Application of the Quemada Viscosity Model for Drilling Fluids

2021 ◽  
Author(s):  
Sandra Knutsen ◽  
Eric Cayeux ◽  
Arild Saasen ◽  
Mahmoud Khalifeh
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Drilling Fluid ◽  
Model Fit ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Rate Dependent ◽  
Dependent Viscosity ◽  
Very High

Abstract A number of different models are used to describe the shear rate dependent viscosity of drilling fluids. Most, such as the Herschel-Bulkley model, have a purely empirical basis. The Quemada model, while still empirical, is based on physical principles. It is based on the notion that structural units develop in the fluid at low shear rates which are then partially broken down as the applied shear rate increases. In the current work, drilling fluid rheological data are fitted to the Herschel-Bulkley and the Quemada model. The development of the Quemada model and the calculation of each model parameter are presented. We show that the Quemada model better fits measurements over a wider range of shear rates than the Herschel-Bulkley model. We describe how to select the parameters of the Quemada model. Knowing the difficulty of obtaining a known shear rate for fluids with yield stresses, we discuss how this can affect the quality of the Quemada model fit. Furthermore, in principle, the Quemada model is not applicable in presence a non-zero yield stress. Therefore, we show how to handle the yield stress using a (very high) zero shear rate viscosity.

Characterization of the Rheological Behavior of Drilling Fluids

2020 ◽  
Author(s):  
Eric Cayeux ◽  
Amare Leulseged
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Operation Conditions ◽  
Fluid Systems ◽  
Different Temperatures ◽  
The One ◽  
Shear Stress Response

Abstract It is nowadays well accepted that the steady state rheological behavior of drilling fluids must be modelled by at least three parameters. One of the most often used models is the yield power law, also referred as the Herschel-Bulkley model. Other models have been proposed like the one from Robertson-Stiff, while other industries have used other three-parameter models such as the one from Heinz-Casson. Some studies have been made to compare the degree of agreement between different rheological models and rheometer measurements but in most cases, already published works have only used mechanical rheometers that have a limited number of speeds and precision. For this paper, we have taken measurements with a scientific rheometer in well-controlled conditions of temperature and evaporation, and for relevant shear rates that are representative to normally encountered drilling operation conditions. Care has been made to minimize the effect of thixotropy on measurements, as the shear stress response of drilling fluids depends on its shear history. Measurements have been made at different temperatures, for various drilling fluid systems (both water and oil-based), and with variable levels of solid contents. Also, the shear rate reported by the rheometer itself, is corrected to account for the fact that the rheometer estimates the wall shear rate on the assumption that the tested fluid is Newtonian. A measure of proximity between the measurements and a rheological model is defined, thereby allowing the ranking of different rheological behavior model candidates. Based on the 469 rheograms of various drilling fluids that have been analyzed, it appears that the Heinz-Casson model describes most accurately the rheological behavior of the fluid samples, followed by the model of Carreau, Herschel-Bulkley and Robertson-Stiff, in decreasing order of fidelity.

scholarly journals Viscosity Models for Drilling Fluids—Herschel-Bulkley Parameters and Their Use

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5271 ◽  
Author(s):  
Arild Saasen ◽  
Jan David Ytrehus
Keyword(s):  
Shear Rate ◽  
Yield Point ◽  
Drilling Fluid ◽  
Sufficient Accuracy ◽  
Drilling Fluids ◽  
Thermodynamic Quantities ◽  
Shear Rates ◽  
Viscosity Measurements ◽  
Viscosity Models ◽  
Mineralogical Compositions

An evaluation is presented of the practical usage of the Herschel-Bulkley viscosity model for drilling fluids. If data from automatic viscosity measurements exist, the parameters should be selected from relevant shear rate ranges to be applicable. To be able to be used properly, viscosity measurements must be measured with a sufficient accuracy. It is shown that a manual reading of standard viscometers may yield insufficient accuracy. It is also shown that the use of yield point/plastic viscosity (YP/PV) as measured using API or ISO standards normally provide inaccurate viscosity parameters. The use of the Herschel-Bulkley model using dimensionless shear rates is more suitable than the traditional way of writing this model when the scope is to compare different drilling fluids. This approach makes it also easier to make correlations with thermodynamic quantities like pressure and temperature or chemical or mineralogical compositions of the drilling fluid.

