bluuebunny/crossref_metadata_2025 huggingface dataset:
Frac-and-Pack Completions of Low-Permeability Formation in West Africa
Authors: Bruggeman J. L. , de Vinck B. , van Domelen M. L. , Boissier J. C.
Published: July 2008

This paper describes the successful application of the frac-and-pack completion technique to a low-permeability oil-bearing formation in coastal Zaire, West Africa. Using various completion methods since initial field development in the early 1970s, operators have recovered less than 1 % of the estimated oil in place from this formation to-date. Encouraging results from a two-well pilot project initiated in late 1994, led to a decision to work over an additional four wells for frac-and-pack completions in 1995 as part of the pilot project.

This work centers around the Turonian formation, which is a soft, low-permeability siltstone formation. The friable nature of this formation combined with a low median sand-grain size (20 to 40 microns) has led to formation sand and fines production in some wells. Past attempts to stimulate the Turonian through matrix acidizing have been unsuccessful, and completions of the reservoir with both open- and cased-hole gravel packs have shown uneconomical production rates.

The first two frac-and-pack treatments of the pilot project, one in cased hole and one in a 15-in. underreamed open hole, were pumped through a short weight-down gravel pack assembly that allows for monitoring a live annulus during the job and accurate measurement of net fracturing pressures. The four additional frac-and-pack completions were performed with a similar downhole assembly.

This paper highlights the main aspects of this project, including the reservoir description, completion equipment, fluid and proppant selection, design and analyses of the fracture treatments, and optimization of the treatments as the project progressed. A summary of well performance following the frac- and-pack completions is also presented.
Formation Damage Due to Fines Stabilized Water-in-Oil Emulsions: A Possible Mechanism of Plugging in the Near Well Bore Area?
Authors: Kotlar H. Kr. , Selle O. M. , Kristensen M. H.
Published: July 2008

The generation of stable emulsions at reservoir temperature was investigated as a possible mechanism of formation damage in the near well-bore area. Typically, emulsions have been considered a top-side process problem. Furthermore, experimentation is often based on a set of single events and a traditional conclusion would be that emulsions are of little concern in plugging mechanisms. However, in nature single event mechanisms are scarce. Under actual reservoir conditions both generation of scale and mobilization of fines together with formation of emulsions might be simultaneous events. Thus, a combination of such mechanisms may lead to the plugging. In the present investigation a set of 11 different well parameters were tested in a factorial screening design for potentials in emulsion formation. The results from this screening design show that combinatorial effects are key events in fines stabilized emulsions. Two different North Sea degassed crudes gave emulsions under various combination of variable settings at reservoir temperature.

The present paper gives a survey on the influence of these variables on the stability and viscosity of the generated emulsions. Generation of emulsions and increase of flow viscosity might have great influence on well productivity.
Application of Fractal Analysis in Characterising and Predicting Critical Conditions for Fines Migration in Petroleum Reservoirs
Authors: Chen H. , Nguyen H. , Rahman’ S. S.
Published: July 2008

Formation damage due to fines migration is a major factor which reduces reservoir productivity. It is, therefore, essential to know the critical condition at which particles migrate in pores and subsequently plug the channels. This paper describes the application of fractal analysis for predicting critical conditions for particles to deposit in pores. The experimental data were obtained by injecting suspensions (bentonite) through a fabricated glass micro capillary (100 μm ID) at a controlled flow rate and at the same time continuously monitoring the pressure build-up across the capillary. Based on the experimental data and theoretical analysis, a criterion for predicting the critical condition for fines migration in pores is proposed.
The Use of Scale Dissolver and Scale Inhibitor Squeeze Treatments to Repair and Prevent Formation Damage in Two Statfjord Field Wells
Authors: Lejon K. , Vikane O.
Published: July 2008

Scale dissolvers have successfully been used to restore well productivity in two Statfjord Field wells suffering from scale induced formation damage. Combined with scale inhibitor treatment further production loss has been avoided. The dissolver efficiency towards BaSO4, and SrSO4, is strongly depending on high pH (pH> 9–10) in the treatment slug. Two different scale dissolvers have been tested, and are found to have equally good performance regarding dissolution capasities and effect on production. Well case histories and details about job design and production data before and after the treatments are documented. Combined scale dissolver and scale inhibitor squeeze treatment is implemented as the current scale treatment strategy for the Statfjord Field.

