bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hatch Timing Variations among Reservoir Gizzard Shad Populations: Implications for Stocked Sander spp. Fingerlings
Authors: Zweifel Richard D. , Hale R. Scott , Bunnell David B. , Bremigan Mary T. 
Published: April 2009

Abstract
Growth and survival of stocked Sander spp. fingerlings can be influenced by timing of stocking in relation to the peak in density of larval gizzard shad Dorosoma cepedianum. However, coordinating stockings to coincide with peaks in gizzard shad density is difficult due to temporal variation in spawn timing among reservoirs. We used weekly estimates of larval gizzard shad density and length distributions to identify dates of peak hatching and peak total density in Ohio reservoirs and to explore the influence of spring water temperature regimes on timing of peak larval density. Gizzard shad density peaked over 21–32 d among reservoirs but generally varied by 12 d or less among years for any given population. Density peaks were driven by hatching, as larvae smaller than 10 mm accounted for a majority of the gizzard shad collected on the peak date. Peaks in gizzard shad density corresponded to water temperatures of 17–22°C and occurred most frequently when water temperatures had been stable or rising. Reservoirs in the southern portion of the state were 2–5°C warmer than northern reservoirs throughout the spring; thus, gizzard shad spawning and date of peak larval density were earliest in southern reservoirs and became progressively later for populations in more northerly reservoirs. Historical stocking dates for fingerling walleyes S. vitreus and saugeyes (sauger S. canadensis × walleye) in Ohio reservoirs indicated that southern reservoirs were often stocked after the expected peak in gizzard shad density and northern reservoirs were stocked before the peak. A statewide approach to stocking that incorporates latitudinal variations in gizzard shad hatch timing whereby southern reservoirs are stocked earliest would better align stockings with peak gizzard shad density, potentially improving survival of fingerling walleyes and saugeyes.
Genetic erosion and population resilience in Daphnia longispina O.F. Müller under simulated predation and metal pressures
Authors: Lopes Isabel , Martins Nelson , Baird Donald J. , Ribeiro Rui 
Published: April 2009

Abstract
This study investigated the effects of nonselective predation (culling) and metal toxicity on the genetic diversity of laboratory populations of the cladoceran Daphnia longispina. Populations, comprising five clones differing in their sensitivity to lethal concentrations of a metal-rich mine drainage effluent, were subjected to all possible combinations of three levels (absent, weak, and strong) of each stressor. Observed population densities were compared to those expected from a life history experiment, and clone frequencies were determined by allozyme profiling. Culling did not affect population density, although clonal diversity was higher than the control. Populations stressed by mine drainage recovered to their initial densities within 12 days, though the most sensitive genotypes disappeared under both weak and strong metal stress levels. Because the surviving resistant clones were shown to be the most sensitive ones to other chemicals (Cd and H+), it is suggested that successive inputs of partially lethal concentrations of different chemicals can lead to the disappearance of the population, even if the time between inputs is large enough to allow density recovery. These results suggest that changes in abundance are not enough to evaluate ecological effects of chemicals on the environment and information on co-tolerance and multiple tolerance within populations is highly valuable to prevent their extinction. Moreover, populations exposed to low levels of both stressors showed clonal diversity levels identical to controls, highlighting the importance of low level effects of nonselective stressors in the maintenance of high clonal diversity levels in Daphnia populations, and thus further supporting the intermediate disturbance hypothesis.
Arsenate toxicity for wheat and lettuce in six Chinese soils with different properties
Authors: Cao Qing , Hu Qin-Hong , Baisch Cristoph , Khan Sardar , Zhu Yong-Guan 
Published: April 2009

Abstract
To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination.
Kinetics of the Reaction of Citric Acid With Calcite
Authors: Alkhaldi M. H. , Nasr-El-Din H. A. , Sarma H. 
Published: April 2009

