Plastic Viscosity Research Articles

Low-ECD Inverted Emulsion Fluid Shows Superior Performance

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211539, “New Low-ECD Organophilic Clay-Free Inverted Emulsion Fluid Weighted With Manganese Tetroxide Showed Superior Performance in Different Fields: Success Story of Drilling With OCIEF in High-Overbalance Environment Without Downhole Problems, Stuck-Pipe Events, and Nonproductive Time,” by Vikrant Wagle, SPE, Abdullah Yami, SPE, and Abdullah Al Moajil, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ The complete paper describes the success of using a new low-equivalent-circulating-density (ECD) organophilic clay-free inverted emulsion fluid (OCIEF) in gas reservoirs at elevated temperatures and with differential pressures up to 4,500 psi. The objective of the paper is to highlight the superior performance of OCIEF over barite-based conventional invert-emulsion drilling fluids and formate-based, water-based drilling fluids in the study. The fluid overcame challenges in such an environment without compromising performance. Introduction The new low-ECD OCIEF, using manganese tetroxide as the weighting agent, was developed with an aim to offer improved drilling performance in maturing fields. Its nondamaging nature, the result of the presence of the acid-soluble and micronized manganese tetroxide, would help to complete the well with an openhole design. In an OCIEF, the organophilic clay and organophilic lignite are replaced by a polymeric viscosifier and a polymeric filtration-control agent, respectively. A unique gel structure is provided by the use of the polymeric viscosifier in the oil-based drilling fluid. Also, it not only increases cuttings-carrying capacity but also helps to increase barite sag resistance in the fluid. In the absence of low-gravity solids in terms of organoclay and organolignite, an OCIEF shows low plastic viscosity and a higher rate of penetration compared with conventional organoclay-based oil-based muds. In the OCIEF described in the paper, the solids content has been further reduced by replacing the barite (4.2 SG) with manganese tetroxide (4.8 SG). The acid solubility of manganese tetroxide would make the drilling fluid nondamaging, especially for reservoir zones. Formulation of Low-ECD OCIEF. The OCIEF was designed for long lateral sections where low rates of penetration (ROPs) can be observed in a slimhole drilling environment with a bottomhole temperature (BHT) of approximately 300°F. The OCIEF was tested for drilling in high-static overbalance conditions (3,000–4,500 psi) and had to be resistant to potential contaminants. The OCIEF was formulated with the acid-soluble manganese tetroxide with a water-phase salinity of 200,000–250,000 ppm. Two 95-lbm/ft3 OCIEFs were formulated. The 95-lbm/ft3 OCIEF 1 was developed with an engineered bridging package of variously sized ground marbles. This formulation was specifically for short laterals and lower differential pressures. The acid solubility of the ground-marble-based package was an additional benefit of the OCIEF 1 fluid formulation. An alternate, OCIEF 2, was developed for longer intervals with higher overbalance conditions. OCIEF 2 was formulated with a bridging package that included sized resilient graphite, fibers, and sized ground marble. The bridging package was designed for longer laterals because it was expected that the bridging solids would undergo increased mechanical attrition. A single polymeric filtration-control additive was used in both formulations.

Bentonite-Based Drilling Boyolali Mud Fabrication with Additive Carboxymethyl Cellulose, Na2CO3 and KOH

This study aimed to examine the effect of adding KOH, Na2CO3, and Carboxymethyl Cellulose additives on the physical properties of the mud, as well as the optimal additive for sludge production. The preparation of the basal sludge involved the addition of 22.5 grams of bentonite, 350 millilitres of distilled water, and 10 grams of Barite as a constant variable. Then it stated 0.5 variations of the Na2CO3 additive; 1.5; 3 grams, KOH 0.5; 1.5; and 3 grams, and Carboxymethyl Cellulose 3; 6; and 9 grams. A physical property measurement involving density was conducted. Samples were evaluated for Plastic Viscosity and Yield Point at 300 and 600 rpm dial speeds. After 30 minutes of filter press compression, the filtration loss, mud cake, and pH were measured. The results indicate that the KOH additive decreases Yield Point by 8.6 lb/100ft2 and increases Filtrate Loss by 5.8 mL and sediment pH by 11.12 points. The additive Na2CO3 then causes a reduction in Filtrate Loss of 10.4, 8.8, 7.6 mL and an increase in Plastic Viscosity. While Carboxymethyl Cellulose can increase Plastic Viscosity by 7; 13; 55 cP, Gel strength by 4; 6; 40 Lb/100 ft2, and Filtrate Loss by 10; 8; 7.6mL. Carboxymethyl Cellulose is the additive that has the most significant effect on the physical properties of the mud because it can affect Plastic Viscosity, Gel Strength, Yield Point, and Filtrate Loss so that the soil can approach API 13A Standards. The optimal amount of Carboxymethyl Cellulose should be added at a mass of 6 grams, or 13 cP.

