bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast Preparation of Porous MnO/C Microspheres as Anode Materials for Lithium-Ion Batteries
Authors: Su Jing , Liang Hao , Gong Xian-Nian , Lv Xiao-Yan , Long Yun-Fei , Wen Yan-Xuan
Published: May 2017

Porous MnO/C microspheres have been successfully fabricated by a fast co-precipitation method in a T-shaped microchannel reactor. The structures, compositions and electrochemical performances of the obtained MnO/C microspheres are characterized by X-ray diffraction, emission scanning electron microscopy, transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller analysis, charge-discharge testing, cyclic voltammograms, and electrochemical impedance spectra. Experimental results reveal that the as-prepared MnO/C, with a specific surface area of 96.66 m2·g–1 and average pore size of 24.37 nm, exhibits excellent electrochemical performance, with a discharge capacity of 655.4 mAh·g–1 after cycling 50 times at 1 C and capacities of 808.3, 743.7, 642.6, 450.1, and 803.1 mAh·g–1 at 0.2, 0.5, 1, 2, and 0.2 C, respectively. Moreover, the controlled method of using a micro-channel reactor, which can produce larger specific surface area porous MnO/C with improved cycling performance by shortening lithium-ion diffusion distances, can be easily applied in real production on a large-scale.
Successes of Restoration and Its Effect on the Fish Community in a Freshwater Tidal Embayment of the Potomac River, USA
Authors: De Mutsert Kim , Sills Amanda , Schlick C. J. Carroll , Jones R. Christian
Published: May 2017

After a local pollution control plant significantly reduced phosphorus loading into a phytoplankton-dominated tributary of the Potomac River in the early 1980’s, water quality and biological communities were monitored bi-weekly from April-September. After a 10-year time-lag, submerged aquatic vegetation (SAV), once abundant in this freshwater tidal embayment, returned to the area in 1993. After additional reductions in nitrogen load starting in 2000, the system completely switched to a SAV-dominated state in 2005. Fish abundance didn’t change during these distinct phase changes, but the fish community structure did. Increases in SAV provided refuge and additional spawning substrate for species with adhesive eggs such as Banded Killifish (Fundulus diaphanus), which is now the most abundant species in the embayment. Other changes seen were a decrease in the relative contribution of open water dwelling species such as White Perch (Morone americana), and an increase of visual predators such as Largemouth Bass (Micropterus salmoides). The 30-year record of data from this Potomac River tributary has revealed many important long-term trends that validate the effectiveness of initiatives to improve water treatment, and will aid in the continued management of the watershed and point source inputs.
Grid Synchronization of Seven-Phase Wind Electric Generator Using d-q PLL
Authors: Chandramohan Kalaivani , Padmanaban Sanjeevikumar , Kalyanasundaram Rajambal , Bhaskar Mahajan Sagar , Mihet-Popa Lucian
Published: May 2017

The evolving multiphase induction generators (MPIG) with more than three phases are receiving prominence in high power generation systems. This paper aims at the development of a comprehensive model of the wind turbine driven seven-phase induction generator (7PIG) along with necessary the power electronic converters and controller for grid interface. The dynamic model of the system is developed in Maltlab/Simulink. Synchronous reference frame phase-locked loop (SRFPLL) system is incorporated for grid synchronization. The modeling aspects are detailed and the system response is observed for various wind velocities. The effectiveness of seven phase induction generator is demonstrated with the fault tolerant capability and high output power with reduced phase current when compared to conventional 3-phase wind generation scheme. The response of the PLL is analyzed and the results are presented.
Behaviour of Quantum Correlations and Violation of Bell Inequalities in some Noisy Channels
Authors: Erol Volkan
Published: May 2017

Quantum Correlations are studied extensively in quantum information domain. Entanglement Measures and Quantum Discord are good examples of these actively studied correlations. Detection of violation in Bell inequalities is also a widely active area in quantum information theory world. In this work, we revisit the problem of analyzing the behavior of quantum correlations and violation of Bell inequalities in noisy channels. We extend the problem defined in a recent study by observing the changes in negativity measure, quantum discord and a modified version of Horodecki measure for violation of Bell inequalities under amplitude damping, phase damping and depolarizing channels. We report different interesting results for each of these correlations and measures. All these correlations and measures decrease under decoherence channels, but some changes are very dramatical comparing to others. We investigate also separability conditions of example studied states.
Role of Zucchini and Its Distinctive Components in the Modulation of Degenerative Processes: Genotoxicity, Antigenotoxicity, Cytotoxicity and Apoptotic Effects
Authors: Martínez-Valdivieso Damián , Font Rafael , Fernández-Bedmar Zahira , Merinas-Amo Tania , Gómez Pedro , Alonso-Moraga Ángeles , Del Río-Celestino Mercedes
Published: May 2017

