolidation effects on coarse sand, medium sand, fine sand and silt, especially achieving the sand consolidation effect on nano-silt, and has a wider range of uses;

[0033] 3. The nano-chemical sand consolidation agent of the present invention has extremely low damage to the consolidated core, with the maximum damage rate to the core matrix permeability being only 21.8%, while the resin sand consolidation agent has a damage rate as high as 89.3%;

[0034] 4. The present invention adopts a water-based binder to bind the sand particles at the contact points, and cooperates with the curing effect of the binder-modified cross-linking agent. In particular, under the joint action of the water-based binder and phenolic modified micro-nano silica and nano silica, an artificial well wall is formed, which increases the consolidation effect on fine sand, and there is no residue left in the well, making remedial operations convenient. DETAILED DESCRIPTION

[0035] It is worth noting that the raw materials used in the present invention are all common commercially available products, and their sources are not specifically limited.

[0036] The following raw material sources are illustrative:

[0037] Glycidyl ether-modified polyoxyethylene was purchased from Shaanxi Mingrui Petroleum Technology Co., Ltd.

[0038] Petroleum sulfonate (KPS), Karamay Jinta Chemical Co., Ltd.;

[0039] Phenolic modified micro-nano silica was purchased from Shaanxi Mingrui Petroleum Technology Co., Ltd.

[0040] Nano-silicon dioxide (30 nm) was purchased from Ningbo Luofei Nanotechnology Co., Ltd.

[0041] Example 1:

[0042] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 20% of glycidyl ether modified polyoxyethylene, 20% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0043] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0044] Preparation method of binder modified crosslinker:

[0045] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0046] A preparation method of nano chemical sand consolidating agent:

[0047] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0048] Example 2:

[0049] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 20% of glycidyl ether modified polyoxyethylene, 20% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0050] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 45% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0051] Preparation method of binder modified crosslinker:

[0052] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0053] A preparation method of nano chemical sand consolidating agent:

[0054] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0055] Example 3

[0056] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 25% of glycidyl ether modified polyoxyethylene, 20% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0057] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0058] Preparation method of binder modified crosslinker:

[0059] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0060] A preparation method of nano chemical sand consolidating agent:

[0061] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0062] Example 4

[0063] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 20% of glycidyl ether modified polyoxyethylene, 25% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0064] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0065] Preparation method of binder modified crosslinker:

[0066] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0067] A preparation method of nano chemical sand consolidating agent:

[0068] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0069] Example 5

[0070] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 20% of glycidyl ether modified polyoxyethylene, 20% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.05% of sodium hydroxide, and the balance of water;

[0071] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0072] Preparation method of binder modified crosslinker:

[0073] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0074] A preparation method of nano chemical sand consolidating agent:

[0075] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0076] Comparative Example 1:

[0077] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 40% of glycidyl ether-modified polyoxyethylene, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide and the balance of water;

[0078] A preparation method of nano chemical sand consolidating agent:

[0079] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0080] Comparative Example 2:

[0081] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 20% of glycidyl ether modified polyoxyethylene, 20% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0082] The binder-modified cross-linking agent comprises, based on a total weight of 100%, 39% of phenolic modified micro-nano silica and the balance of water.

[0083] Preparation method of binder modified crosslinker:

[0084] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica and the balance of water according to the above weight percentage, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0085] A preparation method of nano chemical sand consolidating agent:

[0086] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0087] Comparative Example 3:

[0088] A nano chemical sand consolidating agent, comprising, based on 100% of the total weight, 20% of glycidyl ether modified polyoxyethylene, 20% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0089] The binder-modified cross-linking agent comprises 39% of nano-silicon dioxide and the balance of water, based on a total weight of 100%.

