Permeable drilling wall protecting fluid as well as preparation method and application thereof

Abstract

The invention relates to the technical field of highway bridge pile foundation construction, and particularly discloses permeation type drilling wall protection liquid as well as a preparation method and application thereof. The drilling wall protection liquid comprises the following components in percentage by weight: 2.0%-8.0% of silica fume, 0.3%-1.2% of aluminum potassium sulfate, 2.5%-6.0% of sodium bicarbonate, 2.0%-5.2% of calcium chloride, 0.2%-0.6% of an organic polymer, 7.0%-15.0% of an anionic surfactant, 0.1%-0.6% of a silane water repellent, 5.0%-10.0% of a gel consolidation agent and the balance of water. The permeation type drilling wall protection fluid provided by the invention has good comprehensive performance, can improve the drilling capacity and the drilling speed, ensures the drilling stability, remarkably reduces the occurrence of hole wall instability accidents in the pile foundation drilling process, improves the success rate, and can provide reliable guarantee for various foundation engineering construction.

Description

Technical Field

[0001] This invention relates to the field of highway bridge pile foundation construction technology, and in particular to a penetrating drilling wall protection fluid, its preparation method, and its application. Background Technology

[0002] With the continuous development of highway construction, bored piles are widely used in foundation infrastructure projects such as highways, railways, bridges, water conservancy projects, and urban construction projects. Bored piles refer to piles constructed by mechanically drilling holes in the foundation soil on-site, filling them with concrete, or by first placing a reinforcing cage in the hole and then pouring concrete. The wall-protecting fluid is a mixed slurry composed of water, clay, and additives. During drilling, the wall-protecting fluid circulates, maintaining the pressure difference between the hole and the hole wall, forming a slurry skin to reinforce the hole wall, and also serving multiple functions such as cooling and lubricating the drill bit, stabilizing the water level, and suspending drill cuttings. Water-based drilling mud has become the most commonly used wall-protecting material in bored pile construction due to its relatively low cost, readily available raw materials, and minimal environmental impact. Water-based drilling mud typically uses bentonite as its main component, with various chemical treatment agents added to adjust its properties. However, existing water-based drilling muds have revealed a series of problems that urgently need to be addressed in practical applications.

[0003] On the one hand, bentonite-based drilling mud is prone to stratification during the wall-protection process due to its physicochemical properties. This stratification leads to inconsistent properties in different parts of the mud, severely weakening its wall-protection effect and significantly increasing the risk of borehole collapse, causing serious safety hazards and economic losses to the project. On the other hand, bentonite drilling mud has the characteristic of suspending mud and sand, making it difficult for the mud and sand generated during drilling to settle effectively. In actual construction, the mud and sand generated during drilling, once carried into the borehole by the bentonite drilling mud, will remain for a long time due to the high viscosity and colloidal stability of the mud, eventually accumulating at the bottom of the pile to form a large amount of sediment. The presence of sediment at the pile bottom not only increases the resistance of underwater concrete pouring, causing a significant reduction in the flow radius of the concrete, but may also cause problems such as exposed reinforcing cages, seriously affecting the quality of the pile body and reducing the bearing capacity and durability of the cast-in-place pile. In addition, under certain special geological conditions, such as in medium sand and gravel strata with larger particles, higher permeability, and higher porosity, the existing wall protection mud has a high leakage rate. This not only causes a large waste of wall protection materials and increases construction costs, but may also lead to insufficient wall protection fluid to effectively maintain borehole stability, further exacerbating the risk of borehole collapse.

[0004] Therefore, there is an urgent need to develop a new type of borehole wall protection fluid that can not only improve the mechanical drilling speed and solve the problem of mud blockage, but also enhance the wall protection and anti-collapse capabilities, efficiently carry cuttings and promote the settling of rock cuttings, so as to meet the high-quality and high-efficiency construction requirements of modern engineering. Summary of the Invention

