Natural rubber latex as a potential additive for water-based drilling fluids

The environmental hazards and"carbon footprint"of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals.This paper explored for the first time the interaction mechanism between natural rubber latex(NRL)and bentonite suspensions(BTs)through a series of characterization experiments,as well as the potential applications in water-based drilling fluids(WBDF).The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k)and flow index(n)of BTs,and enhance the shear thinning performance of BTs as pseudo-plastic fluids.In addition,0.5 w/v%NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles,but also facilitated the compatibility of pressure loss and flow efficiency.The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles,and optimize the particle size distribution and flow resistance of WBDF under the"intercalation-exfoliation-encapsulation"synergistic interaction.Moreover,NRL can improve the rheological properties of WBDF at high temperatures(<150.C),and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake,which ultimately reduces the permeability of the cake and the filtration loss of WBDF.

An Investigation into Forced Convection of a Nanofluid Flowing in a Rectangular Microchannel under the Influence of a Magnetic Field

In line with recent studies,where it has been shown that nanofluids containing graphene have a stronger capacity to boost the heat transfer coefficient with respect to ordinary nanofluids,experiments have been conducted using water with cobalt ferrite/graphene nanoparticles.In particular,a circular channel made of copper subjected to a constant heatflux has been considered.As nanoparticles are sensitive to the presence of a magneticfield,different conditions have been examined,allowing both the strength and the frequency of such afield to span relatively wide ranges and assuming different concentrations of nanoparticles.According to thefindings,the addition of nanoparticles to thefluid causes its rotation speed to increase by a factor of two,whereas ultraviolet radiation plays a negligible role.The amount of time required to attain the maximum rotation speed of the nanofluid and the Nusselt number have been measured under both constant and alternating magneticfields for a ferrofluid with a concentration of 0.5%and atflow Reynolds number of 550 and 1750.

Research on heat dissipation characteristics of magnetic fluid bearings under multiple field coupling effects

This paper analyzes the sources of heat losses in magnetic fluid bearings,proposes various cou-pling relationships of physical fields,divides the coupled heat transfer surfaces while ensuring the continuity of heat flux density,and analyzes the overall heat dissipation pathways of the bearings.By changing parameters such as input current,rotor speed,and inlet oil flow rate,the study applies a multi-physics field coupling method to investigate the influence of different parameters on the temper-ature field and heat dissipation patterns of the bearings,which is then validated through experi-ments.This research provides a theoretical basis for the optimal design of magnetic fluid bearing sys-tems.

Friction Behavior of Magnetorheological Fluids with Different Material Types and Magnetic Field Strength

Magnetorheological （MR） fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic field, which is known as MR effect, resulting in variation of stiffness, shear modulus, damping and tribological characteristics of MR fluid. As MR effect depends on the density of particles in the fluid or the strength of a magnetic field, the experiments are conducted to evaluate the friction property under reciprocating motion by changing the types of MR fluid and the strength of a magnetic field. The material of aluminum, brass, and steel are chosen for specimen as they are the most common material in mechanical applications. The surfaces of specimen are also observed by optical microscope before and after experiments to compare the surfaces with test conditions. The comparing results show that the friction coefficient increases as the strength of a magnetic field increases in regardless of types of MR fluid or the material. Also the density of particle in MR fluid affects the friction characteristic. The results from this research can be used to improve the performance of mechanical applications using MR fluid.

Sealing mechanism of magnetic fluids

Sealing is one of the most successful apphcatious of magnetic fluids. However, the sealing pressure difference is not satisfactory. This paper theoretically analyzes the mechanism of magnetic fluids sealing. Main factors that have significant effects on the sealing ability include viscous stress on the interracial surface, magnetic surface tension, and the shape of the interracial surface. The sealing pressure with magnetic fluids decreases with increase of rotational speed. Experiments were carried out to study the stability of the interface between magnetic fluids and water. It has been shown that stability of the interface will be damaged by washing of water when the relative flow between water and magnetic fluid becomes turbulent.

