High Tortuosity Research Articles

Continuous Liquid-Liquid Extraction and in-Situ Membrane Separation of Miscible Liquid Mixtures.

Separation operations are critical across a wide variety of manufacturing industries and account for about one-quarter of all in-plant energy consumption in the United States. Conventional liquid-liquid separation operations require either thermal or chemical treatment, both of which have a large environmental impact and carbon footprint. Consequently, there is a great need to develop sustainable, clean methodologies for separation of miscible liquid mixtures. The greatest opportunities to achieve this lie in replacing high-energy separation operations (e.g., distillation) with low-energy alternatives such as liquid-liquid extraction. One of the primary design challenges in liquid-liquid extraction is to maximize the interfacial area between two immiscible (e.g., polar and nonpolar) liquids for efficient mass transfer. However, this often involves energy-intensive methods including ultrasonication, pumping the feed and the extractant through packed columns with high tortuosity, or using a supercritical fluid as an extractant. Emulsifying the feed and the extractant, especially with a surfactant, offers a large interfacial area, but subsequent separation of emulsions can be energy-intensive and expensive. Thus, emulsions are typically avoided in conventional extraction operations. Herein, we discuss a novel, easily scalable, platform separation methodology termed CLEANS (continuous liquid-liquid extraction and in-situ membrane separation). CLEANS integrates emulsion-enhanced extraction with continuous, gravity-driven, membrane-based separation of emulsions into a single unit operation. Our results demonstrate that the addition of a surfactant and emulsification significantly enhance extraction (by >250% in certain cases), even for systems where the best extractants for miscible liquid mixtures are known. Utilizing the CLEANS methodology, we demonstrate continuous separation of a wide range of miscible liquid mixtures, including soluble organic molecules from oils, alcohols from esters, and even azeotropes.

Carotid Geometry and Wall Shear Stress Independently Predict Increased Wall Thickness-A Longitudinal 3D MRI Study in High-Risk Patients.

Introduction: Carotid geometry and wall shear stress (WSS) have been proposed as independent risk factors for the progression of carotid atherosclerosis, but this has not yet been demonstrated in larger longitudinal studies. Therefore, we investigated the impact of these biomarkers on carotid wall thickness in patients with high cardiovascular risk.Methods: Ninety-seven consecutive patients with hypertension, at least one additional cardiovascular risk factor and internal carotid artery (ICA) plaques (wall thickness ≥ 1.5 mm and degree of stenosis ≤ 50%) were prospectively included. They underwent high-resolution 3D multi-contrast and 4D flow MRI at 3 Tesla both at baseline and follow-up. Geometry (ICA/common carotid artery (CCA)-diameter ratio, bifurcation angle, tortuosity and wall thickness) and hemodynamics [WSS, oscillatory shear index (OSI)] of both carotid bifurcations were measured at baseline. Their predictive value for changes of wall thickness 12 months later was calculated using linear regression analysis for the entire study cohort (group 1, 97 patients) and after excluding patients with ICA stenosis ≥10% to rule out relevant inward remodeling (group 2, 61 patients).Results: In group 1, only tortuosity at baseline was independently associated with carotid wall thickness at follow-up (regression coefficient = −0.52, p < 0.001). However, after excluding patients with ICA stenosis ≥10% in group 2, both ICA/CCA-ratio (0.49, p < 0.001), bifurcation angle (0.04, p = 0.001), tortuosity (−0.30, p = 0.040), and WSS (−0.03, p = 0.010) at baseline were independently associated with changes of carotid wall thickness at follow-up.Conclusions: A large ICA bulb and bifurcation angle and low WSS seem to be independent risk factors for the progression of carotid atherosclerosis in the absence of ICA stenosis. By contrast, a high carotid tortuosity seems to be protective both in patients without and with ICA stenosis. These biomarkers may be helpful for the identification of patients who are at particular risk of wall thickness progression and who may benefit from intensified monitoring and treatment.

