Effect of viscosity transition on oil flow in shale and tight rocks

2021 ◽  
pp. 1-25
Author(s):  
Jiangfeng Cui
Keyword(s):  
Crude Oil ◽  
Pore Radius ◽  
Flow Characteristics ◽  
Velocity Profiles ◽  
Analytical Models ◽  
Reduced Form ◽  
Microscale Flow ◽  
Viscosity Profile ◽  
The Impact ◽  
Tight Rocks

Abstract It has been frequently hypothesized that there is an “effective immobile layer” attached at the solid-liquid interface to represent the hindering effect because of the complicated composition on the flow of crude oil in nanopores. Nevertheless, the resulting viscosity discontinuity is physically problematic, and the effect of viscosity transition was not incorporated. In this paper, based on the reduced form of the continuous viscosity profile, the numerical and analytical models for reduced velocity profiles (quantifying the magnitude and the shape) and the reduced pore radius (the ratio of equivalent and actual pore radii) are obtained and compared with each other, respectively. The reduced pore radius establishes a link between the “effective immobile layer” simplification and the viscosity transition. Detailed sensitivity analysis is conducted to study the impact of viscosity transition (indicated by the curvature constant and the viscosity ratio) on the reduced viscosity profile, reduced velocity profiles and the reduced pore radius, separately. Results show the microscale flow patterns that cannot be reflected by the existing body of methodology. This work is important for understanding the flow characteristics of crude oil in shale and tight rocks, where nanopores are dominating and the effect of the interfacial viscosity transition can be significant.

scholarly journals Reinvestigating the Parabolic-Shaped Eddy Viscosity Profile for Free Surface Flows

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 126
Author(s):  
Rafik Absi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Velocity Profile ◽  
Eddy Viscosity ◽  
Velocity Profiles ◽  
Free Surface Flows ◽  
Analytical Models ◽  
Surface Flows ◽  
Viscosity Models ◽  
Viscosity Profile

The flow in rivers is turbulent. The main parameter related to turbulence in rivers is the eddy viscosity, which is used to model a turbulent flow and is involved in the determination of both velocities and sediment concentrations. A well-known and largely used vertical distribution of eddy viscosity in free surface flows (open channels and rivers) is given by the parabolic profile that is based on the logarithmic velocity profile assumption and is valid therefore only in the log-law layer. It was improved thanks to the log-wake law velocity profile. These two eddy viscosities are obtained from velocity profiles, and the main shortcoming of the log-wake profile is the empirical Coles’ parameter. A more rigorous and reliable analytical eddy viscosity model is needed. In this study, we present two analytical eddy viscosity models based on the concepts of velocity and length scales, which are related to the exponentially decreasing turbulent kinetic energy (TKE) function and mixing length, namely, (1) the exponential-type profile of eddy viscosity and (2) an eddy viscosity based on an extension of von Karman’s similarity hypothesis. The eddy viscosity from the second model is -independent, while the eddy viscosity from the first model is -dependent (where is the friction Reynolds number). The proposed analytical models were validated through computation of velocity profiles, obtained from the resolution of the momentum equation and comparisons to experimental data. With an additional correction function related to the damping effect of turbulence near the free surface, both models are similar to the log-wake-modified eddy viscosity profile but with different values of the Coles’ parameter, i.e., for the first model and for the second model. These values are similar to those found in open-channel flow experiments. This provides an explanation about the accuracy of these two analytical models in the outer part of free surface flows. For large values of ( > 2000), the first model becomes independent, and the two coefficients reach asymptotic values. Finally, the two proposed eddy viscosity models are validated by experimental data of eddy viscosity.