[0005] To address the problems of poor borehole wall protection effect, easy borehole collapse, significant sediment buildup, high sand content, thick mud cake, long cleaning time, and large mud consumption in existing borehole wall protection fluids, this invention provides a penetrating borehole wall protection fluid, its preparation method, and its application. The penetrating borehole wall protection fluid provided by this invention can rapidly penetrate into the pores of the borehole wall, tightly bonding with soil and rock particles to form a high-strength impermeable layer, significantly enhancing borehole wall stability and greatly reducing the risk of borehole collapse. Simultaneously, its unique rheological properties enable it to effectively suspend rock cuttings during the cuttings-carrying process and promote rapid settling of rock cuttings during borehole cleaning, significantly reducing the thickness of sediment at the pile bottom and the sand content of the mud, providing efficient and reliable technical support for infrastructure construction such as highways and railways.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage: silica fume 2.0%–8.0%, potassium aluminum sulfate 0.3%–1.2%, sodium bicarbonate 2.5%–6.0%, calcium chloride 2.0%–5.2%, organic polymer 0.2%–0.6%, anionic surfactant 7.0%–15.0%, silane hydrophobic agent 0.1%–0.6%, gelling agent 5.0%–10.0%, and the balance being water;

[0008] The organic polymer is one or both of plant gum or water-soluble sodium hydroxyethyl cellulose.

[0009] Compared to existing technologies, the permeable borehole wall protection fluid provided by this invention utilizes silica fume to effectively increase the fluid's viscosity, reduce filtration loss, and decrease the risk of soil softening caused by water seepage into the borehole wall. Simultaneously, the active silica in the silica fume reacts with calcium and magnesium ions in the soil and rock to form a cementitious substance that fills the pores. After thorough mixing with the gelling agent, a highly permeable slurry is formed, rapidly penetrating the borehole wall. Upon solidification, it forms a thin and dense mud cake that adheres tightly to the borehole wall. Compared to the thicker mud cake formed by traditional bentonite slurry, this mud cake is more uniform and compact, with a significantly reduced thickness.

[0010] Organic polymers can form a tough film on the soil surface, effectively sealing capillary channels and preventing soil spalling from the borehole wall due to moisture loss or pressure changes. This provides an additional protective barrier for the borehole wall, reducing sand and soil introduced into the mud due to spalling and controlling the increase in mud sand content at the source. During concrete pouring, the new mud cake forms a strong mechanical interlocking structure with the concrete, significantly improving their bonding performance. This tight bond greatly reduces resistance during concrete pouring, avoiding defects such as incomplete reinforcement cage wrapping caused by poor pouring. Simultaneously, the significantly increased friction between the mud cake and concrete enhances the interaction between the pile and the surrounding soil, effectively improving the bearing capacity and long-term durability of the pile foundation.

[0011] Sodium bicarbonate reacts with potassium aluminum sulfate to release carbon dioxide, which on the one hand promotes the coagulation and solidification of the gel consolidator, accelerates the formation of the gel network, and enhances the borehole wall strength. On the other hand, the generated sodium carbonate can adjust the pH of the wall-protecting fluid to a weakly alkaline environment, causing calcium and magnesium ions to react and form precipitates, increasing the colloidal content and stability of the wall-protecting fluid, and preventing drill bit corrosion or borehole wall collapse caused by abnormal pH values. Silane-based hydrophobic agents penetrate and form a hydrophobic film on the borehole wall surface, reducing water osmotic pressure, working synergistically with the gel consolidator to seal micropores, and binding soil and rock particles into a whole, significantly improving the borehole wall's shear strength and significantly reducing the risk of borehole collapse.

[0012] Anionic surfactants reduce surface tension, disperse colloidal solutions, and prevent suspension and stratification, forming a stable hydration film on the rock cuttings surface. Combined with the thickening effect of organic polymers, this maintains the suspension of rock cuttings during drilling, preventing them from accumulating at the bottom of the hole and forming high-sand-content areas due to gravity settling. During hole cleaning, potassium aluminum sulfate acts as a flocculant, disrupting the colloidal stability of the rock cuttings and drilling mud, promoting rapid settling of the rock cuttings, significantly improving hole cleaning efficiency, effectively shortening the overall construction cycle, and providing a reliable guarantee for project progress.

[0013] In easily collapsed strata such as medium-coarse sand layers, the hydrophobic agent forms a hydrophobic layer through the "reverse capillary effect," preventing water penetration and sand loss. Silica fume and gel consolidating agents quickly seal micro-fractures, while potassium aluminum sulfate accelerates the settling of coarse particles, preventing rock debris accumulation that could lead to collapse. Compared with traditional wall-protecting fluids, this invention can significantly reduce mud loss, providing reliable technical support for special geological construction.

