Slurry system suitable for complex rock stratum drilling and preparation method and application thereof
By optimizing the bentonite mud system and adding rock cuttings and specific polymers, the problems of large rock cuttings and unstable mud performance in drilling complex rock formations were solved, resulting in a reduction in filtration loss and viscosity, and improving drilling stability and efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANDI SCI & TECH CO LTD
- Filing Date
- 2025-12-30
- Publication Date
- 2026-05-12
AI Technical Summary
During drilling in complex rock formations, the large amount of rock debris and the high concentration of inferior solid phases in the drilling mud make it difficult to control rheology and filtration loss, resulting in low drilling efficiency, unstable wellbore, and accidents such as stuck drill and mud loss.
A bentonite slurry system was adopted, with the addition of rock slag, filtration loss reducer, coating inhibitor, and viscosity reducer. By optimizing the formula and static curing process, the pH value was adjusted to form a stable slurry system, which inhibited rock slag dispersion and filtration loss, and improved the rheological properties and wall protection performance of the slurry.
It significantly reduced mud loss and viscosity, improved mud cake quality, enhanced mud inhibition and wall protection properties, reduced stuck pipe and leakage accidents, and improved drilling efficiency.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of drilling technology. Specifically, it relates to a mud system suitable for drilling in complex rock formations, its preparation method, and its application. Background Technology
[0002] Because the Jurassic strata in western China contain a large amount of mudstone, which has a certain strength and hardness in its original state, it rapidly turns into mud upon contact with water after being broken by drill bits. Some well sections have extremely high mud-making capacity, causing the viscosity and specific gravity of the mud in the wellbore to increase rapidly, exceeding the values required for drilling and affecting drilling efficiency. Continuous viscosity reduction treatment is necessary. The conventional and most effective method is to drain the mud and dilute it with water, but current environmental regulations prevent direct discharge; solid-liquid separation is required. Sodium tripolyphosphate is used on-site as a viscosity reducer, which can lower mud viscosity for a certain period and mechanically reduce the solid phase. However, sodium tripolyphosphate causes fluctuations in other mud properties, and the mechanical solids control device has insufficient capacity to meet on-site construction requirements.
[0003] The geological formations drilled during construction in the Ordos region are complex and varied. Once the drill bit penetrates a formation, the surrounding soil loses its mechanical balance, leading to a variety of accidents such as borehole wall scattering, collapse, soil and rock accumulation, and borehole enlargement or reduction. When encountering highly hydrated clay or silt layers, excessively high mud viscosity or rapid drilling can cause mud buildup on the drill bit. Improper handling can result in stuck drill bit, preventing it from being lifted or rotated, or even completely jamming it, burying hundreds of meters of drilling equipment underground and rendering the project unusable. In highly porous formations, varying degrees of mud loss can occur.
[0004] Therefore, in the face of the problems of large amount of rock debris, high concentration of inferior solid phase intrusion in mud, and difficulty in controlling rheology, filtration loss and mud cake quality during vertical shaft drilling in the Ordos area, further research is still needed on the mud system for drilling in complex rock formations. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a mud system suitable for drilling large-diameter ultra-deep vertical shafts in water-rich and complex rock formations, along with its preparation method and application. This addresses the problems of large amounts of rock debris, high concentrations of inferior solid phases intruding into the mud, and difficulties in controlling rheological properties, filtration loss, and mud cake quality during existing drilling operations in complex rock formations.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:
[0007] A drilling mud system suitable for drilling in complex rock formations, consisting of bentonite mud and rock cuttings, with 23-41g of rock cuttings added per 100mL of bentonite mud; the bentonite mud is composed of the following raw materials in parts by weight: 1-8 parts bentonite, 0.03-0.32 parts sodium carbonate, 0.1-1 parts filtration loss reducer, 0.1-0.5 parts coating inhibitor, 0.10-0.15 parts viscosity reducer, and 100 parts water.
[0008] The above-mentioned mud system, suitable for drilling in complex rock formations, uses carboxymethyl cellulose and / or polyanionic cellulose as the filtration reducer; potassium polyacrylamide (KPAM) and / or zwitterionic polymer strong coating agent FA367 as the coating inhibitor; and viscosity reducer XY-27 and / or sodium tripolyphosphate as the viscosity reducer.
