bluuebunny/crossref_metadata_2025 huggingface dataset:
Simple Sequence Repeat-Based Comparative Genomics Between Brassica rapa and Arabidopsis thaliana: The Genetic Origin of Clubroot Resistance
Authors: Suwabe Keita , Tsukazaki Hikaru , Iketani Hiroyuki , Hatakeyama Katsunori , Kondo Masatoshi , Fujimura Miyuki , Nunome Tsukasa , Fukuoka Hiroyuki , Hirai Masashi , Matsumoto Satoru
Published: May 2006

An SSR-based linkage map was constructed in Brassica rapa. It includes 113 SSR, 87 RFLP, and 62 RAPD markers. It consists of 10 linkage groups with a total distance of 1005.5 cM and an average distance of 3.7 cM. SSRs are distributed throughout the linkage groups at an average of 8.7 cM. Synteny between B. rapa and a model plant, Arabidopsis thaliana, was analyzed. A number of small genomic segments of A. thaliana were scattered throughout an entire B. rapa linkage map. This points out the complex genomic rearrangements during the course of evolution in Cruciferae. A 282.5-cM region in the B. rapa map was in synteny with A. thaliana. Of the three QTL (Crr1, Crr2, and Crr4) for clubroot resistance identified, synteny analysis revealed that two major QTL regions, Crr1 and Crr2, overlapped in a small region of Arabidopsis chromosome 4. This region belongs to one of the disease-resistance gene clusters (MRCs) in the A. thaliana genome. These results suggest that the resistance genes for clubroot originated from a member of the MRCs in a common ancestral genome and subsequently were distributed to the different regions they now inhabit in the process of evolution.
RADPLAT: An Alternative to Surgery?
Authors: Alkureishi Lee W.T. , de Bree Remco , Ross Gary L.
Published: May 2006

Head and neck cancer frequently presents at a late stage, leading to a poor prognosis despite optimal treatment with surgery and/or radiotherapy. Chemotherapy for advanced disease has shown little benefit as a single-modality treatment, and the use of concurrent chemoradiation is limited by problems with severe toxicity at higher doses. RADPLAT is the acronym used to describe a new technique, combining intra-arterial delivery of cisplatin with systemic neutralization by i.v. sodium thiosulphate, and concurrent radiotherapy. This allows very high cisplatin dose intensities to be used while potentially minimizing adverse systemic effects. Initial results suggest that excellent locoregional control rates are achievable in patients with unresectable disease, with a favorable side-effect profile when compared with conventional chemoradiation protocols. In addition, RADPLAT may potentially be of benefit in selected patients with resectable disease, allowing for preservation of organ function and quality of life without compromising locoregional control or survival. While current phase II data are encouraging, phase III randomized controlled trials are required in order to directly compare RADPLAT with i.v. chemoradiation therapy, the current standard of care. This article reviews the evolution of the RADPLAT concept, from initial clinical trials to its current application in the treatment of patients with advanced head and neck cancer.
Lung Cancer Screening
Authors: Ganti Apar Kishor , Mulshine James L.
Published: May 2006

Learning Objectives

After completing this course, the reader will be able to: Identify the role of screening in the diagnosis of lung cancer.Discuss the advantages and disadvantages of screening for lung cancer using CT scans.Describe the impact of advances in technology on screening for lung cancer.Name the nonimaging modalities that may play a role in lung cancer screening in the future.

Access and take the CME test online and receive 1 AMA PRA category 1 credit at CME.TheOncologist.com

Advances in imaging technology have ushered in a new era for lung cancer screening in high-risk individuals using computed tomographic (CT) scans. Although most published studies are nonrandomized observational cohorts of volunteers, the ability of CT scans to detect early stage lung cancer is undisputable. What is unresolved is the ability of spiral CT screening to affect lung cancer-related mortality. A large randomized trial sponsored by the National Cancer Institute to address this question is currently under way. Genomic and proteomic approaches promise to complement the ability of spiral CT to detect early lung cancer in the next few years. Currently, the decision to screen for lung cancer should involve a careful discussion with the individuals involved about the potential advantages, costs, and drawbacks of the approach.
Pleiotropic effects of the steroid hormone 1,25-dihydroxyvitamin D3 on the recruitment of mesenchymal lineage progenitors in fetal rat calvaria cell populations
Authors: Zhang Shulin , Chan Melinda , Aubin Jane E
Published: May 2006

