bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of bioethanol as an alternative fuel on the emissions reduction characteristics and combustion stability in a spark ignition engine
Authors: Yoon S H , Ha S Y , Roh H G , Lee C S 
Published: April 2009

An experimental investigation was performed on the combustion performance, reduction characteristics of exhaust emissions, and engine performance of a spark ignition engine fuelled with bioethanol, ethanol—gasoline blend, and gasoline fuel. The test fuels were an ethanol—gasoline blend (E85), which consists of 85 vol% bioethanol and 15vol% gasoline, pure bioethanol (E100), and gasoline fuel without any additives (G100). In this work, the combustion and exhaust emission characteristics, including the combustion pressure, brake mean effective pressure (BMEP), and maximum brake torque (MBT) timing of the ethanol—gasoline blend and pure ethanol, were compared with those obtained with gasoline fuel. For the comparison of combustion and emissions characteristics for bioethanol, ethanol blends, and gasoline, the experiments were carried out under various engine operating conditions and the results were compared with those obtained using conventional gasoline fuel. The results of this study showed that an ethanol-blended fuel or pure ethanol led to a drastic decrease in exhaust emissions under all operating conditions. The exhaust emissions such as hydrocarbons, carbon monoxide, and nitrogen oxides were reduced when using the bioethanol-blended and undiluted ethanol fuel because of the highly oxygenated component of ethanol fuel. Because the ignition timing was advanced above MBT timing when the ethanol fuels were used, improved combustion stability and a better combustion phase were measured because of the high octane rating of the ethanol. Combustion performance such as the brake torque and BMEP remained nearly the same or increased over those found using conventional gasoline fuel under various spark ignition timings and throttle valve openings.
Tight Bounds for Permutation Flow Shop Scheduling
Authors: Nagarajan Viswanath , Sviridenko Maxim 
Published: April 2009

In flow shop scheduling there are m machines and n jobs, such that every job has to be processed on the machines in the fixed order 1,…,m. In the permutation flow shop problem, it is also required that each machine process the set of all jobs in the same order. Formally, given n jobs along with their processing times on each machine, the goal is to compute a single permutation of the jobs σ: [n] → [n] that minimizes the maximum job completion time (makespan) of the schedule resulting from σ. The previously best known approximation guarantee for this problem was O((m log m)1/2) [Sviridenko, M. 2004. A note on permutation flow shop problem. Ann. Oper. Res. 129 247–252]. In this paper, we obtain an improved O(min{m1/2,n1/2}) approximation algorithm for the permutation flow shop scheduling problem, by finding a connection between the scheduling problem and the longest increasing subsequence problem. Our approximation ratio is relative to the lower bounds of maximum job length and maximum machine load, and is the best possible such result. This also resolves an open question from Potts et al. [Potts, C., D. Shmoys, D. Williamson. 1991. Permutation vs. nonpermutation flow shop schedules. Oper. Res. Lett. 10 281–284], by algorithmically matching the gap between permutation and nonpermutation schedules. We also consider the weighted completion time objective for the permutation flow shop scheduling problem. Using a natural linear programming relaxation and our algorithm for the makespan objective, we obtain an O(min{m1/2,n1/2}) approximation algorithm for minimizing the total weighted completion time, improving on the previously best known guarantee of εm for any constant ε > 0 [Smutnicki, C. 1998. Some results of the worst-case analysis for flow shop scheduling. Eur. J. Oper. Res. 109 66–87]. We give a matching lower bound on the integrality gap of our linear programming relaxation.
Bromide-ion distribution in the interlayer of the layered double hydroxides of Zn and Al: Observation of positional disorder
Authors: Prasanna S. V. , Radha A. V. , Kamath P. V. , Kannan S. 
Published: April 2009