Zucchini (Cucurbita pepo subsp. pepo) is a seasonal vegetable with high nutritional and medical value. Many useful properties of this fruit are attributed to its bioactive compounds. Zucchini fruits (“Yellow” and “Light Green” varieties) and four distinctive components (lutein, β-carotene, zeaxanthin and dehydroascorbic acid)were selected. Firstly it was determinated the lutein, β-carotene, zeaxanthin and dehydroascorbic acid content in these fruits and then, in order to measure the safety and suitability of their use  different assays were carried out: (i) Genotoxicity and antigenotoxicity tests to determine the safety and DNA-protection against hydrogen peroxide; (ii) cytotoxicity and (iii) DNA fragmentation assay to evaluate the proapoptotic effect. Results showed that: (i) all the substances were non-genotoxic, (ii) all the substances were antigenotoxic except the highest concentration of lutein, (iii) “Yellow” Zucchini epicarp and mesocarp exhibited the highest cytotoxic activity (IC50 > 0.1 mg/mL and 0.2 mg/mL, respectively) and iv) “Light Green” Zucchini skin and pulp induced internucleosomal DNA fragmentation . To sump up, Zucchini fruit could play a positive role in human health and nutrition due to this fruit and its components were safe, able to inhibit significantly the H2O2-induced damage and exhibit antiproliferative and pro-apoptotic properties toward HL60 tumour cells. The information generated from this research should take into account to select potential accessions for breeding programs purposes.
Novel Combination of Withaferin A and Sulforaphane Inhibits Epigenetic Machinery, Cellular Viability and Induces Apoptosis of Breast Cancer Cells
Authors: Royston Kendra , Udayakumar Neha , Lewis Kayla , Tollefsbol Trygve
Published: May 2017

With cancer often classified as a disease that has an important epigenetic component, natural compounds that have the ability to regulate the epigenome become ideal candidates for study. Humans have a complex diet, which illustrates the need to elucidate the mechanisms of interaction between these bioactive compounds in combination. The natural compounds withaferin A (WA), from the Indian winter cherry, and sulforaphane (SFN), from cruciferous vegetables, have numerous anti-cancer effects and some report their ability to regulate epigenetic processes. Our study is the first to investigate the combinatorial effects of low physiologically achievable concentrations of WA and SFN on breast cancer cell proliferation, histone deacetylase1 (HDAC1) and DNA methyltransferases (DNMTs). No adverse effects were observed on control cells at optimal concentrations. There was synergistic inhibition of cellular viability in MCF-7 cells and a greater induction of apoptosis with the combinatorial approach than with either compound administered alone in both MDA-MB-231 and MCF-7 cells. HDAC expression was down-regulated at multiple levels. Lastly, we determined the combined effects of these bioactive compounds on the pro-apoptotic BAX and anti-apoptotic BCL-2 and found decreases in BCL-2 and increases in BAX. Taken together, our findings demonstrate the ability of low concentrations of combinatorial WA and SFN to promote cancer cell death and regulate key epigenetic modifiers in human breast cancer cells.
Quantum Correlations and Bell Inequality Violation under Decoherence
Authors: Erol Volkan
Published: May 2017

Quantum Correlations are studied extensively in quantum information domain. Entanglement Measures and Quantum Discord are good examples of these actively studied correlations. Detection of violation in Bell inequalities is also a widely active area in quantum information theory world. In this work, we revisit the problem of analyzing the behavior of quantum correlations and violation of Bell inequalities in noisy channels. We extend the problem defined in [1] by observing the changes in negativity measure, quantum discord and a modified version of Horodecki measure for violation of Bell inequalities under amplitude damping, phase damping and depolarizing channels. We report different interesting results for each of these correlations and measures. All these correlations and measures decrease under decoherence channels, but some changes are very dramatical comparing to others. We investigate also separability conditions of example studied states.
Factory Tour of Mimaki Engineering Co. Ltd.
Authors: Yamazaki Yasunori ,   Nagano National College of Technology
Published: May 2017

Mimaki Engineering Co. Ltd., founded in the city of Tomi, Nagano Prefecture in 1975 and listed on the JASDAQ Stock Exchange in 2007, is an up-and-coming company. At first, the company developed and manufactured the special order item like the electrical equipment unit, the chip mounter, and the automatic transfer line system, etc., which were the “Engineering” still remaining in the name of the company. The Company’s first ever original product was a pen plotter which made the best use of the servo technologies cultivated in earlier experiences in producing custom-made products. This then led to the development of cutting plotters that utilize cutters instead of pens. Knowledge gained on the needs and characteristics of the Company’s mainstay market seems to have opened the door to the later commercial success of the company. The product that has most influenced the direction of the company has been the large-size ink jet printer put on the market in 1996. The company, in order to meet the needs of sign graphics (the company’s mainstay market), has added new inks and technologies for large-sized printing to the fundamental ink jet technologies introduced by Epson, and in so doing has grown into a leading company in the field. Moreover, the Company has steadily prepared to advance into the field of industrial products with printing and cutting technologies applied to plastic plates, etc. and also into the textile and apparel field, in which printing is done on fabric. These technologies all provide main stay products for digital on-demand production, an innovative production method.
Development of an Environmentally Friendly Oil Based Drilling Fluid Using Castor Oil with Polar Activator and In Presence of Strong Bases Lime
Authors: Bastidas H. A. , Perez J. S. , Castellanos C. Vargas
Published: May 2017