Introduction

The Upper and Lower Brent reservoirs in the Statfjord Field are developed with a row of sea water injectors, completed below the oil/water contact, to displace oil up structure to the east toward a row of oil producers near the crest of the structure. Key information about the Statfjord Field is listed in table 1.
Formation Damage Assessment Around Horizontal Wells During Injection Processes
Authors: Malekzadeh D. , Rahman M. M. , Day J. J.
Published: July 2008

Formation damage around horizontal wells can result in poor performance and failure of these wells. The objective of this paper is to present a new solution for transient pressure behavior of horizontal well injectors and/or producers in injection processes. Equations for productivity and injectivity of horizontal wells during injection processes are introduced that are based on the effective horizontal well length contributing to unimpaired injection or production. Effective horizontal well length in steady state reservoirs is the well length with zero skin factor that will yield the same steady state productivity or injectivity index as the one obtained with actual drilled horizontal section length with skin factor. A relationship between mechanical skin factor and effective horizontal well length is derived and explained. Guidelines for analyzing transient testing of horizontal well injectors for determination of reservoir permeability, skin factor, and effective length are presented. It was found that flow efficiency is the ratio of steady state shape factor evaluated at actual length of the horizontal section and the one evaluated at effective length. Furthermore, flow efficiency is always greater than the fraction of horizontal well contributing to unimpaired production or injection, Xf2/Xf1. This indicates that a decrease in effective length is not equal to the loss in injectivity or productivity of the horizontal well, thus implying tolerance for formation damage around these wells to a certain degree.
Performance of Fractured Horizontal Wells in High-Permeability Reservoirs
Authors: Valkó P. , Economides M. J.
Published: July 2008

Two of the most important recent developments in petroleum production are horizontal wells and high-permeability fracturing. This work combines them with potentially considerable incremental production economics. Hydraulic fractures have a distinctly defined azimuth, in almost all cases of interest; they are vertical and normal to the minimum horizontal stress direction. Horizontal wells can thus be drilled either normal or longitudinal to the fracture azimuth. The first configuration has been already considered in the literature and in practice, and is applicable for relatively low-permeability formations. The emergence of high-permeability fracturing, also apparently successful in a number of fields, often results in low dimensionless conductivity hydraulic fractures. The possibility of fracturing horizontal wells longitudinally may have the net effect of installing a high-conductivity streak in an otherwise limited conductivity flow conduit. A rigorous model was constructed to describe this configuration. This paper presents comparative production rates and cumulative productions for longitudinally fractured horizontal wells vis a vis vertical fractured wells and unfractured horizontal wells. The range of attractiveness of the individual options is presented in the framework of discounted revenues.
A Phenomenological Modeling of Critical Condensate Saturation
Authors: Fang Fang , Firoozabadi Abbas , Abbaszadeh Maghsood , Radke Clay
Published: July 2008

We have developed a phenomenological model for critical condensate saturation. This model reveals that critical condensate saturation is a function of surface tension and contact angle hysteresis. On the other hand, residual oil saturation does not have such a dependency. Consequently, the selection of fluids in laboratory measurements for gas condensate systems should be made with care.
Successful Integrated Engineering Service Contract in South China Sea
Authors: Sanders T. K. , Huculak Brian , Dale Dana , Jiang Zhang Ming
Published: July 2008

An Integrated Engineering Service (IES) Contract covering drilling and completion services was formed to develop two sixteen well platforms for Phillips Petroleum International Corporation Asia (PPICA) in the South China Sea. The purpose of the contract was to improve well quality and to reduce the cost and development time to PPICA by taking advantage of existing service company/lead contractor infrastructure in the area. Through a cooperative team environment, a cycle of continuous improvement has resulted in dramatically reduced drilling/ completion times, improved production, and a much lower development cost to the operator.

This paper views the IES relationship from both the per-spective of the operator and the lead contractor and its sub-contractors. It reviews in detail: 1.) the project history and background (including why an IES Contract was the right fit in this case) 2.) the "Team Xijiang" structure, roles and responsibilities, and decision making process 3.) the pricing mecha-nisms and how interests are aligned through incentive pricing 4.) the continuous improvement cycle and 5.) the actual results of the project as compared to anticipated results from previous experience in the area. This new business relationship has laid important groundwork for future opportunities in the industry, for both the operator and lead contractor. An atmosphere of cooperation and trust has removed many of the. barriers that exist in a traditional buyer/supplier relationship (or even in an expanded alliance).

By empowering team members to make decisions at the lowest possible level, personnel from all organizations involved are encouraged to contribute freely to the overall success of the project. The industry is continually faced with the need to improve efficiencies through unique solutions to problems. For any given circumstance, there are numerous alternatives to meet the need. In this case, employing an Integrated approach via one lead contractor, has been a great success.
Application of a Multi-Purpose Compositional Simulator in Designing Steam Injection Projects
Authors: Cicek O. , Ertekin T.
Published: July 2008

In the design of an optimum enhanced oil recovery operation an accurate areal and vertical mapping and analysis of the simulation results plays a fundamental role. In this type of analysis not only should the finer details of the reservoir be considered, but also the grid system superimposed over the domain of interest should exhibit compatibility and consistency with the actual physics of the problem. This will help in accurate characterization of the reservoir and the ongoing physical processes within the domain of interest.

The implications of the aforementioned statements are investigated with the aid of developing a 3-D fieldscale steam injection simulator. The multi-phase mass and energy transport equations are based on compositional balances. In the model the gravitational and capillary forces are accounted together with the viscous flow phenomenon. A fully implicit treatment is used at the multi-block production and injection wells to couple the wellbore to the reservoir. A fully implicit technique is utilized in the solution of the nonlinear system of equations. The model is capable to solve (nh+5) primary variables simultaneously where "n. c" represents the number of hydrocarbon components that can be considered.