Abstract
The previous studies of citric-calcite have been limited to core flood tests, and bench scale experiments. However, the reaction kinetics of citric acid-calcite has not been measured. This paper gives, for the first time, the kinetics of citric-calcite reaction, which will provide a better way to model the performance of citric acid as a stand-alone stimulation fluid.
In this paper, the rotating disk was used to study citric-calcite reaction at pressure of 1,000 psi, temperature values from 25 to 50°C, citric acid concentrations of 1 to 7.5 wt%, and disk rotational speeds of 100 to 1,000 rpm. The reaction of citric acid with calcite is dependent on the initial citric acid concentration, disk rotational speed, and the temperature value. For example, at 50°C, the reaction is reaction rate-limited at high rotational speeds, rpm &gt; 500, using high initial citric acid concentrations (3, 5, 7.5 wt%), while at low acid concentrations (1,2 wt%), the reaction is mass-transfer limited even at high rotational speeds, 1,000 rpm. Calcium citrate formation is also dependent on both the initial citric acid concentration, and the rotational speed. More calcium citrate forms at high initial citric acid concentrations, especially at high rotational speeds.
Calcium citrate precipitation occurred at the reacted calcite surface, even at low initial citric acid concentration, 1 wt%. Due to this precipitation, the equilibrium of citric-calcite reaction was disturbed, and the reaction shifted towards the forward reaction (toward the products). Therefore, the overall reaction rate was mainly governed by the rate of the forward reaction, and hence, it was molded by a new simplified reaction rate equation, rate = kf {Ka1*CB}n/2. The average value of the reaction order (n) was found to be equal to 0.833. In addition, the value of the reaction constant (kf) was determined at various temperatures. The effect of temperature on the reaction order was found to follow Arrhenius law, where the activation energy was found to be equal to 63.1 kJ/mol.
Re-commissioning of Mothballed Pipelines Offshore California: A Success Story of Cleaning, Pigging, Monitoring and Integrity Management
Authors: Wylde Jonathan J. 
Published: April 2009

Abstract
Three unused intra-field pipelines exist between two platforms in a producing complex located offshore California. The complex produced 2,200 BOE/d and the project was to bring an offline platform online in order to boost production. The platform had not produced since 1999 and the pipelines had not seen active duty since that time.
The major challenge for this project was the condition of the intra-field pipelines and the requirement to provide the US Minerals Management Service (MMS) with a robust integrity management strategy in this environmentally sensitive area of the Pacific Ocean.
This paper gives details on the external pipeline condition as determined by ROV coupled with cathodic potential measurements. Further details are given on how the pipelines were intelligently pigged including the chemical cleaning procedure that enhanced the efficacy of the pigging runs.
The well start-up strategy and a description of the operating conditions of the facilities and pipelines are given. The corrosion mitigation and monitoring strategy form the bulk of discussions. Details are also given on the initial batch treatments to establish a protective chemisorbed film on the pipelines as well as the subsequent maintenance of these films. The discussion of the monitoring strategy includes direct electrochemical monitoring using ER probes in addition to indirect monitoring using amine residuals, iron and manganese counts and corrosion coupons. Final details are given on the successful start up of the platform and pipelines and the success of the integrity management strategy.
The proactive work gave MMS assurance on the continued integrity of the pipeline, protection of production, and of the environment.
A New MIC Control Strategy in Low Velocity Gas Gathering Pipelines
Authors: Smith C. , Li C. , Bedard T. , Kimler J. 
Published: April 2009

Abstract
Internal corrosion related failures in oil and gas gathering systems are increasing, especially in conditions categorized as "low risk" by computer modeling. Such systems usually exhibit, low pressure, low temperature sweet gas production, and relatively low total dissolved solid content waters. The failure rate is commonly influenced by two major factors; 1) undiagnosed microbiologically influenced corrosion (MIC) mechanisms, and 2) the unappreciated impact of corrosive chemical biocides used to treat sessile and planktonic bacteria. Low velocity gas gathering systems are particularly difficult to treat for MIC as a result of pigging challenges and the tendency for corrosive biocides to concentrate in the water phase over time. Here we report a new water soluble quaternary ammonium compound, didecyldimethylammonium bicarbonate/carbonate (DDABC), that acts as an MIC corrosion control agent against common oilfield bacteria. At the proper dilution, DDABC also acts as a thin film forming anodic inhibitor on steel. Supporting lab and field tests indicate this inhibitor is effective in competitive evaluations against glutaraldehyde, THPS, and quaternary ammonium chloride based agents. In a field trial reported herein, DDABC reduced the failure rate of a 1,653 km low velocity gas gathering field to approximately one-sixth the original rate in a 20 month field trial.
An Innovative Cement Formula To Prevent Gas Migration Problems in HT/HP Wells
Authors: Al-Yami A. S. , Nasr-El-Din H. A. , Al-Humaidi Ahmad 
Published: April 2009

