bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimización de la resistencia mecánica de cementos binarios MK/GBFS activados alcalinamente por Metodología de Superﬁcie de Respuesta
Authors: Gordillo Marisol , Rodríguez Erich D. , Mejía de Gutiérrez Ruby
Published: September 2015

El presente artículo muestra la modelación y optimización de la resistencia a la compresión de un conglomerante no convencional libre de cemento Portland, el cual fue producido a partir de la activación alcalina de una mezcla binaria de un metacaolín (MK) y una escoria siderúrgica de alto horno (GBFS). Como factores de estudio se consideró una relación GBFS/(GBFS/MK) entre 0,0-0,8 y una relación molar total SiO2=Al2O3 entre 2,8-4,2. La relación SiO2=Al2O3 fue ajustada a través de la contribución del precursor (MK+GBFS) y el activador alcalino. La evaluación estadística mediante la metodología de superficie de respuesta (MSR) mostró un efecto significativo entre la relación molar SiO2=Al2O3 y el contenido de GBFS sobre la resistencia a compresión. Complementariamente se desarrolló una caracterización microestructural a través de difracción de rayos X y microscopía electrónica de barrido. La incorporación de GBFS incrementó la cinética de reacción y la formación de una estructura más densa y compacta. Estos nuevos productos de reacción le otorgaron al material un mayor desempeño mecánico comparado con los constituidos con un 100% de MK.
Un algoritmo metaheurístico para el problema de localización y ruteo con flota heterogénea
Authors: Linfati Rodrigo , Escobar John Willmer , Gatica Gustavo
Published: September 2015

Consideramos el problema de localización y ruteo con flota heterogénea (LRPH, por sus siglas en inglés), en el cual se busca determinar los depósitos a ser abiertos, los clientes a ser asignados a cada depósito, y las rutas a ser construidas para satisfacer las demandas de los clientes, considerando una flota de vehículos con capacidad diversa y costos de utilización asociados. El objetivo es minimizar la suma de los costos asociados con la apertura de depósitos, los costos de los vehículos utilizados, y los costos variables directamente relacionados con las distancias recorridas. En este artículo, se propone un algoritmo metaheurístico basado en una búsqueda tabú granular para la resolución del problema. Experimentos computacionales en instancias adaptadas de la literatura, muestran que el algoritmo propuesto es capaz de obtener, en tiempos computacionales razonables, soluciones de alta calidad demostrando su efectividad.
Computational Study of Allotropic Structures of Carbon by Density Functional Theory (DTF)
Authors: Gonzalez Carmona Juan Manuel , Ruden Muñoz Alexander , Barbosa Christian , Ortega Portilla Carolina , Sequeda Osorio Federico
Published: September 2015

In this paper using Density Functional Theory (DFT), the principal carbonallo tropic crystalline structures (Diamond, graphite, nanotube y fullerene-C60) were simulated. The results shows diamond sp3 bonds formation between carbon atomsand low reactivity, indicating low probability of lateral compound formation and high mechanical properties. Interplanar weakness was evidentin graphite structure, which is related to solid lubrication process. Carbon-Carbon metallic bonds and polarizations at the edges of the structure were observed in Armchair Carbon Nanotube, stabilizing the system which allows the nanotube continuous growth. In fullerene C60structureaFaraday nano-gauge behavior was confirmed, together withlowprobability of interatomic polarization, indicating high structural stability. Besides Total Energy (TE) and Nuclear Repulsion Energy (NRE) values were used to perform energetic comparisons between different structures, allowing the study of electronic stability and their relationship to mechanical properties.
Aplicación de un modelo de balance poblacional a un molino de bolas en la industria del cemento
Authors: Rivera Ismael , Quintero Freddy , Bustamante Oswaldo , Loaiza G.
Published: September 2015

En este artículo se estudia un molino rotatorio continuo para la industria del cemento. Precisamente, se emplea un modelo de balance poblacional, utilizando como ecuación constitutiva una ley de desgaste constante, con el objetivo de obtener: la distribución másica de bolas en el molino, el consumo total de acero de las bolas y el flujo de entrada de bolas para la recarga del molino en el estado estacionario. La base de datos se obtuvo aplicando la prueba de bola marcada a escala industrial, en un molino de la compañía Argos S.A.
Structural and Morphological Properties of Titanium Aluminum Nitride Coatings Produced by Triode Magnetron Sputtering
Authors: Devia D.M. , Restrepo-Parra E. , Velez-Restrepo J.M.
Published: September 2015

