bluuebunny/crossref_metadata_2025 huggingface dataset:
Microfibrous Entrapped Catalysts for Low Temperature CO Oxidation
Authors: Punde Shirish S , Tatarchuk Bruce J
Published: January 2010

Low temperature CO oxidation is characterized by slow reaction kinetics and CO self-poisoning of the catalyst, which compete with each other. A platinum catalyst with ceria as a promoter supported on a high surface area silica support has been developed. The catalyst has a significant activity for CO oxidation even in the presence of moisture. The catalyst showed a significant increase in activity with decreasing particle size (η<0.95, even at 100μm), indicating a clear transport limitation.

In case of larger catalyst particles the diffusional resistances affect the reaction kinetics, leading to greater rates of CO self-poisoning causing deactivation of the catalysts. However, conventional packed bed of smaller particles poses problems such as high pressure drop, packing issues, bed channeling, flow maldistributions, and dead zones in the reactor bed, which result in poor inter-phase heat and mass transfer rates. Most of these problems are related to poor packaging of smaller particles, strongly suggesting the need for immobilization of small particles. A new class of micro-structured materials consisting of sorbents/catalysts entrapped in metal, ceramic, or polymer microfibers (MFES/MFEC) has been developed at Auburn University. These materials immobilize the small particles by sinter-locking them in fiber mesh. The immobilization of particles results in better heterogeneous contacting efficiency. Additional studies have shown that the high voidages and structural uniformity of the MFES lowered the flow maldistributions, eliminated the peaking flows between particles, and helped achieve better radial dispersion. Thus MFEC/MFES improved inter-phase transport rates.

The Pt-CeO2/SiO2 catalyst entrapped in metal microfibers demonstrated a significant improvement in CO conversion compared to a conventional packed bed configuration while maintaining a lower pressure drop. Further catalyst entrapment in metal microfibers minimized cold spots in the reactor bed due to better intra-phase heat transfer rate. Higher effective thermal conductivity of MFEC improved the activity of the catalyst, which was particularly visible at high CO concentration wherein the CO inhibition kinetics takes over. For example, MFEC with 1/3 rd of catalyst loading as that of packed bed of same particle size, outperformed packed bed configuration.

The catalysts were prepared by incipient wet impregnation. Surface characterization of catalysts was carried out using CO, H2, O2 chemisorption, O2 – H2 titration, N2 physisorption, powder XRD, and was correlated with catalytic activity.

This microfibrous entrapped catalyst demonstrated a great potential for low temperature CO oxidation. These MFEC can be used in air purification, emergency escape products, and as a cathode air filter for PEM fuel cells.
Structural, Morphological and Photoelectrochemical Behavior of Hematite Modified by 120 MeV Ag9+ Ions
Authors: Singh Aadesh P. , Kumari Saroj , Shrivastav Rohit , Dass Sahab , Satsangi Vibha R.
Published: January 2010

Nanostructured hematite thin film for photoelectrochemical (PEC) splitting of water has great potential in the design of low-cost, environmental friendly solar-hydrogen production. Presently, solar-to-hydrogen conversion efficiency of PEC cell using iron oxide is limited by its poor charge transport due to high recombination losses and mismatch of band edges position with the redox level of water. High energy heavy ion irradiation provides the researchers a new dimension to introduce the desired changes in the behaviour of the material, which largely influence their properties. In order to get efficient PEC system, spray-pyrolytically deposited nanostructured hematite thin films were modified by irradiating the samples with 120 MeV Ag9+ ions with fluences ranging from 5×1011 to 1×1013 ions/cm2. Irradiated samples exhibited a partial transition from the hematite to the magnetite phase and reduction in particle size as indicated by XRD and Raman analysis. SEM picture showed a decrease the thickness and porosity of the films after irradiation. These irradiated films, when used in PEC cell showed significantly higher photocurrent density than unirradiated α-Fe2O3.
Ion Beam Modification of Pt Electrocatalyst Nanoparticles for Polymer Electrolyte Membrane Fuel Cells
Authors: Yamaki Tetsuya , Yamamoto Shunya , Hakoda Teruyuki , Koshikawa Hiroshi
Published: January 2010

Platinum (Pt) nanoparticles were prepared on a glassy carbon plate by a sputtering method and then irradiated with proton (H+) beams at energies of 0.38 and 10 MeV at room temperature. Cyclic voltammetry in an aqueous 0.5 mol/dm3 H2SO4 solution suggested that the lower-energy beam irradiation enhanced the active surface area of the Pt nanoparticles, calculated from the coulombic charge for hydrogen desorption. Thus, the nanoparticles would be modified by H+ beam-induced electronic excitation so that they have higher surface activity. The mechanism of this irradiation effect seems to be rather complicated and is still unclear at present, but we may discuss it in relation to a change in the interfacial crystal structure during the irradiation.
The Surface Modification of Nanocrystals for Biological and Environmental Applications
Authors: Zhou Chunjiao , Rong Pengfei , Wang Wei , Zhang Wenjie , Wan Qiang , Zou Bingsuo
Published: January 2010