High temperature and high pressure rheological properties of high-density water-based drilling fluids for deep wells

To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.

Application of sustainable basil seed as an eco-friendly multifunctional additive for water-based drilling fluids

Basil seed,containing anionic heteropolysaccharides in its outer pericarp,swells as gelatinous hydrocolloid when soaked in water.In this study,basil seed powder(BSP)was used as a multifunctional additive for water-based drilling fluids.The chemical composition,water absorbency,rheological properties of aqueous suspension of BSP were tested.The effect of BSP on the rheological and filtration of bentonitebased drilling fluid before and after thermal aging was investigated.The inhibition characteristics were evaluated by linear swelling,shale cuttings dispersion and shale immersion test.Lubricity improvement by BSP was measured with extreme pressure lubricity test.The results revealed that incorporation of BSP into bentonite suspension improved rheological and filtration properties effectively after thermal aging of 120℃.BSP exhibited superior inhibitive capacity to xanthan and synergistic effect with KCl.BSP could reduce friction by forming hydration layer.The nanoscale three-dimensional network structures enable BSP to maintain high water retention and absorb strongly on bentonite and metal surface,contributing to enhanced rheology,filtration,inhibition and lubrication properties.The versatile characteristic of BSP,as well as biodegradation makes it a promising additive using in high performance water-based drilling fluid and a potential alternative to conventional synthetic polymers.

Improving the anti-collapse performance of water-based drilling fluids of Xinjiang Oilfield using hydrophobically modified silica nanoparticles with cationic surfactants

Wellbore instability,especially drilling with water-based drilling fluids(WBDFs)in complex shale for-mations,is a critical challenge for oil and gas development.The purpose of this paper is to study the feasibility of using hydrophobically modified silica nanoparticle(HMN)to enhance the comprehensive performance of WBDFs in the Xinjiang Oilfield,especially the anti-collapse performance.The effect of HMN on the overall performance of WBDFs in the Xinjiang Oilfield,including inhibition,plugging,lu-bricity,rheology,and filtration loss,was studied with a series of experiments.The mechanism of HMN action was studied by analyzing the changes of shale surface structure and chemical groups,wettability,and capillary force.The experimental results showed that HMN could improve the performance of WBDFs in the Xinjiang Oilfeld to inhibit the hydration swelling and dispersion of shale.The plugging and lubrication performance of the WBDFs in the Xinjiang Oilfield were also enhanced with HMN based on the experimental results.HMN had less impact on the rheological and filtration performance of the WBDFs in the Xinjiang Oilfield.In addition,HMN significantly prevented the decrease of shale strength.The potential mechanism of HMN was as follows.The chemical composition and structure of the shale surface were altered due to the adsorption of HMN driven by electrostatic attraction.Changes of the shale surface resulted in significant wettability transition.The capillary force of the shale was converted from a driving force of water into the interior to a resistance.In summary,hydrophobic nanoparticles presented afavorable application potential for WBDFs.

A new environmentally friendly water-based drilling fluids with laponite nanoparticles and polysaccharide/polypeptide derivatives