Abstract
Gas Migration through cement columns has been an industry problem for many years. The most problematic areas for gas migrations occur in deep gas wells. To control gas migration, cement densities required to successfully cement the zone could be as high as 170 pcf (Pounds per Cubic Foot). As cement slurry sets, hydrostatic pressure is reduced on the formation. During this transition, reservoir gases can travel up through the cement column resulting in gas being present at the surface. The permeable channels, from which gas flows, cause operational and safety problems at the well site.
Current high density cement formulations do not provide good gas migration prevention due to settling and subsequent increase in permeability. To address the settling problem and reduce permeability of cement, a formula that resulted in great gas prevention was developed.
A gas migration set-up helped in testing and optimizing cement formulations to measure gas flow through cement columns. The gas migration set up consisted of the following components: computer, data acquisition, full-length permeability determination, two partial length permeability determinations, cement volume change measurement, gas flow meter, and electronic filtrate weight determination. The pressure and temperature limitations are 2,000 psi maximum and 350°F. Different chemicals for gas migration prevention were evaluated. Special types of cements were designed and evaluated for possible use for cementing gas wells. Addition of inert particles to cement and their effect on gas migration prevention was investigated.
In this paper, a new cement system was developed and resulted in significant gas prevention. The performance of this system outperforms available formulations and has great potential to improve wellbore isolation in deep gas wells.
Low Dosage, High Efficiency and Environment Friendly Inhibitors: A New Horizon in Gas Hydrates Mitigation in Production Systems
Authors: Kannan Krupa , Punase Aarti 
Published: April 2009

Abstract
Presently, gas hydrates formation pose problems, causing flow restrictions, in gas and oil industry including drilling operations (particularly in deep water), production process, well workovers where gas and water come into contact at equilibrium conditions. Traditional hydrate control methods of insulation and/or thermodynamic or chemical inhibition may not provide the desired level of hydrate protection at an economic price. Low-Dosage Hydrate Inhibitors (LDHIs) are a proven technology to control hydrates in numerous applications and are instrumental in reducing the total cost of operations. Low dosage Inhibitors are either kinetic, thermodynamic inhibitors or anti- aglomerants, which either prevent hydrate formation or remove the hydrates that are already formed respectively.
Therefore, this paper focuses on introduction to such low dosage inhibitor which can perform all the functions like prevention of formation of hydrate nuclei (like kinetic or thermodynamic inhibitors) and dispersing the already formed ones in flowlines (like anti- agglomerants). This paper proposes the use of Cationic polymers like cationic starch (from a high amylose carbohydrate source) in low concentration with addition of Polyethylene Oxide (PEO) as a new Gas Hydrates inhibitor.
The polymer with PEO, dissolved in water, can be introduced in petroleum fluid using mechanical equipment or utilized in treating fluid prior to substantial formation of the hydrates. As observed from an experimental analysis, these positively charged polymers interfere with nucleation of hydrates, increase induction time of gas hydrate nucleation, suppress memory effect, and act as antifreeze and thereby controlling hydrates.
With reference to these polymers, their abundant availability, easy application techniques and simple cationization procedure all contribute to its inexpensive and environment friendly usage as gas hydrate inhibitor. This paper provides systematic approach and relevant theoretical explanation for the proposed technique.
Successful Field Application of a High-Temperature Conformance Polymer in Mexico
Authors: Mercado Modesto , Acuna Juan Carlos , Caballero Carlos , Vasquez Julio , Soriano Eduardo 
Published: April 2009

AbstractConformance-polymer systems have been successfully applied for many years to control undesired water production from hydrocarbon wells. However, currently available polymers present a number of limitations for high-temperature wells (&gt;250°F) in terms of providing longer gelation times and acceptable thermal stability. This paper presents the successful field implementation of an organically crosslinked polymer (OCP) for high-temperature applications in southern Mexico.The OCP system is based on a copolymer of acrylamide and t-butyl acrylate (PAtBA) crosslinked with polyethyleneimine (PEI). To date, more than 450 jobs have been performed with the OCP system around the world to address conformance problems, such as water coning/cresting, high-permeability streaks, gravel pack isolation, fracture shutoff, and/or casing-leak repair. Originally, the OCP system had a limited working temperature range from 100° to 250°F. The upper placement temperature of the system was ~250°F because, above this temperature, pumping times were too short. A recently developed carbonate retarder allows reasonable placement times up to 350°F, without the need for cooling down the formation to obtain enough pumping time. The retarder is not detrimental to the thermal stability of the system.An overview of case histories that used OCP in southern Mexico is presented in this paper. In addition, the development results of the high-temperature conformance polymer are discussed in terms of (1) gelation-time measurement and (2) effectiveness to limit permeability to water and thermal stability in sandpack flow tests at elevated temperatures. To date, more than 70 jobs have been successfully performed worldwide with the OCP at temperatures higher than 250°F.
Prevention of Vertical Gas Flow in a Collapsed Well Using Silicate/Polymer/Urea Method
Authors: Lakatos Istvan , Medic Borimir , Jovicic Dragan , Basic Ivan , Lakatos-Szabo Julianna 
Published: April 2009