The behavior of two Castor oil based muds (OBM) prepared with additives marketed in Colombia is observed, the concentrations of the additives are the same for both fluids with the difference that one has as rheological modifier a polar activator and the other uses lime. These ones are subjected to rolling up for 16 hours at temperatures of 65°C, 80°C and 120°C. The rheological behavior of the fluids is analyzed according to API RP 13B-2 standard before and after rolling up at different temperatures. According to the results of this investigation, it is discovered that the fluids behavior in the presence of strong bases like lime becomes stable as the rolling up temperature increases until 120°C, whereas when there is no lime in the composition the behavior is more constant in all the cases and the change of viscosity with respect to the initial viscosity is smaller. The presence of strong bases tends to decrease their percentage of fatty acids 17% at 65°C and increase 6% at 120°C with respect to the fluids with polar activator rolled up at the same conditions. To see if the fluids can be categorized as environmentally friendly, we proceeded to evaluate the impact of the fluids developed in the survival of red tilapia fingerlings in a water body simulated in the laboratory. The minimum conditions to die at least 50% of the population of red tilapia fingerlings was 96 hours of exposure to fluids at a concentration of 5000ppm.
Identification of CO2 with Magnetic Resonance Key to Understanding Production Behavior in Campo Palo Azul, Ecuador: A Case Study
Authors: Ramirez N. X. , Roldan J. E. , Delgado B. , Cuenca D.
Published: May 2017

This paper presents a case study focusing on the identification of CO2 in the Hollin reservoir, based on nuclear magnetic resonance (NMR) responses, its effect on petrophysical parameters, and the negative effect on production wells. The paper also discusses the strong relationship between the high CO2 concentration in the reservoir fluids and its effect on the formation damage resulting from pore throat plugging from organic and inorganic compounds.

After NMR processing, it was possible to identify the CO2 response on porosity related to low hydrogen index; the PVT analysis reveals approximately 75% of CO2 in the reservoir conditions and more than 95% of CO2 in the surface conditions. Asphaltene stability was evaluated through four methods, including the Leontaritis method, colloidal stability index, Stankiewicz method, and stability crossplot (SCP), which enabled the determination of an unstable probability by more than 75%. Palo Azul wells have been completed with production enhancement techniques, such as fracturing, to minimize the formation damage and its negative production effect; until now, however, the unique hypothesis considered formation damage to be related to fine-grain migration without considering that the primary problem could be connected to asphaltene stability. The deposition of the asphaltene can plug pore throats, reducing wellbore permeability and dramatically reducing fracture wings conductivity.

This case study provides several important contributions. First, NMR results were successfully used in the Oriente basin of Ecuador to identify reservoirs with high concentrations of CO2. Second, four different diagnostic methods were used to determine asphaltene stability; this has altered common paradigms regarding production reservoir behavior. Finally, this case study enabled the development of a new technical hypothesis concerning additional factors that can contribute to formation damage in the Hollin reservoir.
An Appropriate Waterflood or Waterdrive Performance Analysis for any Oil/Water Viscosity Ratio
Authors: Tillero E. , Mogollon J. L.
Published: May 2017

This paper presents an extension of Yang's Y-function method (a function of oil fractional flow) aiming to improve performance analysis of a mature waterflood or waterdrive reservoir for any oil-water viscosity ratio condition. The new approach is based on an appropriate mathematical expression that substitutes the traditional semilog linear relationship between the oil-water relative permeability ratio and water saturation. The production decline analytical method to diagnose waterflood performance as proposed by Yang (2009a and 2009b) and derived from the solution of the one-dimensional (1D) frontal advance Buckley-Leverett (BL) equation, applies to reservoirs with water breakthrough starting from semilog linear section of the kro/krw vs water saturation plot and with moderate oil-water viscosity ratios. To solve this flow equation, the fractional flow curve, which is function of oil and water viscosity and also oil and water relative permeability ratio, must be known. The traditional semilog linear relationship of oil-water relative permeability ratio for intermediate water saturation range has been consistently used to solve fractional flow and then the BL equation. Because the water saturation at breakthrough (Swbt) moves to the boundaries of the water saturation range at both very unfavorable and favorable oil-water viscosity ratio, the use of the traditional semilog linear trend to both extreme conditions of oil-water viscosity ratio could lead to unrealistic oil prediction during the productive period of waterflooding or waterdrive. Therefore, a representative oil-water relative permeability ratio and water saturation approach of the reservoir rock is necessary to obtain reliable predictions at and after water breakthrough.