Considering the increasing environmental pressure,environmentally friendly and high-performance water-based drilling fluids(WBDFs)have been widely studied in recent years to replace the commonly used oil-based drilling fluids(OBDFs).However,few of these drilling fluids are entirely composed of natural materials,which makes it difficult to achieve real environmental protection.Using laponite nanoparticles and various derivatives of natu ral mate rials,including cro sslinked starch,cellulose composite,gelatin ammonium salt,poly-l-arginine,and polyanionic cellulose,a kind of environmentally friendly water-based drilling fluid(EF-WBDF)was built for drilling in environment-sensitive areas.The properties of this EF-WBDF were evaluated by thermal stability tests on rheology,filtration,inhibition,and salt contamination.Besides,biological toxicity,biodegradability,heavy mental content and wheat cultivation tests were conducted to investigate the environmental factor of EF-WBDF.Results showed that EF-WBDF displayed satisfactory thermal resistance up to 150℃,and the rheological properties did not suffer significant fluctuation,showing potential application in high-temperature wells.The optimal rheological model of EF-WBDF was Herschel-Bulkley model.This EF-WBDF performed an eligible filtration of 14.2 mL at 150℃and a differential pressure of 3.5 MPa.This fluid could still maintain colloidal stability after being contaminated by 7.5%NaCl or 0.5%CaC1_(2).Meanwhile,rather low clay swelling degree of 2.44 mm and high shale recovery of more than 95%ensured the inhibitive capability of EF-WBDF.Furthermore,EF-WBDF presented a half maximal effective concentration(EC_(50))of51200 mg/L and a BOD/COD ratio of 47.55%,suggesting that EF-WBDF was non-toxic and easily biodegradable.The wheat cultivated in EF-WBDF could grow healthily,beneficial for reducing the adverse impact on ecological environment.The formed EF-WBDF has a promising future for drilling in environment-sensitive and high-temperature areas.

Investigation of regulating rheological properties of water-based drilling fluids by ultrasound

Regulating rheological properties of water-based drilling fluids has always been a hot topic.This paper proposed a new method for regulating rheological properties of water-based drilling fluids by ultrasonic field.The experimental results showed that the ultrasound increased the viscosity and yield point of bentonite suspension by reducing the particle size of clay,destroying the network structure between clay particles,increasing the mud yield and the cation exchange capacity of bentonite,and promoting the hydration dispersion of bentonite.The change of rheological property showed a memory effect at room temperature and high temperature.Besides,the ultrasonic energy affected the network structure between clays and polymer chains,thus regulating the rheological properties of the bentonite-polymer system.For two types of drilling fluids investigated,the rheology of the poly-sulfonate drilling fluid was regulated by damaging the grid structure between additives and clays by low-power ultrasound and reducing the clay particle size by high-power ultrasound,while the rheology of the deep-water drilling fluid was mainly regulated by disentangling the spatial grid structure between additives.Additionally,ultrasound showed no effect on the lubricity,inhibition and stability of drilling fluids,which proved the feasibility of ultrasound to regulate rheological properties of water-based drilling fluids.

Stability of plane-parallel flow of magnetic fluids under external magnetic fields

In this work,we present a theoretical study on the stability of a two-dimensional plane Poiseuille flow of magnetic fluids in the presence of externally applied magnetic fields.The fluids are assumed to be incompressible,and their magnetization is coupled to the flow through a simple phenomenological equation.Dimensionless parameters are defined,and the equations are perturbed around the base state.The eigenvalues of the linearized system are computed using a finite difference scheme and studied with respect to the dimensionless parameters of the problem.We examine the cases of both the horizontal and vertical magnetic fields.The obtained results indicate that the flow is destabilized in the horizontally applied magnetic field,but stabilized in the vertically applied field.We characterize the stability of the flow by computing the stability diagrams in terms of the dimensionless parameters and determine the variation in the critical Reynolds number in terms of the magnetic parameters.Furthermore,we show that the superparamagnetic limit,in which the magnetization of the fluids decouples from hydrodynamics,recovers the same purely hydrodynamic critical Reynolds number,regardless of the applied field direction and of the values of the other dimensionless magnetic parameters.

Super-amphiphobic, strong self-cleaning and high-efficiency water-based drilling fluids

Based on the amphiphobic theory on underground rock surface, a super-amphiphobic agent is developed and evaluated which can form nano-micro papilla structure on rock, filter cake and metal surface, reduce surface free energy, prevent collapse, protect reservoir, lubricate and increase drilling speed. With this super-amphiphobic agent as the core agent, a super-amphiphobic, strong self-cleaning and high-performance water-based drilling fluid system has been developed by combining with other agents based on drilled formation, and compared with high-performance water-based drilling fluid and typical oil based drilling fluid commonly used in oilfields. The results show that the super-amphiphobic, strong self-cleaning and high-performance water-based drilling fluid has better rheology, and high temperature and high pressure filtration similar with that of oil-based drilling fluid, inhibiting and lubricating properties close to oil based drilling fluid. Besides, the super-amphiphobic system is non-toxic, safe and environmentally friendly. Field tests show this newly developed drilling fluid system can prevent wellbore collapse, reservoir damage and pipe-sticking, increase drilling speed and lower drilling cost, meeting the requirement of safe, high efficient, economic and environmentally friendly drilling. Compared with other drilling fluids, this new drilling fluid system can reduce downhole complexities by 82.9%, enhance the drilling speed by about 18.5%, lower drilling fluid cost by 39.3%, and increase the daily oil output by more than 1.5 times in the same block.

