bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the Regression Modeling Method in Assessing Changes and Predicting the Physical Status of the Russian Population
Authors: Timonin A. N. , Burlyaeva E. A. , Nikitin N. S. , Klochkova S. V. , Nikityuk D. B.
Published: April 2019

The aim of the study was to perform regression modeling of the physical status of the Russian population from 1917 to 2017 and to build a prognostic model until 2035.

Material and methods. The methodological approach was based on the methods of correlation and regression analysis, namely, on the construction of linear regression models. Data collection was based on the archival historical documents. Statistical data were processed using SPSS and Excel. The significance level was assumed to be 0.05.

Results. The basic regression models for each of the studied parameters were formulated in the study. In accordance with the given regression models, the authors made a forecast for all the studied parameters up to 2035.

Conclusion. This method can be considered as a promising methodological tool in the study of the dynamic series of relevant parameters in identifying not only the tendency, but also the hidden oscillatory component of the series.
The Managerial Experience: a New Challenge for Firms
Authors: Mamadou Sylla
Published: April 2019

The objective of this article is to analyze the management system, which is the second part of any approach to promoting managerialism. Hence, the managerial experience must allow the manager to learn in his work situation in the extension of the development devices. Focused on concrete experience and active experimentation of the learning process. The managerial experience must guarantee the manager a minimum of coherence between the main characteristics of his work situation and the requirements of the transformation of his experience into competence. Any approach can thus advantageously begin with a managerial audit to identify the factors favorable and unfavorable to his managerial learning. But, the new stake for pre-crisis firms must satisfy the three major players represented by its customers, its staff and its shareholders. Today, companies must reinvent themselves to take into account the emergence of a new priority: their environment in the broad sense. They must now try to gain qualities such as being socially responsible, ecologically adult and morally exemplary. Also, a perspective and prospective vision on the post-crisis: the purpose of this article is primarily to provide leaders of firms, concrete management solutions and benchmarks for navigating in turbulent areas.
Notas literarias sobre sensibilidades y representaciones culturales de una Colombia marginada
Authors: van der Linde Carlos-Germán
Published: April 2019

El presente artículo parte del presupuesto de que la literatura es un producto cultural, y como tal ofrece claves de orden ético-estético para comprender signos culturales como los son las sensibilidades, representaciones, mentalidades e imaginarios de una sociedad. Con este presupuesto, se analizarán algunas novelas colombianas consideradas literatura urbana contemporánea; especialmente se han seleccionado aquellas que ofrecen alguna representación estética de situaciones de marginalidad. Del corpus seleccionado se estudiará el “sicario” en cuanto personaje literario, que vincularemos genéticamente con el “pícaro” del Siglo de Oro español, y que posteriormente se le ha reconocido como “sicaresco”. De éste se planteará su ethos en sentido crítico, por ejemplo, la marginalidad como una condición propicia para la experiencia del desarraigo, y su configuración como valor ético en la categoría “vagabundeo”, o la definición que pueda dársele al sicaresco según la toma de posición “desperanzada”.
Preference Neural Network
Authors: Elgharabawy Ayman , Parsad Mukesh , Lin Chin-Teng
Published: April 2019

This paper proposes a preference neural network (PNN) to address the problem of indifference preferences orders with new activation function. PNN also solves the Multi-label ranking problem, where labels may have indifference preference orders or subgroups are equally ranked. PNN follows a multi-layer feedforward architecture with fully connected neurons. Each neuron contains a novel smooth stairstep activation function based on the number of preference orders. PNN inputs represent data features and output neurons represent label indexes. The proposed PNN is evaluated using new preference mining dataset that contains repeated label values which have not experimented before. PNN outperforms five previously proposed methods for strict label ranking in terms of accurate results with high computational efficiency.
Investigation on the Effect of Cold Drawing Process on Mechanical Properties and Structure of Seamless Steel (Ck60) Tube
Authors: Niknamian Sorush
Published: April 2019

The cold drawing process is one of the precise metal forming techniques which have attracted attention by many researchers with respect to the given properties such as potential for improvement of mechanical properties of the material, achieving of accurate dimensional tolerances and rise of quality at final surface so that different studies are conducted on properties of various materials in the course of analysis of its effect. Using cold drawing and also exertion of special heat treatment cycle in this investigation, initially the seamless steel tube Ck60 has been produced and then effect of cold drawing has been assessed on the mechanical properties and structure of steel. The production process of seamless steel tube includes two phases of cold drawing which was followed by surface reduction levels 15.1% and 13.7% respectively. In order to analyze mechanical properties, tensile test and hardness-testing was used and metallography test was also employed to observe the structure. The given results indicate that the seamless steel tube Ck60 produced by means of this production process has ultimate tensile strength (1021 MPa), yield strength (950 MPa) and elongation (9%). Moreover, the value of hardness mean was 312 for the final tube in Vickers Hardness Test. The images taken from optical microscopy also show that the final structure of tube is uniform and as perlite ferrite.
Modelo de impacto orçamentário do rituximabe subcutâneo comparado ao intravenoso no tratamento do linfoma não Hodgkin difuso de grandes células B, CD-20 positivo, no sistema de saúde suplementar brasileiro
Authors: Kashiura Diego , Souza Paulo Vitor , Santos Henrique , Nardi Elene , Bueno de Sá Adriano , Santos Bárbara , Alves Marcia
Published: April 2019

