bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physics-Driven Interface Modeling for Drainage and Imbibition in Fractures
Authors: Prodanovic Maša , Bryant Steven L. 
Published: November 2009

Summary
The geometric distribution of immiscible fluid phases in fractures is not readily accessible experimentally, so aperture-scale simulations of drainage and imbibition in realistic fractures can provide valuable insight. We implement a level set method for computing the location within a fracture of the interface between two fluids controlled by capillary forces. The movement of the interface in response to changes in capillary pressure is approximated as quasistatic displacement. Fluid interfaces are thus constant mean curvature surfaces, satisfying the Young-Laplace equation. We apply a progressive quasistatic (PQS) algorithm to determine when spontaneous pore-level events occur during fluid displacement. The algorithm captures reversible and irreversible behavior. We illustrate the approach in two types of rough-walled fractures. One type is a 3D crack between irregular, impermeable surfaces; the other type is a gap between irregular 2D and 3D grain packs. We focus on the disconnected (defending) fluid volumes and (advancing) fluid main pathway as the geometric properties of the fracture are varied, notably aperture and the number of contact points between the upper and lower fracture surfaces. The curvature of the fluid/fluid interface in the plane of the fracture is often ignored by invasion percolation simulation techniques, yet it is known to influence strongly the fluid cluster properties. Our simulations establish the exact position and shape of the interface in realistic fracture geometries, from which fluid volumes, contact areas, and interface curvatures can be obtained. This establishes a new, mechanistic basis for predicting relative permeabilities in fractures and for evaluating transfer functions in dual-porosity flow models.
Well-Integrity Issues Offshore Norway
Authors: Vignes Birgit , Aadnøy Bernt S. 
Published: November 2009

Summary
A number of serious well failures in recent years led to investigations of well-integrity issues. The Petroleum Safety Authority Norway (PSA) performed a pilot well-integrity survey based on supervisory audits and requested input from seven operating companies, 12 preselected offshore facilities, and 406 wells. The wells were a representative selection of production and injection wells with variation in both age and development categories.
The pilot project indicates that 18% of the wells in the survey have integrity failure, issues, or uncertainties, and 7% of these are shut in because of well-integrity issues. The selection of wells and the companies indicate that the statistics are representative.
The well incidents in the past and the results of the pilot well-integrity survey revealed that the industry needs to increase focus on barrier philosophy. Control of barrier status is an important health, safety, and environment (HSE) factor to avoid major incidents caused by unintentional leaks and well-control situations. Knowledge of well-integrity status at all times enables the companies to take the right actions in a proactive manner to prevent incidents.
The paper presents the results and the conclusions from the pilot survey. In addition, a number of technical well failures will be presented, identifying critical elements such as corrosion, leaks, and operational factors. In particular, the understanding of barrier regulations, standards, and implementation was found to be inadequate.
Particulate-Based Loss-Prevention Material—The Secrets of Fracture Sealing Revealed!
Authors: Kaageson-Loe N. , Sanders M. W. , Growcock F. , Taugbøl K. , Horsrud P. , Singelstad A. V. , Omland T. H. 
Published: November 2009

Summary
Owing to the narrow drilling margin that exists between the pore-pressure and the fracture-pressure gradient, drilling in depleted-reservoir, high-pressure/high-temperature, and deepwater environments is universally recognized as being technically challenging.
A number of field techniques are available for mitigating many of the drilling problems encountered. Included among these are specialized fluid engineering that involves the use of chemical- and particulate-based treatments for minimizing or preventing losses. In many instances, these techniques can be used to strengthen or stabilize the wellbore when drilling at or near the fracture gradient, thereby potentially eliminating the need for intermediate casing strings.
This paper discusses particulate-based-treatments design for sealing fractures. Substantial experience gained from innovative laboratory testing has highlighted the mechanisms and many factors that determine the effectiveness of the fracture seal. The particle-size distribution (PSD) relative to the fracture aperture, particle morphology, volumetric concentration, rheological properties of the fluid, and fluid-loss control influence whether the seal is established within the fracture or at the fracture mouth. Understanding this distinction is important with respect to selecting the optimum treatment and its application for given field conditions. Parameters critical for optimizing the treatment have been identified and are discussed in the context of laboratory and field experience.
Automatic Measurement of Drilling Fluid and Drill-Cuttings Properties
Authors: Saasen A. , Omland T. H. , Ekrene S. , Brévière J. , Villard E. , Kaageson-Loe N. , Tehrani A. , Cameron J. , Freeman M. , Growcock F. , Patrick A. , Stock T. , Jørgensen T. , Reinholt F. , Amundsen H. E. F. , Steele A. , Meeten G. 
Published: November 2009

