scholarly journals Topological representation of the porous structure and its evolution of reservoir sandstone under excavation-induced loads

2017 ◽  
Vol 21 (suppl. 1) ◽  
pp. 285-292 ◽  
Author(s):  
Yang Ju ◽  
Yongming Yang ◽  
Xi Zhao ◽  
Feng Gao ◽  
Wei Song ◽  
...  
Keyword(s):  
Porous Structure ◽  
Numerical Models ◽  
Imaging Techniques ◽  
Reservoir Rock ◽  
Topological Model ◽  
Pore Characteristics ◽  
Deformation And Failure ◽  
Topological Parameters ◽  
Porous Sandstone ◽  
Compressive Loads

The porous structure of a reservoir rock greatly influences its evolutive deformation and fracture behavior during excavation of natural resources reservoirs. Most numerical models for porous structures have been used to predict the quasi-static mechanical properties, but few are available to accurately characterize the evolution process of the porous structure and its influence on the macroscopic properties of reservoir rocks. This study reports a novel method to characterize the porous structure of sandstone using its topological parameters and to determine the laws that govern the evolutive deformation and failure of the topological structure under various uniaxial compressive loads. A numerical model of the porous sandstone was established based on the pore characteristics that were acquired using computed tomography imaging techniques. The analytical method that integrates the grassfire algorithm and the maximum inscribed sphere algorithm was proposed to create the 3-D topological model of the deformed porous structure, through which the topological parameters of the structure were measured and identified. The evolution processes of the porous structure under various loads were characterized using its equivalent topological model and parameters. This study opens a new way to characterize the dynamic evolution of the pore structure of reservoir sandstone under excavation disturbance.

Application of Computational Intelligence in Generating Synthetic Reservoir Rock Mechanical Parameters for Building Geo-Models.

2015 ◽  
Author(s):  
L. C. Akubue ◽  
A.. Dosunmu ◽  
F. T. Beka
Keyword(s):  
Neural Network ◽  
Statistical Analysis ◽  
Numerical Models ◽  
Petroleum Industry ◽  
Oil Field ◽  
Wellbore Stability ◽  
Reservoir Rock ◽  
Rock Properties ◽  
Earth Model ◽  
Sonic Log

Abstract Oil field Operations such as wellbore stability Management and variety of other activities in the upstream petroleum industry require geo-mechanical models for their analysis. Sometimes, the required subsurface measurements used to estimate rock parameters for building such models are unavailable. On this premise, past studies have offered variety of methods and investigative techniques such as empirical correlations, statistical analysis and numerical models to generate these data from available information. However, the complexity of the relationships that exists between the natural occurring variables make the aforementioned techniques limited. This work involves the application of Artificial Neural Networks (ANNs) to generating rock properties. A three-layer back-propagation neural network model was applied predicting pseudo-sonic data using conventional wireline log data as input. Four well data from a Niger-Delta field were used in this study, one for training, one for validating and the two others for generating and testing results. The network was trained with different sets of initial random weights and biases using various learning algorithms. Root mean square error (RMSE) and correlation coefficient (CC) were used as key performance indicators. This Neural-Network-Generated-Sonic-log was compared with those generated with existing correlations and statistical analysis. The results showed that the most influential input vectors with various configurations for predicting sonic log were Depth-Resistivity-Gamma ray-Density (with correlating coefficient between 0.7 and 0.9). The generated sonic was subsequently used to compute for other elastic properties needed to build mechanical earth model for evaluating the strength properties of drilled formations, hence optimise drilling performance. The models are useful in Minimizing well cost, as well as reducing Non Productive Time (NPT) caused by wellbore instability. This technique is particularly useful for mature fields, especially in situations where obtaining this well logs are usually not practicable.

scholarly journals Dynamic Pulse Buckling of Composite Stanchions in the Sub-Cargo Floor Area of a Civil Regional Aircraft

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3594
Author(s):  
Andrea Sellitto ◽  
Francesco Di Caprio ◽  
Michele Guida ◽  
Salvatore Saputo ◽  
Aniello Riccio
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Low Frequency ◽  
Time Dependent ◽  
Structural Behavior ◽  
Cyclic Loads ◽  
Civil Aircraft ◽  
Compressive Loads ◽  
Pulse Buckling ◽  
Implicit And Explicit

