New Fracturing Fluid Viscosity Model to Cure Power Law Mistakes

Abstract Proppant flowback is a significant issue in the field of fractured well production. In order to investigate the influencing relationships among the parameters affecting proppant flowback, the weight of proppant flowback within different conditions was tested by applying a fracture simulation experiment device. During the experiments, the flowback velocity of the fracturing fluid, the viscosity of the fracturing fluid, the proppant particle size, and the effective closure pressure were studied. The experimental results indicated that the flowback velocity of the fracturing fluid is critical for proppant flowback. The weight of the flowback proppant increases as the fracturing fluid flowback velocity increases. Proppant flowback mainly occurs in the early stage of fracturing fluid flowback; more than 75% of the flowback volume of the proppant was carried by 33.33% of the fracturing fluid flowback volume. The weight of the flowback proppant decreases as the flowback fracturing fluid viscosity decreases. Using a larger particle size proppant or upon increasing effective closure pressure also can decrease the weight of the flowback proppant.

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Influence of inorganic ions in recycled produced water on gel-based hydraulic fracturing fluid viscosity

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2015.12.021 ◽

2016 ◽

Vol 139 ◽

pp. 104-111 ◽

Cited By ~ 11

Author(s):

N. Esmaeilirad ◽

S. White ◽

C. Terry ◽

A. Prior ◽

K. Carlson

Keyword(s):

Hydraulic Fracturing ◽

Produced Water ◽

Inorganic Ions ◽

Fluid Viscosity ◽

Fracturing Fluid ◽

Hydraulic Fracturing Fluid

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Non-Newtonian Natural Convection Along a Vertical Heated Wavy Surface Using a Modified Power-Law Viscosity Model

Journal of Heat Transfer ◽

10.1115/1.2977556 ◽

2008 ◽

Vol 131 (1) ◽

Cited By ~ 9

Author(s):

M. M. Molla ◽

L. S. Yao

Keyword(s):

Boundary Layer ◽

Natural Convection ◽

Shear Rate ◽

Power Law ◽

Leading Edge ◽

Numerical Results ◽

Wavy Surface ◽

Viscosity Model ◽

Length Scale ◽

Modified Power Law

Natural convection of non-Newtonian fluids along a vertical wavy surface with uniform surface temperature has been investigated using a modified power-law viscosity model. An important parameter of the problem is the ratio of the length scale introduced by the power-law and the wavelength of the wavy surface. In this model there are no physically unrealistic limits in the boundary-layer formulation for power-law, non-Newtonian fluids. The governing equations are transformed into parabolic coordinates and the singularity of the leading edge removed; hence, the boundary-layer equations can be solved straightforwardly by marching downstream from the leading edge. Numerical results are presented for the case of shear-thinning as well as shear-thickening fluid in terms of the viscosity, velocity, and temperature distribution, and for important physical properties, namely, the wall shear stress and heat transfer rates in terms of the local skin-friction coefficient and the local Nusselt number, respectively. Also results are presented for the variation in surface amplitude and the ratio of length scale to surface wavelength. The numerical results demonstrate that a Newtonian-like solution for natural convection exists near the leading edge where the shear-rate is not large enough to trigger non-Newtonian effects. After the shear-rate increases beyond a threshold value, non-Newtonian effects start to develop.

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Flow Induced By A Rotating Microchannel-A Numerical Study

10.21203/rs.3.rs-587939/v1 ◽

2021 ◽

Author(s):

Kashif Ali ◽

Shahzad Ahmad ◽

Anique Ahmad ◽

Faisal Ali

Keyword(s):

Power Law ◽

Hartmann Number ◽

Stokes Equations ◽

Numerical Study ◽

Wall Slip ◽

Future Generation ◽

Fluid Viscosity ◽

Power Law Fluid ◽

Fluid Behavior ◽

Behavior Index

Abstract In this paper, a mathematical foundation has been developed for the primary understanding of complex interaction of the wall slip with the Coriolis and Lorentz forces acting orthogonally on the Electromagnetohydrodynamic (EMHD) flow of a power-law fluid in a microchannel. Modified Navier Stokes equations are solved numerically by incorporating the fully implicit computational scheme with suitable initial and boundary conditions, which generates numerical results in excellent comparison with the literature for a certain limiting case. An extensive effort has been made to understand how the Hartmann number, fluid behavior index, rotating Reynolds number, and slip parameter affects the flow. Results show the velocity of the power-law fluid depends strongly on flow parameters. Critical Hartmann number can be obtained for the power-law fluid in presence of uniform electric and magnetic fields. As a promising phenomenon, existence of a cross over point (which depends upon the fluid behavior index) for the centerline flow velocity, has also been predicted. Reduction in the shear stress and fluid viscosity can be controlled effectively by incorporating a slippery film of lubricant on the periphery of the microchannel. This work is useful to meet the upcoming challenges of future generation, like improvement in bio-magnetic-sensor technologies as well as electrical and mechanical mechanisms.

