A New Approach to Evaluate Temperature Effects on Rheological Behavior of Formate-Based Fluids

2002 ◽  
Vol 124 (3) ◽  
pp. 141-145 ◽  
Author(s):  
Rosana F. T. Lomba ◽  
Carlos H. M. de Sa´ ◽  
Edimir M. Branda˜o
Keyword(s):  
Rheological Behavior ◽  
Good Alternative ◽  
Extensive Study ◽  
Organic Salt ◽  
Drilling Fluids ◽  
Shear Stresses ◽  
New Approach ◽  
Completion Fluids ◽  
Best Fit ◽  
Special Case

Organic salt brines represent a good alternative to drill through deep productive zones. The literature presents these salts as thermal stabilizers of polymers used in the formulation of drill-in fluids. An extensive study was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature and density. An analytical expression was developed to correlate shear stresses with temperature for general drilling fluids and a special case of this expression results in a greatly simplified expression that is valid for a number of drilling and completion fluids produced using different alkali-metal salts of formic acid. The advantage of this new approach is the lack of dependence between the proposed correlation and the choice of a rheological model. Unlike many expressions presented in the literature, the expression proposed and methodology that follows allows the choice of a best-fit model to predict the fluid’s rheological behavior as a function of temperature. Experimental results show that formates do improve the thermal stability of polymers. The proposed correlations will soon be incorporated in a wellbore cleaning numerical simulator to compensate for thermal effects.

scholarly journals Biopolymer Drill-in Fluid Performance for Different Rheological Models using Statistical Characterisation

2019 ◽  
Vol 19 (1) ◽  
pp. 86-92
Author(s):  
M. Owusu ◽  
H. Osei
Keyword(s):  
Rheological Model ◽  
Rheological Behaviour ◽  
Primary Objective ◽  
Least Square ◽  
Model Parameters ◽  
Drilling Fluids ◽  
Cleaning Efficiency ◽  
Rheological Models ◽  
Least Square Regression ◽  
Best Fit

Appropriate selection of rheological models is important for hydraulic calculations of pressure loss prediction and hole cleaning efficiency of drilling fluids. Power law, Bingham-Plastic and Herschel-Bulkley models are the conventional fluid models used in the oilfield. However, there are other models that have been proposed in literature which are under/or not utilized in the petroleum industry. The primary objective of this paper is to recommend a rheological model that best-fits the rheological behaviour of xanthan gum-based biopolymer drill-in fluids for hydraulic evaluations. Ten rheological models were evaluated in this study. These rheological models have been posed deterministically and due to the unrealistic nature have been replaced by statistical models, by adding an error (disturbance) term and making suitable assumptions about them. Rheological model parameters were estimated by least-square regression method. Models like Sisko and modified Sisko which are not conventional models in oil industry gave a good fit. Modified Sisko model which is a four parameter rheological model was selected as the best-fit model since it produced the least residual mean square of 0.61 Ibf2/100ft4. There is 95% certainty that the true best-fit curve lies within the confidence band of this function of interest. Keywords: Biopolymer; Least-Square Regression; Residual Mean Squares; Rheologram

Nonlinear Theory for Composite Laminated Shells With Interfacial Damage

1998 ◽  
Vol 65 (3) ◽  
pp. 711-718 ◽  
Author(s):  
Zhen-qiang Cheng ◽  
S. Kitipornchai
Keyword(s):  
Nonlinear Theory ◽  
Virtual Work ◽  
Shear Stresses ◽  
Interfacial Damage ◽  
Laminated Shells ◽  
Lines Of Curvature ◽  
Perfect Bonding ◽  
Transverse Shear Stresses ◽  
Bounding Surfaces ◽  
Special Case

Interfacial damage is incorporated in the proposed nonlinear theory. for composite laminated shells. A spring-layer model is employed to characterize damaged interfaces spanning from perfect bonding to different degrees of imperfect bonding in shear. By enforcing compatibility conditions for transverse shear stresses both at interfaces and on two bounding surfaces of a laminated shell, only five unknowns are needed for modeling its behavior. The principle of virtual work is used to derive the governing equations, which are of 14th order in lines of curvature coordinates, variationally self-consistent with seven prescribed boundary conditions. This theory includes the conventional higher-order zigzag model for a perfectly bonded shell as a special case. Numerical results provide a physical understanding of the effect of interracial damage on bending and buckling responses of composite laminated shells.