A systematic analysis of the areal and vertical distribution of parameters such as pressure, temperature, phase saturations and composition is conducted. Through this detailed analysis the ever-changing relative effects of the various dominant forces on the establishment of production mechanisms and ultimately on the oil recovery are studied.

The fully implicit formulation, which assumes all the reservoir parameters and operational parameters to be functions of all primary variables identified, makes it possible to focus on any parameter and investigate its effects on oil production. Both qualitative and quantitative implications of capillary pressure on the oil production are observed to be strong functions of the size and uniform nature of the grid constructed over the computational domain.

The proposed model provides some significant insight into the displacement mechanisms and aids us in developing a comprehensive understanding of the nature and magnitude of die forces and controlling parameters. Such an understanding will help in the design of specifics of a recovery operation.
Well Testing and Evaluation of Tubing-Conveyed Extreme Overbalanced Perforating
Authors: Azari Mehdi , Burleson John , Soliman Mohamed , Mason Justin , Gazi Naz
Published: July 2008

Traditionally, underbalance perforating has been the preferred perforation technique. Recently, however, a new extreme overbalance perforating (EOBP) that has the potential to improve the completion efficiency of a well without additional stimulation has been introduced. With this method a well with a fluid column is pressurized with nitrogen to above fracturing pressure of the formation before the gun is fired. Gas is then injected, with or without acid or proppants, to create short fractures that extend from the perforation tunnels. The presence of gas lowers the amount of liquid that contacts with the formation, facilitates the well's coming into production after perforation, and results in less formation damage.

This new EOBP method creates highly conductive short fractures, the benefits of which outweigh any restriction that may be caused by perforating debris. The debris that exits the gun when it detonates will be pushed away from the wellbore during the pumping stage, and this will greatly diminish any adverse effects on productivity that overbalanced perforating could cause. This can be considered as a near-wellbore stimulation method that also improves the completion efficiency of a well by allowing perforating and stimulation to be accomplished in one operation. By performing two or more completion procedures during a single trip into the wellbore, service operators have been able to generate economical advantages.

There are numerous ways in which EOBP may be performed. This paper will cover the design, planning techniques, and equipment that can be used to perform tubing-conveyed overbalance perforating. Examples and field cases will show scenarios in which wells with a variety of wellbore conditions such as open perforations and packerless and tubingless installations can be perforated in an extremely overbalanced condition.

An analysis technique that can be applied to a short falloff test immediately following the perforation treatment as well as the standard well testing is also described in this paper. The method of analysis can be used to calculate skin damage, formation permeability, reservoir pressure, and if applicable, fracture parameters such as fracture half-length and conductivity. Several field cases are included to illustrate application of this method.
Design and Evaluation of a Simple Signaling Device for Live Traps
Authors: BENEVIDES FRANCIS L. , HANSEN HEIDI , HESS STEVEN C.
Published: July 2008

Abstract: Frequent checks of live traps require enormous amounts of labor and add human scents associated with repeated monitoring, which may reduce capture efficiency. To reduce efforts and increase efficiency, we developed a trap‐signaling device with long‐distance reception, durability in adverse weather, and ease of transport, deployment, and use. Modifications from previous designs include a normally open magnetic switch and a mounting configuration to maximize reception. The system weighed <225 g, was effective ≤17.1 km, and failed in <1% of trap‐nights. Employing this system, researchers and wildlife managers may reduce the amount of effort checking traps while improving the welfare of trapped animals.
Mallard Harvest Distributions in the Mississippi and Central Flyways
Authors: GREEN ADAM W. , KREMENTZ DAVID G.
Published: July 2008

Abstract:The mallard (Anas platyrhynchos) is the most harvested duck in North America. A topic of debate among hunters, especially those in Arkansas, USA, is whether wintering distributions of mallards have changed in recent years. We examined distributions of mallards in the Mississippi (MF) and Central Flyways during hunting seasons 1980–2003 to determine if and why harvest distributions changed. We used Geographic Information Systems to analyze spatial distributions of band recoveries and harvest estimated using data from the United States Fish and Wildlife Service Parts Collection Survey. Mean latitudes of band recoveries and harvest estimates showed no significant trends across the study period. Despite slight increases in band recoveries and harvest on the peripheries of kernel density estimates, most harvest occurred in eastern Arkansas and northwestern Mississippi, USA, in all years. We found no evidence for changes in the harvest distributions of mallards. We believe that the late 1990s were years of exceptionally high harvest in the lower MF and that slight shifts northward since 2000 reflect a return to harvest distributions similar to those of the early 1980s. Our results provide biologists with possible explanations to hunter concerns of fewer mallards available for harvest.
Estimating Numbers of Black Brant Using Sequential Spring‐Staging Sites
Authors: HAGMEIER KATHERINE R. , SMITH BARRY D. , BOYD W. SEAN
Published: July 2008