[0014] Through the synergistic effect of its components, the drilling fluid exhibits superior performance in engineering applications. It possesses unique rheological control characteristics. In a static state, the fluid is gel-like, effectively inhibiting drill cuttings settling and maintaining stable suspension of solid particles within the borehole. When the drill bit is in operation, it rapidly transforms into a low-viscosity fluid under shear force, significantly reducing drill bit resistance and improving drilling efficiency. After operation ceases, the fluid's viscosity quickly recovers, reforming a stable suspension system and ensuring the stability and continuity of the drilling process.

[0015] It should be noted that the plant gums mentioned in this invention include at least one of guar gum, sesame gum, sesame gum, and coumarin gum. The main component is galactomannan, and there are also proteins, cellulose, water, and small amounts of inorganic elements such as calcium and magnesium.

[0016] Furthermore, the penetrating drilling wall protection fluid comprises the following raw material components by mass percentage: silica fume 3.8%–7.6%, potassium aluminum sulfate 0.4%–0.8%, sodium bicarbonate 2.8%–5.8%, calcium chloride 3.0%–4.8%, organic polymer 0.3%–0.5%, anionic surfactant 7.0%–12.0%, silane hydrophobic agent 0.2%–0.4%, gelling agent 6.5%–8.5%, and the balance being water.

[0017] Furthermore, the penetrating drilling wall protection fluid comprises the following raw material components by mass percentage: silica fume 5.5%–7.6%, potassium aluminum sulfate 0.5%–0.8%, sodium bicarbonate 3.6%–5.8%, calcium chloride 3.8%–4.8%, organic polymer 0.3%–0.4%, anionic surfactant 9.0%–9.5%, silane hydrophobic agent 0.3%–0.4%, gelling agent 8.0%–8.5%, and the balance being water.

[0018] Furthermore, the anionic surfactant is one or both of sodium polyacrylate or sodium polycarboxylate.

[0019] The aforementioned preferred surfactants can uniformly disperse the colloidal solution through electrostatic repulsion and steric hindrance effects, effectively preventing suspension and stratification. During drilling, they rapidly adsorb onto the surface of rock cuttings, forming a stable hydration film, greatly improving the suspension stability of rock cuttings in the wall-supporting fluid, ensuring uniform dispersion and preventing sedimentation. The surfactants reduce surface tension and disperse particles, while the organic polymers increase viscosity; these two elements complement each other, ensuring stable suspension of rock cuttings during drilling without excessively increasing fluid resistance and affecting drilling efficiency, thus providing a reliable guarantee for efficient drilling operations.

[0020] Furthermore, the silane-based hydrophobic agent is one or both of polydimethylsiloxane or isooctyltriethoxysilane.

[0021] The selected water-repellent agent has extremely low surface tension, allowing it to quickly penetrate into the pores of the borehole wall. It reacts chemically with the borehole wall material, forming a dense water-repellent layer through silanol crosslinking. This creates a waterproof layer on the borehole wall surface, effectively preventing water penetration and reducing the risk of soil softening and collapse due to water erosion. After penetrating the borehole wall, the water-repellent agent not only provides waterproofing but also fills and reinforces the pore structure, enhances the bonding force between soil particles, and improves the density and shear strength of the borehole wall. This allows the borehole wall to better resist external forces during drilling and grouting, reducing the occurrence of borehole collapse accidents and improving the adaptability of the wall-protecting fluid under complex geological conditions.

[0022] Furthermore, the gelling agent is one or both of aqueous sodium silicate or aqueous polyurethane.

[0023] Preferably, the gelling agent is aqueous sodium silicate.

[0024] Specifically, the aqueous sodium silicate has a modulus of 2.5 to 2.8 and a density of 1.35 g / cm³. 3 ~1.50g / cm 3 .

[0025] Sodium silicate reacts with calcium chloride to form silica gel and calcium silicate gel. Under alkaline conditions, these react with calcium and magnesium ions to form precipitates, which encapsulate soil particles and fill pores, allowing the originally loose soil particles to connect with each other. After hardening, the silica gel and calcium silicate gel form a unique silica network framework structure with a large specific surface area and high bonding strength. This structure not only cements and firmly fixes soil particles but also fills the gaps between them, making the soil structure denser and more stable. In this way, the soil is effectively consolidated, significantly improving its strength and bearing capacity, and greatly enhancing the stability of the pore walls, thus effectively preventing pore collapse.