Modelling of Drilling Fluid Thixotropy

2018 ◽  
Author(s):  
Eric Cayeux ◽  
Amare Leulseged
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Time Dependence ◽  
Rheological Properties ◽  
Drilling Fluid ◽  
Time Dependent ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Pump Flow Rate ◽  
Drilling Operations

Drilling fluids are visco-elastic materials, i.e. they behave as a viscous fluid when subject to a sufficient shear stress and like an elastic solid otherwise. Both their elastic and viscous properties are time-dependent, i.e. drilling fluids are thixotropic. Because of thixotropy, it takes a finite time before the effective viscosity of a drilling fluid attains an equilibrium when the fluid is subject to a change of shear rate. This effect is visible when one changes the applied shear rate in a rheometer, as the fluid will gradually adapt to the new shearing conditions. When the velocity of a drilling fluid changes, for instance due to a change in pump flow rate, movement of the drill string, or change of flow geometry, the fluid will exhibit a time-dependent response to the new shearing conditions, requiring a certain time to reach the new equilibrium condition. Unfortunately, the time-dependence of the rheological properties of drilling fluids are usually not measured during drilling operations and therefore it is difficult to estimate how thixotropy impacts pressure losses in drilling operations. For that reason, we have systematically measured the time-dependence of the rheological properties of several samples of water-based, oil-based and micronized drilling fluids with a scientific rheometer in order to capture how drilling fluids systems respond to variations of shear rates. Based on these measurements, we propose to investigate how one existing thixotropic model manages to predict the shear stress as a function of the shear rate while accounting for the shear history and gelling conditions. Then we propose a modified model that fits better, overall, with the measurements even though there are still noticeable discrepancies, especially when switching back to low shear rates.

Viscosity Function for Yield-Stress Liquids

2004 ◽  
Vol 14 (6) ◽  
pp. 296-302 ◽  
Author(s):  
Paulo R. Souza Mendes ◽  
Eduardo S. S. Dutra
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Power Law ◽  
Drilling Fluid ◽  
Oil Emulsion ◽  
Viscosity Function ◽  
Coating Formulation ◽  
Low Shear

Abstract A viscosity function for highly-shear-thinning or yield-stress liquids such as pastes and slurries is proposed. This function is continuous and presents a low shear-rate viscosity plateau, followed by a sharp viscosity drop at a threshold shear stress value (yield stress), and a subsequent power-law region. The equation was fitted to data for Carbopol aqueous solutions at two different concentrations, a drilling fluid, an water/oil emulsion, a commercial mayonnaise, and a paper coating formulation. The quality of the fittings was generally good.

scholarly journals RDR Application: An Accurate HTHP Rheological Modeling for The Sulphonated Water-Based Drilling Fluid

2017 ◽  
Vol 10 (1) ◽  
pp. 251-262 ◽  
Author(s):  
Lin Xu ◽  
Han Gao ◽  
Ming-biao Xu ◽  
Fu-chang You ◽  
Xiao-liang Wang
Keyword(s):  
Shear Rate ◽  
Rheological Model ◽  
Predictive Accuracy ◽  
Drilling Fluid ◽  
Rate Coefficients ◽  
Drilling Fluids ◽  
Shear Rates ◽  
Water Based ◽  
Rheological Modeling ◽  
Modeling Strategy

Introduction: An accurate HTHP rheological model of drilling fluids is critical for the safe and economic drilling operation. However, general HTHP rheological modeling methods appear to be very limited in the predictive accuracy. Materials and Method: In this work, a particular relative dial readings(RDR) modeling experiment was conducted on a weighted sulphonated water-based drilling fluid within a certain temperature and pressure range(30-150°C, 0.1-100MPa), in combination to dial reading data of six specific shear rates 3, 6, 100, 200, 300, and 600rpm, to develop a highly accurate HTHP rheological model. The RDR modeling procedure was investigated in details, including relative dial reading, Arrhenius relation, polynomial of pressure coefficients, and polynomial of shear rate coefficients. An equation relating RDR to temperature, pressure, and shear rate was determined. Results: The predictive deviation was calculated to be lower than 11.7%, and large errors occurred under the conditions of high pressure and low shear rates; all of which meet the requirement of in-field predictive accuracy. These results not only provide an accurate HTHP rheological equation for the weighted sulphonated water-based drilling fluid, but also propose an effective HTHP rheological modeling strategy for drilling fluids.