Abstract
The overpressurized CO2 field Becej (Serbia) was found in 1951. At the end of 1968, drilling a well, an uncontrolled gas blowout happened and lasted for 209 days. The disaster claimed human lives and huge gas loss until it was spontaneously killed by collapse of the well5. Hence, the substantial loss of reserve (&gt;17 billion m3) became critical and urgent actions had to be taken to stop the vertical gas migration. As a precondition, environmentally friendly chemicals could be used for restriction of vertical gas flow in the collapsed well. Therefore, silicate solution aided by polymer and urea was recommended for the job utilizing its auto-gelation in CO2 rich media. The triangle well pattern was the basis of operation consisting of an observation and a newly drilled directional well that served for injection of the treating solutions. The inverted injection protocol and huge volume of treating solution jointly proved satisfactory to provide extensive pillow around the well filling up also the accumulated debris at the bottom and open vertical hole. Restriction of vertical CO2 migration in and around the collapsed well was successfully completed in the middle of 2007. As a result of treatment, the annual decline of formation pressure was merely 0.03 bar/y compared to 0.9 bar/y before the treatment. Further, other indications in the damaged and the observation wells have shown that the uncontrolled gas flow was considerably restricted or completely stopped. The successful restriction of gas migration into the upper layers (and the atmosphere) preserves the CO2 reserve, limits CO2 and GHGs emission to atmosphere and stabilizes the collapsed well against potential danger of repeated gas blowout.
Identification and Analysis of Biocides Effective Against Sessile Organisms
Authors: Keasler Victor , Bennett Brian , Diaz Raul , Lindemuth Paul , Kasowski Dale , Adelizzi Craig , Santiago-Vazquez Lory Z. 
Published: April 2009

Abstract
Microbiologically influenced corrosion (MIC) is a major problem in the oil and gas industry. Although the exact mechanism by which this occurs is not well understood, it is recognized that byproducts produced by sessile bacteria located on the metal surface are responsible for the corrosion. However, many of the biocide treatment programs that have been developed thus far have focused only on planktonic organisms, ignoring the root cause of the problem. The goal of this research was to develop and implement sessile monitoring and analysis capabilities to assist in biocide selection.
Initial laboratory testing was performed using a representative selection of bacteria inoculated into a closed flow loop system containing removable biostuds. Sessile bacteria populations were analyzed before and after biocide treatment using serial dilutions and denaturing gradient gel electrophoresis (DGGE). A biocide/surfactant combination shown to be effective in the lab was tested in a field trial to demonstrate a correlation between laboratory testing and field use. Data collected in the field was analyzed by quantitative PCR (qPCR) as well as DGGE.
The biocide/surfactant tested in the laboratory led to a 3-log reduction in sessile bacteria without regrowth 24 hours after treatment. Bacterial enumeration determined by serial dilution was confirmed by DGGE analysis. This biocide/surfactant combination was also tested in a field trial where a 3- to 5-log reduction in bacterial numbers was determined by qPCR, a dramatic reduction in bacterial species observed by DGGE, and reduced pitting of the corrosion coupons identified.
In conclusion, we have implemented new testing capabilities that allow us to identify biocides effective at removing sessile organisms in the laboratory. Importantly, we have also shown that these laboratory results are recapitulated in field trials. These methods can now be utilized to ensure that the most efficacious biocide is chosen to mitigate bacterial populations that could potentially cause MIC in an asset-specific manner.
Reaction of CO2 With Portland Cement at Downhole Conditions and the Role of Pozzolanic Supplements
Authors: Santra Ashok , Reddy B. R. , Liang Feng , Fitzgerald Rocky 
Published: April 2009

Abstract
Interaction between Portland cement and carbon dioxide has attracted much renewed interest because of its implication in geological sequestration of CO2. The fundamental interaction and mechanism have been extensively studied in the literature under ambient conditions. These studies demonstrate that the rate of carbonation is a function of many factors. Examples include: cement type, moisture content, CO2 partial pressure, porosity/permeability, and temperature. Many remedies have also been proposed to counteract such carbonation. However, extrapolating such data to understanding the behavior of carbonation under high pressure and temperature (HPHT) conditions is not trivial. Very recently, attempts have been made by other researchers in the field to understand kinetics of HPHT carbonation. This paper discusses the results obtained on cement specimens treated under water at 200°F and 2,000 psi CO2 pressure for several weeks. As part of this study, we have also very carefully investigated the role of pozzolanic substitution (silica fume and fly ash at various degrees of substitution) in Portland cement blends. Analytical techniques used for characterization included: thermal gravimetric analysis (TGA), Brinell hardness, and X-ray diffraction. The results show that the depth of carbonation during a period of up to 15 days at a given temperature and pressure is directly proportional to the amount of pozzolanic supplement. The results will provide insight into designing cement slurries resistant to carbonation.