Objetivo: Estimar o impacto orçamentário da introdução de rituximabe subcutâneo, comparado ao intravenoso, no sistema de saúde suplementar brasileiro, para o tratamento de linfoma não Hodgkin (LNH) difuso de grandes células B CD-20 positivo. Métodos: As perspectivas foram o sistema de saúde suplementar e operadoras de saúde de grande, médio e pequeno portes. Dados da Agência Nacional de Saúde Suplementar (ANS) foram utilizados para obter o número médio de pacientes por porte das operadoras e cruzados com dados epidemiológicos de LNH para estimar a população elegível. Uma pesquisa com 28 operadoras mapeou taxas, preços e tabelas de referência usadas para o reembolso de medicamentos, materiais e procedimentos. Uma equipe multidisciplinar estimou o uso de recursos. Os custos médicos diretos foram incluídos e os preços foram obtidos de fontes públicas. O horizonte temporal foi de cinco anos e considerou-se a incorporação progressiva de rituximabe subcutâneo com 20% no primeiro ano até atingir 100%. Resultados: Em cinco anos, 3.846 pacientes com LNH difuso foram estimados para o sistema de saúde suplementar, 35 para uma operadora de grande porte, 5 para uma de médio porte e 5 para uma de pequeno porte. Demonstrou-se que a incorporação de rituximabe subcutâneo pode economizar até R$ 15,8 milhões para todo o sistema, R$ 144,3 mil para uma operadora de grande porte e R$ 20,4 mil tanto para uma operadora de médio quanto para uma de pequeno porte. Conclusão: A incorporação de rituximabe subcutâneo no sistema de saúde suplementar brasileiro pode economizar até R$ 15,8 milhões no tratamento de LNH.
O diagnóstico por imagem no Brasil: um sistema, muitas realidades
Authors: Liebel Graziela , Reis de Sá Junior Antonio , Campos Estela Márcia , Loures Fabiano , Dias Patrick , Chaoubah Alfredo
Published: April 2019

Objetivos: A forma como os sistemas de saúde são financiados é um determinante crítico para alcançar a cobertura universal. Pouco foi publicado caracterizando padrões específicos do aumento preocupante de diagnóstico por imagem durante a última década. Este estudo objetivou verificar quais as variáveis socioeconômicas, estruturais e demográficas possuem associação com os gastos por diagnóstico de imagem ambulatorial de alta complexidade no Brasil. Esse tipo de análise pode permitir que os interessados em contenção de custos compreendam onde ocorre a maioria dos exames de imagens e a maior parte das despesas. Métodos: Os dados foram coletados de 2008 a 2016 do sistema Datasus com o uso do software TabWin versão 1.4.1. Resultados: O presente estudo mostrou que o aumento excessivo dos exames de imagem aumenta os custos e a exposição à radiação. Diversos fatores contribuíram para esse aumento, incluindo maior disponibilidade de tecnologia, aumento da demanda de pacientes e médicos, pagamento por produção e melhorias na tecnologia, resultando em maior facilidade no acesso aos exames de imagem. O estudo mostrou ainda que há concentração dos gastos per capita ambulatoriais com diagnóstico por imagem nas macrorregiões com melhor infraestrutura. Conclusões: É necessário um esforço mais concentrado para reduzir os custos administrativos. Ineficiências são provavelmente o produto de uma série de fatores, incluindo a complexidade administrativa do sistema de saúde do Brasil e a falta de transparência de custos em todo o sistema.
Macro Insights from Interval Pressure Transient Tests: Deriving Key Near-Wellbore Fracture Parameters in a Light Oil Reservoir Offshore Norway
Authors: Freites Alfredo , Corbett Patrick , Geiger Sebastian , Norgard Jens-Petter
Published: April 2019

Fractures can be first-order controls on fluid flow in hydrocarbon reservoirs. Understanding the characteristics of fractures such as their aperture, density, distribution, conductivity, connectivity, etc, is key for reservoir engineering and production analysis.

Well testing plays a key role in the the characterisation of fractured reservoirs, especially. New advances in the Pressure Transient Analysis (PTA) have enabled the interpretation of production data in a way where the resulting geological scenarios are in better agreement with fracture patterns observed in outcrop analogues.

Traditionally, Drill Stem Test (DST) data have been the primay source of information for well testing. However, we hypothesise that wireline conveyed tools designed for Interval Pressure Transient Testing (IPTT) could yield a more throrough description of the near-wellbore heterogeneities, including fractures.