Process Modeling of Ferrofluids Flow for Magnetic Targeting Drug Delivery

Among the proposed techniques for delivering drugs to specific sites within the human body, magnetic targeting drug delivery surpasses due to its non-invasive character and its high targeting efficiency. Although there have been some analyses theoretically for magnetic drug targeting, very few researchers have addressed the hydrodynamic models of magnetic fluids in the blood vessel of human body. This paper presents a mathematical model to describe the hydrodynamics of ferrofluids as drug carriers flowing in a blood vessel under the applied magnetic field. A 3D flow field of magnetic particles in a blood vessel model is numerically simulated in order to further understand clinical application of magnetic targeting drug delivery. Simulation results show that magnetic nanoparticles can be enriched in a target region depending on the applied magnetic field intensity. Magnetic resonance imaging confirms the enrichment of ferrofluids in a desired body tissue of Sprague-Dawley rats. The simulation results coincide with those animal experiments. Results of the analysis provide the important information and can suggest strategies for improving delivery in favor of the clinical application.

Tunable negative-index photonic crystals using colloidal magnetic fluids

The model of using colloidal magnetic fluid to build tunable negative-index photonic crystal is established. The effective permittivity εe and permeability μe of the two-dimensional photonic crystal are investigated in detail. For transverse magnetic polarization, both εe and μe exhibit a Lorentz-type anomalous dispersion, leading to a region where εe and μe are simultaneously negative. Then, considering a practical case, in which the thickness of photonic crystal is finite, the band structures for odd modes are calculated by the plane wave expansion method and the finite-difference time-domain method. The results suggest that reducing the external magnetic field strength or slab thickness will weaken the periodic modulation strength of the photonic crystal. Simulation results prove that the negative-index can be tuned by varying the external magnetic field strength or the slab thickness. The work presented in this paper gives a guideline for realizing the flat photonic crystal lens with tunable properties at optical frequencies, which may have potential applications in tunable near-field imaging systems.

Hydrophobic Small-Molecule Polymers as High-Temperature-Resistant Inhibitors in Water-Based Drilling Fluids

Water-based drilling fluids can cause hydration of the wellbore rocks,thereby leading to instability.This study aimed to synthesize a hydrophobic small-molecule polymer(HLMP)as an inhibitor to suppress mud shale hydration.An infrared spectral method and a thermogravimetric technique were used to characterize the chemical composition of the HLMP and evaluate its heat stability.Experiments were conducted to measure the linear swelling,rolling recovery rate,and bentonite inhibition rate and evaluate accordingly the inhibition performance of the HLMP.Moreover,the HLMP was characterized through measurements of the zeta potential,particle size distribution,contact angles,and interlayer space testing.As confirmed by the results,the HLMP could successfully be synthesized with a favorable heat stability.Furthermore,favorable results were found for the inhibitory processes of the HLMP on swelling and dispersed hydration during mud shale hydration.The positively charged HLMP could be electrically neutralized with clay particles,thereby inhibiting diffusion in the double electron clay layers.The hydrophobic group in the HLMP molecular structure resulted in the formation of a hydrophobic membrane on the rock surface,enhancing the hydrophobicity of the rock.In addition,the small molecules of the HLMP could plug the spaces between the layers of bentonite crystals,thereby reducing the entry of water molecules and inhibiting shale hydration.