The steroid hormone 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) inhibits osteogenesis while stimulating adipogenesis in vitro. We hypothesized that 1,25(OH)2D3 redirects the fate of osteoblast/adipocyte bipotential progenitors and other potential progenitors towards adipogenesis, a process possibly underlying the pathogenesis of osteopenic diseases such as osteoporosis. We therefore tested the global effects of 1,25(OH)2D3 on the recruitment of mesenchymal progenitors including osteogenic, chondrogenic, adipogenic and myogenic lineages (colony forming cell (CFC)-osteoblast (CFC-O), CFC-chondrocyte (CFC-C), CFC-adipocyte (CFC-A), and CFC-myoblast (CFC-M) respectively) in rat calvaria (RC) cell populations using gene expression profiling of single cell-derived colonies. Based on expression of lineage specific transcripts, 86% of single cell-derived colonies in untreated cultures simultaneously co-expressed transcripts of two, three, or four of the mesenchymal lineages tested. The distribution of mesenchymal progenitors in 1,25(OH)2D3-treated cultures was significantly changed compared with the control group, i.e. CFC-O were reduced (from 6 to 0%) and CFC-O/A bipotential (0 to 8.2%), CFC-C (4 to 10.2%) and CFC-Fibroblast (CFC-F) (4 to 16%) were increased. 1,25(OH)2D3 did not affect the frequency of tri- or tetra-lineage colonies. Single lineage CFC-A colonies were not detected in either the control or 1,25(OH)2D3 treatment group under the conditions tested.Since the parietal bones used for cell isolation derive from neuroectoderm, we also analyzed for expression of the neural markers nestin and β3 tubulin in these colonies. Surprisingly, 90% (45 of 50) of the colonies in the control group expressed neural markers, a frequency not changed by 1,25(OH)2D3 treatment. The current studies demonstrate the global and developmental stage-specific effects of 1,25(OH)2D3 on mesenchymal lineage progenitors, and suggest that the effects of 1,25(OH)2D3 on osteogenesis and adipogenesis in RC populations are mediated, at least in part, by increased recruitment of CFC-O/A, but not CFC-A type precursors.
Microstructure of cement-treated Singapore marine clay
Authors: Kamruzzaman A. H. M. , Chew S. H. , Lee F. H.
Published: May 2006

This paper examines the microstructural behaviour of cement-treated soft Singapore marine clay. The microstructure was investigated using X-ray diffraction, (XRD) scanning electron microscopy, (SEM) mercury intrusion porosimetry, and laser diffractometric measurement of particle size distribution. The XRD analysis of cement-treated clay enables the identification of the formation of cementitious products, namely calcium silicate hydrate (CSH) and calcium aluminium silicate hydrate (CASH). The relative amount of cementitious products (CSH + CASH) is found to increase with increase of the cement content. The fabric of the treated clay changes to flocculated type, comprising clay-cement clusters separated by large intercluster voids with smaller intra-cluster pores, as can be seen from the SEM images of treated clay. This change is more pronounced with higher cement content and prolonged curing time. The flocculation of the clay particles also causes water to be trapped within the clay-cement cluster and increases both the effective size of the particles or cluster and the entrance pore diameter. This understanding clearly helps to explain the observed engineering behaviour of cement-treated clays commonly found in deep cement mixing or jet grouting techniques.

Cet exposé examine le comportement microstructural d'une argile marine tendre de Singapour traitée au ciment. Nous avons étudié sa microstructure en utilisant une diffraction de rayons X, une microscopie électronique à balayage, une porosimétrie à intrusion de mercure et des mesures de diffractométrie laser pour la répartition de dimensions de particules. L'analyse XRD de l'argile traitée au ciment permet d'identifier la formation de produits cimenteux, nommément d'hydrate de silicate de calcium (CHS) et d'hydrate de silicate d'aluminium calcium (CASH). Il est apparu que la quantité relative de produits cimenteux (CSH + CASH) augmentait en même temps que la teneur en ciment. La structure de l'argile traitée devient floculée et comporte des noyaux d'argile-ciment séparés par de grands vides entre les noyaux et avec de pores plus petits à l'intérieur des noyaux. Ce changement est plus prononcé lorsque le contenu de ciment est plus élevé et que le temps de cuisson est plus long. La floculation des particules d'argile a pour effet de piéger l'eau à l'intérieur des noyaux argile-ciment et augmente à la fois la dimension effective des particules ou du noyau et le diamètre de pore d'entrée. Cette constatation aide clairement à expliquer le comportement mécanique observé des argiles traitées au ciment utilisées couramment dans les techniques de mixage profond ou d'injection de ciment.
Improving the performance of circular foundations using structural skirts
Authors: Al-Aghbari M. Y. , Mohamedzein Y. E.-A.
Published: May 2006

This paper presents the results of an experimental study on the behaviour of circular foundations with a structural skirt resting on sand. The structural skirts are fixed to the perimeter of the foundations, and can be used for new or existing shallow foundations. The test results indicate that this type of reinforcement increases the bearing capacity of subgrades and modifies the load–displacement behaviour of the footing. Skirt factors are proposed that take into account the variables that affect the bearing capacity, and they are used within the general bearing capacity equation for shallow circular foundations on sand. Also it was found that the structural skirts reduce the settlement of surface footings compared with footings without structural skirts. At a working stress equal to 50% of the ultimate bearing capacity, the settlement of a surface footing can be reduced to just 11% of that for a footing without a structural skirt.

