bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Wavelet Transform in Pressure-Data Treatment
Authors: Ribeiro P. M. , Pires A. P. , Oliveira E. A. P. , Ferroni J. G. 
Published: February 2008

Summary
Since the beginning of the 1980s, more downhole pressure gauges (DPGs) were installed in production and injection wells. The main purpose was well monitoring and evaluation of reservoir performance. This kind of gauge provides a large amount of data, but there are various problems that do not allow their complete use. These problems are related to quantity and quality. Most software is not able to handle the main objective for using DPGs with all the data available in a long recording period. Besides that, gauges present noise and strange data (outliers). It becomes necessary to treat the data before its use in the study of reservoir behavior. The concept of wavelet transform (WT) was developed about a century ago, but it was during the 1980s that it received practical application. Now it is used in a wide variety of applications, and, especially in data treatment, it presents two main features that make it attractive: smoothing of the signal and retention of the details. In this paper, we use the WT to overcome the main problems and enhance the reliability of the information contained in the data. We tested different wavelets with several decomposition levels against actual and synthetic data. The outliers must be removed before the wavelet analysis in order to enhance its performance. We show that there is no unique "correct" WT to apply in any flow period. For example, for some data sets the Daubechies 1 wavelet at decomposition Level 6 was used for flow periods, and Level 3 for buildup. It is important to notice that the use of high decomposition levels may cause loss of information, as is shown in some examples. The wavelet analysis was also used to recognize transients from its ability to enhance the details. This is particularly useful to identify flow rate changes when they have not been reported, for example. Finally, we propose a methodology to treat the data before its use in posterior interpretation.
Mechanistic/Probabilistic Modeling of Slug Initiation in a Lower Elbow of a Hilly-Terrain Pipeline
Authors: Al-Safran E. M. , Sarica C. , Zhang H. -Q. , Brill J. P. 
Published: February 2008

Summary
Probabilistic/mechanistic modeling was carried out to develop a predictive model for initiated slug-length distribution at the lower elbow of a hilly-terrain pipeline. Statistical analysis suggested the appropriateness of a Log-Normal model over an Inverse Gaussian model. The Log-Normal model is correlated by two empirical relationships developed for mean slug length and slug-length standard deviation. Based on experimental observations, the approach of critical liquid level (instead of critical liquid volume) was adopted as the slug initiation criterion at the lower elbow. Consequently, the critical liquid level was mechanistically modeled and empirically correlated to the initiated mean slug length and standard deviation. A model validation study demonstrated the capability of the probabilistic/mechanistic models to reproduce experimental data with a satisfactory match. The match is improved when the developed correlations were tuned using the statistical confidence intervals of their coefficients.
Effect of Reservoir Mineralogy and Texture on Acid Response in Heterogeneous Sandstones
Authors: Morgenthaler Lee N. , Zhu Ding , Mou Jianye , Hill A. D. 
Published: February 2008

Summary
A series of coreflood experiments with stimulation fluids [hydrochloric acid (HCl) preflush followed by hydrochloric/hydrofluoric acids (HCl/HF) main flush followed by amonium chloride (NH4Cl) post flush] has been conducted on a suite of cores from several Gulf of Mexico Miocene turbidite reservoirs. Using thin-section petrography and computer tomography (CT) scans, the samples were characterized as more or less heterogeneous. Samples ranged from reasonably homogeneous to highly laminated. Sample mineralogy was assessed by X–ray diffraction (XRD). The quartz content of the cores ranged from 28 to 78%. One core plug contains 39% clay, and the rest of the cores contained between 5 and 18%. These cores also contained between zero and 40% clinoptilolite zeolite. All of these sands are unconsolidated and contain only detrital carbonates. Treatment with HCl was not expected to cause core failure. The only core failure observed occurred during HCl/HF treatment.
Acid response was assessed on the basis of permeability change and effluent chemical analysis, which varied dramatically among the samples. Release of particles was not observed. In the poorer-quality, more-laminated samples, channeling with significant permeability increase was observed during HC1 treatment with little additional change during later stages of the treatment. Selective pore enlargement with little alteration of the matrix framework was observed in post-treatment thin sections. In more-homogeneous sand samples, more-general acid attack was observed. Core effluent indicated carbonate dissolution during the HCl preflush, while HCl/HF attacked alumino-silicates and was roughly half spent during transit through the core. In the homogeneous samples, comparison of thin sections before and after acidization revealed near-complete (greater than 80%) dissolution of carbonate and an extensive "cleaning" of clays and fines from the pore space.
We used a fine-scale simulator of sandstone acidizing to match the responses observed in these experiments. The model corroborates the effects of heterogeneities in the permeability field and in the mineral distribution on the sandstone-acidizing process. These model results show how characterization of fine-scale heterogeneity in sandstone can improve the design of matrix-stimulation treatments.
Implementation of a Total-System Production-Optimization Model in a Complex Gas-Lifted Offshore Operation
Authors: Nadar Manickam S. , Schneider Tim S. , Jackson Kathy L. , McKie Calum J. N. , Hamid Javad 
Published: February 2008