This work is focused on the investigation of the structural behavior of a composite floor beam, located in the cargo zone of a civil aircraft, subjected to cyclical low-frequency compressive loads with different amplitudes. In the first stage, the numerical models able to correctly simulate the investigated phenomenon have been defined. Different analyses have been performed, aimed to an exhaustive evaluation of the structural behavior of the test article. In particular, implicit and explicit analyses have been considered to preliminary assess the capabilities of the numerical model. Then, explicit non-linear analyses under time-dependent loads have been considered, to predict the behavior of the composite structure under cyclic loading conditions. According to the present investigation, low-frequency cyclic loads with peak values lower than the static buckling load value are not capable of triggering significant instability.

scholarly journals Review of Sand Production Prediction Models

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Hossein Rahmati ◽  
Mahshid Jafarpour ◽  
Saman Azadbakht ◽  
Alireza Nouri ◽  
Hans Vaziri ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Prediction Models ◽  
Numerical Models ◽  
Element Model ◽  
Reservoir Rock ◽  
Sand Production ◽  
The Past ◽  
Short Period ◽  
Analytical Formulae ◽  
The Continuum

Sand production in oil and gas wells can occur if fluid flow exceeds a certain threshold governed by factors such as consistency of the reservoir rock, stress state and the type of completion used around the well. The amount of solids can be less than a few grams per cubic meter of reservoir fluid, posing only minor problems, or a substantial amount over a short period of time, resulting in erosion and in some cases filling and blocking of the wellbore. This paper provides a review of selected approaches and models that have been developed for sanding prediction. Most of these models are based on the continuum assumption, while a few have recently been developed based on discrete element model. Some models are only capable of assessing the conditions that lead to the onset of sanding, while others are capable of making volumetric predictions. Some models use analytical formulae, particularly those for estimating the onset of sanding while others use numerical models, particularly in calculating sanding rate. Although major improvements have been achieved in the past decade, sanding tools are still unable to predict the sand mass and the rate of sanding for all field problems in a reliable form.

THE RANDOM POROUS STRUCTURE AND MECHANICAL RESPONSE OF LIGHTWEIGHT ALUMINUM FOAMS

2014 ◽  
Vol 1662 ◽  
Author(s):  
Max Larner ◽  
John Acker ◽  
Lilian P. Dávila
Keyword(s):  
Mechanical Properties ◽  
Porous Structure ◽  
Relative Density ◽  
Testing Machine ◽  
Sound Insulation ◽  
Full Potential ◽  
Open Cell ◽  
Compressive Loads ◽  
Al Foam ◽  
Al Foams

ABSTRACTLightweight porous foams have been of particular interest in recent years, since they have a very unique set of properties which can be significantly different from their solid parent materials. These properties arise from their random porous structure which is generated through specialized processing techniques. Their unique structure gives these materials interesting properties which allow them to be used in diverse applications. In particular, highly porous Al foams have been used in aircraft components and sound insulation; however due to the difficulty in processing and the random nature of the foams, they are not well understood and thus have not yet been utilized to their full potential. The objective of this study was to integrate experiments and simulations to determine whether a relationship exists between the relative density (porous density/bulk density) and the mechanical properties of open-cell Al foams. Compression experiments were performed using an Instron Universal Testing Machine (IUTM) on ERG Duocel open-cell Al foams with 5.8% relative density, with compressive loads ranging from 0-6 MPa. Foam models were generated using a combination of an open source code, Voro++, and MATLAB. A Finite Element Method (FEM)-based software, COMSOL Multiphysics 4.3, was used to simulate the mechanical behavior of Al foam structures under compressive loads ranging from 0-2 MPa. From these simulated structures, the maximum von Mises stress, volumetric strain, and other properties were calculated. These simulation results were compared against data from compression experiments. CES EduPack software, a materials design program, was also used to estimate the mechanical properties of open-cell foams for values not available experimentally, and for comparison purposes. This program allowed for accurate prediction of the mechanical properties for a given percent density foam, and also provided a baseline for the Al foam samples tested via the IUTM method. Predicted results from CES EduPack indicate that a 5.8% relative density foam will have a Young’s Modulus of 0.02-0.92 GPa while its compressive strength will be 0.34-3.37 MPa. Overall results revealed a relationship between pores per inch and selected mechanical properties of Al foams. The methods developed in this study can be used to efficiently generate open-cell foam models, and to combine experiments and simulations to calculate structure-property relationships and predict yielding and failure, which may help in the pursuit of simulation-based design of metallic foams. This study can help to improve the current methods of characterizing foams and porous materials, and enhance knowledge about theirproperties for novel applications.

