bluuebunny/crossref_metadata_2025 huggingface dataset:
Physicochemical and electrochemical properties of imidazolium ionic liquids: Cycling performance of low cost lithium ion batteries with LiFePO4 cathode
Authors: Srour Hassan. , Rouault Hélene. , Santini Catherine C.
Published: December 2013

This manuscript reports investigation conducted on room temperature ionic liquids (RTILs) C1CnImNTf2/n=4, 6 in order to use it as electrolyte solvent in lithium ion battery. The ionic conductivity, viscosity, ion self-diffusion coefficients, and electrochemical stability in C1CnImNTf2 are presented. A solution of C1CnImNTf2/n=4, 6 containing 1.6 mol.L-1 of LiNTf2 has been used as the electrolyte in a Li-ion battery with graphite and LiFePO4 as respectively negative and positive active materials. [Li][C1C6Im][NTf2] shows the best cycling performance: a capacity up to 120 mAh.g-1 at C/10 rate at 25°C.
THE MECHANICAL PROPERTIES OF POROUS ALUMINUM USING FINITE ELEMENT METHOD SIMULATIONS AND COMPRESSION EXPERIMENTS
Authors: Larner Max , Dávila Lilian P.
Published: December 2013

Lightweight porous metallic materials are generally created through specialized processing techniques. Their unique structure gives these materials interesting properties which allow them to be used in diverse structural and insulation applications. In particular, highly porous Al structures (Al foams) have been used in aircraft components and sound insulation; however due to the difficulty in processing and random nature of the foams, they are not well understood and thus they have not yet been utilized to their full potential. The objective of this project was to determine whether a relationship exists between the relative density (porous density/bulk density) and the mechanical properties of porous Al structures. For this purpose, a combination of computer simulations and experiments was pursued to better understand possible relationships. A Finite Element Method (FEM)-based software, COMSOL Multiphysics 4.3, was used to model the structure and to simulate the mechanical behavior of porous Al structures under compressive loads ranging from 1-100 MPa. From these simulated structures, the maximum von Mises stress, volumetric strain, and other properties were calculated. These simulation results were compared against data from compression experiments performed using the Instron Universal Testing Machine (IUTM) on porous Al specimens created via a computernumerically-controlled (CNC) mill. CES EduPack software, a materials design program, was also used to estimate the mechanical properties of porous Al and open cell foams for values not available experimentally, and for comparison purposes. This program allowed for accurate prediction of the mechanical properties for a given percent density foam, and also provided a baseline for the solid Al samples tested. The main results from experiments were that the Young’s moduli (E) for porous Al samples (55.8% relative density) were 15.9-16.6 GPa depending on pore diameter, which is in good agreement with the CES EduPack predictions; while the compressive strengths (σc) were 155-185 MPa, higher than those predicted by CES EduPack. The results from the FEM simulations using 3D models (55.8% relative density) revealed the onset of yielding at 13.5-14.0 MPa, which correlates well with CES EduPack data. Overall results indicated that a combination of experiments and FEM simulations can be used to calculate structure-property relationships and to predict yielding and failure, which may help in the pursuit of simulation-based design of metallic foams. In the future, more robust modeling and simulation techniques will be explored, as well as investigating closed cell Al foams and different porous geometries (nm to micron). This study can help to improve the current methods of characterizing porous materials and enhance knowledge about their properties for alternative energy applications, while promoting their design through integrated approaches.
The effect of reactive ion etching parameters on the electrical properties and the removal of residual organics in spin-coated colloidal ITO films
Authors: Joshi Salil M. , Gerhardt Rosario A.
Published: December 2013

Spheroidal colloidal indium tin oxide (ITO) nanoparticles, about 6 nm in diameter, were synthesized in-house and films were fabricated from them on glass substrates by spin coating. These films had high electrical resistivity due to the presence of organic capping ligands around each nanoparticle. Although high temperature annealing has been shown to reduce film resistivity by over eight orders of magnitude, lower temperature processing is desirable for applications like flexible electronics. Colloidal ITO films were subjected to a series of alternating RIE treatments in oxygen (5 minutes duration per cycle) and in argon (1 minute duration per cycle); and parameters such as gas pressure, RIE power and number of cycles were varied. These RIE treatments were found to reduce the film resistivity significantly. Among the parameters studied, gas pressure during RIE was found to be the most important parameter that determined the effectiveness of the treatment. Residual carbon content variation characterization done by XPS depth profiles also indicated similar trends.
Self-assembly Gold Nanoislands for Localized Surface Plasmon Resonance Biosensing
Authors: Lawrence Wu Chi-Man , Ng Siu-Pang
Published: December 2013