Optimizing the Packing Density and Chemistry of Cellulose Nanofilters for High-Efficiency Particulate Removal

The global spread of COVID-19 as well as the worsening air pollution throughout the world have brought tremendous attention to the development of materials that can efficiently capture particulate matter. We suggest that the high porosity of electrospun filters composed of nanofibers could provide minimal obstruction to air flow, while their high tortuosity and surface area-to-volume ratio present an excellent platform to capture particulates. In this study, the removal of nanoscale particles via in-house fabricated cellulose nanofilters is significantly enhanced by chemically functionalizing the fibers’ surface via the deposition of the bioinspired glue polydopamine (PDA) or the polycation poly(diallyldimethylammonium chloride) (PDADMAC). The effects of filter packing density, layering thickness, and chemistry on their performance, i.e., their filtration efficiency, most penetrating particle size (MPPS), particle fractional penetration percent, and performance in a high relative humidity environment, were investigated. When evaluated in an extremely hazardous environment (PM concentration ∼ 2000 μg m–3), the filtration efficiency, pressure drop, and quality factor for the cellulose nanofilters were measured to be >98.0%, <200 Pa, and ∼0.03 Pa–1, respectively. When we evaluated the performance of a composite hydrophobic/hydrophilic filter in an 80% relative humidity environment, a 99.8% filtration efficiency was achieved. We have demonstrated that the removal of nanoscale particulates can be effectively captured using cellulose-based nanofilters, even in a nonideal high humidity environment. These fundamental investigations into the structure–property-chemistry relationships of in-house electrospun nanofilters on nanoscale particulate removal hold the potential to help drive the future engineering of nanofilters for air purification applications, which is a timely and extremely important concern.

Transport In and Optimization of Aligned-Channel Li-Ion Electrode Architectures

Advanced electrode architectures utilizing aligned channels show promise in improving rate performance. However, the relationship between aligned channel structure and electrode-scale ion transport rate must be understood to enable optimization of electrode designs. Using a physics-based P2D model for experimental analysis, the impact of aligned channel electrode structures on cell rate capability is quantified. Results are used for optimization of aligned-channel volume fraction and electrode mass loading. Anticipated improvements in volumetric energy density over optimal for conventional, slurry-cast electrodes are shown to be significant at high rates and with electrodes characterized by high tortuosity.

Aortic Geometric Alteration Associated With Acute Type B Aortic Dissection: Angulation, Tortuosity, and Arch Type.

Background: Acute type B aortic dissection is a highly serious aortic pathology. Aortic geometric parameters may be useful variables related to the occurrence of acute type B aortic dissection (aTBAD). The aim of the study is to delineate the alteration in aortic geometric parameters and analyze the specific geometric factors associated with aTBAD.Methods: The propensity score matching method was applied to control confounding factors. The aortic diameter, length, angulation, tortuosity, and type of aortic arch of the aTBAD and control group were retrospectively analyzed via three-dimensional computed tomography imaging created by the 3mensio software (version 10.0, Maastricht, The Netherlands). The geometric variables of true lumen and false lumen in the descending aorta were measured to estimate the severity of aortic dissection. Multivariable logistic regression models were used to investigate the significant and specific factors associated with aTBAD occurrence. The area under the receiver operating characteristic curve (AUC) was used to estimate the performance of the model.Results: After propensity score matching, 168 matched pairs of patients were selected. The ascending aorta and aortic arch diameters were dilated, and the ascending aorta and total aorta lengths were elongated in aTBAD group significantly (P < 0.001). The ascending aorta and aortic arch angulations in the aTBAD group were sharper than those of the controls (P = 0.01, P < 0.001, respectively). The aortic arch and total aorta tortuosities were significantly higher in the aTBAD group (P = 0.001, P < 0.001, respectively). There were more type III arch patients in the aTBAD group than the controls (67.9 vs. 22.6%). The true lumen angulation was sharper than that in the false lumen (P < 0.01). The true lumen tortuosity was significantly lower than that in the false lumen (P < 0.001). The multivariable models identified that aortic arch angulation, tortuosity, and type III arch were independent and specific geometric factors associated with aTBAD occurrence. The AUC of the multivariable models 1, 2, 3 were 0.945, 0.953, and 0.96, respectively.Conclusions: The sharper angulation and higher tortuosity of aortic arch and type III arch were the geometric factors associated with aTBAD in addition to the ascending aorta elongation and aortic arch dilation. The angulation and tortuosity of the true and false lumens may carry significant clinical implications for the treatment and prognosis of aTBAD.