This paper presents the use of the resulting expression of solving the derivative (with respect to water saturation) of the quotient between individual power-law expressions of relative permeability for both oil and water phases, specifically from Corey's correlations of relative permeability curves. The resulting term named B' that substitutes the constant parameter B in the Y-function is presented in this work. Theoretical and field data examples are also presented to illustrate this approach.

Results show that the new approach (the comprehensive Y-function, cY) derives a solution with a slope m that can be different than -1 for a normal displacement efficiency from the log-log plot of Y vs. tD, therefore m value from real field data will reflect the displacement efficiency imposed by reservoir characteristics and/or operational conditions. This new approach also improves reliability when calculating the volumetric sweep efficiency (areal sweep efficiency times vertical sweep efficiency) and predicting both water and oil cut of mature waterflood or waterdrive reservoirs. It also expands the Yang's model application by improving its performance during both very unfavorable and favorable oil-water viscosity ratio, particularly at and after water breakthrough.
New Borehole Imaging for OBM Systems. Auca Mahuida Volcano and Las Manadas Fields, Neuquen, Argentina
Authors: Mallimaci D. , Ribas S. , Paris M. , Grisolia J. , Crespo G.
Published: May 2017

The Auca Mahuida Volcano and Las Manadas field produces oil and gas from the Mulichinco, Lower Centenario and Rayoso formations. However this high quality reservoir has been severely damaged due to volcanic activity.

This volcanism occurred after the main hydrocarbon migration and trapping, although there are hydraulically isolated bodies related to the igneous intrusions, confirmed from pressure testing and the distribution of the fluid along the stratigraphy column. The attitude and distribution of these intrusions in the reservoir is not generally known in part due to the lack of the surface seismic over this geologically complicated area.

The big challenge is to be able to accurately identify and rank the intrusive igneous features such as dykes, sills, laccolith and other geological features.

A new borehole image was introduced in Argentina for oil based mud systems. It has very good coverage with 80% in 8 inch wells. It is composed of 6 pads mounted in 6 independent articulated arms, each pad has 10 sensors resulting 60 micro-resistivity measurements. This tool works on different frequencies for different formation resistivity range. Depending on the known resistivity two frequencies can be simultaneously selected to acquire two images in one single pass. Recommended logging speed is 5.5 m/min.

As a result of the operations more than 2000 meters have been logged with high quality borehole imaging. In spite of hostile weather conditions and because it is a natural protected area, there were no incidents registered during these jobs.

At this point of the project dykes seem to follow pre-existing fractures to intrude the formations so the recognition of the fracture attitude is very important to prevent those intrusions at depths where the oil and gas is trapped.

This information was considered as a high value to improve the existing geological model, providing knowledge about the complex net of intrusive bodies by the accurate recognition of the type of intrusion and its attitude close to the borehole.
Thermodynamic Behavior of Olefin and Methane Mixtures Applied to Synthetic Drilling Fluids Well Control
Authors: Marques D. C. , Ribeiro P. R. , Santos O. L. , Lomba R. F.
Published: May 2017

The pre-salt discoveries in deep water have evidenced a challenging environment for drilling operations because of the technical demand and restriction and also environmental regulations fomenting technological development.

Inaccurate estimation of the pressure could lead to drilling problems such as kick, lost circulation and wellbore instability. In this context, understanding the drilling fluid and gas formation mixture behavior is essential in situations of gas influx from the formation into the wellbore. These evidence the drilling fluids importance for the drilling operational efficiency, safety and cost reduction.

Since the synthetic based drilling fluids are more sensitive to the pressure and temperature variations than water based drilling fluids, the effect of pressure, temperature and mixture composition on the thermodynamic properties such as density, formation volume factor, solubility ratio and saturation pressure were determined based on PVT (pressure/temperature/volume) experimental measurements for methane and olefin mixtures. Those properties are crucial for the mixture volumetric behavior knowledge at downhole conditions especially when gas enters into the wellbore.

The experiments were conducted in isothermal conditions and a gas enrichment experimental procedure was applied. The temperature was set at a range between 25°C and 80°C while the gas molar fraction ranged from 30% to 50% and pressures up to 70 MPa.

Additionally, the data collected was compared with the teamwork database for methane and n-paraffin mixtures and methane and ester mixtures. According to the literature, olefins show less toxicity and better biodegrability when compared to isomerized paraffins and esters, therefore olefins fit in with the new requirements present by the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA), which restricted the disposal of cuttings associated with paraffins in offshore operations.

