Offshore wind power rock-socketed high-clay mud as well as preparation and application thereof

Abstract

The invention provides offshore wind power rock-socketed high-clay slurry and preparation and application thereof. The offshore wind power rock-socketed high-clay slurry is prepared by taking high-viscosity undisturbed soil with Ip greater than 25 as a framework, doping 0.08% of CMC-Na and 0.2% of Na2CO3, and mixing drilling cuttings with the density of 1.18-1.22 g / cm < 3 >, the funnel viscosity of 50-60 s, high dynamic shearing force and suspensible large particle size; the API water loss is less than 8mL / 30min, CMC-Na and clay are subjected to ion exchange to instantly form a compact mud cake on a pore wall, and high-pressure-bearing water is effectively isolated; the high-yield and strong-thixotropic gel can resist liquid level instantaneous pressure loss caused by tides and stormy waves, prevent hole shrinkage and hole collapse and guarantee deep sea hole forming stability and pile forming quality, has the characteristics of low solid phase, low filtration loss, high slag carrying capacity and excellent wall protection, is simple in formula, environment-friendly and economical, and is suitable for offshore wind power rock-socketed construction. The formula is simple, environment-friendly and economical, meets the requirements of offshore wind power rock-socketed construction, and has good popularization value.

Description

TECHNICAL FIELD

[0001] The present application relates to the offshore wind power foundation construction technical field, especially to a kind of offshore wind power rock-socketed high clay slurry and its preparation method and application. BACKGROUND

[0002] In offshore wind power rock-socketed pile construction, high clay layer brings great challenge to drilling construction due to its high plasticity, strong expansibility and low permeability. The traditional bentonite slurry often has the following problems in such stratum: Insufficient slurry viscosity and poor cuttings carrying capacity; Large filter loss and poor hole wall stability; Poor clay dispersibility, easy to form "mud ball drill"; Frequent hole wall shrinkage, sticking and hole collapse.

[0003] The existing technology relies on high bentonite content or multiple chemical additives, which is high in cost, complex in preparation and poor in environmental protection.

[0004] Therefore, there is an urgent need for a slurry system with simple formula, excellent performance and adaptation to high clay layer. SUMMARY

[0005] To solve the technical problems existing in the prior art, the present application provides the following technical solutions: On the one hand, a kind of offshore wind power rock-socketed high clay slurry is provided, characterized in that the slurry comprises the following components in mass percentage: 99.65% to 99.75% of high clay, 0.05% to 0.10% of CMC-Na and 0.15% to 0.25% of Na2CO3.

[0006] Preferably, the funnel viscosity of the slurry is 50 to 60 s, the API filter loss is ≤8 mL / 30 min, the pH value is 9 to 10.5, and the density is 1.08 to 1.18 g / cm 3 .

[0007] Preferably, the high clay is natural clay or marine sediment clay, with plasticity index ≥25 and clay content ≥40%.

[0008] Preferably, the CMC-Na is low-viscosity carboxymethyl cellulose sodium, with purity ≥90% and substitution degree 0.7 to 0.9.

[0009] Preferably, the Na2CO3 is industrial grade anhydrous sodium carbonate, with particle size ≤0.15 mm.

[0010] On the other hand, a preparation method of offshore wind power rock-socketed high clay slurry is provided, comprising the following steps: (1) Mix the high-cohesion soil with Na2CO3 and stir at high speed for 5-10 minutes to complete the sodium dispersion; (2) Slowly add CMC-Na to the mixture obtained in step (1) and continue stirring for 20 to 30 minutes until completely dissolved; (3) Let stand for 30-60 minutes to mature, controlling the density to 1.08-1.18 g / cm³. 3 That's it.

[0011] Preferably, the high-speed stirring speed in step (1) is 800-1200 r / min.

[0012] On the other hand, it provides an application of offshore wind power embedded rock high clay mud in the drilling construction of offshore wind power embedded rock piles.

[0013] Preferably, the application is suitable for highly cohesive soil layers with a plasticity index > 25, and is used for wall protection, slag carrying, and preventing hole collapse.

[0014] Preferably, the mud slurry level is maintained at 1.5 to 2.0 m above the highest tidal water level during construction.

[0015] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: This scheme maintains a relatively stable Na2CO3 dosage while precisely controlling the mud viscosity by fine-tuning the CMC-Na content. High-cohesive soil and CMC-Na are inversely complementary, ensuring the overall system remains stable. Experiments have confirmed that all three formulations meet the following requirements: funnel viscosity 50–60 s, API filtration loss ≤8 mL, pH 9–10.5, and density 1.08–1.18 g / cm³. -3 Within the range, the filtration loss further decreases with increasing CMC-Na. Overall, the experimental (median) performance is the most balanced and can be directly used as the first choice for field formulation; if encountering different strata, only a small adjustment of CMC-Na within the range of 0.02% to 0.03% is needed to quickly adapt while maintaining the original characteristics, thus balancing technical reliability and construction flexibility.