Electrospun nanofiber based forward osmosis membrane using graphene oxide as substrate modifier for enhanced water flux and rejection performance

Electrospun nanofiber (ENs) membranes with advantages of high porosity and low tortuosity have been considered as the ideal forward osmosis (FO) substrates for the effective mitigation of internal concentration polarization (ICP). However, the rough surface and large surface pores of ENs substrates may have adverse effects on the properties of the polyamide (PA) active layer. In this study, graphene oxide (GO) nanosheet was chosen as the modifier to adjust the characteristics of polyacrylonitrile (PAN) ENs substrate. The structure and properties (e.g., osmotic flux and specific salt flux) of the PA active layer was found be effectively tailored by the GO loading density. The appropriate loading of GO nanosheets might retard the penetration of polyamide into the substrate surface pores and meanwhile enhance the cross-linking degree of the PA active layer, resulting in the improvement of water flux and salt rejection. The optimized FO membrane (TFC-GO2) could achieve a higher water flux (32.7 g/m2·h) and lower specific salt flux (0.26 g/L) than the control membrane (TFC-0) in the FO mode. The appropriate loading of GO nanosheets on ENs substrates was proven to be a competitive strategy for developing high-performance ENs based FO membranes.

Wood‐Inspired Binder Enabled Vertical 3D Printing of g‐C3N4/CNT Arrays for Highly Efficient Photoelectrochemical Hydrogen Evolution

Abstract2D nanomaterials are very attractive for photoelectrochemical applications due to their ultra‐thin structure, excellent physicochemical properties of large surface‐area‐to‐volume ratios, and the resulting abundant active sites and high charge transport capacity. However, the application of commonly used 2D nanomaterials with disordered‐stacking is always limited by high photoelectrode tortuosity, few surface‐active sites, and low mass transfer efficiency. Herein, inspired by wood structures, a vertical 3D printing strategy is developed to rapidly build vertically aligned and hierarchically porous graphitic carbon nitride/carbon nanotube (g‐C3N4/CNT) arrays by using lignin as a binder for efficient photoelectrochemical hydrogen evolution. Arising from the directional electron transport and multiple light scattering in the out‐of‐plane aligned and porous architecture, the resulting g‐C3N4/CNT arrays display an outstanding hydrogen evolution performance, with the hydrogen yield up to 4.36 µmol (cm−2 h−1) at a bias of −0.5 V versus RHE, 12.7 and 41.6 times higher than traditional thick g‐C3N4/CNT and g‐C3N4 films, respectively. Moreover, this 3D printed structure can overcome the agglomeration problem of the commonly used g‐C3N4 with powder configuration and shows desirable recyclability and stability. This facile and scalable vertical 3D printing strategy will open a new avenue to highly enhance the photoelectrochemical performance of 2D nanomaterials for sustainably production of clean energy.

Characteristics of Corneal Subbasal Nerves in Different Age Groups: An in vivo Confocal Microscopic Analysis.