Abstract: Estimating total number of birds using a particular staging site during migration is challenging because counts alone do not account for turnover in the local population. Robust statistical methods are needed to more fully assess the conservation value of such sites. We used the multi‐strata model in Program MARK to estimate time‐dependent transition probabilities between sequential staging sites to estimate lengths of stay for spring‐staging Pacific black brant (Branta bernicla nigricans) on the Fraser River delta and Parksville‐Qualicum areas in the Strait of Georgia, British Columbia, Canada. Using resightings of marked individuals in combination with ground counts, we estimated the total number of brant, with associated uncertainties, staging at these sites during the spring migrations of 1999 and 2000. We estimated between 28,927 and 33,181 individual brant transited the Fraser River delta and Parksville‐Qualicum sites in 1999 and between 21,621 and 25,405 individuals in 2000. These totals correspond to approximately 18–26% of the entire Pacific Flyway brant population, suggesting the need for continued conservation and management efforts at these sites. Given the importance of staging sites to migratory populations, we believe this method could be applied to other species and locations.
Conserving Waste Rice for Wintering Waterfowl in the Mississippi Alluvial Valley
Authors: KROSS JENNIFER P. , KAMINSKI RICHARD M. , REINECKE KENNETH J. , PEARSE AARON T.
Published: July 2008

Abstract: Rice lost before or during harvest operations (hereafter waste rice) provides important food for waterfowl in the Mississippi Alluvial Valley, USA, but >70% of waste rice is lost during autumn. We conducted experiments in 19 production rice fields in Arkansas and Mississippi during autumns 2003 and 2004 to evaluate the ability of common postharvest practices (i.e., burn, mow, roll, disk, or standing stubble) to conserve waste rice. We detected a postharvest treatment effect and a positive effect of initial abundance of waste rice on late‐autumn abundance of waste rice (P ≤ 0.022). Standing stubble contained the greatest abundance of waste rice followed by burned, mowed, rolled, and disked stubble. We recommend standing stubble or burning to maximize waste rice abundance for wintering waterfowl.
Demography of Ferruginous Hawks Breeding in Western Canada
Authors: SCHMUTZ JOSEF K. , FLOCKHART D. T. TYLER , HOUSTON C. STUART , MCLOUGHLIN PHILIP D.
Published: July 2008

Abstract: We assessed age‐dependent survival, site‐fidelity, and, together with data on prey and reproduction, trends in the population of ferruginous hawks (Buteo regalis) breeding in western Canada. Our analysis included 7,129 ferruginous hawks banded near Hanna, Alberta, and Kindersley‐Alsask, Saskatchewan, from 1972 to 2003. We estimated annual adult survival rate to be 0.708 (SE = 0.024) and first year survival for nestlings was 0.545 (SE = 0.147). Resighting probability was modeled as a constant for nestlings (0.009, SE = 0.010), but it varied among years for adults consistent with our sampling efforts. Band reporting rate was at 0.022 (SE = 0.007) for both nestlings and adults. Fidelity to the study site was 1.00 (SE = 0.000) for adults and 0.035 (SE = 0.014) for nestlings. Nesting density ranged from 3.1 to 14.0 pairs/100 km2 and averaged 9.8 pairs/100 km2. We observed an average clutch size of 3.2 (SE=0.06) and brood sizes of 2.71 (SE=0.07) near Hanna and 2.79 (SE = 0.99) at Kindersley‐Alsask. Richardson's ground squirrels (Spermophilus richardsonii) made up 95% of ferruginous hawk prey. Prey availability was positively correlated with number of offspring near Hanna and Kindersley‐Alsask. We believe the lower than expected adult survival did not result in population decrease; rather, declines in reproduction resulting from declines in the abundance of ground squirrels better explain an observed 4.5‐fold decline in nesting densities during the study. The results suggest that ferruginous hawk management should address prey in addition to habitat management, and that management needs are regional in scope with particular emphasis on the breeding range within the northern Great Plains.
Effects of Understory Vegetation Management on Brood Habitat for Northern Bobwhites
Authors: BURKE JASON D. , CHAMBERLAIN MICHAEL J. , GEAGHAN JAMES P.
Published: July 2008

Abstract: Northern bobwhite (Colinus virginianus) populations have experienced severe declines for several decades, and declines have been particularly precipitous in the southern United States. These declines are partially attributable to large‐scale conversions of potential habitat to short‐rotation pine (Pinus spp.) forests managed for wood fiber production and fire exclusion in pine‐dominated landscapes. We used standard arthropod sampling techniques, human‐imprinted bobwhite chicks, and vegetation response to evaluate effects of different understory vegetation management practices on brood habitat quality within a commercially managed pine forest in Louisiana, USA, during 2002–2005. Specifically, we evaluated effects of mowing, prescribed fire during the growing season, prescribed fire in combination with imazapyr application, and no vegetation management on arthropod abundance and diversity, vegetation response, and the probability of bobwhite chicks successfully capturing an arthropod. Bobwhite chicks were more successful at capturing arthropods, and arthropod abundance and diversity were greatest, in plant communities managed using prescribed fire and imazapyr. Forest stands managed using a combination of fire and imazapyr were managed primarily to benefit the federally endangered red‐cockaded woodpecker (Picoides borealis; RCW). Our findings suggest that management directed toward improving forest condition for RCWs improves habitat quality for brooding bobwhites. However, bobwhite chicks in our study area were less successful at capturing arthropods than were chicks in other studies in the southeastern United States. Brood‐rearing habitat in pine forests similar to those we studied may be of generally poor quality, and could be related to precipitous declines of bobwhites in the West Gulf Coastal Plain. Managers should recognize that creating high‐quality brood habitat in forests similar to those we studied will require more intensive management of understory vegetation than we studied.
Livestock Protection Dogs for Deterring Deer From Cattle and Feed
Authors: VERCAUTEREN KURT C. , LAVELLE MICHAEL J. , PHILLIPS GREGORY E.
Published: July 2008