Hence, we investigate the applicability of IPTT for characterising fractured reservoirs using detailed numerical simulations models with accurate wellbore representation to generate synthetic IPTT responses that can obtained through a next-generation wireline testing tool called SATURN. We particularly focus on cases where fractures are present in the near-wellbore region but do not intersect the wellbore. The study included parameters such as fracture densities and conductivities, distance between fractures and wellbore and the vertical extension of the fractures across geological beds.

The impact of the different fracture scenarios on the pressure transient tests was recorded as characteristic signatures on diagnostic plots (pressure derivative curves). We have called these curves "IPTT-Geotypes"; they can be used to assist the interpretation process of IPTT responses. To the best of our knowledge, this is the first time pressure derivative type curves for IPTT in fractured reservoirs are presented in the literature.

A field example of an IPTT case was analysed using the concept of geological well testing. We integrated the information from petrophysical logs and the IPTT-Geotypes to assist the calibration of a reservoir model developed to represent the geological setting of the tested reservoir interval. The results provided a sound interpretation of the reservoir geology and quantitative estimation of the matrix and fracture parameters.
A Bayesian Approach for Optimizing the Huff-n-Puff Gas Injection Performance in Shale Reservoirs Under Parametric Uncertainty: A Duvernay Shale Example
Authors: Hamdi Hamidreza , Clarkson Christopher R. , Esmail Ali , Costa Sousa Mario
Published: April 2019

Recent studies have indicated that Huff-n-Puff (HNP) gas injection has the potential to recover an additional 30-70% oil from multi-fractured horizontal wells in shale reservoirs. Nonetheless, this technique is very sensitive to production constraints and is impacted by uncertainty related to measurement quality (particularly frequency and resolution), and lack of constraining data. In this paper, a Bayesian workflow is provided to optimize the HNP process under uncertainty using a Duvernay shale well as an example.

Compositional simulations are conducted which incorporate a tuned PVT model and a set of measured cyclic injection/compaction pressure-sensitive permeability data. Markov chain Monte Carlo (McMC) is used to estimate the posterior distributions of the model uncertain variables by matching the primary production data. The McMC process is accelerated by employing an accurate proxy model (kriging) which is updated using a highly adaptive sampling algorithm. Gaussian Processes are then used to optimize the HNP control variables by maximizing the lower confidence interval (μ-σ) of cumulative oil production (after 10 years) across a fixed ensemble of uncertain variables sampled from posterior distributions.

The uncertain variable space includes several parameters representing reservoir and fracture properties. The posterior distributions for some parameters, such as primary fracture permeability and effective half-length, are narrower, while wider distributions are obtained for other parameters. The results indicate that the impact of uncertain variables on HNP performance is nonlinear. Some uncertain variables (such as molecular diffusion) that do not show strong sensitivity during the primary production strongly impact gas injection HNP performance. The results of optimization under uncertainty confirm that the lower confidence interval of cumulative oil production can be maximized by an injection time of around 1.5 months, a production time of around 2.5 months, and very short soaking times. In addition, a maximum injection rate and a flowing bottomhole pressure around the bubble point are required to ensure maximum incremental recovery. Analysis of the objective function surface highlights some other sets of production constraints with competitive results. Finally, the optimal set of production constraints, in combination with an ensemble of uncertain variables, results in a median HNP cumulative oil production that is 30% greater than that for primary production.

The application of a Bayesian framework for optimizing the HNP performance in a real shale reservoir is introduced for the first time. This work provides practical guidelines for the efficient application of advanced machine learning techniques for optimization under uncertainty, resulting in better decision making.
Five Years of Well Surveillance Pressure and Rate Data Guides Development of Tamar Field, Israel
Authors: Hebert Russell , Levitan Michael , Roberts Bill , Ortega Jesse , Bhatia Upasana
Published: April 2019

Tamar is a high permeability clastic gas reservoir that behaves like a well-connected tank, in many respects. At the same time, it has a significant level of complexity. The reservoir is comprised of three sand intervals, which are separated vertically by shales and broken into a number of fault blocks. While the degree of aquifer support has been an uncertainty, it is believed that the field demonstrates components of both bottom water and edge water drive.

All Tamar wells were equipped with permanent downhole pressure and temperature gauges, and the surveillance of these pressure and rate data over the five-year production history has provided an unusually comprehensive data set. This dataset supports the high-resolution evaluation of well interferences and multi-well analysis.

Investigation of the data on a well-by-well basis using conventional Pressure Transient Analysis techniques provided valuable insights, albeit primarily at the fault block scale. However, extending these investigations to the field scale generated some conflicting interpretations which could not be resolved by traditional PTA and standard reservoir engineering techniques.
Effects of Permeability and Wettability on CO2 Dissolution and Convection at Realistic Saline Reservoir Conditions: A Visualization Study
Authors: Amarasinghe Widuramina , Fjelde Ingebret , Rydland Jan-Aage , Guo Ying
Published: April 2019

When CO2 is injected to aquifers, CO2 will be dissolved into the water phase and react with rock minerals. The CO2 dissolution into the water phase initiated by the diffusion, will increase the density of the water- phase and thereby accelerate convective flow of CO2. The objective of the presented work was to study the effects of permeability and wettability of porous media by visual investigation of mixing of supercritical CO2 (sCO2) with water by convectional flow at realistic reservoir conditions (pressure and temperature). This required construction of a high-pressure transparent 2D-cell that allows visualization of CO2 transport, and development of experimental procedures.

