bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technological Improvements in Wells Drilled With a Pneumatic Fluid
Authors: Mellott J. 
Published: December 2007

Abstract
Most of the technological improvements seen in the drilling of wells with a "pneumatic fluid" (hereafter referred to as air) have come from the mining industry which is primarily associated with shallow large bore wells. The oil and gas industry has failed to make the same technological improvements in "air drilling" as compared to wells drilled with liquid systems. Air drilling has remained a "step child" and treated as an art rather than a science. One of the primary differences has been the failure to treat it as a integrated system like liquid drilling. In "air drilling" components are pieced together with little regard to other components.A air drilling system is actually more complex than a liquid one and requires more engineering to be successful. Because the pneumatic fluid is compressible there many improvements that can be made to manipulate downhole pressure and velocity which cannot be done in a liquid system. It is actually advantageous to divert a portion of the pneumatic fluid into the wellbore before it reaches the bit. However to do this with consistency and divert the proper volumes at the proper depth a Pneumatic Fluids Drilling Model must be utilized which is rarely done. This paper presents new technology which has been proven in theory and practice to improve air drilling performance. The technological improvements include a model which accurately demonstrates downhole pressures, velocities and kinetic energy throughout the system so that various drillstring and wellbore geometry as well as pneumatic fluid volumes can evaluated quickly. The model demonstrates the effects of diverting a portion of the pneumatic fluid into the wellbore above the bit. The paper also describes a new tool the "downhole air diverter" or DHAD) which is deployed in the drillstring that can accurately divert the optimum amount of pneumatic fluid based on model recommendations. As a result of using this new technology to manipulate bottom hole pressures at the bit the energy normally lost to friction can be used beneficially resulting in lower surface compression cost, less hole erosion, higher penetration rates, longer bit life and a higher percentage of wells reaching TD without converting to incompressible fluids.
This paper presents conclusive data from bottom hole pressure tests demonstrating that the surge effect (Venturi Effect) which is used at the surface to draw pneumatic fluids away from the wellhead can also be created downhole to lower annular bottom hole pressures. By lowering this bottom hole pressure more velocity is created with less air and less friction. Case studies are presented demonstrating how this technology has been used successfully in the field under various wellbore conditions resulting in higher penetration rates, improved wellbore stability, longer bit life and overall reduced drilling cost.
Use of Lightweight Solid Additives To Reduce the Weight of Drilling Fluid in the Riser
Authors: Cohen J. H. , Deskins G. 
Published: December 2007

Abstract
This paper describes the first phases of development of a drilling system for offshore wells based on the use of lightweight solid additives (LWSA) to reduce the density of drilling fluid within the riser above the seafloor. Equipment and procedures were tested to pump LWSA down to the bottom of the riser without damage, separate them from the mud after the fluid mixture returns to the surface, recycle LWSA for immediate re-use, as well as several other problems. Initial developments and tests are described that successfully addresses many of these issues.
In offshore wells, particularly in deep water, the problem of maintaining a safe range of mud weights is compounded by the additional pressure that drilling mud in the riser exerts on the formation. If the effective weight of mud in the riser can be reduced, the range of safe mud weights is effectively widened at the formation, resulting in fewer casing strings and safer operations. Mud with high concentrations of LWSA might be pumped down from the surface through special lines and then injected into the riser at the mud line. The mixture of mud and LWSA flowing up the riser then weighs less than pure mud.
LWSA were developed and tested as spheres produced from different materials including glass, composites, and epoxy resins. Tests showed that LWSA could withstand high pressures existing at the bottom of risers. LWSA were able to be separated from oilfield muds using conventional oilfield shale shakers and hydrocyclones. Muds with LWSA could be pumped with conventional mud pumps without excessive pressure losses. LWSA were recirculated many times with minimal breakage, demonstrating that they could survive in commercial operations.
Significant cost savings will be possible in drilling offshore wells if remaining problems with LWSA can be addressed. In addition to reducing the number of casing strings required, drilling with LWSA would reduce tension load requirements on the riser and mud storage requirements on the drilling vessel, which will reduce the size of drillships or increase depth capability of existing vessels.
An Algorithm for the Analysis of Shaly Gas Sands
Authors: Saldaña Miguel A. , O'Brien William J. , Brown Susan L. , Gobran Brian D. , Sanyal Subir K. 
Published: December 2007