Moreover, as each base has its own particularity, the findings exhibited the importance of the methane and olefin mixtures behavior knowledge at downhole conditions to guarantee the operational safety and efficiency. The experimental data will be essential to bring well control software up to date, which helps the decision-making of the engineers during well control.
Downhole Linear Reducer Application for Rod Load Optimization
Authors: Dominguez E. , Yorio P. , Ferrigno E. , Piña J. L. , Somoza M.
Published: May 2017

The present work aims to expose the study and development of a potentially disruptive change of focus in the mechanical sucker rod artificial lift system. This is a new solution based on the installation of a linear speed reducer located at the bottom of the well between the pump and the rods. This new configuration pursues the goal of dramatically reducing loads on the rod string, surface equipment and power motor, thus allowing to expand, in efficiency and field of application, the limits of the sucker rod pumping, and in some cases of the artificial lift systems as a whole.
Optimization and Enhanced Productivity Study in the Furrial Field
Authors: Peretti Leiva F. C. , Gonzalez S. J. , Zabala C. L. , Molina G. , Rondón A. K. , Jeschke Z. A. , Camejo M.
Published: May 2017

Located in eastern Venezuela, the Furrial field is composed of three main reservoirs. Reservoir characteristics include 8,300 million barrels of original oil in place and a hydrocarbon column consisting of crude with asphaltenes that vary from 10 to 30° API. The field has 147 active wells, of which 45 are water-injector wells and seven are gas-injector wells. Wells drilled in the area range from approximately 12,000 to 17,000 ft. Crude oil with asphaltenic tar mats (because of its chemical features) was identified in the field, which establishes a vertical structural seal bordering traditional reservoirs. Major problems in the reservoirs include emulsions, paraffin and asphaltene plugging, water cuts, and water channeling. For several years, the operator has been developing a program to convert wells that cannot be produced naturally to gas-lift wells (conventional, tubing punch, and coiled lift) to increase recovery potential. Although the system is a single, economic, and fast-lifting system, it requires a continuous flow of high-pressure gas.

The productivity workflow presented in this paper required a multidisciplinary team to analyze, select, and rank recommended well candidates for intervention and production optimization, evaluating all aspects pertaining to well productivity and reserves to objectively identify possible alternatives for increasing production. The process produced a list of wells ranked by their potential to increase production. The intervention plan for the wells were then defined and ranked based on technical and economic criteria.

This paper presents the successful application of this methodology in a mature field in the Venezuelan Oriente Basin and demonstrates how the method impacted and improved well productivity in this field by over 27 times more than the base case.
Multipay Well Completion in Argentina: A Versatile Pinpoint Completion Technology Applied through Several Conventional, Tight, and Shale Reservoirs
Authors: Bonapace J. C. , Kovalenko F. , Sorenson F. , Forni P. , Capsa Grupo , Barbalace F.
Published: May 2017

Many fields in Argentina have multilayer reservoirs that require various stimulation techniques, primarily hydraulic fracturing. A variety of formations and types of reservoirs, such as conventional (mature fields) and unconventional (tight gas and shale), are the main focus in the Golfo San Jorge and Neuquén basin. The hydraulic fractures created in these basins present a variety of conditions and challenges related to depth, well architecture design, bottomhole temperature (BHT), reservoir pressure, and formation permeability.

In 2006, a pinpoint completion technique was introduced to help achieve greater efficiency and reduce time and costs associated with completions. This paper presents experiences gained using this technology and proving such versatility in different types of reservoirs.

The pinpoint technique, called hydrajet perforating annular-path treatment placement and proppant plugs for diversion (HPAP-PPD), was applied in new wells at different reservoir conditions. The history and evolution of this technique in Argentina was initiated in conventional oil reservoirs (mature fields in Golfo San Jorge) and then was introduced in the Neuquén basin in gas well completions. Throughout the last seven years, this technique has been tested and implemented in tight gas wells. More recently, it was used to improve a completion technique in a shale oil well.

This completion method allowed operators to focus treatments in desired zones using specific treatment designs based on reservoir characteristics. Several case histories are presented for different basins, formations, and reservoirs types, highlighting lessons learned and reduced completion time.
Fully Compositional Integrated Subsurface-Surface Modeling for Critical Gas Condensate Reservoirs: Santa Barbara and Pirital Fields, Venezuela.
Authors: Pérez J. G. , Cabrera C. J. , Lopez L. R.
Published: May 2017

This paper presents the workflow and learned lessons during the construction of a fully compositional integrated subsurface/surface model for the Santa Barbara and Pirital fields, which are important oil production units located to the east of Venezuela. In this approach, the numerical reservoir simulation models, wells and surface facilities were coupled in order to obtain production profiles considering both changes in the reservoir conditions and surface restrictions, achieving an assertive planning of asset development.

The applied methodology is based on the construction of more than 150 compositional well models, performing sensitivity analysis to define multiphase flow correlations for vertical pipe and chokes. A network model, which comprises more than 900 Km of lines, 3 main flow stations, and 3 separation levels, was also built in compositional mode honoring line sizes, lengths and elevation changes. Two numerical simulation models represent the most reliable characterization of the main reservoirs. Each model was initialized and ran separately, in order to discard internal inconsistencies. Then, the integration was performed considering the sand face on the wells as the coupling point.