​​Synthesis of graphene oxide using modified hammers method as fluid loss control additive for water-based drilling fluid (WBDF)​

Water-based drilling fluid (WBDF) is one of the commonly used fluids in drilling operations due to its low cost and environmental advantages compared to oil-based fluid (OBF) and synthetic-based fluid (SBF). The effectiveness of a drilling fluid is mainly dependent on its rheological and filtration properties and these properties are strongly correlated to the type of additives used during the formulation of drilling mud. This study aims to investigate the use of graphene oxide (GO) as a nano-additive in WBDF and evaluate its influence on the rheology and filtration properties of the drilling fluid. Basic rheological properties such as plastic viscosity, yield point, filter cake thickness and density were examined. GO was synthesised using modified Hummer’s method and characterised using x-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyser (TGA) and scanning electron microscope (SEM) to confirm the properties of GO. XRD analysis shows that graphite was successfully oxidised and exfoliated to GO. The FTIR analysis confirms the presence of C–O, C=C, and O–H bonds in the synthesised GO. The amount of GO added to the WBDF was varied and changes in the rheological properties (density, plastic viscosity, yield point and mud cake thickness) were studied. It was observed that drilling fluid developed using GO has better rheological and filtration properties than drilling fluid formulated without GO. The mud thickness was reduced after the addition of GO, indicating that GO-WBDFs have the capability to control fluid loss into the formation during drilling activities.

Investigation Into Local Additives as Substitute to Standard Viscosifier; Advances in Drilling Technology

In Nigeria, drilling companies import a bulk of drilling fluid materials that they use to carry out their respective operations. This has been a major concern to oil and gas industries since these drilling fluid materials cannot be recycled, are highly expensive in terms of foreign exchange, are not environmentally friendly, not very effective, and non-biodegradable. This work presents an experimental investigation into the reliability of the use of local materials as a substitute to conventional viscosifiers. Local materials used in the analysis are mucuna solannie (Ukpo), brachystegia eurycoma (Achi), and detarium microcarpium (Ofo). The results obtained from the experimental analysis show that they compared closely to the standard viscosifer formulated with Pac-R. The results showed that the density, specific gravity, pH, yield stress, gel strength, plastic viscosity, and yield point of mud formulated from local materials compared favorably with that of the imported viscosifier. An increase in concentration of the local sample also favoured its potential to replace the Pac-R. In terms of cost, cutting carrying ability, and positive environmental impacts, the local materials could serve the Nigerian drilling company better.

Utilization of mesoporous nano-silica as high-temperature water-based drilling fluids additive: Insights into the fluid loss reduction and shale stabilization potential

Optimally performing drilling fluids play a vital role in drilling operations. The demand for thermally stable drilling fluid in the oil and gas sector necessitates using advanced additives to create suitable formulations. This research study introduces the novel application of Mesoporous Nano-Silica (MNS) to enhance water-based drilling fluid's inhibitive, rheological, and fluid loss characteristics. MNS was synthesized by the sol-gel technique with Cetyltrimethylammonium Bromide (CTAB) for generating the pores. The hydrodynamic particle size of the synthesized MNS was 134.47 nm with a stable zeta potential of −32.2 meV. Brunauer-Emmett-Teller (BET) analyzer estimated the specific surface area to be 626 m2/g and the pore volume to be 0.3415 cm3/g. A comparative analysis of the drilling fluid properties is presented in which MNS was added to the fixed base formulation at varied concentrations (0.05, 0.1, 0.2, 0.5, and 1 wt%). Samples were subjected to hot rolling at 180 °C temperatures at 100 psi pressure for 16 h, evaluating the influence of thermal aging on the properties of the drilling fluid. The viscometric investigation was performed at 25 and 70 °C while the inhibitive properties were checked via shale recovery test and capillary suction timer. The filtration properties were examined at 100 psi and 500 psi pressure at 150 °C. The experimental findings reveal that MNS can substantially improve the thermal properties of water-based drilling fluids, maintaining rheological characteristics and drastically reducing fluid loss while imparting some inhibitive properties. Interestingly, after hot rolling the plastic viscosity of MNS-infused mud was 77% better than that of the base mud. Incorporating macro-sized particles and MNS nanoparticles into water-based drilling fluids can enhance its rheological properties, reduce filtrate loss, and improve shale inhibition characteristics which may be attributed to either the size effect or the synergistic influence of materials. Therefore, including MNS as a high-performance additive may contribute to advancing drilling operations in the petroleum industry, offering valuable insights for optimizing drilling fluid formulations.