To develop the high-pressure Hele-Shaw 2D-cell, stress/strain calculations and simulations were carried out to select the best building materials for realistic working pressure and temperature and required dimensions to study convection. Porous media was prepared by glass beads of different sizes giving different permeability and wettability. The experiments were carried out at 100 bars and 50 °C using deionized water solution with Bromothymol blue (BTB) as pH indicator.

In the constructed Hele-Shaw 2D-cell, the cell volume was formed by two glass plates separated by an adjustable spacer. The cell thickness was 5.0 mm in the present study. The high-pressure 2D-cell has made it possible to investigate CO2-dissolution and mixing with water at pressures and temperatures realistic for CO2-storage reservoirs.

CO2 mixing and finger development in the water phase without the presence of porous media, was an instantaneous process. The rate for CO2 dissolution and mixing with water was found to increase with increasing permeability for water-wet porous media. The CO2 dissolution pattern was found to depend on the permeability. Fingering of CO2 rich high-density water was observed with the high permeable porous media. Piston-like displacement was observed in lower permeable porous media. No significant effect of wettability was observed in the high-pressure 2D cell experiments. After experiments, it was confirmed that the wettability of the oil-wet particles was changed during the CO2 dissolution experiments.
A Novel Analytical Pressure-Transient-Analysis Approach for Compositional Two-Phase Flow during Gas Injection and Falloff
Authors: Machado Cíntia G. , Rafiee Javad , Reynolds Albert C.
Published: April 2019

In the petroleum industry, well testing is a common practice that consists of wellbore pressure, temperature and flow rates data acquisition to estimate parameters that govern the flow in porous media. Injection-falloff testing is particularly important for offshore reservoirs, especially for the oil reserves that contain high carbon dioxide and sulfur content. In this environment, a conventional well test in an exploratory well should not be run in order to avoid discarding high concentrations of these gases to the atmosphere. Therefore, there is a need for developing techniques for analyzing pressure data from injection-falloff tests. In this work, we have developed an approximate semi-analytical solution for wellbore pressure response during gas injection and falloff well tests in reservoirs containing oil and gas with complex composition by applying the Thompson and Reynolds steady-state theory. For the injection period, we first determine the overall concentrations distributions from a system of hyperbolic conservation equations using the method of characteristics (MOC), assuming a one-dimensional homogeneous reservoir with incompressible fluids and constant molar density, and neglecting capillary, gravity effects, volume changing on mixing and diffusion. During the falloff stage, it is assumed that there is no phase nor concentration movement in the reservoir, which is reasonable as we neglect capillary pressure, diffusion, gravity force and fluid compressibilities. Once we have the concentration profiles in the reservoir, we can calculate the total mobility distributions and then integrate the pressure gradient given by Darcy's law to find the wellbore pressure response. The semi-analytical approximate solution obtained was validated against the commercial numerical simulator STARS from CMG. After validation, the developed model was used as a forward model to estimate absolute permeability and skin factor by history matching noisy data obtained from the numerical simulator mentioned.
Enhanced Recovery of Heavy Oil by a Nano-Catalytic In-Situ Upgrading Process
Authors: Elahi Seyed Moein , Ahmadi Khoshooei Milad , Scott Carlos E. , Carbognani Ortega Lante , Chen Zhangxin , Pereira-Almao Pedro
Published: April 2019

Simultaneous in-reservoir upgrading and recovery of heavy oil are experimentally studied by using a continuous setup filled with carbonate cores. Upgrading reaction products as well as the recovered oil are analyzed in order to investigate the recovery mechanisms associated with this process.

In-situ upgrading technology (ISUT) is based on injection of high molecular weight (low quality) cut of oil, e.g., vacuum residue (VR), together with ultradispersed nano-catalyst and hydrogen. By injecting VR, catalyst, and hydrogen, the catalytic nano-particles deposit in the rock around an injection well, where the upgrading reactions occur. In this study, first, upgrading reactions happen inside a core packed container at the temperature, pressure, and residence time of 360 °C, 10 MPa, and 36 h, respectively. Subsequently, the hot reaction products are directed into another cylinder filled with carbonate cores to displace the heavy oil in place.

There are two main steps in a reservoir during ISUT. First, the injected VR is converted to lighter products during hydroprocessing reactions. Then the upgraded liquid and gaseous products along with hydrogen will displace the heavy oil toward production wells. At the conditions of this experiment in the reactor, 38 wt% of the VR cut is converted to lighter products with 1 wt% gases (mainly H2S and hydrocarbons with 1 to 5 carbon atoms) and 4.8 wt% naphtha cut (hydrocarbons with 5 to 12 carbon atoms). These light products act as solvents in the areas farther from the reaction zone and enhance the recovery of heavy oil. In addition, high temperatures, mechanical push, and rock matrix thermal expansion improve the oil displacement in the carbonate rock.