Localized surface plasmon resonance (LSPR) is a label-free biosensing technique employing plasmonic nanostructures to detect local refractive index change induced by biomolecules in the vicinity of these nanostructures. In analogy to surface plasmon resonance (SPR) sensor in a cuvette, LSPR is resistant to bulk refractive index fluctuation yet remains comparably sensitive for biosensing purpose. LSPR has the advantage over SPR in that the overall system size is smaller, and not affected by normal temperature fluctuations during measurement. However, mass production of a cheap but effective LSPR substrate remains challenging. In this paper, a self-assembly gold nanoisland structure was synthesized on transparent glass substrate by a simple two-step deposition-growth process. The first step involved depositing an ultra thin film of gold with nominal thickness of 5 nm by thermal evaporation at 1× 10-7 torr. Then the gold coated substrate was placed into a high temperature oven and annealed at 450°C for 10 hours. By first observation, the annealed substrate turned from pale green to dark pink. Upon scanning with atomic force microscopy, it was revealed that nanoislands of about 100 nm to 150 nm wide with average height of 60 nm were formed. Optical extinction measurements showed that the absorption peak was about 560 nm with fullwidth-half-maximum of 100 nm, so dark pink color was observed. For the biosensing demonstration, Bovine serum albumin (BSA) and Anti-BSA bio-affinity interaction was measured using the self-assembly gold nanoisland LSPR sensor. Anti-BSA was functionalized onto the sensing site and BSA of known concentrations, i.e. 1 ug/ml was injected. The results showed LSPR spectral intensity change of 650 counts at the resonance slope of 634 nm. With standard deviation of spectral intensity fluctuation at 7 counts, the detection limit of BSA was estimated at about 0.5 nM which was comparable with that of LSPR systems with more elaborate nanostructures. The limit of detection of the present system can be further improved by implementing phase measurement and further nanostructure improvement.
Lead-free (Ba,Ca)(Zr,Ti)O3 Based Electrocaloric Devices: Challenges and Perspectives
Authors: Suchaneck Gunnar , Gerlach Gerald
Published: December 2013

In this work, we analyze the requirement to (Ba,Ca)(Zr,Ti)O3 thin films for applications in electrocaloric devices. We demonstrate that large temperature changes are realized mostly independent of the used material by applying sufficient electric fields. Ferroelectrics exhibiting a diffuse phase transition are beneficial for electrocaloric applications, but they change the range of operational temperatures.
Ab initio investigation of the structural and magnetic properties of Ni-Pt-Mn-Ga alloys
Authors: Zagrebin Mikhail A. , Sokolovskiy Vladimir V. , Buchelnikov Vasiliy D. , Entel Peter , Taskaev Sergey V.
Published: December 2013

Structural and magnetic properties of Ni2-xPtxMnGa alloys are investigated from first principles calculations with the help of the spin-polarized relativistic Korringa-Kohn-Rostoker and Plane-Wave Self-Consistent Field methods. The atomic chemical disorder at specific site has been implemented using coherent potential approximation. Calculated equilibrium lattice parameters are in a good agreement with experimental data and other theoretical calculations. The composition dependences of the magnetic exchange couplings and the Curie temperature for cubic phase are obtained. Our calculations have shown that an increase content of Pt results to decrease of magnetic interactions between Mn atoms and to change of interaction sign from ferromagnetic type to antiferromagnetic one for composition Ni1.0Pt1.0MnGa. Calculated Curie temperatures are in an agreement with experimental data.
Characterization of nano-crystalline structure of TiO2for Dye-sensitized Solar Cells by Raman spectroscopy and spectroscopic ellipsometry
Authors: Mamedov Sergey , Moriyama Takumi , Numata Tomoko , Nabatova-Gabain Nataliya , Yanagida Shozo , Yan Li
Published: December 2013

Dye-sensitized solar cells (DSSCs) are attractive alternatives to conventional solid-state photovoltaic devices because of performance, stability, environmental compatibility and cost. In contrast to the conventional systems where the semiconductor assumes both the task of light absorption and charge carrier transport, these two functions are separate in DSSC and, therefore, efficiency is very sensitive to the cell structure/composition. High-efficiency DSCs based on mesoporous nanocrystalline titanium dioxide (TiO2) electrodes have received considerable research attention in the past decade. Grain size and thickness of the mesoporous TiO2film have shown a dominant effect on the efficiency of the photovoltaic devices.

We have investigated screen printed TiO2films deposited on a textured fluorinated SnO2(FTO) glass substrate, using Raman spectroscopy and spectroscopic ellipsometry. Materials were prepared by repeating a same screen-printing procedure once, twice and three times, using TiO2paste with 10nm, 20 nm and 200nm particles sequentially. Raman spectra of PV devices cells taken at different excitation (266 nm, 325 nm, 364 nm, 532 nm, 633 nm, and 1064 nm) as well as pure TiO2oxides are presented. Different excitation wavelengths allow to probe different depth of the sample. It was found that there is strong correlation of the position and the width of E2gmode of anatase at 144 cm-1and size of TiO2particles. The samples show that this peak shifts to the high frequency region and becomes broader for small size particles. The position and broadening of the peak can be described by optical confinement model that depends on the size of nano-crystals. Results showed varying grain sizes as correlated with different TiO2paste applied. Thickness, optical constants and porosity of TiO2films were determined by spectroscopic ellipsometry. In this work, we have demonstrated the use of Raman Spectroscopy and Spectroscopic Ellipsometry for non-destructive characterization of nanocrystalline TiO2films for dye-sensitized solar cells.
Briefing: Sustainable urbanism, financial prudence and investment
Authors: Mentz Kobus , Goble Susannah
Published: December 2013