[0009] The above-mentioned mud systems are suitable for drilling in complex rock formations. Bentonite meets the requirements of GB / T 5005-2010; carboxymethyl cellulose and polyanionic cellulose meet the requirements of GB / T 5005-2010; potassium polyacrylamide (KPAM) meets the requirements of SY / T 5946-2019; and viscosity reducer XY-27 meets the requirements of SY / T 5695-2017.
[0010] The above-mentioned mud system is suitable for drilling in complex rock formations. The carboxymethyl cellulose is low-viscosity carboxymethyl cellulose CMC-LVT or high-viscosity carboxymethyl cellulose CMC-HVT; the polyanionic cellulose is low-viscosity polyanionic cellulose PAC-LV or high-viscosity polyanionic cellulose PAC-HV; the coating inhibitor is potassium polyacrylamide KPAM; and the viscosity reducer is viscosity reducer XY-27.
[0011] The above-mentioned mud system is suitable for drilling in complex rock formations. The rock cuttings are taken from rock fragments at a depth of 100-900m in the area to be drilled; the on-site density of the rock cuttings is 2.0-3.0 g / cm³. 3 Rock slag passed through a 100-mesh sieve.
[0012] The above-mentioned mud system is suitable for drilling in complex rock formations. The bentonite mud consists of the following raw materials in parts by weight: 3-5 parts bentonite, 0.1-0.2 parts sodium carbonate, 0.1-0.3 parts filtration loss reducer, 0.1 parts coating inhibitor, 0.1 parts viscosity reducer, and 100 parts water; the mass of sodium carbonate is 3wt%-4wt% of the mass of bentonite.
[0013] The above-mentioned mud system, suitable for drilling in complex rock formations, has a density of 1.15-1.23 g / cm³. 3 The water loss is less than or equal to 25 mL / 30 min, the mud cake thickness is less than or equal to 1.5 mm, the sand content is less than or equal to 2 wt%, and the pH is 7-8.
[0014] A method for preparing a mud system suitable for drilling in complex rock formations includes the following steps:
[0015] (1) Weigh each raw material component according to the proportion of the raw materials of the mud system and set aside; the raw materials of the mud system consist of bentonite mud and rock slag, and add 23-41g of rock slag for every 100mL of bentonite mud; the bentonite mud consists of the following raw materials in parts by weight: 1-8 parts of bentonite, 0.03-0.32 parts of sodium carbonate, 0.1-1 parts of filtration loss reducer, 0.1-0.5 parts of coating inhibitor, 0.10-0.15 parts of viscosity reducer and 100 parts of water;
[0016] (2) Mix and stir each raw material component evenly, and then let it stand for curing to obtain mixed mud; standing curing is beneficial to maintaining the chemical and physical stability of mud. During this process, the hydration of bentonite, the extension of polymer chains, and the completion of chemical reactions can be achieved.
[0017] (3) Add an alkaline solution to the mixed mud to adjust the pH to neutral or alkaline; thus, the mud system suitable for drilling in complex rock formations is obtained.
[0018] During the settling process, the chemical composition and solid content of the mud system may still be changing. If the pH is adjusted before settling, these changes may cause the adjusted pH value to deviate from the target range again. Furthermore, adding alkaline solution before settling can adversely affect the mud's performance. Adjusting the pH after settling is complete allows the physicochemical reactions of the mud system to be finished, resulting in a more stable system and a clearer pH adjustment target.
[0019] The above-mentioned method for preparing mud systems suitable for drilling in complex rock formations includes the following steps: in step (2), the mixing time is 20-30 min; the static curing time is 18-30 h; in step (3), the alkaline solution is a NaOH solution with a mass fraction of 5-15%; and the pH of the mud system is adjusted to 7-8.
[0020] An application of a mud system suitable for drilling in complex rock formations: the aforementioned mud system suitable for drilling in complex rock formations is used in the preparation of drilling fluids for drilling in complex rock formations, such as for the preparation of drilling fluids in the Ordos region.