Superparamagnetic nanoparticles can find many applications in different fields with greener techniques. The Fe3O4 nanoparticles less than 10nm coated with humic acid were synthesized by a chemical co-precipitation technique with cheap and environmental friendly iron salts and humic acid. The as-synthesized products were highly soluble in water. The efficacy for liver Magnetic resonance imaging (MRI) contrast agent was investigated by using it to the live rat and tumor-bearing rabbit models, on a conventional clinical 1.5 T MRI facility. Moreover the Fe3O4 –HA composite used in the Methylene Blue adsorption in neutral aqueous solution was studied too with high efficiency. The experimental results showed that the humic acid coated Fe3O4 superparamagnetic nanoparticles were suitalbe not only for liver MRI contrast agent, but also as adsorbents for removal of cationic organic dyes from neutral water.
APCVD SiCxOy Deposition as Na Barrier Layers for TCO/Low-E Glass Coatings
Authors: Zhang Wei , Salagaj Tom , Jensen Christopher , Strobl Karlheinz , Davies Michael
Published: January 2010

We report on the experimental investigation of the use of Sixtron Advanced Materials Silane-free gas generation system to deposit a transparent SiCxOy Na-diffusion barrier and anti-reflection film (for subsequent TCO thin film coatings) onto glass sheets with an APCVD deposition process. SiCxOy thin films (50-250nm thickness) with a tunable index of 1.65-1.75 are currently being deposited by APCVD On-line float glass coating systems depositing Transparent Conductive Oxide (TCO) coatings (both for Low-E windows and for solar panel manufacturing applications these coatings typically have a refractive index of about 1.9) using, for example, gaseous Silane (SiH4), Propylene or Ethylene and Oxygen. Such a barrier film is critical for achieving high transparency through its anti-reflection properties having an intermediate index, i.e. close to the value of to achieve high conductivity for subsequent deposited TCO layers and to improve the longevity of the TCO coating performance through its Na-diffusion barrier properties. The Sixtron's Silane-free gas generation system uses a solid material as starting source that is safe for shipping by airand thus removes many of the safety and cost concerns involved with handling and exchanging of hazardous Silane gas cylinders at the thin film production site. A successful transfer of this alternative Si-precursor material to the proprietary CVDgCoat™ APCVD coating platform under development by CVD Equipment corporation would enable the manufacturing and operation of safer and lower cost On-line and Off-line APCVD thin film glass coating systems for the fast growing coated glass sheet market driven by the growing alternative energy demand for both energy saving and energy generation materials.
Fabrication of Porous SiC Sheets with Controlled Porosity from Waste Clutch Boards
Authors: Domi Yuya , Shimada Shiro
Published: January 2010

When clutch boards are fabricated as friction sheets in automatic transmission of motorcars, their useless fragments are disposed of. In this study, an effective reuse of their waste clutch boards will be proposed. Clutch boards are composed of diatomaceous earth, carbon powder/fiber and phenol resin. Excess carbon in carbonized clutch boards was reacted with SiO formed from Si and SiO2 at 1500 °C in Ar to produce porous SiC sheets (79% porosity). High temperature treatment at 1700-1900 °C in vacuum made it possible to control the pore size of SiC sheets, having a main pore diameter range of 10 to 20 μm.

SiC sheets with porosity (79% to <60%) were also fabricated by heating carbonized/impregnated sheets with phenol resin in SiO gas at 1500 °C. SiC sheets obtained by the repeated cycle of impregnation/decomposition of resin heating at 1700 °C gave a tensile strength of 19 MPa.

When Aluminum-tri-sec-butoxide (ASB) solution was impregnated into SiC sheets oxidized at 1000-1200 °C in air and heated at 1400-1500 °C in Ar, SiC-mullite composite sheets with porosity (77%) were produced.
Preparation and Properties of Infrared Transparent Condutive Thin Films
Authors: Wang Yiding , Li Li , Chen Junjing , Song Zhenyu , An Yupeng , Zhang Yu
Published: January 2010

This paper presents results for infrared transparent and conducting thin films based on In2O3. The films have been prepared by magnetrons sputtering equipment with different condition. Typical transmittance of 70%-80% with a film sheet resistance of 80-300Ω/□ in the 3.5-5.0μrn region has been achieved.

Optically transparent and electrically conductive semiconductor Oxide films have been extensively studied in recent years. Such films have been prepared by various methods. In general, these films have high visible transmittance, but are opaque in the IR wavelength range of 1-12μm IR transmission. The infrared transparent and electrically conductive thin films are useful in certain important applications. For example, these films can be use as antistatic coatings, and while permitting a reasonable transmission coefficient for IR. Another obvious application is to serve as the conducting electrode for various optical devices where good infrared transmission is important. So, it is important to research indium oxide base infrared (3-5 um) transparent conduction thin films.

It has been developed that preparation condition influence on properties of thin films. Such as the sputtering time, and pressure, and power, and the substrate temperature, had great influence on the crystal structure, optical and electrical properties of In2O3-based thin films.