Summary
To remotely control the drilling process, it is necessary to measure several drilling-fluid parameters automatically. This will increase objectivity of the measurements and make it possible to react to changes in real time. The current paper describes in detail the design for an integrated tool combination and the results of a full-size yard test of such a combined set of tools for measuring drilling-fluid parameters and formation properties automatically. Some of the automated tools have been tested on rigsite operations. Results from these individual tests are also presented.
The automatic drilling-fluid analysis includes viscosity, fluid loss, electrical-stability (ES) measurements, and chemical properties such as pH. Full viscosity curves for the drilling fluid are measured using configurations and shear rates similar to those suggested by American Petroleum Institute (API) procedures. Because gel-formation curves and fluid-loss properties require some sort of controlled static periods, these measurements are made semicontinuously. However, they are automatic and can be measured as frequently as desired.
An automatic system is included to measure the particle-size distribution (PSD), concentration, and morphology. Knowledge of these parameters is necessary, especially when drilling in depleted reservoirs where particles are added for increasing the wellbore strength.
The produced-cuttings volume is measured. An automatic system is adapted that determines, with accuracy comparable to that of visual analysis, whether the particles separated at the shaker screens are drill cuttings or cavings produced by an unstable formation. The mineralogy of the cuttings is analyzed automatically using Raman spectroscopy, making it possible to evaluate continuously the different formations being drilled.
Dual Role of Catalytic Agents on In-Situ Combustion Performance
Authors: Akkutlu I.Y.. Y. , Yortsos Y.C.. C. , Adagülü-Demirdal G.D.. D. 
Published: November 2009

Summary
Unlike other thermal recovery methods, air injection and in-situ combustion generates significant amounts of heat in the reservoir. However, the process is subject to acute heat loss rates from the reaction zones because of high temperature gradients; consequently, the reaction temperatures may be reduced considerably, leading to a deteriorated combustion performance and debilitated field operations. The goal of this paper is to determine under which reservoir conditions the combustion temperatures could be maintained at sufficient levels. Previous investigators have partially addressed this issue using kinetic and combustion tube experiments. In the absence of heat losses, it has been repeatedly shown that catalytic agents (naturally occurring clays, metal oxides, and some water-soluble metallic additives) improve the self-sustainability limit of combustion front in crude oil and sand mixtures. In general, this has been attributed to the dual role of these agents on the combustion performance, namely the catalytic and fuel deposition effects. It is currently a common belief that appropriate introduction of such materials in a reservoir environment could enhance the performance of combustion process and, hence, improve the recoveries. An investigation of their dual role on combustion requires that the mechanisms of combustion are well understood in their presence. Complex physical and chemical nature of the problem at the pore-scale has prevented detailed investigations using physical and numerical models, however. Here, we approach the problem analytically using a sequential-reaction [high-temperature oxidation/low-temperature oxidation (HTO/LTO)] combustion front propagation model, based on large activation energy asymptotics, and introducing the reaction kinetics and fuel deposition effects to the model systematically by varying the related variables and parameters. Coherent propagation of the reaction regions are then investigated using reaction region temperatures, propagation velocity, and the oxygen consumption efficiency. General characteristics of an ideal catalytic agent are discussed in terms of its potential to improve in-situ combustion. It is found that the front propagation can be improved under the reservoir conditions only if both the catalytic and fuel deposition effects of the agents are present. The work is important for our understanding of in-situ combustion processes and can be used for development of screening criteria to identify high-performance catalytic agents in the laboratory using conventional apparatus.
Corporate Venture Capital as a Conduit for Early Adoption of Emerging Technology: A Decade of Experience
Authors: Unneland Trond , Hanten John 
Published: November 2009