The integrated asset modeling allowed predicting the production behavior of the reservoirs taking into account the constraints of the surface facilities, reducing the uncertainty of forecasts and identifying limitations and bottlenecks at surface level. It was also possible to accurately determine the details of the hydrocarbons streams (NGL) at different pressure stages of the network, which reasonably matched with field data (less than 3% of difference). The result is a versatile tool for the integrated asset management, which allows to sensitize all the elements of the production chain and estimate how each one affect the performance of the asset, discarding the division between departments upstream and downstream and establishing a common management strategy for all disciplines.

The novelty of this work is based on the challenge of building fully compositional coupled models considering giants and complex reservoirs with large surface networks. The proposed methodology and learned lessons will certainly serve as reference for similar future works.
Study of Nanoparticle Adsorption and Release in Porous Media Based on the DLVO Theory
Authors: Abdelfatah E. R. , Kang K. , Pournik M. , Shiau B. , Harwell J. , Haroun M. R , Rahman M. M.
Published: May 2017

Nanoparticles are usually small enough that they can pass through the porous media without mechanically plugging the pore throats. However, physicochemical interaction between the nanoparticles and the pore walls can cause significant retention of nanoparticles. The objective of this paper is to provide theoretical equations based on DLVO theory to calculate the rate of deposition and release at different temperatures, ionic strengths, and pH values.

DLVO theory is used to understand the interaction between nanoparticles and rock minerals. Electrostatic interaction depends on the zeta potential of nanoparticles and pore surface. In this paper, an equation is developed to calculate zeta potential at different temperatures, ionic strengths, and pH values. The rate of deposition and release of Silica nanoparticles in a sandstone formation, where interaction energy profile has energy barrier, has been derived. To validate the theoretically calculated rates, a numerical model is developed to compare the theoretical calculations with experimental data.

Increasing ionic strength and temperature decreases the energy barrier height and hence increases the rate of deposition. The effect of pH on the rate of deposition depends on the location of environment pH with respect to the isoelectric point of nanoparticles and rock surface. For extreme values of pH, energy barrier exists and rate of deposition is low. However, when the pH of the solution is between the isoelectric points of nanoparticles and rock surface, the energy barrier decreases and the rate of deposition increases. The rate of deposition is time dependent with the rate decreasing as more rock surface is covered by nanoparticles. These theoretically calculated rate values are used in a numerical model of the advection-dispersion equation with source/sink term. Several experimental data have been perfectly matched with the model that validates the theoretical calculations of the rate of deposition.

The new mechanistic model for nanoparticles can be used to determine the fate of nanoparticles in porous media under different conditions of nanoparticle size, temperature, ionic strength, and pH. This model can help to understand the nanoparticles transport in porous media and effectively design nanoparticles fluid for injection into oil and gas reservoirs.
Grimbeek2: First Successful Application Polymer Flooding in Multilayer Reservoir at YPF. Interpretation of Polymer Flooding Response
Authors: Juri J. E. , Ruiz A. M. , Pedersen G. , Pagliero P. , Blanco H. , Eguia V. , Vazquez P. , Bernhardt C. , Schein F. , Villarroel G. , Tosi A. , Serrano V.
Published: May 2017

Here we report the key success factors of the first polymer pilot at YPF in the south of Argentina and the consensus shifting strategy for polymer expansion in the current oil price context.

We calculated water flow velocities in the reservoir using three multiscale history matched simulation models. We found that more than 80% of water velocities across the complete field are below1ft/day [normally assumed reservoir water velocity for calculating the resistance factor in laboratory experiments].We increased polymer concentration in 10 to 30% to ensure good mobility ratio in the high permeability streaks possibly located in the channel bars. This is very important because low end point water permeability (<0.09) could explain the success of water flooding in friable formation with viscous oil. This challenges the common assumption of poor performance because adverse mobility ration (> > 10). High permeability streaks (above 10 Darcy) are not characterised because they are often lost during coring or they are not suitable for coreflooding experiments. Instead, stochastic history matching supports the idea of greater water end point permeability (>0.2) in the high perm streaks. Then, the target resistance factor for polymer could be underestimated (underestimation of polymer concentration) and polymer injection might not perform as expected. Simulation-based analysis of flows in the pilot zone strongly suggests that one of the key success factors was pattern confinement. The pilot configuration is five-spot with 4 injectors, 1 confined producer and 9 offsets producer wells. After injecting 0.15 pore volumes of 2500/3000ppm polymer we recovered more than 11% ooip incremental oil above waterflooding from the central pattern and more than 6% of the ooip from offset producers in contacted zone. The water cut reduced from 90% to 45% in the confined producer and from 87% to 67% in the offset producers. Water cut reduction and therefore the oil response is greater than best pilots in the literature. This can be explained because of the cross flow between fluvial layers in the inter-well region. Our simulations indicated that there was no out-flow of the central pattern. The very good performance in terms of low utility factor obtained so far (2.9 kg per incremental barrel of oil above water flooding) supports the hypothesis of the good confinement. The accurate simulation model allowed us to conceptualise a pattern rolling strategy for the polymer expansion that makes this technology economic for this low oil price context.
Reversing Well Failure Trends in Shushufindi Increases Production and Reduces Costs through the Application of New Operating Practices and Technologies
Authors: Gozalbo E. , Rodriguez J. C. , Carrera J. , Marquez D. , Meza D. I. , Gornescu B. C. , Reyes D. , Leon R.
Published: May 2017