Tix Al1−xN coatings were grown using the triode magnetron sputtering technique varying the bias voltage between -40 V and -150V. The influence of bias voltage on structural and morphological properties was analyzed by means of energy dispersive spectroscopy, x-ray diffraction and atomic force microscopy techniques. As the bias voltage increased, an increase inthe Al atomic percentage was observed competing with Ti and producing structural changes. At low Al concentrations, the film presented a FCC crystalline structure; nevertheless, as Al was increased, the structure pre-sented a mix of FCC and HCP phases. On the other hand, an increase inbias voltage produced a decrease films thickness due to an increase in colli-sions. Moreover, the grain size and roughness were also strongly influencedby bias voltage.
Diseño y construcción de un reactor mecatrónico para el crecimiento de películas delgadas por la técnica de recubrimiento por inmersión
Authors: Velásquez A. A. , Urquijo J. P. , Gutiérrez Y.
Published: September 2015

Se presenta el diseño y construcción de un sistema mecatrónico automatizado para el crecimiento de películas delgadas por la técnica de recubrimiento por inmersión. El sistema consta de un porta sustrato que realiza desplazamientos verticales entre dos posiciones ajustables. El movimiento del porta sustrato es controlado por una cadena de transmisión accionada por un motor de corriente continua. Los finales de recorrido del porta-sustrato son sensados por micro-switchs colocados en los extremos del intervalo de movimiento. La adquisición de la señal de los micro-switchs y la generación de la señal de control para el motor son realizadas por una tarjeta de adquisición de datos National Instruments USB 6353. Desde una interfaz gráfica desarrollada en LabVIEW el usuario puede programar todos los parámetros del reactor, entre ellos las velocidades de inmersión y extracción de los sustratos y el tiempo de secado. Se presentan detalles de la construcción y operación del sistema.
On the Problem of Transition from Executive (Teaching) Activity to Management: Conceptual Interpretation and Theoretical Model
Authors: Filinkova E.B.
Published: September 2015

The paper describes a theoretical model of transition from executive activity to management using teaching activity as an example. This transition is explained in terms of management process of meaning¬making that has its own stages and is generally aimed at the formation of psychological readiness for the transition to management.
Motivation in Teenage Users of Social Media
Authors: Fyodorov V.V. , Mileev I.D.
Published: September 2015

The paper describes outcomes of a research on motivation in teenage users of virtual communicative spaces, that is, social networking sites. The hypothesis was that there is a correlation between teenagers' online activity in social media and features of their motivation. As it was revealed, types of teenagers' activities in social networking sites and types of motivation follow a certain hierarchy. Also, there are significant differences in motivations and time perspective in teenagers with different characteristics of online activity. The paper shows how these visible differences may be used in creating psychological motivational portraits of adolescents carrying out various activities in social media.
The Problem of Dialogical Personality in the Context of Modern Psychotechnology
Authors: Zhelyabin A.V.
Published: September 2015

The paper focuses on variations in understanding of personality in psychology and on the absence of the very category of personality in the modern Russian psychological practice. It aims to clarify the category of personality in the context of modern psychotechnical approach taking into account the key criteria of psychotechnicity, for instance, dialogicality. An assumption about the general pattern of overcoming all critical situations, including those of impossibility of emotional experience, is reviewed. The paper also outlines the key characteristics of personality and stresses the importance of working with personality — and, therefore, the need to acquire proper representations about this category. It explores the issue of the genesis of personality in cultural-historical psychology and associated fields and defines the general mechanism of development through interiorization. With several basic concepts of personality as examples, the paper concludes that personality can hardly thought of as something that exists within an isolated individual. Thus are introduces the notions of 'cumulative subject', 'step of personality development' and 'angle of meaning deflection'.
A Pragmatic Approach To Understanding Liquid Loading in Gas Wells
Authors: Riza M. F. , Hasan A. R. , Kabir C. S.
Published: September 2015

Liquid loading is the inability of a producing gas well to remove its coproduced liquids from the wellbore. The liquid flowing as droplets or film accumulates at the well bottom, thereby imposing backpressure at the sandface and triggering increasingly higher pressure loss in the wellbore. The problem initiated by liquid loading is manifested in terms of loss in well deliverability, causing the wellhead pressure to decline significantly, which, in turn, leads to the cessation of gas production. Accordingly, the liquid-loading issue reduces the ultimate recovery of a gas well.

Both the droplet-flow reversal and liquid-film-flow reversal have been postulated to be the underlying mechanism for liquid loading. Both mechanisms are predominantly premised on diagnosing the problem at the wellhead-flow conditions. This study explores the deliquefication issue in a gas well by fluid- and heat-flow modeling of the entire wellbore for a variety of flow situations in gas and gas/condensate reservoirs.