Drag Reduction and Velocity Profiles Distribution of Crude Oil Flow in Spiral Pipes

2015 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
Yanuar Yanuar ◽  
Kurniawan T. Waskito ◽  
Gunawan Gunawan ◽  
Budiarso Budiarso
Keyword(s):  
Drag Reduction ◽  
Crude Oil ◽  
Velocity Profiles ◽  
Oil Flow

Determinants of Inflation in Vietnam: A VECM Approach

2015 ◽  
Vol 22 (04) ◽  
pp. 26-50
Author(s):  
Ngoc Tran Thi Bich ◽  
Huong Pham Hoang Cam
Keyword(s):  
Interest Rate ◽  
Crude Oil ◽  
Error Correction ◽  
Budget Deficit ◽  
Oil Prices ◽  
Crude Oil Prices ◽  
Domestic Credit ◽  
Short Run ◽  
The Impact

This paper aims to examine the main determinants of inflation in Vietnam during the period from 2002Q1 to 2013Q2. The cointegration theory and the Vector Error Correction Model (VECM) approach are used to examine the impact of domestic credit, interest rate, budget deficit, and crude oil prices on inflation in both long and short terms. The results show that while there are long-term relations among inflation and the others, such factors as oil prices, domestic credit, and interest rate, in the short run, have no impact on fluctuations of inflation. Particularly, the budget deficit itself actually has a short-run impact, but its level is fundamentally weak. The cause of the current inflation is mainly due to public's expectations of the inflation in the last period. Although the error correction, from the long-run relationship, has affected inflation in the short run, the coefficient is small and insignificant. In other words, it means that the speed of the adjustment is very low or near zero. This also implies that once the relationship among inflation, domestic credit, interest rate, budget deficit, and crude oil prices deviate from the long-term trend, it will take the economy a lot of time to return to the equilibrium state.

Evaluation of Hydraulic Fracturing Models and Their Limitations to Predict No-Drill Zones for Horizontal Directional Drilling

2018 ◽  
Author(s):  
Saeed Delara ◽  
Kendra MacKay
Keyword(s):  
Hydraulic Fracturing ◽  
Safety Factor ◽  
Standard Procedure ◽  
Accurate Determination ◽  
Strength Properties ◽  
Analytical Models ◽  
Alternative Methods ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
The Impact

Horizontal directional drilling (HDD) has become the preferred method for trenchless pipeline installations. Drilling pressures must be limited and a “no-drill zone” determined to avoid exceeding the strength of surrounding soil and rock. The currently accepted industry method of calculating hydraulic fracturing limiting pressure with application of an arbitrary safety factor contains several assumptions that are often not applicable to specific ground conditions. There is also no standard procedure for safety factor determination, resulting in detrimental impacts on drilling operations. This paper provides an analysis of the standard methods and proposes two alternative analytical models to more accurately determine the hydraulic fracture point and acceptable drilling pressure. These alternative methods provide greater understanding of the interaction between the drilling pressures and the surrounding ground strength properties. This allows for more accurate determination of horizontal directional drilling limitations. A comparison is presented to determine the differences in characteristics and assumptions for each model. The impact of specific soil properties and factors is investigated by means of a sensitivity analysis to determine the most critical soil information for each model.

An improved de Laval nozzle experiment

2021 ◽  
pp. 030641902110341
Author(s):  
Nicholas Goodman ◽  
Brian J Leege ◽  
Peter E Johnson
Keyword(s):  
Data Acquisition ◽  
Laval Nozzle ◽  
Flow Characteristics ◽  
Data Acquisition System ◽  
Isentropic Flow ◽  
Hands On ◽  
De Laval Nozzle ◽  
Physical Phenomena ◽  
The Impact ◽  
The Relationship

Exposing students to hands-on experiments has been a common approach to illustrating complex physical phenomena that have been otherwise modelled solely mathematically. Compressible, isentropic flow in a duct is an example of such a phenomenon, and it is often demonstrated via a de Laval nozzle experiment. We have improved an existing converging/diverging nozzle experiment so that students can modify the location of the normal shock that develops in the diverging portion to better understand the relationship between the shock and the pressure. We have also improved the data acquisition system for this experiment and explained how visualisation of the standing shock is now possible. The results of the updated system demonstrate that the accuracy of the isentropic flow characteristics has not been lost. Through pre- and post-laboratory quizzes, we show the impact on student learning as well.