Cet exposé présente les résultats d'une étude expérimentale sur le comportement de fondations circulaires ayant une jupe structurale reposant sur le sable. Les jupes structurales sont fixées sur le pourtour des fondations et peuvent être utilisées pour les fondations peu profondes qu'elles soient en cours d'installation ou déjà installées. Les résultats des essais indiquent que ce type de renfort augmente la capacité porteuse des fonds de forme et modifie le comportement de charge-déplacement de l'assise. Nous proposons des facteurs de jupe qui prennent en compte les variables qui affectent la capacité porteuse; ces facteurs sont utilisés dans l'équation générale de capacité porteuse pour les fondations circulaires peu profondes sur le sable. Nous avons également trouvé que les jupes structurales montrent un affaissement des assises en surface inférieur à celui des assises sans jupes structurales. Avec une contrainte de travail égale à 50% de la capacité porteuse ultime, l'affaissement d'une assise de surface représente seulement 11% de celle d'une assiste sans jupe structurale.
Geotechnical properties of ballast and the role of geosynthetics in rail track stabilisation
Authors: Indraratna B. , Khabbaz H. , Salim W. , Christie D.
Published: May 2006

The ballast and its engineering behaviour have a key role in governing the stability and performance of railway tracks. The deformation and degradation behaviour of ballast under static and dynamic loads was studied based on large-scale triaxial testing. The possible use of different types of geosynthetics to improve the performance of fresh and recycled ballast was also investigated. The research findings showed that the inclusion of geosynthetics improves the performance of ballasted tracks.

Le ballast et son comportement mécanique ont une influence importante sur la stabilité et la performance des voies ferrées. Nous avons étudié le comportement de détérioration et de déformation du ballast sous charge statiques et dynamiques en nous basant sur des essais triaxiaux à grande échelle. Nous avons également étudié la possibilité d'utiliser divers types de géosynthétiques pour améliorer la performance du ballast neuf et recyclé. Les résultats de cette recherche ont montré que l'adjonction de géosynthétiques améliorait la performance des voies ballastées.
Acid-Sensitive Aluminosilicates: Dissolution Kinetics and Fluid Selection for Matrix-Stimulation Treatments
Authors: Hartman R. L. , Lecerf B. , Frenier W. , Ziauddin M. , Fogler H. S.
Published: May 2006

Dissolution kinetics of analcime (a zeolite), chlorite, and illite (layered aluminosilicates) are examined in hydrochloric and mixtures of hydrochloric and hydrofluoric acid systems. Dissolution kinetics were determined from batch reactor experiments in the temperature range of 25 to 100°C. The reaction progress was monitored by analysis of Al, Si, Fe, Mg, and Na concentrations in the aqueous phase. The reactivity of these aluminosilicates was compared with that of kaolinite under similar experimental conditions.

Models for the reaction of the aluminosilicates with each acid are presented. The reaction kinetics incorporated into a geochemical simulator predict matrix-stimulation results for formations containing these minerals. Guidelines for design of matrixstimulation treatments for acid-sensitive formations are formulated.
High Strength, Ultralightweight Proppant Lends New Dimensions to Hydraulic Fracturing Applications
Authors: Rickards Allan R. , Brannon Harold D. , Wood William D. , Stephenson Christopher J.
Published: May 2006

Since the earliest fracturing treatments more than 50 years ago, many different materials have been used including sand, glass beads, walnut hulls, and metal shot. Today's commonly used proppants include various sands, resin-coated sands, intermediate-strength ceramics, and sintered bauxite—each employed for its ability to cost-effectively withstand the respective reservoir closure stress environment. As the relative strength of the various materials increases, so too have the respective particle densities, ranging from 2.65 g/cm3 for sands to 3.4 g/cm3 for the sintered bauxite. Unfortunately, increasing particle density leads directly to an increasing degree of difficulty with proppant transport and a reduced propped-fracture volume for equal amounts of the respective proppant, thereby reducing fracture conductivity. Intuitively, one expects that a lesser-density proppant would be easier to transport, allowing for reduced demands on the fracturing fluids, and if it had sufficient strength, would provide increased width, and hence, enhanced fracture conductivity.

Previous efforts undertaken to employ lower-density materials as proppant have generally resulted in failure because of insufficient strength to maintain fracture conductivity at even the lowest of closure stresses (1,000 psi). Recent research on material properties has at last led to the development of an ultralightweight (ULW) material with particle strength more than sufficient for most hydraulic fracturing applications. The current ULW proppants have apparent specific gravities of 1.25 and 1.75 g/cm3. Laboratory tests will demonstrate exceptional fracture conductivity at stresses to 8,000 psi. This paper presents data illustrating the performance of the new ULW proppant over a broad range of conditions and a discussion of relative performance in field applications.
Production and Injection Profiling Through Permanent-Downhole-Pressure-Gauge Recording During a Coiled-Tubing-Conveyed Workover Operation
Authors: Ouyang Liang-Biao , Sawiris Ramzy
Published: May 2006

Production and injection profiling through permanent-downhole-pressure-gauge (PDG) recording during a coiled-tubing (CT) -conveyed workover operation, a novel and unique application, has been proposed in the present paper. Theoretical development of the new technique is provided first. Example studies are then given to illustrate the application of the technique. Application scenarios, practical issues, and key impacting parameters have also been addressed. Finally, a field case study implementing the new technique for a long horizontal well has been performed to demonstrate how the production profiles calculated from PDG data compare closely to the results from a recent production logging survey, which was expensive and mechanically risky yet turned out to be unsatisfactory.