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Viscosity Models for Drilling Fluids: Viscosity Parameters and Their Use

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology ◽

10.1115/omae2019-96595 ◽

2019 ◽

Author(s):

Arild Saasen ◽

Jan David Ytrehus

Keyword(s):

Shear Rate ◽

Yield Stress ◽

Yield Point ◽

Power Law ◽

Physical Parameters ◽

Fluid Viscosity ◽

Reasonable Accuracy ◽

Bingham Model ◽

Viscosity Models ◽

Power Law Exponent

Abstract The most common viscosity models used in the drilling industry are the Bingham, the Power-Law and the Herschel-Bulkley models. The scope of the present paper is to outline how to select the individual models, and how the models need to be re-formulated to be able to have parameters with a physical meaning. In principle, the Bingham model itself have physical parameters being the yield point and the plastic viscosity. However, the Bingham model very often only very poorly describe the viscosity in complex fluids. This yield stress can be described within a reasonable accuracy by application of the low-shear yield point. A similar problem exists with the Power-Law model resulting from the model’s absence of a yield stress. The compromise model is the Herschel-Bulkley model which contains a yield stress and a power-law term. This model describes the drilling fluid viscosity with reasonable accuracy and includes both the Bingham and Power-Law models as limit formulations. It is not possible to select fluids based on the Herschel-Bulkley traditional parameters alone. The reason is that the Herschel-Bulkley power-law term’s viscosity parameter has a unit dependent on its power-law exponent. In the present approach the fluid is described using a yield stress, a surplus stress at a characteristic shear rate of the fluid flow and finally a power-law exponent making the fluid applicable in the practical shear rate ranges. The surplus stress is no-longer dependent on other parameters. Hence, we have re-arranged the viscosity model to have independent measurable quantities.

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A Novel Hydraulic Fracturing Method Based on the Coupled CFD-DEM Numerical Simulation Study

Applied Sciences ◽

10.3390/app10093027 ◽

2020 ◽

Vol 10 (9) ◽

pp. 3027

Author(s):

Cong Lu ◽

Li Ma ◽

Zhili Li ◽

Fenglan Huang ◽

Chuhao Huang ◽

...

Keyword(s):

Numerical Simulation ◽

Hydraulic Fracturing ◽

Variable Viscosity ◽

Oil Reservoirs ◽

Fluid Viscosity ◽

Low Density ◽

Fracturing Fluid ◽

Proppant Transport ◽

Fracturing Fluids ◽

Transport Experiment

For the development of tight oil reservoirs, hydraulic fracturing employing variable fluid viscosity and proppant density is essential for addressing the problems of uneven placement of proppants in fractures and low propping efficiency. However, the influence mechanisms of fracturing fluid viscosity and proppant density on proppant transport in fractures remain unclear. Based on computational fluid dynamics (CFD) and the discrete element method (DEM), a proppant transport model with fluid–particle two-phase coupling is established in this study. In addition, a novel large-scale visual fracture simulation device was developed to realize the online visual monitoring of proppant transport, and a proppant transport experiment under the condition of variable viscosity fracturing fluid and proppant density was conducted. By comparing the experimental results and the numerical simulation results, the accuracy of the proppant transport numerical model was verified. Subsequently, through a proppant transport numerical simulation, the effects of fracturing fluid viscosity and proppant density on proppant transport were analyzed. The results show that as the viscosity of the fracturing fluid increases, the length of the “no proppant zone” at the front end of the fracture increases, and proppant particles can be transported further. When alternately injecting fracturing fluids of different viscosities, the viscosity ratio of the fracturing fluids should be adjusted between 2 and 5 to form optimal proppant placement. During the process of variable proppant density fracturing, when high-density proppant was pumped after low-density proppant, proppants of different densities laid fractures evenly and vertically. Conversely, when low-density proppant was pumped after high-density proppant, the low-density proppant could be transported farther into the fracture to form a longer sandbank. Based on the abovementioned observations, a novel hydraulic fracturing method is proposed to optimize the placement of proppants in fractures by adjusting the fracturing fluid viscosity and proppant density. This method has been successfully applied to more than 10 oil wells of the Bohai Bay Basin in Eastern China, and the average daily oil production per well increased by 7.4 t, significantly improving the functioning of fracturing. The proppant settlement and transport laws of proppant in fractures during variable viscosity and density fracturing can be efficiently revealed through a visualized proppant transport experiment and numerical simulation study. The novel fracturing method proposed in this study can significantly improve the hydraulic fracturing effect in tight oil reservoirs.