ABSTRACT
This paper describes an approach for analysis of shaly sands and a program for TI-59 calculators based on the theory of the neutron-density crossplot. The program calculates porosity, flushed zone water saturation, and amounts of dispersed, laminar and structural shale. Also, formation water saturation is determined using three shale models. The most appropriate value can then be selected according to the relative amounts of the shale types.
Estimation of QV Profile in a Sedimentary Type Geothermal Reservoir
Authors: Ershaghi Iraj , Ghaemian Shahed 
Published: December 2007

ABSTRACT
In-situ determination of Qv (effective concentration of clay-exchange cations) of sedimentary rocks using geophysical well logs is discussed with application to geothermal reservoirs. A method is proposed based on the solution of equations relating formation rock and fluid properties and the conductivity of mud filtrate to the data obtained from S.P. (Spontaneous Potential) and resistivity logs.
The application of the proposed method to some wells in the Cerro Prieto Geothermal field in Mexico is discussed.
CO2 Injection as an Immiscible Application for Enhanced Recovery in Heavy Oil Reservoirs
Authors: Khatib Ala K. , Earlougher R. C. , Kantar Kutluyil 
Published: December 2007

ABSTRACT
Most field applications and pilot tests of CO2 injection are for miscible drive, and are therefore confined to light oil reservoirs. However, it has been known for decades that as CO2 dissolves in heavy oil, it swells the oil and reduces its viscosity. Core displacement tests in the fifties indicated that substantial additional recovery of heavy oil, and in some cases light oil, was possible with carbonated water. Until recently, unfavorable economics discouraged field application, and yet in 1976 a field project was commenced in southern Arkansas.
Two techniques have been field-tested. These are "huff-and-puff" CO2 injection for stimulation of the producing wells and either alternate or simultaneous injection of CO2 and water.
Both process mechanisms are discussed and are illustrated, where possible, by the results of field tests in the United States. These have been in sandstone reservoirs containing light oils and heavy oils. Several other pilot or field projects are in the planning stage. A planned field demonstration project of both processes, in different test areas of a fractured limestone reservoir (oil 9° - 15°) in Turkey, is summarized.
The possible range of candidate reservoirs is discussed, and general economic comparison with steam injection is given. The obvious candidates are heavy oil reservoirs that are too deep for current steam injection technology and economics.
Stimulation of the North Coles Levee Field with A Retarded HF-Acid
Authors: Hall Bobby E. , Tinnemeyer Art C. , Underwood Porter J. 
Published: December 2007

ABSTRACT
The North Coles Levee field is located in the San Joaquin Valley, approximately halfway between the cities of Bakersfield and Taft, California. Production, from the Stevens Sand, has significantly declined, partly due to migration and/or swelling of fines. Nine wells in this field have been acidized with the sequential hydrofluoric acid (SHF) system within the last twelve months.
Six of these treatments were termed successful with an average production increase of 2.8 for all nine wells.
Presented in this paper are reservoir characteristics, production history and production data on the North Coles Levee field.
Gas Hydrates in Oil Systems
Authors: Mohammadi A. H. , Ji H. , Burgass R. W. , Bashir A. , Tohidi B. 
Published: December 2007