Sustainable urbanism is challenged by a move towards austerity. An alternative approach is required for local authorities trying to do more with less while maintaining a strategic approach. Financial prudence can be balanced with strategic objectives through a bottom-up, inside-out approach, which considers internal integration as well as external leverage opportunities to set the scene for a rigorous financial strategy. This creates a virtuous economic cycle. Engaging with elected officials to promote rational decision-making is essential to this process.
Water as a trophic currency in dryland food webs
Authors: Allen Daniel C , McCluney Kevin E , Elser Stephen R , Sabo John L
Published: December 2013

Water is essential for life on Earth, yet little is known about how water acts as a trophic currency, a unit of value in determining species interactions in terrestrial food webs. We tested the relative importance of groundwater and surface water in riparian food webs by manipulating their availability in dryland floodplains. Primary consumers (crickets) increased in abundance in response to added surface water and groundwater (contained in moist leaves), and predators (spiders and lizards) increased in abundance in response to added surface water, in spite of the presence of a river, an abundant water source. Moreover, the relative magnitude of organism responses to added water was greatest at the most arid site and lowest at the least arid site, mirroring cricket recruitment, which was greatest at the least arid site and lowest at the most arid site. These results suggest that water may be a key currency in terrestrial dryland food webs, which has important implications for predicting ecosystem responses to human‐ and climate‐related changes in hydrology and precipitation.
Advances in SCAL Data Interpretations on Multi-Scale Measurements from Different Carbonate Rock Types in a Giant Oilfield in Abu Dhabi
Authors: Dernaika Moustafa R. , El Din Samy Serag , Kalam Zubair , Hannon Loay
Published: December 2013

The evaluation of complex carbonate reservoirs is a challenging task for petrophysicists and reservoir engineers, and a detailed understanding of reservoir heterogeneity and its relation to wettability, fluid distribution and flow properties is still lacking.

In previous publications we investigated the effect of sample sizes on poroperm variations and cementation factors derived from resistivity measurements. Whole cores were essential in capturing representative data in heterogeneous carbonates. In this study the effect of static rock type and sample size (i.e. plugs versus whole cores) was investigated on SCAL data derived from capillary pressure and resistivity index experiments at reservoir temperature and net confining stress. The plugs and whole cores were initially selected according to static rock types comprising lithofacies classification and petrophysical grouping.

The obtained SCAL data from plugs and whole cores in each rock type grouping were studied in light of the initial static rock type. Data variations within the same rock type were detected among the plugs and between the plugs and the whole cores. Those variations were investigated in details to understand the degree of local heterogeneity and its effect on static and dynamic SCAL data. Data variations between the different static rock types were also investigated and assessed on the basis of dynamic imbibition data. Whole cores were generally found to yield different capillary pressure and saturation exponents that may not be possible to derive from average plug data. Those petrophysical variations will have large impact on reservoir rock types and saturation functions for optimum reservoir performance predictions.
Analytical Comparison of Emperical Two Phase IPR Correlations for Horizontal Oil Wells
Authors: Jabbar Muhammad Yousuf , AINuaim Sami
Published: December 2013

The concept of an Inflow Performance Relationship (IPR) has long been used to predict or estimate the relationship between pressure drop in the reservoir (drawdown) and well flowrates (production). Such relationships are used to monitor and optimize the producing life of a reservoir; and also for design calculations. Engineers often make use of the IPR to understand the deliverability of a reservoir, as well as to identify and resolve problems which may arise from the exploitation of a field.

The IPR concept provides an engineer with the means to determine the performance of a given well by relating inflow (flowrate) to the pressure condition in the well and reservoir at a given time. The most common application of the IPR concept is to consider the effects of different operational conditions on the pressure and flowrate profiles for a given well at conditions other than the initial condition.

Except Harris, the models reviewed in the literature were all following Vogel’s approach for two-phase vertical wells. This study consists of the innovative approach to regress the coefficients of Harrison Exponential equation. Hence a new correlation for the horizontal two phase IPR was proposed to estimate well performance.

The Comparison of the absolute error of the flow rate of available IPR correlations and the proposed correlations was done for statistical analysis. A field case study was also considered in the study and the absolute error calculated for proposed correlation was (0.5468%) which was again the lowest error as compared to the other correlations. The proposed IPR model works as well as the other models at the normal flow condition. It can be used to estimate horizontal well performance conveniently.
New Generation Intelligent Completion System Integrates DownHole Control with Monitoring in Multilateral Wells
Authors: Al-Mohanna Khalid S. , Jacob Suresh , Ma Larry , Shafiq Muhammad
Published: December 2013

This paper describes the design, planning, implementation details and field trial testing of a new generation integrated intelligent completion system in a trilateral well in a field in Saudi Arabia. The system consists of a flow control valve with a real time choke position sensor and annulus & tubing pressure/temperature measurements integrated as one compact piece. The integration facilitates faster deployment of the intelligent system while avoiding complexity and disruption risks that are inherent with conventional intelligent completions. Included in the description are equipment, design, installation procedures and best practices.