The giant Shushufindi (SSFD) field, located in the Amazon basin of Ecuador is a mature field that has been producing since 1972. In December 2011, management of the field was awarded to Consorcio Shushufindi (CSSFD) by PetroAmazonas EP (PAM) with the signature of a 15 year integrated services contract. At the time of contract signature, field production was 45,000 BOPD from 90 wells. Since then, 109 new wells and 91workovers have been completed by CSSFD, raising production to 90,000 BOPD in early 2016.

Along with the implementation of a field development plan, key elements, such as the deployment of new processes, operating practices, and technologies, to address deferred production were identified. Production challenges in SSFD were increasing in frequency and severity, and the need for frequent well reviews became a priority.

The processes implemented targeted the reduction of production deferment due to well downhole failures by identifying the root cause, planning for remedial actions, and following-up on execution. An initial field-wide evaluation of production deferment causes allowed implementing the process at a large scale rather than on a well-by-well basis. Project management was applied to prioritize actions and materialize the savings in production and costs.

To accelerate implementation, a pragmatic approach based on experience was initially used, after which the process became fully defined and documented. Main areas tackled were Electrical submersible pump (ESP) design and new technologiesTubing design and selectionProduction chemistry program adjustmentsWell monitoring and surveillance using operation support centers (OSC)Well servicing (pulling) operational efficiency

The improvements were followed by the collection and analysis of field data and results for a period of 5 years and have resulted in an increase in average well run life of over 1 year. Production deferment related to well failure was also decreased from 4.7% to 1.6% of total production, increasing the oil recovery by 1.3 million STBO.

The evaluation of the improvements was done over a period of 5 years (January 2012 to November 2016) where the field data was good enough to carry on the analysis.
Tackling the Challenges of a Mature Field with Multiple Oil-Water Contacts Generated in Major Reservoir Hydraulic Units: Case Study in the Shushufindi-Aguarico Field, Oriente Basin, Ecuador
Authors: Naranjo M. A. , Freire J. L. , Lafournère J. P. , Pastrana W. , Hurtado J. , Bourge J. P. , Vargas A. , Cortez O. , Bringer F. , Izurieta A.
Published: May 2017

The Shushufindi-Aguarico field (SSFD), located in the Oriente basin of Ecuador, has been under production since1972. In December 2011, when Consorcio Shushufindi (CSSFD) joined efforts with the national oil company PetroAmazonas EP (PAM), there were about 150 wells in the field with a production of 45,000 BOPD. Since then, 109 new wells and 91workovers have been completed in the field, raising the production to 80,000 BOPD by August 2016.

Reservoir characterization of the SSFD field was undertaken with sequential objectives in mind. First, to answer the project needs for primary recovery, the effort focused on the main reservoirs (Lower U and Lower T) to create the annual work plans for the initial years of the project. Thereafter, a more refined petrophysical analysis, production data re-evaluation, and individual well diagnosis for water production provided the necessary characterization results for the field development plan (FDP) with a thorough mapping of the hydraulic units (HUs). In Shushufindi-Aguarico field, stratigraphic compartmentalization occurs when flow is prevented across sealed boundaries within the reservoir. These boundaries are caused by a variety of geological and dynamic factors.

The characterization of the heterogeneity in the U and T reservoirs was a key starting point in understanding how lithology controls the horizontal and vertical movement of fluids, the reservoir depletion mechanisms, and the different completion options for a specific well.
Designing Environmentally Conforming Drilling Fluids: Challenges and Considerations in Latin America
Authors: Fornasier F. C. , Campo M. , Djuric A. , Obando D. M.
Published: May 2017

When planning drilling operations for an oil or gas well, drilling fluid is a key factor to consider for a successful operation. Fluid selection depends primarily on two aspects. First, it must meet all specific technical requirements for the well. Second, it must comply with environmental regulations. Therefore, this selection should be evaluated in detail through specialized laboratory testing and engineering analysis. Factors, such as chemical selection, engineering, processes, and field execution contribute to both the conformance and performance of a drilling fluid.