PurposeTo determine the normative characteristics of corneal subbasal nerves in different age groups using laser scanning in vivo confocal microscopy (IVCM).Patients and MethodsThis descriptive observational study recruited healthy subjects (aged 20–60 years) from Siriraj Health-Screening Center. Excluded were individuals who had abnormal ocular symptoms, previous ocular surgery, a history of any diseases related to systemic and/or corneal neuropathy, or abnormal corneal sensitivity. Corneal IVCM (HRT3/Rostock Corneal Module) was performed at the central cornea to analyze the subbasal nerve plexus. The corneal nerve characteristics, comprising the number and density of nerves (main nerve trunks, branches, and total nerves) were analyzed using the NeuronJ program, and the corneal nerve tortuosity was graded. The correlations between the subbasal nerve density, tortuosity and age were then analyzed.ResultsEighty subjects were enrolled, with twenty in each of four age groups (20–30, >30–40, >40–50, and >50–60 years). Overall, the mean number and density of main nerve trunks were 27.93±0.81/mm2 and 11.22±0.30 mm/mm2, respectively. As of the nerve branches, the average number and density were 103.56±2.37/mm2 and 9.15±0.30 mm/mm2, respectively. The total nerve density was 20.37±0.39 mm/mm2. There were no significant differences between subbasal nerve parameters of the four age groups. It is noteworthy that 65% of the subjects aged over 40 years revealed high-grade nerve tortuosity.ConclusionThe corneal subbasal nerve numbers and densities were not significantly different among a healthy population aged 20–60 years. However, there was a trend towards high tortuosity of the corneal nerve in people aged over 40 years.

Janus membranes for fast-mass-transfer separation of viscous ionic liquids from emulsions

Separation membranes are urgently desired for the efficient recovery of oil-like ionic liquids (ILs) from industrially applied emulsions. Conventional membranes with asymmetric porous structure and high tortuosity suffer from high trans-membrane resistance and low mass transfer efficiency for this application. Herein, Janus membranes (JMs) are constructed by the single-side modification of hydrophobic poly(vinylidene fluoride) (PVDF) membrane with vertically penetrative pores for the rapid-mass-transfer separation of viscous ILs. A charged and underwater IL-phobic thin layer is facilely co-deposited on one side of the PVDF membranes from polydopamine/poly(diallyldimethylammonium chloride) solution. This single-side modification endows the as-prepared JMs with a deemulsification function to IL-in-water emulsions and a unidirectional transportation ability to hydrophobic ILs. These JMs show an excellent IL recovery capacity with high permeation speed and stable flux during a long-term cyclic separation of IL-in-water emulsions because the vertically penetrative pores with low tortuosity allow to significantly reduce the trans-membrane resistance toward those viscous ILs. Overall, our vertically-channeled JMs provide an ideal material solution for recovering high-viscosity and value-added chemicals from their industrial water mixture in practice, especially from those aqueous emulsions.

Perforative pore formation on nanoplates for 2D porous MXene membranes via H2O2 mild etching

MXene (Ti3C2Tx) is a novel, two-dimensional (2D) layered material that is atomically thin, exhibits good mechanical strength, and is ideal for fabricating efficient membranes for molecular separation. However, the applications of MXene membranes are limited by their low water permeability owing to narrow channels and high tortuosity. A novel strategy for introducing artificial pores on the surface of MXene nanosheets via gentle in situ chemical etching with hydrogen peroxide (H2O2) to prepare porous MXene nanosheets (PMS) is reported herein. This greatly increases the water permeability of MXene membranes while retaining the high rejection of small-molecule dyes. Permeable pores generated on MXene nanosheets transform the transport model of water molecules in the membrane from typical horizontal transport pathways dominated by interlayer channels to longitudinal–lateral three-dimensional transport pathways, affording increased water molecule transport channels and reduced transport distance. Based on different etching conditions, the obtained membranes exhibit high pure-water permeability ranging from 9.37 to 42.48 L m−2 h−1 bar−1. Moreover, mild etching maintains the 2D structure of the membrane and retains a nearly complete rejection of congo red dye. This study provides a novel and effective strategy for preparing high-performance porous laminar MXene membranes for dye-separation applications.

