Control Of Circulation Research Articles

Plugging performance and mechanism of an oil-absorbing gel for lost circulation control while drilling in fractured formations

Lost circulation of drilling fluid is one of the most common engineering problems in the drilling process of fractured formations. In this study, an oil-absorbing polymer gel synthesized using compound monomers with rigid and flexible chains was applied to control the oil-based drilling fluid loss while drilling. The microstructure, oil-absorbing performance, and plugging performance the gel was investigated. A large number of dense pores on the surface of the gel were observed, which allowed the oil molecules to enter the internal space of the gel. The initial oil absorption capacity of the gel was fast, and it increased with the increase in the temperature and decrease in the particle size, reaching 20.93 g/g at 140 °C. At a high temperature of 140 °C, the bearing pressure capacity of the gel formula containing particles of different particle sizes reached 7.6 MPa for a fracture of a width of 3 mm, showing that the oil-absorbing gel have excellent plugging performance at high temperature. Plugging mechanism of the gel was investigated through visualized fracture plugging experiments. Results show that the dynamic migration, particle-swelling, particle-bridging, particle-aggregation, deformation-filling, and compaction-plugging contribute to the whole lost circulation control process, reflecting that the plugging performance can be effectively enhanced by improving the aggregation and filling degrees of the gel with different particle sizes.

Vortex evolution near the Coanda surface of a circulation control airfoil with pulsed actuation

A special vortex evolution process was found near the Coanda surface for circulation control airfoil with pulsed actuation. For the jet-on process, two successive shedding vortices from the lower lip edge and the separation vortex on the Coanda surface collide and interact with each other, and periodic vortex shedding forms after several vortex shedding and collision cycles. For the jet-off process, the periodic shedding vortices were replaced by a row of vortices with reverse rotation direction from the upper lip edge, and then reverse vortices broke into small-scale vortices.

Characterization of <i>Amuda-Isuochi</i> Nigerian Clay Deposit for Potential Industrial Applications

The aim of the work was to characterize the clay from Amuda-Isuochi, Abia state Nigeria. Preliminary research works on the area is scanty. The characterization involved chemical and elemental analyses, X-ray diffraction, specific surface area analysis, thermal analyses (TGA, DTA) and particle size distribution. The results showed that the clay is kaolin. Specific surface area of 251m2/g was observed, with average particle size of 84.67d.nm and polydispersity index of 0.203. The sample will find applications in oil and gas industry as lost circulation control material and for manufacture of proppants for hydraulic fracturing activities. Similarly, it can be used as an adsorbent and has potential applications for ceramic tile, paper, paints, fibre glass and starting material for alum. The kaolin clay will also be suitable as a nano-material. The output indicates an addition to local contents for Nigeria’s industrial development.

Solar energy harvesting mechanisms of the frustules of Nitzschia filiformis diatoms

Diatoms are major contributors to the global oxygen and carbon cycles. Their ability to thrive on photosynthesis, even in low and intermittent lighting conditions, is attributed to the optical response of the frustule, among other factors. However, how the frustule functions as a biophotonic feature is unknown. Using a toolkit consisting of numerical models and four microscopy techniques, we evaluated the optical response of frustules belonging to the species Nitzschia filiformis. Localized regions of the frustule exhibited functionalities including diffraction, lensing, waveguiding, circulation, filtering, resonances, and dispersion control. We show that these functionalities are complementary to each other in contributing to the solar energy harvesting mechanisms of capture, redistribution, and retention. In this context, frustule performance is evidently enhanced by perturbations to its sub-wavelength structure. We therefore modeled the frustule as a photonic circuit from which we estimated a contribution of approximately 9.83% to photosynthetic activity. To our knowledge, this represents the first model of the entire frustule, including its inherent disorder and the complementary behavior of localized optical functionalities. This provides quantitative support to the hypothesis that the frustule enhances photosynthesis in the cell. It supports the case for cultivating diatoms as sustainably mass-manufacturable devices with applications in solar energy, carbon sequestration, sensing, medicine, and metamaterials.