We observed that when a well experiences annular two-phase flow throughout the wellbore, no liquid loading occurs. The transition from annular flow to churn or slug flow initiates the liquid-film-flow or droplet-flow reversal, thereby triggering liquid loading. Most often, the flow condition at the well bottom controls the onset of liquid loading. By use of three published data sets, we show that the understanding of liquid loading improves when the entire wellbore-flow modeling is used. Forward modeling suggests that the tubing inside diameter and the well productivity index are the most important independent variables in determining the critical liquid-loading rate and the onset of liquid loading.
Road to Success and Lessons Learned in Intelligent Completion Installations at the Santos Basin Pre-salt Cluster
Authors: Schnitzler E. , Silva Filho D. A. , Marques F. H. , Delbim F. K. , Vello K. L. , Goncalez L. F. , Fonseca T. C.
Published: September 2015

This paper presents information regarding the installation of Intelligent Well Completions in Lula and Sapinhoá fields, at the Santos Basin Pre-salt Cluster. The technology is intended to improve reservoir management capability by using remote operated flow control valves and real time pressure and temperature monitoring for each perforated interval, which corresponds to different reservoir zones.

The benefits are obtained at the expense of additional challenges for well engineering, since well completion design becomes more complex and overall associated risks increase. Detailed and integrated planning is essential for the success of the operations, starting at the earliest phases of the well design and continued through detailed execution plans. The project team considered integration between downhole, subsea and topside systems as one of the main concerns during different planning phases.

First intelligent completion installations have been successful in pre-salt area, with no compromise to projects timeline or to the system performance. Applying the best practices learned during initial installations has been a key factor to achieve even better results in the following wells. Approximately 25 wells have been equipped with intelligent completions in Santos basin pre-salt area. Significant increase in performance and implementation time has been observed as a considerable amount of improvements have been made on system design and installations procedures.
Mechanistic Prediction of Oil-Water, Two-Phase Flow in Horizontal or Near-Horizontal Pipes for a Wide Range of Oil Viscosities
Authors: Li Liwei , Popa Florentina , Houchens Brent C.
Published: September 2015

The prediction of flow patterns transition is performed for oil-water, two-phase flows over a wide range of oil viscosities. Theoretical models of oil-water systems are studied in horizontal and near-horizontal pipe flows. The equilibrium flow pattern is dependent on the oil and water properties, pipe parameters, and flow rates. Four flow patterns are considered in the mechanistic model, including stratified (ST), core-annular (CA), oil-in-water (O/W), and water-in-oil dispersions (W/O). A mechanistic criterion, proposed by Zhang and Sarica (2006) for the same purpose, is used to identify stratified flow. The Brinkman (1952) model is used to distinguish the phase inversion of oil-in-water from water-in-oil emulsions. Boundaries of core-annular flow are based on the critical core diameter given by Brauner (2003). Comparisons between the mechanistic model predictions and published experimental measurements show good agreement in regime identification.

The importance of regime identification for correct pressure drop predictions is demonstrated by comparing the mechanistic model with a simple mixture model. The values of pressure drop predicted by both models are calculated and compared to existing experimental data. The mechanistic model shows significant improvement in pressure drop predictions.

Dimensionless groups from Buckingham Pi theory are used to investigate the sensitivity to the input parameters. The use of dimensionless groups reduces the number of dependencies from nine input parameters to six dimensionless groups. This reduces the complexity in the optimum design of pipeline systems. From most to least sensitive, for ranges typical of pipeline flow and fluids, the pressure drop prediction depends on the superficial Reynolds number of oil, Eotvos number, pipe inclination angle, superficial velocity ratio, density ratio, and viscosity ratio.
Probabilistic Bullheading Analysis is a Unique Risk Assessment Tool for Drilling and Completion Equipment Selection for Critical HP/HT Wells
Authors: Haghshenas A. , Cuthbert A. J.
Published: September 2015

This paper discusses the development and validation of the application of probabilistic bullheading analysis. Bullheading is the process of pumping fluid from the surface to the bottom of the wellbore in an attempt to deliver suitably weighted fluid to force fluid or gas from a given formation back into the formation. The methodology and procedure described in this paper provide a quantitative basis for risk analysis and equipment selection for high-profile wells, with focus on high-pressure/high-temperature (HP/HT) subsea well developments. As a result of this methodology, an accurate and risk-based approach can be taken using a probabilistic distribution of risks and pressure involved during bullheading operations.

The probabilistic model for performing bullheading analysis is based on the Monte Carlo method using statistical distribution of the parameters, which include reservoir properties, reservoir fluid properties, wellbore structure, and bullheading fluid properties. Each bullheading simulation assumes the wellbore is filled with the formation fluid and determines the shut-in pressure. Then, bullheading simulation considers the changes in pressure-volume-temperature (PVT) properties, fluid loss into the formation, fracture initiation, and compressibility of the fluids. Each probabilistic simulation run performs 2,000 simulations. The shut-in pressure and maximum pumping pressures are recorded to provide probabilistic distributions for risk-based analysis.