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Improving the Thermal Stability of Hydrophobic Associative Polymer Aqueous Solution Using a “Triple-Protection” Strategy

Polymers ◽

10.3390/polym11060949 ◽

2019 ◽

Vol 11 (6) ◽

pp. 949 ◽

Cited By ~ 2

Author(s):

Bo Yang ◽

Jincheng Mao ◽

Jinzhou Zhao ◽

Yang Shao ◽

Yang Zhang ◽

...

Keyword(s):

High Temperature ◽

High Temperatures ◽

Elevated Temperatures ◽

Polymer Network ◽

Crosslinking Agent ◽

Water Soluble ◽

Fluid Viscosity ◽

Fracturing Fluid ◽

Temperature Resistance ◽

Protection Strategy

Because of their high viscoelasticity, Hydrophobic Associative Water-Soluble Polymers (HAWSPs) have been widely used in many industrial fields, especially in oilfield flooding and fracturing. However, one major problem which limits the wide applications of HAWSPs is their weak resistance to high temperatures. Once the temperature increases over 100 °C, the viscosity of the fracturing fluid decreases rapidly, because high temperatures reduce fluid viscosity by oxidizing the polyacrylamide chains and weakening the association of hydrophobic groups. To improve the high temperature resistance of one HAWSP, a triple-protection strategy was developed. First, rigid N-vinyl-2-pyrrolidone moiety was introduced into the polymer chains. Second, an environmentally-friendly deoxidizer, carbohydrazide, was selected to prevent polymer oxidization by scavenging dissolved oxygen. Results showed that both the rigid groups and the deoxidizer improved the temperature resistance of the polymer and helped it maintain high viscosity under high temperature and shear rate. Using these two protection strategies, the resistant temperature of the polymer could reach 160 °C. However, the polymer network still got severely damaged at further elevated temperatures. Therefore, as the third protection strategy, the pre-added high temperature responsive crosslinking agent was applied to form new networks at elevated temperatures. The results have shown that the optimized polymer solution as a kind of fracturing fluid showed good temperature resistance up to 200 °C.

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Falling Needle Rheometry for General Viscoelastic Fluids

Journal of Fluids Engineering ◽

10.1115/1.2910322 ◽

1994 ◽

Vol 116 (3) ◽

pp. 619-624 ◽

Cited By ~ 3

Author(s):

R. Zheng ◽

N. Phan-Thien ◽

V. Ilic

Keyword(s):

Aspect Ratio ◽

Power Law ◽

Unit Length ◽

Cylindrical Tube ◽

Terminal Velocity ◽

Fluid Viscosity ◽

General Technique ◽

Drag Forces ◽

Numerical Studies ◽

Power Law Index

This paper reports theoretical and numerical studies on a flow of a general viscoelastic fluid past a needle placed at the centerline of a cylindrical tube, supplemented by a comparative experimental study. It is shown that the drag per unit length on the needle, which is assumed to be infinitely long, depends on the fluid viscosity only, whatever the first and second normal stress differences may be. This general theory is then specified to obtain solutions for the power-law and the Phan-Thien-Tanner fluids. The power-law fluid results provide a general technique for obtaining flow curves of non-Newtonian fluids from the measured drag forces on falling needles. This is achieved by using KU/R as the effective shear rate, where U is the terminal velocity of the needle, R is the radius of the tube, and K is a function of the power-law index n and the system geometry a/R (where a is the radius of the needle). The effect of the aspect ratio of the needle on the drag force is investigated numerically using a boundary element method for the flow of Phan-Thien-Tanner fluid. Experimentally, a flow curve was obtained for a kerosene solution of PIB (3.39 percent by weight), using falling needles of aspect ratio greater than 40 in a circular cylinder. The result compared well with Carri-Med 50 CS rheometer data.

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