Influence of drilling mud pulsations on well cleanout efficiency

Purpose. Determination of the influence of the non-stationary flow regime of the drilling mud on the efficiency of cleaning the wellbore in the annulus from drill cuttings. Methodology. The study on the carrying capacity of the drilling mud in a laboratory installation is carried out by simulating the process of its pulsations at different frequencies. The choice of the studied frequencies was made on the basis of previous studies. The evaluation of the influence of factors on the efficiency of rock removal was carried out using Latin experimental plans, which allowed us to evaluate the influence of the selected factors with a minimum number of experiments without losing the quality of the result. Findings. The influence of factors (mud flow rates, eccentric placement of the drill string, plastic viscosity of the drilling mud, pulsation frequency, rotation of the drill string) on the efficiency of cuttings removal along the annular space of the wellbore is analyzed. Three factors with the best interaction were found, which made it possible to build dependencies of their influence on the efficiency of rock removal on the surface. The effect of changing the frequency of pulsations of the drilling mud has been studied, and graphical dependences of their influence on the decrease in the volume of rock particles in the annular space have been obtained. Originality. Based on the results of experimental studies, the effectiveness of the impact of drilling mud pulsations on cleaning the well from rock particles has been proven. Practical value. The effectiveness of the use of drilling mud pulsations for hydrotransportation of cuttings along the horizontal section of the wellbore has been confirmed.

ENHANCING THE RHEOLOGICAL PROPERTIES OF OIL-BASED MUD THROUGH THE INCORPORATION OF POTATO STARCH

Oil-based drilling muds are effective in protecting formation integrity and resisting high temperatures, but additives are necessary to optimize their performance. This study proposes using potato starch as an additive to improve the performance of oil-based drilling mud. Potato starch was chosen because of its ability to act as a viscosifier or thickener that remains unaffected by water salinity. The research involved adding different concentrations of potato starch to a fresh oil-based drilling mud, with two Oil-to-Water Ratio (OWR) ratios, 75:25 and 80:20, employed for the two trials. Rheological testing was utilized to assess the influence of potato starch additives on the viscosity, gel strength, plastic viscosity, and yield point of drilling mud. The findings showed that the incorporation of potato starch in oil-based drilling mud can enhance its rheological values. Using potato starch as an additive offers the potential to tackle wells that have formation conditions that are brittle and sensitive to water and high temperatures. This research provides novel insights into the development of more effective and eco-friendly drilling mud formulations.

Automated Control of the Fresh State of Industrial Concrete Behaviour by Rheometer Test Adjustment

This study aimed to develop a rheometer prototype and define a procedure for adjusting the automated control of the fresh state of concrete. Sixteen batches were produced, and their fresh behaviour was measured at different testing times by applying the Abrams cone and flow curve test (FCT) as the rheological protocol. During this test, the yield stress and plastic viscosity of the concretes were measured in relative units. The rheometer prototype was used to define a new protocol to select the most suitable rheometer impeller arrangement and optimal FCT configuration. This protocol considers the torque at the end of the breakdown period, torque reduction during the breakdown period, segregation, and negative values of the yield stress in relative units. This protocol also enabled an iterative adjustment procedure, facilitating the use of a rheometer for the automated control of the homogeneity and behaviour of fresh concrete, as well as real-time decision making.