The application of the methodology is demonstrated using an example case study. A special emphasis is placed on performing a quality check of the statistical data to mitigate any skewedness that might occur during the simulations. A total of 24,000 simulations were performed to provide the distribution of pressure during the bullheading operation. The results can be presented in a variety of plots, including maximum bullheading pressures, maximum shut-in pressures, probability of fracturing, and the effect of pressure depletion.
Material Supply Challenges in the Offshore Project Environment
Authors: Kendig Bryan
Published: September 2015

This paper highlights challenges to material supply delivery schedules confronting the offshore major project sector. Topics are addressed to illustrate challenges with respect to: specification of equipment (clarity and timing), defining equipment packages, vendor risk assessment, quality control within the supply chain, and identifying the right personnel and workload planning for managing equipment fabrication. Experience-based recommendations are provided in order that organizations may mitigate these challenges on future major projects. The examples provided are based on the FPSO industry, but the challenges and the recommendations equally apply to other offshore structures, including Spars, TLPs, and semi-submersible platforms.
Method to Create Multiple Collocated Hydraulic Fractures Using a Temporary Localized Change in Stress Anisotropy Produced During an Initial Stimulation Treatment
Authors: Lewis Bryan J. , Surjaatmadja Jim B.
Published: September 2015

During a hydraulic fracturing stimulation treatment, transient geomechanics forces are exerted on the formation which modify the stress landscape near the wellbore and fracture planes. In regions where the horizontal stress anisotropy is less than 25%, there is a possibility for a temporary reversal in the minimum stress direction. During this brief window, a secondary hydraulic fracture can be created in a completely different direction, thus providing direct connectivity to previously unattainable locations in the formation.

This paper presents a computational validation of the multioriented hydraulic fracturing (MOHF) process. As traditional hydraulic fracture simulations are derived using static formation properties and steady-state assumptions of the formation behavior, a unique transient 3D computational geomechanic fracture simulator was developed to perform this study. The new model incorporates cohesive zone elements to represent the fracture plane, and captures the dynamics of the fracture initiation and propagation, as well as the transient stress modification in the formation. A realistic 3D fracture transient behavior is accounted for by the inclusion of multiple rock layers in the model, which are connected through energy absorbing frictional elements.

The simulations provide time sensitive operational recommendations for performing the MOHF stimulation to achieve maximum production increase from the well. Time lapse stress fields show vivid windows of opportunity where new fractures can be influenced to extend in alternate directions, hence offering formation drainage not attainable using conventional stimulation approaches. Production levels of twice to five times were predicted using reliable production simulators.

This new stimulation method enhances the state-of-the-art in hydraulic fracturing by requiring an understanding of the transient geomechanic response in the treatment area. As a time dependent method, this approach opens a new window of opportunity—both in conventional and unconventional plays—by providing connectivity to previously unattainable locations in the formation. Unfortunately, it also brings new complications. Industry standard fracture simulation technology becomes incomplete, as most models neglect the transient response of the system. Additionally, the availability of data related to the dynamic behavior of rocks is limited. The dynamic compression of the rock, slip characteristics between rock layers, and the amount of energy stored within slip planes—all recorded as a function of time—are particularly important when considering an MOHF process. Additional testing must be performed to obtain these data.
Completion Optimization Provides Step Changes in Horizontal Well Performance in the Nuiqsut Formation – An Oooguruk Field (Alaska) Case History
Authors: Bond Andy , Jasser Rami , Johnson Vern , Morgan Mike , Martin Mike , Palisch Terry , Williams Brock
Published: September 2015

The Oooguruk Unit is located on a man-made gravel island in the Beaufort Sea, five miles offshore the Alaskan North Slope in Harrison Bay. The field produces from the Kuparuk, Torok and Nuiqsut reservoirs. The focus of this paper is the Nuiqsut sandstone which is currently undergoing water and lean gas injection for secondary recovery. The wells are completed as 6,000 ft to 7,000 ft horizontal laterals aligned parallel with the preferred fracture orientation in a line drive waterflood pattern. Recent optimizations in mechanical diversion fracturing in these laterals have provided significant improvements in production rates including several recent wells with initial production of over 7,000 BOPD. This paper will document the completion and fracturing design evolution over several vintages of wells, as well as the use of pre-installed tracer systems to verify production uniformity and diversion success.

The reservoir ranges in thickness from 60 ft to 120 ft and is divided into several producing sand and shale intervals. The initial completion type planned for this reservoir was an 8,000 ft long undulating open hole horizontal lateral. This was quickly abandoned after the first well collapsed in a shale section. Undulated wellbores continued to be drilled for producing wells but were completed with pre-perforated pups spaced evenly throughout the liner in the horizontal section. These wells were stimulated with dynamic diversion fracturing treatments. Because of the logistical difficulties and expense in fracturing operations on a gravel island in the Beaufort Sea, two wells were also completed as multi-laterals, but resulted in productivity similar to dynamic diversion fracturing in one well and significantly less in the second well.

