bluuebunny/crossref_metadata_2025_split huggingface dataset:
Restoration of Reservoir Cores to Reduced Reservoir Conditions for Chemical EOR Studies: Impact on Mineralogy, Pore Structure and Rock/Fluids Interactions.
Authors: Guillon Valentin , Kohler Eric , Wartenberg Nicolas , Rousseau David 
Published: March 2017

Abstract
Reservoir rock samples available for chemical EOR studies are often not preserved. It is well known that wettability has to be restored by appropriate protocols. Some authors showed that rock samples should also be restored with respect to redox mechanisms, in particular in view of EOR studies involving polymer and surfactants. This could mainly be achieved by using reducing fluids removing the iron oxides formed at the surface. Still, the impact of such reducing fluids on minerals and pore structure is unknown. In this paper, we analysed the impact of various reducing fluids on a complex Bandera brown sandstone outcrop containing minerals present in many sandstone reservoirs.
The sandstone mineralogical composition and petrophysical properties were at first fully characterized by classical core analysis, XRD and SEM measurements. This rock was found to contain high amount of clays such as kaolinite and chlorite, few feldspars, calcite cement and iron oxides. Reducing fluids were taken from literature and used to reduce rock surface to various extends. Impact on mineralogy, pore structure as well as on surfactants adsorption were evaluated by static and dynamic adsorption measurements and XRD/SEM analysis.
Main results have shown that rock mineralogy was impacted by reducing fluid, resulting in calcite cement dissolution. Depending on the presence or not of chelating agent, iron and calcite solubilized by the reducing fluid were sometimes shown to re-precipitate in the core (iron precipitating with sulphur under pyrrhotite form). Pore structure was hence strongly impacted by those dissolutions and precipitations.
A limited decrease of adsorption of surfactants was observed after reducing treatment. It is still unclear if this decrease is due to iron reduction or to calcite dissolution. Reducing fluids used were found to be unable to reduce rock surface while preserving pore structure and mineralogical composition of rock. It is then still unclear that reduced state has to be restored whereas it is clear that such fluids should not be used without studying their impact on mineralogy and pore structure.
An Enhanced Nonlinear Analytical Model for Unconventional Multifractured Systems
Authors: Molina Oscar , Zeidouni Mehdi 
Published: March 2017

Abstract
One of today's challenges in reservoir management of liquid-rich shales is to forecast production performance based on rate/pressure transient analysis. The need of large pressure gradients to produce from shale reservoirs through multifractured horizontal wells (MFHW) can induce considerable changes in rock and fluid properties that can largely affect the bottom-hole pressure behavior with time and consequently the accuracy in the prediction of well performance. Therefore, the assumption of constant properties in shale reservoirs may not be safe when modeling MFHWs performance. This paper presents an analytical model for MFHW that accounts for pressure-dependent rock and fluid properties by the application of a modified pressure to the five-region model (Stalgorova and Mattar, 2013) which can be easily inverted to get an analytical solution to the nonlinear problem in terms of pressure. The validity of the proposed MFHW performance model is compared against data obtained from numerical simulation for several case studies. We observe that our analytical solution accurately captures bottom-hole pressure behavior and gives an excellent estimation of depletion time under a certain restriction. Furthermore, we find that nonlinear diffusion processes in liquid-rich shales, for which pressure-dependent rock and fluid properties are given in exponential form, can be fully described by using the Porous Medium Equation (PME). We present a straightforward application of the PME to predict flow regimes (fast diffusion, normal diffusion or slow diffusion) and the excess energy gained or required to keep a constant production rate in MFHW undergoing nonlinear diffusion; however, the application of the PME to the five-region model is not forthright and remains a matter of future development.
Next-Generation Supramolecular Assemblies as Displacement Fluids in EOR
Authors: Yegin Cengiz , Jia Bao , Zhang Ming , Suhag Anuj , Ranjith Rahul , Balaji Karthik , Peksaglam Zumra , Thanon Diyar , Putra Dike , Wijaya Zein , Saracoglu Onder , Temizel Cenk 
Published: March 2017