AbstractBecause of the anisotropy in bonding, layered hydroxides crystallize with extensive structural disorder due to the incorporation of stacking faults. In contrast, the loss of crystallinity in Br−-ion intercalated layered double hydroxides (LDHs) arises due to the positional disorder of Br− in the interlayer. The structure of the interlayer in other LDHs is poorly understood due to the low X-ray scattering power of the commonly found anions such as Cl− and NO3−\$\end{document} relative to that of the metal hydroxide layers. On heating to 175°C, the Br− ion migrates from positions of lesser site degeneracy to those of greater site degeneracy as dehydration of the interlayer opens up access to positions hitherto occupied by intercalated water molecules. The new (18h) site is situated closer to the proton of the metal hydroxide layer (1.809 Å) compared to the 6c site (2.402 Å). This shows a pre-association of the bromide ion with the proton of the hydroxide layer leading to the release of HBr upon decomposition of the bromide-containing LDHs. The fact that Cl−-containing LDHs also decompose with the evolution of HCl shows that such a redistribution of the atoms in the interlayer is more common than is generally recognized.
Biology and taxonomic identity of Erythroglossum
lusitanicum (Delesseriaceae, Rhodophyta) from the Iberian Peninsula
Authors: Díaz Pilar , Berecibar Estibaliz , Bárbara Ignacio , Cremades Javier , Santos Rui 
Published: April 2009

Abstract

Erythroglossum lusitanicum was originally described from sterile and tetrasporophytic material. The apical organization and the sexual structures have considerable relevance for classification of Delesseriaceae, and these are described here for the first time in this species. The range of morphological variability in some species of the genus Erythroglossum in Atlantic Europe has been broadened, requiring a revision of the taxonomic identity of E. lusitanicum. Reproductive characters observed in E. lusitanicum include: 1) procarps scattered over the blade surface and composed of a supporting cell bearing two 4-celled carpogonial branches and a single group of sterile cells; 2) carposporangia formed in chains; and 3) spermatangial sori consisting of two layers of spermatangial mother cells bearing spermatangia. These features, together with the Phycodrys-type apical organization, are in accordance with those described for the genus Erythroglossum. The main taxonomic features of E. lusitanicum that distinguish it from congeners in Atlantic Europe are thallus growth that occurs in each blade by means of a single apical cell located in the tip, and its turf forming habit.
Prediction of Wellbore Temperature Profiles During Heavy Oil Production Assisted With Light Oil
Authors: Yu Yanmin , Lin Tao , Xie Hongxing , Guan Yanyan , Li Kewen 
Published: April 2009

Abstract
In some heavy oilfields, oil can flow in the reservoirs but may not flow through the wellbore without taking measures such as heating or diluting with light oil because of the high viscosity caused by low temperature around the wellbore close to surface. We focused on the latter issue in this study which is being widely used in Tah oilfield and other oilfields in China. Since the viscosity of the crude oil changes with temperature significantly, accurate prediction of wellbore temperature profiles is of great importance to determine the injection rate and temperature of light oil for dilution. An analytical model was derived to predict the wellbore temperature profiles for the heavy oil production assisted with the addition of light oil from the annulus. The model was based on energy balance between the formation and fluids flowing through each conduit. The temperature profiles were calculated using the proposed temperature model and the results were compared with the measured data. Sensitivity analysis was conducted using the proposed model and the main factors that influence the temperature profiles were discussed.
Effects of Friction on Post Buckling Behavior and Axial Load Transferring of Pipe in a Horizontal Well
Authors: Gao Guohua , Miska Stefan 
Published: April 2009