Janus hybrid sustainable all-cellulose nanofiber sponge for oil-water separation

Two-faced characteristics and performance of materials driven by asymmetric physical or chemical properties exist in Janus hybrid materials which show synergistic and improved properties for a variety of applications. Here, we report a facile synthesis of Janus hybrid sustainable cellulose nanofibers (CNFs) sponge with asymmetric wettability and strong mechanical property for excellent separation efficiency of oil-water emulsions. Briefly, the CNF Janus hybrid sponge was fabricated by freeze-drying of two separate CNF suspensions into one, each prepared separately by introducing CNFs in methyltrimethoxysilane (MTMS) or 3-glycidoxypropyltrimethoxysilane (GPTMS) for hydrophobic or hydrophilic performance, respectively. The sponge demonstrated satisfactory mechanical stability with an excellent recovery from 80% compressive strain and high pore tortuosity. When employed for oil-water separation, the Janus hybrid sponge could selectively be used to collect water or oil by just switching its side facing the oil-water mixture feed via unidirectional gravity-assisted separation, with recyclability. The fabrication of such Janus hybrid sponge is one of the many approaches for utilizing nanofibers in structurally adaptive, self-supported asymmetric membrane structures in a 3D network.

COMPARATIVE STUDY BETWEEN RADIAL AND ULNAR ARTERY ACCESS FOR CORONARY ANGIOGRAPHY AND FOR PERCUTANEOUS CORONARY INTERVENTION

Background: Transulnar approach had been suggested for elective procedures in patients not suitable for transradial approach. It is as safe and effective as the transradial approach for coronary angiography and intervention. Objective: To evaluate the safety and feasibility of percutaneous transulnar approach for coronary angiography and intervention. Patient and Methods: This study is a prospective study which was done in Cardiology department of Alazhar University Hospitals and National Heart Institute from the period of July 2019 to July 2020. One hundred patients requiring coronary angiography plus or minus intervention were enrolled and randomly assigned for 2 equal groups: Group I with radial access and Group II with ulnar access. Demographic and comparative analyses of both access sites were obtained. Results: Group II was notably older than Group I (60.9 ± 7.9 versus 57.7 ± 6.7, p= 0.029). There was no difference between the two groups concerning puncture time, number of attempts to fix the artery, procedure and fluoroscopy times. Procedural success rate in both groups was (96% versus 90% in group I and II respectively, p= 0.240) with similar frequency of acute complications as spasm, hematoma or hand ischemia. Vascular anomalies as high takeoff and tortuosities encountered more common in the radial as compared to ulnar group, however, did not reach statistical significance. Conclusion: Transulnar approach was as safe and feasible as transradial access for coronary procedures with similar technical tactic, success and complication rates. However, because of radial artery was more superficial, transulnar access was a realistic alternative to radial route whenever not attainable.

Mechanical and thermal properties of a biomimetic multi-layered carbon nanofibers 3D networks: A novel strategy for 3D finite element analysis modeling and simulation

Graphene-Coated carbon nanofibers (G-CNFs) Foams with interconnected 3D-networks have unique physical properties that make them suitable for a wide variety of applications. However, their design and fabrication strategies entail several parameters with different strengths, anisotropy, and thermal conductivity. Tuning functional properties to meet the desired application needs a deep understanding of their microstructure. Utilizing a microstructure modeling based on a Finite Element Analysis (FEA) requires adopting an accurate yet simple approach to overcome complications associated with the unique morphological characteristics of the G-CNFs Foam, covering graphene coating thickness and high aspect ratio and tortuosity, that can be neither disregarded nor roughly approximated. Here, we introduce an innovative strategy to predict the morphological, mechanical, and thermal properties of a G-CNFs Foam with a high aspect ratio and tortuosity, as well as a significant difference in composite materials' strength to overcome modeling difficulties including meshing, coating thickness, and homogenization, to name a few. This new modeling strategy is validated with experimental data from our work and the literature and provides a reliable and straightforward approach with less computational cost.

Tough-Hydrogel Reinforced Low-Tortuosity Conductive Networks for Stretchable and High-Performance Supercapacitors.

