Investigation of Compaction and Sand Migration Effect on Permeability and Non-Darcy Coefficient With Pore-Scale Simulations

2015 ◽  
Author(s):  
Sultan Anbar ◽  
Mayank Tyagi ◽  
Karsten Thompson
Keyword(s):  
Flow Direction ◽  
High Rate ◽  
Sand Particle ◽  
Permeability Change ◽  
Inertial Effects ◽  
Pore Throat ◽  
Fines Migration ◽  
Porosity Reduction ◽  
Type Relation ◽  
Permeability Impairment

Compaction and sand migration are some of the main problems for the loosely consolidated and unconsolidated high rate gas reservoirs. A reliable estimation of the well productivity depends on accurate modeling of permeability and inertial effects. Therefore, the key objective of this paper is to quantify the flow parameters change in the case of compaction and sand migration, and the development of permeability and the non-Darcy coefficient correlations that can be used in reservoir simulations. The compaction effects are simulated by increasing grains diameters with the same ratio. Permeability and the non-Darcy coefficients are calculated from lattice Boltzmann method (LBM). Results indicate that permeability decrease is not directional and the change in permeability can be estimated from porosity change with a Kozeny-Carman type relation with an exponent of 3.2. A Kozeny-Carman type relation between the non-Darcy coefficient and permeability is also found with an exponent −1.303. For high compressibility reservoirs, estimation of the inertial effects from the correlations developed as a function of permeability and porosity may also lead to underestimation of the inertial effects. Sand migration causes pore-throat plugging that leads to significant reduction in permeability. Permeability impairment due to sand or fines migration is usually estimated from Kozeny-Carman type relation based on porosity. There is no study in the literature on how the inertial effects are changed with permeability impairment due to sand or fines migration. Sand particle plugging locations are found from the network simulations for different pore volume reduction, and corresponding permeability and the non-Darcy coefficient are calculated from LBM. It is found that permeability change with sand plugging is direction dependent: permeability reduction in the flow direction is twice compared to other directions. Porosity reduction does not depend on only pore-throat plugging, porosity can be decrease due to compaction and pore-surface deposition. Therefore, a correlation is developed to estimate permeability from pore-throat sand concentration. Even though permeability change is directional, the trend between permeability and the non-Darcy coefficient is similar and the magnitude of exponent in Kozeny-Carman type relation is larger, −1.803, compared to that of compaction.

Successfully Optimizing Breakers in Polyacrylamides for Slickwater and High-Viscosity Fluids

2021 ◽  
Author(s):  
Sarkis Kakadjian ◽  
Jarrett Kitchen ◽  
Amanda Flowers ◽  
John Vu ◽  
Amanuel Gebrekirstos ◽  
...  
Keyword(s):  
Light Scattering ◽  
Active Material ◽  
High Viscosity ◽  
High Rate ◽  
Viscosity Reduction ◽  
Superior Performance ◽  
Size Distributions ◽  
Pore Throat ◽  
Eagle Ford ◽  
Fracture Conductivity

Abstract Polyacrylamide-based friction reducers (FR's) - including viscosifying polyacrylamides, which are designed to decrease proppant settling by increasing molecular weight and/or active material in the FR - are used extensively in high-rate fracture stimulations. However, because polyacrylamides are difficult to break, there have been concerns about how these materials impact fracture conductivity and formation permeability. This study presents the effect of conventional and novel oxidative breakers over the viscosity and colloidal size distribution of the broken polymers. Breakers tested include conventional persulfates, perborates and patent pending peroxides, all of which generate free radicals to degrade partially hydrolyzed polyacrylamides (PHPAs). Breakers were tested at bottomhole temperatures encountered in the Permian, Bakken, Haynesville and Eagle Ford. Changes to PHPA viscosity were determined using vibrational viscometers. Size distributions and percentage of the broken colloidal PHPA were determined by dynamic light scattering. This method can measure sizes down to 0.6 nanometers, which is within the range of even the smallest pore-throat sizes in shales. Light scattering revealed surprising anomalies in breaker performance. When aged at temperatures typical of the Permian, each of the tested breakers at each of the varied concentrations caused similar levels of viscosity reduction but different size distributions. Some breakers had the unwanted effect of narrowing the colloidal size fractions to the lower end of the spectrum. At these small sizes, colloids are more likely to overlap with segments of the pore throat distribution in some shales, which could inhibit production. In addition, when the FR was aged at the higher temperatures encountered in the Bakken, Eagle Ford and Haynesville, some breakers were not able to uniformly break the PHPA. In these cases, FR's without breakers delivered superior performance. The results clearly demonstrate that breakers may not always have the desired effect of increasing the formation's permeability. In fact, depending on the type of breaker and the concentration, they can often have detrimental effects that ultimately hinder production.