Adenosine Diphosphate-Induced Aggregation of Human Platelets in Flow Through Tubes: III. Shear and Extrinsic Fibrinogen-Dependent Effects

1994 ◽  
Vol 71 (01) ◽  
pp. 078-090 ◽  
Author(s):  
H L Goldsmith ◽  
M M Frojmovic ◽  
Susan Braovac ◽  
Fiona McIntosh ◽  
T Wong
Keyword(s):  
Shear Rate ◽  
Single Cells ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Size Analysis ◽  
Fibrinogen Concentration ◽  
Human Fibrinogen ◽  
Shear Rates ◽  
Rate Dependent ◽  
Induced Aggregation

SummaryThe effect of shear rate and fibrinogen concentration on adenosine diphosphate-induced aggregation of suspensions of washed human platelets in Poiseuille flow at 23°C was studied using a previously described double infusion technique and resistive particle counter size analysis (1). Using suspensions of multiple-centrifuged and -washed cells in Tyrodes-albumin [3 × 105 μl−1; (17)] with [fibrinogen] from 0 to 1.2μM, the, rate and extent of aggregation with 0.7 μM ADP in Tyrodes-albumin were measured over a range of mean transit times from 0.2 to 43 s, and at mean tube shear rates, Ḡ, = 41.9, 335 and 1,335 s−1. As measured by the decrease in singlet concentration, aggregation at 1.2 μM fibrinogen increased with increasing Ḡ up to 1,335 s1, in contrast to that previously reported in citratcd plasma, in which aggregation reached a maximum at Ḡ = 335 s−1. Without added fibrinogen, there was no aggregation at Ḡ = 41.9 s1; at Ḡ = 335 s1, there was significant aggregation but with an initial lag time, aggregation increasing further at Ḡ = 1,335 s−1. Without added fibrinogen, aggregation was abolished at all Ḡ upon incubation with the hexapeptide GRGDSP, but was almost unaffected by addition of an F(ab’)2 fragment of an antibody to human fibrinogen. Aggregation in the absence of added fibrinogen was also observed at 37°C. The activation of the multiple-washed platelets was tested using flow cytometry with the fluorescently labelled monoclonal antibodies FITC-PAC1 and FITC-9F9. It was shown that 57% of single cells in unactivated PRT expressed maximal GPIIb-IIIa fibrinogen receptors (MoAb PAC1) and 54% expressed pre-bound fibrinogen (MoAb 9F9), with further increases on ADP activation. However, incubation with GRGDSP and the F(ab’)2 fragment did not inhibit the prebound fibrinogen. Moreover, relatively unactivated cells (8% expressing receptor, 14% prebound fibrinogen), prepared from acidified cPRP by single centrifugation with 50 nM of the stable prostacyclin derivative, ZK 36 374, and resuspension in Tyrodes-albumin at 5 × 104 μl−1, aggregated with 2 and 5 μM ADP at Ḡ = 335 and 1,335 s−1 in the absence of added fibrinogen. We therefore postulate that a protein such as von Willebrand factor, secreted during platelet isolation or in flow at sufficiently high shear rates, may yield the observed shear-rate dependent aggregation without fibrinogen.