[0090] Preparation method of binder modified crosslinker:

[0091] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica and the balance of water according to the above weight percentage, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0092] A preparation method of nano chemical sand consolidating agent:

[0093] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0094] Comparative Example 4:

[0095] A nano chemical sand consolidating agent, comprising, based on 100% of its total weight, 40% of a binder-modified cross-linking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.02% of sodium hydroxide, and the balance of water;

[0096] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0097] Preparation method of binder modified crosslinker:

[0098] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0099] A preparation method of nano chemical sand consolidating agent:

[0100] Measure 100mL of clean water and pour it into a 500mL cup. Set the stirring speed to 300r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentage, stir for 1 minute, then add the binder-modified cross-linking agent, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0101] Comparative Example 5:

[0102] The only difference from Example 1 is that the nano chemical sand consolidation agent, based on 100% of the total weight, comprises: 10% of glycidyl ether modified polyoxyethylene, 10% of a binder modified cross-linking agent;

[0103] A nano chemical sand consolidating agent, comprising, based on 100% of its total weight, 10% of glycidyl ether modified polyoxyethylene, 10% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.05% of sodium hydroxide, and the balance of water;

[0104] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0105] Preparation method of binder modified crosslinker:

[0106] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0107] A preparation method of nano chemical sand consolidating agent:

[0108] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0109] Comparative Example 6:

[0110] The only difference from Example 1 is that the nano chemical sand consolidation agent, based on 100% of the total weight, comprises: 30% of glycidyl ether modified polyoxyethylene, 30% of a binder modified cross-linking agent;

[0111] A nano chemical sand consolidating agent, comprising, based on 100% of its total weight, 30% of glycidyl ether modified polyoxyethylene, 30% of a binder modified crosslinking agent, 0.5% of tetramethylammonium chloride, 0.1% of petroleum sulfonate, 0.05% of sodium hydroxide, and the balance of water;

[0112] The binder-modified cross-linking agent, based on a total weight of 100%, comprises: 35% of phenolic modified micro-nano silicon dioxide, 4% of nano silicon dioxide and the balance of water.

[0113] Preparation method of binder modified crosslinker:

[0114] In a reactor equipped with a heating and stirring device, add phenolic modified micro-nano silica, nano silica and the balance of water according to the above weight percentages, stir evenly, heat to 30°C and stir for 1 hour, continue to heat to 45°C and stir for 3 hours, and then cool to obtain the binder modified crosslinker.

[0115] A preparation method of nano chemical sand consolidating agent:

[0116] Measure 100 mL of clean water and pour it into a 500 mL cup. Set the stirring speed to 300 r / min. Add tetramethylammonium chloride and petroleum sulfonate into the water according to the above weight percentages, stir for 1 minute, then add glycidyl ether modified polyoxyethylene and binder modified cross-linking agent respectively, stir for 3 minutes, and finally add sodium hydroxide to prepare the required chemical sand consolidation agent.

[0117] Test example

[0118] The compressive strength and the Kerchler permeability of the cured cores prepared in the above examples and comparative examples were tested in accordance with the QSY17378-2022 "Sand Control Resins for Oil and Gas Production" testing standard;

[0119] The core matrix permeability damage rate was tested by simulating the sand consolidation agent to penetrate into the reservoir matrix and solidify, and the gas permeability was 0.1-0.2μm. 2 A natural core with a particle size of 20 / 40 mesh and a mud content of ≤20% was placed in a core permeability tester. After injecting 2PV of the prepared chemical sand consolidation agent, the inlet and outlet of the core holder were sealed and the temperature was raised to 80°C. After 24 hours, the permeability of the core after damage was tested. The damage rate of the core matrix permeability = (core permeability before damage - core permeability after damage) / core permeability before damage * 100%.

[0120] The performance indicators of the chemical sand consolidating agents prepared in the examples and comparative examples are shown in Table 1. It can be seen from Table 1 that with the addition of water-based binders and binder-modified cross-linkers, the performance parameters of the core after the chemical sand consolidating agent and quartz sand are excellent, far exceeding similar products in the industry; the addition of single components of water-based binders and binder-modified cross-linkers has poor application effects; the simultaneous use of water-based binders and phenolic modified micro-nano silica, the main component of the binder-modified cross-linker, also produces relatively good results, but the various performance indicators still cannot reach the effect of using water-based binders and binder-modified cross-linkers at the same time.

[0121] Table 1 Performance indicators of chemical sand consolidation agents

[0122]

[0123]

[0124] The core compressive strength (Mpa) and Kerrey permeability of the chemical sand consolidating agents prepared in various embodiments of the present invention and the commercially available epoxy resin sand consolidating agents after curing quartz sand of different mesh sizes are shown in Tables 2 and 3.