All-solid-state supercapacitors are seeing emerging applications in flexible and stretchable electronics. Supercapacitors with high capacitance, high power density, simple form factor, and good mechanical robustness are highly desired, which demands electrode materials with high surface area, high mass loading, good conductivity, larger thickness, low tortuosity, and high toughness. However, it has been challenging to simultaneously realize them in a single material. By compositing a superficial layer of tough hydrogel on conductive and low tortuous foams, a thick capacitor electrode with large capacitance (5.25 F cm-2 ), high power density (41.28mW cm-2 ), and good mechanical robustness (ε= 140%, Γ= 1000 J m-2 ) is achieved. The tough hydrogel serves as both a load-bearing layer to maintain structural integrity during deformation and a permeable binder to allow interaction between the conductive electrode and electrolyte. It is shown that the tough hydrogel reinforcement is beneficial for both electrical and mechanical stability. With a simple design and facile fabrication, this strategy is generalizable for various conductive materials.

The Potential of AFX Iliac Extension in Abdominal Aortic Aneurysms with High Iliac Tortuosity.

Recently, endovascular aortic aneurysm repair (EVAR) is the most common surgery for abdominal aortic aneurysm (AAA). However, iliac limb complications of EVAR often cause problems in patients with high iliac tortuosity. There is no difference of rate of iliac limb complication among EVAR devices, such as Excluder, Endurant, and Zenith in high iliac tortuosity. But there has been not reported about AFX. We studied AFX iliac extension as it is the only stent graft with an endoskeletal framework. This study aimed to evaluate the AFX iliac extension patency in a case in vitro and to use it in seven cases of AAA with high iliac tortuosity. The silicon tube inserted in the AFX iliac extension was flexed at 30, 60, 90, and 120 degrees, and the lumen of the iliac extension was monitored using an underwater camera in the circulatory system. During the experiment, the Iwaki Bellows Pump (IWAKI CO., LTD., Tokyo, Japan) produced a pulsating flow. We used this in seven patients with AAA high iliac tortuosity cases between November 2018 and May 2019. If the silicon tube inserted in the AFX iliac extension was flexed at 60 and 120 degrees, the stent protruded into the lumen. However, the graft was dilated at all degrees. All seven patients with AFX iliac extension had no complications and a patent iliac artery. The AFX iliac extension can reduce iliac limb complications in cases of high iliac tortuosity.

Mapping the transcriptomic changes of endothelial compartment in human hippocampus across aging and mild cognitive impairment.

ABSTRACTCompromise of the vascular system has important consequences on cognitive abilities and neurodegeneration. The identification of the main molecular signatures present in the blood vessels of human hippocampus could provide the basis to understand and tackle these pathologies. As direct vascular experimentation in hippocampus is problematic, we achieved this information by computationally disaggregating publicly available whole microarrays data of human hippocampal homogenates. Three conditions were analyzed: ‘Young Adults’, ‘Aged’, and ‘aged with Mild Cognitive Impairment’ (MCI). The genes identified were contrasted against two independent data-sets. Here we show that the endothelial cells from the Younger Group appeared in an ‘activated stage’. In turn, in the Aged Group, the endothelial cells showed a significant loss of response to shear stress, changes in cell adhesion molecules, increased inflammation, brain-insulin resistance, lipidic alterations, and changes in the extracellular matrix. Some specific changes in the MCI group were also detected. Noticeably, in this study the features arisen from the Aged Group (high tortuosity, increased bifurcations, and smooth muscle proliferation), pose the need for further experimental verification to discern between the occurrence of arteriogenesis and/or vascular remodeling by capillary arterialization. This article has an associated First Person interview with the first author of the paper.