Abstract
In this paper, the buckling equation and natural boundary conditions are derived with the aid of calculus of variations. The natural and geometric boundary conditions are used to determine the proper solution that represents the post-buckling configuration. Effects of friction and boundary conditions on the critical load of helical buckling are investigated. Theoretical results show that the effect of boundary conditions on helical buckling becomes negligible for a long pipe with dimensionless length greater than 5π. Velocity analysis shows that lateral velocity approaches infinity and lateral friction becomes dominant at the instant of buckling initiation. Thus, friction can significantly increase the critical load of helical buckling. However, once buckling is initiated, axial velocity becomes dominant again, and lateral friction becomes negligible for post-buckling behavior and axial load transfer analysis. Consequently, it is possible to seek an analytical solution for the buckling equation. To verify the proposed model and analytical results, the authors also conducted experimental studies. Experimental results support the proposed solutions.
Production Enhancement through Pattern Modification—Analysis and Field Results
Authors: Pu Hui , Wang Guofeng , Han Guangzhi , Base Casper 
Published: April 2009

Abstract
Xinzhao oilfield, a naturally fractured low-permeability field in Daqing, was put into development in 2000 using an inverted nine-spot waterflood pattern with 300m×300m well spacing. Although waterflooding at Xinzhao oilfield had been an economic success, performance had generally been considered disappointing because oil response following expansion and waterflood adjustment was always less than predicted, so an integrated study aiming to improving the development effect of Xinzhao oilfield was conducted. This paper presents the results of a study addressing the impact of fractures on the recovery and on the reservoir management in pattern waterfloods.
Geological study and reservoir performance study indicate that several factors result in this seemingly unfavorable performance, one of main reasons are that the inverted nine-spot pattern is not compatible with the orientation of fractures. The production wells on the row of injectors are seriously watered-out and watercut increases very fast. Reservoir simulation studies indicate that oil cut can be improved if the injection pattern is modified from current inverted nine-spot well pattern to direct line drive pattern to take advantage of orientation of fractures. A field test project based on these studies has yielded results that indicate improved economic performance and better development effect.
Predicting Production Outcome from Multi-stage, Horizontal Barnett Completions
Authors: Grieser Bill , Shelley Bob , Soliman Mohamed 
Published: April 2009

Abstract
Developing a predictive reservoir model involves determination or estimation of key reservoir components, which can vary through the rock volume. Sophisticated, 3-D grid models usually require significant input data and are built for conventional reservoirs producing in Darcy flow.
Production from the Barnett shale is not conventional. Shale-rock gas flow involves a complex mixture of free and adsorbed storage and production mechanisms. Free gas can be stored in the microporosity, natural fractures, or thin lamination existing or created during hydraulic fracturing. Adsorbed gas is contained in the organic material randomly distributed in the bulk rock.
Horizontal, multistage-fractured wellbores add another level of complexity. Massive hydraulic fracturing of horizontal shale has shown complex fracture networks are created along the wellbore. Mapped data suggests multiple fracture planes are created during injection. These fracture planes can be irregular in length and are not always symmetrical. Conventional reservoir models can not handle this level of complexity.
A new, 3-D, four-phase, nonisothermal, multiwell black oil and "Pseudo-compositional" simulator that allows placement of multiple transverse fractures along the horizontal has been developed. Its ability to model horizontal, multiwing, transverse fractures and account for all three reservoir phases, including injected fluid, makes this model more predictive of production.
This paper uses mapped fracture dimensions of horizontal wells in the north Texas Barnett (NTB) to build a reservoir model. Comparisons of model production to real production are made to demonstrate the model's predictive ability.
Evaluation of Twophase Flow Correlations and Mechanistic Models for Pipelines at Horizontal and Inclined Upward Flow
Authors: Yuan Hong , Zhou Desheng 
Published: April 2009