Abstract
Current analyses indicate that 50% of oil produced in USA and the world will be through EOR technologies in the next 20-25 years, and heuristics suggest that polymer flooding should be applied in reservoirs with oil viscosities between 10 and 150 mPa.s. The key factor limiting the recommended range is that for oil viscosities greater than 150 mPa.s, where injected water viscosity values required for a favorable mobility ratio give rise to prohibitively low values of polymer injectivity and pumping efficiencies. Herein, we propose that a novel type of supramolecular system based on the complexation of long chain amino amides and maleic acid with reversibly adjustable viscosities can enable us to overcome the injectivity limitation.
The concept is that viscosity of the injected supramolecular system will be maintained initially at low values for easy injection and pumping, and then increased by means of an external pH stimulus just before or upon contacting oil. Our promising lab-scale preliminary studies have indicated that such supramolecular systems possess not only reversible pH-responsive properties, but are also very tolerant to high salinities and temperatures.
While polymers degrade and break up upon experiencing sudden extreme shear stresses and temperatures, supramolecular solutions merely disassemble and re-assemble. Therefore, supramolecular solutions can be considered as healable polymer solutions in a way. Supramolecular solutions can adapt to the confining environment. For instance, when a high molecular weight polymer macromolecule is forced to flow into narrow channels and pores, molecular scission processes may take place.
Supramolecular solutions can have a significant impact in the cases where thermal methods cannot be used for some viscous oils due to thin zones, permafrost conditions and environmental constraints. This project is primarily aimed at developing novel supramolecular assemblies with adjustable viscosity and interfacial properties that have robust tolerance against high temperatures and salinities. Such supramolecular assemblies will be used to significantly improve the feasibility and cost-effectiveness of displacement fluids used in EOR. Overall, there is a significant potential for application of supramolecular solutions in the US and throughout the world.
Step Rate Test as a Way to Understand Well Performance in Fractured Carbonates
Authors: Shchipanov A. , Kollbotn L. , Prosvirnov M. 
Published: March 2017

Abstract
Step Rate Test (SRT) is commonly used to estimate formation parting (or fracture opening) pressure for stimulated wells. SRTs may also focus on changes of well performance at different rates / pressures that is of special interest for stress-sensitive reservoirs such as fractured carbonates. Installation of permanent downhole gauges (PDG) and running SRTs on injection wells at the Ekofisk field gave a chance to improve the understanding of reservoir and well performance. Analysis of these SRTs also resulted in further development of SRT interpretation techniques.
An approach to SRT interpretation, combining analytical pressure-rate (p-Q) curve analysis and step-by-step Pressure Transient Analysis (PTA) with numerical simulation of SRT, was suggested and tested. Applying this approach to Ekofisk SRTs has shown that the p-Q analysis may be used for diagnostics of well performance changes, while step-by-step PTA enables decomposing of well (skin factor) and reservoir (conductivity) effects with estimation of corresponding well-reservoir parameters as pressure or rate functions. Numerical simulation confirmed that pressure dependent conductivity estimated from the step-by-step PTA is the governing factor in matching SRT history.
Special attention was paid to the uniqueness of SRT interpretation using suggested approach. Reaching infinite acting radial flow (IARF) regime at each step of a test provided unique parameter estimates as shown by example of a stimulated slanted injector. Being too far from IARF at end of each step will make the interpretations more uncertain. Different sets of changing parameters estimated from SRT interpretation could provide satisfactory match in numerical runs as was illustrated by example of a horizontal injector with multiple induced fractures. Comparison of interpretation results for different wells integrating additional field data is a possible way to reduce this uncertainty.
Finally, some hints to designing, conducting and interpreting SRTs of different types of wells in fractured carbonate fields are given, using Ekofisk field experience.
Capillary Pressure in Nanopores: Deviation from Young-Laplace Equation
Authors: Li Bo , Bui Khoa , Akkutlu I. Yucel 
Published: March 2017