Abstract 13023: Exercise Training Potentiates Diuretic Benefits on Mechanism of Arterial Pressure Control in Hypertensive Postmenopausal Rats: Role of Inflammatory and Redox Balance

Introduction: Thiazide diuretic is a classic drug used to treat elevated arterial pressure (AP). However, their neuroinflammatory effects are limited when compared with other therapies. Objective: To compare the effect of hydrochlorothiazide (HCTZ) alone or combined with concurrent exercise training (aerobic+resistance, CET) on mechanisms of AP control and on inflammatory and redox balance in hypertensive postmenopausal rats. Methods: Female spontaneously hypertensive rats were distributed into sedentary (S) and ovariectomized groups: sedentary (OS), sedentary treated with HCTZ (OSH), trained (OT) and trained treated with HCTZ (OTH). HCTZ treatment (30 mg/kg) and CET (40-60% maximal capacity, 3 days/wk) were conducted for 8wks. AP was directly recorded at rest and after vasopressor system blockade (vasopressin antagonist, losartan and hexamethonium). Inflammation and oxidative stress were evaluated in cardiac tissue. Results: Trained groups presented higher exercise tests performance. Systolic (OT:178±18 and OTH:178±17 vs. OS:205±15) and mean AP (mmHg) (OTH:153±17 vs. OS:176±16) were reduced in trained groups. CET promoted an increase in both bradycardic and tachycardic responses of baroreflex sensitivity and a reduction in AP variability indexes in relation to OS group. After sympathetic blockade, AP (mmHg) reduction was higher in OS group (-75.7±19.2 vs. S:-53.2±12.6 and OTH:-49.8±12.4). In addition, IL-10 (OTH vs. OS and OSH) and IL-10/TNF-alpha ratio (OTH vs. S, OS, OSH and OT) were higher in OTH group. OS group showed increased NAPDHoxidase and reduced catalase (vs. S); however, these changes were not observed in OTH group. Negative correlation was observed between sympathetic vascular modulation and IL/TNF-alpha ratio (p<0.001, r:-0.6). Conclusions: We concluded that CET alone or combined with HCTZ are more efficient approaches than HCTZ to reduce AP and improve AP control of circulation. Specifically, the combination HCTZ plus CET induces additional positive adaptations on physical, autonomic, inflammatory and redox balance. These results highlight the key role of exercise in the management of HTN, probably impacting on the quality of life and reducing the residual risk in post menopause. Grants: FAPESP (2019/06277-0).

Numerical simulation investigation on the suction stroke and blowing stroke of synthetic jet circulation control

Numerical simulation investigation on the suction stroke and blowing stroke of synthetic jet circulation control

Writing for Print: Publishing and the Making of Textual Authority in Late Imperial China

Writing for Print: Publishing and the Making of Textual Authority in Late Imperial China

Enhanced Respiratory Frequency Response to Lower Limb Mechanoreceptors Activation in Patients with Chronic Obstructive Pulmonary Disease.

To investigate the mechanoreflex control of respiration and circulation in patients with chronic obstructive pulmonary disease (COPD). Twenty-eight patients with moderate-to-severe COPD (mean ± SD: 67.0 ± 7.9 yr, 10 women) and 14 age- and sex-matched controls (67.9 ± 2.6 yr, 7 women) participated in the study. Their dominant knee was passively moved to stimulate mechanoreceptors, whereas vastus lateralis surface electrical activity checked active contractions. A differential pressure flowmeter, an electrocardiogram, and a servo-controlled finger photoplethysmograph acquired cardiorespiratory data. To gain insight into the mechanoreflex arc, we further analyzed reduced/oxidized glutathione ratio and mechanoreceptor-related gene expression in a vastus lateralis biopsy of additional nine patients (63.9 ± 8.1 yr, 33% women) and eight controls (62.9 ± 9.1 yr, 38% women). Patients with COPD had a greater peak respiratory frequency response (COPD: Δ = 3.2 ± 2.3 vs Controls: 1.8 ± 1.2 cycles per minute, P = 0.036) and a smaller peak tidal volume response to passive knee movement than controls. Ventilation, heart rate, stroke volume, and cardiac output peak responses, and total peripheral resistance nadir response, were unaltered by COPD. In addition, patients had a diminished glutathione ratio (COPD: 13.3 ± 3.8 vs controls: 20.0 ± 5.5 a.u., P = 0.015) and an augmented brain-derived neurotrophic factor expression (COPD: 2.0 ± 0.7 vs controls: 1.1 ± 0.4 a.u., P = 0.002) than controls. Prostaglandin E receptor 4, cyclooxygenase 2, and Piezo1 expression were similar between groups. Respiratory frequency response to mechanoreceptors activation is increased in patients with COPD. This abnormality is possibly linked to glutathione redox imbalance and augmented brain-derived neurotrophic factor expression within locomotor muscles, which could increase mechanically sensitive afferents' stimulation and sensitivity.