[0021] The technical solution of the present invention achieves the following beneficial technical effects:
[0022] Due to the significant increase in viscosity of drilling mud after contamination by formation rock cuttings during drilling, it is necessary to improve the mud's ability to inhibit rock cuttings, reduce the dispersibility and water film thickness of rock cuttings in the mud, and minimize uncontrollable impacts on mud performance. This invention optimizes the bentonite polymer formulation by using high-quality bentonite slurry and a macromolecular-weight coated inhibition polymer, achieving a rock cutting weight of 1.15 g / cm³. 3Subsequently, when the polymer filtration loss reducer dosage was 0.1%, 0.2%, and 0.3%, the filtration loss decreased by 43.1%, 43.8%, and 44.5%, respectively; the apparent viscosity decreased by 32.3%, 25.8%, and 6.5%; and the mud cake thickness decreased from 2 mm to 0.5 mm, 0.5 mm, and 1.0 mm, respectively. Rock slag was used to increase the weight to 1.23 g / cm³. 3 Subsequently, when the polymer filtration loss reducer was added at concentrations of 0.1%, 0.2%, and 0.3%, the filtration loss decreased by 52.9%, 55.9%, and 56.6%, respectively; the apparent viscosity decreased by 31.6%, 13.2%, and 5.3%, respectively; and the mud cake thickness decreased from 2 mm to 0.5 mm, 1.0 mm, and 1.0 mm, respectively.
[0023] This invention utilizes KPAM (potassium polyacrylamide) to further enhance the inhibitory properties of bentonite polymer mud. After adding 0.1% KPAM, the weight was increased to 1.15 g / cm³ using rock slag. 3 The filtration loss of the bentonite polymer mud decreased from 15.8 mL to 14.8 mL, and the mud cake thickness was 0.5 mm; the weight of the mud cake was increased to 1.23 g / cm³ using rock slag. 3 The filtration loss of the bentonite polymer slurry decreased from 10.4 mL to 9.8 mL, and the mud cake thickness decreased from 1 mm to 0.5 mm.
[0024] The present invention uses 0.1% viscosity reducer to reduce mud viscosity, and the mud filtration loss is reduced at the same time. Moreover, its viscosity reducing ability is significantly higher than that of sodium tripolyphosphate, indicating that the preferred viscosity reducer can not only optimize the rheological properties of mud, but also improve the quality of mud cake and enhance the wall protection performance of mud. Detailed Implementation
[0025] To make the objectives, technical solutions, and technical effects of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0026] Raw materials used in the embodiments of this invention:
[0027] Core samples from 10 depths in the Xinjie Taigemiao mining area of Inner Mongolia were collected, and rock cuttings were prepared by passing through 6-10 mesh sieves and 100 mesh sieves, respectively, for later use. (During the experiment, it was found that rock cuttings passing through 100 mesh sieves had a significantly better effect on improving the performance of the mud system than those passing through 6-10 mesh sieves. Therefore, in this embodiment, rock cuttings passing through 100 mesh sieves were selected for the experiment.) The main components of rocks at different well depths are shown in Table 1, and the physicochemical properties of the rock cuttings are shown in Table 2.
[0028] Table 1. Main components of rocks at different well depths
[0029]
[0030] Table 2. Physicochemical properties of rock slag
[0031]
[0032] Table 2 shows that the bentonite equivalent of rocks in different strata ranges from 1.43 to 10.69 g / L, with rock fragments #1, #8, and #10 having higher bentonite equivalents. The water rolling recovery rate ranges from 9.24% to 89.42%, with rock fragments #1, #2, #5, and #10 having a rolling recovery rate of <30%, indicating strong dispersion. The 24-hour swelling rate ranges from 6.79% to 24.1%, with rock fragments #8 and #10 exceeding 10%, indicating strong swelling properties.
[0033] 1. The effect of bentonite addition on mud performance
[0034] To ensure that drilling mud possesses the necessary properties, the bentonite content in the mud must be controlled within a certain range. Insufficient bentonite content will result in suboptimal performance, while excessive bentonite content will cause the mud to lose its good rheological properties. This will lead to drill bit mud pocketing, excessive accumulation of rock cuttings in the mud, difficulty in operating solids control equipment, and excessively high pressure surge values that make pump start-up difficult or cause accidents such as sticking and formation leakage.
[0035] (1) Preparation of 8wt% bentonite mud
[0036] Add 11.2g of anhydrous sodium carbonate and 320g of bentonite to 4000mL of water using a low-speed stirrer. After stirring for 20 minutes, seal the container and let it stand for 24 hours to obtain an 8wt% bentonite slurry.
[0037] (2) Performance evaluation of bentonite slurry with different concentrations
[0038] After curing, 8 wt% bentonite slurry was mixed with different volumes of water and stirred thoroughly to prepare bentonite suspensions of 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, and 8 wt%. The pH of the bentonite suspensions was adjusted to 8 using a 10 wt% NaOH solution. The rheological properties, filtration loss, mud cake thickness, and mud cake adhesion coefficient of the bentonite suspensions were then measured.