Abstract
In this study, commonly used two-phase flow pressure prediction correlations and mechanistic models for pipelines in petroleum industry are evaluated against experimental data. The experimental data were obtained from published papers.
Horizontal and upward two-phase flow are common in oil and gas production and transportation. During pipeline design and simulation, experimental data are usually unavailable to calibrate against correlations and models. In this situation, it is difficult to determine which correlation or model to use in predicting pressure gradient in pipelines.
Experimental data used in this study are from Kokal and Stanislav papers (Kokal and Stanislav, 1989) and from Chen et al. paper (Chen et al., 1997). For the Kokal and Stanislav papers, experimental data were gathered from 1-inch, 2-inch and 3- inch pipes with seven inclination angles. Oil and air were used as testing fluids. During the experiment, superficial liquid velocities range from 1.2 to 10 ft/s and superficial gas velocities range from 0.76 to 85 ft/s. For the Chen et al. paper, data were gathered from a 3-inch horizontal pipe at stratified-wavy flow. Kerosene and air were testing fluids.
Beggs-Brill, Dukler-Eaton-Flanigan, Dukler and Eaton correlations and Xiao mechanistic model are evaluated in this study.
The results of this study can be used as guidelines in choosing two-phase flow pressure prediction correlations and models in designing and analyzing horizontal and upward two-phase flow pipelines.
Developing a 2 Year Oil and Gas Education Program
Authors: Bjornen K. H. , Stacy J. R. 
Published: April 2009

Abstract
Since the peak of employment in the domestic oil and gas industry in 1982, employment in this industry has declined by 51% from 708,000 to 345,000 workers in 2007. Prices for oil and natural gas have generally increased since 2000 with increasing worldwide demand. While the state of hiring for professionals and engineers is well known, there has also been a critical shortage of qualified field personnel who drill for and extract the oil and gas. In some regions this has led to limits on the growth of domestic drilling and production. Safety and environmental records have also been impacted due to the lack of experienced operators and well trained new hires. Additionally, the level of skills required for field personnel has increased due to technological advances in the oil and gas industry.
To address this need there has been an effort by some two year post secondary institutions to develop programs that will lead to well prepared entry level employees. The following paper will discuss curriculum development for a two year program offered through a community college. The program was designed such that graduates would have a broad background suitable for many facets of field work in the oil and gas industry.
Correlating Flowing Time and Condition for Perforation Plugging by Suspended Particles
Authors: Tran Tung V. , Civan Faruk , Robb Ian 
Published: April 2009

Abstract
Conditions leading to plugging of perforations in wells and pore-throats in porous formations are investigated experimentally. Accurate correlations are developed for the effect of pore-throat-to-particle-size ratio on flowing fluid conditions and plugging time leading to particle bridging. It is demonstrated that the critical pore-throat-to-particle-size ratio vs. particle-volume- fraction Reynolds number can be correlated satisfactorily using an exponential function and the dimensionless plugging time vs. reciprocal-particle-volume-fraction yields an exponential-type correlation. Such empirical correlations can be used to determine and alleviate the conditions which induce perforation and pore plugging by migrating particles in petroleum reservoirs. These correlations reveal that the critical pore-to-particle diameter ratio below which plugging occurs may be greater than the unit physical limit.
Multilateral Completions in the Granite Wash: Two Case Studies
Authors: Goodlow K. , Huizenga R. , McCasland M. , Clift D. , Neisen C. 
Published: April 2009

Abstract
This paper will detail the design and installation of two multilateral completions in the Granite Wash in the Texas Panhandle. The paper will discuss the operational aspects of the drilling programs, construction of the lateral junctions, fracture treatments of both laterals, and final realized production. Details on the completion equipment and techniques developed to meet the operational goals will also be covered.
Multilateral completions have strong economic potential in unconventional gas developments. Operators can save capital investment by accessing production from two laterals while drilling a single vertical wellbore. Greater drainage access across a section is also possible by using this technology.
The technical challenge of this project is to provide a 10,000-psi seal across the junction to selectively fracture both laterals, which requires a TAML level 4 junction. The commercial challenge is to provide this technology and install it so that economic benefits exceed those of drilling two separate wellbores. Details of how well both of these challenges were met will be discussed.
The subject wells of this paper were drilled and completed between February and September of 2008. The paper will document lessons learned, modifications needed, and relative operational success. These objectives will be presented from both the operator's and contractor's viewpoints.
Backside Auto-Injection System
Authors: Garner Ted D. 
Published: April 2009