Summary
A total-system production-optimization model has been implemented in a complex gas lifted offshore operation, resulting in production gains and operating-cost reductions. Whereas previous optimization models considered only the wells and production-gathering network, the new model is able to consider the combined performance of the total system, including downhole well configurations, the complex production-gathering and lift-gas-distribution pipeline networks, separators, compressors, and pumps. The model is applicable to most gas lifted fields and will be particularly beneficial when applied to those with complex production systems, and those where compressors are a constraint on total-system performance.
The output from the optimization model principally comprises recommended values for individual-well gas lift injection rates, separator pressures, compressor discharge pressures, and compressor use. Field results are presented in this paper to demonstrate how implementing the optimizer's recommendations in the field resulted in economic benefits through increased production and reduced operating costs. Also described is how the model allows field operations engineers to reoptimize field control parameters on a more frequent basis and with less manpower than previously.
The successful implementation of a complex model with such a broad scope is as dependent on the implementation process as it is on the technology. Therefore, in addition to describing the details of the model itself, this paper will cover the issues that arose during the implementation and how they were resolved. These include the level of manpower and support required, project organization and execution, and the processes required to sustain the benefits after the initial optimization gains have been realized.
Enablers for Successful Implementations of Intelligent Energy: The Statoil case
Authors: Henriquez A. , Fjærtoft I. , Johnsen C. , Yttredal O. , Gabrielsen T. 
Published: February 2008

Abstract
Statoil has implemented a strategy for wide deployment of Integrated Operations (IO), which has evolved on the basis of the company's cultural and organisational characteristics, the experiences it has gained and the assets it operates.
A phase of experimentation, including R&D activities, pilots and wide deployment, was identified as necessary for the understanding of the challenges ahead to mature. Two examples are the development of work processes for production optimization and the design of new wells and drilling with net present value as the main quality criterion.
The second phase was to establish field-specific plans in order to ensure more rapid and broader progress. The third phase recognised that the ambition could be set higher if a concrete vision was established: "to strengthen decision-making onshore and strengthen execution offshore". In addition, IO synergies were identified across assets.
One success factor has been the wholehearted support of senior management, the CEO and the E&P senior vice president and his team. Another factor has been the change management process, which was established through a core team consisting of both discipline and asset expertise, with the formal support of the technical and administrative organisations
The empowerment of the assets and their multidisciplinary groups to develop and implement a broad set of initiatives has been crucial. It provided the enthusiasm, experience and confidence required to make the transition to company-wide solutions.
The impact on the bottom line is already being felt: in 2006, the production increase as a resulted of IO generated USD1.5 billion.
Stimulation of High-Temperature Sandstone Formations From West Africa With Chelating Agent-Based Fluids
Authors: Ali S. , Ermel E. , Clarke J. , Fuller M. J. , Xiao Z. , Malone B. 
Published: February 2008