[0039] Experimental results show that when the concentration of bentonite suspension is ≤2wt%, the low solid particle count results in low viscosity, zero shear stress, and high filtration loss. When the bentonite concentration is 3wt%-5wt%, viscosity and shear stress increase with increasing bentonite concentration, while filtration loss decreases significantly, resulting in a thin and dense mud cake with a low adhesion coefficient (<0.1). When the bentonite concentration in the suspension is ≥6wt%, the viscosity and shear stress of the bentonite suspension increase rapidly, and the rheological properties deteriorate. The optimal bentonite concentration for adding bentonite to mud is 3wt%-5wt%.
[0040] 2. The effect of the addition of rock cuttings and filtration loss reducers in the mud system on mud performance.
[0041] To maintain wellbore stability, a certain mud column pressure is needed to balance the formation pressure. Based on geological data from the Xinjie block in Inner Mongolia, the mud density needs to be increased to 1.15-1.23 g / cm³. 3 Therefore, an evaluation study was conducted on the properties of the mud after rock cuttings were introduced into the mud.
[0042] The density of the bentonite polymer mud (3 wt% bentonite addition) is 1.03 g / cm³. 3 The density of the rock debris at the site is approximately 2.4 g / cm³. 3 The mass of rock debris required to increase the density of the mud can be calculated using the following formula.
[0043] W b =VD b (D–D0) / (D b –D)
[0044] In the formula: W b =Mass of required weighting material, g; D b = Density of the weighting material, g / cm³ 3 V = Volume of mud before weighting, in cm³ 3 D = density of the mud after weighting, g / cm³ 3 D0 = density of the mud before weighting, g / cm³ 3 .
[0045] Calculations showed that increasing the weight of the bentonite polymer slurry (3 wt% bentonite) to 1.15 g / cm³ was effective. 3 and 1.23 g / cm 3 Rock slag of 23 g / 100 mL and 41 g / 100 mL needs to be added. To demonstrate the feasibility of adding rock slag powder for weighting, the following mud formulations were evaluated, and the experimental results are shown in Table 3.
[0046] Comparative Sample 1: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) with a mass-to-volume ratio of 23 g / 100 mL. 3 The mass-to-volume ratio is the ratio of the mass of rock slag to the total volume of the above raw materials.
[0047] Comparative Sample 2: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 41 g / 100 mL. 3 );
[0048] Formula 1#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 23 g / 100 mL. 3 );
[0049] Formula 2#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 23 g / 100 mL. 3 );
[0050] Formula 3#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 23 g / 100 mL. 3 );
[0051] Formula 4#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 41 g / 100 mL. 3 );
[0052] Formula 5#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 41 g / 100 mL. 3 );
[0053] Formula 6#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 41 g / 100 mL. 3 ).
[0054] The preparation method of this mud system includes the following steps:
[0055] (1) Weigh each component according to the raw material ratio and set aside;
[0056] (2) Mix all raw material components, stir for 20 minutes, and then let stand for 24 hours;
[0057] (3) Add NaOH solution to adjust the pH of the mud system to 8; and you get the mud.
[0058] Table 3. Properties of CMC-LV mud at different concentrations
[0059] In Table 3, the commonly used unit for YP (dynamic shear force) is Pascal (Pa). In drilling operations, the dynamic shear force (YP) of non-weighted drilling fluids is typically maintained between 1.4 and 14.4 Pa to balance cuttings suspension and wellbore cleaning requirements. According to Table 3, compared to bentonite mud, using cuttings weighted to 1.15 g / cm³... 3 Subsequently, when the polymer filtration loss reducer was added at dosages of 0.1wt%, 0.2wt%, and 0.3wt%, the filtration loss decreased by 43.1%, 43.8%, and 44.5%, respectively; the apparent viscosity decreased by 32.3%, 25.8%, and 6.5%; and the mud cake thickness decreased from 2 mm to 0.5 mm, 0.5 mm, and 1.0 mm, respectively. Rock slag was used to increase the weight to 1.23 g / cm³. 3 Subsequently, when the polymeric filtration loss reducer was added at concentrations of 0.1 wt%, 0.2 wt%, and 0.3 wt%, the filtration loss decreased by 52.9%, 55.9%, and 56.6%, respectively; the apparent viscosity decreased by 31.6%, 13.2%, and 5.3%, respectively; and the mud cake thickness decreased from 2 mm to 0.5 mm, 1.0 mm, and 1.0 mm, respectively. The polymeric filtration loss reducer dosage refers to the mass percentage of the polymeric filtration loss reducer relative to the water in the feedstock.