scholarly journals Numerical Analysis of Liquid Mixing in a T-Micromixer with Taylor Dispersion Obstructions

2019 ◽  
Vol 5 (1) ◽  
pp. 147-160
Author(s):  
T. Manoj Dundi ◽  
S. Chandrasekhar ◽  
Shasidar Rampalli ◽  
V. R. K. Raju ◽  
V. P. Chandramohan
Keyword(s):  
Biomedical Engineering ◽  
Flow Direction ◽  
Taylor Dispersion ◽  
Chaotic Advection ◽  
Mixing Enhancement ◽  
Chemical Processing ◽  
Inertial Effects ◽  
Mixing Performance ◽  
Velocity Gradients

Passive micromixers are of great importance in biomedical engineering (lab-on-chips) and chemical processing (microreactors) fields. Various hydrodynamic principles such as lamination, flow separation, and chaotic advection were employed previously to improve mixing in passive mixers. However, mixing enhancement due to velocity gradients in the flow, which is known as the Taylor dispersion effect, has been seldom studied. In the present study, thin rectangular slabs oriented in the flow direction are placed in the mixing channel of a T-micromixer. The thin rectangular slabs are referred to as Taylor Dispersion Obstructions (TDOs) as they are designed to create velocity gradients in the flow. The mixing performance of T-micromixer with and without TDOs is estimated in the Re range of 0 to 350. It is observed that there is no effect on mixing in the presence of TDOs in the low Re (0 < Re < 100), as the velocity gradients created in the flow are considerably small. The vortex formed in the flow for Re of 100 to 220 damped the gradients of velocity created in the flow (due to the presence of TDOs) which resulted in negligible improvement in the quality of mixing. However, considerable enhancement in mixing performance is obtained at high Re (250 to 350) with the presence of TDOs in the mixer. The increase in inertial effects at higher Recreated larger gradients of velocity near the walls of TDOs and mixing channel walls and thereby a significant enhancement in mixing performance is obtained due to Taylor dispersion.

Cutting Process Simulation in Micro Dimple Machining

2019 ◽  
Author(s):  
Takashi Matsumura ◽  
Yuji Musha
Keyword(s):  
Cutting Forces ◽  
Rotation Axis ◽  
Flow Direction ◽  
Mechanistic Model ◽  
Cutting Parameters ◽  
Process Models ◽  
Cutting Process ◽  
High Rate ◽  
Force Model ◽  
Micro Dimple

Abstract The paper discusses micro dimple millings with inclined ball end mills. Cutting process models are presented to control the dimple shapes and predict the cutting forces. In micro dimple milling, the cutter rotation axis is inclined to have the non-cutting time, during which the cutting edges don’t remove the material in a rotation of cutter. The end mill is fed at a high rate so that the machining areas removed by the cutting edges are not overlapped each other. The shapes and the alignment of the dimples are simulated for the cutting parameters in the mechanistic model. Then, the cutting forces are predicted for high machining accuracies. The cutting experiments were conducted to verify the micro dimple machining. The dimple shape model is validated in comparison between the simulated and the actual dimple shapes. The cutting forces are simulated to compare the measured ones. The force model works well to predict the cutting forces with the chip flow direction during a rotation of the cutter.