Summary
Fluids based on chelating agents have been developed for matrix stimulation of high-temperature sandstone formations. These fluids dissolve sizeable amounts of calcite and clays and maintain high levels of dissolved metal in solution over time with minimal precipitation. A series of field samples from high-temperature (149°C) sandstone reservoirs in a West African formation bear carbonate concentrations ranging from 2% to 37% (w/w). The effects of matrix treatment using a chelating agent-based system on these field samples were studied using coreflood and slurry reactor experiments.
Linear coreflood test data show dramatic increases in the formation permeability after treatment with the chelating agent-based fluid. The improvement in permeability is ascribed to the removal of carbonate minerals and soluble clays, without secondary metal precipitation. Slurry reactor tests elucidated the kinetics of mineral dissolution in mechanically ground field samples. Treatment with acidic chelant fluids generated high levels of dissolved calcium, silicon, and aluminum that remained in solution over time. For comparison, conventional mineral-acid treatment of the field samples generated high levels of metals in solution that declined over the same period of time, which is indicative of secondary precipitation. The effectiveness of the chelant fluid for stimulation of this high-temperature formation was confirmed through increased formation permeability and high levels of dissolved minerals.
Simultaneous Chemical and Sensory Characterization of Volatile Organic Compounds and Semi‐Volatile Organic Compounds Emitted from Swine Manure using Solid Phase Microextraction and Multidimensional Gas Chromatography–Mass Spectrometry–Olfactometry
Authors: Lo Yin‐Cheung M. , Koziel Jacek A. , Cai Lingshuang , Hoff Steven J. , Jenks William S. , Xin Hongwei 
Published: February 2008

AbstractSwine manure is associated with emissions of odor, volatile organic compounds (VOCs) and other gases that can affect air quality on local and regional scales. In this research, a solid phase microextraction (SPME) and novel multidimensional gas chromatography–mass spectrometry–olfactometry (MDGC‐MS‐O) system were used to simultaneously identify VOCs and related odors emitted from swine manure. Gas samples were extracted from manure headspace using Carboxen/polydimethylsiloxane (PDMS) 85‐μm SPME fibers. The MDGC‐MS‐O system was equipped with two columns in series with a system of valves allowing transfer of samples between columns (heartcutting). The heartcuts were used to maximize the isolation, separation, and identification of compounds. The odor impact of separated compounds was evaluated by a trained panelist for character and intensity. A total of 295 compounds with molecular weights ranging from 34 to 260 were identified. Seventy one compounds had a distinct odor. Nearly 68% of the compounds for which reaction rates with OH·radicals are known had an estimated atmospheric lifetime <24 h.
Methane Emissions from Free‐Ranging Cattle: Comparison of Tracer and Integrated Horizontal Flux Techniques
Authors: Griffith David W. T. , Bryant Glenn R. , Hsu David , Reisinger Andy R. 
Published: February 2008

AbstractAccurate measurements of methane (CH4) emission rates from livestock in their undisturbed natural environments are required to assess their impacts on radiative forcing (i.e., enhanced greenhouse effect) and the environment. Here we compare results from two nonintrusive techniques for the measurement of CH4 emissions from cattle. The cows were kept in an outdoor feeding strip that allowed them to follow natural behavioral patterns but contained them within a well defined space. In the first technique, nitrous oxide (N2O) was released as a tracer at the upwind edge of the feeding strip, and the downwind concentrations of N2O and CH4 were measured simultaneously using Fourier transform infrared (FTIR) spectroscopy. Average CH4 emission per cow was calculated each half‐hour on three separate days from the correlation between the two gases. The second technique was the integrated horizontal flux (IHF) or 1‐D mass‐balance method, in which we used the measured vertical profiles of CH4 concentration and windspeed downwind of the cows to determine the total CH4 emission. Comparing the IHF results to the known release rate of N2O allowed us to test the IHF technique independently. We found agreement within 10% for all comparisons on all days. The daily CH4 emission rate averaged over all tracer and IHF measurements was 342 g CH4 head−1 d−1 This is within the range of previous measurements for mature lactating dairy cattle (200–430 g CH4 head−1 d−1) but higher than expected for yearling cattle. The high CH4 emissions are accompanied by high CO2 emissions determined from the FTIR measurements. The bias is most likely due to the measurements being made during and after supplementary feeding of the cattle.
Sorption of the Antibiotic Tetracycline to Humic‐Mineral Complexes
Authors: Gu Cheng , Karthikeyan K. G. 
Published: February 2008