[0060] 3. The effect of adding coating inhibitors to the mud system on mud performance.
[0061] In shallow formation mud, polymers are commonly used as coating inhibitors, with FA367 and KPAM (potassium polyacrylamide) being frequently used. Experimental data shows that insufficient FA367 leads to a thicker mud cake, increasing its compressibility; when the FA367 dosage exceeds 0.45 wt%, the mud cake becomes thin and dense. Conversely, a small amount of KPAM improves mud cake quality; the larger the dosage, the thinner and denser the mud cake, thus reducing its compressibility. This result is explained by KPAM's ability to provide electrolytes, further enhancing the mud's liquid-phase inhibition ability by increasing liquid-phase cohesion. This demonstrates that different polymers do indeed exhibit different mud cake compression characteristics, reflecting the special significance of functional groups in molecular design.
[0062] Analysis of the physicochemical properties of the formation rocks showed that rock cuttings #8 and #10 had high expansibility, while rock cuttings #1, #2, #5, and #10 had strong dispersibility. Therefore, highly efficient inhibitors need to be added to improve the mud's inhibition effect on the formation rocks and its wall-protecting ability, maintaining wellbore stability. Potassium polyacrylamide (KPAM) is a polyelectrolyte with long hydrophobic molecular chains and highly inhibitory K+. When added to water-based mud, it can simultaneously inhibit permeation hydration, enhance cohesion, and reduce the internal driving force of filtrate intrusion into the formation. This example analyzes the rheological properties, plugging properties, and inhibition properties of the following KPAM mud formulations to improve mud inhibition; the results are shown in Table 4.
[0063] Comparative Sample 1: The mud system consists of the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT) and 100 parts water;
[0064] Comparative Sample 2: The mud system consists of the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT) and 100 parts water;
[0065] Comparative Sample 3: The mud system consists of the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT) and 100 parts water;
[0066] Comparative Sample 4: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 10 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 23 g / 100 mL. 3 );
[0067] Comparative Sample 5: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low-viscosity carboxymethyl cellulose CMC-LVT), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 10 rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 41 g / 100 mL. 3 );
[0068] Formula 1#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts coating inhibitor (KPAM), and 100 parts water;
[0069] Formula 2#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.3 parts coating inhibitor (KPAM), and 100 parts water;
[0070] Formula 3#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.5 parts coating inhibitor (KPAM), and 100 parts water;
[0071] Formula 4#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts coating inhibitor (KPAM), and 100 parts water;
[0072] Formula 5#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.3 parts coating inhibitor (KPAM), and 100 parts water;
[0073] Formula 6#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.5 parts coating inhibitor (KPAM), and 100 parts water;
[0074] Formula 7#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts coating inhibitor (KPAM), and 100 parts water;
[0075] Formula 8#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.3 parts coating inhibitor (KPAM), and 100 parts water;
[0076] Formula 9#: The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.5 parts coating inhibitor (KPAM), and 100 parts water;
[0077] Formula 10#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT), 0.1 parts coating inhibitor (KPAM), and 100 parts water. Based on the total volume of the above raw materials, it also includes 10# rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 23 g / 100 mL. 3 );
[0078] Formula 11#: The mud system comprises the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT), 0.1 parts coating inhibitor (KPAM), and 100 parts water. Based on the total volume of the above raw materials, it also includes 10# rock slag (passed through 100 mesh; on-site density 2.4 g / cm³) at a mass-to-volume ratio of 41 g / 100 mL. 3 );
[0079] Table 4 Comparison of mud properties before and after adding KPAM
[0080] Table 4 shows that adding KPAM to bentonite polymer mud can further reduce the filtrate loss of the mud and significantly reduce the mud cake thickness of the rock-weighted mud. Comparing the effects of KPAM dosage on the performance of bentonite polymer mud, it is recommended that adding 0.1 wt% KPAM is sufficient to achieve the effect of toughening the mud cake and improving the plugging effect. Further increasing the concentration will result in a rapid increase in viscosity and a weakening effect in reducing filtrate loss.
[0081] 4. The effect of adding viscosity reducers to the mud system on mud performance.