Abstract: Disease transmission between wildlife and livestock is a worldwide issue. Society needs better methods to prevent interspecies transmission to reduce disease risks. Producers have successfully used livestock protection dogs (LPDs) for thousands of years to reduce predation. We theorized that LPDs raised and bonded with cattle could be used to also reduce risk of bovine tuberculosis (Myobacterium bovis; TB) transmission between white‐tailed deer (Odocoileus virginianus) and cattle by minimizing contact between the 2 species and use of cattle feed by deer. We evaluated 4 LPDs over 5 months, utilizing 2 data collection methods (direct observation and motion‐activated video) on deer farms that supported higher densities than wild populations. Dogs were highly effective in preventing deer from using concentrated cattle feed (hay bales), likely the greatest risk factor of TB transmission on farms. Dogs also prevented deer from approaching cattle in core areas of pastures (near hay bales) and were very effective throughout pastures. Our research supports the theory that LPDs, specifically trained to remain with cattle, may be a practical tool to minimize potential for livestock to contract TB from infected deer in small‐scale cattle operations. Where disease is present in deer, it may be possible to reduce the potential for disease transmission by employing LPDs.
Productivity Estimates From Upland Bird Harvests: Estimating Variance and Necessary Sample Sizes
Authors: HAGEN CHRISTIAN A. , LOUGHIN THOMAS M.
Published: July 2008

Abstract: Harvest of upland game birds in concert with sampling of age ratios from wings can yield important biological information about populations. Although estimates of productivity are commonly produced, they are often not accompanied by a measure of variance. Thus, we developed standard error estimates for sample productivity ratios, compared 4 methods for creating confidence intervals for population productivity ratios, and developed a test and the corresponding sample size requirements for comparing 2 population productivity ratios. We applied these techniques to greater sage‐grouse (Centrocercus urophasianus) wing‐data collected in Oregon, USA (1993–2005). Computer simulations indicated that backtransforming the Wilson's score interval on the proportion of immatures in the sample results in the most reliable confidence intervals among the methods considered. We recommend to managers measuring conservation action outcomes with productivity ratios to consider the appropriate sample sizes for the spatial and temporal scale of their monitoring programs.
Hair‐Trap Efficacy for Detecting Mammalian Carnivores in the Tropics
Authors: CASTRO‐ARELLANO IVAN , MADRID‐LUNA CARMINA , LACHER THOMAS E. , LEÓN‐PANIAGUA LIVIA
Published: July 2008

Abstract: Direct studies of mammalian carnivores are challenging due to the animals' secretive nature and the high costs associated with their capture and handling. Use of noninvasive hair sampling to survey these reclusive species has great potential as an alternative, with wide applicability in ecology and conservation. Hair‐trapping has been extensively used for focal studies of temperate mammals, but its use and applicability as a means to survey mammals in tropical environs has never been addressed. We evaluated the effectiveness of 2 hair‐trap types and 2 scents along an elevational gradient within El Cielo Biosphere Reserve (ECBR, Mexico) to detect presence of carnivores. Hair‐traps that used roofing nails as a hair‐collecting surface collected more hairs and detected a greater number of species than did hair‐traps that used velcro strips. Different scent treatments (commercial fragrance and catnip oil) did not differ for these same variables. Of successful nail hair‐traps, 60% collected ≥20 hairs (max. = 439), providing enough material for DNA analyses. Hair‐trap surveys detected 74% of the potential target mammal species at ECBR with only 19 days of field effort. Developing countries have limited budgets for biodiversity monitoring and hair‐traps compare favorably with other methods with a high cost‐benefit ratio. Hair‐traps are inexpensive, portable, can be made with over‐the‐counter materials, and can be successfully used to collect data applicable to population and genetic studies of tropical carnivores.
Behavior of Walk‐Hunters and Pointing Dogs During Northern Bobwhite Hunts
Authors: MECOZZI GRANT E. , GUTHERY FRED S.
Published: July 2008