AbstractHumic substances, by altering the surface properties and/or competing for available reaction sites, can either suppress or promote sorption of organic compounds to mineral surfaces. Limited literature evidence points to the reduction in sorption of the antibiotic tetracycline to clay minerals in the presence of humic substances. We investigated the surface interaction of Elliott soil humic acid (ESHA) with hydrous Al oxide (HAO) and the effect of this association on tetracycline sorption. Strong interaction between ESHA and HAO led to ESHA‐promoted dissolution of HAO and surface charge reversal. The ESHA‐HAO sorption–desorption isotherms were successfully described using a modified Langmuir model that accounted for the heterogeneity of HAO surface and ESHA. Ligand exchange was proposed as the major interaction mechanism, and the edge Al atoms on HAO surface were considered as the sorption sites for ESHA macromolecules. ESHA was coated onto HAO to achieve two different organic content (foc) levels of 0.81 and 1.52%. Sorption results were compared for the binary ESHA‐tetracycline and HAO‐tetracycline systems, and the ternary ESHA‐HAO‐tetracycline system. The coating of ESHA on HAO significantly suppressed tetracycline sorption levels, attributable to altered HAO surface charge characteristics and/or direct competition between ESHA and tetracycline for potential sorption sites. Higher foc level, besides increasing the extent of sorption suppression, also resulted in greater ionic strength dependence and increased nonlinearity of sorption behavior. It, therefore, appears that the presence of humic substances, in both dissolved and mineral‐bound forms, is likely to increase the environmental mobility of tetracycline compounds.
Persistent Elevated Nitrate in a Riparian Zone Aquifer
Authors: Robertson William D. , Schiff Sherry L. 
Published: February 2008

AbstractStreamside vegetated buffer strips (riparian zones) are often assumed to be zones of ground water nitrate (NO3−) attenuation. At a site in southwestern Ontario (Zorra site), detailed monitoring revealed that elevated NO3−–N (4–93 mg L−1) persisted throughout a 100‐m‐wide riparian floodplain. Typical of riparian zones, the site has a soil zone of recent river alluvium that is organic carbon (OC) rich (36 ± 16 g kg−1). This material is underlain by an older glacial outwash aquifer with a much lower OC content (2.3 ± 2.5 g kg−1). Examination of NO3−, Cl−, SO42−, and dissolved organic carbon (DOC) concentrations; N/Cl ratios; and NO3− isotopic composition (δ15N and δ18O) provides evidence of four distinct NO3− source zones within the riparian environment. Denitrification occurs but is incomplete and is restricted to a narrow interval located within ∼0.5 m of the alluvium–aquifer contact and to one zone (poultry manure compost zone) where elevated DOC persists from the source. In older ground water close to the river discharge point, denitrification remains insufficient to substantially deplete NO3− Overall, denitrification related specifically to the riparian environment is limited at this site. The persistence of NO3− in the aquifer at this site is a consequence of its Pleistocene age and resulting low OC content, in contrast to recent fluvial sediments in modern agricultural terrain, which, even if permeable, usually have zones enriched in labile OC. Thus, sediment age and origin are additional factors that should be considered when assessing the potential for riparian zone denitrification.
Storage and Dynamics of Carbon and Nitrogen in Soil after Grazing Exclusion in Leymus chinensis Grasslands of Northern China
Authors: Wu L. , He N. , Wang Y. , Han X. 
Published: February 2008