[0016] Based on the above applications, the present invention has the following advantages: The formula is extremely simple, with only three components, and it is easy to prepare on-site. It has excellent performance, moderate viscosity, low filtration loss, and strong slag carrying capacity. It is suitable for high-cohesion soil layers and effectively prevents diameter reduction and hole collapse; Environmentally friendly and economical, reducing reliance on transporting bentonite from overseas. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram illustrating the synergistic effect mechanism of mud mix proportions of a high-clay mud slurry embedded in rock for offshore wind power, provided in an embodiment of the present invention. Figure 2 This is an ultrasonic testing diagram of the quality of hole formation in the field provided by an embodiment of the present invention; Figure 3 This is a comparison image of traditional mud wall protection hole formation scanning provided by an embodiment of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0020] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0021] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning.

[0022] In this embodiment of the invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0023] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0024] This invention provides an offshore wind power embedded rock high-clay mud and its preparation and application. The mud is composed of the following components: high-clay soil: 99.65% to 99.75%, CMC-Na: 0.05% to 0.10%, Na2CO3: 0.15% to 0.25%, where the percentages are by mass.

[0025] like Figure 1 The diagram shown illustrates the synergistic mechanism of mud mix components in offshore wind power embedded rock high-clay mud. (The diagram includes the following information:) 1. High-cohesion soil: dual function of framework and activity The high-cohesion soil is natural clay or marine sedimentary clay with a plasticity index ≥25 and a clay content ≥40%. High-cohesion soil: sourced locally, it serves as the main solid phase, providing basic viscosity and shear strength.

[0026] High-cohesion soil has a high water absorption and swelling property. It first establishes a three-dimensional network in water, providing yield value and gel strength, and can buffer the impact of tides on the drilling tool. The negative charges on the edges of soil particles together form active anchor points, which lay the foundation for subsequent Na2CO3 sodium replacement and CMC-Na electrostatic adsorption, realizing the synergistic enhancement of dispersion, calcium sealing and filtration reduction.

[0027] 2. Na₂CO₃: Sodiumization – Dual chemical blockade of calcium and magnesium The Na2CO3 is industrial-grade anhydrous sodium carbonate, used for alkalizing and dispersing highly viscous soil to increase the colloid content of the mud. Na2CO3 (0.2%): alkalizes and disperses, increases colloid content, and prevents clay agglomeration.

[0028] First, add soda ash to replace the "hard calcium" in the clay with "soft sodium". The layers expand instantly, the soil particles disperse and become slippery, and the mud becomes "thick but not stiff" immediately, allowing rock debris to be moved. At the same time, the calcium and magnesium ions in the seawater are converted into fine lime particles, which are blocked in the pores of the mud skin. The water is filtered out and then reduced, resulting in a thin and tough mud skin.

[0029] 3. CMC-Na: Wall building and toughening The CMC-Na is a low-viscosity sodium carboxymethyl cellulose with a purity ≥90% and a degree of substitution of 0.7–0.9. CMC-Na (0.08%): increases viscosity, reduces filtration loss, and forms a dense mud cake.

[0030] With a degree of carboxymethyl substitution of 0.7–0.9, it undergoes electrostatic dual adsorption with the clay layer to form a "clay-polymer" nanocomposite film.

[0031] When preparing the solution on-site, first add Na2CO3 to the highly cohesive soil and stir for 5-10 minutes to complete the sodiumization. Then, slowly add 0.08% CMC-Na to prevent clumping. If there is a large tidal difference, the density can be adjusted from 1.12 t / m³. 3 Fine-tuned to 1.15t / m 3Without sacrificing fluidity, CMC-Na is a readily biodegradable polymer, and this concentration meets IMO emission standards, allowing for direct discharge or recycling. In summary, this formulation, through the synergistic effect of "high-viscosity soil framework + Na2CO3 sodiumization - calcium and magnesium sealing + CMC-Na filtration reduction - wall building," forms a thin, tough mud cake, low filtration loss, and high gel strength mud system in complex marine strata. This effectively resists tidal fluctuations, calcium and magnesium erosion, and formation hydration, ensuring long-term stability of the borehole wall for large-diameter, deep boreholes. The mud prepared by the above method meets the following process performance conditions: the mud funnel viscosity is 50–60 s, API filtration loss is ≤8 mL, pH value is 9–10.5, and density is 1.08–1.18 g / cm³. 3 .

[0032] Example 1: The following formula is prepared according to the proportions shown in Table 1: Table 1---Mud Preparation The implementation steps are as follows: When using high-cohesion soil as a slurry wall protection material, its "original soil sand content" should be controlled at ≤4%, with a limit not exceeding 6%, and the high-cohesion soil should be poured into the casing. Add Na2CO3 according to the formula ratio, stir at high speed for 10 minutes to alkalize and disperse; Slowly add CMC-Na and continue stirring for 20 minutes until completely dissolved; Let it stand and mature for 30 minutes before use.