Magnetic Field Effect and Heat Transfer of Nanofluids within Waveform Microchannel

In this research,a numerical study of mixed convection of non-Newtonian fluid and magnetic field effect along a vertical wavy surface was investigated.A simple coordinate transformation to transform wavy surface to a flat surface is employed.A cubic spline collocation numerical method is employed to analyze transformed equations.The effect of various parameters such as Reynolds number,volume fraction 0-,Hartmann number,and amplitude of wave length was evaluated in improving the performance of a wavy microchannel.According to the presented results,the sinusoidal shape of the microchannel has a direct impact on heat transfer.By increasing the microchannel wave amplitude,the Nusselt number has risen.On the other hand,increasing the heat transfer in the higher wavelength ratio corrugated channel is seen as an effective method of increasing the heat transfer,especially at higher Reynolds numbers.The results showed that with increasing Hartmann numbers,the flow line near thewall becomesmore regular and,according to the temperature gradient created,theNusselt number growth.

Dysprosium Modification of Cobalt Ferrite Ionic Magnetic Fluids

Dysprosium composite cobalt ferrite ionic magnetic fluids were prepared by precipitation in the presence of Tri-sodium citrate. Influence of dysprosium modification on magnetic property is studied. The result shows that magnetic response toward exterior magnetic field can be improved by adding Dy3+. Studies also show that the increase of reaction temperature may improve the modification effect of dysprosium. By adding dysprosium ions, the average diameter of the magnetic nanoparticles will be decreased evidently. It is clear that the particles appear as balls. Cobalt ferrite with sizes of 12-15 nm, rare earth composite cobalt ferrite with sizes of 6-8 nm.

Synthesis and application of bilayer-surfactant-enveloped Fe_3O_4 nanoparticles: water-based bilayer-surfactant-enveloped ferrofluids

Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization（85 emu·g-（-1）） and high crystallinity were synthesized using polyethylene glycol-4000（PEG（4000）） as a carbon source.Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG（4000） as dispersants.Analyses using X-ray photoelectron spectroscopy,X-ray diffraction,and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG（4000）.Transmission electron microscopy,vibrating sample magnetometry,and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4（79.6 emu·g^-1） and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm,which is substantially smaller than that of the unmodified Fe3O4 nanoparticles（486.2 nm）.UV-vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L^-1,which indicates that the ferrofluids are highly stable.

Properties of magneto-rheological fluids based on amorphous micro-particles

To improve the magneto-rheological (MR) properties of magneto-rheological fluids, self-made amorphous alloy particles, the composition of which was Fe76Cr2Mo2Sn2P10B2C2Si4, were used as the disperse phase to replace traditional carbonyl iron (CI) particles to prepare amorphous based magneto-rheological fluid (AMRF). Soft magnetic properties and densities of the amorphous particles and the CI particles were tested and compared. The results indicate the amorphous particles present a lower density but larger magnetization intensity and larger permeability at lower field levels. Properties of the AMRF with 20% particles in volume fraction were tested and compared with the CI based MR fluid (CMRF). The AMRF presents a saturation yield stress of 41 kPa at ~227 kA/m and a sedimentation ratio of 80%. The results indicate the magneto-rheological fluid based on amorphous micro-particles has better MR properties and sedimentation stability than that based on CI particles at lower field levels (0-200 kA/m).

Characteristics of Nanofluids over a Non-Linearly Stretched Sheet under the Influence of Thermal Radiation and Magnetic Field

Recent studies carried out in terms of viscous flow and heat transfer of nano-fluids on the non-linear sheets. In this paper, detailed studies to understand the characteristics such as viscous flow and heat transfer of nano-fluids under the influence of thermal radiation and magnetic fields are studied using Keller-Box method. Various governing parameters affecting the viscous flow and heat transfers are drawn based on quantitative results. The raise in temperature affected the velocity to a negative value;however, the same observation was made even for the increasing magnetic field. The impact of radiation parameter is proportional seems to be proportional to temperature and it is observed to be inversely proportional with concentration.