Numerical investigation on the influence of micropore structure characteristics on gas seepage in coal with lattice Boltzmann method

The micropore structure of coal has a significant impact on gas seepage in a coal reservoir. In this study, the micropore structure of coal was reconstructed and then quantitatively analysed using independently developed image analysis software. The lattice Boltzmann method (LBM) at representative elementary volume (REV) scale was used on the reconstructed pore structure to simulate gas seepage and obtain the gas velocity distribution. The effects of porosity and pore structure on gas seepage were studied. The results indicated that gas seepage velocity and apparent permeability increase with porosity. The average gas seepage velocity in the pore structure with >25% porosity was more than two-fold that in the pore structure with <25% porosity, and apparent permeability increased by at least three orders of magnitude. The gas seepage velocity in open-pore areas was higher than that in closed-pore areas and highest in through holes, followed by semi-through holes and closed pores. The gas seepage velocity was higher in long and narrow pore structures and reached a maximum along the centre line of the pore throat. The non-main flow areas of gas appeared in through holes that had noticeable shrinkage, expansion, and high tortuosity, causing gas accumulation in the coal body.

Anatomic features in SCAD assessed by CCT: A propensity score matching case control study

PurposeSpontaneous coronary artery dissection (SCAD) may occur in middle age population without any cardiovascular risk factor. We retrospectively evaluated anatomic features of 11 patients with SCAD using a coronary arteries computed tomography (CCT), compared to age and sex balanced patients who underwent CCT. Material and methodsCCT was performed in 11 patients (7 females and 4 males) as follow-up in patients with SCAD (left anterior descending – LAD or circumflex artery – Cx) and compared, using the propensity score matching analysis, with 11 healthy patients. Several anatomic features were evaluated: Left main (LM) length, angle between descending coronary artery (LAD) and its first branch, angle between LAD and LM, distance from the annulus to RCA (a-RCA distance) and LM (a-LM distance) ostia and their ratio; ratio between LM length and length a-LM and tortuosity score of the vessel with SCAD. A fluid dynamic analysis has been performed to evaluate the effects on shear stress of vessels wall. ResultsLM length was significantly shorter in patients with SCAD versus healthy subjects (P=0.01) as well as LM length/a-LM (P=0.03) and the angle between LAD and the first adjacent branch was sharper (P<0.01). Tortuosity score showed a statistically significant difference between groups (P<0.001). Fluid dynamic analysis demonstrates that, in SCAD group, an angle<90 degree is present at the first bifurcation and it can be a cause of increased strain on vessel wall in patients with high tortuosity of coronary artery. ConclusionTortuosity and angle between the LAD and the adjacent arterial branch combined may determine increased shear stress on the vessel wall that increases the risk of SCAD.

Technology Focus: Extended-Reach and Complex Wells (May 2021)

In selecting papers for this feature, reviewer Stéphane Menand of Helmerich and Payne has identified a trio of papers that investigates new approaches toward familiar issues encountered when drilling complex well types. Whether considering the customization of drilling approaches in Middle Eastern carbonate reservoirs, implementing a collaborative work flow in tackling high-tortuosity wells offshore Western Australia, or researching the ability of a fibrous material to effect hole cleaning as opposed to polymeric sweeps, the authors of these papers understand that technical expertise may not be completely realized if it is not applied to problems in original ways. In carbonate reservoirs, the goal of drilling extended-reach wells is set against the geological makeup of such formations, the complexity of which adds significant uncertainty to geosteering and well placement. The authors of paper SPE 203335 develop a work flow that makes possible the customization of drilling scenarios through an emphasis on mechanical specific energy, as well as the use of an optimized borehole-assembly design. The work flow helped deliver what the authors write is the longest well in the Middle East offshore Abu Dhabi. In a similar vein, the authors of paper SPE 202251 describe a challenging scenario involving an ultraextended-reach well in a mature field offshore Western Australia. The project overcame shallow water depth and a high tortuosity requirement by implementing an integrated plan that used a reservoir-mapping-while-drilling service. The authors stress that this technology, coupled with active collaboration between specialists, town, and rig site, allowed the project to achieve the desired oil-column thickness with zero collision incidents. Highly deviated wells often face problems resulting from ineffective hole cleaning. Paper SPE 203147 studies the properties of a fibrous material when compared with the hole-cleaning performance of common polymeric pills. The authors write that the fibrous material proved effective, in part because of a unique characteristic in which a spiderweb-like network of fibers is created that does not allow cuttings to settle easily in complex wells. In addition, the material is environmentally friendly. All three papers approach well- established problems in the critical industry sector of extended-reach drilling with innovation and confidence. Enjoy the papers and be sure to search SPE’s OnePetro online library for more fresh approaches to the technical challenges posed by these well types. Recommended additional reading at OnePetro: www.onepetro.org. SPE 196410 - Analysis of Friction-Reduction System During Drilling Operation at a High-Inclination Well on Field X by Rizqiana Mudhoffar, Tanri Abeng University, et al. SPE 197257 - Successful Management of Collision Risk in an Extended-Reach Well by Manchukarn Naknaka, Mubadala Petroleum, et al. SPE 202730 - Challenges in Drilling and Completion of Extended-Reach-Drilling Wells With Landing Point Departure of More Than 10,000 ft in Light/Slim Casing Design by Nitheesh Kumar Unnikrishnan, Abu Dhabi National Oil Company, et al.