Abstract: Data on the behavior of walk‐hunters and pointing dogs aids in understanding and managing quail harvest. We collected Global Positioning System track logs and recorded behaviors of hunters and dogs on northern bobwhite (Colinus virginianus) hunts in Oklahoma (n = 43), Texas (n = 43), and Missouri (n = 7), USA, during the 2005–2006 and 2006–2007 hunting seasons. Hunter velocity averaged 0.8 ± 0.03 (SE) m/second both seasons (n = 85) and pooled (95% CL overlap) velocity of bird dogs was 2.5 ± 0.07 (SE) m/second (n = 154). Hunters spent 60.5 ± 2.4% (SE) of their time walking in 2005–2006 (n = 45) versus 75.2 ± 3.5% (SE) in 2006–2007 (n = 48); respective figures for ranging by dogs were 50.2 ± 2.2% (n = 57) versus 82.0 ± 1.3% (SE; n = 97). Mean duration of a hunt declined from 82.3 ± 8.16 (SE) minutes (n = 45) to 50.2 ± 5.1 (SE) minutes (n = 48) between seasons. Variation in bobwhite abundance was the primary cause of seasonal variation in hunter and dog behaviors because covey‐associated activities declined as quail abundance declined. With our results and those of previous workers, managers have first‐generation estimates of all variables in hunter‐covey interface models for managing bobwhite harvest on discrete areas.
Signaling Costs: Why Don't More Firms Petition for Protection?
Authors: Malhotra Nisha
Published: July 2008

The main aim is to question why we don't see more firms petitioning for import relief. It is well accepted that petitioning itself can restrain imports, lead to higher prices and hence higher profits (in the short run). What prevents more firms from filing for protection? It may be that petitioning reflects cost inefficiency on the part of the petitioning firm, and concerns about revealing this information might act as a deterrent for firms to come forward with their complaints. However, in a declining industry where a large number of firms are contemplating exit, petitioning could be a signal that the firm expects to remain in the market for the near future. The signaling hypothesis is tested by comparing the stock market response of an antidumping petition for petitioning firms and non-petitioning firms producing the same product.
Trade Associations as Industry Reputation Agents: A Model of Reputational Trust
Authors: Tucker Andrew
Published: July 2008

Scholars have started to focus on the ways in which firms manage their reputations through collective action. Collective reputation management is most often carried out through trade associations (TAs). But what do these TAs actually do? How do they further their members' interests with stakeholders like regulators, industry financial analysts, employees, suppliers, and the media? Informed by a rich set of 43 qualitative interviews with the trade associations (TAs) representing the UK's 24 largest business sectors, the paper builds a model of the reputational incentives that drives the dynamic relationship between trade associations, firms and multiple stakeholder groups. The paper's preliminary empirical research coupled with the conceptual model provides five directions for future research.
Antidumping Duties in the Agriculture Sector: Trade Restricting or Trade Deflecting?
Authors: Malhotra Nisha , Rus Horatiu , Kassam Shinan
Published: July 2008

In this article we analyze whether US antidumping (AD) duties in the agricultural sector are effective in restricting trade. More specifically, does imposing an antidumping duty restrict imports of the named commodity or are imports deflected from countries named in the AD petition to countries not named in the petition? We find that AD duties have significantly restricted imports of agricultural commodities from countries named in the petition. However, our results also indicate that, unlike the manufacturing sector in the US, there was little trade diversion towards countries not named in the petition. Our results indicate that AD is a plausible protectionist policy in the agriculture sector.
The Undervaluation of the Yuan Dispute: Is a Repetition of Germany's Experience in 1969 Necessary, Inevitable or Desirable? A Comment and Reply to John A. Tatom
Authors: Oberpriller Christian M. , Sauer Beate , Sell Friedrich L.
Published: July 2008

The present article is a reply to the article by John A. Tatom titled "The US-China Currency Dispute: Is a Rise in the Yuan Necessary, Inevitable or Desirable?," recently published in this journal. We found that John Tatom seems to only give a partial description of the US-Chinese economic relations, of the main features of the Chinese economy, and also of the macroeconomic policy options available to China. We argue that the real exchange rate is not the appropriate measure for a currency undervaluation, but it is the continuous, one-directional and accelerating accumulation of foreign exchange reserves. We also argue that the likely improvement in the US trade balance deficit caused by an appreciating Yuan will not be offset by growing US trade balance deficits with other East Asian countries. Furthermore, giving up the actual currency peg will benefit rather than harm China, provided that the steps towards Yuan flexibility will be taken in the right sequence and order. We hold that a revaluation of the Yuan is necessary, inevitable and desirable just as much as it happened to be with the Deutschmark in 1969. It would not "damage Chinese development." China needs a Yuan appreciation mainly in its own interest to assure domestic financial market stability, and to avoid an overheating of its economy and a soaring inflation.
Competition between Latin America and China for US Direct Investment
Authors: De la Cruz Gallegos Jose Luis , Ivanova Boncheva Antonina , Ruiz-Porras Antonio
Published: July 2008