Casting Simulation of Large-Volume Fluid Cementitious Materials: Effect of Material Properties and Casting Parameters.

The increasing pressure of traffic congestion on socio-economic development has made the construction of cross-water transportation ever more crucial. The immersed tunnel method is among the most extensively employed. However, a critical challenge of the immersed tunnel technique is to ensure the compactness and stability of concrete during the casting process. Conventional laboratory methods face challenges in achieving large-volume concrete casting, resulting in the notable waste of human and material resources. Hence, this study employs a simulation approach to investigate the casting parameters and the fresh properties of concrete, exploring their impacts on concrete stability and compactness. The results indicate that when the surface tension of concrete exceeds 0.03 N/m, and the yield stress and plastic viscosity are 50 Pa and 50 Pa·s, respectively, the concrete exhibits excellent casting compactness. A design incorporating three large and six small outlets, paired with a casting speed of 3 cm/s, achieves superior compactness. Additionally, when the yield stress of concrete exceeds 3 Pa, there is no segregation of aggregates. In cases where segregation occurs, the thixotropic property of the cement paste contributes to a significant reduction in the velocity of aggregate segregation.

Exploring the piezoresistive sensing behaviour of ultra-high performance concrete: Strategies for multiphase and multiscale functional additives and influence of electrical percolation

Self-sensing ultra-high performance concrete (UHPC) features superior mechanical capacity, excellent erosion resistance, long life cycle, and broad range of stress sensing, and is expected to be a pathway towards next-generation smart cementitious composites. This study presents a novel strategy to achieve electrical percolation and elevate the piezoresistive sensing capability of UHPC through the incorporation of multiphase and multiscale functional additives including graphene (G) and carbon nanotube (CNT). The workability, compressive strength, microstructural characteristics, and alternating current (AC) impedance response are investigated. The effect of electrical percolation on the piezoresistive behaviour is studied and discussed using various ratios of G/CNT. Results indicate that as the G/CNT ratio decreases from 4:0 to 0:4, the compressive strength is reduced from 194.7 MPa to 166.3 MPa due to the certain increase in the plastic viscosity of fresh mixture and the proportion of harmful pores, although the basic requirement of 150 MPa is met. Moreover, the AC impedance response significantly moves left and the radius of high-frequency arc reduces from 72910 Ω to 1295 Ω, suggesting electrical percolation. Bounded by percolation threshold, the fractional change of resistance curves can be divided into a two-stage pattern (i.e., linear and nonlinear stages) and a three-stage mode (i.e., linear decrease, balance, and abrupt increase stages). An underlying mechanism is proposed to explain the tremendous change in piezoresistive behaviour of self-sensing UHPC, considering the tunneling-percolation theory and electromechanical coupling behaviour. Additionally, the gauge factors range from 11 to 28, which is higher than most of the existing reported values, demonstrating the great potential of using hybrid functional nano-additives in self-sensing UHPC.

CHARACTERISTICS OF CENTRIFUGAL PUMP FOR PUMPING BINGHAM LIQUID WITH DIFFERENT VALUES OF YIELD STRESSES

General techniques for designing centrifugal pumps are based on calculation features and experimental data on water pumping. On the other hand, pumping non-Newtonian liquids, and Bingham liquids in particular, can change the position of the best efficiency points and change the characteristics. The use of numerical methods allows not only to speed up the search for optimal flow parts, but also to check the possibility of pump operation under extreme operating parameters with different viscosities of a non-Newtonian liquid: from zero viscosity (ideal liquid) to extremely high values, and to create more universal design methods pumps of various types. General techniques for designing centrifugal pumps for pumping non- Newtonian fluids involve adjusting the characteristic depending on the effective viscosity, which for Bingham fluid is calculated from the plastic viscosity. The paper determines the influence of the values of the yield stresses of the Bingham fluid on the characteristics of the centrifugal pump by solving the Reynolds equations, continuity, the turbulence model and the rheological model of the Bingham fluid. It was found that with the same flow rate, the pressure at the pump outlet decreases by no more than 5,1 %. There is a slight shift in the characteristic to the zone of lower flow rate. Thus, the yield stresses have practically no effect on the pressure characteristic of the centrifugal pump. The yield stresses have a sufficient influence on the pump efficiency that they must be considered during the design of the flow part. The efficiency decreases by 10 % when pumping liquid with yield stresses of 100 Pa. A decrease in the efficiency of the pump may be related to the kinematic parameters of the pump and the result of a decrease in pressure distribution on the blade.