[0082] As the rock cuttings content increases, the viscosity of the drilling mud also increases, leading to a deterioration in mud cake quality and an increase in the coefficient of friction. This not only increases resistance during tripping and drilling but can also cause complex issues such as mud buildup on the drill bit and drill bit diameter reduction. Therefore, it is necessary to reduce the mud viscosity, inhibit rock cuttings dispersion, and restore the mud's good rheological properties. Using solids control equipment to reduce the rock cuttings content is the first recommended measure for optimizing mud rheology. In addition to fully utilizing the solids control equipment, adding viscosity reducers is an effective way to adjust mud rheology. This example evaluates the viscosity-reducing effect of the following high-concentration rock cuttings formulations and compares the viscosity-reducing effects of no viscosity reducer, adding viscosity reducer XY-27, and adding sodium tripolyphosphate. The results are shown in Table 5.
[0083] Formula 1#:
[0084] ①The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 40g / 100mL.
[0085] ②The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts viscosity reducer (XY-27) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 40g / 100mL.
[0086] ③ The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts viscosity reducer (sodium tripolyphosphate) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 40g / 100mL.
[0087] Formula 2#:
[0088] ①The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 41g / 100mL.
[0089] ② The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts viscosity reducer (XY-27), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 41g / 100mL.
[0090] ③ The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts viscosity reducer (sodium tripolyphosphate), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 41g / 100mL.
[0091] Formula 3#:
[0092] ①The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 41g / 100mL.
[0093] ② The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts viscosity reducer (XY-27), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 41g / 100mL.
[0094] ③ The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts viscosity reducer (sodium tripolyphosphate), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 41 g / 100 mL.
[0095] Formula 4#:
[0096] ① The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts coating inhibitor (KPAM), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0097] ② The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts viscosity reducer (XY-27), 0.1 parts coating inhibitor (KPAM), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30 g / 100 mL.
[0098] ③ The mud system includes the following raw materials by weight: 3 parts bentonite, 0.105 parts sodium carbonate, 0.1 parts filtration loss reducer (low viscosity carboxymethyl cellulose CMC-LVT), 0.1 parts viscosity reducer (sodium tripolyphosphate), 0.1 parts coating inhibitor (KPAM), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30 g / 100 mL.
[0099] Formula 5#:
[0100] ①The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0101] ② The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT), 0.1 parts viscosity reducer (XY-27), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0102] ③ The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.2 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT), 0.1 parts viscosity reducer (sodium tripolyphosphate), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0103] Formula 6#:
[0104] ①The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0105] ② The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT), 0.1 parts viscosity reducer (XY-27), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0106] ③ The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (high viscosity carboxymethyl cellulose CMC-HVT), 0.1 parts viscosity reducer (sodium tripolyphosphate), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0107] Formula 7#:
[0108] ①The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (high viscosity polyanionic cellulose PAC-HV) and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0109] ② The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (high viscosity polyanionic cellulose PAC-HV), 0.1 parts viscosity reducer (XY-27), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0110] ③ The mud system includes the following raw materials by weight: 2 parts bentonite, 0.105 parts sodium carbonate, 0.3 parts filtration loss reducer (high viscosity polyanionic cellulose PAC-HV), 0.1 parts viscosity reducer (sodium tripolyphosphate), and 100 parts water. Based on the total volume of the above raw materials, it also includes No. 9 rock slag (passed through 100 mesh) with a mass-volume ratio of 30g / 100mL.
[0111] Table 5 Comparison of viscosity reduction performance of different mud formulations before and after.
[0112] The weight was increased to 1.15 g / cm³ using rock slag. 3 Afterwards, the mud's properties met drilling requirements. Rock cuttings were added to increase the weight to 1.23 g / cm³. 3 Subsequently, if the viscosity is too high, a viscosity reducer is needed to adjust the rheological properties of the mud. Table 5 shows that adding only 0.1 wt% of viscosity reducer XY-27 (to the mass percentage of the viscosity reducer to the water in the raw material) can reduce the viscosity of high-concentration rock slag mud by 12.8%-54.5%, and the higher the initial viscosity of the mud, the greater the reduction. While reducing viscosity, XY-27 can also simultaneously reduce the filtrate loss of the mud by 7.0%-36.5%. This is because XY-27 can selectively flocculate inferior clay, reducing the concentration of coarse and undispersed particles, making the mud cake denser. Sodium tripolyphosphate of the same concentration reduces the apparent viscosity of mud with the same formulation by 2.0-35.3%, and the filtrate loss by 0-28.4%.