Abstract
Recent studies on multi-phase fluids in nanoscale capillaries indicated that the capillary wall-fluid interactions could play a dominant role on the co-existence of the phases, which may change the fundamental properties of the fluids, such as density, viscosity, and interfacial tension. At the extreme of the confinement, these properties become vague. This raises a serious question on the validity of Young-Laplace equation to predict capillary pressure in small capillaries that the unconventional resources commonly exhibit. In this paper, using nonequilibrium molecular dynamics simulation of mercury injection into model nanocapillaries, the nature of multi-phase fluids is investigated in capillaries with sizes below 20nm, and the Young-Laplace equation is re-visited.
Higher capillary pressure is predicted for the model nanocapillaries used in the simulations compared to that value obtained using the Young-Laplace equation, in particular, when the capillary diameter is less than 10nm. Good agreement found with the theory in larger size capillary. The capillary pressure increases as the capillary size is decreased and shows a power-law dependence onthe size of the capillary. This dependence yields up to 70% increase in the estimated capillary pressure value for the extreme case of 1nm capillary. Higher tangential local pressures at the nanocapillary entry resulted from the adsorption phase is the cause of the difference.
Based on the observations, a modified Young-Laplace equation is proposed for mercury-airfilled pore systems which are commonly used in Mercury Injection Capillary Pressure (MICP) experiments for the pore volume and pore size distribution measurements. At the highest injection pressure of MICP, the minimum captured size is predicted 4.8nm instead of 3.6nm based on the Young-Laplace equation. The increase in the predicted capillary size leads to an increase in total pore volume of the sample. The error in volume is up to 20% for measurements with shale samples. The results are important for the characterization of resource shale formations because the nanopore volume correction influence the hydrocarbon in-place and reserve calculations.
The work can be extended to other multi-phase systems, such as oil-water, and water-gas, grouping with other capillary wall material to study the behavior of multi-phase flow in nanocapillaries.
Development of a Parallel Simulator Utilizing Multiple Interacting Continua and Embedded Discrete Fracture Models in Fractured Unconventional Reservoirs
Authors: Wang Kun , Liu Hui , Luo Jia , Chen Zhangxin 
Published: March 2017

Abstract
Unconventional petroleum reservoirs, such as shale gas and tight oil reservoirs, have changed the entire energy equation in the world. An accurate and efficient reservoir simulator is essential for the development and management of these reservoirs and the optimization of their production schedules. However, the gas storage and transport mechanisms in ultra-tight matrix, including gas adsorption/desorption, non-Darcy flow, and surface diffusion, are different from those in conventional petroleum reservoirs. In addition, hydraulic fracturing techniques are often required to achieve their economical production, which leads to existence of complex fracture networks in the unconventional reservoirs. These features of unconventional reservoirs make their accurate numerical simulations a big challenge. In this paper, we develop a simulator for fractured unconventional reservoirs, which takes the specific gas storage and transport mechanisms into consideration, employs a multiple interacting continua (MINC) model to handle well connected natural fractures, utilizes an embedded discrete fracture model to simulate large-scale disconnected hydraulic fractures, and uses a coupled model to efficiently describe multi-scale fractures with irregular geometries. To reduce the computational time, parallel computing techniques are also employed, with which large-scale reservoir simulation cases can be finished in practical time. From the numerical experiments, we can see that reasonable physical phenomena is captured and accurate predictions are performed by this simulator.
Shale Gas Well Total Fracture Surface Area Calculation Re-Visited for a Dynamic Formation Permeability
Authors: Soni Laura Pelaez , Akkutlu I. Yucel , Maggard J. Bryan 
Published: March 2017

Abstract
Shale gas wells exhibit formation linear flow, which is in most cases the only transient flow regime available for engineering analysis. Production Rate Transient Analysis (RTA) methods have been developed to analyze the transient flow into shale gas well. These methods often assume homogeneous reservoir properties and neglect the dynamic nature of the formation. In shale gas reservoirs, however, the properties could change; in particular, the permeability due to stress-dependence of the formation and non-Darcian effects. In this work, a theoretical study is conducted to show the range of errors on the predicted total fracture surface area caused by the constant permeability assumption. The study proposes a modified RTA model, which accounts for dynamic permeability to eliminate the error in calculated area.
Results from the sensitivity analysis show that the error on surface area calculation ranges from 1% – 323% due to the constant permeability assumption. The total fracture surface area calculation is most sensitive to the geomechanical (stress-sensitive) parameters, which affect the permeability in the region away from fractures. Results show that the error in area is reduced when the initial value of the dynamic permeability is large. Sorption parameters are the second most influential category affecting the surface area calculation. Molecular diffusion of the adsorbed and free gas molecules enhance permeability near the fractures, wherein the slightest variations in dynamic permeability can cause the error in area to change significantly. For these parameters, higher permeability near the fractures translates to higher error in area.
Seismic History Matching Using a Fast-Track Simulator to Seismic Proxy
Authors: Geng Chong , MacBeth Colin , Chassagne Romain 
Published: March 2017