Inhibiting Calcium Chloride Heavy Brines to be Used as Drilling Fluids: Hurdles Encountered in Treatment, Application, Corrosion Mitigation, Solubility, and Foaming Tendencies for Drilling Sites in Canada

2021 ◽  
Author(s):  
Thenuka M. Ariyaratna ◽  
Nihal U. Obeyesekere ◽  
Tharindu S. Jayaneththi ◽  
Jonathan J. Wylde
Keyword(s):  
Corrosion Inhibitor ◽  
Corrosion Inhibitors ◽  
Drilling Fluid ◽  
Solvent System ◽  
Test Fluid ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Drill Cuttings ◽  
Well Completion ◽  
Completion Fluids

Abstract A need for more economic drilling fluids has been addressed by repurposing heavy brines typically used as completion fluids. Heavy brine corrosion inhibitors have been designed for stagnant systems. Drilling fluids are subjected to both heavy agitation and aeration through recirculation systems and atmospheric exposure during the various stages of the drilling process. This paper documents the development of heavy brine corrosion inhibitors to meet these additional drilling fluid requirements. Multiple system scenarios were presented requiring a methodical evaluation of corrosion inhibitor specifications while still maintaining performance. Due to the high density of heavy brine, traditional methods of controlling foaming were not feasible or effective. Additional product characteristics had to be modified to allow for the open mud pits where employees would be working, higher temperatures, contamination from drill cuttings, and product efficacy reduction due to absorption from solids. The product should not have any odor, should have a high flash point, and mitigate corrosion in the presence of drill cuttings, oxygen, and sour gases. Significant laboratory development and testing were done in order to develop corrosion inhibitors for use in heavy brines based on system conditions associated with completion fluids. The application of heavy brine as a drilling fluid posed new challenges involving foam control, solubility, product stability, odor control, and efficacy when mixed with drill cuttings. The key to heavy brine corrosion inhibitor efficacy is solubility in a supersaturated system. The solvent packages developed to be utilized in such environments were highly sensitive and optimized for stagnant and sealed systems. Laboratory testing was conducted utilizing rotating cylinder electrode tests with drill cuttings added to the test fluid. Product components that were found to have strong odors or low flash points were removed or replaced. Extensive foaming evaluations of multiple components helped identify problematic chemistries. Standard defoamers failed to control foaming but the combination of a unique solvent system helped to minimize foaming. The evaluations were able to minimize foaming and yield a low odor product that was suitable for open mud pits and high temperatures without compromising product efficacy. The methodology developed to transition heavy brine corrosion inhibitors from well completion applications to drilling fluid applications proved to be more complex than initially considered. This paper documents the philosophy of this transitioning and the hurdles that were overcome to ensure the final product met the unique system guidelines. The novel use of heavy brines as drilling fluids has created a need for novel chemistries to inhibit corrosion in a new application.

Comparison of organo-sepiolite modified by different surfactants and their rheological behavior in oil-based drilling fluids

2018 ◽  
Vol 159 ◽  
pp. 94-101 ◽  
Author(s):  
Jianle Weng ◽  
Zhijin Gong ◽  
Libing Liao ◽  
Guocheng Lv ◽  
Jianjie Tan
Keyword(s):  
Rheological Behavior ◽  
Drilling Fluids

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 Effect of a modified nano clay and nano graphene on rheology, stability of water-in-oil emulsion, and filtration control ability of oil-based drilling fluids: a comparative experimental approach

2020 ◽  
Vol 75 ◽  
pp. 40
Author(s):  
Vahid Nooripoor ◽  
Abdolnabi Hashemi
Keyword(s):  
Base Fluid ◽  
Emulsion Stability ◽  
Nano Particles ◽  
Model Parameters ◽  
Drilling Fluids ◽  
Shear Stresses ◽  
Oil Emulsion ◽  
Nano Clay ◽  
Nano Graphene ◽  
Water In Oil Emulsion

During the past decade, researchers have used different Nano-Particles (NPs) due to their unique characteristics for improving formulation of Oil-Based Drilling Fluids (OBDFs). This study is the first research that investigates the effect of a Modified Nano Clay (MNC), namely CLOISITE 5 and non-functionalized Nano Graphene (NG) on rheology, electrical/emulsion stability, and filtration control ability, as the main properties of OBDFs. Initially, five concentrations of both NPs (0.25, 0.5, 1, 1.5, and 2 wt%) were added separately into an NP-free OBDF (the base fluid). Then, rheological properties and electrical stability of all prepared fluids were measured at three 90, 140, and 180 °F temperatures. Moreover, filtration test was carried out under 500 psi (3447 kPa) differential pressure and exposed to 300 °F temperature for all fluids. Since experimentally measured shear stresses followed well both Herschel Bulkley (shear-thinning) and Bingham Plastic models, effects of temperature and the NPs concentration on both model parameters are investigated more deeply in the paper. Activation energies calculated from Arrhenius model showed that MNC is more effective than NG on reducing the dependency of apparent and plastic viscosities of the base fluid on temperature. MNC, due to its amphiphilic structure, significantly stabilizes water-in-oil emulsion at all temperatures and concentrations, but NG with high electrical conductivity reduces the emulsion stability. The nanofluids containing 0.5 wt% MNC and 0.25 wt% NG which have respectively 32.6% and 43.5% fewer filtrate volumes than the base fluid, were considered as the optimal nanofluids from controlling filtration into formation aspect. Finally, MNC is applicable to enhance the formulation of the OBDF through supporting its commercial viscosifier, emulsifiers, and fluid loss control agent, but the negative effect of NG on emulsion stability limits its application.