The In2O3-based thin films obtained were characterized and analyzed by X-ray Diffractometer (XRD), Atomic Force Microscope (AFM), Vander Pauw Method and Fourier Transform Infrared Spectroscopy (FTIR).
ZnO Thin Film Surface Acoustic Wave based Lab-on-a-Chip
Authors: Luo Jack , Fu Yongqing Richard , Du Xiaoye , Lee Daesik , Maeng Sung , Flewitt Andrew , Milne Bill
Published: January 2010

Lab-on-a-chip (LOC) is one of the most important microsystem applications with promise for use in microanalysis, drug development, diagnosis of illness and diseases etc. LOC typically consists of two main components: microfluidics and sensors. Integration of microfluidics and sensors on a single chip can greatly enhance the efficiency of biochemical reactions and the sensitivity of detection, increase the reaction/detection speed, and reduce the potential cross-contamination, fabrication time and cost etc. However, the mechanisms generally used for microfluidics and sensors are different, making the integration of the two main components complicated and increases the cost of the systems. A lab-on-a-chip system based on a single surface acoustic wave (SAW) actuation mechanism is proposed. SAW devices were fabricated on nanocrystalline ZnO thin films deposited on Si substrates using sputtering. Coupling of acoustic waves into a liquid induces acoustic streaming and motion of droplets. A streaming velocity up to ˜5cm/s and droplet pumping speeds of ˜1cm/s were obtained. It was also found that a higher order mode wave, the Sezawa wave is more effective in streaming and transportation of microdroplets. The ZnO SAW sensor has been used for prostate antigen/antibody biorecognition systems, demonstrated the feasibility of using a single actuation mechanism for lab-on-a-chip applications.
Effect of Thin Aluminum Coatings on Structural Damping of Silicon Microresonators
Authors: Sosale Guruprasad , Prabhakar Sairam , Frechette Luc , Vengallatore Srikar
Published: January 2010

Quantifying the effects of thin metallic coatings on the damping factors of micro- and nanomechanical resonators is important for the design of high-performance devices for sensing and communications. This study presents experimental results for the increase in damping caused by aluminum films coated on cantilevered single-crystal silicon beams. The monolithic silicon beams (100 to 125 microns thick) can operate at the ultimate limits of dissipation established by thermoelastic damping with quality factors ranging from 104 to 105. However, coating these beams with 60 to 100 nm of aluminum can increase the damping by factors of three to five. These results provide guidelines for designing composite micromechanical resonators, and establish the foundation of a new approach for accurate measurement of internal friction in substrate-bonded thin films.
Micromachined Active Piezoelectric Structures for Applications above 600 °C
Authors: Sauerwald Jan , Richter Denny , Fritze Holger , Ansorge Erik , Schmidt Bertram
Published: January 2010

Miniaturized monolithic langasite structures are micromachined using local doping of lan-gasite and wet chemical etching. The diffusion coefficients of niobium, strontium and praseodymium in langasite are determined in order to control the preparation process and to obtain information about the stability of locally doped structures at elevated temperatures. A wet etching process based on phosphoric acid for langasite is developed and used to manufacture microstructured elements like planar and biconvex membranes as well as field emitter diodes. These elements are characterized with respect to their application relevant properties such as resonator quality factor and field emission current at temperatures of 600 °C and above.
Fourier Transform Infrared Spectroscopy Characterization of AlN Thin Films Grown on Sacrificial Silicon Oxide Layers via Metal Organic Vapor Phase Expitaxy
Authors: Kuchibhatla Sridhar , Rodak L.E. , Korakakis D
Published: January 2010

Aluminum Nitride (AlN) films were grown using Metal Organic Vapor Phase Epitaxy (MOVPE) techniques on Si (111) substrates patterned with SiOx stripes and the vibrational properties of these films were investigated by Fourier transform infrared (FTIR) techniques. The grown films contained a predominantly wurtzite AlN phase in addition to oxidized aluminum and mixed AlN phases. The AlN film on amorphous silicon oxide (SiOx) was prone to corrosion when subjected to wet etching in buffered hydrofluoric acid solution thereby changing the material properties of the AlN film on SiOx. The etching process significantly reduced the oxidized aluminum phase and mixed AlN phases.
The Vibrational Modes of Model Bulk Metallic Glasses
Authors: Derlet Peter M. , Maaß Robert , Löffler Jörg F.
Published: January 2010

Bulk metallic glasses exhibit confined low and high frequency vibrational properties resulting from the significant bon and topological disorder occuring at the atomic scale. The precise nature of the low frequency modes and how they are influenced by local atomic structure remains unclear. Using standard harmonic analysis, the current work investigates various aspects of the problem by diagonalizing the Hessian of atomistic samples derived from molecular dynamics simulations via a model binary Lennard Jones pair potential.
Preparation and solid state NMR characterization of phosphonates encapsulated in raw and organically modified SBA-15
Authors: Azais Thierry , Aiello Daniela , Testa Flaviano , Laurent Guillaume , Babonneau Florence
Published: January 2010

We present in this communication the preparation and the solid state NMR characterization of phenyl phosphonic acid encapsulated both in pure and aminopropyl-modified SBA-15 mesoporous silica materials. The 31P and 1H MAS studies revealed two radically different behaviors of the confined molecules. The included phosphonic acid in SBA-15 is submitted to a confinement effect that implies a weak interaction with the SiO2 surface and a relative mobility at room temperature. On the contrary, phenyl phosphonic acid molecules in the aminopropyl modified sample possess a strong interaction with the hybrid surface of the material. This finding is supported by a two dimensional double-quantum 1H experiment that revealed the close proximity between phenyl phosphonic acid and aminopropyl surface groups.
Molecular Simulation of Water Confined in Nanoporous Ca-silica
Authors: Bonnaud Patrick A , Coasne Benoît A , Pellenq Roland J-M
Published: January 2010