Abstract
The Backside Auto - Injection System (BAIS) is designed to allow gas to be injected into the packerless production tubing/casing annulus intermittently without having to pull the tubing and install gas-lift mandrels and valves. This is accomplished by using a single portable wellhead compressor to collect gas from the tubing and simultaneously compress the gas down the casing-tubing annulus. The control of gas flow is directed by pressure activated motor valves. As the gas enters the bottom of the tubing, the gas-liquid ratio (GLR) is increased sufficiently to unload the wellbore liquids to the surface. Once unloaded, the gas flow is directed to sales until further loading is detected by the BAIS. This system is designed to provide liquid unloading and economic production enhancement to marginal gas wells.
Oriented Perforation in Dual Completion Wells: A Real Case in East Texas
Authors: Gama Cesar , Gerez David , Babasick Paul A. , Piedras Jose 
Published: April 2009

Abstract
Fracturing is an important technique for stimulating production in low-permeability formations, and requires special consideration in designing the preceding perforating job. Aligning the perforations along the direction of maximum geological stress, known as the preferred fracture plane (PFP), provides significant opportunities to improve the efficiency of the fracture job, maximizing ultimate production from the well.
Wells are frequently completed with multiple tubing strings (up to four in some cases), sensor lines, control lines, or other hardware that can be damaged during perforation. The traditional approach of hiring a workover rig to remove the completion prior to perforating is, in many cases, not cost effective, leading to foregone opportunities to extend production by perforating new intervals or reperforating existing producing zones. With casingless completions, even this option is not available.
A downhole orienting and imaging platform has the unique capability to orient guns along the PFP for optimal fracturing efficiency while simultaneously avoiding damage to complex downhole completions, without the expense of workover. This technology enables the enhanced production from wells that may otherwise have been uneconomical. The technique was applied during a pre-fracturing perforating job for Total E&P USA, Inc. (Total) in their Bethany field located in east Texas. The job addressed the dual objectives of orienting the perforations along the PFP, while simultaneously avoiding the parallel completion, which if perforated would open a communication path between reservoirs with different pressures.
Transient-Pressure Analysis of a Well With an Inclined Hydraulic Fracture Using Tiab's Direct Synthesis Technique
Authors: Dinh Anh V. , Tiab Djebbar 
Published: April 2009

Abstract
The purpose of this study is to develop a technique, based on the pressure derivative concept, for interpreting pressure transient tests in wells with an inclined hydraulic fracture. Detailed analysis of unsteady-state pressure behavior of fully penetrating inclined fracture in an infinite slab reservoir was provided. Both uniform flux and infinite conductivity models were considered. The study has shown that inclined fracture pressure data exhibit similar flow regimes as for vertical fracture counterpart. Those flow regimes are linear and pseudo-radial flow for both uniform flux and infinite conductivity models. However, for infinite conductivity model, a bi-radial flow regime is also observed. In the case of high formation thickness to fracture half length ratio and high angle of inclination, both uniform flux and infinite conductivity inclined fracture model exhibit an additional flow regime called early radial flow. Both bi-radial flow and early radial flow regimes for inclined hydraulic fracture have not been mentioned in the literature before.
A step by step procedure based on Tiab's Direct Synthesis (TDS) was developed in this study. Fracture properties such as half fracture length, inclination angle, formation permeability and pseudo-skin factor can be obtained from the direct interpretation of the log-log plot of pressure and pressure derivative without the need of any type curve matching. Several unique features of the pressure and pressure derivative plots of both uniform flux and infinite conductivity inclined fracture models were identified including the points of intersection of straight lines for different flow regimes. These points can be used to verify the results or to calculate unknown parameters. Equations associated with these features were derived and their usefulness was demonstrated. Numerical examples with both pressure build-up and drawdown data were also demonstrated for this procedure.