[0113] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.
Claims
1. A mud system suitable for drilling in complex rock formations, characterized in that, It consists of bentonite mud and rock slag, with 23-41g of rock slag added per 100mL of bentonite mud; the bentonite mud is composed of the following raw materials in parts by weight: 1-8 parts bentonite, 0.03-0.32 parts sodium carbonate, 0.1-1 parts filtration loss reducer, 0.1-0.5 parts coating inhibitor, 0.10-0.15 parts viscosity reducer and 100 parts water.
2. The mud system suitable for drilling in complex rock formations according to claim 1, characterized in that, The filtration loss reducer is carboxymethyl cellulose and / or polyanionic cellulose; the coating inhibitor is potassium polyacrylamide (KPAM) and / or zwitterionic polymer strong coating agent FA367; the viscosity reducer is viscosity reducer XY-27 and / or sodium tripolyphosphate.
3. The mud system suitable for drilling in complex rock formations according to claim 2, characterized in that, Bentonite meets the requirements of GB / T 5005-2010; carboxymethyl cellulose and polyanionic cellulose meet the requirements of GB / T 5005-2010; potassium polyacrylamide (KPAM) meets the requirements of SY / T 5946-2019; and viscosity reducer XY-27 meets the requirements of SY / T5695-2017.
4. The mud system suitable for drilling in complex rock formations according to claim 3, characterized in that, Carboxymethyl cellulose is either low-viscosity carboxymethyl cellulose (CMC-LVT) or high-viscosity carboxymethyl cellulose (CMC-HVT); polyanionic cellulose is either low-viscosity polyanionic cellulose (PAC-LV) or high-viscosity polyanionic cellulose (PAC-HV); the coating inhibitor is potassium polyacrylamide (KPAM); and the viscosity reducer is viscosity reducer XY-27.
5. The mud system for drilling in complex rock formations according to claim 1, characterized in that, The rock cuttings are taken from rock cuttings at a depth of 100-900m in the area to be drilled; the on-site density of the rock cuttings is 2.0-3.0g / cm3; the rock cuttings pass through a 100-mesh sieve.
6. The mud system for drilling in complex rock formations according to claim 1, characterized in that, The bentonite slurry is composed of the following raw materials in parts by weight: 3-5 parts bentonite, 0.1-0.2 parts sodium carbonate, 0.1-0.3 parts filtration loss reducer, 0.1 parts coating inhibitor, 0.1 parts viscosity reducer, and 100 parts water; the mass of sodium carbonate is 3wt%-4wt% of the mass of bentonite.
7. The mud system for drilling in complex rock formations according to claim 1, characterized in that, The density is 1.15-1.23 g / cm3, the water loss is less than or equal to 25 mL / 30 min, the mud cake thickness is less than or equal to 1.5 mm, the sand content is less than or equal to 2 wt%, and the pH is 7-8.
8. A method for preparing a mud system suitable for drilling in complex rock formations, characterized in that, Includes the following steps: (1) Weigh each raw material component according to the proportion of the raw materials of the mud system and set aside; the raw materials of the mud system consist of bentonite mud and rock slag, and add 23-41g of rock slag for every 100mL of bentonite mud; the bentonite mud consists of the following raw materials in parts by weight: 1-8 parts of bentonite, 0.03-0.32 parts of sodium carbonate, 0.1-1 parts of filtration loss reducer, 0.1-0.5 parts of coating inhibitor, 0.10-0.15 parts of viscosity reducer and 100 parts of water; (2) Mix all raw material components evenly, and then let them stand for curing to obtain mixed mud; (3) Add an alkaline solution to the mixed mud to adjust the pH to neutral or alkaline; thus, a mud system suitable for drilling in complex rock formations as described in any one of claims 1-7 is obtained.
9. The method for preparing a mud system suitable for drilling in complex rock formations according to claim 8, characterized in that, In step (2), the mixing time is 20-30 min; the static curing time is 18-30 h; in step (3), the alkaline solution is a NaOH solution with a mass fraction of 5-15%; the pH of the mud system is adjusted to 7-8.
10. An application of a mud system suitable for drilling in complex rock formations, characterized in that, The mud system as described in any one of claims 1-7, suitable for drilling in complex rock formations, is used to prepare drilling fluid for the Ordos region.