The technique could be applied to real-time production and injection profiling for different well configurations (vertical, horizontal, deviated, and multilateral) and bring tremendous financial benefits through replacing conventional production-logging surveys that could be cost-extensive for horizontal or multilateral wells offshore.
Optimizing Fracture Stimulation Using Treatment-Well Tiltmeters and Integrated Fracture Modeling
Authors: Mayerhofer Michael J. , Stutz H. Lloyd , Davis Eric J. , Wolhart Stephen L.
Published: May 2006

This paper covers the optimization of hydraulic fracture treatments in a new coalbed methane (CBM) reservoir in Wyoming. A mul-tiwell pilot project was conducted in the Copper Ridge (CR) field to assess future development potential. Hydraulic fracture mapping was successfully performed with treatment-well tiltmeters on six wells including the first-ever used on propped treatments. The mapped fracture height was then used to calibrate the fracture model, perform on-site fracture-design changes, and optimize future fracture treatments. This paper shows how early use of fracture diagnostics can assist in the development of a new reservoir.
A New, Improved JSA Process Gets Enthusiastic Approval From Field Personnel
Authors: Veley Carl , Ritchie Norman , Coats E. Alan , Disatell Joel
Published: May 2006

Many oilfield companies require field crews to systematically analyze safety aspects of their activities before starting work. Most commonly, this process is called a job safety analysis, or JSA.

Recent developments in measuring safety performance have changed the JSA process by better defining its function, as explained in this paper. This change provides major improvements and is rapidly gaining acceptance throughout the Gulf of Mexico petroleum industry.

An informal survey of Gulf of Mexico offshore production facilities and drilling rigs showed that JSAs tend to be viewed as a tedious formality that crews comply with only because they are required to do so. For a typical jackup drilling rig, adopting the new JSA process and its standards can reduce the total time spent in JSA meetings from approximately 30 man-hours per day to fewer than 4 man-hours per day. In general, work crews enthusiastically approve of the new style of JSA because of the time savings and because it clarifies key responsibilities. Where conventional JSAs simply identify things that should happen, the new style causes things to happen, and the result is a considerable reduction in the likelihood of accidents.
Measurement and Prediction of Salt Solubility in the Presence of Hydrate Organic Inhibitors
Authors: Masoudi R. , Tohidi B. , Danesh A. , Todd A. C. , Yang J.
Published: May 2006

Organic inhibitors (e.g. methanol, ethanol, ethylene glycol, and triethylene glycol) are generally used to reduce the risk of gas hydrate formation in drilling and production operations. The addition of organic inhibitors has a significant adverse effect on the solubility of salts, increasing the risk of salt deposition. A better understanding of salting-out problems is necessary for effective design and implementation of flow assurance strategies in such complex systems.

In this paper, we present an experimental investigation on the effect of methanol, ethanol, and ethylene glycol on the solubility of several salts, including halite, sylvite, and antarcticite. The results show that ethylene glycol has a much lesser adverse impact on salt deposition than methanol and ethanol. The details of an experimental setup used for measuring salt solubility and salting out are described. The setup could also provide valuable information on the effectiveness of various inhibitors used for preventing salt deposition in the presence or absence of gas hydrate organic inhibitors.

In addition, a novel predictive numerical approach is proposed to model salt formation in brine solutions with or without hydrate organic inhibitors. The model is based on the equality of the fugacity of salt in the solid phase and aqueous phase, which are calculated by an equation of state. The validity of the new developed model is demonstrated over a wide temperature range (i.e., −20 to 125°C), salt concentration up to saturation point, and hydrate inhibitor concentration up to 50 mass%.
An Analytical Model of Temperature and Stress Fields During Cold-Water Injection Into an Oil Reservoir
Authors: Kocabas I.
Published: May 2006

A new transient analytical model has been developed to study the temperature and stress distribution induced by nonisothermal fluid injection, particularly conventional waterflooding. In the model, the transient pressure, temperature, and stress fields are computed consecutively. The pressure field has been computed by using either the exponential integral solution for a unit mobility ratio displacement or Ramey's composite reservoir model for a nonunit mobility ratio pistonlike displacement. The transient temperature field has been computed by using a model that can account for both the overburden heat losses and transversal heat dispersion within the reservoir. The stress distribution has been calculated with a method presented for a plane strain in a hollow cylinder.

The results implied that the thermoelastic changes in the cooled zone could affect the surrounding stress fields in a profound manner. For instance, for a porous medium with stiff material (such as carbonate reservoirs) owing to cooling by the injected cold water, large-scale tensile stresses arise and may induce new fractures (or propagate existing ones) far into the reservoir. In addition, a major tangential stress concentration develops just in front of the cooled zone; hence, shear yield is highly likely to occur ahead of the thermal front.

The 2D treatment of the temperature field makes the new method superior to the previous analytical models where only a 1D field has been used.
Development and First Field Application of a Gel/Cement Water-Shutoff System
Authors: van Eijden Jip , Arkesteijn Fred , Akil Ihab , van Vliet Jacques , van Batenburg Diederik , McGinn Paul
Published: May 2006

Water production in northeast Syria has increased significantly in recent years. As a result, costs per barrel of oil have increased and the field's production is currently constrained by the facilities capacity.