[0033] The performance test results are shown in Table 2 below: Table 2 -- Performance Test Results Based on the above preparation steps, through variable control experiments of the proportions of the components, it can be found that the performance improvement data of sequentially adding CMC-Na and Na2CO3 to high-cohesive soil are shown in Table 3 below: Table 3 -- Variable Control Performance Test Results Example 2: A comparative experiment was conducted with traditional bentonite slurry (purchased from XX company), and the performance results are shown in Table 4 below: Table 4---Comparison of Filtration Loss between the Mud Slurry of the Present Invention and Conventional Bentonite Mud Slurry Example 3: Field Application Experiment In the construction of rock-socketed piles for the Pinghai Bay offshore wind power project in xx and Fangchenggang offshore wind power projects in Guangxi, the mud mix ratio of this invention was adopted. During the drilling process into high-cohesion soil layers (plasticity index = 32), it was combined with, as shown in the following... Figure 2The ultrasonic testing results of the borehole formation shown in the image reveal the following construction conditions: No diameter reduction or hole collapse; The thickness of sediment at the bottom of the borehole is less than 2 cm; Drilling efficiency increased by 30%.

[0034] For example Figure 3 The images shown are a comparison of traditional mud wall forming and borehole scanning. It can be observed that the borehole wall signal from traditional mud resembles a twisted "braid," with varying thicknesses of mud skin, localized V-shaped gaps from broken pieces, and a 1.2° deviation in verticality, requiring intermediate repairs. In contrast, the borehole wall echo from the new formula of this invention forms a smooth, bright band, demonstrating excellent performance in on-site ultrasonic borehole scanning. Figure 1 The hole is characterized by its uniform mud layer of only 1–2 mm, no abrupt reflections, verticality lock-in ≤0.3°, one-time drilling to the bottom, zero jamming of the drill bit, automatic movement of sediment, no collapse of the hole opening even after long periods of drilling stoppage, and stable hole wall.

[0035] Therefore, the mud mix ratio of high-cohesive soil + 0.08% CMC-Na + 0.2% Na2CO3 provided by this invention has a very simple formula, excellent performance, and is economical and environmentally friendly. It is particularly suitable for drilling construction of offshore wind power embedded rock piles in high-cohesive soil layers and has good prospects for promotion. It is applicable to drilling construction of offshore wind power embedded rock piles using high-cohesive soil mud mix ratio, and has the functions of wall protection, cuttings carrying, lubrication, and anti-collapse.

[0036] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A type of high-clay mud embedded in rock for offshore wind power, characterized in that, The mud comprises the following components by mass percentage: High cohesive soil 99.65%–99.75%, CMC-Na 0.05%–0.10%, and Na2CO3 0.15%–0.25%.

2. The offshore wind power embedded rock high-clay mud according to claim 1, characterized in that, The slurry has a funnel viscosity of 50–60 s, an API filtration loss of ≤8 mL / 30 min, a pH of 9–10.5, and a density of 1.08–1.18 g / cm³. 3 .

3. The offshore wind power embedded rock high-clay mud according to claim 1, characterized in that, The high-cohesion soil is natural clay or marine sedimentary clay with a plasticity index ≥25 and a clay content ≥40%.

4. The offshore wind power embedded rock high-clay mud according to claim 1, characterized in that, The CMC-Na is a low-viscosity sodium carboxymethyl cellulose with a purity ≥90% and a degree of substitution of 0.7 to 0.

9.

5. The offshore wind power embedded rock high-clay mud according to claim 4, characterized in that, The Na2CO3 is industrial-grade anhydrous sodium carbonate with a particle size ≤0.15mm.

6. A method for preparing offshore wind power embedded high-clay mud as described in any one of claims 1-5, characterized in that, The method includes the following steps: (1) Mix the high-cohesion soil with Na2CO3 and stir at high speed for 5-10 minutes to complete the sodium dispersion; (2) Slowly add CMC-Na to the mixture obtained in step (1) and continue stirring for 20 to 30 minutes until completely dissolved; (3) Let stand for 30-60 minutes to mature, controlling the density to 1.08-1.18 g / cm³. 3 That's it.

7. The preparation method according to claim 6, characterized in that, In step (1), the speed of high-speed stirring is 800-1200 r / min.

8. The application of the offshore wind power embedded rock high clay mud as described in any one of claims 1-5, or the offshore wind power embedded rock high clay mud prepared by the preparation method described in claim 6 or 7, in the drilling construction of offshore wind power embedded rock piles.

9. The application according to claim 8, characterized in that, The application is suitable for highly cohesive soil layers with a plasticity index > 25, and is used for wall protection, spoil carrying, and preventing hole collapse.

10. The application according to claim 8, characterized in that, During construction, the mud level should be maintained at 1.5 to 2.0 meters above the highest tidal water level.

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