Technical requirements for a drilling fluid are distinct for each operation. However, in general terms, a drilling fluid should ensure wellbore stability, optimize drilling rates, provide effective hole-cleaning rheological properties, minimize pressure spikes while circulating, and transmit hydraulic power to downhole tools. Environmental requirements are region-specific and vary in terms of complexity, from relatively simple guidelines to manage parameters, such as ionic concentration limits, to specific chemical qualifications, such as bioaccumulation, biodegradation rates, and toxicity thresholds. To satisfy both technical and environmental requirements, fluid designs should be fine-tuned and customized in each region.

A principal drilling operation objective is to minimize safety and environmental risks. As a result, operators and service companies take proactive initiatives to help minimize the likelihood of these risks during drilling operations.

Personnel involved in drilling operations should know and comply with the directions in the drilling permit to help avoid environmental and safety incidents. Additionally, all personnel are encouraged to report potentially hazardous activities or circumstances through a variety of observational safety programs.

The purpose of this technical paper is to provide knowledge for the oil and gas industry to help understand the governmental permissions in the Latin American region and considerations for selecting ecologically compatible drilling fluids and products in the region.
Integrated Services in Well Construction Collaborate to Reduce Well Delivery Time by 45% in the Carabobo Area, Orinoco Oil Belt in Venezuela
Authors: Pabón C. A. , Hernandez O. A. , Plazas I. , Urbano E.
Published: May 2017

Billions of barrels of extra-heavy crude oil and bitumen deposits are present in Venezuela, with most located in the Orinoco Oil Belt (OOB). The OOB, which is situated in southeastern Venezuela, is one of the largest, essentially untapped, oil accumulations in the world. The belt stretches 700 km from east to west to the north of the Orinoco River, with an area of approximately 54 000 km2. The OOB is composed of soft, unconsolidated reservoir sands dating from the Miocene age.

The Carabobo block extra-heavy oil reservoirs are categorized by three gross intervals—Lower, Middle, and Upper Morichal formations—which are at a shallow true vertical depth (TVD) of less than 3,500 ft and consist of abrasive sands. Development is typically through the use of extended horizontal wells. Cuttings bed circulation and removal is one of the main challenges in these well types and can normally be alleviated by increasing rotation speed, but the abrasiveness of these formations could cause additional vibration, wear, and/or damage to directional tools.

In a coordinated effort, the operator followed several steps to apply best drilling practices in this area. The first phase was implementing a customized project management (PM) model that organized discrete drilling service contracts under a centralized structure. The ultimate purpose was to drill wells faster in a safe environment with the least nonproductive time (NPT) possible, delivering the wells to production while maximizing efficiency in the field.
Handling Decommissioning and Restoration Liabilities within PRMS and their Impact on Reported Reserves of Producing Fields Approaching Abandonment
Authors: Harrison Bob , Falcone Gioia
Published: May 2017

It is estimated that nearly 150 fields may cease production by 2020 on the United Kingdom Continental Shelf (UKCS), requiring tens of billions of dollars to be spent on decommissioning and restoration (D&R) to remove platforms and development wells. Unfortunately, SPE's Petroleum Resource Management System (PRMS) offers limited guidance on how to handle D&R liabilities, even though such costs impact on whether late-life producible hydrocarbon volumes from a mature field can be classified as reserves.

The economic limit test (ELT), which ignores any costs related to abandonment, is described in the PRMS as the date when net operating cash flow (NOCF) becomes negative, and it defines the reserves to the end of commercial producing life. However, with the agreement of government regulators, some North Sea field operations continue at negative NOCF to defer abandonment expenditure (Abex) and to maximize recovery. Therefore, a discontinuity can occur when subsequently calculating the point forward net present value (NPV) of the developed project, which must include D&R costs, and which leads to the developed project's NPV becoming negative, even though there is a positive ELT to some future date. Recoverable hydrocarbon volumes must be commercial to be classified as reserves, so we have an increasingly common state of affairs where mature fields in the North Sea continue to produce, but should perhaps be reclassified as contingent resources. Operators will find it far more difficult to get loans from banks or attract investor funding if their reserve base is eroded. The PRMS has an implicit, but unstated assumption that the operators of developed projects have arranged financing for D&R liabilities, yet some operators of mature producing fields, who are stil negotiating such cover, argue that the tail-end produced volumes can be booked as reserves in accordance with the vague guidance in the PRMS.

The paper discusses this discontinuity between ELT and point forward NPV, as well as issues around abandonment in the region, methods to finance D&R and safeguard against default, differing views of how D&R costs should be handled within PRMS, and their impact on project classification. The definition of D&R within PRMS is critically reviewed, with formal responses solicited from the SPE Oil & Gas Reserves Committee (OGRC). Finally, the paper suggests changes to the PRMS are needed to make it more suitable for characterizing mature assets that are approaching abandonment.