Abstract
Extensive studies have been conducted on hydrate formation in gaseous systems; however, little information is available on hydrate risks in oil systems. This is partly due to difficulties in measuring the hydrate stability zone in oil systems, as well as problems associated with compositional representation of such systems. Furthermore, it is reported that hydrate formation pose less risks in oil systems than gas systems, partly due to the presence of natural inhibitors, formation of water in oil emulsions, and possibly oil wet pipeline walls. However, little is known of the nature and mechanism of the natural inhibition and the response of the system to an increase in the water cut.
In this communication, we present details of two experimental set-ups specifically designed to study the hydrate risks in oil systems. They include a visual high pressure kinetic rig for measuring the hydrate stability zone, crystal size, distribution and the rate of hydrate formation and dissociation, and a glass micromodel for visual observation of hydrate formation / dissociation in micro-scale. We report some of the recently obtained experimental results using the above experimental equipment. The results show that the existing techniques should be revisited for generating reliable data in oil system. We also demonstrate that proper characterization of the heavy end and taking into account the possibility of wax formation may play a role in improving the reliability of predictive techniques. The results provide better understanding and evaluation of risks associated with hydrate formation in pipelines carrying oil.
Predicting Oil Displacement By Thermal Methods
Authors: Moss Jon T. 
Published: December 2007

ABSTRACT
Oil displaced by heat fronts associated with Thermal Oil Recovery methods is calculated using a graphical correlation of three-phase permeability data. Previous investigations were based on the two-phase flow of steam and oil behind the heat front and hot water and oil ahead of the condensation front. In situ combustion displacement has not been adequately studied, except to some extent by numerical methods and laboratory experiments, due to the complexity of gas, oil and water three-phase flow. The solution developed herein combines fluid flow with Marx-Langen-heim heat loss to predict heat front velocity and oil displacement.
A Parallel Adaptive Finite Difference Algorithm for Reservoir Simulation
Authors: Hoang H. M. , Kleppe J. 
Published: December 2007

Abstract
Adaptive finite difference methods for problems arising in flow of porous medium applications are being considered. Such methods have proved useful for overcoming limitations of computational resources and improving the resolution of the numerical solutions to a wide range of problems. By local refinement of the computational mesh where need to improve the accuracy of solutions, yield better solution resolution than is possible with traditional fixed-grid approaches, representing more efficient use of computational resources.
In this paper, we present a parallel adaptive cell-centered finite difference algorithm for black-oil reservoir simulation models. This is an extension of the adaptive mesh refinement methodology first developed by Berger and Oliger (1984) for the hyperbolic problem.
The material in this paper is subdivided into three parts. First we explain the methodology and intricacies of adaptive finite difference scheme. Then we extend a finite differential cell-centered approximation discretization to a multilevel hierarchy of refined grids, and finally we are employing the algorithm on parallel computers.
Our algorithm is fully adaptive in time and space through the use of sub-cycling, in which finer grids are advanced at smaller time steps than coarser one. When coarse and fine grids reach the same advanced time level, they are synchronized to ensure that the global solution is conservative and satisfy the divergence constraint across all levels of refinement.
The results in this work show that the approach presented is robust, and stable, thus demonstrating the increased solution accuracy due to local refinement and reduced computing resource consumption.
A Hybrid Approach To Improve Reserve Estimates in Waterdrive Gas Reservoirs
Authors: Yildiz T. 
Published: December 2007

AbstractThe conventional reserve estimate methods for waterdrive reservoirs are well established. Typically, the techniques proposed by Havlena and Odeh and McEwen are used. In general, the reserves estimated from the Havlena-Odeh and McEwen procedures are not unique since the recorded historical production data is simultaneously solved for aquifer parameters and reserves. Normally, multiple combinations of reserves and aquifer parameters match the field data equally well. Hence, a range of reserves rather than a unique value is found. The upper and lower limits of the reserve range may vary several folds.To pick the best solution out of the multiple realizations, statistical parameters are calculated for all the matches. The solution with some minimum statistical indicator is considered to be the best solution. Among the statistical indicators suggested are the standard absolute relative error, normalized sums of squares of differences, standard deviation, normalized standard deviation, curvature, and coefficient of variation.The reserve estimate based on some minimum statistical indicator may not be reliable. The best reserve estimate corresponding to the minimum standard absolute relative error may differ from those corresponding to the minimum normalized standard deviation or the minimum coefficient of variation.In this paper, a hybrid approach making use of available methods is employed to narrow the reserve range estimates in waterdrive gas reservoirs.
Avantages linguistiques, scolaires et cognitifs de l'immersion française
Authors: Lazaruk Wally 
Published: December 2007