This paper reports on a molecular simulation study of the thermodynamics, structure and dynamics of water confined at ambient temperature in charged silica nanopores of a widthH= 10 and 20 Å. The adsorption isotherms for water resemble those observed for experimental samples; the adsorbed amount increases continuously in the multilayer adsorption regime until a jump occurs due to capillary condensation of the fluid within the pore. Strong layering of water in the vicinity of the silica surfaces is observed as marked density oscillations are seen up to 8 Å from the surface in the density profiles for confined water. Our results also indicate that the Ca2+counterions remain in a space close to the silica surface whatever the pore width and the adsorbed amount of water. For all pore sizes and adsorbed amounts, the self-diffusivity of confined water is lower than the bulk due to the strong hydrophilic nature of the pore surface. Our results also suggest that the self-diffusivity of confined water is sensitive to the adsorbed amount of water molecules.
Development of a Flexible Conductive Polymer Membrane on Electroactive Hydrogel Microfibers
Authors: Bassil Maria Joseph , Ibrahim Michael Ibrahim , Souaid Eddy , El Haj Moussa Georges , El Tahchi Mario Remond , Boiteux Gisèle , Davenas Joël , Lanceros-Mendez Senentxu , Farah Joseph K.
Published: January 2010

Conducting polymers and hydrogels are two classes of polymers that currently receive an increasing attention in the field of biomaterials, particularly for their application in the assembly of artificial muscles. In this paper we present the development of Polyacrylamide (PAAM) microfibers and polyaniline (PANI) - poly vinyl alcohol (PVA) conductive gel membrane.

The fabricated PAAM microfibers have diameters between 1 and 12μm depending on the preparation parameters. These microfibers respond instantaneously to 100mV electrical stimulation, which solves the problem of time response of the hydrogels. On the other hand, we showed that the inclusion of conducting chains within a crosslinked gel matrix allows combining the conductivity of the PANI with the mechanical flexibility of PVA in order to provide flexible gel membranes that can adhere to the PAAM microfibers to ensure their electrical stimulation.
Fiber-reinforced Hydogels for Soft Tissue Replacement
Authors: Agrawal Animesh , Calvert Paul
Published: January 2010

Synthetic hydrogels have poor mechanical properties that limit their use in load bearing applications. In contrast, biological hydrogels are tough and strong due to reinforcement with nano to micron size fibers. Our work is focused on designing new class of hydrogel assemblies based on fiber reinforced hydrogel composites. In analogy to the spinning of a spider web, a pultrusion system was developed to spin micron-diameter polymer fibers from solution in order to build predefined three dimensional patterned fiber-reinforced hydrogel structures. The gel chemistry is based on epoxy-amine crosslinking. We have formulated various epoxy-amine gels with swellability ranges from 0% to 1000% in water. The fibrous reinforcement affects the swelling and mechanical properties of the gel. For mechanical characterization flat punch probe indentation technique was performed. The effect of fiber density and extent of swelling on the reinforcement of epoxy matrix is investigated. Based on a better understanding of fiber reinforcement of gels, we hope to be able to design strong gels for biomedical devices and soft machines.
Developmental changes in antioxidant enzymatic defences against oxidative stress in sheep placentomes
Authors: Garrel Catherine , Fowler Paul A , Al-Gubory Kaïs H
Published: January 2010

Early pregnancy is susceptible to oxidative stress, and thus characterisation of antioxidant systems and pro- and anti-apoptotic pathways would improve understanding of placental development and function. We aimed, therefore, to determine the activities of the antioxidant enzymes, copper/zinc-superoxide dismutase (SOD1), manganese-SOD (SOD2), catalase (CAT), glutathione (GSH) peroxidase (GPX) and GSH reductase (GSR); and to quantify the expression of BAX and MCL1 proteins in relation to the developmental changes in antioxidant defences in sheep placentomes sampled on days 35, 55 and 80 of pregnancy. Placentome progesterone content was analyzed to determine steroidogenic capacity. Malondialdehyde (MDA) and protein carbonyl were quantified in placentomes as biomarkers of lipid peroxidation and protein damage respectively. Placentome tissues demonstrated significantly increased content of progesterone and MDA at day 80 of pregnancy and protein carbonyl as early as day 50 of pregnancy. Progesterone and MDA contents were not different between days 35 and 55 of pregnancy. While SOD1 and CAT activities did not alter significantly, SOD2 activity decreased from days 35 to 55. GPX activity increased from days 35 to 55 and increased further to day 80 of pregnancy. GSR activity increased from days 35 to 55 of pregnancy. BAX protein expression decreased, while MCL1 increased from days 35 to 55 and 80 of pregnancy. The increased GPX activity was associated with a decrease in the BAX/MCL1 protein expression ratio. Changes in the antioxidant enzymatic defences could be a part of placentome adaptation to reactive oxygen species-induced oxidative stress at specific early developmental stages of pregnancy.
Diminished diet-induced hyperglycemia and dyslipidemia and enhanced expression of PPARα and FGF21 in mice with hepatic ablation of brain-derived neurotropic factor
Authors: Teillon Sarah , Calderon German A , Rios Maribel
Published: January 2010