Abstract
In this paper we propose a proxy model based seismic history matching (SHM), and apply it to time-lapse (4D) seismic data from a Norwegian Sea field. A stable proxy model is developed for generating 4D seismic attributes by using only the original baseline seismic data and dynamic pressure and saturation predictions from reservoir flow simulation. This method (MacBeth et al., 2016) circumvents the petro-elastic modelling with its associated uncertainties and also the need to choose a seismic full-wave or convolutional modelling solution, which are used in conventional simulator to seismic (sim2seis) modelling. The method is tested on an offshore field case study from the Norwegian Sea.
In this study we firstly perform a check on the validity and accuracy of the proxy approach following the methodology of (Falahat et al. 2013) as a guide. The results confirm linear superposition between the pressure and saturation effects controlling the seismic data. Next a quasi-history matching is set up - here simulation model realisations are selected by random assignation of the key parameters to define a walk through solution space. After this, both the sim2seis and proxy modelling approach are compared for each realisation against a known reference case. The results show a mean seismic error of lower than 5%, which indicates the possibility to utilise a fixed proxy to model the 4D seismic. Finally, the full seismic history matching loop is implemented, where the sim2seis and the proxy-driven SHM are launched to find the optimal solution for our field. A particle swarm optimization (PSO) algorithm is applied as the optimisation tool, and only seismic data are used in the objective function. In both cases the algorithm converged after 30 iterations, and the optimal solutions of the two schemes are comparable. It is observed that the full sim2seis and proxy-driven SHMs are only marginally different, implying that solution space is similar in both cases. We also observe that in either case, matching to seismic data only can improve the production match. A unique feature of this study is the application of a seismic modelling proxy in the SHM scheme. Despite its relative simplicity, the approach is found not to bias the optimal solution of the more conventional SHM where the full physics of seismic modelling is applied. Meanwhile, this approach can save over 60% of the total computing time compared with the normal procedure, and this helps significantly to achieve a rapid and effective seismic history matching and better define uncertainty with a larger number of realisations.
Conformance Control Using SMG Microgels: Laboratory Evaluation and First Field Results
Authors: Zaitoun Alain , Dupuis Guillaume 
Published: March 2017

Abstract
SMG Microgels are pre-gelled polymers having a narrow size distribution and behaving like large polymer molecules. Their stability is strongly enhanced by internal cross-links. Several SMG microgels having different chemical compositions and cross-link density, with a size of around 2 μm were submited to laboratory corefloodtests. SMG propagation in reservoirs is driven by a size exclusion mechanism. Microgel size prevents invasion of low permeability zones and creates flow resistance in high permeability zones by adsorption on the rock. The permeability cutoff can be tuned by microgel size and chemistry. Permeability reduction generated by SMGs is determined by the thickness of the adsorbed layer which is roughly the size of the microgel in solution. It is little dependent of the adsorption level. Adsorption depends on the chemical composition of the microgel and on the nature of the rock.
An SMG Microgel with soft consistency was selected for a Conformance Control field application in a heterogeneous sandstone reservoir. Reservoir permeability ranges between 10 mD and 1200 mD with an average permeability of around 200 mD. The pattern consists of one injection well surrounded by eleven offset producers. The injection lasted 3 months with a total volume of 9,000 m3. After a few months, six offset producers showed increase in oil rate along with a reduction of a few points of water cut. One well lost both water and oil, thus proving diversion to the other wells. The trend remains steadily established in the pattern with continuous increase in additional oil production. After two years, more than 33,000 bbl of additional oil has been produced, giving a ratio of less than 0.7 lb of microgel per extra barrel of oil.
Harsh Environment Logging-While-Drilling Tools Enhance Well Performance in North Sea HPHT Wells
Authors: Lunney Iain , Duriez Alban , Solbakk Tommy , Skaug Mats Bjørndal , Brian Tom 
Published: March 2017