[0026] It should be noted that when two of the organic polymers, anionic surfactants, silane hydrophobic agents, and gelling agents specified in this invention are used in combination, there is no special limitation on the combination ratio of the two substances. Any combination of the two substances within any ratio range can achieve the same technical effect as a single substance.

[0027] Secondly, the present invention also provides a method for preparing a penetrating borehole wall protection fluid, comprising the following steps:

[0028] Weigh each component according to the design ratio of the permeable drilling wall protection fluid described in any of the above items, dissolve the weighed silica fume, potassium aluminum sulfate and calcium chloride in water, then add the weighed anionic surfactant and silane hydrophobic agent in sequence, mix evenly, add organic polymer, dissolve, add gel solidifying agent and sodium bicarbonate, mix evenly to obtain the permeable drilling wall protection fluid.

[0029] Specifically, the weighed silica fume, potassium aluminum sulfate and calcium chloride are added to water at 20℃~30℃ and stirred at 800r / min~1200r / min for 15min~20min.

[0030] Specifically, after adding anionic surfactant and hydrophobic agent, stir at 800r / min to 1200r / min for 10min to 15min.

[0031] Specifically, after adding the organic polymer, stir at 4000r / min to 6000r / min for 30min to 40min.

[0032] The preparation method of the permeable drilling wall protection fluid provided by this invention is simple and suitable for industrial-scale production.

[0033] Thirdly, the present invention also provides the application of the above-mentioned penetrating drilling wall protection fluid in pile foundation drilling construction.

[0034] The permeable drilling wall protection fluid provided by this invention has excellent comprehensive performance, which can improve drilling capacity and drilling speed, ensure drilling stability, and significantly reduce the occurrence of borehole instability accidents during pile foundation drilling, thereby increasing the success rate. Moreover, the wall protection fluid can be recycled, significantly reducing mud consumption and effectively lowering transportation costs. At the same time, the wall protection fluid is suitable for pile foundation drilling construction in medium sand and gravel strata, and can provide reliable protection for various foundation engineering constructions. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Example 1

[0037] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0038] 5.5% silica fume, 0.5% potassium aluminum sulfate, 3.6% sodium bicarbonate, 3.8% calcium chloride, 0.3% plant gum, 9.5% sodium polycarboxylate, 0.3% polydimethylsiloxane, 8.5% aqueous sodium silicate, with the balance being water.

[0039] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0040] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 1000 r / min for 20 min. Add sodium polycarboxylate and polydimethylsiloxane in sequence and continue stirring at 1000 r / min for 15 min. Then add plant gum and stir at 5000 r / min for 35 min. Finally, add water-based sodium silicate and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0041] Example 2

[0042] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0043] 5.0% silica fume, 0.7% potassium aluminum sulfate, 2.8% sodium bicarbonate, 4.0% calcium chloride, 0.5% plant gum, 10.0% sodium polyacrylate, 0.4% polydimethylsiloxane, 6.6% waterborne polyurethane, with the balance being water.

[0044] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0045] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 1050 r / min for 20 min. Add sodium polyacrylate and polydimethylsiloxane in sequence and continue stirring at 1050 r / min for 15 min. Then add plant gum and stir at 5500 r / min for 35 min. Finally, add waterborne polyurethane and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0046] Example 3

[0047] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0048] 3.8% silica fume, 0.6% potassium aluminum sulfate, 4.2% sodium bicarbonate, 3.0% calcium chloride, 0.4% plant gum, 12.0% sodium polycarboxylate, 0.2% isooctyltriethoxysilane, 6.5% aqueous sodium silicate, with the balance being water.

[0049] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0050] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 1100 r / min for 16 min. Add sodium polycarboxylate and isooctyltriethoxysilane in sequence and continue stirring at 1100 r / min for 11 min. Then add plant gum and stir at 4800 r / min for 38 min. Finally, add aqueous sodium silicate and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0051] Example 4

[0052] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0053] The composition is as follows: silica fume 6.8%, potassium aluminum sulfate 0.4%, sodium bicarbonate 5.8%, calcium chloride 3.3%, water-soluble sodium hydroxyethyl cellulose 0.3%, sodium polyacrylate 7.0%, isooctyltriethoxysilane 0.2%, aqueous sodium silicate 7.2%, and the balance is water.