[0125] Table 2 Compressive strength index of consolidated core

[0126]

[0127] Table 3 Permeability index of consolidated core

[0128]

[0129] The compressive strength of the chemical sand consolidating agent prepared in each embodiment of the present invention on 20 / 40 mesh quartz sand is as high as 15.36 MPa and the permeability is as high as 30.12 μm. 2 The compressive strength of 100 / 140 mesh silt after consolidation is as high as 12.83MPa and the permeability reaches 3.10μm. 2 The compressive strength of commercially available epoxy resin sand consolidation agent 20 / 40 mesh quartz sand after consolidation is only 5.61MPa and the permeability is 2.60μm. 2 ; The 100 / 140 mesh silt sand is not cemented, and the compressive strength and permeability cannot be measured; the sand consolidating agent of the present invention has excellent consolidation effect on coarse sand, medium sand, fine sand and silt sand, and has a wider range of uses.

[0130] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A nano-chemical sand consolidation agent, characterized in that: The composition comprises the following components by weight percentage: 15-25% water-based binder, 15-25% binder-modified cross-linking agent, 0.5-1% clay stabilizer, 0.1-0.3% oil washing agent, 0.02-0.05% pH regulator and the balance water; The binder modified cross-linking agent comprises the following components by weight percentage: 30-50% phenolic modified micro-nano silica, 3-5% nano silica and the balance water; The water-based binder is at least one of polyvinyl alcohol, polyvinyl acetate, polyacrylate, styrene block copolymer and glycidyl ether modified polyoxyethylene.

2. The nanochemical sand consolidation agent according to claim 1, characterized in that: The preparation method of the binder-modified cross-linking agent comprises the following steps: (1) Add phenolic modified micro-nano silica and nano-silica into water and stir evenly; (2) Raise the temperature and stir once; continue to raise the temperature and stir twice.

3. The nanochemical sand consolidation agent according to claim 2, characterized in that: In step (2), the first stirring temperature is 25-35°C, and the stirring time is 0.5-2 hours; the second stirring temperature is 40-50°C, and the stirring time is 2-4 hours.

4. The nanochemical sand consolidation agent according to claim 1, characterized in that: The clay stabilizer is at least one of dimethylallylammonium chloride, epoxypropyltrimethylammonium chloride, 2-chloroethyltrimethylammonium chloride, tetramethylammonium chloride, benzyltrimethylammonium chloride, 2-hydroxyethyltrimethylammonium chloride, diethylenetriamine salt and tetraethylenepentamine salt.

5. The nanochemical sand consolidation agent according to claim 1, characterized in that: The oil washing agent is at least one of alkylbenzene sulfonate, alkyl sulfate, petroleum sulfonate, alkyl hydroxypropyl sulfobetaine, mixed carbon chain isomerized alcohol polyoxyethylene ether and alkyl glycoside.

6. The nanochemical sand consolidation agent according to claim 1, characterized in that: The pH regulator is at least one of sodium hydroxide, sodium carbonate and sodium bicarbonate.

7. The nanochemical sand consolidation agent according to claim 1, characterized in that: The water-based binder is at least one of glycidyl ether-modified polyoxyethylene and polyvinyl alcohol.

8. The nanochemical sand consolidation agent according to claim 1, characterized in that: The clay stabilizer is at least one of tetramethylammonium chloride and tetraethylene pentamine salt.

9. The nanochemical sand consolidation agent according to claim 1, characterized in that: The oil washing agent is at least one of petroleum sulfonate and fatty alcohol polyoxyethylene ether.

10. The nanochemical sand consolidation agent according to claim 1, characterized in that: The pH regulator is sodium hydroxide.

11. The method for preparing a chemical sand consolidating agent according to any one of claims 1 to 10, characterized in that: The specific steps include: (1) Add clay stabilizer and oil washing agent to water and stir to obtain mixed solution 1; (2) Adding a water-based binder and a binder-modified cross-linking agent to the mixed solution 1; continuing to stir to obtain a mixed solution 2; (3) Adding a pH regulator to the mixed solution 2, a nano-chemical sand consolidating agent is obtained.

12. The method for preparing a chemical sand consolidating agent according to claim 11, characterized in that: In step (1), the stirring temperature is room temperature, and the stirring time is 1-3 min; in step (3), the stirring temperature is room temperature, and the stirring time is 3-5 min.

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