In the "D" field, the wells are mostly horizontal multilateral oil producers drilled in high Darcy "A" sand and "B" sand reservoirs. In the trial test well; the main challenges were well placement, geo steering to "B" sand, sand quality and thickness variance, drilling successfully through shale sections to TD, installing inflow control devices screens in the laterals, mitigating cross flow due to pressures differences, and water breakthrough deferral.

Saudi Aramco has installed numerous numbers of intelligent completions over the last 8 years. The main drivers for these completions are to balance the drawdown and rates from each lateral, prevent cross flow between laterals and choke back laterals with high water or gas inflow. The increased monitoring capabilities of the system presented in this paper will help in production optimization of the multilateral wells.

This compact integrated intelligent completion system provides: isolation, selective flow control or water shut off for each lateral, real time annulus and tubing P & T monitoring for each lateral, pressure build-up, interference testing between laterals, real time position sensor to confirm choke position, production optimization for each lateral, faster operation time due to fewer positions, enhanced reserve recovery, extended well life, reduced future intervention, and minimal production interruption.

Using variable positions flow control valve, water production can be managed to sustain longer oil production while minimizing water cut from laterals. Monitoring the flowing pressure in real time allows producing the well at optimum rate above the bubble point pressure.

Knowledge and lessons learned from this successful installation have provided an insight into this new generation integrated intelligent completion benefits and paved the road for further deployment for similar applications.
Results from First Campaign of Field Testing of Multiphase Flow Meters Conducted in Saudi Arabian Wet Gas-Condensate Producers
Authors: Rodriguez Ruben Villegas , Leal Jairo A. , Hussain Shahid , Atwi Mohammed , Ruwaished Azmi , Garzon Franciso O.
Published: December 2013

Proper testing and measuring of a gas-condensate well is essential to ascertain the state of the hydrocarbon system at reservoir conditions and to plan the best production and recovery program for the reservoir. At surface, the volumetric measurement of three phase flow of a wet gas well has been considered challenging. Existing conventional metering devices and ordinary multiphase flow meters (MPFMs) are usually incapable of providing accurate measurement of flow rates in a dominating high gas volume fraction. Portable separators equipped with liquid gauge tanks are still considered accurate, but are bulky and expensive.

This paper discusses the results obtained from tests conducted using multiphase flow meters in wet gas-condensate producers at a wide range of flowing conditions. The meters were installed in conjunction with a regular three-phase test separator, and the objective of the tests was to measure meter accuracy in comparison with the data obtained from the conventional test separator. Obtaining accurate three-phase data in wet gas producers poses a significant challenge for the majority of conventional multiphase flow meters, because of the high-gas volume fraction (95 % and above) nature of the wells. The paper also discusses some lessons learned, challenges and uncertainties associated with accurate flow measurement of a wet gas well encountered throughout the testing, as well as other important observations.

The tests were conducted by Saudi Aramco over a four-month period using two MPFMs (A and B) in five different wells, spread out throughout the Ghawar field.The tests were conducted in wells producing at rates ranging from 10 to 40 MMSCFD, and condensate-gas ratios ranging from 30 to 320 Bbls/MMSCFD. Three tests were conducted in each gas producer, totaling 15 tests. The testing concluded that both meters require technological upgrading to meet the acceptance criteria in measuring the three phase flow with acceptable accuracy.
Outstanding Well Construction Industrialization Bringing Tunu Field Production to New Perspectives
Authors: Oumer S. , Biyanni H. M. , Yudhia D. P. , Putra S. , Wibowo A.
Published: December 2013

The main challenge faced by TOTAL EP INDONESIE in the Mahakam delta is the relentless fight against the mature fields decline. The Oil & Gas industry commonly tackles this issue by implementing an enhanced hydrocarbon recovery plan and by increasing the number of wells brought to production. Tunu is a giant gas field discovered in 1977 and located in the Indonesian Mahakam delta, East Kalimantan. To support the field development and maintain the associated production, more than 850 wells have been drilled and completed for a cumulative gas production over 8.3 Tcf by end of 2012. This was possible thanks to the drastic well construction activity increase led since 2005. The rig units were the primary variable to increase the number of delivered wells. Up to seven rigs were operated in the Mahakam delta while implementing a sharp performance improvement methodology to postpone the production decline. In 2011, the highest number of wells ever delivered in the Mahakam (114 wells) was achieved with 5 rigs continuously in operations highlighting the success associated to the implemented well construction optimization.