Production logging tool (PLT) surveys, combined with a reservoir study, showed that good-quality sands were not properly swept by the water, probably because of poor connectivity in the reservoir. It was anticipated that these unswept sands could contribute to production if the watered-out sands were shut off.

A newly developed gel/cement has been used to shut off the watered-out sands in a cost-effective manner. The gel/cement system combines the properties of two shutoff techniques:

Cement for mechanically strong perforation shutoff. Gel for excellent matrix shutoff.

The gel, used as "mix water" of the cement, will be squeezed into the matrix, creating a shallow matrix shutoff. The cement will remain in the perforation tunnel as a rigid seal. This system showed superior shutoff performance in the laboratory compared to normal cement squeeze techniques. Selective perforation of the hydrocarbon zones will re-establish the oil production. The shutoff zones can be reopened later in the well's life when artificial lift has been installed.

The system was tested in the field in two wells. In the first field trial, 84 m of perforations (gross) was squeezed off with the gel/cement in a single attempt. After reperforation of the top and the middle zone, the well produced at a strongly reduced water cut (i.e., 25 to 33% compared with 60 to 62% before the treatment) and an increased oil production (i.e., 3,000 BOPD compared with 1,000 BOPD before the treatment). The oil production declined to 2,000 BOPD over a year; the water cut gradually increased over that period to 56%. In the second well, full shutoff was achieved but oil production could not be resumed for reasons that are not fully understood.
Flow in Perforated Pipes: A Comparison of Models and Experiments
Authors: Clemo Tom
Published: May 2006

A model of pressure losses in perforated pipes that includes the influence of inflow through the pipe walls compares favorably with past and recent experimental studies. The single-phase model was developed in 1987, but it is not generally known in the petroleum industry. This model is compared to three experiments: one using air and two using water. The model must be manipulated to conform with the way individual experimenters report their findings. In general, there is good agreement. Where there is poor agreement, the cause may be experimental artifacts. A second model fails to match experimental results when the pipe geometry changes significantly.
Flow Profiling by Distributed Temperature Sensor (DTS) System—Expectation and Reality
Authors: Ouyang Liang-Biao , Belanger Dave
Published: May 2006

Permanent downhole monitoring can provide valuable information for production decisions in real time without the need to perform an intervention to collect data. One of the commercial permanent monitoring technologies is the fiber-optic DTS, which can record the wellbore temperature profile in real time with decent accuracy and resolution. A key potential application for DTS data is to profile injection or production for wells, which is the primary motivation and focus of this project.

In the present paper, a thermal model recently developed for single-phase-and multiphase-fluid flow along a vertical, deviated, or horizontal well will first be briefly described. The model can be applied for both wellbore temperature prediction (forward modeling) and for flow profiling using a measured temperature profile (inverse problem).

The model has successfully been applied for investigating key thermal characteristics of single-phase- and multiphase-fluid flow along a wellbore. In particular, the dependence of wellbore temperature upon phases, flow profile, fluid type, fluid properties, well deviation, and Joule-Thomson effect will be demonstrated in the paper. The model has further been adapted for directly predicting production and injection profiles (i.e., flow profiling) based on a given wellbore temperature profile. The potential impact of noise in the DTS measurement on flow profiling has been explored.

It is found that the wellbore temperature does not change significantly along horizontal or near-horizontal sections because of the small variation in geothermal temperature. Therefore, based only on steady-state DTS data, the amount and the location of each fluid entry would be difficult to identify. The current study shows that a maximum wellbore deviation of 75° should be honored to appropriately estimate flow profile directly through steady-state DTS data. The study has also led to an observation that under certain circumstances such as multiphase flow, a production profile may be determined through DTS temperature measurement with extra data or information provided. The types of the extra measurements and the appropriate approaches will be recommended.
Compressed Natural Gas (CNG): An Alternative to Liquefied Natural Gas (LNG)
Authors: Economides Michael J. , Sun Kai , Subero Gloria
Published: May 2006

Natural gas is rapidly becoming an even more important resource of energy, with its share in the world consumption expected to increase dramatically over the next two decades. Currently, natural gas is transported to the markets by pipelines as LNG. Transporting the natural gas by pipelines is convenient and economically attractive onshore. For the offshore transport of natural gas, pipelines become challenging as the water depth and transporting distance increase. LNG, an effective means of transporting gas for long distances across the seas, constitutes 25% of the world gas movement. But LNG projects require large investments, along with substantial natural-gas reserves, and are economically viable for distances of 2,500 miles and beyond.

CNG provides an effective way for shorter-distance transport. The technology is aimed at monetizing offshore reserves that cannot be produced because of the unavailability of a pipeline or because the LNG option is very costly. Technically, CNG is easy to deploy, with lower requirements for facilities and infrastructure. "Coselle" and "Votrans" are two would-be commercial, high-pressure gas-storage and -transport technologies for CNG. Technical and economic analyses of these two technologies were done in this study, and a comparison is provided. The results show that for distances up to 2,500 miles, natural gas can be transported as CNG at prices ranging from U.S. $0.93 to $2.23 per MMBtu compared to LNG, which can cost anywhere from $1.5 to $2.5 per MMBTU depending on the actual distance. At distances beyond 2,500 miles, the cost of delivering gas as CNG becomes higher than the cost for LNG because of the disparity in the volumes of gas transported with the two technologies.
Cleanup of Oil Zones After a Gel Treatment
Authors: Seright R. S.
Published: May 2006