Study on rheological property, volumetric deformation, mechanical strength and microstructure of mortar incorporated with waste glass powder (WGP)

To achieve a much better utilization the medium and small particle size of WGP, this study investigated the effect of WGP with different particle sizes (6.63 μm, 18.33 μm, 30.15 μm and 49.38 μm) and replacement ratios (3.0 %, 6.0 %, 9.0 %, 12.0 % and 15.0 %), as the supplementary cementitious materials, on the performance of the mortar. First, the rheological properties of the fresh mortar was evaluated by using Bingham model, Modified Bingham model, and H-B model; Second, the autogenous shrinkage and dry-wet cycling deformation of the hardened mortar were monitored; Finally, the micromorphology, weight loss and crystalline structure of hydration products were analyzed by SEM, TG and XRD. The results show that, for the fresh mortar with WGP, Modified Bingham model is more suitable for estimating the yield stress (τ0) and H-B model is more appropriated to interpret the plastic viscosity. As the averaged diameter of WGP increased, the yield stress (τ0) emerged a reversed S-shaped variation tendency; the flow index (n) remains relatively minor scatter and change slightly, ranging from 0.6 to 0.88; the plastic viscosity varied with a little fluctuation with the scope of 4.0 Pa·s to 5.94 Pa·s. The contents of the WGP had great influences on the autogenous shrinkage of the mortar, the tremendously change mainly taken placed in the rapidly increase stage; with the condition of same WGP content, the particle size of the WGP has a minimal impact on the autogenous shrinkage; under the drying and wetting cycle environment from 28 days to 140 days, the deformation rate changed in a way of sinusoidal wave. The addition of WGP can further reduce the heat of hydration of the hardened cement paste, and the rate of hydration heat peaked at about 20 h, there is no reaction occurred for 49.38 μm WGP with calcium hydroxide (CH).

Printability and shape fidelity evaluation of self-reinforced engineered cementitious composites

Incorporating fibers into Engineered Cementitious Composites (ECC) renders it a promising self-reinforced candidate for additive manufacturing, which can effectively address the challenges of reinforcement and automation. Considering this research challenge the current study aimed at designing 3D printable ECC mixes. The problems involved in the printability of ECC such as poor extrudability, buildability and shape retention, were addressed by utilizing the methylcellulose (MC) as a viscosity-modifying admixture. The results indicated that adding 1 % MC improved the fiber dispersion coefficient by 28 % and increased static yield stress in a range of 4 % to 237 % and plastic viscosity in the range of 247 % to 950 % in four different ECC mixes. Accordingly, the dimensional conformity of 3D printed filaments was considerably improved, and all designed ECC mixes meet the extrudability and buildability requirements.

Evaluation of Using Fly Ash as a Weighing Material for Oil-Based Drilling Fluid.

Innovation and sustainability are essential in the fast-changing oil and gas business. Fly ash, a byproduct of coal combustion in power plants and factories, has become a valuable resource in many industries, changing the concept of waste materials. Fly ash is essential to sustainable development and environmental care due to its unique qualities and multiple applications. In the drilling industry, a well-designed drilling fluid is essential and this requires the use of various additives that serve specific functions to achieve a successful borehole. This study investigates the use of fly ash as a weighing material in oil-based mud, with the intent to develop an economically acceptable drilling fluid system using industrial waste. The study compared fly ash to three commonly used weighing materials in the drilling industry: calcium carbonate (CaCO3), barite (BaSO4), and ilmenite (FeTiO3). Drilling fluids were prepared using these weighing materials at various weights, and their properties (density, electrical stability, rheological features, and filtration properties) were measured using API-recommended methods. The rheology and filtration tests were conducted at elevated temperatures (350 °F). The results indicate that fly ash has the potential to be a useful weighing material in drilling operations. It can increase the fluid density up to 10 ppg without affecting the rheological properties at 350 °F. Additionally, the electrical stability of the drilling fluid was enhanced compared to the other used weighing materials. The addition of fly ash also improved rheological characteristics such as plastic viscosity, yield point, and gel strength without affecting HPHT filtration properties. The carrying capacity was improved by 53 and 86% over calcium carbonate and barite, respectively. Overall, the findings suggest that fly ash can be a viable alternative to other weighing materials in the recommended density range.