The initial move to undulated horizontal wellbores utilizing dynamic diversion fracturing treatments resulted in production improvements of nearly 100% over unstimulated wells. This led to the use of mechanical diversion techniques implemented in relatively flat horizontal laterals. This completion-type allowed mechanical diversion fracturing treatments utilizing over three times the low density ceramic proppant and generated wells with initial production of over 7,000 BOPD (an additional 100% increase over dynamic diversion fracturing). All future producing wells are now planned to be completed with mechanical diversion equipment. The completion optimization evolution described in this paper will be useful to completion and development engineers of other conventional reservoirs, and the learnings are already being successfully applied to another nearby Alaskan North Slope development.
Key Engineering Highlights of Facilities and Equipment for Oil & Gas Production
Authors: Mirza Babar , Al-Kharqawi Fahad
Published: September 2015

The paper provides an insight into key engineering aspects of Kuwait Oil Company's existing projects, facilities and equipment both current and from nearly 30 years of projects development. It deals with engineering features of mainly process and mechanical equipment, both static and rotating besides others, used for collection, separation, desalting, heat transfer, chemical treatment, storage, transmission, pipelines and similar facilities utilized for upstream oil and gas production, both sweet and sour. Engineering highlights include certain technological developments, metallurgical aspects, few best practices and lessons learnt as well. Seven (7) case studies are included towards the end that show case some of the engineering aspects of facility equipment, lessons learned from their engineering and conclusions drawn that emphasise the need to focus on initial, preliminary engineering aspects of projects and could provide useful tips for oil and gas engineers and designers.
Formulation of a Transient Multi-Phase Thermal Compositional Wellbore Model and its Coupling with a Thermal Compositional Reservoir Simulator
Authors: Forouzanfar Fahim , Pires Adolfo P. , Reynolds Albert C.
Published: September 2015

In this paper, we develop the detailed formulation of a transient multi-phase thermal compositional wellbore model and couple it with a thermal compositional reservoir simulator. We consider the presence of at most three phases which are an aqueous phase (water with dissolved CO2), a hydrocarbon liquid phase and a hydrocarbon vapor phase. The volume of wellbore is divided into a set of 1-D control volume grids. The mass balance equations for all components and the total energy balance equation are discretized over the wellbore control volumes. The transient total momentum balance equation (along the wellbore) and the drift-flux model equations for gas-liquid and oil-water systems are discretized over a set of backward staggered grids with respect to the wellbore grids. Following the assumption that the hydrocarbon phases inside a wellbore control volume are in equilibrium, a set of constraint equations are introduced to enforce the equality of the fugacity of each component in both hydrocarbon phases. The solution algorithm for the wellbore model is similar to the one for a compositional reservoir simulator, where, the sets of simulation equations and unknowns are divided into the sets of primary and secondary equations and unknowns which are solved sequentially. The appearance and disappearance of the hydrocarbon phases follow the phase stability and two-phase flash calculations. The wellbore model is fully coupled with a reservoir simulator at the bottom of the well. The interaction of wellbore with reservoir is handled with definition of source terms in the mass and energy balance equations and is obtained from continuity of force, energy and mass fluxes across the reservoir/wellbore interface. The boundary conditions for the wellbore model depend on the well control which includes the specified pressure or production rate at wellhead. Within the computational results section, the validation of the wellbore model against the analytical solution for the shock tube problem is presented. Moreover, the coupled wellbore/reservoir simulator is used to model the drawdown and buildup tests of a well in a single-layer reservoir, and a relatively long period of production from a multi-layer volatile oil reservoir.
Review and Analysis of Zonal Isolation Effectiveness in Carbonate Reservoirs Using Multi-Stage Stimulation Systems
Authors: Nozaki M. , Burton R. C. , Furui K. , Zwarich N. R.
Published: September 2015

It is common practice to complete long carbonate intervals with multi-stage stimulation treatments especially in horizontal wells. Each zone tends to be mechanically isolated using cement or openhole packers and then acid stimulated. Zonal isolation effectiveness is judged on the basis of job pressure response or post-job production logging. The recent introduction of intelligent well systems (IWS) with zone specific pressure and temperature gauges allows more effective review of zonal isolation during stimulation.