A Review of Flow Control for Gust Load Alleviation

Effective control of aerodynamic loads, such as maneuvering load and gust load, allows for reduced structural weight and therefore greater aerodynamic efficiency. After a basic introduction in the types of gusts and the current gust load control strategies for aircraft, we outline the conventional gust load alleviation techniques using trailing-edge flaps and spoilers. As these devices also function as high-lift devices or inflight speed brakes, they are often too heavy for high-frequency activations such as control surfaces. Non-conventional active control devices via fluidic actuators have attracted some attention recently from researchers to explore more effective gust load alleviation techniques against traditional flaps for future aircraft design. Research progress of flow control using fluidic actuators, including surface jet blowing and circulation control (CC) for gust load alleviation, is reviewed in detail here. Their load control capabilities in terms of lift force modulations are outlined and compared. Also reviewed are the flow control performances of these fluidic actuators under gust conditions. Experiments and numerical efforts indicated that both CC and surface jet blowing demonstrate fast response characteristics, capable for timely adaptive gust load controls.

Pseudointerpenetrating network nanocomposite hydrogel for temporary plugging in fractured reservoirs

Nanomaterial-enhanced hydrogels have attracted considerable attention as temporary plugging agents for lost circulation control due to their improved strength under high temperature and high pressure (HTHP) conditions compared to conventional hydrogels. In this study, a pseudointerpenetrating network nanocomposite hydrogel (PINNG), which was composed of temperature-resistant polyacrylamide (TSPAM), polyethyleneimine (PEI) and cellulose nanofibrils (CNFs), was proposed. CNF with a fibrous structure exhibited a more significant effect on the rheological behavior and mechanical strength of the hydrogel than nanosilica (nano-SiO2). The reversible CNF network endowed the gelant with increased zero-shear viscosity and significant thixotropy. Furthermore, the presence of CNF noticeably improved the strength of PINNG, and the elastic modulus of PINNG was 1232% greater than that of the blank sample. According to analyses of Fourier transform infrared spectroscopy (FTIR), thermogravimetry-derivative thermogravimetry (TG–DTG) and scanning electron microscopy (SEM), it can be deduced that the strengthening mechanism of CNF was mainly related to physical filling, physical crosslinking, and especially the formation of a pseudointerpenetrating network structure with the crosslinked polymer chains. Due to the strengthening effect of CNF, PINNG exhibited a better pressure-bearing performance than the blank sample and the nano-SiO2 composite sample under 140 °C for the core with 2 mm of fracture width. Additionally, the favorable degradability of the PINNG system demonstrated that PINNG exhibited great potential in the application of lost circulation control as a temporary plugging agent.

Effect of Multistage Circulation Control on Blade Aerodynamic Performance

To improve the low aerodynamic efficiency and reduce the high energy consumption of a single-stage circulation control wing, a multistage circulation control wing was designed. By combining force measurement and particle image velocimetry (PIV), the aerodynamic and flow-field characteristics of an aerofoil were investigated with respect to the increase in the number of blowing slots, changes in the blowing coefficient, and different blowing ratios for three slots. The force measurement results revealed that the maximum lift-to-drag ratio resulting from simultaneous blowing into the three slots increased by 95.3% compared with that in the absence of circulation control. With an increase in the blowing coefficient, two stages were observed: separation control and supercirculation control. In the separation control stage, the lift and drag coefficients significantly increased and decreased, respectively. In the supercirculation control stage, the lift coefficient gradually increased with the blowing coefficient, whereas the drag coefficient remained unchanged. When the blowing ratio (blowing flow ratio of three slots) in the three slots was 3:1:2, the maximum lift-to-drag ratio of the wing could reach 143.48%. The effects of different slot positions on the aerodynamic control were found to vary. The effects of Slot.1 and Slot.3 in terms of the drag reduction and lift, respectively, were evident, and the influence of Slot.2 on blowing between these two slots played a role in jet relay. The PIV results revealed that multistage blowing circulation increased the curvature of the trailing-edge streamline, thus increasing the equivalent aerofoil camber and improving the wing lift. At a high angle of attack, this circulation demonstrated a flow separation control effect.