Summary
A continuous challenge in the petroleum industry is to identify and rapidly implement new technologies into field operations to increase production, improve employee productivity, and lower costs. Utilizing new world-class technology is critical as the industry moves towards more complex environments. To support this trend, a Chevron corporate strategy is to leverage technology to deliver superior performance and growth. A range of suitable tools are available, such as internal R&D, joint ventures, and collaboration with academia and service companies. A less traditional method in the petroleum industry is to use corporate venture capital (VC) as a tool to gain access to world-class technology. This paper covers a decade of Chevron VC experience, including justification for corporate VC investments, how success is measured, financial and strategic yield, investment criteria, governance, partnerships, track record, and portfolio highlights. In this paper, several technology transfer success stories are given including the financial and operational value they created for the Chevron business units. The investments cover such diverse technology areas as artificial lift, seismic monitoring, deepwater technology, wind power, and high-end computing for reservoir simulation.
On-Site Bioremediation Systems Reduce Crude Oil Contamination
Authors: Hildebrandt W.W. , Wilson S.B. 
Published: November 2009

Summary
Oilfield properties frequently have areas where soils contain concentrationsof crude oil. These soils can be either"hazardous wastes" or"designated wastes" under regulatory guidelines. As a result, propertyowners and financial institutions face potential liabilities when oilfieldproperties are transferred to new operators, abandoned, or converted to otheruses.
Modern, well-designed soil bioremediation systems are cost-effective ways totreat soils that contain concentrations of crude oil, and these systems caneliminate an owner's subsequent liabilities. A modern on- sitebioremediation system requires significantly less surface area, results inlower operating costs, and provides more effective, expeditious results thantraditional land-farming practices. It also eliminates potential long-termliabilities and is typically more cost-effective than excavation and off-sitedisposal of oilfield soils. Case studies indicate that on-site bioremediationsystems have reduced crude oil contamination in soil to levels acceptable toregulatory agencies in less than 20 weeks (in some cases, less than 10 weeks). Total costs for on-site bioremediation range from $35 to $120/yd3oftreated soil, including excavation, depending on specific siterequirements.

Introduction
During normal operation of oilfield properties, crude oil or other materialsfrequently leak or spill onto land surfaces. These degraded soils are commonlyassociated with oil wells, sumps and pits, tank batteries, gathering lines, andpump stations. Crude oil and drilling muds may also be found in these areasand, like the contaminated soil, they may be considered either hazardous wastesor designated wastes under current regulatory guidelines. The regulationspertaining to crude oil vary across the U.S. In California, for example, crudeoil is considered a designated waste and its off-site disposal is subject toregulations. If certain constituents (e.g., benzene) are present insufficiently high concentrations, the soil degraded by crude oil may beconsidered a hazardous wasteand subject to additional regulations. Crude oilsludge in an old sump typically contains oilfield treatment chemicals;therefore, the sludge is considered a hazardous waste.
Initiation and Persistence to Statin Treatment in Patients with Diabetes Receiving Glucose-Lowering Medications 1997- 2006
Authors: Dominguez H. , Schramm T. K. , Norgaard M. L. , Abildstrøm S.Z. , Kober L. , Jørgensen C. , Guterbaum T.J. , Poulsen H.E. , Torp-Pedersen C. , Gislason G. H. 
Published: November 2009