Abstract: A survey of research on French as a second language (FSL) education in Canada suggests that French immersion (FI) students enjoy significant linguistic, academic, and cognitive benefits. We organize our summary of the advantages of FI around these three themes, comparing students’ proficiency in French and English across various FI programs, and assessing their overall academic achievement. Our review shows that FI programs enable students to develop high levels of proficiency in both French and English, at no cost to their academic success. Cognitive research associates bilingualism with heightened mental flexibility and creative thinking skills, enhanced metalinguistic awareness, and greater communicative sensitivity. Because cognitive benefits are contingent on a bilingual learner's proficiency in both languages, it may be that FI programs, which promote heightened proficiency in both French and English, foster in their students an underlying cognitive advantage.
Design of an Antibiotic Delivery System Based on a Bioresorbable Bone Substitute
Authors: Vogt S. , Schnabelrauch M. , Weisser J. , Kautz A. R. , Büchner H. , Kühn K.‐D. 
Published: December 2007

AbstractIn the current study a new composite material comprising calcium sulphate, calcium carbonate, and tripalmitin was developed as a bioresorbable drug carrier for the local antibiotic therapy. Device fabrication can be simply performed by compression moulding of the components. The evaluated bone substitute material based on a calcium sulphate/calcium carbonate composite exhibits an excellent biocompatibility and a therapeutically useful release profile. It, therefore, represents a promising new antibiotic delivery system for the efficient prevention and treatment of bone infections.
Kinked Star‐Shaped Fluorene/ Triazatruxene Co‐oligomer Hybrids with Enhanced Functional Properties for High‐Performance, Solution‐Processed, Blue Organic Light‐Emitting Diodes
Authors: Lai W.‐Y. , He Q‐Y. , Zhu R. , Chen Q.‐Q. , Huang W. 
Published: December 2007

AbstractA novel series of kinked star‐shaped oligofluorene/triazatruxene hybrids are conveniently prepared via a powerful microwave‐enhanced multiple coupling methodology. Constructing kinked star‐shaped architectures can effectively suppress crystallization and aggregation. The resulting materials are highly amorphous, showing stable amorphous morphology against crystallization. A triazatruxene core endows the materials with elevated highest occupied molecular orbital (HOMO) levels that are well matched to the anode work function, leading to a significantly improved hole‐injection property. They hybrids are highly luminescent in both solution (quantum yield is 0.52–0.80) and the solid‐state (quantum yield is 0.45–0.76) with bright blue emission. Remarkably, solution‐processed devices displaying single‐layer electroluminescence (EL) based on these oligomers exhibit efficient blue EL and demonstrate striking color stability, almost unchanged with increasing driving voltage. The best device performance has a rather low turn‐on voltage (3.3 V) and a high device efficiency (2.16 % @ 2382 cd m–2) as well as a high brightness (7714 cd m–2 @ 10 V) with CIE coordinates of (0.16, 0.15); it shows remarkably better EL performance than devices based on linear oligofluorene or polyfluorene counterparts. The results prove that an oligomer with kinked star‐shaped architecture is extremely promising for efficient and stable blue EL. The reasons for the enhanced functional properties and the improved color stability are discussed in relation to the chemical structures and components.
Gold‐ vs. Platinum‐Catalyzed Polycyclizations by O‐Acyl Migration. Solvent‐Free Reactions
Authors: Moreau Xavier , Goddard Jean‐Philippe , Bernard Matthieu , Lemière Gilles , López‐Romero Juan Manuel , Mainetti Emily , Marion Nicolas , Mouriès Virginie , Thorimbert Serge , Fensterbank Louis , Malacria Max 
Published: December 2007