Annular Frictional Pressure Losses During Drilling—Predicting the Effect of Drillstring Rotation

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Arild Saasen
Keyword(s):  
Rheological Properties ◽  
Pressure Loss ◽  
Drilling Fluid ◽  
Axial Flow ◽  
Drilling Fluids ◽  
Unstable Flow ◽  
Pressure Losses ◽  
Shear Dependent Viscosity ◽  
Water Based ◽  
Dependent Viscosity

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus which reduces the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that destabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In this paper, all the above mentioned phenomena and their consequences for annular pressure losses will be discussed in detail. North Sea field data is used as an example. It is not straightforward to build general annular pressure loss models. This argument is based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.

scholarly journals Synthesis and development of smart drilling fluids using nanoparticles to tailor their transport properties for enhanced drilling operations

2018 ◽  
Author(s):  
Ζήσης Βρύζας
Keyword(s):  
Transport Properties ◽  
Yield Stress ◽  
Drilling Fluid ◽  
Fluid Loss ◽  
Drilling Fluids ◽  
Natural Fractures ◽  
Custom Made ◽  
Drilling Operations ◽  
Induced Fractures

Η γεώτρηση αποτελεί την πλέον δαπανηρή εργασία σε μια καμπάνια εξεύρεσης και παραγωγής υδρογονανθράκων. Πέραν αυτού συνιστά και την μοναδική διεργασία που δίνει τη δυνατότητα ακριβούς προσδιορισμού των αποθεμάτων στο υπέδαφος. Ο πολφός (γεωτρητικά ρευστά) είναι το ‘αίμα’ της γεώτρησης: παρέχει πίεση, μεταφορά τριμμάτων/θραυσμάτων από τον πυθμένα του φρέατος, ψύξη και λίπανση κοπτικού και στήλης, καθώς επίσης διατηρεί τα θραύσματα εν αιωρήσει όταν υπάρχει διακοπή της κυκλοφορίας. Ως ρευστό γεώτρησης (drilling fluid) χρησιμοποιείται συνήθως ένα αιώρημα πηλού και άλλων υλικών σε νερό. Τα ρευστά διάτρησης με βάση το νερό αποτελούνται από α) νερό, το οποίο αποτελεί την συνεχή φάση και παρέχει το αρχικό ιξώδες (φρέσκο ή θαλασσινό), β) ενεργά στερεά για την ενίσχυση του ιξώδους και του σημείου διαρροής (μπεντονίτης, που συνιστάται στην περίπτωση του φρέσκου νερού και ατταπουλγίτης, αμίαντος ή σιπιόλιθος, που συνιστώνται στην περίπτωση του θαλασσινού νερού), και γ) αδρανή στερεά για την επίτευξη της απαιτούμενης πυκνότητας (βαρύτης, θειούχος μόλυβδος, σιδηρομεταλλεύματα ή χαλαζιακά υλικά).Τα γεωτρητικά ρευστά αποτελούν το 10-20% του συνολικού κόστους κατά την διάρκεια μιας γεώτρησης. Ποσοστό πολύ υψηλό όταν μιλάμε για επενδύσεις εκκατομυρίων δολλαρίων. Λόγω των ολοένα πιο βαθιών αλλά και περίπλοκων γεωλογικών σχηματισμών υπάρχει τεράστια ανάγκη από την πετρελαική βιομηχανία για καινούργια και περισσότερο αποδοτικά γεωτρητικά ρευστά τα οποία θα μπορούν να ανταπεξέλθουν στα ολοένα και πιο απαιτητικά περβάλλοντα θερμοκρασίας και πίεσης. Τα σημαντικότερα ζητήματα τα οποία καλούνται να ανταποκριθούν τα ρευστά είναι οι ολοένα αυξανόμενες συνθήκες πίεσης και θερμοκρασίας στο υπέδαφος που είναι απόροια της αναζήτησης υδρογονανθράκων σε πλέον δύσβατες περιοχές με μεγαλύτερα βάθη που αυξάνουν τους κινδύνους και το κόστος για μια γεώτρηση. Η απώλεια ρευστού κυκλοφορίας (fluid loss) είναι ένα από τα σημαντικότερα και πλέον δαπανηρά προβλήματα κατά την διαδικασία μιας γεώτρησης. Ως απώλεια ρευστού κυκλοφορίας ορίζεται η συνολική ή μερική απώλεια των ρευστών της γεώτρησης σε εξαιρετικά διαπερατές ζώνες (porous sands), σε σπηλαιώδεις σχηματισμούς (cavernous zones), σε φυσικές ρηγματώσεις (natural fractures) και σε ρηγματώσεις προκαλούμενες κατά τη διάτρηση (induced fractures). Τα τελευταία χρόνια έχουν γίνει αρκετές προσπάθειες για την βελτίωση των γεωτρητικών ρευστών με την χρήση νανοσωματιδίων, τα οποία έχουν τη δυνατότητα να βελτιώσουν τις ιδιότητες των γεωτρητικών ρευστών όταν προστίθενται ακόμα και σε χαμηλές συγκεντρώσεις (<1 wt%). Οι μοναδικές τους ιδιότητες σχετίζονται με το μικρό τους μέγεθος και επομένως τον εξαιρετικά μεγάλο λόγο επιφάνειας προς όγκο.