Brain-derived neurotropic factor (BDNF) mediates many aspects of neuronal function, and plays a chief role in the central regulation of energy balance. In the periphery, it is expressed in organs involved in energy, lipid, and glucose homeostasis, including the liver, but its role there remains unclear. Here, we describe studies examining the effect of selectively depleting hepatic BDNF. Liver-specific mutant mice exhibited normal food intake and body weights when fed standard chow or high-fat diets (HFDs). However, whereas HFD intake induced mild hyperglycemia and hyperinsulinemia in wild-types (WTs), liver-specific BDNF mutants were protected from these effects. Serum levels of cholesterol and triglycerides were also elevated in HFD-fed WTs, but they were normal or slightly increased in BDNF mutants. Furthermore, whereas WTs fed HFD exhibited elevated levels of circulating alanine aminotransferase and aspartate aminotransferase, BDNF mutant males fed a similar diet had a normal content of both enzymes. Molecular analysis indicated that the livers of BDNF mutants fed HFD contained elevated levels of peroxisome proliferator-activated receptor α (Pparα or Ppara as listed in the MGI Database) and fibroblast growth factor 21 (Fgf21) transcripts compared with WTs. This is a notable finding as this pathway has anti-diabetic and lipid clearance effects. Accordingly, genes involved in lipid and glucose handling and targets of PPARα and FGF21 were upregulated in the BDNF mutant livers. The collective data indicate that hepatic BDNF might facilitate the emergence of insulin resistance, dyslipidemia, and liver disease following HFD challenge by suppressing PPARα and FGF21.
Track displacement and energy loss in a railway embankment
Authors: Hendry M. , Hughes D. A. , Barbour L.
Published: January 2010

The mainline railway track between Dublin and Belfast was constructed during the 1850s, with substantial lengths of railway embankment constructed over soft, peaty soils. In recent years Northern Ireland Railways (NIR) has noticed that the sections of the railway track constructed on these peaty soils have been deteriorating at an increasing rate. Train speeds have been reduced in response to concerns that cyclic track displacements appear to be increasing over time in response to train loading. Track maintenance has also increased significantly. The research described in this paper was undertaken to quantify the response to cyclic train loading of two portions of this track founded on peaty soils. Track displacements were recorded using a sensor system specifically created for this project. The sensor consisted of a photosensitive array, mounted on the sleepers, and a laser, which was targeted onto the photosensitive array from a location outside the area of influence of train loading. Track deflections from 5 to 20 mm were measured under train speeds from near zero to over 120 km/h. The temporal variation in track displacement was used to calibrate an analytical (Winkler) model. This analysis suggests that the deformation of the embankment under train loading was not due to dynamic excitation but rather to static deformation of the poor-quality fill and soft foundation materials. As a consequence, the analytical model highlighted that train speed has limited effect on the magnitude of the deflection of the embankment within NIR operating speeds, but has the potential to significantly reduce the power lost to the damping within the embankment and subgrade.
Remedial Sand Consolidation: Case Study From Mahakam Delta, Indonesia
Authors: Chaloupka V. , Riyanto L. , Tran Q.-B. , Rayne A. , Kristanto T. , Haekal M.
Published: January 2010

Tunu and Tambora gas fields are located in the Mahakam river delta in the province of East Kalimantan, Indonesia. The fields consist of wet gas bearing sand bodies over a height of 13000 ft. The main producing zones are developed by intensive drilling with wells simply completed to allow a bottom up perforation strategy. The main objective is gas production from the deeper Main Zone layers. The shallow reservoirs prone to sand production are not primarily targeted. When sand production after additional perforation is observed, gas production is normally limited to maximum sand free rates or the wells are shut in to avoid damage to surface equipment.

Sand consolidation has been used as a sand control method since the 1940’s. However, it had never been attempted in operator’s fields in Indonesia. To author’s knowledge sand consolidation is not commonly used in South East Asia, in general. Unlike widely used conventional sand control methods this alternative method allows production from sand prone reservoirs while maintaining full wellbore access below treated zones.

The treatments presented in this paper were to validate sand consolidation as a viable sand control option in operator’s fields in the Mahakam Delta, utilizing new internally catalyzed epoxy consolidation fluid. The treatments were performed with 1.75’’ coil tubing and a packer. To date three Tunu/Tambora wells have been treated. The treated reservoirs have been producing without sand production after treatment. This paper describes candidate selection, job execution and treatment results.
The Technique of CO2 Anticorrosive in Daqing's Deep Gas Well
Authors: He Liu , Cunliang Gao
Published: January 2010

The oil tubes and casings' corrosion had been researched under high pressure, high temperature in the Daqing's deep gas well regions. This paper analyzed CO2 corrosion environment's feature and principle in the lab and on the deep gas well field to grasp the CO2 corrosion rules and develop optimizing evaluation for the various casing pipes and corrosion inhibitors in the deep gas well, had been finished optimizing the completion pipe string design and technique to be most reasonable economical. These techniques supported the anticorrosive scheme design for various CO2 deep gas wells, established the reasonable productivity and provided the integrated various economic rational CO2 anticorrosive technologies for the development of the Daqing's deep gas well regions.