Polymer Gels Used in Oil-Gas Drilling and Production Engineering.

Polymer gels are widely used in oil–gas drilling and production engineering for the purposes of conformance control, water shutoff, fracturing, lost circulation control, etc. Here, the progress in research on three kinds of polymer gels, including the in situ crosslinked polymer gel, the pre-crosslinked polymer gel and the physically crosslinked polymer gel, are systematically reviewed in terms of the gel compositions, crosslinking principles and properties. Moreover, the advantages and disadvantages of the three kinds of polymer gels are also comparatively discussed. The types, characteristics and action mechanisms of the polymer gels used in oil-gas drilling and production engineering are systematically analyzed. Depending on the crosslinking mechanism, in situ crosslinked polymer gels can be divided into free-radical-based monomer crosslinked gels, ionic-bond-based metal cross-linked gels and covalent-bond-based organic crosslinked gels. Surface crosslinked polymer gels are divided into two types based on their size and gel particle preparation method, including pre-crosslinked gel particles and polymer gel microspheres. Physically crosslinked polymer gels are mainly divided into hydrogen-bonded gels, hydrophobic association gels and electrostatic interaction gels depending on the application conditions of the oil–gas drilling and production engineering processes. In the field of oil–gas drilling engineering, the polymer gels are mainly used as drilling fluids, plugging agents and lost circulation materials, and polymer gels are an important material that are utilized for profile control, water shutoff, chemical flooding and fracturing. Finally, the research potential of polymer gels in oil–gas drilling and production engineering is proposed. The temperature resistance, salinity resistance, gelation strength and environmental friendliness of polymer gels should be further improved in order to meet the future technical requirements of oil–gas drilling and production.

Post-occupancy evaluation and codesign in mental healthcare buildings: User’s input as a driver for functional and technical adaptations in post COVID-19 reality

During the COVID-19 pandemic, social distancing protocols imposed the suspension of many activities in mental healthcare facilities, limiting the use of the facility to people in comprehensive care. With the advancement of vaccination, these buildings are gradually reopening for community use. However, managers and workers now face challenges in accommodating new design demands related to reducing the risk of contamination by COVID-19 within the building. This research adopted a multi-method approach in two phases, combining a post-occupancy evaluation with a cocreation activity to help mental healthcare workers and patients to suggest design changes in their environment. Three Psychosocial Care Centers (CAPS) in São Paulo were selected as case-study buildings. The first phase was the Post-Occupancy Evaluation (POE), in which the lead researcher conducted a walkthrough with the facility administrator, applied questionnaires to 100 employees, and conducted a walking interview with 12 patients. During Phase 02, a codesign activity entitled “Dream CAPS” was conducted with 25 healthcare workers and 12 patients. In this activity, participants were asked to customize a physical model of a mental healthcare facility, choosing the wall and floor finishings, the types of openings (windows, doors), furniture, and ornaments. Afterward, they participated in an interview with illustrated cards. All activities were audio-recorded and textual analysis qualified and categorized the content. Objective and subjective data analysis identified five characteristics of the built environment that prevented or increased risk of COVID-19 spread: Places that support risk mitigation procedures, access and circulation control, extended use of outdoor spaces, natural and artificial air renovation systems, and materials resistant to terminal cleaning. Patients participated in the activities but did not express opinions on the impact of architecture on airborne disease prevention. Healthcare workers claimed that environments that improve mental health must be attractive and prone to social interaction and relaxation without compromising biological safety. The combination of post-occupancy evaluation and codesign proved an excellent tool to identify the demands of mental healthcare buildings and discuss the solutions that must be implemented to deal with contemporary and future crises in a pandemic context.