A simple mobility-ratio model was used to predict cleanup times for both fractured and unfractured production wells after a gel treatment. The time to restore productivity to a gel-treated oil zone (1) was similar for radial vs. linear flow, (2) varied approximately with the cube of distance of gel penetration, (3) varied inversely with pressure drawdown, (4) varied inversely with the kw at Sor in the gel-treated region, and (5) was not sensitive to the final ko at Swr. Although ko at Swr (after gel placement) had no effect on the cleanup time, it strongly affected how much of the original oil productivity was ultimately regained.
Deep Downhole Chemical Injection on BP-Operated Miller: Experience and Learning
Authors: Wylde J. J. , Williams G. D. M. , Careil F. , Webb P. , Morris A.
Published: May 2006

The BP-operated Miller field poses a unique chemical challenge because it has arguably the harshest oilfield scaling regime in the North Sea, if not the world. An average of three to four squeeze treatments per week are performed across the online wells, creating tremendous operational, chemical, and logistical challenges. This produces the ideal environment in which to evaluate new technologies and engineering solutions in an attempt to increase the wells’ overall efficiency.

Deep downhole chemical injection (DDHCI) was installed on Well A26/08 and brought on line in July 2003. The Miller DDHCI is unique to the industry because it allows the injection of a scale inhibitor at the perforations by means of a tail pipe, essentially protecting the whole of the tubing from scale deposition. This approach has the potential to reduce the need for additional scale control through squeeze treatments.

Much emphasis has been placed on the efficiency of scale protection that DDHCI offers. A year of flowing the well under the protection of the continuous-injection chemical has yielded much information about the nature of the chemical delivery and inhibitor efficiency. Much also has been learned about the pumping hardware required to ensure continued performance. Further information has been provided by two intensive sampling exercises that have allowed independent analysis of the squeeze chemicals and the injected chemical.

This paper details the design criteria of the DDHCI completion as well as the philosophy of installing such a device. It then gives details on the management strategy of using DDHCI in a proactive manner to maximize the time between squeeze treatments.
Stabilization of Gas-Distribution Instability in Single-Point Dual Gas Lift Wells
Authors: Eikrem Gisle Otto , Aamo Ole Morten , Foss Bjarne A.
Published: May 2006

While casing-heading instability in single gas lift wells has attracted a lot of attention, gas-distribution instability in dual gas lift wells has not. In this paper, we present a simple, nonlinear dynamic model that is shown to capture the essential dynamics of the gas-distribution instability despite the complex nature of two-phase flow. Using the model, stability maps are generated showing regions of stable and unstable settings for the production valves governing the produced flows from the two tubings. Optimal steady-state production is shown to lie well within the unstable region, corresponding to a gas distribution between the production tubings that cannot be sustained without automatic control. A simple control structure is suggested that successfully stabilizes the gas-distribution instability in simulations and, more importantly, in laboratory experiments.
Hydrologic and Vegetation Effects on Water Column Phosphorus in Wetland Mesocosms
Authors: White J. R. , Reddy K. R. , Majer-Newman J.
Published: May 2006

Historic phosphorus (P) loading from agricultural areas has been identified as one of the major causes for ecological changes occurring in the Florida Everglades. The restoration plan for the Everglades includes construction of large stormwater treatment areas (STAs) to intercept and treat this relatively high nutrient water down to very low total P (TP) concentrations. One such STA has been in operation for approximately 10 yr and contains both emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV) communities. The surface water TP concentrations in areas near the outflow range from 0.02 to 0.05 mg TP L−1 To simulate these areas, we investigated the interaction of vegetation type; EAV or SAV; and hydrology; continuously flooded or periodic drawdown; on the P removal capacity in mesocosms packed with peat soil obtained from STA‐1W. The surface water had low TP concentrations with an annual mean = 0.023 mg L−1 For SRP and TP, hydrologic fluctuations alone had no discernable impact on P treatment while vegetation type showed a significant impact. Influent soluble reactive P (SRP) decreased by 49% for the SAV treatments compared with 41% for the EAV treatments, irrespective of hydrology treatment. The reduction of dissolved organic P (DOP) was also higher for the SAV treatment averaging 33% while showing a reduction of 11% for the EAV treatments. There was no significant difference in the treatment efficiency of particulate P (PP) across the treatments. For TP, SAV treatments removed 45% of TP while EAV removed significantly less at 34%. By mass calculations, the EAV required 85% more P for plant growth than was removed from the water column in 1 yr compared with only 47% for the SAV. Therefore, the EAV “mined” substantially more P from the relatively stable peat soil, translocating it into the detrital pool.
Short‐term Effects of Sewage‐Sludge Compost on a Degraded Mediterranean Soil
Authors: Larchevêque Marie , Baldy Virginie , Montès Nicolas , Fernandez Catherine , Bonin Gilles , Ballini Christine
Published: May 2006