There is a belief that the Chinese economy competes with the Latin-American ones for investment flows. Here we analyze the determinants of the US FDI outflows to the most representative Latin-American economies. We develop such assessments with a double-procedure cointegration analysis based on the time-series methodologies of Toda and Yamamoto (1995) and Liu, Song and Romilly (1997). The results suggest that long-run investment to the Latin-American region mainly depends on the performance of the US economy. Furthermore, they suggest the existence of a substitution effect between the Latin American countries and China for US investment flows.
Closer Economic Integration and Corporate Tax Systems
Authors: Clausing Kimberly A.
Published: July 2008

This article investigates two aspects of corporate income taxation: the determinants of corporate tax rates and the determinants of corporate tax revenues. In the context of theoretically informed empirical models, the analysis examines the influence of increasing economic integration on corporate tax rates and corporate tax revenues, focusing in particular on the case of European Union member and applicant countries. The investigation utilizes a data set of 36 OECD and European countries over the period from 1979 to 2002. Findings are consistent with theoretical expectations: more integrated countries chose lower corporate tax rates, while larger countries, those with bigger governments, and those with higher individual income tax rates chose higher rates. Corporate tax revenues are found to be parabolically related to tax rates. Further, this parabolic relationship is steeper as economies are more integrated, implying a lower revenue-maximizing tax rate for such countries.
The Problems Facing the Doha Development Agenda
Authors: Christy David S.
Published: July 2008

The prospects of successfully concluding the Doha Development Agenda negotiations in 2008 are poor. Even a basic agreement on major issues with details to be filled in later is unlikely. Possibly, there may be an agreement this year on modalities.

Deep divisions remain in all major negotiating areas—agriculture, non-agricultural market access (NAMA), services and rules. Moreover, in some respects, the Members do not even agree on the form the negotiations should take, e.g., the level of importance to be accorded to services.
The Limbaugh Effect: A Rush to Judging Cross-Party Raiding in the 2008 Democratic Nomination Contests
Authors: Donovan Todd
Published: July 2008

This paper examines the potential for strategic Republican crossover voting in the March 4, 2008 Democratic primaries. Some observers note that conservative media figures encouraged Republicans to raid the Democratic primary in order to weaken the Democratic Party's chances in the November election. Analysis of exit poll data from 38 states suggests that Republicans may have been voting strategically in Democratic primaries, but there is little evidence that March 4th was unusual in the scope of strategic behavior.
Review of The Second Civil War: How Extreme Partisanship Has Paralyzed Washington and Polarized America and Pennsylvania Avenue: Profiles in Backroom Power
Authors: Brewer Mark
Published: July 2008

Ronald Brownstein's The Second Civil War and John Harwood and Gerald F. Seib's Pennsylvania Avenue each attempt to explain what the authors see as the gridlock and polarization that characterize contemporary American politics. Brownstein's historical approach provides much needed perspective, while Harwood and Seib's elite interviews offer an inside glimpse on how deals get done (or not) in Washington.
The Role of Farmers' Risk aversion for Contract Choice in the US Hog Industry
Authors: Zheng Xiaoyong , Vukina Tomislav , Shin Changmock
Published: July 2008

In this paper we estimate the farmers' side welfare effects of a hypothetical regulatory scenario that would partially eliminate production contracts in the hog industry. Using the Agricultural Resource Management Survey (ARMS) data for 2004, farmers' production costs under different marketing arrangements are estimated and then used to recover their individual risk aversion parameters with the help of a structural expected profit maximization model. The results show that farmers who use production contracts are more risk averse than farmers who use spot markets or marketing contracts. The regulation that forces producers to market their hogs in a riskier marketing channel relative to the channel they themselves selected imposes large welfare losses on the affected farmers.
Using the Kalman Filtering for the Fault Detection and Isolation (FDI) in the Nonlinear Dynamic Processes
Authors: Chetouani Yahya
Published: July 2008

This paper presents a Fault Detection and Isolation (FDI) method for stochastic nonlinear dynamic systems. First, the developed fault detection method is based on statistical information generated by the extended Kalman filter (EKF) and is intended to reveal any drift from the normal behaviour of the process. A fault of a chemical origin in a perfectly stirred batch chemical reactor, occurring at an unknown instant, is simulated. The purpose is to detect the presence of this abrupt change, and pinpoint the moment it occurred. It is also shown that the convergence of the EKF is accomplished more or less rapidly according to the nature of the noise generated by the measurement sensors. The state estimate is observed and discussed, as well as the time delay in detection according to the decision threshold. Then, this study shows another method of tackling the problem of the physical origin diagnosis of faults by combining the technique based on the standardized innovations and the technique using the multiple extended Kalman filters for a strongly non-stationary nonlinear dynamic system. The usefulness of this combination is the implementation of all the fault dynamics models if the decision threshold on the standardized innovation exceeds a determined threshold. In the other case, one EKF is enough to estimate all the process state. An algorithm is described and applied to a perfectly stirred chemical reactor operating in a semi-batch mode. The chemical reaction used is an exothermic second order one.
Electromigration of Co-Ions and Counter-Ions through Cation Exchange Membranes
Authors: Uresandi Maria , Parrondo Javier , Mijangos Federico
Published: July 2008