By enhancing the oil recovery and permanently upgrading heavy oil in one single stage, the need for diluent addition and steam generation is minimized, which makes ISUT economical and environmentally favorable. In an innovative experimental setup, both upgrading and recovery steps in the ISUT process are carefully analyzed.
An Integrated Sanding Study in an HP/HT Tight-Sandstone Gas Reservoir
Authors: Zhang Yang , Pan Yuanwei , Cui Xiaohu , Qiu Kaibin , Teng Qi , Huang Yongjie , Peng Fen
Published: April 2019

KS is a tight-sandstone and high-pressure-high-temperature (HPHT) gas reservoir in northwest China. It is characterized by a depth of more than 6000 m, temperature over 175°C, and pore pressure over 110 MPa. Despite the high unconfined compressive strength (UCS) of sandstone, almost half of the wells encountered sanding issues. The sanding wells exhibited low production rate, nozzle and pipeline erosion, sanding up, and even permanent closure. Investigating the sanding mechanism and developing solutions for sanding prevention are urgent needs due to the economic loss of low production.

An integrated sanding study was conducted to investigate the sanding mechanism. The entire sanding process was analyzed, including stress field alteration during production, rock failure, softening, and sand grain migration. First, wells with sanding issues were identified through production characteristics and field observation. After this, analysis of laboratory tests was performed to better understand the tight-sandstone properties, especially UCS, the softening parameter, and residual strength. Based on the tests, an elastoplastic damage model was proposed to delineate rock failure and sanding behavior. Then, a finite element model was built to simulate the damage of a perforation hole with field data, including hole diameter and length, rock stiffness and strength, drawdown, depletion, and so on. More simulation scenarios were performed to investigate the continuous sanding, transient sanding, and water hammer effect. Grain migration in perforation holes and in pipelines was also studied.

It was revealed that shear failure of perforation hole induced by drawdown and depletion was the root cause of sanding problem. Meanwhile, it was also confirmed that erosion and water hammer effect had very limited effect on sanding. Use of the elastoplastic damage model for the simulation of perforation hole failure enabled predicting the sand amount and determining the critical drawdown and depletion for sanding. In the end, an approach to identifying wells with high sanding risk and the key factors behind the sanding were provided, and sanding prevention suggestions were proposed.

The new elastoplastic damage model explains the sanding mechanism in a tight-sandstone reservoir and enables evaluating the sand volume, which has rarely been published previously. Laboratory tests, field observation, and numerical simulation were combined effectively to investigate the sanding issue. By utilizing the model, producers can find the key factors behind sanding issues, prevent sanding with a better production strategy, and avoid the economic loss, which are critical for the long-term exploration and production of this area.
Evaluation of Foam-Assisted Surfactant Flooding at Reservoir Conditions
Authors: Janssen Martijn , Mutawa Abdulaziz , Pilus Rashidah , Zitha Pacelli
Published: April 2019

Foam-Assisted Surfactant Flooding (FASF) is a novel enhanced oil recovery (EOR) method combining the reduction of oil-water (o/w) interfacial tension (IFT) to ultra-low values and foaming of a gas drive for mobility control. We present a detailed laboratory study on the FASF process at reservoir conditions. The stability of two specially selected surfactants in the vicinity of original injection water, i.e. sea water, at 90°C was assessed. The phase behaviour of the crude oil-surfactant-brine systems and the ability of the two selected surfactants to generate stable foam in bulk were studied in presence and in absence of crude oil. The phase behaviour and bulk tests resulted in the formulations of the surfactant slug and drive solutions. The slug solution aims for oil mobilisation by lowering of the o/w IFT and the drive formulation is required for gas foaming for mobility control. CT scanned core-flood experiments were conducted in Bentheimer sandstone cores initially brought to residual oil by water flooding. Oil mobilisation was obtained by injecting a surfactant slug at either under-optimum (o/w IFT of 10-2 mN/m) or optimum (o/w IFT of 10-3 mN/m) salinity conditions. At both salinities the injected surfactant slug yielded the formation of an unstable oil bank due to dominant gravitational forces. Optimum salinity surfactant slug was notably more effective at reducing residual oil to waterflood (81% reduction) compared to the under-optimum salinity slug (30% reduction). After oil mobilisation, drive foam was either generated in-situ by co-injection with nitrogen gas or was pre-generated ex-situ and then injected to displace mobilised oil. It was found that, at optimum salinity, FASF yielded an ultimate recovery factor of 40±5% of the oil in place (OIP) after water flooding whereas under-optimum salinity FASF showed a recovery of 35±7% of OIP after water flooding. Experiments have shown that the presence of crude oil is detrimental to in-situ foam generation and stability. Pre-generated drive foam increased its ultimate oil recovery by 13% of the OIP after water flooding compared to in-situ foam generation at optimum salinity.
An Investigation of the Performance of the Mimetic Finite Difference Scheme for Modelling Fluid Flow in Anisotropic Hydrocarbon Reservoirs
Authors: Hjeij Dawood , Abushaikha Ahmad
Published: April 2019