In Mediterranean areas, often characterized by degraded soil due to recurrent fires and violent precipitation events, sewage sludge compost could improve soil properties and stimulate plant succession processes. Most of the studies dealing with compost effects on soil properties only take into account the mineral horizon compartment, without studying compost effects on organic horizon properties. In this study, we monitored the patterns of change in the litter, humus, and mineral horizon compartments in a 7‐yr‐old garrigue over 2 yr after compost spreading. Three treatments were studied: control, 50 Mg ha−1, and 100 Mg ha−1(Fresh Mass) of cocomposted sewage sludge and green wastes. The major changes occur in the humus and litter compartments, whereas the mineral horizon is slightly affected. The mineral horizon is enriched in exchangeable K, Mg, and sporadically in P (total and available) after amendment, slightly improving overall fertility, while the humus and litter compartments keep accumulated compost organic matter and its associated nutrients, showing the slow release of elements from the chosen mature compost. Compost amendment probably enhances the humus decomposition process, first because it decreases this compartment's C/N ratio, and second because it decreases its Ni and Cr concentrations. In contrast to humus, compost should reduce the litter decomposition process, by increasing C/N ratio, pH, and concentrations of potentially toxic trace elements such as Cu, Zn, Ni, Cr, and Pb. Compost greatly enriched humus and litter in P, Cu, and Zn, and only Cu moves from organic to mineral soil horizon.
Impact of Tillage and Residue Burning on Carbon Dioxide Flux in a Wheat–Soybean Production System
Authors: Brye Kristofor R. , Longer David E. , Gbur Edward E.
Published: May 2006

Burning of wheat (Triticum aestivum L.) residue followed by plowing is a common management practice in wheat–soybean [Glycine Max (L.) Merrill] production systems in the mid‐southern USA. However, this residue management practice is not environmentally friendly and may not be sustainable. The objectives of this study were to (i) evaluate the effects of N fertilization of wheat, residue burning, and tillage on soil surface carbon dioxide (CO2) flux in a wheat–soybean double‐crop production system, and (ii) evaluate the role of soil temperature and soil moisture in controlling CO2 flux in a relatively warm, subhumid environment. Soil surface CO2 flux was measured nine times between June 2002 and October 2003 during the soybean growing season under all combinations of conventional‐ (CT) and no‐tillage (NT) at high and low N fertilization levels with and without residue burning at two locations in the Mississippi River delta region of eastern Arkansas. Soil surface CO2 flux was 37.6% higher (P < 0.01) from CT than from NT and 6.1% higher (P < 0.05) from the low than the high N rate treatment at one location, but not at the other. Burning did not affect soil surface CO2 flux except for a significant burning × N rate (P = 0.016) and burning × time interaction (P = 0.032) at one location, but not at the other. Both soil temperature and moisture parameters were significantly negatively correlated with temperature‐normalized soil surface CO2 flux, but soil temperature, particularly at the 10‐cm depth, explained more of the variation than did soil moisture parameters. The results of this study indicate that tillage and N fertilization of prior wheat, but not residue burning, affect the loss of C as CO2 from the soil and that there are additional soil and/or environmental factors, other than near‐surface soil moisture and temperature fluctuations, perhaps microbial biomass, that contribute to controlling soil surface CO2 flux in wheat‐soybean production systems in the subhumid region of southern USA.
Geostatistical Tools for Characterizing the Spatial Variability of Soil Water Repellency Parameters in a Laurel Forest Watershed
Authors: Regalado C. M. , Ritter A.
Published: May 2006

Soil water repellency is recognized to be a widespread phenomenon which may affect a wide range of spatially dependent hydrological processes that take place in the vadose zone such as infiltration, preferential flow, and soil water distribution. Despite this, the spatial structure of soil repellency has received almost no attention in the past. The objective of this study is to investigate the spatial variability of water repellency in the top horizon of a laurel forest watershed. Water repellency was measured with the molarity of an ethanol droplet (MED) test, from saturation to oven‐dry, in 140 soil samples taken in a nested structure that encompasses both short (centimeter scale) and long (meter scale) distances. Geostatistical tools such as correlograms and kriging were used to quantify the spatial structure of soil organic matter (SOM) content and the parameters that characterize the water repellency curve. Both showed characteristic spatial trends, and, in general, spatial correlation followed a spherical, exponential, or gaussian model. All parameters investigated exhibit scale dependence, in particular, variability of SOM and the area below the repellency curve point toward a self‐similar fractal scaling. Cross‐correlation of some of the repellency parameters and SOM was not random but showed spatial structure.
Soil Nutrient Dynamics after Harvesting and Slash Treatments in Boreal Aspen Stands
Authors: Belleau A. , Brais S. , Paré D.
Published: May 2006