Aims:Since 2001 guidelines recommend statin treatment in most patients with diabetes. We investigated secular changes in initiation and persistence to statin treatment during a 10-year period in a nationwide cohort of patients initiating glucose-lowering medication (GLM).Methods:All Danish citizens 30 years and older who claimed prescriptions of GLM between 1997 and 2006 were identified from nationwide registers of drug dispensing from pharmacies and hospitalizations, and followed until 2006. Statin treatment was registered if a prescription was claimed during the period. By logistic regression we analyzed factors related to initiation and persistence to statin treatment.Results:In total 128,106 patients were included. In 1997 only 7% of the patients receiving GLM claimed statins within the first year after GLM initiation. Despite increasing statin prescriptions the following years, only 62% were using statins at the end of follow up. The chance of ever receiving statins was lowest if not initiated within 180-days following the first purchase of GLM (OR 0.75, 95% CI 0.74-0.76). A previous myocardial infarction was associated with increased statin treatment (OR 4.51; 95% CI 4.31 - 4.71), while low income was associated with lower use of statins (OR 0.68; 95%CI 0.66-0.72). Between 75-85 % of the patients who initiated statins treatment were persistent to treatment by 2007.Conclusions:In spite of increasing use of statins in diabetes patients over time, many patients remain untreated. Early initiation of statin treatment in diabetic patients and focus on patients with low socioeconomic status is needed to give long-term benefits.
Outbreak of trichinellosis in eastern Slovakia
Authors: Paraličová Z. , Kinčeková J. , Schréter I. , Jarčuška P. , Dubinský P. , Porubčin Š. , Pavlinová J. , Kristian P. 
Published: November 2009

Abstract
Trichinellosis is a zoonosis caused by ingestion of undercooked raw meat from animals that harbour infectious larvae. In most of the Slovak regions there is ongoing life cycle of circulating trichinellosis in wild carnivores and wild boar population. The outbreak of trichinellosis occured in Rožňava district east Slovakia during spring in 2008. Ten members of farmer’s family and their relatives got ill while processing meat from home-made pig-slaughter for meals and meat products intended for wedding dinner. During the meat processing all of them tasted raw meat. Moreover, another 45 persons were exposed to this infection by eating heat-treated meat products. The most common predominant clinical signs were: myalgias, fever, fatigue, exanthema and periorbital oedema. On the 40th day after infection there were intermediate to high titres of trichinella IgG antibodies detected (10 patients), high levels of eosinophilia (10 patients) with maximum of 6.76 × 109/l (55 %) and profound changes in selected laboratory parameters: decreased levels of total proteins, increased levels of alpha 1-globulin and C reactive protein. Presence of IgG antibodies as well as aforementioned laboratory parameters was important markers of trichinellosis in our study, whereas other laboratory changes (leukocytosis, high levels of activity lactate dehydrogenase and creatine kinase) were detected only in few hospitalized patients.
Ecological aspects of metazoan endoparasites of Metynnis lippincottianus (Cope, 1870) (Characidae) from Upper Paraná River floodplain, Brazil
Authors: Moreira L. , Takemoto R. , Yamada F. , Ceschini T. , Pavanelli G. 
Published: November 2009

Abstract
We examined 44 specimens of Metynnis lippincottianus (Cope, 1870) (Characidae), collected in the Upper Paraná River floodplain, Brazil, from March 2006 to December 2007. Of the total number of fishes, 32 (72.7 %) were infected by at least one species of helminth (endoparasites). One digenean, Dadayus pacupeva, and four nematode species, Spinoxyuris oxydoras, Contracaecum sp. (larval stage), Procamallanus (Spirocamallanus) inopinatus and Raphidascaris (Sprentascaris) mahnerti were identified. D. pacupeva and S. oxydoras showed the highest values of prevalence, mean intensity and abundance. The typical pattern of overdispersion or aggregation was observed for all endoparasites. Dominance by D. pacupeva and S. oxydoras was observed in the parasite community. Positive association between D. pacupeva and two nematode species (S. oxydoras and P.(S.) inopinatus) was observed, including positive and significant covariation between their abundances. These results suggest that species are coexisting without competition. There was no correlation between parasitism and sex for M. lippincottianus.
Echinoparyphium limosorum n. sp. (Trematoda: Echinostomatidae) from Black-tailed Godwit, Limosa limosa (Aves, Charadriiformes) in Slovakia
Authors: Macko J. , Špakulová M. , Macková A. 
Published: November 2009