[0054] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0055] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 950 r / min for 20 min. Add sodium polyacrylate and isooctyltriethoxysilane in sequence and continue stirring at 950 r / min for 12 min. Then add water-soluble sodium hydroxyethyl cellulose and stir at 5500 r / min for 30 min. Finally, add water-based sodium silicate and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0056] Example 5

[0057] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0058] 7.6% silica fume, 0.8% potassium aluminum sulfate, 5.2% sodium bicarbonate, 4.8% calcium chloride, 0.4% water-soluble sodium hydroxyethyl cellulose, 4% sodium polyacrylate, 5% sodium polycarboxylate, 0.3% polydimethylsiloxane, 8.1% aqueous sodium silicate, with the balance being water.

[0059] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0060] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 900 r / min for 18 min. Then add sodium polyacrylate, sodium polycarboxylate, and polydimethylsiloxane in sequence. Continue stirring at 800 r / min for 13 min. Then add water-soluble sodium hydroxyethyl cellulose and stir at 4500 r / min for 35 min. Finally, add water-based sodium silicate and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0061] Example 6

[0062] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0063] 2.2% silica fume, 1.2% potassium aluminum sulfate, 2.5% sodium bicarbonate, 2.0% calcium chloride, 0.6% plant gum, 8.6% sodium polyacrylate, 0.1% polydimethylsiloxane, 5.2% aqueous sodium silicate, with the balance being water.

[0064] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0065] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 1200 r / min for 15 min. Add sodium polyacrylate and polydimethylsiloxane in sequence and continue stirring at 1200 r / min for 10 min. Then add plant gum and stir at 4000 r / min for 40 min. Finally, add water-based sodium silicate and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0066] Example 7

[0067] This invention provides a penetrating drilling wall protection fluid, comprising the following raw material components by mass percentage:

[0068] 3.5% silica fume, 0.3% potassium aluminum sulfate, 3.6% sodium bicarbonate, 5.2% calcium chloride, 0.2% water-soluble sodium hydroxyethyl cellulose, 15.0% sodium polyacrylate, 0.3% polydimethylsiloxane, 0.3% isooctyltriethoxysilane, 4.5% water-based sodium silicate, 5.4% water-based polyurethane, with the balance being water.

[0069] The preparation method of the above-mentioned penetrating drilling wall protection fluid includes the following steps:

[0070] Weigh each component according to the above proportions. Add the weighed silica fume, potassium aluminum sulfate, and calcium chloride to the water in the mixing tank. Control the water temperature at 20-30℃ and stir at 800 r / min for 20 min. Add sodium polyacrylate and water-repellent agent in sequence and continue stirring at 800 r / min for 15 min. Then add water-soluble sodium hydroxyethyl cellulose and stir at 6000 r / min for 30 min. Finally, add water-based polyurethane and sodium bicarbonate and stir until the slurry meets the technical requirements to obtain a penetrating drilling wall protection fluid.

[0071] Comparative Example 1

[0072] This comparative example provides a drilling wall protection fluid, which differs from Example 1 only in that bentonite is used instead of silica fume. The specific composition is as follows:

[0073] Bentonite 5.5%, potassium aluminum sulfate 0.5%, sodium bicarbonate 3.6%, calcium chloride 3.8%, plant gum 0.3%, sodium polycarboxylate 9.5%, polydimethylsiloxane 0.3%, aqueous sodium silicate 8.5%, balance water.

[0074] The preparation method of the above-mentioned chemical polymer penetrating drilling wall protection fluid is the same as that in Example 1, and will not be repeated here.

[0075] Comparative Example 2

[0076] This comparative example provides a drilling wall protection fluid, which differs from Example 2 only in that sodium hydroxide is used instead of sodium bicarbonate. The specific composition is as follows:

[0077] 5.0% silica fume, 0.7% potassium aluminum sulfate, 2.8% sodium hydroxide, 4.0% calcium chloride, 0.5% plant gum, 10.0% sodium polyacrylate, 0.4% polydimethylsiloxane, 6.6% waterborne polyurethane, with the balance being water.