scholarly journals Parabolic Sandwiches for Functions on a Compact Interval and an Application to Projectile Motion

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Robert Kantrowitz ◽  
Michael M. Neumann
Keyword(s):  
Present Article ◽  
Decisive Role ◽  
Valid Argument ◽  
Quadratic Polynomials ◽  
New Approach ◽  
Projectile Motion ◽  
Full Result ◽  
Air Resistance ◽  
Special Case ◽  
Natural Way

About a century ago, the French artillery commandant Charbonnier envisioned an intriguing result on the trajectory of a projectile that is moving under the forces of gravity and air resistance. In 2000, Groetsch discovered a significant gap in Charbonnier’s work and provided a valid argument for a certain special case. The goal of the present article is to establish a rigorous new approach to the full result. For this, we develop a theory of those functions which can be sandwiched, in a natural way, by a pair of quadratic polynomials. It turns out that the convexity or concavity of the derivative plays a decisive role in this context.

From direct-space discrepancy functions to crystallographic least squares

2015 ◽  
Vol 71 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Carmelo Giacovazzo
Keyword(s):  
Least Squares ◽  
Crystal Structure Analysis ◽  
Scaling Factor ◽  
Mathematical Approach ◽  
New Approach ◽  
Density Maps ◽  
Scattering Contribution ◽  
Special Case ◽  
Degree Of Similarity

Crystallographic least squares are a fundamental tool for crystal structure analysis. In this paper their properties are derived from functions estimating the degree of similarity between two electron-density maps. The new approach leads also to modifications of the standard least-squares procedures, potentially able to improve their efficiency. The role of the scaling factor between observed and model amplitudes is analysed: the concept ofunlocated modelis discussed and its scattering contribution is combined with that arising from thelocated model. Also, the possible use of an ancillary parameter, to be associated with the classical weight related to the variance of the observed amplitudes, is studied. The crystallographic discrepancy factors, basic tools often combined with least-squares procedures in phasing approaches, are analysed. The mathematical approach here described includes, as a special case, the so-called vector refinement, used when accurate estimates of the target phases are available.

scholarly journals A NEW APPROACH TO THE PARAMETRIZATION OF THE CABIBBO–KOBAYASHI–MASKAWA MATRIX

2001 ◽  
Vol 16 (09) ◽  
pp. 1645-1652 ◽  
Author(s):  
V. GUPTA
Keyword(s):  
Cp Violation ◽  
Linear Combination ◽  
Quark Mass ◽  
New Approach ◽  
Ckm Matrix ◽  
Unit Matrix ◽  
Mass Matrices ◽  
The Matrix ◽  
Special Case

The CKM-matrix V is written as a linear combination of the unit matrix I and a matrix U which causes intergenerational-mixing. It is shown that such a V results from a class of quark-mass matrices. The matrix U has to be Hermitian and unitary and therefore can depend at most on four real parameters. The available data on the CKM-matrix including CP-violation can be reproduced by [Formula: see text]. This is also true for the special case when U depends on only 2 real parameters. Also, for such a V the invariant phase Φ≡ϕ12+ϕ23-ϕ13, satisfies a criterion suggested for "maximal" CP-violation.

Starting solutions for the motion of second grade fluids due to oscillating shear stresses

2015 ◽  
Vol 4 (2) ◽  
Author(s):  
Muhammad Jamil
Keyword(s):  
Analytic Solutions ◽  
Second Grade ◽  
Shear Stresses ◽  
Exact Analytic Solutions ◽  
Transient Solutions ◽  
Grade Fluid ◽  
Starting Solutions ◽  
Second Grade Fluids ◽  
Graphical Illustration ◽  
Special Case

AbstractExact analytic solutions for the motion of second grade fluid between two infinite coaxial cylinders are established. The motion is produced by the inner cylinder that at time t = 0+ applies torsional and longitudinal oscillating shear stresses to the fluid. The exact analytic solutions, obtained with the help of Laplace and finite Hankel transforms, and presented as a sum of the steady-state and transient solutions, satisfy both the governing equations and all associate initial and boundary conditions. In the special case when a1 to 0 they reduce to those for a Newtonian fluid. Finally, the effect of various parameters of interest on transient parts of velocity components, velocity profiles as well as comparison between second grade and Newtonian fluids is discussed through graphical illustration.

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