Since the early beginning of the drilling operations on Tunu, a tremendous work has been done to reduce the overall well construction duration without jeopardizing the operations safety and the wells productivity. The fundamental concept developed to achieve our target was the "industrialization" of our overall well delivery process, the main leverages being the implementation of innovative well architectures, technology and the optimization of our operations using a statistical approach.

Today, the average well duration on Tunu field is around 15 days when in the early 80’s, 50 days were required to deliver a well! The success of our well construction performance improvement project lays in a tailored innovative methodology and the performance culture implemented within the entire team.
Appraising the Performance of Cyclic Production Scheme Through Reservoir Simulation, a Case Study
Authors: Al-Zahrani Tariq
Published: December 2013

Oil wells in mature fields usually produce high water rate exceeding 80% water cut. This in turn will increase capital investment for expansion of water handling facilities. Further, high water production may cause adverse effects on the reservoir performance which can result in production losses due to premature water coning and channeling.

To mitigate this situation, many strategies have been implemented in order to reduce water production, optimize oil production and revive dead wells and one of which is to do cyclic production scheme (CPS). This strategy enhances the sweep efficiency, pressure maintenance and reduces the water handling cost. CPS is an innovative concept to help mature fields to reduce water production and it requires alternatively shutting and flowing wells with high water cut over a predetermined time.

This simulation study assesses the effectiveness and the performance of CPS implemented in a reservoir simulation model of a matured oil field. Simulation runs with several scenarios were conducted to understand and optimize the impact of CPS. The simulation results provided the best cyclic production/shut-in period and showed significant advantages of applying CPS over the regular non-cyclic production in all scenarios. In this study, more than 93 wells have been evaluated and most of these wells showed good overall oil recovery after applying CPS strategy.
Renewable Energy at Kuwait Great Burgan Oil Field
Authors: Nayef Mazin
Published: December 2013

Renewable power generation can help countries meet their sustainable development goals through provision of access to clean, secure, reliable and affordable energy. This energy has gone mainstream, accounting for the majority of capacity additions in power generation today. Tens of Giga watts of wind, hydropower and solar photovoltaic capacity are installed worldwide every year in a renewable energy market that is worth more than a hundred billion USD annually. Other renewable power technology markets are also emerging. Recent years have seen dramatic reductions in renewable energy technologies’ costs as a result of R&D and accelerated deployment.

International Renewable Energy Agency (IRENA) Member Countries have asked for better, objective cost data for renewable energy technologies. This aims to serve the need and its part of a set of reports on wind, biomass, hydropower, concentrating solar power and solar photovoltaic that address the current costs of these key renewable power technology options. The reports provide valuable insights into the current state of deployment, types of technologies available and their costs and performance. The analysis is based on a range of data sources with the objective of developing a uniform dataset that supports comparison across technologies of different equipment, project and cost of electricity.

In 212 BC, Archimedes is said to have used mirrors for the first time to concentrate the power of the Sun’s rays. In 1615, Salomon De Caux invented a small "solar powered motor" which was the first recorded mechanical application of the Sun’s energy. His device consisted of glass lenses, a supporting frame and an airtight metal vessel containing water and air. It produced a small water jet when the air heated up and expanded during operation. In the 1860s, French mathematician, August Mouchet proposed an idea for solar powered steam engines. In the following two decades, he and his assistant, Abel Pifre, constructed the first solar powered engines and used them for a variety of applications.

During the 1970s, methods of producing electricity via the solar thermal cycle were investigated. The efforts resulted in the further development of the technology and, in 1991, the first commercial power plant with a capacity of 354 MW electricity, based upon the concentrated solar power concept, was built in California, USA. This plant was erected over an area of 7 km2 and feeds about 800 million kWh per year into the grid.
Production Network Modeling Challenges in a Giant Carbonate Reservoir
Authors: Al Sayari Saleh Ali , Nuimi Saber Mubarak , Misra Sanjay
Published: December 2013

A giant onshore field producing from multilayered undersaturated carbonate reservoir presents many challenges. The field is producing since early seventies supported with peripheral water injection leading to wide variation in reservoir pressure and water cuts. The field has been produced with the help of 6 gathering manifolds. The northern manifold presents additional challenges as this area is affected with asphaltenes deposition problems in production tubing and flow lines. Tubing obstruction due to asphaltenes adversely affects flow basides cause difficulty in lowering pressure gauges resulting into scarcity of pressure survey data. Additionally, some wells are operating on gas lift and a gas injection pilot is located on the western side leading to Gas Oil Ratio (GOR) variations. The horizontal wells completed in the low permeability layer tend to cease production as the water cut reaches >35%. Production allocation, optimization and de-bottlenecking become difficult in such a scenario. It was, therefore, decided to build a production network model as a tool to overcome such problems. This paper presents the process of preparing the production network model. Tuning PVT properties for the field is described with reference to pressure traverse correlations. Well model calibration with paucity of pressure survey data was achieved with good agreement with production history. Production from each well at different choke setting, water cut and reservoir pressure was estimated and compared with field data. Proper tubing size selection would allow stable flow in the tubing even at high water cut differing gas lift implementation for many years. Production network model is a necessary tool for production and reservoir engineers for optimization, de-bottlenecking and potential estimation.
Improving Reliability of Surface Safety Valves by Upgradation with Self Contained Hydraulic Retrofit for Sour Services
Authors: Al-Azmi Falah , Parikh Chirag A.
Published: December 2013