Smart Fluids and Their Applications in Drilling Fluids to Meet Drilling Technical Challenges

This article presents extensive analysis and review on recent developments in smart fluids as well as future opportunities of smart drilling fluids utilization in oil and gas well drilling while focusing on the following smart fluids: smart nanoparticles, electrorheological, magnetorheological, and viscoelastic surfactant (VES) fluids. The distinctive properties of nanoparticles such as tiny particle sizes, high specific surface area, mechanical strength, and thermal stability make them suitable for utilization in drilling fluids. In bentonite water-based drilling fluid systems, this review suggests that charged nanoparticles are capable of displacing exchangeable ions in between bentonite clay platelets, thereby forming intercalates which can interact with clay surfaces through electrostatic attraction or repulsion. In improving wellbore stability, it is presented in this review that nanoparticles are able to invade and plug ultratiny pore spaces in shale formations, thereby further enhancing shale formations’ mechanical strength and wellbore stability. According to this review, the magnitude of changes in properties of smart electrorheological and magnetorheological fluids largely depends on the intensity of applied electric and magnetic fields. The intensity of smart fluids properties alteration due to applied field would equally depend on wt.% concentration and chemical compositions of particles susceptible to electric and magnetic fields. Based on review carried out on VES smart fluids, attractive and repulsive forces in the smart VES fluids solution result in the formation of micelles which can cause changes in viscoelastic property of the formulated smart viscoelastic fluids. The more the concentration of charged ions in the base fluid which VES fluids come in contact with, the higher the viscoelasticity of the smart VES fluids. According to this review, utilization of smart materials in drilling fluids can result in meeting oil and gas well drilling technical challenges including enhancing wellbore stability, improving hole cleaning performance, lost circulation control, fluid loss control, enhancing rate of penetration, pressure drop control, and easing cutting carrying efficiency of drilling fluids. This review equally suggests that the utilization of smart fluids such as smart magnetorheological and electrorheological fluids would facilitate drilling automation and real-time data acquisition processes, which is the future technology in oil and gas drilling.

Vasovagal Syncope Is Associated with Variants in Genes Involved in Neurohumoral Signaling Pathways.

Vasovagal syncope (VVS) is the most common cause of sudden loss of consciousness. VVS results from cerebral hypoperfusion, due to abnormal autonomic control of blood circulation, leading to arterial hypotension. It is a complex disease, and its development is largely associated with genetic susceptibility. Since abnormal neurohumoral regulation plays an important role in VVS development, we analyzed the association of VVS with polymorphic variants of ADRA1A, ADRB1, HTR1A, ADORA2A, COMT, and NOS3 genes, the products of which are involved in neurohumoral signaling, in patients with a confirmed VVS diagnosis (157 subjects) and individuals without a history of syncope (161 subjects). We were able to identify the associations between VVS and alleles/genotypes ADRA1A rs1048101, ADRB1 rs1801253, ADORA2A rs5751876, and COMT rs4680, as well as NOS3 rs2070744 in biallelic combination with COMT rs4680. Thus, we are the first to observe, within a single study, the role of the genes that encode α- and β-adrenergic receptors, catechol-O-methyltransferase, adenosine receptors and nitric oxide synthase in VVS development. These findings demonstrate that the genes involved in neurohumoral signaling pathways contribute to the formation of a genetic susceptibility to VVS.

Directional couplings between the respiration and parasympathetic control of the heart rate during sleep and wakefulness in healthy subjects at different ages.

Cardiorespiratory interactions are important, both for understanding the fundamental processes of functioning of the human body and for development of methods for diagnostics of various pathologies. The properties of cardiorespiratory interaction are determined by the processes of autonomic control of blood circulation, which are modulated by the higher nervous activity. We study the directional couplings between the respiration and the process of parasympathetic control of the heart rate in the awake state and different stages of sleep in 96 healthy subjects from different age groups. The detection of directional couplings is carried out using the method of phase dynamics modeling applied to experimental RR-intervals and the signal of respiration. We reveal the presence of bidirectional couplings between the studied processes in all age groups. Our results show that the coupling from respiration to the process of parasympathetic control of the heart rate is stronger than the coupling in the opposite direction. The difference in the strength of bidirectional couplings between the considered processes is most pronounced in deep sleep.