[0078] The preparation method of the above-mentioned chemical polymer penetrating drilling wall protection fluid is the same as that in Example 2, and will not be repeated here.

[0079] Comparative Example 3

[0080] This comparative example provides a drilling wall protection fluid, which differs from Example 3 only in that xanthan gum is used instead of plant gum. The specific composition is as follows:

[0081] 3.8% silica fume, 0.6% potassium aluminum sulfate, 4.2% sodium bicarbonate, 3.0% calcium chloride, 0.4% xanthan gum, 12.0% sodium polycarboxylate, 0.2% isooctyltriethoxysilane, 6.5% aqueous sodium silicate, with the balance being water.

[0082] The preparation method of the above-mentioned chemical polymer penetrating drilling wall protection fluid is the same as that in Example 3, and will not be repeated here.

[0083] Comparative Example 4

[0084] This comparative example provides a drilling wall protection fluid, which differs from Example 4 only in that sodium methylsilanolate is used instead of isooctyltriethoxysilane. The specific composition is as follows:

[0085] The composition is as follows: silica fume 6.8%, potassium aluminum sulfate 0.4%, sodium bicarbonate 5.8%, calcium chloride 3.3%, water-soluble sodium hydroxyethyl cellulose 0.3%, sodium polyacrylate 7.0%, sodium methylsilanol 0.2%, aqueous sodium silicate 7.2%, with the remainder being water.

[0086] The preparation method of the above-mentioned chemical polymer penetrating drilling wall protection fluid is the same as that in Example 4, and will not be repeated here.

[0087] Comparative Example 5

[0088] This comparative example provides a drilling wall protection fluid, which differs from Example 5 only in that it uses hydroxymethyl cellulose instead of water-soluble sodium hydroxyethyl cellulose. The specific composition is as follows:

[0089] 7.6% silica fume, 0.8% potassium aluminum sulfate, 5.2% sodium bicarbonate, 4.8% calcium chloride, 0.4% hydroxymethyl cellulose, 4% sodium polyacrylate, 5% sodium polycarboxylate, 0.3% polydimethylsiloxane, 8.1% aqueous sodium silicate, with the balance being water.

[0090] The preparation method of the above-mentioned chemical polymer penetrating drilling wall protection fluid is the same as that in Example 4, and will not be repeated here.

[0091] Performance testing

[0092] To demonstrate the effectiveness of the borehole wall protection fluids prepared in the embodiments and comparative examples of the present invention, the technical indicators of the borehole wall protection fluids in Examples 1-7 and Comparative Examples 1-5 were tested below. The specific test methods are as follows:

[0093] ① Relative density: Measured using a mud relative density meter.

[0094] ② Viscosity: Measured using a standard funnel viscometer.

[0095] ③ Sand content: Measured using a sand content meter.

[0096] ④ Colloid content: Place 100 mL of mud into a clean measuring cup, cover it with a glass plate, and let it stand for 24 hours. The mud at the top of the measuring cup may become clear water, while there may be sediment at the bottom. The colloid content is calculated as 100 - (water + sediment) / volume.

[0097] ⑤ pH value: pH meter.

[0098] ⑥ Water loss rate and mud cake thickness: Place a 120mm × 120mm filter paper on a horizontal glass plate and draw a 30mm diameter circle in the center. Drop 2mL of mud slurry into the center of the circle. After 30 minutes, measure the average radius of the wetted circle minus the average radius of the mud cake formed by the mud slurry (mm). This is the water loss. The calculated result (mm) represents the water loss. Measure the thickness of the mud cake (mm) on the filter paper; this is the mud cake thickness. The flatter and thinner the mud cake, the higher the quality of the mud slurry. Generally, it should not be thicker than 2-3mm.

[0099] According to Appendix K of the "Technical Specification for Construction of Highway Bridges and Culverts" (JTG / T 3650-2020), the test results of various performance indicators of the mud slurry for Examples 1-7 and Comparative Examples 1-5 are shown in Table 1.

[0100] Table 1

[0101]

[0102]

[0103] Among the key performance indicators of drilling wall protection fluid, a high-quality product should have: low sand content, low water loss rate, and flat and thin mud cake.