Abstract
Increases in high pressure, high temperature (HPHT) drilling campaigns on the continental shelf of Norway and the UK have increased demands for next-generation technology that can deliver borehole measurements, enabling the wells to be drilled and reducing the operator's risk and operational expense. These deep gas development and exploration wells require a dramatic departure from conventional operating envelopes, including pressure, temperature, hydraulics, and formation evaluation capability. This paper discusses unique borehole integrity and formation evaluation challenges in two North Sea HPHT wells. It demonstrates how innovative new technology, coupled with fast-track component design modifications to meet specific operational challenges, enabled the safe, cost-effective drilling of these wells.
The development of telemetry, gamma ray, pressure-while-drilling (PWD), vibration, and induction resistivity technology that is rated to operate at 200°C / 25,000 psi followed a stringent life cycle process. In this process, the field trial phase of the technology development included a rapid phase of trial runs, followed by engineering improvements. This iterative process helped to ensure that the technology was fit-for-purpose when it reached the commercialization phase.
The step change in the thermal tolerance of the downhole electronics was accomplished through significant changes in design simplification, thermal screening, ceramic encapsulation, and thermal dissipation modeling relative to existing high-temperature electronics rated to 175 °C.
APRENDIZAJE TECNOLÓGICO E INNOVACIÓN EN REGIONES DE ESCASO DESARROLLO ECONÓMICO. EL PAPEL DE LAS REDES DE COOPERACIÓN
Authors: Valdiviezo Ocampo Guillermo 
Published: March 2017

INTRODUCCIÓN
Cada vez tiene mayor aceptación el que los procesos de aprendizaje tecnológico y la generación de innovaciones y su difusión son un proceso interactivo y de carácter social. Por ello, para autores como Maillat (1996); Maillat y Kebir (1998); Maillat y Grosjean, (1999); Malecki y Oinas (1999); Moulaert y Sekia (1999); Perrin (1991); y Vázquez (1999 y 2002), los factores territoriales inciden de manera importante en las acciones de los agentes emprendedores. Porque se asume que el territorio es capaz de construir un cierto medio que puede estimular los procesos de aprendizaje tecnológico y de innovación, a través de redes y arreglos institucionales que permitan la interacción tanto con actores locales como con agentes externos a la región. ...
DESCENTRALIZACIÓN, DESARROLLO LOCAL Y GOBERNABILIDAD EN CENTRO AMÉRICA (2005) ANGEL SALDOMANDO Y ROKAEL CARDONA
Authors: Morales Barragán Federico 
Published: March 2017

RESEÑA
DESCENTRALIZACIÓN, DESARROLLO LOCAL Y GOBERNABILIDAD EN CENTRO AMÉRICA (2005) ANGEL SALDOMANDO Y ROKAEL CARDONA, SAN SALVADOR, CONFEDERACIÓN CENTROAMERICANA POR LA DESCENTRALIZACIÓN DEL ESTADO Y EL DESARROLLO LOCAL (CONFEDELCA)
“ENREDOS Y SUTILEZAS DEL DERECHO” EN DEFENSA DE LOS BIENES COMUNES. LA HACIENDA SAN PEDRO PEDERNAL DE HUIXTÁN, CHIAPAS. 1790-1865
Authors: Palomo Infante María Dolores 
Published: March 2017

En este artículo se analiza una de las estrategias que los pueblos indígenas utilizaron para defender sus bienes y recursos territoriales durante la primera mitad del siglo XIX. En un marco más amplio, se revisan de igual manera tanto la legislación que afectaba a los asuntos territoriales como los procesos agrarios de Huistán, pueblo del altiplano chiapaneco en el que se localizaba la finca San Pedro Pedernal, alrededor de la cual gira el estudio.
Presentamos cómo fue afectado este pueblo por las diferentes leyes agrarias que entraron en vigor en el México republicano y en el estado de Chiapas; y mostramos a su población luchando por no perder el recurso más importante que poseían: la tierra. En el ámbito de esa lucha se reflejan lo que llamamos “enredos y sutilezas del derecho”, es decir, el uso de recursos legales, y a veces no tan legales, disponibles para alcanzar el fin que se propusieron.