AbstractLand‐use change can lead to changes in soil carbon (C) and nitrogen (N) storage. This study aimed to determine the impact of long‐term grazing exclusion (GE) on soil organic C and total N (TN) storage in the Leymus chinensis grasslands of northern China and to estimate the dynamics of recovery after GE. We investigated the aboveground biomass and soil organic C and TN storage in six contiguous plots along a GE chronosequence comprising free grazing, 3‐yr GE, 8‐yr GE, 20‐yr GE, 24‐yr GE, and 28‐yr GE. Grazing exclusion for two decades increased the soil C and N storage by 35.7 and 14.6%, respectively, in the 0‐ to 40‐cm soil layer. The aboveground net primary productivity and soil C and N storage were the highest with 24‐yr GE and the lowest with free grazing. The storage increased logarithmically with the duration of GE; after an initial rapid increase after the introduction of GE, the storage attained equilibrium after 20 yr. A logarithmic regression analysis revealed 86.8 and 87.1% variation in the soil C storage and 74.2 and 80.7% variation in the soil N storage in the 0‐ to 10‐cm and 0‐ to 40‐cm soil layers, respectively. Based on these results, we suggest that two decades of GE would restore the L. chinensis grasslands from being lightly degraded to a stable productive condition with good soil C and N storage capacity. Our results demonstrated that by implementing GE, the temperate grasslands of northern China could facilitate significant C and N storage on decade scales in the context of mitigating global climate change.
Use of a Low‐Cost Biosorbent to Remove Pesticides from Wastewater
Authors: Boudesocque Stéphanie , Guillon Emmanuel , Aplincourt Michel , Martel Frédéric , Noël Sandrine 
Published: February 2008

AbstractA lignocellulosic substrate (LS) obtained from our local agroindustry was used as a low‐cost and effective adsorbent for the removal of pesticides from wastewaters. The studied pesticides were terbumeton (N‐(1,1‐dimethyl)‐Nethyl‐6‐methoxy‐1,3,5‐triazine‐2,4‐diamine), desethyl terbumeton (N‐(1,1‐dimethylethyl)‐6‐methoxy‐1,3,5‐triazine‐2,4‐diamine), dimetomorph (4‐[3‐(4‐chlorophenyl)‐3‐(3,4‐dimethoxyphenyl)acryloyl]morpholine), and isoproturon (3‐(4‐isopropylphenyl)‐1,1‐dimethylurea). Batch and column experiments were conducted as a function of pH and pesticide concentration under laboratory and industrial conditions. The concentration range studied for the pesticides varied from 2 × 10−7 to 3 × 10−4 mol L−1 The influence of organic and inorganic pollutants was assessed by studying the retention of pesticide in the presence of copper(II) and a surfactant. These experiments indicated that LS is an efficient adsorbent toward the investigated pesticides and has little influence of the other pollutants. The kinetic adsorptions are fast, and the amounts of adsorbed pesticide varied from 1 to 8 g kg−1 of LS. These retention capacities show that LS can provide a simple, effective, and cheap method for removing pesticides from contaminated waters. Thus, this biomaterial may be useful for cleaning up polluted waters.
Microbial Populations and Enzyme Activities in Soil In Situ under Transgenic Corn Expressing Cry Proteins fromBacillus thuringiensis
Authors: Icoz I. , Saxena D. , Andow D. A. , Zwahlen C. , Stotzky G. 
Published: February 2008

AbstractTransgenicBtcrops produce insecticidal Cry proteins that are released to soil in plant residues, root exudates, and pollen and that may affect soil microorganisms. As a continuation of studies in the laboratory and a plant‐growth room, a field study was conducted at the Rosemount Experiment Station of the University of Minnesota. ThreeBtcorn varieties that express the Cry1Ab protein, which is toxic to the European corn borer (Ostrinia nubilalisHübner), and oneBtcorn variety that expresses the Cry3Bb1 protein, which is toxic to the corn rootworm complex (Diabroticaspp.), and their near‐isogenic non‐Btvarieties were evaluated for their effects on microbial diversity by classical dilution plating and molecular (polymerase chain reaction‐denaturing gradient gel electrophoresis) techniques and for the activities of some enzymes (arylsulfatases, acid and alkaline phosphatases, dehydrogenases, and proteases) involved in the degradation of plant biomass. After 4 consecutive years of corn cultivation (2003–2006), there were, in general, no consistent statistically significant differences in the numbers of different groups of microorganisms, the activities of the enzymes, and the pH between soils planted withBtand non‐Btcorn. Numbers and types of microorganisms and enzyme activities differed with season and with the varieties of corn, but these differences were not related to the presence of the Cry proteins in soil. The Cry1Ab protein ofBtcorn (events Bt11 and MON810) was detected in most soils during the 4 yr, whereas the Cry3Bb1 protein was not detected in soils ofBtcorn (event MON863) expressing thecry3Bb1gene.