The Surface Safety Valves (SSVs) installed downstream of the well head were put in lock open condition for many of the flowing ESP wells at West Kuwait field of Kuwait Oil Company. This was done to prevent damage to ESPs (installed down hole) due to frequent faulty trips of these valves. In such operational scenario, the SSV was not performing its normal function for which it is designed for, that is, to act as a safety barrier against abnormal flow conditions. The SSV malfunction was attributed to contact of hydraulic oil with the flowing sour crude oil and resulting contamination from the suspended solids, asphaltene and wax present in the crude. A pilot trial was conducted to upgrade these SSVs with Self-contained hydraulic control system and to evaluate functioning of this control system in providing adequate hydraulic actuation control to the already installed surface safety valves. This up gradation of flow powered SSVs (actuators) with self-contained hydraulic control system provides a low cost solution for improving performance and reliability these SSVs without any need of replacing complete surface safety valve. It is possible to achieve almost 100% reliable performance by installing such retrofit.
Successful Asphaltene Cleanout Field Trial in on-shore Abu Dhabi Oil Fields
Authors: Misra Sanjay , Abdallah Dalia , Nuimi Saber
Published: December 2013

Two of the prominent on-shore fields in Abu Dhabi are facing asphaltene deposition in a number of their oil producing wells. Several studies were carried out to understand the reasons for asphaltene unstability in the crude in both fields to help develop the appropriate mitigation strategies. A summary of the findings will be presented in this paper, however, the focus will be on the efforts undertaken to improve the current asphaltene clean-out formulations that are being used in the field. These formulations are composed of a dispersant chemical mixed with diesel as a solvent in 20:80 ratio and are pumped with the use of a Coil Tubing Unit (CTU) in tandem with jet blaster. However, the success rate reported for such clean-up jobs was 40% on average. Hence lab testing was carried out on a number of new dispersants and other potential solvents to improve the efficiency of the clean-up operations. After testing a combination of 8 commercially available dispersants with 3 solvents: Diesel, light gasoline oil (LGO), heavy aromatic naphtha (HAN), it was clear that a mixture of HAN with 3 particular dispersants in a 90:10 ratio were many times more efficient than the currently used formulations. These top lab ranked formulations were then field trialed in 7 wells by bullheading only, soaking overnight and running a gauge cutter to prove accessibility and success of the clean-up job. The wells were found to be perfectly cleaned with 25% reduction in the chemical requirement and a major saving in terms of avoiding the use of CTU for the clean-up operation. Implementation of new formulations would affect multimillion dollar cost saving. The savings increase many fold when opportunity costs against the previous unsuccessful jobs is taken into account. Besides, valuable resources like CTU can be gainfully deployed elsewhere. Results of this field trial will have larger implications for ADCO in the future as the number for asphaltene affected wells is rising as a result of field maturity and implementation of Enhanced Oil Recovery (EOR) and Artificial Lift (AL).
Memory Pulsed Neutron Logging - Avoiding Production Shutdown Losses Caused by In-field Logistical Constraints
Authors: Bilbeisi Jawdat M. , Chaker Hicham Abu
Published: December 2013

Proactive reservoir management is key to extending the maximum sustainable production plateau and achieving high recovery factors from any asset. A crucial parameter to monitor over time is reservoir fluid saturation, which is normally addressed with Time-lapse Pulsed Neutron Log data acquisition campaigns. The increasing complexity of secondary and tertiary oil recovery schemes (miscible gas injection) has created an even greater dependency on saturation monitoring tools to better delineate fluid movement within the reservoir.

The offshore fields in the UAE are quite mature, with a large number of wells and all associated infrastructure. Reservoir saturation logging campaigns are made increasingly difficult due to resource limitations - winch boats for equipment movement, slickline units for Down Hole Safety Valve retrieval and Tubing checks as well as offshore living accommodation limitations are major factors, any of which can cause the halt of a rigless logging campaign.

Further to the above logistics factors, the production losses associated with such a campaign due to well shutdowns caused by logging units on WHT compound the problem, as they tend to interfere with production targets, further reducing the number of wells available for monitoring.