All the drilled gas well which had the industrial natural gas in the Daqing's deep gas well regions were high temperature, high pressure characteristics, there were 41.3% gas well was serious corrosion which the CO2 partial pressure was more than 0.2MPa. At the beginning of exploratory development, mostly materials of gas wells' oil tubes and casing pipes were made of the common carbon steel, the CO2 corrosion was very serious on these oil tubes and casing pipes. Although the exploitation oil tubes and casing pipes were made of 13Cr alloy steels can obtain the better anticorrosive effect but the cost of these tubes and casing' price was very high which cost was 5 ~ 6 times to the ordinary carbon steel casing pipes. Use lower investment price with the anticorrosive infection to invent and create a corrosion inhibitor control technique of economic rationality and auxiliary project.
Managed Pressure Drilling in Rub Al-Khali Empty Desert: Case Study Sarah-Qasim Formations
Authors: Ekpe Joseph , Kompantsev Andrey , Al-Thuwaini Jamal , Bu-Khamseen Raid , Emad Mohammad
Published: January 2010

In this paper, attempts have been made to describe the experiences of 1.5 months of Managed Pressure Drilling (MPD) operations conducted in hard rock Formation in Rub Al-Khali, Eastern province of Saudi Arabia.

The implementation of this technology arose from the lessons learnt from previously drilled 2 exploratory wells that penetrated the tight gas sandstone Formations of Sarah and Qasim at a depth exceeding 17,000 ft, where the temperature and stress are extremely high at 350°F and 1.0 psi/ft respectively. As a result of these conditions, it is necessary in all cases to perform hydraulic fracturing to define fluid characteristics and evaluate production potential.

The extreme low porosity range of 2-10 % coupled with low permeability range of 0.01 – 0.26 mD and high fracture gradient interval of 0.9 – 1.0 psi/ft are the main challenges on these wells. Moreover, other challenges faced include drilling with high overbalance mud weight across the reservoir and high abbresivity of the formation rocks resulting in difficulty identifying potential gas bearing sands and slow drilling rate respectively.

As a part of the referenced exploratory activity in the 3rd quarter of 2008, LUKSAR was challenged to drill across the target reservoir with minimum formation damaged, balance mud weight and swift reaction in identifying suitable coring interval. Hence, in response to these challenges, an extensive study and well design/engineering were carried out in order to accommodate the utilization of Managed Pressure Drilling (MPD) across Sarah-Qasim sandstone Formation on wells LUK-08 and LUK-09.

This paper summarizes the well operation and in particular lessons learned during the first field application of Managed Pressure Drilling (MPD) in LUKSAR Exploration Campaign that resulted in significant improvement in well deliverability compared to previously drilled wells in Sarah-Qasim structure.
Formation Damage through Aqueous Phase Trapping In Gas Reservoirs
Authors: Paiaman Abouzar Mirzaei , Moghadasi J.. , Masihi M..
Published: January 2010

Aqueous phase trapping (APT) as a kind of mechanical formation damage can occur in porous medium when water based well bore fluids come into contact with a formation which exhibits sub-irreducible initial water saturation. Such type of formation damage commonly occurs during drilling using water based fluids in tight gas reservoirs and in depleted conditions in rich gas retrograde condensate reservoirs and is a major mechanism of damage in these reservoirs.

Evaluating reservoir's potential for APT is of great importance where the reservoir is susceptible to APT, since well productivity can be improved through proper evaluating and consequent attempts to reduce associated formation damage. This can be done using APT laboratory tests on reservoir rock samples. But, due to some restrictions, an alternative approach is followed which is use of predictive formulas. During the last fifteen years, number of formulas has been proposed to evaluate the reservoir's potential for APT.

In this paper a full procedure for evaluating and minimizing formation damage through APT is described. Different formulas used for evaluating the sensitivity of a suspect reservoir to APT are reviewed. A new formula for evaluation of gas reservoir's potential for APT is presented; CAPT or coefficient of APT. Using information of some gas reservoirs, the comparison is made between predictions made by different formulas. Comparisons show that CAPT predicts true gas reservoir's potential for APT and is more accurate than other formulas.
New Technique for Calculation of Well Deliverability in Gas Condensate Reservoir
Authors: Gerami S.. , Sadeghi A.. , Masihi M..
Published: January 2010

Well deliverability is an important issue in forecasting the performance of many gas condensate reservoirs. Condensate accumulation near the wellbore can cause a significant reduction in productivity, even in reservoirs where the fluid is very lean. Generally, the well deliverability is affected by two pressure-drop sources due to depletion and condensate buildup.

Recently Rapid spreadsheet tools have developed to evaluate the well performance using material balance equation for depletion and two-phase pseudo pressure integral for well inflow performance. Most of them account for the effects of negative inertia and positive coupling in the calculation of gas relative permeability.

This paper introduces a new method for calculation of the well productivity in gas condensate reservoirs. This method uses the concept of two-phase pseudo pressure integral without any need to estimate the radius of two-phase region. The average reservoir pressure is calculated by using a general material balance equation. The only data required for implementing this method is PVT data, relative permeability curves and table of well flowing pressure versus time.