Σε αυτή την εργασία, εξετάστηκαν διάφορα εμπορικά νανοσωματίδια (Fe2O3, Fe3O4, SiO2) καθώς επίσης συντέθηκαν, με την μέθοδο της συγκαταβύθισης, νανοσωματιδία μαγνητίτη (custom-made Fe3O4), με και χωρίς επικάλυψη κιτρικού οξέος, τα οποία ερευνήθηκαν ως προς την ικανότητα τους να βελτιώσουν τις ρεολογικές ιδιότητες και την απώλεια ρευστών σε αιωρήματα μπετονίτη. Προκειμένου να χαρακτηρισθούν φυσικοχημικά τα αιωρήματα υπέστησαν ξήρανση με κοκκοποίηση σε θερμοκρασία υγρού Ν2 και κρυοξήρανση. Η μορφολογία, η κρυσταλλική δομή και οι επιφανειακές ομάδες των ξηρών κόνεων εξετάσθηκαν με ηλεκτρονική μικροσκοπία HR-TΕM, περίθλαση ακτίνων Χ (XRD), φυσική ρόφηση Ν2 και φασματοσκοπία FTIR. Οι αλληλεπιδράσεις των σωματιδίων μπετονίτη με τα νανοσωματίδια και οι διάφορες δομές που δημιουργούνται και πως τελικά αυτές επηρεάζουν τις ρεολογικές ιδιότητες των αιωρημάτων εξετάστηκαν με το HR-TEM στους 25°C και 60°C. Με βάση τις εικόνες από το HR-TEM, ένα μοντέλο αλληλεπιδράσεων μεταξύ των διαφορετικών τύπων νανοσωματιδίων και σωματιδίων μπετονίτη δημιουργήθηκε για πρώτη φορά για τέτοια αιωρήματα. Οι ρεολογικές ιδιότητες των παραγόμενων δειγμάτων εξετάστηκαν και σε συνθήκες ατμοσφαιρικής πίεσης (μέχρι 70°C) με την χρήση περιστροφικού ιξωδόμετρου (Grace M3600-Couette type geometry) αλλά και σε συνθήκες υψηλής πίεσης και θερμοκρασίας (69 bar-121°C) (Chandler 7600 HPHT viscometer). Το μοντέλο Herschel-Bulkley χρησιμοποιήθηκε για να περιγράψει τη μεταβολή του ιξώδους με τη μεταβολή των ρεολογικών παραμέτρων δείχνοντας εξαιρετική εφαρμογή για τις διαφορετικές πειραματικές μετρήσεις με συντελεστές συσχέτισης (R2) >0.99 σε όλες τις περιπτώσεις. Οι ρεολογικές μετρήσεις έδειξαν ότι η προσθήκη των νανοσωματιδίων βελτιώνει σημαντικά τις ρεολογικές ιδιότητες των αιωρημάτων μπετονίτη στις διάφορες συνθήκες πίεσης και θερμοκρασίας. Οι απώλειες ρευστών (fluid loss) εξετάστηκαν με φιλτροπρέσες υψηλής πίεσης και θερμοκρασίας (20.7 bar και 121°C) οι οποίες υπολογίζουν τον ρυθμό διήθησης του πολφού μέσω του χρησιμοποιούμενου φίλτρου (κεραμικός δίσκος). Η μεγαλύτερη μείωση στην απώλεια ρευστών επιτεύχθηκε για το δείγμα που περιείχε 0.5 wt% custom-made Fe3O4 με μείωση -40% σε σχέση με το αρχικό δείγμα μπετονίτη που δείχνει την τεράστια ικανότητα των νανοσωματιδίων να βελτιώσουν σημαντικά τις απώλειες ρευστών ακόμα και σε τόσο μικρές συγκεντρώσεις. Τέλος, εξετάστηκε η ικανότητα των παραγόμενων ρευστών να αλλάζουν τις ρεολογικές τους ιδιότητες υπό την επίδραση διάφορων μαγνητικών πεδίων (μέχρι 0.7 Tesla). Τα αποτελέσματα έδειξαν ότι τα καινούργια γεωτρητικά ρευστά έχουν την ικανότητα να αυξάνουν την τάση διολίσθησης (yield stress) έως και 300% σε σχέση με αυτή που μετρήθηκε χωρίς την εφαρμογή μαγνητικού πεδίου. Αυτό είναι κάτι πολύ σημαντικό που επιτρέπει την χρήση έξυπνων ρευστών (smart drilling fluids) τα οποία μπορούν να εξοικονομήσουν και χρόνο αλλά και κόστη κατά την διάρκεια μιας γεώτρησης.Τα νανοσωματίδια δείχνουν πολλές ελπιδοφόρες δυνατότητες σε εφαρμογές γεωτρήσεων αφού έχουν τη δυνατότητα να βελτιώσουν ή και να λύσουν το πρόβλημα της απώλειας ρευστών, όταν προστίθενται ακόμα και σε χαμηλές συγκεντρώσεις (>0.5 wt%), ενώ ταυτόχρονα βελτιστοποιούν τις ρεολογικές ιδιότητες των γεωτρητικών ρευστών. Η χρήση τους για την ανάπτυξη βελτιωμένων γεωτρητικών ρευστών υπόσχεται να αλλάξει την βιομηχανία των γεωτρήσεων και να την βοηθήσει να εξορυχθούν πολύπλοκοι γεωλογικοί σχηματισμοί πιο αποδοτικά αλλά και οικονομικά.