AbstractPolycyclic derivatives incorporating a cyclopropyl group have been efficiently synthesized from propargyl acetates using platinum(II), gold(I) and gold(III) catalysis. These reactions which are also viable for the preparation of medium‐sized rings, proceed with a complete diastereocontrol and can also be run in neat conditions.
Selectivity of Rhodium‐Catalyzed Hydroformylation of 1‐Octene during Batch and Semi‐Batch Reaction using Trifluoromethyl‐Substituted Ligands
Authors: Koeken Ard C. J. , van Vliet Michiel C. A. , van den Broeke Leo J. P. , Deelman Berth‐Jan , Keurentjes Jos T. F. 
Published: December 2007

AbstractThe regioselectivity of catalysts generated in situ from dicarbonyl rhodium(I)(2,4‐pentanedione) and trifluoromethyl‐substituted triphenylphosphine ligands has been evaluated during the hydroformylation of 1‐octene. The influence of batch or semi‐batch operation, the solvent, and the number of trifluoromethyl substituents has been investigated. During batch operation in a supercritical carbon dioxide (CO2)‐rich system the differential n:iso ratio increases from approximately 4 to a value of 12–16 at about 90–95 % conversion for the catalyst based on bis[3,5‐bis(trifluoromethyl)phenyl]phenylphosphine. For semi‐batch conditions using hexane a constant n:iso ratio is obtained over a broad conversion range. Batch hydroformylation in neat 1‐octene is faster than in a supercritical CO2‐rich, one‐phase system, with a similar overall selectivity as observed in the supercritical case. The results provide further directions for the development of ligands that are especially designed for the separation of homogeneous catalysts in continuously operated hydroformylation in scCO2.
Investigation of molecular structure of bombesin and its modified analogues nonadsorbed and adsorbed on electrochemically roughened silver surface
Authors: Podstawka Edyta 
Published: December 2007

AbstractThis work describes the molecular structure of bombesin (BN) and its analogs on the basis of the absorption infrared and Raman results described below. In these analogues is replaced one ([D‐Phe12]BN, [Tyr4]BN, and [Lys3]BN) or two ([Tyr4,D‐Phe12]BN, [D‐Phe12,Leu14]BN, and [Leu13‐®‐Leu14]BN) amino acid residues within the peptide chain with a synthetic amino acid, creating antagonists to bombesin, which are useful in the treatment of cancer. It is also used surface enhanced Raman scattering (SERS) to study the differences and changes in the vibrational spectra of BN and its analogs, which were attached to an electrochemically roughened silver surface as these peptides interacted with target proteins. This work explores the use of SERS for molecules anchored to a macroscopic silver surface to interrogate the interaction of these peptides with protein receptors. The results presented here show that all peptides coordinate to the macroscopic silver surface through an indole ring and the methylene group of Trp8, the CO fragment, and an amide bond; however, the orientation of these fragments on the electrochemically roughened silver surface and the strength of the interactions with this surface is slightly different for each peptide. For example, the interaction of CH2 of [D‐Phe12]BN, [Tyr4,D‐Phe12]BN, [D‐Phe12,Leu14]BN, [Leu13‐®‐Leu14]BN, and [Lys3]BN with the silver surface perturbed the vertical orientation of the Trp8 indole ring on this surface. Hence, the indole ring adopted a close to perpendicular orientation on the silver surface for BN and [Tyr4]BN, only. © 2007 Wiley Periodicals, Inc. Biopolymers 89: 506–521, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Force spectroscopy of the fibrin(ogen)–fibrinogen interaction
Authors: Chtcheglova Lilia A. , Haeberli André , Dietler Giovanni 
Published: December 2007

AbstractFibrin aggregation is of vital importance in many physiological and pathological processes, such as blood coagulation, wound healing, and thrombosis. In the present study, we investigated the forces involved in the initial steps of the fibrinogen fibrin aggregation by force spectroscopy using the atomic force microscope. Our data confirm the existence of strong specific interactions between fibrin and fibrin(ogen), with unbinding forces ranging from 290 to 375 pN and a logarithmic dependence on the loading rate between 0.8 and 23 nN/s. © 2007 Wiley Periodicals, Inc. Biopolymers 89: 292–301, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com