The approach is validated by using a single-well fine grid compositional simulation of a hypothetical reservoir model over a typical range of gas condensate reservoir parameters. The results show a reasonable agreement between the fine grid and the proposed approach. The new technique can be encoded on a spreadsheet in order to forecast the gas condensate well performance very rapidly.
Tight Ultra-deep Gas Field Production Optimisation – Development Optimisation and CO2 Enhanced Gas Recovery Potential of the Schoenkirchen Uebertief Gas Field, Austria
Authors: Secklehner Severin , Arzmüller Gerhard , Clemens Torsten
Published: January 2010

The Schoenkirchen Uebertief gas field is situated in the Vienna Basin, a pull-apart basin east of Vienna in Austria. The field is located inside the Mesozoic Northern Calcareous Alps thrust belt which is buried at this location by 3000m Neogene basin fill sediments. The gas was trapped in a steeply inclined thrust unit which is enveloped by Early Tertiary intraorgenic sediments. The top of the structure was encountered at a depth of 5050 m and the original gas/water contact at 5780 m. The field was and still is invisible on seismic - hence the discovery was purely based on a geologic model that was derived from outcrop studies along the western basin margin.

The field consists of intensively fractured dolomite with 3.7 % porosity and low permeability of around 3 mD. The initial reservoir pressure was 598 bar and the field contained gas with a CO2 content of about 12 %. Gas Initially In Place (GIIP) was 20 Bm3. Production from the field commenced in 1969. Until 2008, 12.2 Bm3 of gas have been produced. By optimising the production system, the expected ultimate recovery factor is 88 %.

The field has been produced by three wells located at one end of the15 km long and only 2.2 km wide structure. The proximity of the field to CO2 sources (refinery) and the well design which accounted for the high CO2 content in the produced gas makes the field a good candidate for CO2 geological storage.

CO2 injection into the field far away from the producers to optimise sweep efficiency was studied by performing compositional simulation runs. The results indicate that about 1 % incremental gas of the GIIP could be recovered in addition to avoiding CO2 emissions of 37 million tons of CO2.
New High-Density Fracturing Fluid to Stimulate a High-Pressure, High-Temperature Tight-Gas Sandstone Producer Formation in Saudi Arabia
Authors: Sierra Leopoldo
Published: January 2010

Local and international companies are focused on an aggressive gas exploration campaign in tight high-pressure and high-temperature (HPHT) sandstone formations. In all of the current cases, the prospective HPHT tight-gas producing layers were discovered at depths below 20,000 ft where normally the stress and temperature are extremely high in addition to the very low reservoir permeability conditions. For HPHT tight-gas formations, fracture stimulation is a required step to define the reservoir fluid and evaluate productivity.

The extreme stress and temperature conditions are the main challenges of performing fracture stimulations in HPHT environments. In high-temperature conditions, fracturing fluids especially need to be stable, induce minimum damage, and have good proppant transport capabilities.

In HPHT tight-gas formations fracture stimulation (375°F and 1.1 psi/ft at 20,000 ft), where the temperature and stress conditions exceed existing fracturing fluids application limits, there are also limits from working pressure capability of the available pumping equipment. For this need, a new high-density fracturing fluid (HDFF) was introduced to the industry. Extensive laboratory evaluation was performed to design a new HDFF and to identify a regional supplier for the high-density brine (12.3 lb/gal) used as the base fluid to mix the new crosslinked fluid. The new fluid system was successfully mixed and pumped in the field, enabling the fracture stimulation treatment of a HPHT well at lower surface treating pressure, lower horsepower, safer working environment, and using conventional 15,000-psi rated fracturing equipment. Without having this new fracturing fluid the fracture stimulation treatment would require 20,000-psi rated equipment, which is not normally available in the area.

This paper summarizes the extensive fluid qualification testing, well conditions, and lessons learned from the first field applications of the new high density fracturing fluid system in Saudi Arabia.
Fluid Contact Determination in Tight Gas Reservoirs; Formation “B” Case Study, Sultanate of Oman
Authors: Abd_Elmoula Ibrahim , Hasani Said , Jahwari Sultan
Published: January 2010

The traditional methods for fluid contacts determination in deep seated tight gas reservoirs are very difficult. This is a result of the down hole environment toughness and the complex nature of the rock. In addition to that, most of the tight gas reservoirs have either no, or poorly defined water table.

This paper presents a systematic methodology to determine the proper fluid contacts and to define the movable and unmovable fluids in tight gas reservoirs. It is a comprehensive workflow which integrates core measured Mercury Injection capillary pressure (MICP) and log data measurements.

MICP measurements have been used to detect the irreducible water saturation (Swirr), which was then integrated with core porosity to create the Porosity-Swirr relationships. These relationships have been transformed into bound water volume log profile (Bvwirr) using the log porosity measurements. The gas water contact (GWC) has been located by following the irreducible water saturation (Swirr) and the calculated water saturation (Sw) log profile, and the separation between the bound water (Bvwirr) and the total water bulk volume (Bvw). The GWC is also defined using a synthetic resistivity log, R0 and the relative resistivity discriminator curve (RRD) derived from the simple Archie's equation and following the R0 and true formation resistivity log separation.

These techniques have been successfully applied on the “B” reservoir section of a major gas field to detect the true GWC and to prove the presence of movable fluids. The results were successfully calibrated by well test and production logging results.