Experimental study on the controlling factors of frictional coefficient for lost circulation control and formation damage prevention in deep fractured tight reservoir

Working fluids loss is a major contributor to low productivity during production process of fractured tight reservoirs. Lost circulation control effect directly related to the tribological behavior between fracture surface and lost circulation materials (LCMs). In this study, the friction coefficient (FC) was investigated using typical clastic rocks and LCMs by considering multiple effect factors divided into external condition and internal condition. The results show that normal load had a relatively high effect on sliding model. A positive correlation was observed between FC and asperities heights. FC decreased induced by particle size degradation of rigid LCMs. Elastic LCMs manifested higher FC compared with rigid LCMs. Under the lubrication condition by working fluid, FC of rigid LCMs was mainly controlled by their surface wettability. FC of organic LCMs is more sensitive to high temperature aging than inorganic LCMs. Fracture plugging experiments show that LCMs optimized based on the research results can effectively improve the efficiency and strength of fracture plugging. • Friction coefficient tests between the fracture surface and LCMs. • The influence of multiple effect factors on the friction behavior between the fracture surface and LCMs. • The optimization of loss control formula based on laboratory experiments.

Numerical Simulation of Ground Effect on Circulation Control Airfoil

Circulation control (CC) is used extensively to control the attitude of rudderless aircraft experiencing ground effect in take-off and landing phases. The investigation of ground effect on airfoil CC is necessary to improve flight performance and quality in proximity to the ground. The aerodynamics and flow field of a modified NACA0012 airfoil with CC in ground effect are investigated with numerical simulations. The compressible Reynolds-averaged Navier–Stokes equations with the shear-stress transport k − ω turbulence model equations are solved using the Finite Volume Method (FVM). Simulation results show that the ground effect changes the lift increment per unit jet momentum coefficient, and CC can reverse the polarity ground effect. The effective angle of attack α E and the downwash space downstream airfoil are altered by the ground effect resulting in variations of airfoil surface pressure and lift. Unlike the unbounded flow field, the jet attachment distance is not only determined by the jet momentum coefficient but it can change with the ride height, which is the distance from the ground to the center of the semicircular Coanda surface, for the same jet momentum coefficient.

Short-takeoff marine vehicle with circulation flow control of wing-in-ground effect

The concept of active circulation control has been proposed to improve lifting performance for various applications. It is mostly suggested as a flow control system to replace or minimize mechanical flaps or as a boundary layer control mechanism in the aerospace industry. The efficiency of these systems has always been the main concern due to increased drag and pumping requirements. These concerns are negligible for high-speed marine crafts as the hydrodynamic drag acting on the hull is dominant. This research investigates the aerodynamic performance of a NACA 4412 airfoil that was modified for circulation control to determine the influence of the trailing-edge geometry, blowing coefficient, angle of attack, and height above the ground to improve the efficiency of a wing-in-ground craft and shorten its take-off distance. The flow is subsonic and incompressible, and the chord Reynolds number is 1.7 × 106. A computational fluid dynamics investigation has determined that significant increases in lift can be attained through circulation control relative to the original NACA 4412 airfoil, and it is not significantly influenced by the airfoil height except when there is an extreme ground effect. Also, the lift augmentation increases approximately linearly with the blowing momentum coefficient and angle of attack. The study shows a significant improvement in the take-off length, which was reduced from 465 m to between 360 and 150 m according to the height above the ground plane, angle of attack, and the momentum coefficient when the Coanda surface is 30 mm. The circulation-controlled NACA 4412 could achieve 66% effectiveness compared to a currently available vehicle.

Research on the roll control of the flapless aircraft with circulation control

The purpose of this paper is to study the roll control of the flapless aircraft under low-speed and high-speed flight states and investigate the equivalent control effect (ECE) and the power consumption of the pneumatic control. First, the roll moment coefficient of the aircraft with different aileron deflection angles is calculated. Then the intensity of the jet is adjusted to match the roll moment coefficient, so that the deflection angle of the ailerons and the intensity of the jet corresponding to the same rolling moment are found. Based on the realization of the roll control, the aerodynamic efficiency of the flapless aircraft is evaluated by using the equivalent lift-to-drag ratio ( Ecc) considering power consumption. The ECE curves of the pneumatic roll control under low-speed and high-speed flight states are obtained. Under low-speed flight state, the increment of aerodynamic efficiency brought by the jet cannot make up for its power consumption. Under high-speed flight state, the aerodynamic efficiency increment brought by the pneumatic control can compensate its power consumption before Cl = 0.061.