This paper reviews zonal isolation results from a series of high-rate acid jobs conducted in wells equipped with zone-specific pressure and temperature gauges. 21 acid stimulation jobs from 13 different wells are reviewed to investigate the effectiveness of zonal isolation during and after treatment. Well examples presented in this paper cover several different completion types: cemented and un-cemented; intelligent well system, plug-and-perf completion and ball-activated sliding sleeve completion. The analysis revealed several different pressure and/or flow communication patterns. Field examples and analysis results presented in this work will help engineers design and optimize cemented and un-cemented wells requiring multi-stage stimulation in carbonate fields.
Optimized Fracture Stage and Perforation Placement in Horizontal Wells using a New Calibrated Pulsed-Neutron Log Workflow
Authors: Dahl Jeff , Samaripa James , Spaid John , Hutto Erek , Buller Dan , Johnson Bill , Mcilroy Chris
Published: September 2015

Evidence continues to mount to indicate that the geometric placement of fracture stages and perforation clusters in horizontal wells results in variable well production, with many clusters contributing little or no production. Any engineered completion design should require stages to be segregated by similar petrophysical and mechanical properties. The authors propose to reduce the cost per barrel of oil equivalent (BOE) and to improve estimated ultimate recovery (EUR) by using a novel log-derived completion method to better select perforation clusters and stage location to provide better fracture placement.

A low-risk, pumped down, cased-hole pulsed-neutron log (PNL) is used after the well is cemented before completion. Using readily available geosteering software, the geologic projection of vertical well log measurements and the interpreted formation properties along the horizontal well enable a rigorous calibration method for PNL interpretation. Inelastic pseudodensity, neutron porosity, and resistivity-sigma calibrations can then generate a cased-hole triple combo. Elemental yields for silica, calcite, and potassium are used with additional clay inputs for a basic mineralogy interpretation. These inputs, within a specialized workflow, calculate a “production index” and “frac index” used to generate custom staging designs.

Experience in a major unconventional play has shown a dramatic reduction in the number of stages and the completion cost per well. In addition, data from producing wells, using a software-derived stimulation design, has been matched to geometrically staged wells in the area. The addition of PNL data to interpret the position of the lateral well has been observed to reduce uncertainty when compared to the logging while drilling (LWD) gamma ray (GR) alone. The completion results for stages also provide good evidence that the overall efficacy of the stimulation treatment was increased by the perforation placement. The conclusions from this work show substantial completions cost savings per well while maintaining overall EUR in a difficult unconventional shale play. Based on pressure observations during stimulation, it is believed that stimulation efficiency has been increased. Using fewer stages to target the more productive rock and perforation clusters to target the sweet spots for stimulation has provided a substantial cost/BOE reduction.

Although the technology for using a PNL log in the horizontal well has been attempted previously, there was not the benefit of a rigorous calibration method. The geologic projection of vertical wells is a novel approach to calibrate thousands of feet of logged PNL data. In addition, the custom staging design uses a novel, unbiased approach to select the optimum stage and perforation placement to minimize completions cost while maximizing productivity.
Novel use of Electro Coalescence to Enhance, Optimize and Debottleneck Oil Separation Trains
Authors: Amarzguioui Morad , Jacobsen Per Christian
Published: September 2015

Many challenges are encountered when separating oil and water in onshore and offshore production trains. The challenges include presence of stable emulsions, increased water cuts, small water droplets due to high shear or pressure drops, and/or high crude viscosities. These issues can have a significant negative impact on the separation efficiency if not addressed properly. The conventional way of addressing these issues usually involves a combination of high process temperatures, high chemical dosages, large vessels and/or increased number of separation stages. Conventional solutions often demand increased energy consumption, higher material costs, larger operating costs, more weight and/or larger space requirement for the production facility. Furthermore, conventional solutions are not always practically feasible, due to restricted energy availability or space restrictions.

Early stage implementation of electrocoalescence through VIEC (Vessel Internal Electrostatic Coalescer) technology allows for a much more efficient and cost effective means of resolving the challenges in the separation train. The VIEC technology was the OTC “Spotlight on new Technology” award winner in 2004 and has since then been implemented in several major projects.

The VIEC technology applies high voltage electrical fields to promote droplet-droplet coalesce, thus greatly speeding up and enhancing separation efficiency. VIEC technology combines fully insulated electrodes with a low voltage feed and distribution inside the separator shell. Due to these characteristic features, the VIEC technology can tolerate any water cut and presence of gas, as opposed to conventional electrocoalescers. Consequently, the technology enables use of the powerful mechanism of electrocoalescence in any three-phase separator to speed up separation efficiency and resolve emulsion problems.

VIEC Technology will reduce the BS&W out of a given separator, increase capacity of an existing separator or enable a more compact separation solution for a given throughput of crude. Additional benefits include production at higher viscosities and at lower temperatures and improved level control due to reduced emulsions layers. Furthermore, consumption of demulsifier is often seen to be reduce significantly, when electrocoalescence is applied compared to conventional separation.