A new Memory Pulsed Neutron Logging service has successfully been introduced into the UAE, which avoids these field logistics issues and minimizes production losses caused by saturation data acquisition, without negatively affecting data quality. The successful implementation of the first worldwide Coiled tubing conveyed Memory Pulsed Neutron logging service has further saved the operator time and money in terms of operational efficiency. This paper is designed to highlight all aspects in terms of operations, data quality and positive impact on hydrocarbon production associated with rigless logging operations. Case histories will be used to illustrate the gains. Potential future developments and applications will also be discussed.
Asphaltene Precipitation from Crude Oils : How to Predict it and to Anticipate Treatment?
Authors: Passade-Boupat Nicolas , Zhou Honggang , Rondon-Gonzalez Marianna
Published: December 2013

The prediction of asphaltene precipitation is an important topic in petroleum industry. Reliable evaluation of the asphaltene stability requires representative samples and measurement using special high pressure equipment. Moreover, development project may involve many reservoirs with many different fluids. Even inside of a connected reservoir, the quality of the oil and the asphaltene can vary through a large scale and the investigation of each fluid in the representative conditions become very expensive and often impossible.

Many fast screening methods have been proposed so far. The De Boer’s diagram is one of the most useful methods. However, it takes into account only the properties of the hydrocarbon phase without any investigation on the asphaltene fraction : this method gives always pessimistic prediction of the risk of asphaltene precipitation. Other methods, colloidal instability index for example, are not consistent enough to be used for flow assurance issue.

Based on some relevant solubility properties of the asphaltene fractions, a new and easy way for screening asphaltene instability is proposed. Using PVT properties of the live oil and an easy asphaltene characterization procedure, this method allow limiting advanced investigation only to fluids which present a real risk of precipitation. The asphaltene characterization can be performed on dead oil samples.

If a precipitation risk is stated, additional tests, performed on pressurized representative samples or taking into account reorganization of asphaltenes from different fluids, will help to define the severity of the risk. For mitigation, a test set-up has been developed: it allows evaluating the efficiency of chemical additives to prevent plugging under flow conditions of fluids above the asphaltene precipitation threshold. Depending on the crude oil, the severity of the precipitation conditions, and the nature of the additive, the blocking of the capillary tube can be delayed or prevented.
Type Curves for Pressure Transient Analysis of Horizontal Wells in Shale Gas Reservoirs
Authors: Lee Sung Jun , Kim Tae Hong , Lee Kun Sang
Published: December 2013

Shale gas has been recently emerged as a potentially enormous resource. Even though significant progresses have been made in the past few years, there appears to be a lack of information regarding the characterization of shale gas formations. A major purpose of the study is to demonstrate how this issue may be addressed by pressure transient analysis for horizontal wells in shale gas reservoirs. Extensive numerical simulations were conducted to model transient pressure behavior of a horizontal well and apply the results to well test analysis in shale gas reservoirs. For the simulation of realistic reservoir flow processes, the model incorporates a number of important formation properties and nonlinear processes in shale gas reservoirs including effects of well vertical location and length, dual porosity/dual permeability model, Klinkenberg effect, non-Darcy flow behavior, and adsorption/desorption under reservoir flow condition in addition to skin effect. Results from numerical simulations for nonlinear gas flow provided various type curves in terms of dimensionless pseudopressure and time for transient pressure responses in horizontal production wells. Results from type-curve matching for synthetic pressure data in shale gas reservoirs demonstrate that the conventional analysis approach may still be applicable for analysis of shale gas reservoirs. The results were shown to be a useful tool for the quantitative analysis on the transient gas flow behavior and determination of formation properties.
Structural Controls of Fracture Corridors in Some Middle East Fields
Authors: Ozkaya Sait I.
Published: December 2013

Two main structural types can be distinguished in the oil fields of the Middle East. (i) Fields transected by regional strike slip faults (type I structures). (ii) Fields with local faults that are associated with and confined to anticlinal structures (type II structures). Type II structures are either (i) growth folds mostly bound by deep seated faults which were reactivated under transpression or (ii) product of structural inversion, during Late Cretaceous and Late Tertiary major tectonic events. The reactivated faults have usually very small lateral displacement and the structures have very gentle dips.

The characteristic fault fracture patterns of type II anticlines in the Middle East have two diagnostic aspects: (i) faults and fracture corridors have uniform strike oblique to anticlinal axis and (ii) they disappear away from the structural highs towards franks and away. These two characteristic aspects can be explained only by superposition of regional stress and local tension related to structural bending.

Stress superposition not only explains the diagnostic faults and fracture patterns of type II structures, but also account for several details such as higher degree of fracturing in doubly plunging structures and fracture density as a function of the angle between fold axis and maximum horizontal stress at the time of fracturing.

Fault reactivation and structural growth in discrete pulses seem to be prerequisite for the typical fault fracture corridor patterns of type II structures. In many of type II anticlines, the paleo-stress that generated fold-bound faults and fracture corridors is oblique to fold axes. This suggests folding and fracturing took place under transpression and is related to fold reactivation or structural inversion. In either case, existence of a pre-existing structural control is essential, such as regional wrench faults or deep seated basement weakness zones.
Fluvial Facies Analysis Using Gamma Ray Measurements and Outcrop Studies in the Mesri and its Tributary Kuej River in the Mainland Gujarat Region, India
Authors: Bhosle Balaji , Nayak Pravas , Kumar Vikash
Published: December 2013

Exposed outcrop sections were measured in the Mesri River and its tributary Kuej in the Mainland Gujarat region. The studied sections fall in the transition zone between uplands and pediments and thus can give important clues on the behavior of the river and its depositional regime. Mesri river is the first order tributary of the major Mahisagar River south of which lies the oil rich Cambay graban.