Application of R/S Rheometer in Low Temperature Drilling Fluid Rheology Determination

2012 ◽  
Vol 490-495 ◽  
pp. 3114-3118
Author(s):  
Xiao Ling Jiang ◽  
Zong Ming Lei ◽  
Kai Wei
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Low Temperature ◽  
High Speed ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Rheological Parameter ◽  
Fluid Temperature ◽  
Fluid Rheology ◽  
Rotary Viscometer

With six-speed rotary viscometer measuring the rheology of drilling fluid at low temperature, during the high-speed process, the drilling fluid temperature is not constant at low temperature, which leads to the inaccuracy in rheological measurement. When R/S rheometer is used cooperating with constant low-temperature box , the temperature remains stable during the process of determining the drilling fluid rheology under low temperature. The R/S rheometer and the six-speed rotational viscometer are both coaxial rotational viscometers, but they work in different ways and the two cylindrical clearance between them are different.How to make two viscometer determination result can maintain consistent?The experimental results show that, The use of R/S rheometer, with the shear rate for 900s-1 shear stress values instead of six speed rotary viscometer shear rate for 1022s-1 shear stress values.Then use two-point formula to calculate rheological parameters.The R/S rheometer rheological parameter variation with temperature has a good linear relationship,Can better reflect the rheological properties of drilling fluids with low temperature changerule

Shear rate dependent margination of sphere-like, oblate-like and prolate-like micro-particles within blood flow

Soft Matter ◽  
2018 ◽  
Vol 14 (36) ◽  
pp. 7401-7419 ◽  
Author(s):  
Huilin Ye ◽  
Zhiqiang Shen ◽  
Ying Li
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Shape Effect ◽  
Shear Rates ◽  
Micro Particles ◽  
Rate Dependent ◽  
Wall Shear

The shape effect of micro-particles is examined by comparing the margination behaviors of sphere-like, oblate-like and prolate-like micro-particles under different wall shear rates in blood flow.

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