As demonstrated in the field case discussed in this paper, the findings of this study have important implications for hydrocarbon maturation assessments, field reserves evaluation and consequently the field development strategy.
Deep Gas Potential of Onshore Bahrain Field
Authors: Bugti Muhammad Nawaz , Mukhtar Abdul Nabi , Gaviria William , Nimmagadda Shastri
Published: January 2010

Bahrain Island is surface expression of a large anticline at depth - the Awali Field. It is one of the oldest producing fields, since 1932, in Middle East. Known producing reservoirs are in Cretaceous and Jurassic. In 1980s, E & P companies in Middle East started looking further below known reservoirs and there was regional success in Paleozoic Unayzah and Khuff Formations, which opened up new exploration frontiers in deeper gas. By late 1980s recognition of Paleozoic petroleum system started in Middle East. Discoveries made in Devonian reservoirs in Bahrain, Saudi Arabia & Turkey; Ordovician reservoirs in Jordan, Carboniferous reservoirs in Syria, and Silurian & Ordovician reservoirs in Iraq.

Authors attempted examining and assessing 325 Sq Km of 3D seismic and 400 line km of 2D seismic data, with six deep wells. Considerable Paleozoic section is deposited at Awali field and the anticlinal structure continues well into it, thus forming a basis for exploring an entrapment potential as deep gas play. Horizons interpreted below, producing Khuff and Unayzah, have numerous potential structures and their associated reservoirs in Jubah, Jauf, Tawil, Ra'an, Hanadir and Saq formations. The potential source rocks, such as Qusaiba Shales, also lie within Paleozoic section. Jauf reservoir of Devonian age is found to be gas bearing, and it needs appraisal and development. Fault Trap play anticipated for Jauf and below reservoirs. Its analogue has proven successful on the flanks of Ghawar structure in Saudi Arabia. Seismic data interpretation suggests some stratigraphic truncations, in lower parts of Paleozoic section and on the flanks of its structure, which in turn create a stratigraphic play. Considering high potential of hydrocarbon accumulation in Paleozoic, further exploration efforts are needed and authors initially propose new seismic acquisition campaign specially designed for imaging deeper plays in Awali.
A Completions Roadmap to Shale-Play Development: A Review of Successful Approaches toward Shale-Play Stimulation in the Last Two Decades
Authors: Chong King Kwee , Grieser Bill , Jaripatke Omkar , Passman Andrea
Published: January 2010

Almost three decades have passed since the early exploration of the north Texas, Barnett Shale. The Barnett serves as an example study for the shale lifecycle. Operators in North America have used the Barnett-shale development as a roadmap for the exploration of new shale plays like the Marcellus, Haynesville, and Eagleford. Each new shale play is unique in nature with respect to geologic setting, lithology, and production mechanism. It is useful to have a defined strategy for the discovery, development, and decline phases of each individual shale play. The roadmap to shale well-completion designs should include the following key factors: Fracability: capability of the reservoir to be fracture stimulated effectivelyProducibility: capability of the completion plan to sustain commercial productionSustainability: capability of the field development to meet both economic and environmental constraints

This paper reviews the evolution and development of completion practices of the major USA shale reservoirs in the last two decades and presents a roadmap for effective completion practices for shale stimulation. The completion roadmap uses the history of 16,000 shale frac stages in the Barnett, Woodford, Haynesville, Antrim, and Marcellus shales. Following the map through specific decision points will alter the path for individual shales. These decision points will be influenced by geologic, geochemical, and geomechanical information gathered along the way. The path toward a commercially viable shale play from the early asset-evaluation phase to late asset maintenance-and-remediation phase evolves from a series of decision trees throughout the process.

Information presented in this paper provides a completion engineer with better understanding of the factors involved in shale-play stimulation and provides a methodical approach to select appropriate and optimum solutions that have evolved during the last two decades.
A Review of the Impact of the Use of Formate Brines on the Economics of Deep Gas Field Development Projects
Authors: Downs J.D.. D.
Published: January 2010

The technical difficulty of constructing deep gas wells makes them costly items on any operator's budget sheet. For this reason there is a powerful economic driver for the operator to use the best available well construction technologies that will deliver a deep gas well at lowest overall cost while ensuring that the well's connectivity to recoverable hydrocarbons is not impeded in any way. In 1995 Mobil was the first oil company to use formate brines as drill-in and completion fluids to improve the economics of deep gas field developments. Since then the formate brines have been used in more than 30 deep gas projects (amounting to at least 140 wells) by major oil companies such as Total, Statoil, BP and Saudi Aramco. These developments have included the deepest reservoir in the North Sea and the largest HPHT gas field in the world. This paper collates and categorises all of the statements relating to the performance of high-density formate brines in deep gas well constructions, as recorded in a number of white papers written by three long-term users of the brines. A review of these statements provides an insight into where and how the formate brines are delivering economic benefits in deep gas field developments. This analysis is complemented by a look at the production performance of two deep HPHT gas fields drilled and completed with formate brines in 2001/02. The cumulative hydrocarbon production from these fields is now already close to or exceeding 90% of estimated recoverable reserves. The weight of evidence, supported by the sustained demand for formate brines in these applications over a period of 14 years, suggests that the use of formates introduces economies and efficiencies into deep gas field developments that are a) worth more in value than the overall cost of owning or leasing the brine and b) more rewarding than those provided by alternative well construction fluids.