Numerical Study on Aeolian Sand Ripples Forming and Moving Process in Desert Highway

2011 ◽  
Vol 462-463 ◽  
pp. 1032-1037 ◽  
Author(s):  
Abdurahman Ablimit ◽  
Mamtimin Gheni ◽  
Zhong Hua Xu ◽  
Mamatjan Tursun ◽  
Xamxinur Abdikerem
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Numerical Models ◽  
Flow Direction ◽  
Sand Particle ◽  
Forming Process ◽  
Sand Surface ◽  
Airflow Field ◽  
Sand Flow ◽  
Desert Highway

In this paper, the sand break into highway problem in desert, which is caused by the sand flow blown by wind, is studied. The mathematical models are introduced by considering the fixed, semi-fixed and free sand desert fields based on the fluid dynamics and the sand particle dynamics. Different kinds of numerical models are made by changing the desert highway height, wind flow direction and its uniformity. The weak coupling method is used due to spatial relationships between air flow field and the sand flow field. Finally, by coupling the airflow field and sand flow field with desert highway, the numerical simulations of sand forming process on desert highway are conducted. The numerical results shown, that the wind blown sand breaks into highway easier when wind direction perpendicular highway and if the highway height higher than the range size of the sand surface the wind blown sand break into highway is more difficult.

Determination of Dynamic Fracture Toughness Using Strain Measurement

2004 ◽  
Vol 261-263 ◽  
pp. 313-318 ◽  
Author(s):  
Duck Hoi Kim ◽  
Soon Il Moon ◽  
Jae Hoon Kim
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Strain Measurement ◽  
Charpy Impact ◽  
Dynamic Fracture Toughness ◽  
High Rate ◽  
Energy Methods ◽  
Inertial Effects ◽  
Optimum Response

By contrast with static fracture toughness determination, the methodology for dynamic fracture toughness characterization is not yet standardized and appropriate approaches must be devised. The accurate determination of the dynamic stress intensity factors must take into account inertial effects. Most methods for dynamic fracture toughness measurement are experimentally complex. However, dynamic fracture toughness determination using strain measurement is extremely attractive in terms of experimental simplicity. In this study, dynamic fracture toughness tests using strain measurement are performed. High rate tension and charpy impact tests are carried out for titanium alloy, maraging steel and Al alloys. In the case of evaluating the dynamic fracture toughness using high rate tension and charpy impact tests, load or energy methods are used commonly. The consideration about inertial effects is essential, because load or energy methods are influenced by inertia. In contrast, if the position for optimum response of strain is provided, dynamic fracture toughness evaluation using strain near crack tip is more accurate. To obtain the position for optimum response of strain, a number of gages were attached at angles of 60°. Reliability for experimental results is evaluated by Weibull analysis. The method presented in this paper is easy to implement in a laboratory and it provides accurate results compared to results from load or energy methods influenced by inertia.

Inertial Effects on Void Growth in Porous Viscoplastic Materials

1995 ◽  
Vol 62 (3) ◽  
pp. 633-639 ◽  
Author(s):  
W. Tong ◽  
G. Ravichandran
Keyword(s):  
Void Growth ◽  
Constitutive Models ◽  
Rate Sensitivity ◽  
High Rate ◽  
Dynamic Crack ◽  
Inertial Effects ◽  
Loading Conditions ◽  
Viscoplastic Material ◽  
Dynamic Loading Conditions ◽  
Very High

The present work examines the inertial effects on void growth in viscoplastic materials which have been largely neglected in analyses of dynamic crack growth and spallation phenomena using existing continuum porous material models. The dynamic void growth in porous materials is investigated by analyzing the finite deformation of an elastic/viscoplastic spherical shell under intense hydrostatic tensile loading. Under typical dynamic loading conditions, inertia is found to have a strong stabilizing effect on void growth process and consequently to delay coalescence even when the high rate-sensitivity of materials at very high strain rates is taken into account. Effects of strain hardening and thermal softening are found to be relatively small. Approximate relations are suggested to incorporate inertial effects and rate sensitivity of matrix materials into the porous viscoplastic material constitutive models for dynamic ductile fracture analyses for certain loading conditions.

scholarly journals Potential freshening impacts on fines migration and pore-throat clogging during gas hydrate production: 2-D micromodel study with Diatomaceous UBGH2 sediments

2020 ◽  
Vol 116 ◽  
pp. 104244
Author(s):  
Junbong Jang ◽  
Shuang C. Cao ◽  
Laura A. Stern ◽  
William F. Waite ◽  
Jongwon Jung ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Pore Throat ◽  
Fines Migration
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