Numerical Analysis of Deformation and Failure of Penetration into Concrete Target by Projectile

2013 ◽  
Vol 804 ◽  
pp. 292-297 ◽  
Author(s):  
Song Gao ◽  
Ya Bin Wang ◽  
Xiu Feng Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Shear Failure ◽  
Failure Strain ◽  
Numerical Models ◽  
Experimental Results ◽  
Deformation And Failure ◽  
Material Parameters ◽  
The Military ◽  
Protection Engineering

Penetration is an important topic in the military and protection engineering field. Based on *MAT_PLASTIC_KINEMATIC of LS-DYNA program, this report studies effects of failure strain of the material parameters on structure of penetrating projectile. By establishing a group of numerical models about 45 steel hemispherical projectile penetrating semi-infinite concrete targets, this research aimed at analyzing effects of different failure strain values related to the destruction of the internal bracket structures of this projectile. At the same time, it studied the criterion of failure on finite dynamic program. The numerical results show that the use of failure strain in this model can well simulate damage of internal bracket structures of the projectile. Test was carried on based on this conclusion, which showed that bracket plate is subjected to shear failure in process of penetration, and numerical simulation was consistent with the experimental results.

Post-Cracking FRCM Strengthening of an Arch Composed by Hollow Clay Elements Embedded in Mortar: Experimental Investigations and Numerical Analyses

2017 ◽  
Vol 747 ◽  
pp. 142-149 ◽  
Author(s):  
Simone Tiberti ◽  
Carmelo Scuro ◽  
Rosamaria Codispoti ◽  
Renato S. Olivito ◽  
Gabriele Milani
Keyword(s):  
Roman Empire ◽  
Numerical Models ◽  
Mediterranean Area ◽  
Elementary Cell ◽  
Numerical Analyses ◽  
Laboratory Model ◽  
Experimental Investigations ◽  
Uniaxial Tensile ◽  
Structural Elements ◽  
Compressive Loads

The use of hollow clay elements (fictile tubules, amphorae and caroselli) for erecting arches, vaults and domes was a building technique very popular in the Mediterranean area from the Roman Empire on. It was devised to ensure lightness and thermal insulation of structural elements. This paper presents experimental investigations and some preliminary numerical analyses regarding an arch consisting of caroselli embedded in mortar. A full-scale laboratory model was constructed and subject to vertical loads. After the development of hinges, the arch was repaired and strengthened with FRCM strips and further loads were applied to investigate the post-strengthening mechanical behavior. Also, numerical models of caroselli and mortar are created in Abaqus. Then, an elementary cell comprised of caroselli and mortar is created. The mechanical properties of the cell are evaluated by studying its behavior under uniaxial tensile and compressive loads. These properties set the basis for a possible homogenized material which can be used for numerical analyses of the arch.

scholarly journals Numerical simulation of fatigue failure of composite materials under compression

2019 ◽  
Vol 221 ◽  
pp. 01040
Author(s):  
Mark Petrov
Keyword(s):  
Numerical Simulation ◽  
Composite Materials ◽  
Reaction Rates ◽  
Metal Alloys ◽  
Carbon Fibres ◽  
Deformation And Failure ◽  
Reinforced Plastic ◽  
Compressive Loads ◽  
Local Plastic Deformation ◽  
Thermodynamic Processes

The process of fatigue fracture of carbon fibres reinforced plastic under compressive loads is considered from the standpoint of the theory of reaction rates. Numerical simulation is based on rheological structural models of the material, which reproduce thermodynamic processes of local plastic deformation and failure occurring in time. The prediction of longevity of composite materials under compressive loads is similar to the solution of the problem for metal alloys under tensile loads when temperature and stresses are arbitrary functions of time.

Multiscale Modeling of the Blood Circulation in the Human Liver Using Vascular Corrosion Casting and Micro-CT Imaging Techniques

2011 ◽  
Author(s):  
Charlotte Debbaut ◽  
Diethard Monbaliu ◽  
Christophe Casteleyn ◽  
Pieter Cornillie ◽  
Denis Van Loo ◽  
...  
Keyword(s):  
Blood Circulation ◽  
Numerical Models ◽  
Imaging Techniques ◽  
Organ Transplant ◽  
Diagnostic Techniques ◽  
Corrosion Casting ◽  
Micro Ct ◽  
Contrast Enhanced ◽  
Branching Patterns ◽  
Vascular Trees

Numerical models to analyze blood flow may be important for a better understanding of organ hemodynamics and (dys)function (e.g. in organ transplant research), and diagnostic techniques (e.g. contrast-enhanced MRI to characterize tumors). Existing models of (liver) vascular trees are predominantly based on idealized models using fractional calculus to describe bifurcating branching patterns. In contrast, we previously developed an electrical analog model of the human hepatic circulation, based on measured data of the macrocirculation and extrapolated data of the microcirculation [1]. Furthermore, the microcirculation is usually modeled as a porous medium [2].

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