The paper will give a detailed presentation of the mechanism of electrocoalescence and how it is implemented in the VIEC technology. The paper will focus on how to predict electrostatically enhanced separation performance by combining laboratory testing with separation modelling, to give representative predictions of separation benefits and allow for designing solutions custom-fitted to specific separation challenges. A specific case from the Gulf of Mexico will be presented, where an existing TLP was retrofitted with VIEC technology to increase its capacity and enable a tie back from a nearby reservoir.
Modelling with Multidimensional Matrices for Project Economics, Portfolio and Business Plan Generation and Analysis
Authors: Tahirov Tahir
Published: September 2015

The live example of modelling and application of interrelated, multidimensional, expandable matrices in E&P (Exploration & Production) business is presented. Efficiency achieved in terms of using multidimensional, linked structure, formulas shared across dimensions is demonstrated. Overall process of easy model construction and modification which saves time and provides opportunity for insightful, value-added analysis for petroleum investment decision-making is explained.

The new approach realised by using matrices based software solution. Dimensions of E&P projects - price scenario, participation, time, etc. shared across matrices of cash flow, profit and loss, work program, economics. Possibility of adding new project (or its version) as a new dimension is realised. In the Project economics module assumption and calculation matrices are separated, hierarchy of assumptions – global (centrally controlled via database link) – country - project is established. Formulas with meaningful mnemonics are placed outside of cells. One easily examined formula shared across dimensions which allows significant reduction of size and enhances transparency of models. Project data flows to database using JDBC (Java database connectivity) and this database used to generate the E&P portfolio module for project selection, ranking, impact analysis and visualisation. For the selected portfolio of projects (country, region, global) in the Business plan module capital investments, cash flow, P&L as well as work program and production reports are generated.

Working economics-portfolio-business plan system serves to address the modern E&P company challenges such as project valuation, risks associated with project (volume, delays, cost increase, etc.), optimal acquisition or divestiture terms, as well as portfolio analysis, resource constrains, project prioritization. The system enables to quickly conduct what-if analysis testing various contractual terms, price scenarios, investment size and schedules, production profiles. Fully customizable and flexible matrix system allows modelling non-standard projects with production sharing agreements, complex acquisition or divestiture terms, gas-to-power option, and specific fiscal terms.

The developed system allows oil and gas companies to get better business insight, save modelling and planning time and go beyond error-prone spreadsheets. Particularly small to medium companies can benefit having solution that address inherent limitations of spreadsheets but at the same time does not require investment in the costly enterprise systems.
New Foam Drilling Hydraulics Calculations by Using Two Foam Flow Regimes
Authors: Edrisi Ali Reza , Kam Seung Ihl
Published: September 2015

In spite of its complexities, foam underbalanced drilling has unique advantages such as reduced formation damage, improved rate of penetration, higher cutting-transport capacity, and lower circulation losses. Recent experimental studies in a wide range of experimental conditions show that foam flow in pipe can be represented by two different flow regimes: (i) the low-quality regime showing stable plug-flow pattern with fine-textured foams and (ii) the high-quality regime showing unstable slug-flow pattern with alternating free-gas with fine-textured foam segments. Such a new concept was successfully captured by a foam modeling technique with five model parameters, reproducing two distinct pressure contours.

This study, for the first time, constructs foam drilling hydraulics model with two foam-flow regimes handling both stable and unstable flow characteristics, and investigates how the model improves current foam drilling hydraulics modeling based only on stable foam flow behavior. The results from three different scenarios (scenario 1: a vertical well, scenario 2: a deviated well with relatively short horizontal section, and scenario 3: a deviated well with relatively long horizontal section) with the transition foam quality between the two flow regimes (fg*) around 75-85% showed that significant differences in drilling hydraulics calculations might occur when the conventional technique was replaced by this new technique. For example, a drilling scenario tested with 10,000 ft deep vertical well (scenario 1) was shown to have as much as 32%, 48%, and 25% deviations in foam density, total velocity, and pressure gradient, respectively, at the bottomhole. Examples from two other deviated well trajectories (scenario 2 and scenario 3) exhibited similar responses, showing even more deviations. These results clearly demonstrate why incorporating two foam flow regimes into the current drilling hydraulics calculations is a crucial step toward evaluating and designing foam drilling practice accurately and reliably.
Rheological Hierarchy Optimization Improves Fluid Displacement and Well Integrity, 3 Worldwide Case Studies
Authors: Shadravan Arash , Alegria Adriana , Castanedo Rodrigo
Published: September 2015

A good cement job is the Achilles' heel of sustainable production from oil and gas wells. Improving zonal isolation and the integrity of wells worldwide is the priority of well integrity engineers. Proper cement designs and job execution assure sustainable production with ideal zonal isolation. The US unconventional horizontal well drilling has been increasing over the recent years. There are several solutions and best practices including maintaining the rheological and friction pressure hierarchy of the fluids pumped. Spacer rheological properties modeling computer simulations lead to a smart spacer design and, if correctly executed, yield enhanced fluids displacement efficiency and well integrity. The objective of this paper is to demonstrate the benefits of rheological hierarchy optimization and explain the benefits of the execution of this concept in three case studies worldwide. A predictive rheological model was developed for a micro-emulsion weighted spacer technology which was pumped in these cases.