The present study includes detailed description of the section, graphic log of the measured section and outcrop total gamma ray measurements at an interval of 15cm. Onsite gamma ray has provided a ready reference for the fining upward cycles with their top and bottom bounding surfaces which is otherwise very difficult to pickup from the exposed section.

The high and low spikes within the fining upward sequences may indicate the sudden change in the channel velocities and thus in grain size. The variation in gamma count can be related to the compositional variations but in this case since the source rocks are similar throughout the drainage basin so the factor of compositional variations can be negated. Both the exposed sections show complex amalgamated fluvial channel fills with moderately to poorly developed flood plain deposits. Most of the deposits are thought to be results of braid and point bars. Various types of calcretes from soft friable to very hard nodular and ferromanganese nodules were commonly seen throughout the studied sections.

Most of the section is moderately to poorly pedogenised. Slabbed sections of the calcretes were studied to see the internal structures. The calcretes offered new insights on the prevailing climatic conditions during the formation of the entire set of deposits. Insitu gamma ray measurements proved useful in identifying the lithofacies variations.
Performance Evaluation and Laboratory Experimental Study on New Gel-Type Profile Control Agent
Authors: Wang Guang , Zhang Dong , Yin Daiyin , Su Yunhang , Ma Chunhua
Published: December 2013

Alkaline/Sufactant/Polymer(ASP) flooding is a new technology of enhanced oil recovery remarkably after polymer flooding. Part of the test blocks of ASP have entered into middle development phase, and achieved better effects of increasing oil and decreasing water. However, Severe heterogeneity of main oil layers leads three elements liquid fingering along the low-permeability reservoir position of every sedimentary units in thick oil reservoir. It causes the low pressure of injection wells, high polymer concentration of production wells and serious inefficient and ineffective circulation of three elements liquid. Research on profile control technology of ASP is promoted to control the increasing speed of polymer concentration of production wells, decrease the inefficient and ineffective circulation of three elements liquid and improve development effect of ASP flooding.

The current profile control agents such as typies of HPAM/Cr3+, HPAM/Al3+ and HPAM/Organic Phenolic cannot fit the alkali environment of ASP. This paper uses the method of contrast test and orthogonal design to recipe a new gel-type profile control agent which can resist the alkali environment.The content of evaluation include impact on the interfacial tension of ASP compound system, impact of the concentration of NaOH on the performance of new profile control agent and impact of slow-release formulation on gelled time. Using heterogeneous core model of flat plate of three layers, four injection and one production wells, the experiments of profile control are conducted in ASP flooding. The results show: adding 0.035 PV new profile agent in the middle of ASP flooding can improve 4.06% of recovery factor more than ASP flooding so that it has a good profile control effect.

The profile control technology for ASP presented in this paper has improved the effect of ASP to a great degree, and it is a promising tool for the successful application of ASP in Daqing oilfield.
Uncertainty Quantification of a Chemically Enhanced Oil Recovery Process: Applying the Probabilistic Collocation Method to a Surfactant-Polymer Flood
Authors: Alkhatib A. , King P.
Published: December 2013

Uncertainty in surfactant-polymer flooding is an important challenge to the wide scale implementation of this process. Any successful design of this enhanced oil recovery process will necessitate a good understanding of uncertainty. Thus it is essential to have the ability to quantify this uncertainty in an efficient manner. Monte Carlo Simulation is the traditional uncertainty quantification approach that is used for quantifying parametric uncertainty. However, the convergence of Monte Carlo simulation is relatively low requiring a large number of realizations to converge. This study proposes the use of the probabilistic collocation method in parametric uncertainty quantification for surfactant-polymer flooding using four synthetic reservoir models. Four sources of uncertainty were considered: the chemical flood residual oil saturation, surfactant and polymer adsorption and the polymer viscosity multiplier. The output parameter approximated is the recovery factor. The output metrics were the probability density function and the first two moments. These were compared with the results obtained from Monte Carlo simulation over a large number of realizations. Two methods for solving for the coefficients of the output parameter polynomial chaos expansion are compared: Gaussian quadrature and linear regression. The linear regression approach used two types of sampling: Gaussian quadrature nodes and Chebyshev derived nodes. In general, the probabilistic collocation method was applied successfully to quantify the uncertainty in the recovery factor. Applying the method using Gaussian quadrature produced more accurate results compared with using linear regression with quadrature nodes. Applying the method using linear regression with Chebyshev derived sampling also performed relatively well. Possible enhancements to improve the performance of the probabilistic collocation method were discussed. These enhancements include: improved sparse sampling, approximation order independent sampling and using arbitrary random input distribution that could be more representative of reality.