The flow characteristics around bridge piers under the impact of a ship

2020 ◽  
Vol 32 (6) ◽  
pp. 1165-1177
Author(s):  
Yan-fen Geng ◽  
Hua-qiang Guo ◽  
Xing Ke
Keyword(s):  
Flow Characteristics ◽  
Bridge Piers ◽  
The Impact

scholarly journals Virus Transmission Risk in Urban Rail Systems: Microscopic Simulation-Based Analysis of Spatio-Temporal Characteristics

2021 ◽  
pp. 036119812110101
Author(s):  
Jiali Zhou ◽  
Haris N. Koutsopoulos
Keyword(s):  
Public Transportation ◽  
Virus Transmission ◽  
Flow Characteristics ◽  
Transportation Systems ◽  
Transmission Risk ◽  
Microscopic Simulation ◽  
Spatial And Temporal Patterns ◽  
Subway System ◽  
Public Transportation Systems ◽  
The Impact

The transmission risk of airborne diseases in public transportation systems is a concern. This paper proposes a modified Wells-Riley model for risk analysis in public transportation systems to capture the passenger flow characteristics, including spatial and temporal patterns, in the number of boarding and alighting passengers, and in number of infectors. The model is used to assess overall risk as a function of origin–destination flows, actual operations, and factors such as mask-wearing and ventilation. The model is integrated with a microscopic simulation model of subway operations (SimMETRO). Using actual data from a subway system, a case study explores the impact of different factors on transmission risk, including mask-wearing, ventilation rates, infectiousness levels of disease, and carrier rates. In general, mask-wearing and ventilation are effective under various demand levels, infectiousness levels, and carrier rates. Mask-wearing is more effective in mitigating risks. Impacts from operations and service frequency are also evaluated, emphasizing the importance of maintaining reliable, frequent operations in lowering transmission risks. Risk spatial patterns are also explored, highlighting locations of higher risk.

Investigation of suction flow characteristic in the inertance hydraulic converters for efficiency improvement

2021 ◽  
pp. 095965182110248
Author(s):  
Xiaoming Chen ◽  
Yuchuan Zhu ◽  
Travis Wiens ◽  
Doug Bitner ◽  
Minghao Tai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Flow Characteristic ◽  
Performance Indicator ◽  
Flow Characteristics ◽  
Check Valve ◽  
Analytical Models ◽  
Switching Frequency ◽  
Experimental Measurements ◽  
Efficiency Improvement ◽  
Suction Flow

The inertance hydraulic converter relies on fluid inertance to modulate flow or pressure and is considered to be a competitive alternative to the conventional proportional hydraulic system due to its potential advantage in efficiency. As the quantification of fluid inertance, the suction flow characteristic is the crucial performance indicator for efficiency improvement. To explore the discrepancy between the passive inertance hydraulic converter featured by the check valve and the active inertance hydraulic converter driven by an equivalent 2/3 way fast switching valve in regard to suction flow characteristics, analytical models of the inertance hydraulic converters were established in MATLAB/Simulink. The validated models of the respective suction components were incorporated in the overall analytical models and their suction flow characteristics were theoretically and experimentally discussed. The analytical predictions and experimental measurements for the current configurations indicated that the active inertance hydraulic converter yields a larger transient suction flow rate than that of the passive inertance hydraulic converter due to the difference of the respective suction components. The suction flow characteristic can be modulated using the supply pressure and duty cycle, which was confirmed by experimental measurements. In addition, the suction flow characteristics are heavily affected by the resistance of the suction flow passage and switching frequency. There is a compromise between the resistance and switching frequency for inertance hydraulic converters to achieve large suction flow rate.

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