Collaboration and Optimization Processes Contribute to Ultra-ERD Offshore Well Success

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 202251, “Transforming the Mindset To Drill Ultra-ERD Wells With High Tortuosity,” by Barry Goodin, SPE, Duane Selman, and Andy Wroth, Vermilion Oil and Gas, et al., prepared for the 2020 SPE Asia Pacific Oil and Gas Conference and Exhibition, originally scheduled to be held in Perth, Australia, 20–22 October. The paper has not been peer reviewed. The complete paper describes the extensive integrated engineering collaboration and optimization process that allowed an operator to push the drilling and completion envelope to drill a pair of complex, ultra-extended-reach-drilling (ERD) wells in the mature Wandoo field in the Carnarvon Basin offshore Western Australia. The shallow reservoir depth, extreme ERD profile, and high tortuosity requirement for the wells posed significant challenges. These were overcome with extensive planning; integrated engineering designs; application of new technology; good-quality, real-time data interpretation; and strong execution support from both rig site and town. Introduction The Wandoo field, in 56 m of water off-shore Western Australia, was discovered in 1991 and subsequently developed and placed on production in 1993. The shallow unconsolidated sandstone reservoir consists of a heavily biodegraded oil column overlain by a gas cap and supported by a strong aquifer drive. Field infrastructure consists of a 15-well-slot manned production facility, Wandoo B, and a five-slot monopod, Wandoo A, which is tied back to Wandoo B by subsea in-field pipelines. In late 2018, the operator planned and executed a two-well drilling campaign consisting of two complex, ultra-ERD wells, Wandoo B15 and B16. Both wells were planned to be batch drilled for the top hole and intermediate hole sections, with the production hole sections to be drilled and completed sequentially. The primary objective for the B15 well was to recover unswept oil along the western flank of the field and track the well along the main Wandoo fault to the north to assess the structure and reserves from the northern tip of the field. The B16 well objective was to access unswept reserves through the center and down to the south of the field, essentially twinning the B11ST1 well, another ERD well drilled on an earlier campaign, to its eastern flank. To maximize recovery, both wells needed to be placed approximately 1 m below the top of the reservoir, except where overlain by the gas cap, in which case the wells were to be placed approximately 2 m below the gas/oil contact to avoid gas coning. Drilling Challenges and Solutions The first half of the complete paper presents a detailed discussion of the drilling challenges and solutions, illustrated with schematics, maps, charts, and graphs. Both Wells B15 and B16 were classified as ultra-ERD wells because the shallow true vertical depth (TVD) of the reservoir resulted in extreme stepout ratios and required highly complex well paths to access the remaining reserves. The complete paper lists various specific drilling- and systems-related challenges.