This paper investigates the performance of the mimetic finite difference (MFD) discretization scheme for modelling fluid flow in anisotropic porous media. We apply numerical benchmark studies on the MFD scheme to measure its accuracy when the horizontal permeability is much larger than the vertical one in a diagonal permeability tensor. We also run full-field simulations to investigate the modelling capability of this method and compare it to other advanced discretization schemes.
Multi-Scale Analysis of CO2 Injection as Improved Shale Gas Recovery Method
Authors: Kim Brice Y. , Olorode Olufemi , Akkutlu I. Yucel
Published: April 2019

This study is based on the premise that most of the trapped hydrocarbons can be produced, if we substitute them with another ‘acrificial’ fluid that has amplified interactions with organic pore walls, such as CO2. For the presented study, a downhole shale sample is analyzed in the laboratory to predict gas storage properties such as pore-volume, pore compressibility, and gas adsorption capacity. Then a series of pressure pulse decay measurements are performed to delineate transport mechanisms and predict stress-sensitive permeability. These coefficients are obtained as the calibration parameters of a simulation-based optimization for injection and production. Simulation model considers compositional gas flow in a deformable porous media and includes a multi-continuum porosity, with organic and inorganic pores, and micro-fractures. The experimental and simulation results show that most of the injected CO2 is adsorbed in the organic matrix and are not produced back. This is because CO2 molecules have significantly larger adsorption capacity when compared to methane. The strong adsorption of CO2 improves the release of natural gas from kerogen pores. This indicates that the separation of produced CO2 will be a minimal cost. Transport in kerogen has significant pore wall effects, and includes large mass fluxes of the adsorbed molecules by the walls due to surface diffusion. In essence, the adsorbed CO2 molecules significantly influence transport of methane. The results also show core-plug permeability is stress-sensitive due to presence of micro-fractures. Forward simulation results using optimum parameters indicate that closure stress developing near the fractures could significantly control the volume of CO2 injected. This raises operational issues on when to start injecting, and how to inject CO2. Using a simulation study of a production well with single-fracture, we show that fracture closure stress develops rapidly and production rate becomes a slave of the fracture geo-mechanics, e.g., strength of the proppants and the level of proppant embedment.
Impacts of Stress and Capillary End Effects on Relative Permeability of Shale Rocks
Authors: Nazari Moghaddam Rasoul , Jamiolahmady Mahmoud
Published: April 2019

Relative permeability (kr) functions are among the essential data required for the simulation of multiphase flow in hydrocarbon reservoirs. These functions can be measured in the laboratory using different techniques including the steady state displacement technique. However, relative permeability measurement of shale rocks is extremely difficult mainly because of the low/ultralow matrix permeability and porosity, dominant capillary pressure and stress-dependent permeability of these formations.

In this study, the impacts of stress and capillary end effects (CEE) on the measured relative permeability data were investigated. The steady state relative permeability (SS-kr) measurements were performed on Eagle Ford and Pierre shale samples. To overcome the difficulties regarding the kr measurements of shale rocks, a special setup equipped with a high-pressure visual separator (with an accuracy of 0.07 cc) was used. The kr data were measured at different total injection rates and liquid gas ratios (LGR). In addition, to evaluate the impacts of effective stress, the kr data of an Eagle Ford shale sample were measured at two different effective stresses of 1000 and 3000 psi.

From the experimental data, it was observed that the measured SS-kr data of the shale samples have been influenced by the capillary end effects as the data showed significant variation when measured at different injection rates (with the same LGR). This suggested that the liquid hold-up (i.e. capillary end effects) depends on the competition of capillary and viscous forces. In addition, it was shown that it is more necessary to correct the experimental kr data measured at the lower LGRs. Furthermore, different relative permeability curves were obtained when the kr data were measured at different effective stresses. This behavior was explained as the capillary pressure was expected to be more dominant at the higher effective stress.

The results from this study improve our understanding of unconventional mechanisms in shale reservoirs. It is evident that the behavior of unconventional reservoirs can be better predicted when more reliable and accurate relative permeability data are available. The outcomes of this study will be useful for accurate determination of such kr data.
Production Interference of Hydraulically Fractured Hydrocarbon Wells: New Tools for Optimization of Productivity and Economic Performance of Parent and Child Wells
Authors: Weijermars Ruud , Khanal Aadi
Published: April 2019