In the horizontal section of a well and during fluid displacement, density hierarchy would not prevent fluid intermixing and viscous fingering hence to improve the fluid displacement efficiency a rheological hierarchy optimization is essential. This study showcases how by engineering the rheological properties of a spacer fluid the friction pressure Hierarchy in the horizontal section (liner and long strings casings) was designed. Adjusting the proper spacer's viscosifier and surfactant and being able to predict the rheological properties is another key to achieve zonal isolation. A sensitivity analysis was performred with the inhouse cement displacement simulators and fluid compatibility tests were completed in the laboratory. Results presented by the in-house simulators with three dimensional (3D) visualization and bond logs confirm how engineering, planning and optimizing the rheological and friction pressure hierarchy could achieve zonal isolation.
Mechanical Versus Mineralogical Brittleness Indices Across Various Shale Plays
Authors: Kias E. , Maharidge R. , Hurt R.
Published: September 2015

In hydraulic fracturing, it is natural to think that regions of brittle rock are prime candidates for effective fracture network creation or may be relatively easy to fracture. Consequently, various forms of brittleness indices have been introduced, in part, to decide where to place perforation clusters in multi-stage horizontal completions. These brittleness indices are often calculated using correlations between elastic parameters and mineralogical data, primarily because mineralogical information is readily obtained from wireline logs, cores, or cuttings. This presents two unresolved issues. First, while it is likely that a relationship between brittle failure and stiffness qualitatively exists, the efficacy of leveraging these indices in a quantitative manner remains uncertain. Second, there are limited examples comparing direct rock core measurements to indices calculated from mineralogical data, leaving room for ambiguity in what the magnitude of brittleness indices mean to hydraulic fracture initiation and propagation.

This study aims to clarify the definition of brittleness by comparing laboratory-derived rock mechanical properties, mineralogical and mechanical brittleness indices. Shales evaluated include the Floyd, Haynesville, Eagle Ford, and Barnett. Rock properties measured in this study are Young's modulus, Brinell hardness, tensile strength, and compressive strength. The mineralogical content of the specimens was determined by the x-ray diffraction (XRD) technique. A mineral-defined brittleness index is computed from the XRD data, while the mechanical brittleness indices are computed from tensile and compressive strength testing of core from these shale formations. Results show little agreement among the mechanically based indices, but hardness measurement trends coincide with elasticity-based mechanical indices and mineralogical indices. Additional data is needed verify the possible relationship between tensile strength and mineralogy. Strong correlation exists between mineralogical-based brittleness and Brinell hardness in the Eagle Ford and Haynesville shales. The Brinell hardness index could be applied in lieu of brittleness with the added benefit of estimating proppant embedment.
Insights of Wormhole Propagation During Carbonate Acidizing: Constant Pressure vs. Constant Rate
Authors: Gomaa Ahmed M. , Nino-Penaloza Andrea , Cutler Jennifer , Chaudhary Saleem
Published: September 2015

Acidizing of carbonate reservoirs is a common technique used to restore and enhance production by dissolving a small fraction of the rock to create highly conductive channels. Literature review reveals that most acidizing studies are focused on acid injection at a constant volumetric rate (CVR) instead of at a constant injection pressure (CIP). Therefore, the primary objective of the present work is to investigate the benefits and recommended applications of each technique. The study analyzes dissolution patterns, and wormhole propagation rate.

A coreflood study was conducted using different Indiana limestone cores to assess both techniques. Additionally, a 2-D wormhole model was used to mathematically describe the acidizing phenomena. This model describes the reactive transport of acid as a coupling between Darcy scale flows. The algorithm captures the essential physics and chemistry of the acid reaction in a carbonate porous medium.

The study confirmed that all types of acid dissolution patterns (i.e. face, conical, wormhole, and branched) exist for both techniques (CVR or CIP). Unlike in the CVR technique, dissolution patterns during the CIP technique can change, tending toward a branched dissolution regime. The CIP technique required a lower acid volume to achieve breakthrough in the conical dissolution regime and a higher acid volume to achieve breakthrough the branched dissolution regime compared to the CVR technique. In a dominant wormhole pattern, both techniques required nearly the same acid volume for breakthrough. A CT scan confirmed that the CIP technique develops a uniform wormhole at a low initial injection rate. For the CIP technique, the acid injection rate increased exponentially with the volume of the acid injected.