Effect of cement kiln dust and lignosulfonate on cement paste: a rheology and hydration kinetics study

This research provides a comprehensive analysis of the influence of cement kiln dust (CKD) and lignosulfonate (LS) on the rheology and hydration kinetics of cement paste. The interaction effect, dispersion potential, and adsorption kinetics of LS on the cement/CKD paste were obtained using UV spectroscopy and zeta potential measurements. The results indicate that the addition of LS reduces the yield stress and plastic viscosity through the dispersion effect of LS, which alters the adhesion of the particles and improves the rheology of the CKD/cement paste. The competing adsorption of LS by the cement and CKD particles increased the flowability of the cement paste and a maximum was obtained due to the stable combined action of two different mechanisms of steric hindrance and electrostatic repulsion by LS. The X-ray Diffraction analysis performed to evaluate the hydration response of cement with LS and CKD showed greater conversion potentials of SiO2 to stable CSH.

Printability and early mechanical properties of material composition modified 3D printing engineered cementitious composites based on the response surface methodology

To explore the influence mechanism between material composition and the early performance of 3D printing engineered cementitious composites (3DP-ECC). In this paper, the effects of different dosages of fly ash (FA), Sand and hydroxypropyl methylcellulose (HPMC) on the printability and early mechanical properties of 3DP-ECC were studied based on response surface method (RSM). The results revealed that with the increase of HPMC dosage, the yield stress and plastic viscosity gradually increased, and the mechanical properties initially increased and then decreased. With the increase of FA dosage, the yield stress initially decreased and then increased, and the plastic viscosity gradually decreased. At the same time, the compressive strength reduced and the tensile properties were improved. The optimal dosages of 28–29% FA, 0.545–0.550 sand to binder rate (S/B) and 0.302–0.305% HPMC were determined by RSM. It provided a theoretical basis for the calculation and analysis of ECC components and structures in 3D printing.

Synergistic effect of PTB emulsion, CaCO3 whisker and Nano-SiO2 on the properties of cement-based materials

With the rapid development of the civil engineering industry, performance requirements for building materials are also increasing rapidly. It is particularly critical to improve the performance of cement-based materials using admixtures. In this study, the synergistic effect of PTB (COMPAKTUNA.PRO) emulsion, calcium carbonate whisker (CaCO3 whisker) and nano-silica (nano-SiO2) on material properties was analyzed. Macroscopic properties such as rheology, compressive strength, flexural strength, durability, bond strength, and permeable pressure were tested. Microstructures were analyzed using the porosity, hydration heat, X-ray diffraction, and scanning electron microscopy methods. The results revealed that the PTB emulsion, CaCO3 whiskers, and nano-SiO2 increased the plastic viscosity and yield stress of the cement. When the nano-SiO2 content was high, the fluidity of the slurry decreased significantly. Overall, PTB emulsion, CaCO3 whisker and nano-SiO2 can improve the strength, durability, bond strength, and permeability of composite materials. PTB emulsions can prolong the hydration process, resulting in low early strength and reduced compressive strength. However, they play a key role in terms of improving durability, bond strength, and permeability pressure. CaCO3 whiskers yield slight improvements in various properties. Nano-SiO2 can promote the hydration rate and hydration effect, thereby improving the strength, compactness, and properties of composite materials. Performance can be optimized by leveraging these synergistic effects and each material has its own unique advantages and limitations. In engineering applications, critical properties should be considered when selecting appropriate admixture contents. This study aimed to improve various properties and to develop materials that are suitable for the complex environment of underground engineering.