Polymeric cation exchange membranes (PEM) are used in fuel cell technology. These membranes act like a physical barrier between the anode and cathode but the diffusion through the membrane should allow the transport of protons from the anode to cathode at a rate that is enough to supply the energy requirements. They avoid the direct reaction of oxygen and hydrogen that would diminish fuel cell efficiency.The membrane has to be conditioned before use. This conditioning step changes the membrane counter-ion and modifies its water content which affects the diffusion coefficients. Diffusion experiments were carried out in a reactor with two semi-cells of 250 mL with the membrane placed between the semi-cells. Diffusion through the membrane was studied using two system configurations: without applying any potential and applying zero potential drop across the membrane using two Ag/AgCl electrodes.Diffusion of chloride through the membrane is related to membrane permselectivity. Diffusion of hydrogen chloride was followed by measuring the pH of the diluted dissolution and the potential drop across the membrane with two Ag/AgCl reference electrodes. Several experiments were carried out using initial concentrations between 10-3 M to 0.1 M. Results were modelled using NernstPlanck equations. Results obtained show that the diffusion of a co-ion is a very slow process and that the conditioning step enhances proton transport. Diffusion coefficients obtained were in the range of 10-11 cm2/s for chloride and 10-7 for proton.
Analysis of the Behaviour of Different Mixed Oxides in the Treatment of Cl-VOC Containing Gas Streams
Authors: de Rivas Beatriz , López-Fonseca Rubén , Gutierrez-Ortiz Miguel A , Gutiérrez-Ortiz Jose I
Published: July 2008

The present work deals with the catalytic behaviour of a series of ceria and manganese-based catalysts for the deep single combustion chlorinated compounds in air. Our attention is focused on both activity and product selectivity of Ce/Zr and Mn/Zr in the oxidation of 1,2-dichloroethane (1,000 ppm) and trichloroethylene (1,000 ppm). This study also makes an attempt to establish a correlation between physico-chemical properties and catalytic performance.Both series of mixed oxides exhibited a noticeable activity in the combustion of both compounds, Ce0.5Zr0.85O2, Ce0.5Zr0.5O2 and Mn0.4Zr0.6O2 being the samples with the most promising catalysts. A remarkable acidity and readily accessible active oxygen species played a key role in determining the catalytic behaviour. As for the product selectivity, CO2, CO, HCl and Cl2 were the main products. The yield of CO2 and Cl2 was favoured as cerium or manganese content was increased. However, selectivity to chlorine was noticeably limited by the addition of stream in favour of HCl.
SFGP 2007 - Two-Step Process of Thermo-Chemical Conversion of Wood Waste Contaminated by Aminoplast Resins
Authors: Girods Pierre , Rogaume Yann , Dufour Anthony , Rogaume Caroline , Zoulalian André
Published: July 2008

The aim of this study is to develop a two-steps process of thermal valorisation of wood waste containing urea-formaldehyde and melamine-formaldehyde resins such as wood board or laminated flooring. The first step of the process known as "refinement" is a low temperature pyrolysis between 250°C and 300°C which aims to remove nitrogen thermally. This step is studied by IRTF spectrometry. Ultimate analysis enables the assessment of the efficiency of the process in terms of nitrogen removal. It is shown that around 68 wt% of nitrogen can be removed during this first stage and that a 250°C treatment gives the best results in terms of energy recovery. The second step is a fast pyrolysis of the residue of the first step which aims to produce combustible gas. Three temperatures of pyrolysis are studied (800°C, 900°C and 1000°C) by GC-TCD analysis. It is shown that the temperature of the pyrolysis has an influence on the volume of gas produced and on its Low Heating Value. The best results are obtained with the 1000°C pyrolysis which produces a higher volume of gas and gives the best energetic efficiency. The residual char after fast pyrolysis step still contains energy and nitrogen. Its combustion would improve the energetic efficiency of the process but a conversion into an activated char has to be considered to improve the economic efficiency of such a type of waste disposal process.
CFD Simulation of Gas-Liquid Flows in a Reactor Stirred by Dual Rushton Turbines
Authors: Kasat Gopal R. , Pandit Aniruddha B. , Ranade V. V
Published: July 2008

In the present work, we have simulated gas-liquid flows in a tall stirred reactor equipped with dual Rushton turbines. A two fluid model along with the standard k-? turbulence model and modified drag coefficient, (proposed by Khopkar & Ranade, 2006) accounting for the effect of bulk turbulence, was used to simulate the dispersed gas-liquid flow in a stirred reactor. The multiple reference frames (MRF) approach was used to simulate impeller rotation in a fully baffled reactor. The computational model was mapped on to a commercial solver FLUENT 6.2 (of Fluent Inc. USA). The model was used to simulate three distinct flow regimes in a gas-liquid stirred reactor: L33-VC (lower impeller-upper impeller), S33-VC and VC-VC. The model predictions were compared with the published experimental data of Bombac & Zun (2000). The predicted results show good agreement with the experimental data for all the three flow regimes. The computational model presented in this work would be useful for simulating different flow regimes in a gas-liquid stirred vessel.