[0104] High sand content reduces viscosity, increases sedimentation, affects slag carrying capacity and borehole stability, easily wears down drilling tools, and can cause drill bit burial and stuck accidents.

[0105] A low water loss rate is beneficial for consolidating the borehole wall and protecting the bedrock, while a high water loss rate can lead to an excessively thick mud cake on the borehole wall, causing shrinkage or softening and expansion of the wall, resulting in borehole collapse. The lower the water loss rate, the higher its colloidal content. The thickness of the mud cake is directly proportional to the water loss rate.

[0106] As can be seen from the data in the table above, the performance indicators of the wall-protecting fluids in Examples 1-7 meet the relevant specifications. However, in Comparative Examples 1-5, when other substances were used to replace the components in this invention, the test results showed decreased viscosity and colloid content, increased sand content and water loss rate, and thicker mud cake, failing to meet the important performance indicators of the wall-protecting fluid slurry. This further demonstrates that each component in this invention is indispensable and irreplaceable. The colloidal system formed by their mutual reactions yields excellent technical performance indicators and can achieve ideal wall-protecting effects, which are unmatched by other physicochemical substances. The overall performance of the drilling wall-protecting fluid provided by the embodiments of this invention is significantly better than that of the comparative examples, indicating that the drilling wall-protecting fluid provided by the embodiments of this invention has a better wall-protecting function and can effectively avoid problems such as borehole wall collapse and difficulty in carrying rock cuttings during drilling. It has broad application prospects in pile foundation construction in fields such as construction and transportation.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A penetrating drilling wall protection fluid, characterized in that, The raw material components include the following percentages by weight: silica fume 2.0%–8.0%, potassium aluminum sulfate 0.3%–1.2%, sodium bicarbonate 2.5%–6.0%, calcium chloride 2.0%–5.2%, organic polymer 0.2%–0.6%, anionic surfactant 7.0%–15.0%, silane hydrophobic agent 0.1%–0.6%, gelling agent 5.0%–10.0%, and the balance being water; The organic polymer is one or both of plant gum or water-soluble sodium hydroxyethyl cellulose.

2. The penetrating drilling wall protection fluid as described in claim 1, characterized in that, The raw material components include the following percentages by weight: silica fume 3.8%–7.6%, potassium aluminum sulfate 0.4%–0.8%, sodium bicarbonate 2.8%–5.8%, calcium chloride 3.0%–4.8%, organic polymer 0.3%–0.5%, anionic surfactant 7.0%–12.0%, silane hydrophobic agent 0.2%–0.4%, gelling agent 6.5%–8.5%, and the balance being water.

3. The penetrating drilling wall protection fluid as described in claim 2, characterized in that, The raw material components include the following percentages by weight: silica fume 5.5%–7.6%, potassium aluminum sulfate 0.5%–0.8%, sodium bicarbonate 3.6%–5.8%, calcium chloride 3.8%–4.8%, organic polymer 0.3%–0.4%, anionic surfactant 9.0%–9.5%, silane hydrophobic agent 0.3%–0.4%, gelling agent 8.0%–8.5%, and the balance being water.

4. The penetrating drilling wall protection fluid according to any one of claims 1 to 3, characterized in that, The anionic surfactant is one or both of sodium polyacrylate or sodium polycarboxylate.

5. The penetrating drilling wall protection fluid according to any one of claims 1 to 3, characterized in that, The silane-based hydrophobic agent is one or both of polydimethylsiloxane or isooctyltriethoxysilane.

6. The penetrating drilling wall protection fluid according to any one of claims 1 to 3, characterized in that, The gelling agent is one or both of aqueous sodium silicate or aqueous polyurethane.

7. A method for preparing a penetrating borehole wall protection fluid, characterized in that, Includes the following steps: According to the design ratio of the permeable drilling wall protection fluid according to any one of claims 1 to 6, weigh each component, dissolve the weighed silica fume, potassium aluminum sulfate and calcium chloride in water, then add the weighed anionic surfactant and silane hydrophobic agent in sequence, mix evenly, add organic polymer, dissolve, add gel solidifying agent and sodium bicarbonate, mix evenly to obtain the permeable drilling wall protection fluid.

8. The application of the penetrating drilling wall protection fluid according to any one of claims 1 to 6 in pile foundation drilling construction.

Images