Applicability of sawdust as a green additive to improve the rheological and filtration properties of water-based drilling fluid: an experimental investigation

Drilling fluid is essential to oil and gas drilling operations due to its diverse functionality. But the most commonly used drilling fluid additives are hazardous chemicals and are not biodegradable. As a result, the demand for environment-friendly additives has been raised to replace the hazardous chemical additives. Considering the rising interest toward green additive, this study examined the applicability of sawdust to be used as a biodegradable drilling fluid additive to improve the rheological and filtration properties of water-based mud. Sawdust was chosen for this study because of its high cellulose content, widespread availability, and low cost. Following the guidelines set by the American Petroleum Institute (API), we carried out laboratory experiments that encompassed three distinct concentrations of sawdust: sample 1 (with 0.25% sawdust), sample 2 (with 0.50% sawdust), and sample 3 (with 0.75% sawdust). The concentrations of sawdust were measured as a weight percentage of the total volume of the base water. Concentrations above 0.75% led to gelation issues. Results showed minimal impact on mud weight at 0.25% sawdust, while 0.50 and 0.75% concentrations caused slight weight reduction due to foam development. Plastic viscosity increased by 28.5, 42.8, and 71.4% for sample 1, sample 2, and sample 3, respectively, compared to the base mud. Sawdust-containing mud exhibited desirable gel strength and shear-thinning behavior. Moreover, sawdust significantly improved filtration properties by reducing fluid loss and mud cake thickness. Sample 2 (0.5% sawdust) performed well in terms of filtration properties. Mud cake permeability followed the trend: kBM>k0.75%sawdust>k0.25%sawdust>k0.50%sawdust\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${k}_{\\mathrm{BM}}>{k}_{0.75\\% \\mathrm{sawdust}}>{k}_{0.25\\% \\mathrm{sawdust}}>{k}_{0.50\\% \\mathrm{sawdust}}$$\\end{document}. Based on promising laboratory performance, lower concentrations of sawdust are recommended as a cost-effective and eco-friendly additive to enhance rheological and filtration properties of water-based drilling fluid systems.

Rheological behavior of dehydrated cranberry suspensions: Analysis of the influence of temperature and solid concentration on Casson’s model parameters

Dehydrated cranberries (Vaccinium macrocarpon) are dried fruits known for their high antioxidant potential. Changes in their mechanical and rheological properties occur when cranberries are exposed to certain conditions, such as drying or immersion in a liquid medium (rehydration). To evaluate the rheological behavior of solid suspensions made from dehydrated cranberries, the effects of different temperatures and concentrations of dissolved solids were evaluated using a factorial experimental design (22) with three replications at the center point. Five models were used to investigate the suspensions' flow behavior: Ostwald de Waelle, Newton, Herschel-Bulkley, Casson, and Bingham. The rheometry of the suspensions showed that the fluids presented non-Newtonian behavior, with a satisfactory fit for the Casson model (R² > 0.94) in all evaluated temperature and concentration ranges. Furthermore, the effects of temperature and solid concentration of cranberry suspensions on the rheological parameters of the fitted model, Casson's initial shear stress (K0c), and Casson's plastic viscosity (Kc) were evaluated. From the response and the contour surfaces, it was found that increasing the concentration of the suspension above 20% resulted in higher initial shear stress, which was influenced by temperature, whose increase resulted in a significant reduction in the shear stress at a concentration of 30%. The plastic viscosity (Kc) was highly influenced by the solid’s concentration, and higher temperatures caused a decrease in the value of this parameter. So, the highest value of plastic viscosity was found for concentrations above 20% and at lower temperatures. Therefore, considering the results and for practical purposes, it can be concluded that the flow of the suspensions is facilitated if rehydration is conducted at high temperatures.

Optimization on the mix design method of self-compacting concrete with recycled coarse aggregate based on paste rheological threshold theory and material packing characteristics

This study aims to use the mixture design method to optimize self-compacting concrete (SCC) and manufacture SCC with excellent workability using recycled coarse aggregate (RCA) and a ternary cementitious system. The influences of incorporated RCA on the rheological thresholds of SCC with a fixed content of fly ash (FA) and blast furnace slag (BFS) are investigated based on paste rheological threshold theory and material packing characteristics. The original rheological model is improved by introducing the volume of adhesive mortar and modifying the equivalent packing density and mortar film thickness. The improved model is incorporated into the original theoretical system to apply the optimized mix design method to SCC. Moreover, experiments are conducted with different volumes of water, water-powder ratios and RCA replacement levels to verify the applicability of the optimized method. The results indicate that the proposed models can accurately predict the yield strength threshold and plastic viscosity threshold of fresh SCC. Furthermore, compared to the original model, predictions are 53% more accurate with the modified model.