The present study provides a comprehensive set of new analytical expressions to help understand and quantify well interference due to competition for flow space between the hydraulic fractures of parent and child wells. Determination of the optimum fracture spacing is a key factor to improve the economic performance of unconventional oil and gas resources developed with multi-well pads. Analytical and numerical model results are combined in our study to identify, analyze, and visualize the streamline patterns near hydraulic fractures, using physical parameters that control the flow process, such as matrix permeability, hydraulic fracture dimensions and assuming infinite fracture conductivity. The algorithms provided can quantify the effect of changes in fracture spacing on the production performance of both parent and child wells. All results are based on benchmarked analytical methods which allow for fast computation, making use of Excel-based spreadsheets and Matlab-coded scripts. Such practical tools can support petroleum engineers in the planning of field development operations. The theory is presented with examples of its practical application using field data from parent and child wells in the Eagle Ford shale (Brazos County, East Texas). Based on our improved understanding of the mechanism and intensity of production interference, the fracture spacing (this study) and inter-well spacing (companion study) of multi-fractured horizontal laterals can be optimized to effectively stimulate the reservoir volume to increase the overall recovery factor and improve the economic performance of unconventional oil and gas properties.
Hydraulic Fractures Simulation and Stimulated Reservoir Volume Estimation for Shale Gas Fracturing
Authors: Lin Ran , Ren Lan , Zhao Jinzhou , Tao Yongfu , Tan Xiucheng , Zhao Jiangyu
Published: April 2019

Multi-stage & multi-cluster fracturing in horizontal well drilling is the core technology in for commercial exploitation of shale gas resevoir. According to vast field data, there is remarkable positive correlation relationship between stimulated reservoir volume (SRV) and shale gas production. Hence, estimating the SRV is essential for both pre-fracturing design and post-fracturing evaluation. However, the forming process of SRV involves with many complex mechanisms, making it is difficult to be simulated.

In this paper, we establish a mathematical model to estimate the SRV by simulating multiple hydraulic fractures propagate, formation stress change and reservoir pressure rise; consequently, the stress and pressure change might make natural fractures occur tensile failure or shear failure, generating a high-conductivity zone (i.e., SRV) in the shale reservoir.

To solve the model, displacement discontinuity method (DDM) is applied to simulate non-planar propagation of multiple hydraulic fractures and calculate formation stress change. Finite difference method (FDM) is used to compute reservoir pressure rise. The natural fractures failure state is determined by tensor formulae derived from Warpinski's failure theory. This SRV estimation method involves a variety of complex but crucial physical mechanisms during shale fracturing process which include unequal flow-rate distribution in different hydraulic fractures, non-planar hydraulic fractures propagation under stress interference, reservoir permeability increases with SRV expanding, two types of natural fracture failure and so on.

A field case study was performed to show the dynamic processes of hydraulic fractures propagation, reservoir permeability increase, and the SRV expansion during shale gas fracturing. Then we compared the simulation results with analytical solution, published papers and on-site microseismic monitoring data to verify our model. Finally, the influence of geological condition and engineering parameters on SRV was investigated by sensitivity analysis.
A Proper Data Comparison for Seismic History Matching Processes
Authors: Davolio Alessandra , Schiozer Denis José
Published: April 2019

Seismic data usually has lower vertical resolution than reservoir simulation models so it is a common practice to generate maps of 4D attributes to be used as the observed data to calibrate models. In such a case, simulation results are converted to seismic attributes and a map is generated by averaging the corresponding layers. Although this seems to be a fair practice, here we show that this procedure can present some drawbacks and propose a new approach to ensure a proper data comparison.

The first step of the proposed procedure follows the traditional sequence where seismic attributes are generated by running a petro-elastic model (PEM) with reservoir simulation data, at the simulation scale. Then, instead of averaging the simulation layers, we propose to resample the simulation grid to a seismic grid and filter the seismic impedances to the seismic frequency. Lastly, we extract the map from the regular grid to be compared with the observed 4D seismic. This procedure is performed in the depth domain and allows a straight and fair comparison of the two dataset.

A synthetic dataset based on a Brazilian field produced through water injection is used to validate this procedure. This dataset is composed by a synthetic 4D seismic data (observed data) generated by a consistent seismic modeling and inversion and a set of reservoir simulation models (to be matched). We computed seismic impedance for each simulation model by applying a PEM and two maps were generated for each model: (1) by averaging impedance values throughout the corresponding layers and (2) by applying the proposed procedure. When these maps are subtracted from the observed data (error maps), as would happen in a quantitative seismic history matching, we note a relevant differences. In the dataset used, we observed that if the vertical resolution issue is not considered (Case 1) the error map presents a strong bias that would erroneously force a decrease on the water saturation to match the observed data in a seismic history matching. While the map generated in Case 2 presents the errors better balanced and related to actual water movement differences rather than being a consequence of scale and resolution issues.