Abstract
Echinostomatid trematode Echinoparyphium limosorum n. sp. from the charadriiform bird Limosa limosa is described on basis of morphometrical study of museum material. The new species is characterized by medium-sized body up to 4.9 mm long, reniform head collar up to 511 wide, armed with 48–51 collar spines up to 91 µm, arranged in double row. The new species is largely similar to Echinoparyphium recurvatum, however, the most remarkable difference lays in the higher number of collar spines which are 48–51 in E. limosorum n. sp. but 45 in E. recurvatum. The authors discuss relative impact of numerical generic characters and propose an amending of the diagnosis of The genus Echinoparyphium given by Kostadinova (2005) as follows: Collar spines up to 51, sharply pointed, all in double row.
Influence of arbuscular mycorrhizal fungi on the nematicidal properties of leaf extracts of Thymus vulgaris L.
Authors: Sasanelli N. , Anton A. , Takács T. , D’Addabbo T. , Birò I. , Malov X. 
Published: November 2009

Abstract
The effect of arbuscolar mycorrhizal fungi (AMF) on the nematicidal activity of Thymus vulgaris against the rootknot nematodes Meloidogyne incognita and M. javanica was investigated in two in vitro experiments. In the first experiment egg masses of M. incognita and M. javanica were immersed for 3 weeks in aqueous leaf extracts of thyme plants non-inoculated or previously inoculated with Glomus mosseae or mixed AMF strains (Sclerocystis sinuosa, Glomus claroideum-1, G. claroideum-2 and G. claroideum-3). Thereafter the hatching test continued in distilled water for five more weeks. In the second experiment egg masses of both Meloidogyne species were exposed to the different thyme extracts for 4, 8 and 16 hours and then incubated in distilled water for 8 weeks. Distilled water and 5 mg/ml aqueous solution of fenamiphos nematicide were used as controls. Numbers of second stage juveniles emerging weekly were expressed as cumulative percentages of the total egg content of the egg masses. In the first experiment juvenile emergence from eggs of both Meloidogyne species immersed in thyme extracts for three weeks was completely suppressed since the first week. Hatching of eggs of M. incognita in all the extracts was significantly lower than that in water control, although emergence in the extract from uninoculated thyme plants was significantly higher than the others and no statistical different from that of aqueous fenamiphos solution. Emergence of M. javanica juveniles was significantly lower after immersion in all the extracts than in distilled water control and aqueous fenamiphos solution. In the second experiment a 4-hour exposure to the extract from thyme inoculated with G. mosseae and mixed AMF population significantly reduced the final hatch of M. incognita in comparison to distilled water. A 16-hour exposure to the extract from mixed AMF inoculated plants resulted in a significantly lower egg hatch than the shorter exposure times, whereas no statistical difference was found between 4 and 8 hour exposure to both extracts. Emergence of M. javanica juveniles was statistically lower than in water only after 16 hours exposure to the extracts from mixed AMF strains inoculated plants, but no difference was found among the different exposure times. Growth of T. vulgaris was significantly increased only by the infections of mixed AMF strains.
A New Species of the Genus <i>Phanerotoma</i> Wesmael (Braconidae: Cheloninae) with a key to Indian Species
Authors: Sheeba M , Narendran TC 
Published: November 2009

A new species of Phanerotoma viz., P. malabarica Sheeba & Narendran sp. nov. from India is described and compared with its closest relative. A key to Indian species of Phanerotoma is also provided. Key words: Phanerotoma, Braconidae, Cheloninae, New species, P. malabarica DOI:10.3329/jbs.v16i0.3734 J. bio-sci. 16: 11-14, 2008
Karyotype Analysis of Seven Varieties of Taro <i>Colocasia esculenta</i> (L.) Schott. from Bangladesh
Authors: Parvin S , Kabir G , Ud-Deen MM , Sarker JK 
Published: November 2009

Nuclear and chromosome characteristics of seven varieties of Colocasia esculenta were studied. Interphase chromosome value was found to range from 2119.85 (cytotype-3) to 5346.12 (cytotype-7). Heterochromatin values varied from 23.17 (cytotype-2) to 44.52% (cytotypt-6) in meristematic cells. Karyotype studies revealed that somatic chromosome number was 28 in cytotype-1, 2, 5, 6 and 7; 42 in cytotype-3 and 21 in cytotype-4. The longest chromosome (5.54 μm) was observed in cytotyopt-2 and shortest (1.3 μm) in cytotype-3 and 6. Key words: Karyotype, Nuclear phenotype, Colocasia esculenta. DOI:10.3329/jbs.v16i0.3735 J. bio-sci. 16: 15-18, 2008