The effects of harvesting and slash treatments on soil nutrient dynamics were assessed in boreal aspen stands growing on mesic clayey sites. Stem‐only harvested stands were compared with unharvested controls according to a complete block design with three replications. Within harvested areas, four slash treatments (stem‐only harvesting [SOH], whole‐tree harvesting [WHT], wood chip application, and slash burns) were compared. Treatments created a gradient of slash that ranged from 52.3 Mg ha−1 in stem‐only to 13.8 Mg ha−1 in control stands. The amount of slash had no effect on wood decomposition rates but was strongly associated with higher forest floor organic C, Kjeldahl N and base cation concentrations (Cae and Mge), base saturation, pH, and effective cation exchange capacity (CEC) and lower microbial C/N when control stands were compared with stem‐only harvested stands. Slash burn severity was too low to significantly reduce slash loads and induce base cation release but severe enough to reduce forest floor microbial C and N concentrations (−48 and −55%, respectively) for at least one complete growing season. Slash burn also induced increases in forest floor available P (54%) concentration compared with other slash treatments. Chipping reduced forest floor microbial N concentration by 25% and increased microbial C/N by 28% but had no impact on nutrient availability. Differences between WTH and SOH were linked to the abundance of slash. Finally, the results illustrate that whatever the treatment, the amount of slash left on the ground is the main factor found to affect soil microbial community characteristics and soil nutrient availability.
Poultry Litter Decomposition as Affected by Litter Form and Rate before Flooding for Rice Production
Authors: Brye Kristofor R. , Golden B. , Slaton Nathan A.
Published: May 2006

Environmentally sound management of poultry litter from concentrated broiler‐producing areas is a major challenge. Due to its chemical composition, poultry litter could be a valuable organic source of plant nutrients and soil amendment for row‐crop agricultural soils if transportation costs are not limiting. However, few studies have investigated the effects of poultry litter on nongraded soils used for rice (Oryza sativa L.) production in the mid‐southern United States. The objectives of this study were to evaluate the effect of poultry litter form (fresh and pelletized) and five application rates (34–269 kg N ha−1) on soil surface CO2 flux, total soil N and organic C, and inorganic soil N before flood establishment and to evaluate the effect of soil temperature and moisture on soil surface CO2 flux in two silt‐loam Aqualfs. Poultry litter decomposition dynamics, as measured by soil surface CO2 flux and total soil N and organic C concentrations in the top 10 cm, were unaffected by litter form but were generally affected by litter rate. When significant, soil surface CO2 flux, total soil N and organic C, and soil NO3–N and NH4–N increased as litter rate increased. Soil NH4–N was generally unaffected by litter form, but soil NO3–N was consistently higher from the pelletized than fresh litter when added between 134 and 269 kg total N ha−1, suggesting that pelletized litter may have a slightly greater fertilizer‐N value than fresh litter. Environmental factors, such as soil temperature and moisture, were not significant controlling factors for soil surface CO2 flux early in the rice growing season, suggesting that soil biological properties such as microbial biomass may be more of a controlling factor than moisture and temperature.
Modeling the Soil Shrinkage and Water Retention Curves with the Same Equations
Authors: Boivin Pascal , Garnier Patricia , Vauclin Michel
Published: May 2006

Recent studies underlined the likeness of soil water retention (WRC) and shrinkage curves (ShC) with respect to their shapes. This paper aims at experimentally discussing the possible use of the same equations to fit them. The WRC (on the tensiometric range) and ShC were simultaneously determined on a series made of 28 undisturbed soil cores collected in surface horizons from a wide variety of soil types, with clay content ranging from 8.5 to 65% and of 30 repacked soil samples of various clay contents and mineralogies. The van Genuchten (VG) closed‐form equation of WRC and the VG modified equation of ShC, with five and three parameters, respectively, were found to fit well to both curves, but they did not properly reproduce the observed linear parts and sloping ends of both curves, and the dissymmetric shapes of the ShC as well. The exponential shrinkage model XP fitted significantly better to both the WRC with five parameters and the ShC with eight parameters. It is shown that the transition points of the XP equations independently fitted on the ShC and WRC curves occur at the same gravimetric water content, thus illustrating the likeness of the curves with respect to their shape. The WRC was estimated with a reasonable accuracy from the water content of the ShC transition points plus some measured suction values.
Wavelet Spectra of Nitrous Oxide Emission from Hummocky Terrain during Spring Snowmelt
Authors: Yates T. T. , Si B. C. , Farrell R. E. , Pennock D. J.
Published: May 2006

Soil N2O emission data is typically highly skewed. In terrain where the spatial distribution of soil processes is controlled by topography, extreme N2O flux events can be highly localized and nonstationary. Wavelet analysis can be used to describe the spatial variation of these nonstationary processes. The objectives of this study were to use wavelet analysis to determine the spatial variation, scales of variability and their change over the snowmelt period for soil N2O flux. On a hummocky, agricultural landscape in the Dark Brown soil zone of Saskatchewan, N2O flux measurements were taken from a 128‐point linear transect five times over the spring snowmelt season of 2004. Localized variance was determined using a continuous wavelet transform (Mexican Hat) and the local spectrum was compared with the distribution of fluxes along the transect and the relative elevation. Two spatial patterns of soil N2O emission were revealed. The first was a cyclic, landscape‐element‐controlled pattern with a scale of variation that ranged between 20 and 60 m. Changes in the spatial scale were due to a shift in importance between landscape elements as sources of peak N2O flux. The second pattern was composed of non‐cyclic, localized features that were due to extreme flux events at specific landscape positions. These extreme flux events were not temporally persistent, but represent a large, non‐random contribution to mean and variance on the dates they occurred. Sample strategies to capture the full range of soil N2O emission at this site would probably require separate approaches for these two spatial patterns.