The novelty of this work is a quick way to bring simulation data to seismic resolution without going through all seismic modeling process ensuring a proper data comparison, which can be promptly added in seismic history matching process.
Mechanistic Simulation and History Matching of Alkaline-Surfactant-Polymer ASP Core Flooding Experiment at Optimum vs. Under-Optimum Salinity Conditions
Authors: Mirzaie Yegane Mohsen , Battistutta Elisa , Zitha Pacelli
Published: April 2019

Alkaline Surfactant Polymer (ASP) flooding is a chemical EOR method to increase oil recovery after water flooding through IFT reduction and increasing sweep efficiency. Previous studies have shown that maximal oil recovery is reached when ASP flooding is performed at optimum salinity conditions, i.e. Winsor type III micro-emulsion phase but a recently series of core-flood experiments indicated that comparable oil recovery could be obtained at under-optimum salinity conditions (Battistutta et al. 2015). Mechanistic simulation of ASP flooding considering phase behavior of water-oil-surfactant system, geochemical reactions and alkaline consumption is needed to validate the experimental data and provide a robust model for field scale studies. In this paper detailed history matching of series of core-flood experiments was attempted. Experiments were performed at different salinity conditions (optimum vs. under-optimum) and with different core types (Bentheimer and Berea) using a single olefin sulfonate (IOS) and crude oil with very low acid number (<0.05 mg KOH/g oil). The numerical simulations were performed using UTCHEM, multiphase multi-component simulator along with EQBATCH module to model the geochemical reactions.

Neglecting the effect of in-situ surfactant (soap) generation, since the acid number of crude oil was low, modeling of the phase behavior showed an excellent match against experimental data and optimal salinity was observed at 2.0 wt% NaCl (+ 2.0 wt% Na2CO3).Using this and considering aqueous and cation exchange as the most important geochemical reactions in alkaline propagation, several ASP core-flood experiments at optimum vs. under-optimum salinity conditions were successfully modeled. An excellent matching of all the measured parameters including oil cut and recovery, pressure drop, pH and carbonate, alkali and surfactant concentration at effluent was also achieved. Modeling confirms the results obtained from experiment which regardless of core type, although minimum achieved IFT at optimum salinity conditions is lower than the one achieved at under-optimum conditions, comparable final oil recovery was observed for both cases. This emphasizes the importance of performing ASP flooding at under-optimum salinity conditions due to lower surfactant retention and reducing the likelihood of achieving over-optimum salinity conditions.

In this paper a robust model which is calibrated with experimental data is presented to simulate ASP flood process at various conditions and the basic model can be used to perform further simulations and can provide practical and convenient approach to model field applications of ASP flooding.
Evaluating the Business and Owner Characteristics Influencing the Adoption of Online Advertising Strategies in the Green Industry
Authors: Torres Ariana P. , Barton Susan S. , Behe Bridget K.
Published: April 2019

As more individuals use the Internet for business and leisure, the opportunities for firms to promote products and services and to communicate with consumers online increases. The objective of this study was to investigate green industry managerial decisions to engage in online advertising and how much to invest while determining the main drivers contributing to these decisions. A double-hurdle model analyses of 1735 responses to the 2014 National Green Industry Survey, which gathered information on business practices, showed >40% of green industry business invested in online advertising. Typically, businesses investing in online advertising spent more than 43% of all advertising expenditures in online methods, including websites, social media, and newsletters. Furthermore, the decision to engage in online advertising was driven by the percentage of wholesale and contract sales, market access, firm size, product mix, and business owners’ perceptions. Results also showed that the amount of dollars invested in online advertising depended on firm size, tools used to find customers, location, and business owners’ perceptions. Our findings can help extension personnel and policymakers with the design and deliver social media training and educational events. Our findings can also help green industry businesses understand the two-step nature of the decision to invest in online advertising.
Doğal Afetlerin Çocuklar ve Ergenler Üzerindeki Etkileri
Authors: KARABULUT Derya , BEKLER Tolga
Published: April 2019

Doğal
afetler öngörülemeyen, etkileyeceği alan ve etki düzeyi tahmin edilemeyen, çok
fazla sayıda can ve mal kayıpları ile sonuçlanabilen doğa olaylarıdır. Dünya
genelinde ve ülkemizde her yıl birbirinden farklı doğal afetlerin yaşandığına
ve bu afetlerin sonuçlarının toplumlar üzerindeki etkilerine şahit oluyoruz. Çocuklar
ve ergenler afetlere maruz kalan ve afetlerden etkilenen grupların en hassas ve
savunmasız bireyleridir. Her yıl dünya üzerinde milyonlarca çocuk ve genç doğal
ve insan kaynaklı afetlere maruz kalmakta ve bu afetlerden farklı şekillerde
etkilenmektedir. Bu çalışma, doğal afetlerin çocuklar ve gençler üzerindeki
etkilerine yönelik farkındalık oluşturmak amacıyla yapılmıştır. Başta Yöktez, Google Scholar, Dergi Park, EM-DAT, Science Direct,
PubMed, Psikiyatri ve Psikoloji Araştırmaları Dergisi, Uluslararası Aile Çocuk
ve Eğitim Dergisi olmak üzere konu ile ilgili bilgi erişimini sağlayan veri
tabanları kullanılarak, afet, doğal afet, afet etkileri, afetler ve çocuklar,
afetler ve gençler, çocuk gelişimi araştırmamıza temel teşkil eden gruplar
kullanılarak elde edilen tezler ve makaleler irdelenmiştir. Konu ile
ilgili çalışmalar; ilerde yapılacak yeni araştırmalara veri tabanı olabilecek şekilde
genel olarak değerlendirilerek ve yorumlanarak bir araya getirilmiştir.